JP4896183B2 - Document illumination device and image reading device - Google Patents

Description

The present invention relates to a document illumination device and an image reading device.

  Conventionally, various techniques related to an image reading apparatus have been proposed.

  For example, Patent Document 1 discloses an image reading apparatus that reads reflected image from a document illuminated by a light source onto an image sensor with an imaging lens and reads an image of the document. An image reading apparatus is disclosed in which the light source is provided at a position overlapping with a part of the effective pupil of the imaging lens when viewing the image.

  Patent Document 2 discloses an image reading apparatus that reads a document image line-sequentially with a one-dimensional imaging element and an imaging lens by illuminating a document surface with a one-dimensional light source and scanning the document. A half mirror that guides light from the one-dimensional light source to the imaging lens is installed between the imaging lenses, and an optical system is configured so that the perpendicular to the document surface does not coincide with the reading optical axis of the imaging lens An image reading apparatus is disclosed that is characterized by:

  Here, an example of a general image reading apparatus having a reduction optical system as disclosed in Patent Documents 1 and 2 will be described with reference to FIG.

  1A and 1B are a schematic view of a general image reading apparatus and a cross-sectional view of the image reading apparatus in the sub-scanning direction, respectively.

  In the image reading apparatus (100), an original (107) such as a sheet and a book is placed on a transparent glass contact glass (original table) (108), and the light from the illumination lamp (109) and the illumination lamp ( 109) The reflected light from the reflector (110) that has received the light leaking from 109) is irradiated to the imaging area (Ai) of the document (107). The illumination lamp (109) is, for example, a cold cathode tube, and a part of the tube wall is a window. The light from the illumination lamp (109) is applied to the imaging area (Ai) of the document (107) through the window. The first traveling body (103) integrally includes an illumination lamp (109), a reflector (110), and a turning mirror (112), and the second traveling body (104) includes a folding mirror A (111a) and a folding mirror. It has a mirror B (111b). Then, the reflected light from the imaging region (Ai) is reflected by the turning mirror (112) in the first traveling body (103), the folding mirror A (111a) and the folding mirror B (111b) in the second traveling body (104). ) And imaged on the one-dimensional image sensor (101) by the imaging lens (102). The folding mirror A (111a) and the folding mirror B (111b) maintain the orientation of the image of the reflected light from the turning mirror (112). The imaging lens (102) is generally an optical system including a plurality of lenses integrated by a lens barrel. In this way, the one-dimensional imaging element (101) acquires a one-dimensional image of the line-shaped imaging region (Ai) and converts it into an electrical signal. The direction in which the one-dimensional image sensor (101) acquires the one-dimensional image is referred to as a main scanning direction (Sx). A system including the imaging lens (102) and the one-dimensional image sensor may be referred to as a reading unit.

  In the image reading apparatus (100), the first traveling body (103) and the second traveling body (104) receive the driving force of the motor (105) through the drive transmission means (106), and the first traveling body (103) The traveling body (103) travels at a speed that is twice the speed of the second traveling body (104). As a result, the imaging position of the imaging lens (102) with respect to the surface of the contact glass (108) is maintained on the surface of the one-dimensional imaging device (101), and light is captured in a line shape on the surface of the contact glass (108). It runs in a direction perpendicular to the area (Ai) and parallel to the contact glass (108). In this manner, the image of the document (107) placed on the contact glass (108) is sequentially read out by the one-dimensional image sensor (101) and acquired two-dimensionally. Here, the reading area of the document (107) is the product of the range read by the one-dimensional imaging device (101) and the traveling distance of the second traveling body (104). A direction in which the first traveling body (103) and the second traveling body (104) travel in parallel with the contact glass (108) is referred to as a sub-scanning direction (Sy). The sub-scanning direction (Sy) is orthogonal to the main scanning direction (Sx).

  Usually, a one-dimensional CCD (sometimes simply referred to as a CCD) is used as a one-dimensional imaging device, and the imaging lens (102) reduces the image on the surface of the contact glass (108) by reducing it. An image is formed on the one-dimensional image sensor (101).

  Further, since the ratio of the traveling speeds of the first traveling body (103) and the second traveling body (104) is set to 2: 1, the moving distance of the second traveling body (104) is the first traveling body. The distance from the imaging region (Ai) to the imaging lens (102) or the one-dimensional imaging device (101) is half of the moving distance of the body (103), and the first traveling body (103) and the second traveling body ( 104) is constant regardless of the position.

  Usually, a monochrome scanner uses one one-dimensional CCD, and the image resolution of the scanner is expressed in DPI (dot / inch). The image resolution of a scanner mounted on a digital PPC is often 400 to 600 DPI. It is. On the other hand, color scanners use three one-dimensional CCDs that are sensitive to the spectrum of R (red), G (green), or B (blue) light, and share the optical path length from the CCD to the document. I have to. However, a 3-line CCD in which 3-line CCDs having color filters for (red), G (green), or B (blue) are arranged in the sub-scanning direction (Sy) may be used as an image sensor. In this case, the distance between the pixel columns is about 4 to 8 dots in the main scanning reading area of the CCD pixel, and the pixel columns are not necessarily integrated. Therefore, when a three-line CCD is used as the image sensor of the image reading apparatus, the reading position of the document corresponding to each of the RGB CCD pixels differs in the sub-scanning direction (Sy). It is necessary to irradiate the reading position corresponding to each color.

  However, the image reading apparatus as described above has several problems.

  FIG. 2 is a diagram for explaining one of the problems related to illumination of a document in the image reading apparatus.

  The light generated in the cold-cathode tube illumination lamp (201) mounted on the first traveling body of the image reading apparatus is reflected by the fluorescent screen (202) and passes through the opening (203) of the cold-cathode tube. Released as (204). The illumination light (204) emitted from the illumination lamp (201) directly illuminates the imaging area (Ai) of the document placed on the contact glass (205), or the reflector (206) mounted on the first traveling body. To illuminate the imaging area (Ai) of the document. FIG. 2 shows the illuminance distribution (Di) of the illumination light (204) in the vicinity of the imaging region (Ai).

  However, the illumination light for illuminating the imaging region (Ai) by the cold cathode tube illumination lamp (201) and the reflector (206) mounted on the first traveling body is light generated in the cold cathode tube illumination lamp (201). The efficiency of illuminating the imaging region (Ai) with the illumination lamp (201) and the reflector (207) is very low. The length of the imaging region (Ai) in the sub-scanning direction (Sy) is about 0.1 mm when using a one-line CCD, and when using a three-line CCD for reading a color document, It is about 1 mm. Nevertheless, the illuminance distribution (Di) of the illumination light (204) in the sub-scanning direction (Sy) spreads over a wide range of several tens of mm centering on the imaging region (Ai).

  Moreover, the structure of the cold-cathode tube itself of the illumination lamp (201) and the lighting device (generating a high voltage) are complicated.

  FIG. 3 is a diagram for explaining another problem related to illumination of a document in the image reading apparatus. As shown in FIG. 3, when reading a book document (302) placed on the contact glass (301), the illuminance by the illumination light (303) directly illuminated from the illumination lamp is higher than the illuminance by the reflected light from the reflector. Since it is several times higher, the illuminance is insufficient at the reading position of the central portion (304) of the book original (302), and the central portion (304) of the book original (302) is read as a black image (Ad). May occur.

  By the way, in order to improve the efficiency of illuminating the imaging region (Ai), a method using an LED (light emitting diode) as a light source has been studied.

  FIG. 4 is a diagram illustrating a light source composed of a plurality of LEDs and illumination by the light source. FIG. 4A shows a single LED chip constituting the light source. FIG. 4B is a diagram for explaining the configuration of a light source composed of a plurality of LEDs. FIG. 4C is a diagram illustrating the illuminance distribution in the imaging region (Ai) illuminated by a light source composed of a plurality of LEDs.

  Here, as shown in FIG. 4A, an LED chip cut into a rectangle having a longitudinal direction (Vl) and a short direction (Vs) is used. As shown in FIG. 4B, a plurality of LED chips are aligned in the longitudinal direction (Vl) of the LED chips as shown in FIG. 4A to form a light source. The light source is such that the direction in which the plurality of LEDs are aligned (longitudinal direction of the plurality of LEDs) is the main scanning direction (Sx) of the one-dimensional imaging device, and the short direction of the plurality of LEDs is primary. It arrange | positions so that it may be a subscanning direction (Sy) of an original image pick-up element. The illumination target area (Ai) is illuminated using such a light source composed of a plurality of aligned LEDs.

  However, in such a method, the difference in the amount of light emission between the individual LEDs directly causes the illuminance unevenness of the illumination light by the light source. Here, shading correction is known as a technique for correcting slight illuminance unevenness. That is, before starting scanning by the one-dimensional image sensor, the entire white portion is read once in the main scanning direction (Sx), and the lightness of the actually read original is based on the lightness distribution in the read all white portions. The distribution can be corrected electrically. However, it is known that there is a variation of twice or more in the luminous efficiency of the LED for reasons of manufacturing the LED. As shown in FIG. 4C, when a plurality of LEDs having luminous efficiency with twice or more variations are used as a light source, an ideal illuminance distribution (Ideal_Di) that is flat in the imaging region (Ai) Thus, there are a portion illuminated with a higher illuminance h1 and a portion illuminated with a lower illuminance h2. The ratio of the illuminance h1 to the illuminance h2 may be twice or more. Such fluctuations in the illuminance distribution (Actual_Di) frequently occur throughout the plurality of LEDs. Therefore, in order to eliminate the fluctuations in the illuminance distribution (Actual_Di), an electrical amplifier is used and a one-dimensional imaging device is used. The obtained signal is subjected to a change in amplification factor of more than twice. As a result, the signal for the portion illuminated with a lower illuminance becomes a signal containing magnitude noise, which degrades the quality of the read signal. On the other hand, it is also conceivable to form a light source by selectively using a plurality of LEDs with little or no variation in luminous efficiency. However, selecting a plurality of LEDs with little or no variation in luminous efficiency greatly reduces the yield of a light source composed of a plurality of LEDs, resulting in several times the cost increase.

A first object of the present invention is to provide an original illuminating apparatus capable of illuminating an original with higher efficiency by light emitted from a light source.

A second object of the present invention is to provide an image reading device that reads an image of a document illuminated by a document illumination device capable of illuminating the document with light emitted from a light source with higher efficiency. .

The document illumination device according to claim 1 of the present application is
In a document illumination device that illuminates a document by superimposing light emitted from a plurality of light sources arranged in a first direction on the document surface,
A lens array provided corresponding to each of a plurality of light beams emitted from each of the plurality of light sources, and having a positive refractive power in the first direction and perpendicular to the first direction. A first lens having no refractive power in two directions, a focal length is F, and the first lens and the document surface are disposed at a position separated from the document surface by a focal length F; A second lens having no refractive power in the first direction and having a positive refractive power in the second direction, and each of the plurality of light sources emits light for each color of red, green, and blue A set of light emitting light sources that are covered with a hood lens composed of a convex lens with a convex surface facing the document surface on which the document is placed;
The focal length of the hood lens is f0, and the distance a from the red, green, and blue light emitting sources to the principal point to the hood lens is arranged to be equal to the focal length f0. The optical axis of the light beam emitted from the green light source among the red, green, and blue light sources is configured to coincide with the optical axis of the hood lens ,
The plurality of light sources arranged in the first direction are such that the central portion in the first direction is closest to the original surface, and further away from the original surface with the light source from the central portion toward the peripheral portion. Arranged in the
The focal lengths f0 of the hood lenses provided in the individual light sources are all the same, and each lens focal length f1 in the lens array that is the first lens changes according to the arrangement in the first direction, The relationship between the focal length f1 of the first lens corresponding to the light source at the center in the first direction and the focal length f0 of the hood lens is:
f0> f1, and f0 = f1 as it goes from the central part to the peripheral part, and then f0 <f1.
The document illumination device according to claim 2 of the present application is
In a document illumination device that illuminates a document by superimposing light emitted from a plurality of light sources arranged in a first direction on the document surface,
A lens array provided corresponding to each of a plurality of light beams emitted from each of the plurality of light sources, and having a positive refractive power in the first direction and perpendicular to the first direction. A first lens having no refractive power in two directions, a focal length is F, and the first lens and the document surface are disposed at a position separated from the document surface by a focal length F; A second lens having no refractive power in the first direction and having a positive refractive power in the second direction, and each of the plurality of light sources emits light for each color of red, green, and blue A set of light emitting light sources that are covered with a hood lens composed of a convex lens with a convex surface facing the document surface on which the document is placed;
The focal length of the hood lens is f0, and the distance a from the red, green, and blue light emitting sources to the principal point to the hood lens is arranged to be equal to the focal length f0. The optical axis of the light beam emitted from the green light source among the red, green, and blue light sources is configured to coincide with the optical axis of the hood lens,
The plurality of light sources arranged in the first direction are all arranged at an equal distance from the document surface, and the focal lengths f0 of the hood lenses provided in the individual light sources are all the same. The focal length f1 of each lens in the lens array which is the first lens changes according to the arrangement in the first direction, and the first lens corresponding to the light source at the center in the first direction The focal length f1 of the hood lens and the focal length f0 of the hood lens are f0> f1, passing through f0 = f1 from the center to the periphery, and then f0 <f1, For the plurality of light sources excluding the light source arranged in the center in the direction and the light sources arranged at both ends in the first direction, the optical axis of each light source is arranged in the center in the first direction. A prism is disposed immediately after the first lens so as to be inclined outward with respect to the optical axis of the light source.

The document illumination device according to claim 3 of the present application is the document illumination device according to claim 1 or 2 , wherein side mirrors are arranged on both side surfaces in the first direction of the first lens, and the side surface is disposed. The mirror is provided from both side surfaces of the hood lens in the first direction to both side surfaces of the second lens in the first direction.

An image reading apparatus according to a fourth aspect of the present invention is an image reading apparatus that illuminates a document by the document illumination device according to any one of the first to third aspects, and is scattered from the illuminated document. Alternatively, the imaging optical system includes an imaging optical system that forms an image of the reflected light, and an imaging device that captures an image formed by the imaging optical system.

According to the first to third aspects of the present invention, it is possible to provide a document illuminating device capable of illuminating a document with higher efficiency by light emitted from a light source.

According to the invention described in claim 4 of the present application, there is provided an image reading device that reads an image of an original illuminated by an original illumination device capable of illuminating the original with higher efficiency by light emitted from a light source. can do.

(A) And (b) is the schematic of a general image reading apparatus, and sectional drawing of the image reading apparatus in the subscanning direction, respectively. FIG. 6 is a diagram for explaining one of the problems related to illumination of a document in the image reading apparatus. It is a figure explaining another problem regarding illumination of the document in an image reading device. It is a figure explaining the illumination by the light source comprised by several LED, and the light source. It is a figure explaining the example of the illumination method by the 1st Example of this invention, and an illuminating device. It is a figure explaining the example of the image reading apparatus by the 2nd Example of this invention. It is a figure explaining the example of the image reading apparatus by the 3rd Example of this invention. It is a figure explaining the modification of the image reading apparatus by 3rd Example of this invention. It is a figure explaining the means to convert the light beam which diffuses from LED using a paraboloid mirror into parallel light. It is a figure explaining the means to convert the light beam diffused from LED into parallel light using a convex lens. It is a figure explaining one example of the illuminating device by the 4th Example of this invention. It is a figure explaining another example of the illuminating device by the 4th Example of this invention. It is a figure explaining one example of the illuminating device by the 4th Example of this invention, and an image reading apparatus. It is a figure explaining another example of the illuminating device by 4th Example of this invention, and an image reading apparatus. It is a figure explaining the example of the illuminating method by the 5th Example of this invention, and an illuminating device. It is a figure explaining the example of the illuminating method and image reading apparatus by the 6th Example of this invention. It is a figure explaining one example of the illumination method by the 7th Example of this invention, and an illuminating device. It is a figure explaining another example of the illuminating device by the 7th Example of this invention. It is a figure explaining the example of the illuminating device by the 8th Example of this invention. It is a figure explaining the example of the image reading apparatus by the 9th Example of this invention. It is a figure explaining the example of the image reading apparatus by the 10th Example of this invention. It is a figure explaining the relationship between the illumination intensity distribution in the imaging region in the image reading apparatus using a reduction optical system, and the relative brightness of the reduction optical system on CCD. It is a figure explaining the method to determine the arrangement | positioning space | interval of the several light source which illuminates an imaging region so that the relative brightness of the image imaged on a one-dimensional CCD becomes fixed. It is a figure explaining the specific arrangement | positioning of the several light source which illuminates the imaging target area | region so that the relative brightness of the image imaged on a one-dimensional CCD becomes fixed. A specific example of the relative brightness of an image formed on a one-dimensional CCD by an imaging lens in an imaging target area illuminated at a constant illuminance, and the relative brightness of an image formed on the one-dimensional CCD is constant. It is a figure which shows the specific example of target illuminance distribution (request | required illuminance distribution) in the case of illuminating an imaging object area | region like this. It is a figure which shows the result simulated toward the target relative illumination intensity which illuminates an illumination object area | region (imaging object area | region). It is a conceptual diagram for implement | achieving the illuminating device which adjusts the illumination intensity distribution of the light which illuminates an imaging region to the characteristic of 1 / cos < ⁴ > (theta) by adjusting the space | interval of several light sources. It is a figure explaining the specific arrangement | positioning of the several light source which illuminates the imaging target area | region so that the relative brightness of the image imaged on a one-dimensional CCD becomes fixed. It is a figure which shows the simulation result about the relative illumination intensity in the 12th actual example of this invention. It is a conceptual diagram for realizing an illuminating device that matches the illuminance distribution of the light that illuminates the imaging region with the 1 / cos ⁴ θ characteristic by adjusting the distance from each of the plurality of light sources to the imaging region. It is a figure explaining the example of the method of changing the radiation characteristic of the light discharge | released from a light source. It is a figure explaining another example of arrangement | positioning of the several light source which illuminates an imaging region so that the relative illumination intensity of the image imaged on a one-dimensional CCD becomes fixed. It is a conceptual diagram for realizing an illuminating device that matches the illuminance distribution of light that illuminates an imaging region with the 1 / cos ⁴ θ characteristic by adjusting the radiation characteristics of light emitted from a plurality of light sources. It is a conceptual diagram for realizing an illuminating device that approximates the illuminance distribution of light that illuminates the imaging region to the characteristic of 1 / cos ⁴ θ by adjusting the distance from each of the plurality of light sources to the imaging region. It is a figure explaining the specific arrangement | positioning of the several light source which illuminates the imaging target area | region so that the relative brightness of the image imaged on a one-dimensional CCD becomes fixed. By adjusting both the distance from each of the plurality of light sources to the imaging region and adjusting the radiation characteristics of the light emitted from the plurality of light sources, the illuminance distribution of the light that illuminates the imaging region is changed to the 1 / cos ⁴ θ characteristic. It is a conceptual diagram for implement | achieving the illuminating device made to correspond. It is a figure explaining the specific arrangement | positioning of the several light source which illuminates the imaging target area | region so that the relative brightness of the image imaged on a one-dimensional CCD becomes fixed. It is a figure which shows the simulation result about the difference of the relative illumination intensity in the 16th actual example of this invention, and target illumination intensity distribution. FIG. 4 is a conceptual diagram for realizing an illumination device that adjusts the illumination optical axis angle of light emitted from a plurality of light sources to match the illuminance distribution of the light that illuminates the imaging region with the 1 / cos ⁴ θ characteristic. is there. It is a figure explaining forming a virtual light source from a light source using a concave cylinder lens. It is a figure explaining the optical component which can be used for embodiment and the Example of this invention. It is a figure explaining the optical component which can be used for embodiment and the Example of this invention.

  Next, embodiments of the present invention will be described with reference to the drawings.

  Embodiments described herein relate generally to a document surface illumination method, a (document) illumination device, and an image reading apparatus using the same.

Embodiments of the present invention include, for example, an illumination method and apparatus for irradiating a document surface of a copying machine or a facsimile, a solid-state imaging device mounted on a digital PPC (plain paper copying machine), a connection The present invention relates to an image reading device (such as a film scanner and a handy scanner) equipped with an image lens and an illumination device, and an illumination device for the image reading device.

  In the first embodiment of the present invention, scattered light from a document surface illuminated by light from a light source is imaged on a photoconductor or an image sensor by an imaging lens, and the image formation target position in the image on the document surface is detected. The image formation target position on the document surface is sequentially moved in a direction (sub-scanning direction) perpendicular to the direction along the one-dimensional image (main scanning direction). In a document surface illumination method for an image forming apparatus that forms a two-dimensional image, a plurality of light sources are arranged at least in a direction corresponding to a direction along the one-dimensional image (main scanning direction), and emitted from the plurality of light sources. In the document surface illumination method for an image forming apparatus, the light flux of the light is diffused in a direction along the one-dimensional image of the document surface in a range that is at least twice the interval between adjacent light sources.

  In the second embodiment of the present invention, scattered light from a document surface illuminated by light from a light source is imaged on a photoconductor or an image sensor by an imaging lens, and the image formation target position in the image on the document surface is detected. The image formation target position on the document surface is sequentially moved in a direction (sub-scanning direction) perpendicular to the direction along the one-dimensional image (main scanning direction). In a document surface illumination method for an image forming apparatus that forms a two-dimensional image, a plurality of light sources are arranged at least in a direction corresponding to a direction along the one-dimensional image (main scanning direction), and emitted from the plurality of light sources. In the direction along the one-dimensional image of the document surface, and at least part of the light beam emitted from the plurality of light sources is To a one-dimensional image of a surface In Tsu direction (main scanning direction) perpendicular to direction (sub-scanning direction), an original surface illumination method for an image forming apparatus which comprises causing outlined focusing.

  In the third embodiment of the present invention, the light emitting means, the imaging means for forming an image on the image pickup device with the scattered light from the original surface illuminated by the light generated from the light emitting means, and the one-dimensional image in the image on the original surface are read. Image reading using a reading unit and a moving unit that sequentially moves the reading position of the reading unit in a direction (sub-scanning direction) perpendicular to the direction (main scanning direction) along the one-dimensional image. In the illuminating device for an apparatus, at least a plurality of light emitting means arranged in a direction corresponding to a direction along the one-dimensional image (main scanning direction), and a light beam generated from the plurality of light emitting means An illuminating device for an image reading apparatus, comprising: a light diffusing unit that diffuses in a direction along a one-dimensional image in a range that is twice or more the interval between adjacent light emitting units.

  In the third embodiment of the present invention, preferably, the pair of reflecting mirrors are arranged in parallel so as to sandwich a plurality of light emitting means arranged in a direction corresponding to at least a direction along the one-dimensional image (main scanning direction). Placed in.

  In the third embodiment of the present invention, preferably, the light diffusion means is a cylinder lens (or a cylindrical lens).

  In the third embodiment of the present invention, preferably, a parabolic mirror in which the position of the light source in each of the plurality of light emitting means is a focal position is arranged so as to correspond to each of the plurality of light emitting means.

  In the third embodiment of the present invention, preferably, an ellipsoidal mirror in which the position of the light source in each of the plurality of light emitting means is the position of one focal point is arranged so as to correspond to each of the plurality of light emitting means. .

  In the third embodiment of the present invention, preferably, a convex lens corresponding to each of the plurality of light emitting means is disposed.

  In the third embodiment of the present invention, it is preferable that at least a part of light beams emitted from a plurality of light sources is a direction (sub scanning direction) perpendicular to a direction (main scanning direction) along the one-dimensional image of the document surface. In the scanning direction), light focusing means for roughly focusing is arranged.

  In the third embodiment of the present invention, preferably, the light emitting means is a light emitting diode (LED).

  In the fourth embodiment of the present invention, scattered light from a document surface illuminated by light from a light source is imaged on an image sensor by an imaging lens, and a one-dimensional image at an image reading position in an image on the document surface The image reading position on the document surface is sequentially moved in the direction (sub-scanning direction) perpendicular to the reading direction (main scanning direction) of the one-dimensional image and the reading of the one-dimensional image is repeated. In the image reading apparatus for reading a two-dimensional image in the above, a plurality of light sources arranged in a direction corresponding to at least a direction (main scanning direction) along the one-dimensional image, and arranged to correspond to the plurality of light sources The light flux emitted from a plurality of light sources is diffused in a range along the one-dimensional image of the document surface in a range that is at least twice the interval between adjacent light sources, and is superimposed on the document surface. An image reading apparatus characterized by having a plurality of lenses (illumination lens) to.

  In the fifth embodiment of the present invention, scattered light from a document surface illuminated by light from a light source is imaged on an image sensor by an imaging lens, and is one-dimensional at an image formation target position in an image on the document surface. By reading the image, sequentially moving the image formation target position on the document surface in the direction (sub-scanning direction) perpendicular to the direction of reading the one-dimensional image (main scanning direction), and repeating the reading of the one-dimensional image, An image reading apparatus that reads a two-dimensional image of the image of the above-mentioned image has an illumination device according to the third embodiment of the present invention.

  In the sixth embodiment of the present invention, scattered light from a document surface illuminated by light from a light source is imaged on an image sensor by an imaging lens, and is one-dimensional at an image formation target position in an image on the document surface. By reading the image, sequentially moving the image formation target position on the document surface in the direction (sub-scanning direction) perpendicular to the direction of reading the one-dimensional image (main scanning direction), and repeating the reading of the one-dimensional image, In an image reading apparatus that reads a two-dimensional image in the image of the image, a plurality of light sources arranged in a direction corresponding to at least a direction (main scanning direction) along the one-dimensional image, and a plurality of light sources The luminous flux of the light emitted from the plurality of light sources is diffused in a range along the one-dimensional image of the document surface in a range that is equal to or larger than the interval between adjacent light sources, and is superimposed on the document surface. In an image reading apparatus having a plurality of lenses (illumination lenses), the plurality of light sources has an illuminance distribution characteristic of light illuminating the document surface at the image formation target position connected to the image sensor. The image reading apparatus is arranged so as to be roughly opposite to a lightness distribution characteristic of an image formed by an image lens.

  In the image reading apparatus according to the sixth embodiment of the present invention or the illuminating device for the image reading apparatus according to the sixth embodiment of the present invention, preferably, the interval between the plurality of light sources is an image formation target position. The distribution characteristic of the illuminance of the light illuminating the original surface on the original surface is set so as to be approximately opposite to the distribution characteristic of the brightness of the image formed on the image sensor by the imaging lens.

  In the image reading apparatus according to the sixth embodiment of the present invention or the illuminating device for the image reading apparatus according to the sixth embodiment of the present invention, it is preferable that the distance from the document surface to the plurality of light sources is image formation. The distribution characteristic of the illuminance of the light that illuminates the document surface on the document surface at the target position is set so as to be approximately opposite to the distribution characteristic of the brightness of the image formed by the imaging lens on the image sensor.

  In the image reading apparatus according to the sixth embodiment of the present invention or the illuminating device for the image reading apparatus according to the sixth embodiment of the present invention, preferably, the divergence angles of light beams emitted from a plurality of light sources are The distribution characteristics of the illuminance of the light illuminating the document surface at the image formation target position are set so as to be approximately opposite to the brightness distribution characteristics of the image formed by the imaging lens on the image sensor. The

  In the image reading apparatus according to the sixth embodiment of the present invention or the illuminating device for the image reading apparatus according to the sixth embodiment of the present invention, the orientation of the optical axes of the plurality of light sources depends on the original at the image forming target position. The distribution characteristic of the illuminance of the light illuminating the document surface on the surface is set so as to be approximately opposite to the distribution characteristic of the brightness of the image formed on the image sensor by the imaging lens.

  The “illumination device for the image reading device” includes a plurality of light sources arranged in a direction corresponding to at least a direction along the one-dimensional image (main scanning direction) used in the image reading device. Means an illuminating device that illuminates the document surface with light from the light source.

  In the image reading apparatus according to the sixth embodiment of the present invention or the illumination apparatus for the image reading apparatus according to the sixth embodiment of the present invention, a plurality of intervals between a plurality of light sources and a plurality of images from the document surface are used. A combination of at least two of the distance to the light source, the divergence angle of the luminous flux of the light emitted from the plurality of light sources, and the direction of the optical axis of the plurality of light sources (for example, the distance from the document surface to the plurality of light sources and the plurality of light sources) The divergence angle of the luminous flux of the light emitted from the light source), the distribution characteristics of the illuminance of the light that illuminates the document surface at the image formation target position, and the image of the image formed by the imaging lens on the image sensor. You may set so that it may be roughly reverse to the brightness distribution characteristic.

  In the embodiment of the present invention, examples of the illumination target include a sheet original and a book original in which a plurality of sheet originals such as a book and a notebook are bound. Further, the irradiated surface is a surface having a certain area.

  According to one embodiment of the present invention, a plurality of light sources (or light emitting means) are arranged in a direction corresponding to at least a direction along the one-dimensional image (main scanning direction), and light emitted from the plurality of light sources. When illuminating a wider area on the document surface using multiple light sources by diffusing the light flux in the direction along the one-dimensional image of the document surface to a range that is at least twice the interval between adjacent light sources Even so, it is possible to illuminate the document surface so as to reduce the difference in the amount of light emission among the plurality of light sources (or light emitting means). In other words, it is possible to illuminate the document surface so as to reduce unevenness in illuminance in the illuminated area of the document surface. Therefore, it is possible to illuminate the document surface more uniformly or with higher efficiency in the direction along the one-dimensional image of the document surface. As a result, a high-quality image can be obtained from the illuminated document surface.

  In addition, according to one embodiment of the present invention, the light flux emitted from the plurality of light sources is a direction (sub-scanning direction) perpendicular to the direction along the one-dimensional image (main scanning direction) of the document surface. In FIG. 2, the efficiency of illuminating the document surface can be improved by roughly focusing. As a result, energy required for illuminating the original surface can be reduced (energy saving).

  Furthermore, according to one embodiment of the present invention, the reflecting mirror, the cylinder lens (or cylindrical lens), the parabolic mirror, the elliptical mirror, and the convex lens are obtained by plastic molding means. Therefore, the cost of the illumination device or the image reading device can be reduced.

  Also, according to one of the embodiments of the present invention, when a light emitting diode (LED) is used as a light source, the light source can be driven by a low-voltage DC power source, so that the lighting circuit of the light source can be very easily It can be provided. As a result, the cost of the illumination device or the image reading device can be reduced.

  Further, according to one of the embodiments of the present invention, the plurality of light sources has an illuminance distribution characteristic of light illuminating the document surface at the image forming target position, and is imaged on the image sensor by the imaging lens. Since it is arranged so as to be roughly opposite to the brightness distribution characteristic of the image to be displayed, the amount of light emitted from a plurality of light sources is blocked or discarded without illuminating the document surface Alternatively, the brightness distribution of the image formed by the imaging lens in the image sensor can be made more uniform while being eliminated. As a result, it is possible to illuminate the document with higher efficiency with the light emitted from the light source, and it is possible to reduce the energy required to illuminate the document surface (energy saving).

  According to one of the embodiments of the present invention, the interval between the plurality of light sources is such that the distribution characteristic of the illuminance of the light illuminating the document surface at the image forming target position is imaged on the image sensor. Since it is set so as to be roughly opposite to the lightness distribution characteristics of the image formed by the lens, the light emitted from a plurality of light sources is blocked or discarded without illuminating the document surface. It is possible to reduce or eliminate the amount and make the illuminance distribution of the image formed by the imaging lens in the image sensor more uniform. As a result, it is possible to illuminate the document with higher efficiency with the light emitted from the light source, and it is possible to reduce the energy required to illuminate the document surface (energy saving).

  Further, according to one of the embodiments of the present invention, the distance from the document surface to the plurality of light sources is the distribution characteristic of the illuminance distribution of the light that illuminates the document surface at the image formation target position. Since it is set so as to be roughly opposite to the brightness distribution characteristic of the image formed by the imaging lens, it is blocked or discarded without illuminating the document surface among the light emitted from the plurality of light sources. It is possible to reduce or eliminate the amount of light generated and to make the illuminance distribution of the image formed by the imaging lens in the image sensor more uniform. As a result, it is possible to illuminate the document with higher efficiency with the light emitted from the light source, and it is possible to reduce the energy required to illuminate the document surface (energy saving).

  Further, according to one of the embodiments of the present invention, the divergence angle of light beams emitted from a plurality of light sources is determined by the distribution characteristic of the illuminance of light that illuminates the document surface at the image formation target position. Since it is set so as to be roughly opposite to the lightness distribution characteristic of the image formed by the imaging lens on the image sensor, it is blocked without illuminating the original surface of the light emitted from a plurality of light sources. It is possible to reduce or eliminate the amount of light that is lost or discarded, and to make the illuminance distribution of the image formed by the imaging lens in the image sensor more uniform. As a result, it is possible to illuminate the document with higher efficiency with the light emitted from the light source, and it is possible to reduce the energy required to illuminate the document surface (energy saving).

  Further, according to one embodiment of the present invention, the orientation of the optical axes of the plurality of light sources is determined by the distribution characteristics of the illuminance distribution of the light that illuminates the document surface at the image formation target position. Light that is set so as to be roughly opposite to the lightness distribution characteristics of the image formed by the image lens, so that light emitted from a plurality of light sources is blocked or discarded without illuminating the document surface As a result, the illuminance distribution of the image formed by the imaging lens in the image sensor can be made more uniform. As a result, it is possible to illuminate the document with higher efficiency with the light emitted from the light source, and it is possible to reduce the energy required to illuminate the document surface (energy saving).

  According to one embodiment of the present invention, the distance between the plurality of light sources, the distance from the document surface to the plurality of light sources, the divergence angle of the luminous flux of the light emitted from the plurality of light sources, and the plurality A combination of at least two of the directions of the optical axes of the light sources (for example, the distance from the document surface to the plurality of light sources and the divergence angles of the light beams emitted from the plurality of light sources) at the position where the image is formed By setting the illuminance distribution characteristic of the light that illuminates the document surface on the surface to be roughly opposite to the distribution characteristic of the brightness of the image formed by the imaging lens on the image sensor, it is possible to To reduce or eliminate the amount of emitted light that is blocked or discarded without illuminating the document surface, and to make the illuminance distribution of the image formed by the imaging lens in the image sensor more uniform Made possible . As a result, it is possible to illuminate the document with higher efficiency with the light emitted from the light source, and it is possible to reduce the energy required to illuminate the document surface (energy saving).

[Example]
Next, examples according to the embodiment of the present invention will be described. In the illumination method and the illumination device according to the embodiment of the present invention, a conventional (image of a document surface is directly projected onto a photoreceptor to form a latent image on the photoreceptor, and the latent image is developed with black toner or color toner. In an embodiment of the present invention, an illumination method and an illumination apparatus used in an image reading apparatus generally called a digital copying machine or a scanner will be described. .

  FIG. 5 is a diagram for explaining an example of an illumination method and an illumination apparatus according to the first embodiment of the present invention. FIG. 5A is a top view of an example of a lighting device according to the first embodiment of the present invention, and FIG. 5B is a front view of the example of the lighting device according to the first embodiment of the present invention. is there. FIG. 5C is a diagram showing the illuminance distribution in the main scanning direction (Sx) on the illumination target surface (imaging region) (Ai) obtained by the example of the illumination method according to the first embodiment of the present invention. FIG. 5D is a diagram showing the illuminance distribution in the sub-scanning direction on the illumination target surface (imaging region) (Ai) obtained by the example of the illumination method according to the first embodiment of the present invention. .

  The illumination device according to the first embodiment of the present invention as shown in FIGS. 5A and 5B corresponds to the illumination lamp and the reflector in the conventional illumination device shown in FIGS. 1A and 1B. .

  First, the structure of the illuminating device by the 1st Example of this invention is demonstrated.

  As shown in FIGS. 5A and 5B, the illumination device according to the first embodiment of the invention includes a plurality of LEDs (1), a plurality of rotary parabolic mirrors (2a), and an illumination lens (3). And a focusing lens (4a), and a side mirror A (5a) and a side mirror B (5b).

  Each of the plurality of LEDs (1) is a light emitting diode chip and is used as a light source. In the illumination device according to the first embodiment of the present invention, n LEDs (1) (L1 to Ln) are arranged at equal intervals in the main scanning direction (Sx).

  The plurality of rotary parabolic mirrors (2a) are respectively arranged corresponding to the plurality of LEDs (1), and the light emitting surface of the LED (1) is arranged at the focal position of the rotary parabolic mirror (2a). Thus, most of the light diffused from the LED is converted into parallel light. The plurality of rotary parabolic mirrors (2a) are used as a first focusing means for focusing a light beam that diffuses at an angle of 180 ° from the light emitting surface of the LED (1) to the front surface side of the LED (1).

  The illumination lens (3) is a cylinder lens array in the illumination device of the first embodiment of the present invention. The illumination lens (3) diffuses the parallel light beam emitted from the rotary parabolic mirror (2a) in the main scanning direction (Sx), and is diffused by the illumination lens (3). (Ai) (Although it refers to the same part as the imaging region, when the illumination device is described, the imaging region is referred to as an illumination target surface or an illumination target region). Here, the individual lenses constituting the cylinder lens array of the illumination lens (3) are completely or substantially the same cylinder lens, and the focal length of each cylinder lens is f, and the arrangement direction of the cylinder lenses ( Let m be the width of each cylinder lens in the main scanning direction (Sx). Moreover, the width m of each cylinder lens is equal to the space | interval of adjacent LED (1) in several LED (1). If the distance from the cylinder lens to the illumination target surface (imaging area) (Ai) is g, the illumination object illuminated by the light transmitted through the cylinder lens in the cylinder lens arrangement direction (main scanning direction (Sx)). The illumination range M on the surface (imaging area) (Ai) is

Is represented by In the illumination device of the first embodiment of the present invention, in the main scanning direction (Sx), the cylinder lens with respect to the width m of each cylinder lens, that is, the interval between adjacent LEDs (1) in the plurality of LEDs (1). The ratio (M / m) of the illumination range M on the illumination target surface (imaging region) (Ai) illuminated by the light that has passed through is twice or more. On the other hand, in the direction perpendicular to the arrangement direction of the cylinder lenses (main scanning direction (Sx)) (sub-scanning direction (Sy)), the cylinder lens is equivalent to a plane parallel plate, and therefore the paraboloid mirror (2a ) Is transmitted as parallel light.

  If the length of the illumination symmetry plane in the main scanning direction (Sx) is K, the width of the cylinder lens array in the main scanning direction (Sx) may also be K. The width of the cylinder lens in the main scanning direction (Sx) is preferably completely or substantially the same as the width of the paraboloid mirror (2a) in the main scanning direction (Sx). That is,

Where n is the number of cylinder lenses that make up the cylinder lens array.

  The focusing lens (4a) is a single cylinder lens, and is provided so as to focus the light transmitted through the illumination lens (3) onto the illumination target surface (imaging region) (Ai) in the sub-scanning direction (Sy). It is done. That is, the parallel light emitted from the rotary parabolic mirror (2a) is not diffused by the illumination lens (3) in the sub-scanning direction (Sy), but is illuminated by the focusing lens (4) (imaging target surface). The region (Ai) is sharply focused. Since the focusing lens (4) is equivalent to a plane-parallel plate in the main scanning direction (Sx), the light diffused by the illumination lens (3) is not focused by the focusing lens (4) and remains as it is. Spread. The focusing lens (4) can be easily substituted with a parabolic mirror having the same function as the focusing lens.

  In addition, the focusing lens (4) is not necessarily required in the illumination apparatus according to the first embodiment of the present invention, and the light transmitted through the illumination lens (3) is transmitted in the sub-scanning direction (Sy). The light may be applied to the illumination target surface (imaging region) (Ai) as parallel light. Further, the focusing lens (4) may be disposed at a position on the illumination target surface (imaging region) (Ai) side, or may be disposed on the illumination lens (3) side. Furthermore, the focusing lens (4) can be formed integrally with the illumination lens (3). In this case, the number of parts used for the lighting device can be reduced by using plastic molding means.

The side mirror A (5a) and the side mirror B (5b) are mirrors arranged on both sides of the cylinder lens array of the illumination lens (3). The side mirror A (5a) and the side mirror B (5b) are provided to irradiate the illumination target surface (imaging region) (Ai) with higher efficiency with the light emitted from the LED (1). In FIG. 5, the light emitted from the three LEDs (1) (L1, L2, and L3) is reflected by the side mirror A (5a) to the illumination target surface (imaging region) (Ai). Furthermore, the light emitted from the three LEDs (1) (Ln-2, Ln-1, and Ln) is reflected by the side mirror B (5b) to the illumination target surface (imaging region) (Ai). Thus, the side mirror A (5a) and the side mirror B (5b) have these six LEDs (1) as if they were arranged outside the lighting device. Since the light from (1) is reflected, a uniform illuminance distribution is obtained at the end of the illumination target surface (imaging region) (Ai) as in the central portion of the illumination target surface (imaging region) (Ai). It is done. (It is ideal to provide a side mirror from the cylinder lens array to the illumination target surface (imaging region) (Ai). However, in an actual image reading apparatus, a contact glass as a document table is avoided and the side surface mirror is provided. As a result, the illuminance at the end of the illumination target surface (imaging region) (Ai) is slightly lower than the illuminance at the center of the illumination target surface (imaging region) (Ai). Accordingly, the overall width of the illumination device in the main scanning direction (Sx) needs to be increased, but the overall width of the illumination device when the side mirror A (5a) and the side mirror B (5b) are provided. (The fluctuation amount of is very small with respect to the fluctuation amount of the entire width of the lighting device when the side mirror is not used.)
Next, a lighting method according to the first embodiment of the present invention using the lighting device according to the first embodiment of the present invention will be described.

  As shown in FIGS. 5A and 5C, in the main scanning direction (Sx), light emitted from one (L4) of the plurality of LEDs (1) is a parabolic mirror corresponding to L4. It is reflected by (2a) and emitted as approximately parallel light. The light emitted from the rotary paraboloid mirror (2a) corresponding to L4 enters the cylinder lens constituting the illumination lens (3) corresponding to L4. The light transmitted through the cylinder lens is once focused at the position of the focal length f of the cylinder lens, but is diffused at a distance exceeding the focal length f of the cylinder lens regardless of the presence or absence of the focusing lens (4). Thus, in the main scanning direction (Sx), the width of the luminous flux of the light emitted from L4 of the LED (1) is the size m of the cylinder lens, that is, the adjacent LEDs (1). It spreads from the size of the interval to M on the illumination target surface (imaging region) (Ai), and the illumination target surface (imaging region) (Ai) is irradiated. Here, when g is the distance from the principal point of the cylinder lens corresponding to one L4 of the LED (1) to the illumination target surface (imaging region) (Ai), the LED (1) in the main scanning direction (Sx) The expansion factor Q (= M / m) of the width of the luminous flux of light emitted from one L4 is

Is represented by In the illumination method according to the first embodiment of the present invention, the magnification Q of the width of the luminous flux of light emitted from one of the LEDs (1) in the main scanning direction (Sx), that is, adjacent LEDs ( The ratio of the width M of the light beam on the illumination target surface (imaging region) (Ai) to the size of the interval 1) is twice or more. In FIG. 5, Q is about 6.5.

  At this time, the illuminance distribution on the illumination target surface (imaging region) (Ai) due to only the light emitted from the L4 of the LED (1) is as shown by the thick line in FIG. 5C (Each_Di). ). That is, the illuminance on the axis (optical axis) passing through the center of the rotating paraboloid mirror (2a) corresponding to L4 and L4 of LED (1) is a peak, and is emitted from L4 as the distance from the optical axis increases. The illuminance due to the emitted light decreases. As a result, the illuminance distribution on the illumination target surface (imaging region) (Ai) caused by only the light emitted from L4 of the LED (1) depends on the position on the illumination target surface (imaging region) (Ai). Gives a highly variable illuminance distribution.

  However, the light emitted from L5 of LED (1) adjacent to L4 of LED (1) is caused by the light emitted from L4 of LED (1) on the illumination target surface (imaging region) (Ai). A similar illuminance distribution having a peak displaced by m in the main scanning direction (Sx) from the position of the peak of the illuminance distribution on the illumination target surface (imaging region) (Ai) is given. Moreover, the light emitted from each of L6 to Ln of the LED (1) also illuminates the illumination target surface (imaging region) (Ai) with the same illuminance distribution (Di). Here, on the illumination target surface (imaging area) (Ai), the light on the optical axis L4 of the LED (1) is emitted from the L1 of the LED (1) with a smaller amount of light, LED (1). An intermediate amount of light emitted from L2 of LED 2 and a greater amount of light emitted from L3 of LED (2). Further, here, on the illumination target surface (imaging region) (Ai), the light on the optical axis of L4 of LED (1) is approximately the same as the amount of light emitted from L3 of LED (1). A quantity of light emitted from L5 of LED (1), a quantity of light emitted from L6 of LED (1) that is comparable to the quantity of light emitted from L2 of LED (1), and LED ( 1) includes an amount of light emitted from L7 of LED (1) in the same amount as the amount of light emitted from L1.

  As a result, on the optical axis of L4 of LED (1), the light emitted from L1 to L7 of LED (1) is superimposed on the illumination target surface (imaging region) (Ai) and the illumination target surface (Imaging area) (Ai) is illuminated.

  In the illumination method according to the first embodiment of the present invention, an arbitrary point on the illumination target surface (imaging region) (Ai) is the number of LEDs obtained by rounding down the numbers after the decimal point of the Q value described above or Illumination is performed with light emitted from the number of LEDs (6 or 7 in FIG. 5) obtained by rounding up the number after the decimal point of the Q value described above. As a result, the illuminance distribution on the illumination target surface (imaging region) (Ai) becomes more uniform (flatter) (shows the concept of Total_Di).

  As shown in FIGS. 5B and 5D, in the sub-scanning direction (Sy), the light diffusing from each of the plurality of LEDs (1) is transmitted to each LED (1) as the first focusing means. ) Is converted into substantially parallel light by the rotating paraboloid mirror (2a), and passes through the illumination lens (3) as parallel light. When the focusing lens (4a) is not provided in the illumination device, the parallel light illuminates the illumination target surface (imaging region) (Ai) as parallel light as it is. In this case, in the sub-scanning direction (Sy), the illuminance distribution on the illumination target surface (imaging region) is the illuminance distribution (Each_Di) caused by the individual LEDs (1) as indicated by the solid line in FIG. ) And illuminance distribution (Total_Di) obtained by superimposing light emitted from the plurality of LEDs (1). That is, when the illumination device does not include the focusing lens (4a), the illuminance distribution on the illumination target surface (imaging region) (Ai) is a relatively broad illuminance distribution.

  On the other hand, when a sharp illuminance distribution is necessary on the illumination target surface (imaging region) (Ai) in the sub-scanning direction (Sy), the focusing lens (4a) as the second focusing means is used. When the illumination device does not include the focusing lens (4a), the illuminance distribution on the illumination target surface (imaging area) (Ai) in the sub-scanning direction (Sy) is a two-dot chain line in FIG. The illuminance distribution (Each_Di) resulting from the individual LEDs (1) as shown and the illuminance distribution (Total_Di) obtained by superimposing the light emitted from the plurality of LEDs (1). That is, when the illumination device includes the focusing lens (4a), the illuminance distribution on the illumination target surface (imaging region) (Ai) is a relatively sharp illuminance distribution.

  When an intermediate illuminance distribution between a relatively sharp illuminance distribution and a relatively broad illuminance distribution in the sub-scanning direction (Sy) is required on the illumination target surface (imaging region) (Ai). By setting the focal length of the focusing lens (4) so that the focal point of the focusing lens is away from the position of the illumination target surface (imaging region) (Ai), the illumination target surface (imaging region) (Ai) An illuminance distribution having an arbitrary width can be obtained. In this way, the illuminance distribution on the illumination target surface (imaging region) (Ai) is maintained substantially constant in the main scanning direction (Sx), and the illumination target surface (imaging region) in the sub-scanning direction (Sy). The illuminance distribution on (Ai) can be arbitrarily set to a sharp or broad illuminance distribution.

  Next, an image reading apparatus according to a second embodiment of the present invention provided with a first traveling body having the illumination device according to the first embodiment of the present invention will be described.

  FIG. 6 is a diagram for explaining an example of an image reading apparatus according to the second embodiment of the present invention.

  FIG. 6A is a top view of the image reading apparatus according to the second embodiment of the present invention using the illumination apparatus according to the first embodiment of the present invention, and FIG. 6B is the first view of the present invention. It is a front view of the image reading apparatus by 2nd Example of this invention using the illuminating device by this Example.

  6A shows a turning mirror 12 in addition to the illumination device according to the first embodiment of the present invention as shown in FIG. As shown by a two-dot chain line in FIG. 6B, when the illuminating device is arranged without bending the optical axis of the illuminating device, the light of the reading system that is the optical path of the reflected light from the imaging region (Ai). In order to avoid placing the illumination device on the axis (reading optical axis (AxR)), the entire optical axis (illumination optical axis (AxI)) of the illumination device is tilted from the reading optical axis (AxR). . Further, when the inclination angle θ of the illumination optical axis (AxI) with respect to the reading optical axis (AxR) is reduced, the size of the image reading device in the direction perpendicular to the contact glass (13) is increased. As indicated by the solid line in b), the illumination optical axis (AxI) can also be folded using the folding mirror (6). In this manner, the size of the image reading device in the direction perpendicular to the contact glass (13) can be reduced by arranging the illumination device in parallel to the surface of the contact glass (13). Note that the illumination device may or may not include the focusing lens (4a) depending on the target illuminance distribution in the imaging region (Ai) in the sub-scanning direction (Sy).

  FIG. 6C is a top view of the image reading apparatus according to the second embodiment of the present invention using a modification of the illumination apparatus according to the first embodiment of the present invention, and FIG. It is a front view of the image reading apparatus by 2nd Example of this invention using the modification of the illuminating device by 1st Example of this.

  In the illumination device shown in FIGS. 6C and 6D, a focusing mirror (4b) is used instead of the focusing lens (4a) shown in FIGS. 6A and 6B. The focusing mirror (4b) is a parabolic mirror having a focal point in the imaging region (Ai) in the sub-scanning direction (Sy), and a reflecting surface having no focusing function in the main scanning direction (Sx). It is a mirror like that. Moreover, since the focusing mirror (4b) can have the function of the folding mirror (12) shown in FIGS. 6 (a) and 6 (b), the number of components of the lighting device can be reduced and the contact glass (13 The size of the image reading device in the direction perpendicular to () can be reduced. The bending direction of the reading optical axis (AxR) may be any of the left and right directions in FIG.

  By adopting the configuration of the image reading apparatus as shown in FIG. 6, a plurality of LEDs (n is 10 or more in FIG. 6) in the imaging region (Ai) in the main scanning direction (Sx) of the image reading apparatus. Since the luminous flux emitted from the LED is superimposed and irradiated, the variation in the luminous efficiency of the plurality of LEDs is averaged, and the illuminance unevenness in the imaging region (Ai) is uniformed. Alleviated. When a generally manufactured LED is used as a light source, if an illuminating device is designed so that light beams emitted from five or more LEDs overlap using LEDs belonging to the same rank, the main scanning direction ( Irradiance unevenness in the entire imaging region (Ai) in Sx) can be suppressed to about 20%. Further, if the illumination device is designed so that light beams emitted from 10 or more LEDs overlap, the illuminance unevenness in the entire imaging region (Ai) in the main scanning direction (Sx) can be suppressed to less than 10%. Is also possible. Accordingly, by electrically correcting the illuminance unevenness in the imaging region (Ai), it is possible to reduce the noise of the image signal even in a place where the illuminance is low in the imaging region (Ai). Can be improved.

  Next, an image reading apparatus according to a third embodiment of the present invention that can improve the reading of the central portion of a book document will be described.

  FIG. 7 is a diagram for explaining an example of an image reading apparatus according to the third embodiment of the present invention. 7 (a), (b), (c), (d), (e) and (f) respectively show a third embodiment of the present invention which can improve the reading of the central portion of the book document. FIG.

  In the example of the image reading apparatus as shown in FIG. 7A, the sub-beam among the light beams transmitted through the focusing lens (4a) in the image reading apparatus as shown in FIGS. 6A and 6B. In the scanning direction, the light flux on the contact glass (13) side with respect to the illumination optical axis (AxI) is reflected to the imaging region (Ai) by the folding mirror A (6a) behind the reading optical axis (AxR). On the other hand, among the light beams transmitted through the focusing lens (4a), in the sub-scanning direction, the light beam closer to the turning mirror (12) than the illumination optical axis (AxI) is forward of the reading optical axis (AxR). Then, the light is reflected by the folding mirror B (6b) to the imaging region (Ai) (note that the light flux on the direction of the deflecting mirror (12) with respect to the illumination optical axis (AxI) is on the front side with respect to the reading optical axis (AxR). , Because it folds back, mirror A ( The size of a), can be reduced, the entire illumination device can be brought close to the reader optical axis (AxR) side.). Here, since the focal length of the focusing lens (4a) is the same for all the light beams transmitted through the focusing lens (4a), the arrangement of the folding mirrors A and B (6a, 6b) is changed to the focusing lens (4a). By adjusting so that the distance from the imaging area (Ai) to the imaging area (Ai) is constant, an illuminance distribution similar to that shown in FIG. 5A can be obtained. However, it is not necessary to make the distance from the focusing lens (4a) to the imaging region (Ai) common to all the light beams transmitted through the focusing lens (4a). When the distance from the focusing lens (4a) to the imaging region (Ai) is not common for all the light beams transmitted through the focusing lens (4a), the contact glass (13) side from the illumination optical axis (AxI) Mirrors A and B (so that the imaging region (Ai) is positioned between the focal position of the luminous flux and the focal position of the luminous flux on the side of the deflecting mirror (12) with respect to the illumination optical axis (AxI). It is preferable to set the arrangement of 6a and 6b).

  In the example of the image reading apparatus as shown in FIG. 7B, the sub-scanning of the light beam transmitted through the focusing lens (4a) is opposite to the image reading apparatus as shown in FIG. 7A. In the direction, the light flux on the contact glass (13) side with respect to the illumination optical axis (AxI) is reflected to the imaging region (Ai) by the folding mirror B (6b) on the front side with respect to the reading optical axis (AxR). Among the light beams transmitted through the focusing lens (4a), the light beam on the direction of the deflecting mirror (12) with respect to the illumination optical axis (AxI) is rearward of the reading optical axis (AxR) in the sub-scanning direction. Then, the light is reflected to the imaging area (Ai) by the folding mirror A (6a). Further, the light flux on the contact glass (13) side with respect to the illumination optical axis (AxI) is focused on the rear side (FB) with respect to the imaging region (Ai), and the deflecting mirror (12) with respect to the illumination optical axis (AxI). Is focused on the front side (FA) of the imaging area (Ai). In this case, the central portion of the original surface of the book document is irradiated with a light beam closer to the contact glass (13) than the illumination optical axis (AxI), and the direction mirror (12) is further than the illumination optical axis (AxI). The light beam on the side can be diffused without being focused on the document surface of the book document, and can be irradiated to the book document. As a result, it is possible to irradiate the central portion of the book document with a good balance of light, and to prevent or reduce reading of the central portion of the book document as a black image.

  In the example of the image reading apparatus as shown in FIG. 7C, in the image reading apparatus as shown in FIGS. 6C and 6D, out of the light flux reflected by the focusing mirror, in the sub-scanning direction. , The light flux on the contact glass (13) side from the illumination optical axis (AxI) is reflected to the focusing mirror B (4b2) by the folding mirror (6) on the front side from the reading optical axis (AxR) and focused. While reflected by the mirror B (4b2) to the imaging region (Ai), out of the light flux reflected by the focusing mirror, in the sub-scanning direction, it is closer to the direction of the mirror (12) than the illumination optical axis (AxI). Is reflected to the imaging region (Ai) by the focusing mirror A (4b1) behind the reading optical axis (AxR). Here, the focusing mirror A (4b1) and the focusing mirror B (4b2) are mirrors that are parallel planes in the main scanning direction and paraboloids that are focused on the imaging region (Ai) in the sub-scanning direction. It is. In addition, since it is not necessary to reflect the light beam closer to the direction changing mirror (12) than the illumination optical axis (AxI) by the focusing mirror A (4b1), the size of the focusing mirror A (4b1) is reduced. Can do. In FIG. 7C, both the luminous flux on the contact glass (13) side with respect to the illumination optical axis (AxI) and the luminous flux on the direction changing mirror (12) side with respect to the illumination optical axis (AxI) are captured in the imaging region (Ai). Depending on the type of document surface and the required illuminance distribution, the focal lengths of the focusing mirror A (4b1) and the focusing mirror B (4b2) in the sub-scanning direction are set appropriately. It is also possible to focus independently before and after the imaging area (Ai).

  In the example of the image reading apparatus as shown in FIG. 7D, in the image reading apparatus as shown in FIG. 7C, the substantially parallel light on the contact glass (13) side with respect to the illumination optical axis (AxI). The light beam is reflected as a parallel light beam to the imaging region (Ai) by the folding mirror (6) in front of the reading optical axis (AxR) without using the focusing mirror B (4b2) in the sub-scanning direction. In this case, in the sub-scanning direction, the illuminance distribution in the imaging region (Ai) by the substantially parallel light beam on the contact glass (13) side from the illumination optical axis (AxI) shows a broad distribution, and the illumination light The illuminance distribution in the imaging region (Ai) by the light flux on the direction of the deflecting mirror (12) with respect to the axis (AxI) shows a sharp distribution.

  The example of the image reading apparatus as shown in FIGS. 7E and 7F is an example of an image reading apparatus that uses neither a focusing lens nor a focusing mirror. In the example of the image reading apparatus as shown in FIG. 7E, the light beam on the side of the contact glass (13) with respect to the illumination optical axis (AxI) out of the substantially parallel light beam transmitted through the illumination lens is read light. The light beam reflected from the rear side of the axis (AxR) to the imaging region (Ai) and reflected on the direction of the deflecting mirror (12) from the illumination optical axis (AxI) is reflected from the imaging region (AxR) to the front side of the reading optical axis (AxR). Reflect to Ai). Similarly, in the example of the image reading apparatus as shown in FIG. 7F, the light flux on the contact glass (13) side from the illumination optical axis (AxI) out of the substantially parallel light flux transmitted through the illumination lens. The light beam reflected on the imaging region (Ai) in front of the reading optical axis (AxR) and reflected on the deflecting mirror (12) side of the illumination optical axis (AxI) is rearward of the reading optical axis (AxR). Reflected to the imaging area (Ai). In these cases, in the image reading apparatus using the focusing lens or the focusing mirror, the light use efficiency of the illuminating device is reduced, but the illuminance distribution in the imaging region (Ai) is broad, and the central portion of the book document Can be prevented or reduced more effectively as a black image.

  FIG. 7 shows an example of the arrangement of the focusing lens, the folding mirror, and the focusing mirror in the image reading apparatus. However, the arrangement of the focusing lens, the folding mirror, and the focusing mirror is arbitrary, as shown in FIG. It is not limited to. In the example of the image reading apparatus shown in FIG. 7, the light beam is divided in half before and after the illumination optical axis (AxI). However, the ratio of the light beam division is not limited to 5: 5, and imaging is performed. It is arbitrarily set according to the degree of focusing in the area (Ai) or the type of document, and may be 6: 4 or 3: 7, for example.

  FIG. 8 is a diagram for explaining a modification of the image reading apparatus according to the third embodiment of the present invention. FIG. 8A is a diagram for explaining a first modification of the image reading apparatus according to the third embodiment of the present invention, and FIG. 8B is an image reading according to the third embodiment of the present invention. It is a figure explaining the 2nd modification of an apparatus.

  In the example of the image reading apparatus shown in FIG. 6, the illuminating device main body is arranged on the front side or the rear side with respect to the reading optical axis (AxR) to illuminate the imaging region (Ai), and the image shown in FIG. In the example of the reading device, the light flux is divided into two, and the imaging region (Ai) is illuminated from both the front side and the rear side of the reading optical axis (AxR). On the other hand, in the example of the image reading apparatus shown in FIG. 8, two illuminating device main bodies are arranged on both the front side and the rear side of the reading optical axis (AxR), and the two illuminating device main bodies are used. The imaging area (Ai) is illuminated from both the front side and the rear side of the reading optical axis (AxR). In the example of the image reading apparatus as indicated by the solid line in FIG. 8A, the two illuminating device bodies are read without bending the illumination optical axes (AxI) of the two illuminating device bodies including the focusing lens (4a). It arrange | positions diagonally with respect to an optical axis (AxR). In this case, the size of the image reading device in the direction parallel to the surface of the contact glass (13) can be reduced. However, as indicated by the two-dot chain line in FIG. 8A, the illuminating device main body can be arranged in parallel to the surface of the contact glass (13) using the folding mirror (6). In this case, the size of the image reading device in the direction perpendicular to the surface of the contact glass (13) can be reduced.

  In the example of the image reading apparatus as shown in FIG. 8B, two illuminating device bodies including a focusing mirror (4b) and a folding mirror (6) which are parabolic mirrors are used.

  Also in the example of the image reading apparatus as shown in FIG. 8, one or both of the two illuminating device bodies may not include either the focusing lens or the focusing mirror, as shown in FIG. Variations in the example of the image reading device can be applied.

  In the second or third embodiment of the present invention, the example of the configuration of the image reading apparatus provided with the illumination device on the first traveling body has been described.

  Next, in the illumination device according to the embodiment of the present invention, details of means for converting the light beam diffused from the LED into parallel light in the first focusing stage will be described.

  FIG. 9 is a diagram for explaining means for converting a light beam diffusing from an LED into parallel light using a rotating parabolic mirror. FIG. 9A is a front view of a light source including an LED and a rotating parabolic mirror, and FIG. 9B is a side view of the light source including an LED and a rotating parabolic mirror.

  As shown in FIG. 9, the x axis, the y axis, and the z axis are defined, and the center of the light emitting surface of the LED (1) is arranged at the intersection of the x axis, the y axis, and the z axis. The focal length of the rotating paraboloid mirror (2a) is f, and the rotating paraboloid of the rotating paraboloid mirror (2a)

Is a paraboloid obtained by rotating the parabola represented by x around the x axis. The center of the light emitting surface of the LED (1) is disposed at the focal position (Pf) of the paraboloid. Here, the light emitting surface of the LED (1) faces the rotary parabolic mirror (2a). As shown in FIGS. 9A and 9B, the LED (1) is connected to the two electrodes (21) via the lead wire (22) and embedded in the transparent resin (23). .

  As indicated by a two-dot chain line in FIG. 9, the outer periphery of the rotary parabolic mirror (2a) may be circular, but the radiation vector (Vr) from the light emitting surface of the LED (1) in FIG. 9 (a). ), The intensity of the rotating paraboloid mirror (2a) in the vicinity of the x-axis is lower than that in the vicinity of the x-axis, so that the rotational parallax in the main scanning direction (Sx) (eg, z direction) In order to increase the density at which the object plane (2a) is arranged, the peripheral portion of the rotating paraboloid mirror (2a) in the main scanning direction (Sx) may be cut off (that is, the rotating paraboloid mirror (2a) is removed). When viewed from the side, the rotating parabolic mirror (2a) has an oval shape). Further, in order to reduce the size of the illumination device at the expense of a slight decrease in the illumination efficiency of the illumination device, the peripheral portion of the rotary parabolic mirror (2a) in the sub-scanning direction (Sy) (for example, the y direction) is You may cut out (that is, when the paraboloid mirror (2a) is viewed from the side, the paraboloid mirror (2a) has a square shape). Since the light emitting surface of the LED (1) has an area, there is only one place where light is emitted at the focal position of the rotating paraboloid, and all the light emitted at other positions is the focal position of the rotating paraboloid. It is off. That is, all the light emission vectors emitted from the focal position of the rotary parabolic mirror (2a) are parallel light, but all the light emission vectors emitted from other places are reflected by the rotary parabolic mirror (2a). Deviation from parallel light. The deviation increases as the distance from the focal position of the rotary parabolic mirror (2a) increases.

  FIG. 9 (c) shows a certain point in the vicinity of the optical axis at a certain distance of light emitted from a light source including a rotating paraboloid mirror and an LED as shown in FIGS. 9 (a) and 9 (b). It is a light distribution characteristic figure which shows the vector intensity | strength of the light which passes through (or comes toward a certain point) by a relative value. The horizontal axis in FIG. 9C represents the angle (°) from the optical axis of the parabolic mirror, and the vertical axis in FIG. 9C represents the strongest value of the intensity of the light vector passing through a certain point. It represents the relative radiation intensity RP (%) as a reference. The component (0 degree) parallel to the optical axis (x-axis) of the parabolic mirror is strongest, but there is also a component having an angle. (The amount decreases as the angle increases. The angle that falls to 50% is called the half width, which is ± 5 degrees in this example.)

  FIG. 10 is a diagram for explaining means for converting a light beam diffused from the LED into parallel light using a convex lens. FIG. 10A is a front view of a light source including an LED and a convex lens, and FIG. 10B is a side view of the light source including an LED and a convex lens.

  The light source including the LED and the convex lens shown in FIGS. 10A and 10B is called a cannonball type, and the LED (1) attached to the base 25 has a convex lens shape made of a resin material. Covered with a hood lens (24). The LED (1) is connected to the electrode (21) via the lead wire (22). Here, the center of the light emitting surface of the LED (1) is disposed at the focal position (Pf) of the hood lens (24) which is a convex lens. Further, the size of the lens of the hood lens (24) is determined so that the angle of light incident on the periphery of the convex lens shape as shown in FIG.

  As shown by a two-dot chain line in FIG. 10B, the outer periphery of the hood lens 24 may be circular, but the distribution of the radiation vector (Vr) from the light emitting surface of the LED 1 in FIG. As shown in FIG. 3, since the intensity of light passing through the peripheral portion of the hood lens (24) is low, the density of arranging the hood lens (24) in the main scanning direction (Sx) (for example, z direction) is increased. In addition, the peripheral portion of the hood lens (24) in the main scanning direction (Sx) may be cut off (that is, when the hood lens (24) is viewed from the side, the hood lens (24) has an oval shape. ). Further, even if the peripheral portion of the hood lens (24) in the sub-scanning direction (Sy) (for example, the y direction) is cut out in order to reduce the size of the lighting device at the expense of a slight decrease in the lighting efficiency of the lighting device. Good (ie, when the hood lens (24) is viewed from the side, the hood lens (24) has a square shape).

  Further, the entire side surface of the hood lens (24) is preferably a mirror surface. In this case, the light incident on the side surface of the hood lens (24) is reflected from the mirror surface by reflecting the light incident on the side surface of the hood lens (24) from the lens surface of the hood lens (24) (in the case of parallel light). Can be injected) However, the side surface of the hood lens (24) in the main scanning direction (Sx) (for example, the z direction) may be a non-mirror surface. In the main scanning direction (Sx) (z direction), light that escapes from the side surface of the hood lens can be effectively used by making it incident on the adjacent hood lens.

  In addition, you may replace the light source containing LED and the rotary parabolic mirror in the illuminating device shown in FIGS. 5-9 with the light source containing LED and a convex lens as shown to FIG. 10 (a) and (b). In the light source as shown in FIG. 10, it is also possible to arrange the convex lens corresponding to the hood lens (24) independently while keeping the tip of the hood flat.

  Further, when the center of the light emitting surface of the LED (1) is located at the focal point of the hood lens (24), the light transmitted through the hood lens (24) is substantially parallel light, but the light emitted from the LED (1). Since the surface has an area, a light beam emitted from a position deviating from the focal position of the hood lens (24) does not become a light beam parallel to the optical axis when passing through the hood lens (24). Further, the orientation characteristics of the light source including the LED and the convex lens as shown in FIGS. 10A and 10B are the same as the orientation characteristics of the light source including the LED and the parabolic mirror as shown in FIG. 9C. It has the tendency of.

  In the first to third embodiments of the present invention, the example in which the light beam diffused from the LED is converted into parallel light has been described. However, in order to focus the light diffusing from the LED onto the illumination target surface (imaging region), the rotary parabolic mirror as the first focusing means used in the first to third embodiments of the present invention. It is also possible to use a spheroid mirror having a rotation axis coaxial with the rotation axis. When a spheroid mirror is used as the first focusing means, the light emitting surface of the LED is arranged at one of the focal points of the spheroid mirror (for example, the first focal point F1), and the other focal point of the spheroid mirror is used. What is necessary is just to arrange | position an illumination object surface (imaging area | region) in the position (for example, 2nd focus F2). In this case, the second focusing means can be omitted. That is, the spheroid mirror can have both the function of the first focusing means and the function of the second focusing means used in the first to third embodiments of the present invention.

  FIG. 11 is a diagram for explaining one example of a lighting device according to the fourth embodiment of the present invention. FIG. 11A is a front view of one example of a lighting device according to the fourth embodiment of the present invention, and FIG. 11B is a fourth embodiment of the present invention in the sub-scanning direction (Sy). It is a figure which shows the illumination intensity distribution given by one example of the illuminating device by an example.

  In the example of the illumination device shown in FIG. 11A, a light source including an LED (1) and a spheroid mirror (2b) is used, and the center of the light emitting surface of the LED (1) is a spheroid mirror ( 2b) at the first focal point F1. The illumination target surface (imaging region) (Ai) is disposed at the second focal point F2 of the spheroid mirror (2b). The light emitted from the LED (1) is reflected by the spheroid mirror (2b) and enters the illumination lens (3). The light reflected by the spheroid mirror (2b) is diffused by the illumination lens (3) in the main scanning direction (Sx), while passing through the illumination lens (3) in the sub-scanning direction (Sy). Pass through and focus on the position of the second focal point in the illumination target surface (imaging region) (Ai). As a result, as shown in FIG. 11B, the illuminance distribution (Each_Di) (Total_Di) on the illumination target surface (imaging region) (Ai) in the sub-scanning direction (Sy) is two points in FIG. This is the same as the illuminance distribution indicated by the chain line.

  FIG. 12 is a diagram for explaining another example of the illumination device according to the fourth embodiment of the present invention. FIG. 12 (a) is a front view of another example of a lighting device according to the fourth embodiment of the present invention, and FIG. 12 (b) is a fourth embodiment of the present invention in the sub-scanning direction (Sy). It is a figure which shows the illumination intensity distribution given by another example of the illuminating device by an example.

  In the example of the illumination device shown in FIG. 12A, the light diffused from the LED (1) is changed to the illumination target surface (imaging) by changing the focal position of the convex lens (hood lens) (2c) shown in FIG. Focusing on the area (Ai).

  That is, in the example of the illumination device shown in FIG. 12A, a light source including an LED (1) and a convex lens (2c) is used, and the focal length f of the convex lens (2c) is

It is set like this. Here, a is the distance from the light emitting surface of the LED to the principal point of the convex lens (2c), and b is the distance from the convex lens (2c) to the illumination target surface (imaging region) (Ai). The light emitted from the LED (1) is focused by the convex lens (2c) and enters the illumination lens (3). The light focused by the convex lens (2c) is diffused by the illumination lens (3) in the main scanning direction, while passing through the illumination lens (3) as it is in the sub-scanning direction (Sy), and is illuminated. Focus on (imaging area) (Ai). As a result, as shown in FIG. 12B, the illuminance distributions (Each_Di) (Total_Di) on the illumination target surface (imaging region) (Ai) in the sub-scanning direction (Sy) are two points in FIG. This is the same as the illuminance distribution indicated by the chain line.

  Note that the configuration of the illumination device illustrated in FIGS. 11 and 12 can be applied to the example of the illumination device or the image reading device illustrated in FIGS.

  FIG. 13 is a diagram for explaining one example of an illumination device and an image reading device according to the fourth embodiment of the present invention. FIG. 13A is a diagram showing an example of an illumination device according to the fourth embodiment of the present invention, and FIG. 13B is a diagram of one of the image reading devices according to the fourth embodiment of the present invention. It is a figure which shows an example.

  The example of the illumination device shown in FIG. 13A is the same as the example of the illumination device shown in FIG. In FIG. 13A, in addition to the illumination device, a turning mirror (12) of the image reading device is depicted.

  FIG. 13B shows an example of an image reading device in which an illumination device similar to the example of the illumination device shown in FIG. 11 is mounted on the first traveling body (11). As shown by a two-dot chain line in FIG. 13B, the illumination device is tilted with respect to the reading optical axis (AxR) without bending the illumination optical axis (AxI) of the illumination device shown in FIG. As shown by the solid line in FIG. 13 (b), the illumination optical axis (AxI) of the illumination device shown in FIG. 13 (a) is bent by the folding mirror (6), thereby making the illumination device The contact glass (13) may be disposed in parallel to the surface. In this case, the size of the image reading device in the direction perpendicular to the surface of the contact glass (13) can be reduced.

  FIG. 14 is a diagram for explaining another example of the illumination device and the image reading device according to the fourth embodiment of the present invention. FIG. 14A is a diagram showing another example of the illumination device according to the fourth embodiment of the present invention, and FIG. 14B is another diagram of the image reading device according to the fourth embodiment of the present invention. It is a figure which shows an example.

  The example of the lighting device shown in FIG. 14A is the same as the example of the lighting device shown in FIG. In FIG. 14A, in addition to the illumination device, a turning mirror (12) of the image reading device is depicted.

  FIG. 14B shows an example of an image reading device in which the same illumination device as the example of the illumination device shown in FIG. 12 is mounted on the first traveling body (11). As shown by a two-dot chain line in FIG. 14B, the illuminating device is inclined with respect to the reading optical axis (AxR) without bending the illuminating optical axis (AxI) of the illuminating device shown in FIG. As shown by the solid line in FIG. 14 (b), the illumination optical axis (AxI) of the illumination device shown in FIG. 14 (a) is bent by the folding mirror (6), thereby making the illumination device The contact glass (13) may be disposed in parallel to the surface. In this case, the size of the image reading device in the direction perpendicular to the surface of the contact glass (13) can be reduced.

  In the example of the image reading apparatus shown in FIGS. 13 and 14, as shown in FIG. 7, the light beam is divided before and after the reading optical axis (AxR), and from both before and after the reading optical axis (AxR), The imaging area (Ai) can be illuminated using the divided light flux.

  Here, the light emission color of the LED in the image reading apparatus for monochrome originals and the image reading apparatus for color originals will be described.

  In an image reading apparatus for a monochrome document, an LED that generates light of any of the three primary colors of blue (B), green (G), and red (R) can be used. Alternatively, a white LED can be used. However, since the green color almost represents human visibility, it is preferable to use a green LED.

  In an image reading apparatus for a color document, the illumination apparatus and the image reading apparatus shown in FIGS. 5 to 14 can be used if a color one-dimensional imaging device and a white LED are used.

  When each of R, G, and B primary color LEDs is used, blue (B), green (G), and red (R) LEDs are combined in the illumination device and the image reading device shown in FIGS. Or alternately, and a one-dimensional image sensor for color may be used. For example, in the illumination device and the image reading device shown in FIGS. 5 to 14, blue LEDs are arranged as LEDs L1, L4, L7..., And green LEDs are arranged as LEDs L2, L5, L8. Red LEDs may be arranged as LEDs L3, L6, L9,.

  In this case, the number of LEDs that contribute to the illuminance distribution on the illumination target surface (imaging region) is reduced to one-third compared to the case of a single color (for example, a gain exceeding 6 times in FIG. 5). Therefore, the characteristics of the illuminance distribution due to the light of each color on the illumination target surface (imaging region) are deteriorated. Therefore, if the gain Q is increased by about 3 times by shortening the focal length f of the illumination lens and / or increasing the distance g from the illumination lens to the illumination target surface (imaging region), a monochromatic LED can be obtained. An illuminance distribution as good as the illuminance distribution when used can be obtained.

  FIG. 15 is a diagram for explaining an example of an illumination method and an illumination apparatus according to the fifth embodiment of the present invention. FIG. 15A is a top view of an example of a lighting device according to a fifth embodiment of the present invention, and FIG. 15B is a front view of an example of a lighting device according to the fifth embodiment of the present invention. is there. FIG. 5C shows an illuminance distribution (Each_Di) in the main scanning direction (Sx) on the illumination target surface (imaging region) (Ai) obtained by the example of the illumination method according to the fifth embodiment of the present invention. FIG. 5D is a diagram showing (Total_Di), and FIG. 5D shows the sub-scanning direction (Sy) on the illumination target surface (imaging region) (Ai) obtained by the example of the illumination method according to the fifth embodiment of the present invention. FIG.

The example of the illumination device as shown in FIG. 15 is a light source in which a hood lens of a convex lens (2c) is attached to LED chips (1) of three colors of red (R), green (G), and blue (B). It is an example of the illuminating device for a color including. In the example of the illuminating device shown in FIG. 15, a light source including an LED chip (1) and a convex lens (2c) is used instead of the light source including the LED and the rotating parabolic mirror in the illuminating device illustrated in FIG. Here, as one light source, three types of LED chips (1) for blue (B), green (G), and red (R) (light sources of each color are referred to as light emission sources) are arranged in a row (in FIG. 15, the main light source) . The three types of LED chips (1) arranged in the scanning direction and arranged in a row are covered with a hood lens which is a convex lens (2c). The order of arrangement of the three-color LED chips (1) is not particularly limited. In FIG. 15, the green (G) LED chip (1) is arranged in the center, and the green (G) LED chip (1). Adjacent to is a blue LED chip (1) and a red LED chip (1).

Here, three colors (B, G, R) illuminance distribution in due to a single light source _{L k} containing LED chip (1) and a convex lens (2c) of the illumination target surface (imaging region) (Ai) ( Each_Di) (Total_Di) will be described. The focal length f of the convex lens (2c) is equal to the distance a from the principal point of the convex lens (2c) to the LED chip (1) (f = a).

  In the example of the illumination device as shown in FIG. 15, the optical axis of the green luminous flux generated from the green (G) LED chip (1) coincides with the optical axis of the convex lens (2c). The green light beam generated from the LED chip (1) of G) behaves exactly the same as the light beam generated from the LED in FIG. In the main scanning direction, the width of the cylinder lens constituting the illumination lens (3), that is, the width of the light source,

The surface to be illuminated (imaging region) (Ai) is irradiated with a green light beam having a double width. In the embodiment of the present invention, the value of Q is 2 or more.

  Since the optical axis of the red luminous flux generated from the red (R) LED chip (1) is slightly shifted downward from the optical axis of the convex lens (2c), it is generated from the red (R) LED chip (1). The red luminous flux that passes through the convex lens (2c) is slightly shifted above the green luminous flux generated from the green (G) LED chip (1) and irradiates the illumination target surface (imaging area) (Ai). To do. The ratio Q of the width of the red light beam on the illumination target surface (imaging region) (Ai) to the width of the cylinder lens constituting the illumination lens (3), that is, the width of the light source is the green (G) LED chip (1). ) Is the same as the value for the green luminous flux generated from.

  Since the optical axis of the blue luminous flux generated from the blue (B) LED chip (1) is slightly shifted from the optical axis of the convex lens (2c), it is generated from the blue (B) LED chip (1). The blue light beam passes through the convex lens (2c) and is slightly shifted below the green light beam generated from the green (G) LED chip (1) to illuminate the illumination target surface (imaging region) (Ai). To do. The ratio Q of the width of the blue luminous flux in the illumination target surface (imaging area) (Ai) to the width of the cylinder lens constituting the illumination lens (3), that is, the width of the light source, is the green (G) LED chip (1). ) Is the same as the value for the green luminous flux generated from.

In FIG. 15, a red light beam generated from the light source L _k, indicated by a thick broken line, the green light beam, indicated by the solid line, the blue light beam is indicated by a thin broken line. The concept of the illuminance distribution on the illumination target surface (imaging region) (Ai) by the light beams of the three colors is shown as individual illuminance distribution (Each_Di) in FIG. In addition, light beams generated from other light sources such as L _k−2 , L _k−1 , L _{k + 1} , L _{k + 2} ... Irradiate the illumination target surface (imaging region) (Ai) in the same manner, and thus the light source L _k the illuminance on the illumination target surface on the optical axis (imaging region) (Ai), the illuminance of the light beam generated from the periphery of the light source L _k light sources contribute. FIG. 15C also shows the overall illuminance distribution (Total_Di) resulting from the entire light source.

  As described above, even when the light source including the three-color LED chip (1) and the convex lens (2c) is used, the illumination target surface (imaging region) (Ai) illuminated by the light beams of the respective colors in the main scanning direction. The illuminance unevenness at is explained by applying the illuminance unevenness shown in FIG. 5 for each light flux of each color.

  Next, in the sub-scanning direction (Sy), the blue (B), green (G), and red (R) LED chips (1) exist on the same optical axis, and the focal length f of the convex lens is Since f = a is satisfied, the light beam generated from the LED (1) of each color passes through the convex lens (2c) and becomes substantially parallel light.

  Here, when the illumination device shown in FIG. 15 does not include the focusing lens (4a), the parallel luminous flux of each color that has passed through the illumination lens (3) irradiates the illumination target surface (imaging region) (Ai) as it is. To do. As a result, the illuminance distribution (Di) on the illumination target surface (imaging region) (Ai) in the sub-scanning direction (Sy) is a broad distribution as shown by the solid line in FIG. On the other hand, the illumination device shown in FIG. 15 is provided between the illumination lens (3) and the illumination target surface (imaging region) (Ai) and is separated from the illumination target surface (imaging region) (Ai) by the focal length F. When the focusing lens (4a) disposed at the position is included, the parallel light beams of the respective colors that have passed through the illumination lens (3) are focused on the illumination target surface (imaging region) (Ai). As a result, the illuminance distribution on the illumination target surface (imaging region) (Ai) in the sub-scanning direction (Sy) is a sharp distribution (Each_Di) (Total_Di) as shown by a two-dot chain line in FIG. Become.

  As a means for focusing the light generated from the LED chip (1) on the illumination target surface (imaging region) (Ai) in the sub-scanning direction (Sy), the focal length f of the convex lens (2c) is shown in FIG. Like the example of the lighting device in

The method to do is mentioned. Here, a is the distance from the light emitting surface of the LED chip (1) to the principal point of the convex lens (2c), and b is from the principal point of the convex lens (2c) to the illumination target surface (imaging region) (Ai). Is the distance. In this case, it is not necessary to provide the focusing lens (4a).

  When the illumination device as shown in FIG. 15 is mounted on the first traveling body of the image reading device, the illumination device as shown in FIG. 15 is applied to the image reading device as shown in FIGS. be able to.

  FIG. 16 is a diagram for explaining an example of an illumination method and an image reading apparatus according to the sixth embodiment of the present invention. FIG. 16A is a top view of an example of the image reading apparatus according to the sixth embodiment of the present invention, and FIG. 16B is a front view of the example of the image reading apparatus according to the sixth embodiment of the present invention. FIG. FIG. 16C is a diagram showing the illuminance distribution in the sub-scanning direction on the illumination target surface (imaging region) obtained by the example of the illumination method according to the sixth embodiment of the present invention.

  An example of the image reading apparatus as shown in FIG. 16 is a light source in which a hood lens of a convex lens (2c) is attached to LED chips (1) of three colors of red (R), green (G), and blue (B). FIG.

  In the example of the image reading apparatus as shown in FIG. 16, the arrangement of the three-color LED chips (1) of the illumination system corresponds to the arrangement of the one-dimensional imaging element (15) of the reading system for reading the image of each color. Attached. In the image reading apparatus as shown in FIG. 16, the system on the left side of the illumination target surface (imaging region) (Ai) is the illumination system, and the system on the right side of the illumination target surface (imaging region) (Ai) is the reading system. It is. Then, the imaging area (Ai) is illuminated using the illumination system, and the image of the original placed in the imaging area (Ai) is read by the reading system.

  In the reading system of the color image reading apparatus, a three-line CCD in which three one-line CCDs (one-dimensional imaging element (15)) are arranged in parallel is used. Each of the three one-line CCDs is provided with a color filter (18) that transmits red (R), green (G), or blue (B), and each of the three one-line CCDs has a color filter. An image of a color that passes through (18) is read. A three-line CCD provided with such a color filter (18) cannot simultaneously read images at the same location in the imaging area (Ai) of the document. In the current image reading apparatus, the size of a pixel constituting a 600 dpi image is 42.3 μm. However, the reading system of the current image reading apparatus is a reduction optical system, and the image sensor has a reading system. It corresponds to 10 μm, 7 μm, or 4.7 μm depending on the reduction ratio. However, it is difficult to arrange 1-line CCDs at such short intervals. Actually, when three one-line CCDs are arranged in the sub-scanning direction (Sy), it is necessary to separate the three one-line CCDs from each other by a distance corresponding to three to four pixels. Here, the interval between the three one-line CCDs corresponds to approximately 0.4 to 0.2 mm in the imaging area (Ai) of the document surface. That is, red, green, and blue images are read at intervals of 0.4 to 0.2 mm in the imaging area (Ai) on the document surface. Therefore, the red, green, and blue light fluxes generated from the red, green, and blue LED chips (1) are irradiated at intervals of 0.4 to 0.2 mm in the imaging area (Ai) of the document surface. Is preferred.

  Here, in the sub-scanning direction (Sy), the relationship between the arrangement of the three-color LED chips (1) of the illumination system and the center position of the luminous flux of each color on the illumination target surface (imaging region) (Ai) is shown in FIG. Shown in b). In FIG. 16B, a is the distance from the light emitting surface of the LED chip to the principal point of the convex lens (2c), and b is from the principal point of the convex lens (2c) to the principal point of the focusing lens (4a). C is the distance from the principal point of the focusing lens (4a) to the illumination target surface (imaging region) (Ai). M0 is the distance between the LED chips (1) of each color, m1 is the distance between the centers of the light beams of each color from the LED chips (1) of each color passing through the focusing lens (4a), and m2 is The distance between the centers of the luminous fluxes of the respective colors from the LED chips (1) of the respective colors on the illumination target surface (imaging region) (Ai). Furthermore, when the focal length of the convex lens (2c) is f0 and the focal length of the focusing lens (4a) is f1, f0 = a and f1 = c.

The relationship holds. Therefore, from the equations (1) and (2),

The relationship holds.

  From equation (2), m2 = m1 when b = c, m2> m1 when b <c, and m2 <m1 when b> c.

  From equation (3), when b = c,

And when b <c,

And when b> c,

It is.

  In FIG. 16B, f0 = a and f1 = c, and b = c. The illuminance distribution in the sub-scanning direction (Sy) in the image reading apparatus shown in FIGS. 16A and 16B is shown in FIG. 16C. In practice, while considering the arrangement of the components of the illumination system, By maintaining the above relationship, the peak of the illuminance distribution (Di) on the illumination target surface (imaging region) (Ai) illuminated by the light beams of each color corresponds to the position of the one-line CCD that reads the image of each color. In this way, the illumination system can be designed.

  In addition, it is assumed that the arrangement of R, G, and B colors is on a straight line in the main scanning direction (Sx) or the sub-scanning direction (Sy), but the arrangement of R, G, and B colors is particularly limited. For example, the colors of R, G, and B may be arranged at the vertices of a triangle, the letter “K” in hiragana, and the letter “L” in English. In such a case, it is possible to optimally design the illumination device and the image reading device by combining the ideas shown in FIGS. 15 and 16.

  FIG. 17 is a view for explaining one example of the illumination method and illumination apparatus according to the seventh embodiment of the present invention. FIG. 17A is a perspective view of one example of an illumination device according to the seventh embodiment of the present invention, and FIG. 17B is one of the image reading devices according to the seventh embodiment of the present invention. FIG. 17C is a side view of one example of the image reading apparatus according to the seventh embodiment of the present invention. FIG. 17D is a diagram showing the illuminance distribution in the main scanning direction on the illumination target surface (imaging region) obtained by one of the illumination methods according to the seventh embodiment of the present invention.

  In the example of the illumination device as shown in FIG. 17, a plurality of LEDs (1) having a rectangular light emitting surface are used. Moreover, the example of the illuminating device as shown in FIG. 17 has a rectangular light emitting surface in the main scanning direction (Sx) between the plurality of LEDs (1) having a rectangular light emitting surface and the illumination target area (Ai). The illumination lens (3) of the cylinder lens array which diffuses the light beam which generate | occur | produces from several LED (1) provided with is included. A light flux generated from the plurality of LEDs (1) having a rectangular light emitting surface in the sub-scanning direction (Sy) between the plurality of LEDs (1) having a rectangular light emitting surface and the illumination lens (3). A focusing lens (4a) of a cylinder lens for focusing the lens is inserted. The concept of setting the focal length of the cylinder lens constituting the cylinder lens array of the illumination lens (3) and the cylinder lens of the focusing lens (4a) is the same as that of the first to sixth embodiments. The focusing lens (4a) is shown to be focused as shown in FIG. 17 (c), but in the sub-scanning direction (Sy), a plurality of LEDs (1) having a rectangular light emitting surface are used. The generated light beam does not necessarily have to be focused, and may be converted into parallel light or diffused light. Furthermore, the insertion of the focusing lens (4a) is not always essential.

  Further, in the example of the illumination device as shown in FIG. 17, as shown in FIG. 17B, the light is generated from each of the plurality of LEDs (1) having a rectangular light emitting surface in the main scanning direction (Sx). The luminous flux is not only incident on the cylinder lens of the illumination lens (3) corresponding to each LED (1), but also in the vicinity of (or its) the cylinder lens of the illumination lens (3) corresponding to each LED (1). It also enters the cylinder lens (adjacent to the cylinder lens). As a result, the luminous flux generated from each of the plurality of LEDs (1) having a rectangular light emitting surface is further diffused by the illumination lens (3). For example, as shown in FIG. 17B, the light beam diffused from one L4 of the LED (1) mainly enters the cylinder lens corresponding to the L4 of the LED (1), and has a preset magnification. The illumination target surface (imaging area) (Ai) is irradiated. However, a part of the light beam diffused from one LED 4 of L (1) also enters the cylinder lens corresponding to L3 and L5 of LED (1) adjacent to L4 of LED (1). Further, a part of the light beam diffused from one LED 4 of L (1) also enters the cylinder lens corresponding to L2 and L6 of LED (1) located in the vicinity of L4 of LED (1). As a result, in the example of the illumination device as shown in FIG. 17, the light generated from the LED (1) can be diffused more widely.

  Then, by using an illuminating device as shown in FIGS. 17A, 17B, and 17C, as shown in FIG. 17D, a plurality of LEDs (1) are arranged in the main scanning direction (Sx). ) Variation in illuminance distribution on the illumination target surface (imaging region) (Ai) due to the variation in the luminous efficiency. That is, in the conventional illumination device as shown in FIG. 4, the illuminance on the illumination target surface (imaging region) (Ai) illuminated by the LED (1) having lower light emission efficiency in the main scanning direction (Sx). Even if the ratio of the illuminance h1 on the illumination target surface (imaging region) (Ai) illuminated by the LED (1) having higher luminous efficiency with respect to h2 is approximately double, FIG. When using an illuminating device including an illumination lens (3) as shown in (b) and (c), an illumination target surface (imaging region) (illuminated by an LED (1) having a lower luminous efficiency ( The ratio (h1 ′ / h2 ′) of the illuminance h1 ′ at the illumination target surface (imaging region) (Ai) illuminated by the LED (1) having higher luminous efficiency with respect to the illuminance h2 ′ at Ai) ( significantly less than h1 / h2) It is possible. More specifically, as shown in (Actual_Di2) in FIG. 17D, the fluctuation range of the value of (h1 '/ h2') is easily suppressed to about 10%.

In the illuminating device as shown in FIG. 17, since the diffusion range of the light beam in the main scanning direction (Sx) is wider, the side mirrors (5a, 5b) shown in FIG. It is effective to provide. It is effective to provide the side mirrors (5a, 5b) up to the side surface of the LED (1). In this case, the diffused light from the LED can be applied to the illumination target surface (imaging region) (Ai) without diffusing outside the illumination target region (Ai) in the main scanning direction (Sx). .

  FIG. 18 is a diagram for explaining another example of the illumination device according to the seventh embodiment of the present invention. FIG. 18A is a top view of another example of an illuminating device according to the seventh embodiment of the present invention, and FIG. 18B is another diagram of the image reading device according to the seventh embodiment of the present invention. It is a front view of an example.

  In the example of the illumination device as shown in FIG. 18, a parabolic mirror (2d) is used instead of the condenser lens (4a) in the example of the illumination device as shown in FIG. LED with a rectangular light emitting surface is used side by side in the same manner as in FIG. Here, the parabolic mirror (2d) has a parallel plane cross section in the main scanning direction (Sx) and a parabolic cross section in the sub scanning direction (Sy).

  Further, in the example of the illumination device as shown in FIG. 18, there is no barrier against the light flux generated from each of the plurality of LEDs (1) in the main scanning direction (Sx). Similarly to the example, the luminous flux generated from each LED (1) not only enters the cylinder lens of the illumination lens (3) corresponding to each LED (1), but also the illumination corresponding to each LED (1). It also enters the cylinder lens in the vicinity of (or adjacent to) the cylinder lens of the lens (3). As a result, the luminous flux generated from each LED (1) is more diffused by the illumination lens (3). For example, a light beam diffusing from one L4 of the LED (1) mainly enters a cylinder lens corresponding to L4 of the LED (1), and is illuminated with a preset magnification (imaging area) (Ai). Irradiate. However, a part of the light beam diffused from one LED 4 of L (1) also enters the cylinder lens corresponding to L3 and L5 of LED (1) adjacent to L4 of LED (1). Further, a part of the light beam diffused from one LED 4 of L (1) also enters the cylinder lens corresponding to L2 and L6 of LED (1) located in the vicinity of L4 of LED (1). As a result, in the example of the illumination device as shown in FIG. 18, the light generated from the LED (1) can be diffused more widely.

  In the illuminating device as shown in FIG. 18, since the diffusion range of the light beam in the main scanning direction (Sx) is wider, it is effective to provide the side mirrors (5a, 5b) in the illuminating device. It is effective to provide the side mirrors (5a, 5b) up to the side surface of the parabolic mirror (2d). In this case, the diffused light from the LED can be applied to the illumination target surface (imaging region) (Ai) without diffusing outside the illumination target region (Ai) in the main scanning direction (Sx). .

  Although the illuminating device shown in FIG. 18 includes a focusing lens (4a), the focusing lens (4a) is not necessarily an essential component. In the example of the illumination device as shown in FIG. 18, the parabolic mirror (2a) is used as the first focusing means, but an ellipsoidal mirror can also be used as the first focusing means. Here, the ellipsoidal mirror has a parallel plane section in the main scanning direction (Sx), and an ellipsoidal section in the sub-scanning direction (Sy). The first focal point of the elliptical surface of the elliptical mirror is located at the center of the light emitting surface of the LED, and the second focal point of the elliptical surface of the elliptical mirror is located in the illumination target area (Ai). When such an ellipsoidal mirror is used as the first focusing means, the focusing lens (4a) is not necessary.

  Further, an illumination device for a color image reading apparatus using independent LEDs of three colors of R, G, and B will be described. For example, as shown in FIGS. 17B and 17C, the LEDs of L1 to L7 as shown in FIG. 17 are configured by one color LED and other two color LEDs are added. Specifically, as shown in FIG. 17C, three other colors (R and B) LEDs are arranged on both sides in the sub-scanning direction (Sy) of the one color (G) LED, so that three A light source composed of colored LEDs can be provided. The example of the illumination device as shown in FIG. 17C functions in the same manner as the example of the illumination device as shown in FIG. (However, the condenser lens (4a) is arranged at the position of the condenser lens (2c) in FIG. 16 (b), and c = 0 among the relations of a, b, and c).

  FIG. 19 is a diagram for explaining an example of a lighting apparatus according to the eighth embodiment of the present invention. FIG. 19A is a top view of another example of an illuminating device according to the eighth embodiment of the present invention, and FIG. 19B is another diagram of the image reading device according to the eighth embodiment of the present invention. It is a front view of an example.

  In the first to seventh embodiments of the present invention, a cylinder lens array composed of a plurality of adjacent convex cylinder lenses has been shown as the illumination lens. A cylinder lens array composed of a plurality of concave cylinder lenses can also be used.

  In the example of the illumination device as shown in FIG. 19, a cylinder lens array including a plurality of concave cylinder lenses arranged adjacent to each other is used as the illumination lens (3). Even when a cylinder lens array composed of a plurality of concave cylinder lenses arranged adjacent to each other is used as the illumination lens (3), the luminous flux generated from the LED (1) is changed in the main scanning direction (Sx). Can be diffused. Here, the focal length of each concave cylinder lens constituting the cylinder lens array is f, and the illumination target surface (imaging area) (Ai) from the principal point of the concave cylinder lens corresponding to one of the LEDs (1). ) Is g, the magnification factor Q of the width of the luminous flux of light emitted from one of the LEDs (1) in the main scanning direction (Sx) is

In the embodiment of the present invention, Q is 2 or more.

  In the first to eighth embodiments of the present invention, the original carriage (contact glass) in the image reading apparatus, the reading system including the imaging lens and the one-dimensional imaging device are fixed, while the first traveling body and The second traveling body moves differentially in the sub-scanning direction. And the illuminating device by the 1st-8th Example of this invention is mounted in a 1st traveling body. Since only the turning mirror that bends the optical path of the light reflected from the imaging region is mounted on the first traveling body, except for the lighting device, the mass of the first traveling body does not increase, and the first traveling body does not increase. The image reading by the movement of the second traveling body is suitable for high-speed reading. However, when low-speed reading is permitted, it is conceivable that the reading device is also mounted on the first traveling body. In this case, since the second traveling body is unnecessary, only one traveling body may be provided. ).

  FIG. 20 is a diagram for explaining an example of an image reading apparatus according to the ninth embodiment of the present invention. FIG. 20A is a diagram for explaining an example of an image reading apparatus according to the ninth embodiment of the present invention, and FIG. 20B is an illustration of the image reading apparatus according to the ninth embodiment of the present invention. It is a figure explaining another example.

  In the image reading apparatus as shown in FIGS. 20A and 20B, the illumination unit (10) as the illumination apparatus according to the first to eighth embodiments of the present invention is replaced with a reading unit (16) as a reading system. ) And the traveling body (11a). Since the reading unit (16) is a reduction optical system including an imaging lens and an imaging device, a certain distance from the document surface to the imaging lens is required.

  In the image reading apparatus as shown in FIG. 20A, the image light reflected from the document surface is once redirected by the deflecting mirror (12) in a direction parallel to the contact glass (13). Then, after being folded twice by the two folding mirrors (17a) and (17b), they are guided to the reading unit (16).

In the image reading apparatus as shown in FIG. 20 (b), the image light reflected from the document surface is folded back diagonally to the upper right by the turning mirror (12), and is reflected by the first folding mirror (17a). After being changed in a direction parallel to the contact glass (13), it is directed to the second folding mirror (17b). The light incident on the second folding mirror (17b) is reflected again slightly downward and returned to the first folding mirror (17a) again. The light returned to the first folding mirror (17a) is reflected diagonally downward, further reflected by the third folding mirror (17c), and in a direction parallel to the surface of the contact glass (13),
Guided to the reading unit (11).

  As shown in FIGS. 20A and 20B, both the reading system such as the reading unit (11) and the illumination system such as the illumination unit (10) are mounted on the traveling body (11a). However, any of the illumination devices according to the first to eighth embodiments of the invention can be used as the illumination unit (10). In Fig.20 (a), the illuminating device shown in FIG.7 (e) is employ | adopted directly. In the image reading apparatus as shown in FIG. 20B, a convex lens is used instead of the rotary paraboloid mirror as the first focusing means in the image reading apparatus shown in FIG.

  In the first to ninth embodiments of the present invention, the illuminating device and the illuminating method for mounting on a reduction optical system or a digital image reading device for reading an image with an image sensor have been described. However, the illumination apparatus and illumination method as shown in the first to ninth embodiments of the present invention can also be used as an illumination method for mounting in a 1 × optical system or an analog copying machine.

  FIG. 21 is a diagram illustrating an example of an image reading apparatus according to the tenth embodiment of the present invention. An example of the image reading apparatus as shown in FIG. 21 is an image reading apparatus for an image forming apparatus that copies a sheet-like document. The imaging lens (14) is a microlens array, and a large number of macrolenses are arranged so that the length of the microlens array is the same as the width of a sheet original (33) such as paper. Is. The imaging lens (14) is arranged just in the middle of the imaging area (Ai) and the photoreceptor (31) in order to provide an equal magnification optical system. The sheet document (33) is pressed and fed by the paper feed roller (32) in the imaging region (Ai) portion on the contact glass (13) with little friction with the sheet document (33). The photosensitive member (31) is moved in synchronism with the feeding of the sheet original (at the same speed). Note that illustration of peripheral devices of the photosensitive member such as a charging device and a transfer device for charging the photosensitive member (31) is omitted.

  In the example of the image reading apparatus as shown in FIG. 21, the illuminating apparatus is obtained by removing the traveling body and changing the position of the folding mirror in the illuminating apparatus shown in FIG. Using such an illuminating device, the imaging region (Ai) of the sheet original (33) is illuminated one-dimensionally, and an image on the sheet original (33) is transferred to the photosensitive member (14) via the imaging lens (14). 31) Projecting above. Then, by sequentially moving the sheet original (33) and the photosensitive member (31), the entire image on the sheet original (33) can be projected as a two-dimensional image on the photosensitive member (31). Thereafter, as an analog copying machine process, an image is transferred onto plain paper, which is the same as a commonly used paper, to obtain a hard copy of the image, but detailed description of a known analog copying process is omitted.

  As described above, even in an analog copying machine, unevenness in illuminance can be reduced by using the illumination method and the illumination device according to the embodiment of the present invention, so that a high-quality image can be obtained.

The above description has described a method of uniformly illuminating the illumination target surface (imaging region). For application to an image reading apparatus using an equal magnification optical system or an image forming apparatus, the application as it is is good. In an image reading apparatus using a reduction optical system, the amount of light in the central portion of the illumination target area in the main scanning direction is reduced more than the peripheral portion due to the cosine fourth power characteristic (cos ⁴ θ characteristic) of the imaging lens. It becomes convenient. In that case, it can be easily realized by increasing the distance between the LEDs as the light source from the peripheral part toward the central part in accordance with the cosine fourth power characteristic. Of course, in that case, it is desirable to diffuse the luminous flux emitted from the LED even in the roughest place to more than twice the LED interval.

  FIG. 22 is a diagram for explaining the relationship between the illuminance distribution (Di) in the imaging region (Ai) and the relative lightness of the reduction optical system on the CCD in the image reading apparatus using the reduction optical system. FIG. 22A is a diagram showing the arrangement of the imaging region (Ai), the imaging lens, and the one-dimensional CCD in the image reading apparatus using the reduction optical system, and FIG. It is a figure explaining the relationship between the brightness distribution of the image imaged on one-dimensional CCD by an image lens, and the illuminance distribution (Di) requested | required of (2) imaging region (Ai).

  As shown in FIG. 22A, an image reading apparatus that places a one-dimensional CCD in parallel with an imaging region (Ai) and places an imaging lens (14) therebetween to form an image on the one-dimensional CCD. When the image in the imaging region (Ai) is imaged on the one-dimensional CCD as the one-dimensional imaging device (15) by the imaging lens (14), the image is formed by the imaging lens (14). The brightness of the image at the peripheral portion on the one-dimensional CCD is lower than the brightness of the image at the central portion on the one-dimensional CCD.

In FIG. 22A, W is the length of the imaging region (Ai) in the main scanning direction (Sx), and the imaging lens (14) has its optical axis in the vertical direction at the center of the imaging region (Ai). If the distance from the imaging region (Ai) to the imaging lens (14) is Ld, the angle of the light ray incident on the imaging lens (14) with respect to the optical axis of the imaging lens (14) The maximum value θ _max of θ is
θ _max = tan ⁻¹ [W / (2 × Ld)]
It becomes.

At this time, the relative value of the brightness of the image formed by the imaging lens (14) at each position in the main scanning direction (Sx) on the one-dimensional CCD corresponds to the position according to the so-called cosine fourth law. With respect to the angle θ of the light ray incident on the imaging lens from the position in the image pickup area (Ai), it changes by cos ⁴ θ as shown by the curve (1) in FIG. As a result, the imaging lens (14) around the main scanning direction (Sx) with respect to the brightness of the image on the one-dimensional CCD imaged by the imaging lens (14) at the center in the main scanning direction (Sx). The brightness of the image on the one-dimensional CCD imaged by is reduced by several tens of percent.

  On the other hand, the amount of light incident on the one-dimensional CCD is converted into an electric signal by the one-dimensional CCD. Therefore, after converting the amount of light into an electric signal, the amplification factor of the electric signal is changed to change the imaging lens (14 It is possible to correct the difference in brightness of the image formed by (). However, in this case, since the dynamic range becomes small, noise increases around the one-dimensional CCD in which the brightness of the image formed by the imaging lens (14) is relatively low. As a result, the image read by the one-dimensional CCD becomes dirty.

  Therefore, an imaging region in the vicinity of the optical axis of the imaging lens (14) is located on the imaging region (Ai) side of the imaging lens (14) so as to be inversely proportional to the relationship shown by the curve (1) in FIG. Insert a light shielding mask that increases the light shielding amount for the light from the position (Ai), or the reflectance of the reflecting plate that reflects the light from the light source becomes lower at the center of the reflecting plate. It is conceivable to make the illuminance of the light imaged on the one-dimensional CCD constant by changing in this way. In such a case, the correction of the electric signal can be reduced. However, shielding or discarding the light emitted from the light source is not desirable from the viewpoint of energy saving.

  That is, the imaging region (Ai) is illuminated so that the illuminance distribution (Di) required for the imaging region (Ai) shown in the curve (2) in FIG. It is desirable to do. If it does so, the utilization efficiency of the light discharge | released from a light source can be improved, As a result, the energy of the light which illuminates the imaging region (Ai) can be reduced (energy saving is achieved).

As a method for making the brightness distribution of the image on the one-dimensional image pickup device (CCD) (15) imaged by the imaging lens (14) constant, for example, the interval between a plurality of light sources such as LEDs is changed. A method of changing the distance from the imaging region (Ai) to the plurality of light sources, a method of changing the divergence angle of the luminous flux of light emitted from the plurality of light sources, and a plurality of A method for changing the direction of the optical axis of the light source is available. By adopting such a method, the illuminance distribution (Di) of the light illuminating the imaging region (Ai) in the main scanning direction (Sx) is 1 / as shown by the curve (2) in FIG. so as to have the characteristics of cos ⁴ theta, it may be associated with different arrangement of a plurality of light sources.

In the eleventh embodiment of the present invention, the illuminance distribution (Di) of the light that illuminates the imaging target area (imaging area) (Ai) is made to match the characteristic of 1 / cos ⁴ θ by changing the arrangement interval of the plurality of light sources. An example is shown.

  FIG. 23 is a diagram for explaining a method of determining the arrangement intervals of a plurality of light sources that illuminate the imaging target area (Ai) so that the relative brightness of an image formed on the one-dimensional CCD is constant.

  In order to make the relative brightness of the image formed on the one-dimensional CCD constant, the arrangement interval of a plurality of light sources (for example, LEDs) that illuminate the imaging target area (Ai) is set at the center (imaging lens). Narrows away from the optical axis). In FIG. 23, the arrangement shown in FIG. 22A is shown rotated by 90 degrees counterclockwise. In the symbols shown there, the same symbols as those in FIG. 22 have the same meaning. In FIG. 23, Wh is half the length W of the imaging target area (Ai) in the main scanning direction (Sx), and is calculated from the center of the imaging target area (Ai).

  In order to calculate the interval between the plurality of light sources that illuminate the imaging target area (Ai) so that the relative brightness of the image formed on the one-dimensional CCD is constant, the sub-scanning direction (Sy) The design or simulation is performed on the assumption that the luminous flux does not diverge. Specifically, in the sub-scanning direction (Sy), the imaging target area (Ai) is illuminated with the light emitted from the plurality of light sources as parallel light, or the light emitted from the plurality of light sources is input to the imaging target area ( Focus to Ai) or adopt either in between.

  As shown in FIG. 23, since the upper half area and the lower half area are symmetrical with respect to the center line (optical axis of the imaging lens) in FIG. 23, only the lower half area is shown for convenience of explanation. It explains using. First, the lower half area (half of the imaging target area (Ai) in the main scanning direction (Sx)) is divided into N, and the point on the center line is set as the origin. Further, the point number of the origin is set to 0, and the point numbers of the respective division points are numbered 1 to n in the order close to the origin, the interval from the origin 0 to the division point 1, the division point 1 to the division point 2 ,..., And the intervals from the dividing point n-1 to the end point n are represented by w1, w2,.

Here, an interval of w1 to wn is obtained so that the illuminance distribution (Di) required for the imaging target area (Ai) shown in the curve (2) of FIG. 22B is obtained. The N division of the imaging target area (Ai) in the scanning direction (Sx) is initially divided into N equal parts. Assuming that the entire area to be imaged (Ai) is illuminated with a constant illuminance, the relative brightness of the position corresponding to each division point imaged on the one-dimensional CCD by the imaging lens is determined by the cosine fourth law. Ask. Specifically, the relative brightness of the image formed on the one-dimensional CCD by the imaging lens corresponding to the kth division point on the imaging target area (Ai) is cos ⁴ θ _k . The sum of these relative brightness values is

It is. Here, θ _k is an angle of a straight line connecting the center of the imaging lens and the kth division point of the imaging target area (Ai) with respect to the optical axis of the imaging lens. Note that θ _n is an angle of a straight line connecting the center of the imaging lens and the nth division point with respect to the optical axis of the imaging lens, and coincides with θmax.

  Next, the distance between the division points is given again by division in proportion to the relative brightness corresponding to each division point. That is, the intervals w1, w2,.

According to the calculation.

  Since the intervals w1, w2,..., Wn between the division points obtained here are slightly deviated from the target intervals, the same calculation is performed again.

First, the position of each dividing point is re-divided at intervals w1, w2,..., Wn obtained by the above equation, and a straight line connecting the center of the imaging lens and the k-th dividing point with respect to the optical axis of the imaging lens. The angle θ ′ _k is calculated. Next, the relative brightness of the image formed on the one-dimensional CCD corresponding to each division point at each of the obtained intervals w1, w2,. Specifically, the relative brightness of the image formed on the one-dimensional CCD corresponding to the kth division point is cos ⁴ θ ′ _k . The sum of the relative brightness is

It is.

  Here, based on this, the intervals w′1, w′2,.

According to the calculation.

  By repeating such an operation infinitely, the target interval between the division points is approached as much as possible. However, as will be described later, in the result obtained by simulating N as 12, the interval obtained by the first calculation is obtained. The difference between the corresponding intervals of w1, w2, ..., wn and the intervals w'1, w'2, ..., w'n obtained by the second calculation is less than ± 0.4% at maximum. It was. Since such a difference is practically much smaller than the fluctuation of other factors (such as part accuracy and machining accuracy), the intervals w1, w2,..., Wn obtained by the first calculation are used. There is no problem.

The light source is arranged on the distance L0 corresponding to the division point of the imaging target area (Ai) thus obtained, and an illuminance distribution of 1 / cos ⁴ θ is given to the periphery of the imaging target area (Ai). Then, it is necessary to arrange the light source beyond the imaging target area (Ai) width W. That is, in addition to the N light sources at positions 0 to n, n + 1, n + 2, n + 3,... On an extended line that is out of the imaging target area (Ai) on the line separated from the imaging target area (Ai) by L0. It is necessary to arrange the light source (this arrangement position can be easily obtained by deducting the calculation method described above, but a detailed description is omitted).

  Next, a method for obtaining the illuminance distribution of the imaging target area (Ai) illuminated by a plurality of light sources whose intervals are adjusted will be described.

FIG. 24 is a diagram illustrating a specific arrangement of a plurality of light sources that illuminate the imaging target area (Ai) so that the relative brightness of an image formed on the one-dimensional CCD is constant. FIG. 24A is a diagram showing the arrangement of a plurality of light sources and the position of the mirror surface on which the side mirror is arranged, and FIG. 24B is a diagram showing an example of the radiation characteristics of the light sources.
FIG. 24A is an enlarged view of a portion expressed on the left side of the imaging target surface (imaging target area) (Ai) in FIG.

  As shown in FIG. 24 (a), N division is performed at intervals obtained in the above description, separated from the illumination target area (imaging target area) (Ai) by L0 and parallel to the imaging target area (Ai). Thus, a light source is placed at each obtained division point. Further, a mirror surface (side mirror) is placed at the position of the outside PM1, and the relative illuminance at each position of the imaging target area (Ai) is calculated. This mirror surface reflects light beams emitted from a plurality of light sources placed on the light source arrangement position corresponding to the points obtained by dividing the range of the imaging target area (Ai), as if the light source is on the extended line. Is irradiated with the range of the illumination target area (Ai).

In FIG. 24A, the positions of n + 1 light sources obtained by dividing the half of the imaging target area (Ai) in the main scanning direction (Sx) into N are denoted by P ₀ , P _{1 ,.} In addition, the position of the image of the light source (virtual light source VLS) arranged at P ₀ , P ₁ ,... P _n obtained by the side mirror provided at the position of the outside PM1 of the _nth light source is P _{n + 1} , P _{n + 2.} ,... P _{2n + 1} . Here, located on the light source and P _{n + 1,} placed in a position of P _n, the distance between the image of the light source obtained by the side mirrors, obtained by deducing the calculation method described above. Since the position P _n and the position P _{n + 1} are in a mirror image relationship with the side mirror, the mirror surface of the side mirror is provided at a position that is half the distance between the position P _n and the position P _{n + 1} . Furthermore, the distance between the position _{P n + 1} and deduced the calculation method described above and the position _{P n + 2,} ..., when determining the distance between the position _{P 2n} and the position _{P 2n + 1,} the position _{P n + 1,} the position _{P n + 2} The distance between the positions P _{n + 2} and P _{n + 3} needs to be narrowed as it progresses. However, in the arrangement shown in FIG. (Of course, the interval between the position P _{n + 1} and the position P _{n + 2} ,..., The interval between the position P _2n and the position P _{2n + 1} , respectively, is the interval between the position _Pn−1 and the position P _{n ,.} , Corresponding to the interval between position P ₀ and position P ₁ ). Note that a side mirror paired with a side mirror provided outside the nth light source is also provided in the upper half area with respect to the center line of the imaging target area (Ai) (the optical axis of the imaging lens) ( PM2) and a side mirror provided outside the nth light source are arranged in parallel to each other. For this reason, an infinite number of imaginary light sources, which are mirror images, are generated by the pair of side mirrors. Among these, the imaginary light source generated by two or more reflections by the side mirrors is located far away from the imaging target area (Ai). Therefore, the contribution ratio to the illuminance distribution (Di) in the imaging target region (Ai) is extremely small and can be ignored.

Next, the relative illuminance I (Mm) at an arbitrary point Mm in the imaging target area (Ai) illuminated by a plurality of light sources is determined. If the angle between the vertical line with respect to the imaging target area (Ai) and the radiation vector of light emitted from the light source toward the point Mm is α, the distance from the light source to the imaging target area (Ai) is L0. The distance from a certain light source to the point Mm is L0 / cos α. Assuming that the light beam emitted from the light source does not diverge in the sub-scanning direction (Sy), the light at the point Mm in the imaging target area (Ai) illuminated by the light emitted from each light source. The intensity is inversely proportional to the distance L0 / cosα from each light source to the point Mm. Further, the degree of reduction of the luminous flux due to the inclination of the surface at the same point Mm is cos α.
On the other hand, as shown in FIG. 24B, the intensity of the light emitted from the light source in the direction of the radiation vector that forms an angle α with the vertical line with respect to the imaging target area (Ai) is the radiation vector of the light emitted from the light source. Depends on the distribution (envelope). Although the radiation vector distribution (envelope) of a light source such as an actual LED has a complicated shape, it is approximated by a circle or an ellipse for convenience of calculation. For example, as shown in (1) of FIG. 24B, when the envelope of the radiation vector of light emitted from the light source can be approximated to a circle, the radiation vector having an angle α with respect to the central axis of the light source. The intensity of light emitted from the light source in the direction decreases by cos α. When the envelope of the radiation vector of the light emitted from the light source can be approximated to an ellipse, cos ² α as shown in (2) of FIG. It is possible to approximate such as cos ⁴ α as shown in (3) of FIG.

  Therefore, the relative illuminance I (Mm) at an arbitrary point Mm in the imaging target area (Ai) illuminated by a plurality of light sources is

Represented by Here, A _k is a relative value of the total amount of light emitted from the k-th light source, and α _k is the angle of the radiation vector of the k-th light source toward the point Mm with respect to the direction of the optical axis of the imaging lens. is there. Further, a is a coefficient that approximates the envelope of the radiation vector of the light source. For example, when the envelope of the radiation vector of the light source is close to a circle, as shown in (1) of FIG. 24B, a = 1, and when the envelope of the radiation vector of the light source is close to an ellipse In FIG. 24B, (a) and (a) are set to a> 1, as in a = 2 and a = 3 shown in (2) and (3). If the envelope of the radiation vector of the light source is flat, it can be approximated to a <1.

In this way, it is possible to calculate the illuminance distribution over the entire area of the imaging target area (Ai) illuminated by the entire light source arranged in the lower half from the center line (CL) of the imaging target area (Ai). Further, if the obtained illuminance distribution is reversed symmetrically with respect to the center line (CL), the imaging target illuminated by the entire light source arranged in the upper half from the center line (CL) of the imaging target area (Ai) An illuminance distribution over the entire area (Ai) can be obtained. The illuminance distribution over the entire area of the imaging target area (Ai) illuminated by the entire light source arranged in the lower half from the center line (CL) of the imaging target area (Ai) and the center line (CL of the imaging target area (Ai) ) To obtain the illuminance distribution over the entire area of the imaging target area (Ai) illuminated by all light sources. be able to. However, when performing this calculation, the luminous flux emitted from the light source placed on P ₀ is used both when calculating the lower half from the center line (CL) and when calculating the upper half, so the relative intensity of the light source the a _0, it is necessary to calculate 1/2 of the relative intensity of the light source placed at a position other than its.

  Therefore, the relative illuminance obtained by such a model is calculated over the entire area to be imaged (Ai).

Conventionally, practical reduction optical systems have been used in the range of W: Ld = 1: 1.5 to W: Ld = 1: 1 due to the relationship between image distortion caused by the imaging lens and brightness distribution. When W: Ld = 1: 1.5, θmax = 18.4 °, and when W: Ld = 1: 1, θmax = 26.6 °.
FIG. 25 shows a specific example of the relative brightness of an image formed on the one-dimensional CCD by the imaging lens in the imaging target area (Ai) illuminated with a constant illuminance when these practical reduction optical systems are used. FIG. 5 is a diagram illustrating a specific example of a target illuminance distribution (required illuminance distribution) when the imaging target area (Ai) is illuminated so that the relative brightness of an image formed on the one-dimensional CCD is constant.
The curve of the relative brightness of the image formed by the imaging lens on the one-dimensional CCD corresponding to each position in the imaging target area (Ai) in the case of W: Ld = 1: 1.5 is shown in FIG. It looks like the curve shown in (1). In addition, in the case of W: Ld = 1: 1, the relative brightness curve of the image formed by the imaging lens on the one-dimensional CCD corresponding to each position in the imaging target area (Ai) is shown in FIG. It looks like the curve shown in (2). As a result, in the case of W: Ld = 1: 1.5, the curve of the ratio of the illuminance required at any position of the imaging target area (Ai) with respect to the illuminance at the center of the imaging target area (Ai) is It becomes like the curve shown in (3) of FIG. 25, and the degree of illuminance that must be improved at both ends of the imaging target area (Ai) is 123% with respect to the illuminance at the center of the imaging target area (Ai). It is. In addition, in the case of W: Ld = 1: 1, the illuminance ratio curve required at any position of the imaging target area (Ai) with respect to the illuminance at the center of the imaging target area (Ai) is shown in FIG. The curve is as shown in (4), and the degree of illuminance that must be improved at both ends of the imaging target area (Ai) is 156% with respect to the illuminance at the center of the imaging target area (Ai).

FIG. 26 is a diagram illustrating a result of simulation toward the target relative illuminance for illuminating the imaging target area (Ai) according to the above-described concept. That is, the value of the relative illuminance I (Mm) obtained by the above-described equation and the difference between the relative illuminance I (Mm) and the required relative illuminance are expressed as A _k = 1, N = 12 (imaging target region ( The number of light sources that illuminate the entire area of Ai) = 25) and a = 2. However, FIG. 26A shows only the result in the case of W: Ld = 1: 1. FIG. 26B is a diagram (enlarged view) showing the difference between the calculation result of the relative illuminance I (Mm) and the required relative illuminance.

  In FIG. 26A, graph (1) shows the illuminance distribution in the entire imaging target region (Ai) illuminated by the light source in the region half from the center line (CL), and graph (2) shows The illuminance distribution in the entire imaging target area (Ai) illuminated by the light source in the half area on the opposite side of the graph (1) is shown. Graph (3) is the sum of graph (1) and graph (2). Graph (4) is normalized so that the central value of graph (3) is 100. Graph (5) is the difference between graph (4) in FIG. 26 (a) and graph (4) in FIG.

  In FIG. 26B, the graph (6) is the same as the graph (5), and the graph (7) shows the calculated relative illuminance and the target illuminance in the case of W: Ld = 1: 1.5. It is a difference.

The reason why the vicinity of both ends of the graph shown in FIG. 26B is disturbed and a large difference from the target illuminance occurs is that the light source from the position P _{n + 1} to the position P _{2n + 1} is from the position P ₀ as shown in FIG. This is because the distance between the light sources is not an ideal distance because it is a virtual light source that is a mirror image of the light source up to the position P _n . However, by appropriately setting the position of the side mirror between the position P _n and the position P _{n + 1 to} the P _n side or slightly changing the angle of the side mirror, the imaging target region (Ai) It is possible to control the illuminance distribution in the vicinity of both ends to some extent.

  However, the difference shown in the graph (7) is less than ± 1 (%), and the difference shown in the graph (6) is also less than ± 2 (%). That is, it can be seen that the relative illuminance of the imaging target area (Ai) illuminated by a plurality of light sources can be brought close to the target illuminance distribution with very high accuracy. Further, from the graph of FIG. 26B, the width of the region illuminated by the light source in the main scanning direction (Sx) is increased by about 2 to 3% (or illuminated by the light source in the main scanning direction (Sx)). By reducing the width of the imaging target area (Ai) by about 2 to 3%), the illuminance distribution of the imaging target area (Ai) illuminated by the light source can be further adapted to the target illuminance distribution, By setting appropriate conditions, it is possible to make the difference between the illuminance distribution of the imaging target area (Ai) illuminated by the light source and the target illuminance distribution less than ± 1%. However, in practice, the fluctuation of the illuminance distribution due to errors in parts accuracy or assembly accuracy is larger than the above difference, and the above difference is not a problem.

  Further, from the comparison of the graphs (6) and (7) in FIG. 26B, the distance from the imaging target area (Ai) to the imaging lens with respect to the width W of the imaging target area (Ai) in the main scanning direction (Sx). It can be seen that the larger the ratio of Ld, the easier it is to approach the target illuminance distribution.

Further, when a in cos ^a α that models the envelope of the radiation vector of the light source is set to a = 1 or a = 4 and a similar simulation is performed, from the illumination target surface (imaging region) (Ai) Although the optimum distance L0 to the light source slightly changed, substantially the same characteristics were obtained.

  In addition, here, it is assumed that a light source is placed on the center line of the imaging target area (Ai), and the entire imaging target area (Ai) is illuminated with an odd number of light sources, but the imaging target area (Ai) It goes without saying that the entire illumination target area (Ai) can be illuminated with an even number of light sources without placing a light source on the center line, and a similar simulation or design is possible.

Next, an example of an illuminating device that matches the illuminance distribution of the light that illuminates the imaging target area (Ai) with the 1 / cos ⁴ θ characteristic by adjusting the interval between the plurality of light sources will be described.

FIG. 27 is a conceptual diagram for realizing an illuminating device that matches the illuminance distribution of the light that illuminates the imaging target region (Ai) with the 1 / cos ⁴ θ characteristic by adjusting the interval between the plurality of light sources. . FIG. 27 (a) by adjusting the spacing of a plurality of light sources, in a top view of an example of a lighting device to match the illuminance distribution of the light illuminating the image capturing target area (Ai) to the characteristics of 1 / cos ⁴ θ Yes, it shows one of the peripheral parts of the imaging target area (Ai) (the other peripheral part is omitted from the central part). FIG. 27B shows an example of an illuminating device that matches the illuminance distribution of the light that illuminates the imaging region (imaging target region) (Ai) with the 1 / cos ⁴ θ characteristic by adjusting the interval between the plurality of light sources. FIG.

As shown to Fig.27 (a), an illuminating device contains several LED arranged in the main scanning direction (Sx) as several light sources. The luminous flux of light emitted from each LED is collimated by a hood lens that is a convex lens corresponding to the LED, then once condensed by an illumination lens (3) that is a cylinder lens, and then diverged. Illuminates the illumination target area (Ai). Here, the plurality of LEDs are arranged so that the interval between the plurality of LEDs becomes narrower from the vicinity of the center line of the lighting device toward the periphery of the lighting device in accordance with the result of the simulation described above. (The order of the number k of the LED spacing w _k in FIG. 27A is opposite to the order of the number k of the spacing w _k in FIG. 23.) Note that from the imaging target region (Ai) shown in FIG. The positions P _{0 to} P _n of the respective light sources separated by the distance L ₀ correspond to the focal position (focal length f) of the cylinder lens corresponding to each LED in the illumination device shown in FIG. That is, the position of the focus of the cylinder lens corresponding to each LED can be regarded as the position of a virtual light source.

  Further, the configuration of the illumination device in the eleventh embodiment in the sub-scanning direction (Sy) needs to change the configuration of the illumination device in the first to ninth embodiments of the present invention in the sub-scanning direction (Sy). There is no. In FIG. 27 (b), light beams emitted from individual LEDs are converted into parallel light by a hood lens corresponding to the LED, and then transmitted through the illumination lens (3), which is a cylinder lens, as parallel light. The method of focusing on the illumination target area (Ai) by the focusing mirror (4b) is shown. Here, it should be noted that the use of a plane mirror instead of the focusing mirror to irradiate the imaging target area (Ai) as parallel light does not deviate from the simulation results described above.

  In FIG. 27, a hood lens that is a convex lens is used as means for collimating the light emitted from the LED of the light source. However, instead of the hood lens, a rotary parabolic mirror as shown in FIG. May be used.

  Further, in the method or apparatus configuration of the first to ninth embodiments of the present invention, the interval between the plurality of light sources arranged in the main scanning direction (Sx) may be changed according to the simulation result as described above. Good.

  Further, in the fifth and sixth embodiments of the present invention, a set of red (R), green (G), and blue (B) LEDs is used as a light source. Similarly, in the eleventh embodiment of the present invention, the interval between the red (R), green (G), and blue (B) LED sets may be changed in accordance with the simulation results described above.

In the twelfth embodiment of the present invention, the illuminance distribution of the light that illuminates the imaging target area (Ai) by adjusting the distance from each of the plurality of light sources to the imaging target area (Ai) is expressed by the characteristic of 1 / cos ⁴ θ. An example of matching is shown.

  FIG. 28 is a diagram for explaining how to obtain a specific arrangement of a plurality of light sources that illuminate the imaging target area (Ai) so that the relative brightness of an image formed on the one-dimensional CCD is constant. FIG. 28A is a diagram showing the arrangement of a plurality of light sources and the position of the mirror surface on which the side mirror is arranged, and FIG. 28B is a diagram showing an example of the radiation characteristics of the light sources.

In the diagram shown in FIG. 28A, the intervals between the plurality of light sources in the main scanning direction (Sx) are constant, but the distance from each of the plurality of light sources to the illumination target region (imaging target region) (Ai). To change. The symbols in FIG. 28 are the same as those in FIG. 24, but in FIG. 28A, the intervals w1, w2,... Wn of the plurality of light sources are constant and equal to Wh / N. In other words, the intervals w1, w2,... Wn of the plurality of light sources are given by dividing the half Wh of the length of the imaging target area (Ai) in the main scanning direction (Sx) into N equal parts. Further, among the plurality of light sources, the distance L _k from the light source arranged at the k-th position P _k to the illumination target surface (imaging region) (Ai) is expressed by the following equation:

It is decided according to. Here, θ _k is an angle of a straight line connecting the center of the imaging lens and the kth division point on the imaging target area (Ai) with respect to the optical axis of the imaging lens. That is, the distance Lk from the light source arranged in k-th position P _k of the plurality of light sources to the illumination target surface (imaging region) (Ai), in accordance with the cosine fourth power law with respect to theta _k, imaging By reducing the brightness of the image formed by the lens by reducing the distance L ₀ from the position P _{0 of} the light source provided on the optical axis of the imaging lens to the imaging target area (Ai) to the distance L _k . To compensate.

  Further, the relative illuminance I (Mm) at an arbitrary point Mm in the imaging target area (Ai) irradiated with light emitted from a plurality of light sources is expressed by the same concept as in the eleventh embodiment of the present invention.

Sought by.

  FIG. 29 is a diagram showing the difference between the calculation result of the relative illuminance I (Mm) and the required relative illuminance among the simulation results of the relative illuminance in the twelfth and subsequent embodiments of the present invention.

  In the twelfth embodiment of the present invention, under the conditions described above, by the same method as the eleventh embodiment of the present invention, a plurality of light sources are used under the condition of W: Ld = 1: 1. The illuminance distribution was simulated over the entire area to be imaged (Ai) to be illuminated. As a result, a graph similar to that in FIG. 26 was obtained. Of these, the graph showing the illuminance distribution as a result of the simulation is very similar to the graph of FIG. 26 (a), so it is not shown, and the difference between the illuminance distribution and the target illuminance distribution is omitted. Only the enlarged view is shown in the curve of (1) in FIG.

The reason why the vicinity of both ends of the curve (1) in FIG. 29 is disturbed and a large difference from the target illuminance is generated is similar to the reason of the twelfth embodiment, from the position P _{n + 1} to the position P _{2n + 1.} This is because the distance between the imaging target area (Ai) and the light source cannot be set to an ideal distance because the light source is a virtual light source that is a mirror image of the light source from the position P ₀ to the position P _n . However, by appropriately setting the position of the side mirror between the position P _n and the position P _{n + 1 to} the P _n side or slightly changing the angle of the side mirror, the imaging target region (Ai) It is possible to control the illuminance distribution in the vicinity of both ends to some extent.
However, even if it remains as it is, the maximum value of the difference shown in the graph (1) of FIG. 29 is about ± 3%, which is about twice the maximum value of the difference shown in FIG. From the viewpoint of assembly accuracy and energy saving, there is almost no problem. (Even if the gain of the electrical signal after the light amount is converted into an electrical signal by the one-dimensional CCD is changed and the difference is corrected, the change of the gain is small and is not affected by noise.)
Next, a concept for making a lighting device based on the above concept will be described.

In FIG. 30, the illuminance distribution of the light that illuminates the imaging region (Ai) is adjusted to a 1 / cos ⁴ θ characteristic by adjusting the distance from each of the plurality of light sources to the imaging region (imaging target region) (Ai). It is a conceptual diagram for implement | achieving the illuminating device made to correspond. FIG. 30A is a top view thereof, and FIG. 30B is a front view thereof. Note that the method of embodying the concept shown in FIG. 30 and mounting it on the first traveling body is in accordance with the method of Example 11 described above, and can be easily implemented by those skilled in the art.

  FIG. 31 is a diagram illustrating an example of a method for changing the radiation characteristic of light emitted from a light source. FIG. 31 is a view seen from the same direction as the top view shown in FIG. In FIG. 31, a front view is omitted, but the same configuration as FIG.

  Here, as shown in FIG. 31 (1), the light emitting source LED is placed at the focal point of the convex lens (focal length f0) which is also a hood. A convex cylinder lens (focal length f1) having the same focal length as the convex lens is disposed on the front surface of the convex lens so that the optical axis of the convex lens coincides with the optical axis of the convex cylinder lens. At this time, a virtual light source having radiation characteristics similar to the radiation characteristics of the light source can be formed at the focal position of the convex cylinder lens. For example, as shown in (1) of FIG. 28B, when the envelope of the emission characteristic of the light source is circular, a virtual light source having the emission characteristic of the same circular envelope can be formed at the point F. it can. Next, if the focal length f1 of the convex cylinder lens is made smaller than the focal length f0 of the convex lens by using the light emitting source having the same circular envelope envelope emission characteristic, as shown in FIG. It is possible to form a virtual light source having the radiation characteristic of an elliptical envelope that is flat in the axial direction. On the other hand, when f1> f0, as shown in (3) of FIG. 31, a virtual light source having the radiation characteristic of an elliptical envelope that is sharp in the direction of the optical axis can be formed. (However, in reality, there is no light flux going outside the arrow in the figure due to the size of the hood lens and the critical angle).

In FIG. 30A, the relationship between the shape of the convex lens and the shape of the convex cylinder lens is any one of (1), (2), and (3) in FIG. Arranged in the direction (Sx). In FIG. 30 (a), light fluxes emitted from individual light emitting sources LED are collimated by a corresponding hood lens that is a convex lens and then collected by an illumination lens (3) that is a convex cylinder lens. Light and diverge. In the twelfth embodiment of the present invention, the peripheral side of the imaging region (Ai) rather than the focal point position (virtual light source position) of the convex cylinder lens arranged on the center line side of the imaging region (Ai). The combination of the light source LED, the convex lens, and the convex cylinder lens is disposed so that the focal position (the position of the virtual light source) of the convex cylinder lens disposed in the position is close to the imaging region (Ai). More specifically, the distance between the imaging region (Ai) and the focal position (imaginary light source position) of the convex cylinder lens is the relative brightness of the image formed on the one-dimensional CCD by the imaging lens. Is proportional and is given by the equation L ₀ × cos ⁴ θ described above. In FIG. 30A, the number of light sources is 10, but in the simulation, the number of light sources was set to 25.

  In FIG. 30B, only the combination of the light source, the convex lens, and the convex cylinder lens at the center and one end in the main scanning direction (Sx) is shown, and the other light source, convex lens, and convex cylinder lens are shown. Is omitted. As shown in FIG. 30 (b), in the sub-scanning direction (Sy), the light flux emitted from each light emitting source LED is converted into parallel light by a hood lens that is a convex lens corresponding to the LED. Then, the light passes through the illumination lens (3), which is a convex cylinder lens, as parallel light, and is focused on the imaging region (imaging target region) (Ai) by the focusing lens (4a) (or the focusing mirror). The distance from the imaging region (Ai) to the light source varies between the central portion and the peripheral portion in the main scanning direction (Sx), but from the focusing lens (4a) (or the focusing mirror) to the imaging region (Ai). Therefore, the degree of focusing of the light emitted from the light emitting source LED does not vary depending on the position of the light source in the main scanning direction (Sx). In other words, in the sub-scanning direction (Sy), the distance from the illumination lens (3) to the focusing lens (4a) (or the focusing mirror) varies, but the luminous flux is from the illumination lens (3) to the focusing lens (4a). It is parallel light up to (or the focusing mirror). Further, since the distance from the focusing lens (4a) (or the focusing mirror) to the imaging region (Ai) where the light beam is focused is constant, the degree of focusing of the light does not vary. Note that it is not always necessary to insert the focusing lens (4a) (or the focusing mirror). That is, when taking into consideration the floating of the document, it is preferable not to use the focusing lens (4a) (or the focusing mirror). However, even in this case, the purpose of making the relative brightness of the image formed on the one-dimensional CCD constant is not impaired.

The thirteenth embodiment of the present invention is an example in which the illuminance distribution of light that illuminates the imaging target area (Ai) is adjusted to the 1 / cos ⁴ θ characteristic by adjusting the radiation characteristics of light emitted from a plurality of light sources. Indicates.

  FIG. 32 is a diagram for explaining a specific arrangement of a plurality of light sources that illuminate the imaging target region so that the relative brightness of an image formed on the one-dimensional CCD is constant. FIG. 32A is a diagram showing the arrangement of a plurality of light sources and the position of the mirror surface on which the side mirror is arranged, and FIG. 32B is a diagram showing an example of the radiation characteristics of the light sources.

The symbols in FIG. 32 are the same as the symbols in FIG. 24, but the distance between the plurality of light sources in the main scanning direction (Sx) and the distance from each of the plurality of light sources to the illumination target region (imaging target region) (Ai) are as follows. Is constant. That is, in FIG. 32A, the intervals w1, w2,... Wn of the plurality of light sources are constant and equal to Wh / N. In other words, the intervals w1, w2,... Wn of the plurality of light sources are given by dividing the half Wh of the length of the imaging target area (Ai) in the main scanning direction (Sx) into N equal parts. The distance from each of the plurality of light sources to the illumination target area (imaging target region) (Ai) is L _0. However, the radiation characteristics of the light emitted from each light source are changed.

How to make that change is explained. That is, assuming that the total amount of light emitted from the light source is the same, the luminous flux is more dispersed in the area where the illuminance is reduced, and the luminous flux is less dispersed in the area where the illuminance is increased. The degree of dispersion of the luminous flux can be approximated by the radiation characteristic equation cos ^a α. When the representative is represented by a figure or an equation, when actively dispersing as shown in FIG. 32 (b), FIG. 32 (1) a When the degree of dispersion is suppressed as in = 1 (cos ^0.5 α), FIG. 32 (3) a = 2 (cos ² α). FIG. 32 (2) a = 1 (cos α) is in the middle. What is important here is that if the total amount of light emitted from the light source is constant, the area surrounded by the envelope of the light radiation vector is constant even if a changes.

Here, the newly Tk relative value of the target illuminance at any division point (the division points corresponding to the k-th position P _k of the plurality of light sources) of the imaging target region (Ai). That is, the target value Tk is changed again according to the cosine fourth law.

And Here, θ _k is an angle of a straight line connecting the center of the imaging lens and the kth division point on the imaging target area (Ai) with respect to the optical axis of the imaging lens. Further, the radiation characteristic of the light emitted from the light source arranged at the k-th position P _k among the plurality of light sources is expressed by

Set according to. In the equation, T _k ² is the intensity of a vector in the vertical direction with respect to the illumination target surface (imaging region) (Ai) among the radiation vectors of light emitted from the light source at the k-th position P _k. B (k) is a function that defines the shape of the radiation characteristic (envelope) of the radiation vector of the light emitted from the light source at the k-th position P _k , and B (k) = a · T _k ^b It is represented by Here, a is an initial value (initial value of the shape of the radiation characteristic), and b is a shape factor (a parameter that defines the degree of change in the shape). That is, for k = 0, the shape of the radiation characteristic of the light emitted from the light source at position P ₀ is B (k = 0) = a, and as shown in FIG. Determined uniquely.

  Therefore, the relative illuminance I (Mm) at an arbitrary point Mm in the imaging target area (Ai) irradiated with light emitted from a plurality of light sources is expressed in the same way as in the twelfth embodiment of the present invention.

Represented by

  Using this equation, N = 12, a = 0.5, b = 3.1, and the imaging target area (Ai) illuminated by a plurality of light sources in the same manner as in the eleventh embodiment of the present invention. As a result of obtaining the illuminance distribution over the entire area, a graph similar to FIG. 26 could be obtained. Among them, the difference between the illuminance distribution and the target illuminance distribution as a result of the simulation performed under the condition of W: Ld = 1: 1 is as shown in the graph (2) in FIG.

The reason why the vicinity of both ends of the curve (2) in FIG. 29 is disturbed and a large difference from the target illuminance occurs is similar to the reason of the twelfth embodiment, from the position P _{n + 1} to the position P _{2n + 1.} This is because the light source is a virtual light source that is a mirror image of the light source from the position P ₀ to the position P _n, and thus the light emission characteristic of the light source is not ideal. However, by appropriately setting the position of the side mirror between the position P _n and the position P _{n + 1 to} the P _n side or slightly changing the angle of the side mirror, the imaging target region (Ai) It is possible to control the illuminance distribution in the vicinity of both ends to some extent.

However, even if it remains as it is, the maximum value of the difference is about ± 5%, which is slightly larger than the maximum value of the difference shown in the graph (1) of FIG. However, the maximum value of such a difference hardly poses any problem from the viewpoints of component accuracy, assembly accuracy, and energy saving. (Even if the gain of the electrical signal after changing the amount of light into an electrical signal with a one-dimensional CCD is changed and the difference is corrected, the change in the gain is small and is hardly affected by noise.)
Next, an illumination device that matches the illuminance distribution of the light that illuminates the imaging target region (Ai) with the 1 / cos ⁴ θ characteristic by adjusting the radiation characteristics of the light emitted from the plurality of light sources described above. The concept to realize is shown.

33 by adjusting the radiation characteristic of light emitted from the plurality of light sources, realized an illumination device for matching the illuminance distribution of the light illuminating the imaging area (imaging target region) on the characteristics of 1 / cos ⁴ θ It is a conceptual diagram for doing. FIG. 33 (a) is a top view thereof, and FIG. 33 (b) is a front view thereof.

  In the diagram shown in FIG. 33A, the focal lengths of the convex lenses corresponding to the plurality of light sources arranged in the main scanning direction (Sx) are constant, and the plurality of light sources arranged in the main scanning direction (Sx). The focal length of the illumination lens (convex cylinder lens) (3) corresponding to is changed as shown in FIG. In the vicinity of the center of the illumination device shown in FIG. 33A, the envelope of the radiation characteristic of the virtual light source formed at the focal position of the illumination lens is a flat ellipse with strong dispersion as shown in FIG. As shown in FIG. 33 (1), an illumination lens having a relatively short focal length is used so that the focal length is gradually increased toward the periphery so as to reduce the flatness. After using an illumination lens having an almost circular envelope, an illumination lens having a relatively long focal length is used so as to form a sharp ellipse with little dispersion, as shown in FIG. 31 (3).

In other words, the shape of the elliptical envelope of the radiation characteristic of the virtual light source formed at the focal position of the illumination lens is changed in accordance with the above-described equation R _k = T _k ² · cos ^{B (k)} α _k .

  In addition, by changing the focal length of the illumination lens so that the shape of the elliptical envelope of the radiation characteristics of the virtual light source formed at the focal position of the illumination lens changes, the distance from the light source to the virtual light source can also be changed. It fluctuates between the vicinity of the center and the vicinity of the lighting device. Therefore, in order to make the distance from the virtual light source to the illumination target surface (imaging region) (Ai) constant, the position of the light source LED is varied between the vicinity of the center of the illumination device and the vicinity of the periphery. . In the simulation, the number of light sources is 25, but in FIG. 33 (a), the number of light sources is 10.

In FIG. 33B, only the combination of the light source, the convex lens, and the convex cylinder lens at the center and one end in the main scanning direction (Sx) is shown, and the other light source, convex lens, and convex cylinder lens are shown. Is omitted. As shown in FIG. 33 (b), in the sub-scanning direction (Sy), the light flux emitted from each light emitting source LED is converted into parallel light by a hood lens that is a convex lens corresponding to the LED. Then, it passes through the illumination lens (3), which is a convex cylinder lens, as parallel light, and is focused on the imaging region (Ai) by the focusing lens (4a) (or focusing mirror). The distance from the imaging region (Ai) to the light source varies between the central portion and the peripheral portion in the main scanning direction (Sx), but from the focusing lens (4a) (or the focusing mirror) to the imaging region (Ai). Therefore, the degree of focusing of the light emitted from the light emitting source LED does not vary depending on the position of the light source in the main scanning direction (Sx). In other words, in the sub-scanning direction (Sy), the distance from the illumination lens to the focusing lens (4a) (or focusing mirror) varies, but the luminous flux is from the illumination lens to the focusing lens (4a) (or focusing mirror). It is parallel light in between. Further, since the distance from the focusing lens (4a) (or the focusing mirror) to the imaging region (Ai) where the light beam is focused is constant, the degree of focusing of the light does not vary. Note that it is not always necessary to insert the focusing lens (4a) (or the focusing mirror). That is, when taking into consideration the floating of the document, it is preferable not to use the focusing lens (4a) (or the focusing mirror). However, even in this case, the purpose of making the brightness of the image formed on the one-dimensional CCD constant is not impaired.
Note that the method of embodying the concept shown in FIG. 33 and mounting it on the first traveling body is in accordance with the method of Example 11 described above, and can be easily implemented by those skilled in the art.

The fourteenth embodiment of the present invention shows an example of the concept of an illumination device that approximates the illuminance distribution of light that illuminates the imaging region (imaging target region) (Ai) to the characteristic of 1 / cos ⁴ θ.

FIG. 34 shows an illumination device that approximates the illuminance distribution of light that illuminates the imaging region (Ai) to the 1 / cos ⁴ θ characteristic by adjusting the distance from each of the plurality of light sources to the imaging region (Ai). It is a conceptual diagram for implement | achieving. FIG. 34 (a) is a top view thereof, and FIG. 34 (b) is a front view thereof. FIG. 34C is a diagram illustrating an example of an illuminance distribution of light that illuminates the imaging region approximated to the characteristic of 1 / cos ⁴ θ.

In the twelfth embodiment of the present invention, by adjusting the distance from each of the plurality of light sources to the imaging region (Ai), the illuminance distribution of the light that illuminates the imaging region (Ai) is represented by the 1 / cos ⁴ θ characteristic. An example of a lighting device that matches with better accuracy has been described. Considering a configuration that can be manufactured more easily, for example, by sacrificing the accuracy of the illuminance distribution of the light that illuminates the imaging region (Ai) that should have the characteristic of 1 / cos ⁴ θ. it can. The lighting device according to the embodiment of the present invention shown in FIG. 34 can be more easily manufactured than the lighting device described in the twelfth embodiment of the present invention.

First, as shown in FIG. 34 (c), it gives the ideal illuminance distribution in the image pickup area including the first 12 characteristic of 1 / cos ⁴ θ in the embodiment of the present invention (Ai), a plurality of light sources relative A curve of a typical position L _k / L ₀ = cos ⁴ θ is divided into three (3 Dev) within the imaging area (Ai). And it approximates to the trapezoid (Pa-Pb-Pc-Pd) which makes the point (Pb, Pc) on the curve in the position which divided the curve into three into a vertex. Then, a light source is arranged on each side (Pa-Pb, Pb-Pc, Pc-Pd) of the trapezoid (congruent trapezoid), or each side (Pa- The light source is arranged so that the virtual light source is positioned on (Pb, Pb-Pc, Pc-Pd). When the curve of cos ⁴ θ indicating the relative positions of a plurality of light sources is approximated to a trapezoid, the difference between the ideal illuminance distribution and the illuminance distribution of the approximate configuration is the ideal cos ⁴ of the plurality of light sources. It is only based on the difference between the position on the curve of θ and the position on the side of the trapezoid of the plurality of light sources, and is very small.

  FIG. 34A illustrates an illumination device that approximates the target illuminance distribution of light that illuminates the imaging region (Ai) with a trapezoidal characteristic by adjusting the distance from each of the plurality of light sources to the imaging region (Ai). The concept of As shown in FIG. 34A, for example, a light source that gives a trapezoidal side characteristic parallel to the imaging region (Ai) in the trapezoidal characteristic is a light source or a virtual light source (here, the illumination lens (3)). The focal point is placed on a trapezoidal side parallel to the imaging region (Ai). Further, for example, the light source that gives the characteristic of the side inclined with respect to the imaging region (Ai) in the trapezoidal characteristic is the light source or the virtual light source (here, the focal point of the illumination lens (3)) in the imaging region (Ai). The prism (7) is provided on the imaging region (Ai) side of the illumination lens (3) that is a cylinder lens, which is arranged in parallel with the inclined side. The optical axis extending from the light source or the virtual light source is bent by the prism (7) by the prism (7) provided on the imaging area (Ai) side of the illumination lens (3), and the bent optical axis is changed to the imaging area ( Be perpendicular to Ai).

  By adopting a configuration as shown in FIG. 34, a flat plate can be used as the substrate for supporting the light source, and the manufacture of the lighting device becomes easier.

In FIGS. 34 (a) and 34 (b), a rotating paraboloidal mirror is used to make the light emitted from the light emitting source LED into parallel light, but a bullet-type hood lens may be used. Further, in FIG. 34 at the expense of a little efficiency, 1 / cos ⁴ gives an ideal irradiance distribution in the imaging area (Ai) having the characteristics of theta, the relative positions of the plurality of light sources curve cos ⁴ theta Is divided into three in the range of the imaging region (Ai), but may be divided into two in the range of the imaging region (Ai) if the efficiency may be further sacrificed. And you may approximate the curve of the relative position of a some light source to the triangle which makes the point on the curve in the position which divided | segmented the curve into two the vertex. In this case, the plurality of light sources are arranged only on the side inclined with respect to the imaging region (Ai). As described above, even when the curve of the relative position of a plurality of light sources is approximated to a triangle by dividing into two in the range of the imaging region (Ai), compared to the case where the imaging region (Ai) is illuminated uniformly, The utilization efficiency of light emitted from the light source can be greatly improved.

Similarly, in the thirteenth embodiment of the present invention, a curve of the relative positions of a plurality of light sources giving an ideal illuminance distribution in the imaging region (Ai) having the characteristic of 1 / cos ⁴ θ is It is possible to approximate a polygon in the range of the imaging area (Ai). For example, a relative position curve of a plurality of light sources that gives an ideal illuminance distribution in the imaging region (Ai) having the characteristic of 1 / cos ⁴ θ in the thirteenth embodiment of the present invention is shown in FIG. You may approximate to the trapezoid or triangle which has a vertex in the position on the opposite side with respect to the surface parallel to an imaging area | region (Ai) and the position of the approximate trapezoid or triangle vertex in 12th Example. In this case, a flat plate can be used as the substrate that supports the light source, and the manufacture of the lighting device becomes easier.

  In addition, in the illuminating device shown in FIG. 34, when the light emission source is a combination of red (R), green (G), and blue (B) LEDs, it is between red light, green light, and blue light by the prism. Causes chromatic aberration. However, the red light, the green light, and the blue light that have passed through the plurality of prisms are superimposed on each other in the imaging region (Ai), and substantially white light illumination is provided to the imaging region (Ai). Therefore, in practice, chromatic aberration due to the prism is rarely a problem.

Note that discarding the light flux at the center of the imaging region (Ai) having a substantially constant illuminance distribution in the prior art means discarding a large amount of light (the amount of light in the hatched portion) shown in FIG. become. On the other hand, according to the fourteenth embodiment of the present invention, only a small amount of light in the portion sandwiched between the target position curve and the trapezoidal approximate polygonal line is discarded. Therefore, according to the fourteenth embodiment of the present invention, the electrical correction of the electrical signal corresponding to the amount of light is slight, and the influence of noise on the electrical signal can be reduced as compared with the prior art.
Note that the method of embodying the concept shown in FIG. 34 described above and mounting it on the first traveling body is also in accordance with the method of Example 11 described above, and can be easily implemented by those skilled in the art.

In the fifteenth embodiment of the present invention, the light that illuminates the imaging region by both adjusting the distance from each of the plurality of light sources to the imaging region (Ai) and adjusting the radiation characteristics of the light emitted from the plurality of light sources. An example of matching the illuminance distribution with the 1 / cos ⁴ θ characteristic is shown.

  FIG. 35 is a diagram illustrating a specific arrangement of a plurality of light sources that illuminate the imaging target area (Ai) so that the relative brightness of an image formed on the one-dimensional CCD is constant. FIG. 35A is a diagram showing the arrangement of a plurality of light sources and the position of the mirror surface on which the side mirror is arranged, and FIG. 35B is a diagram showing an example of the radiation characteristics of the light sources.

  In the diagram shown in FIG. 35A, the distance between the plurality of light sources in the main scanning direction (Sx) is constant, but the distance from each of the plurality of light sources to the illumination target area (imaging target area) (Ai). And changing the radiation characteristics of the light emitted from the plurality of light sources. The meanings of the symbols in FIG. 35 are the same as the symbols in FIG. 24, and the intervals w1, w2,. In other words, the intervals w1, w2,... Wn of the plurality of light sources are given by dividing the half Wh of the length of the imaging target area (Ai) in the main scanning direction (Sx) into N equal parts.

In the diagram shown in FIG. 35A, the distance L ′ _k from the imaging target area (Ai) to the position P _k of the k-th light source is the expression L _k = L × in the twelfth embodiment of the present invention. midway between the distance _{L 0} from the position _{P 0} of the light source provided on the center line of the values obtained by cos ⁴ θ _{k L k} and the imaging target area (Ai) to the illumination target surface (imaging area (Ai)) Distance. That is, the distance L ′ _k from the imaging target area (Ai) to the position P _k of the _kth light source is

Is the distance obtained. (Here, θ _k is an angle of a straight line connecting the center of the imaging lens and the kth division point on the imaging target area (Ai) with respect to the optical axis of the imaging lens.)
In addition, assuming that the total amount of light emitted by each light source is the same, the emission characteristics of light emitted from the light source (from the light source) The intensity of the radiation vector with respect to the angle of the radiation vector of the emitted light is changed. The degree of change is half that of the thirteenth embodiment of the present invention. That is,

And the shape factor b of B (k) in the equation is half the value of b in the thirteenth embodiment of the present invention.

  Under such conditions, the relative illuminance I (Mm) at an arbitrary point Mm in the imaging target area (Ai) irradiated with light emitted from a plurality of light sources is the same as that of the twelfth embodiment of the present invention. In the same way, the formula

Represented by

  Using this equation, the illuminance distribution over the entire imaging target area (Ai) illuminated by a plurality of light sources was obtained in the same manner as in the eleventh embodiment of the present invention. As a result of simulation under the conditions of N = 12, a = 0.5, and b = 1.55, a graph similar to FIG. 26 was obtained. Further, the difference between the illuminance distribution and the target illuminance distribution as a result of the simulation of the illuminance distribution over the entire imaging target area (Ai) illuminated by a plurality of light sources performed under the condition of W: Ld = 1: 1. Was like the graph (3) of FIG.

The reason why the vicinity of both ends of the curve (3) in FIG. 29 is disturbed and a large difference from the target illuminance occurs is similar to the reason of the twelfth embodiment, from the position P _{n + 1} to the position P _{2n + 1.} Is a virtual light source that is a mirror image of the light source from the position P ₀ to the position P _n , the distance between the imaging target area (Ai) and the light source and the light emission characteristics of the light source cannot be set ideally. It is. However, by appropriately setting the position of the side mirror between the position P _n and the position P _{n + 1 to} the P _n side or slightly changing the angle of the side mirror, the imaging target region (Ai) It is possible to control the illuminance distribution in the vicinity of both ends to some extent.

  However, even if it remains as it is, the maximum value of the difference is about ± 2.5%, which is smaller than the maximum value of the difference shown in the graphs (1) and (2) of FIG. Moreover, although it is larger than the maximum value of the difference shown in FIG. 26, such a maximum value of the difference hardly poses any problem from the viewpoint of the accuracy of parts, the accuracy of assembly, and the viewpoint of energy saving. Even if the gain of the electrical signal after changing the amount of light into an electrical signal with the one-dimensional CCD is changed and the difference is corrected, the amount of change in the gain is small and is hardly affected by noise.

Next, by adjusting both the distance from each of the plurality of light sources to the imaging region and the adjustment of the radiation characteristics of the light emitted from the plurality of light sources, the illuminance distribution of the light that illuminates the imaging region is 1 / cos ⁴ θ. The concept of lighting equipment matching the characteristics is shown.

FIG. 36 shows the illuminance of light that illuminates the imaging region (Ai) by adjusting both the distance from each of the plurality of light sources to the imaging region (Ai) and adjusting the radiation characteristics of light emitted from the plurality of light sources. It is a conceptual diagram for implement | achieving the illuminating device which matches distribution with the characteristic of 1 / cos < ⁴ > (theta). FIG. 36 (a) is a top view thereof, and FIG. 36 (b) is a front view thereof.

As shown in FIG. 36A, the virtual light source and the imaging area (Ai) with respect to the distance L0 between the virtual light source and the imaging area (Ai) along the central axis in the imaging area (imaging target area) (Ai). the distance L between the 'ratio _k is the square root of the 14 values ^{_{L k / L0 = cos 4 θ}} k obtained in example of the present invention, i.e., L' is ^{_{k / L0 = cos 2 θ k}} .

  In the diagram shown in FIG. 36A, the focal lengths of the convex lenses corresponding to the plurality of light sources arranged in the main scanning direction (Sx) are constant, and the plurality of light sources arranged in the main scanning direction (Sx). The focal length of the illumination lens (convex cylinder lens) (3) corresponding to is changed as shown in FIG. In the vicinity of the center of the illumination device shown in FIG. 36A, the envelope of the radiation characteristic of the virtual light source formed at the focal position of the illumination lens is a flat ellipse with strong dispersion as shown in FIG. As shown in FIG. 33 (1), an illumination lens having a relatively short focal length is used so that the focal length is gradually increased toward the periphery so as to reduce the flatness. After using an illumination lens having an almost circular envelope, an illumination lens having a relatively long focal length is used so as to form a sharp ellipse with little dispersion, as shown in FIG. 31 (3).

That is, the shape of the elliptical envelope of the radiation characteristic of the virtual light source formed at the focal position of the illumination lens is changed in accordance with the above-described equation R ′ _k = T _k · cos ^{B (k)} α _k .

  In the case of the lighting device with the concept shown in FIG. 36, each light source can be arranged so that the distance from the position of each light source to the illumination target surface (imaging region) (Ai) is constant. A light source can be provided on the flat plate. As a result, the lighting device can be manufactured more easily. Although the simulation was performed with the number of light sources set to 25, the number of light sources is shown as 10 in FIG.

As shown in FIG. 36 (b), in the sub-scanning direction (Sy), the light flux emitted from each light emitting source LED is converted into parallel light by a hood lens that is a convex lens corresponding to the LED. Then, the light passes through the illumination lens, which is a convex cylinder lens, as parallel light, and is focused on the imaging target area (Ai) by the focusing lens (4a) (or the focusing mirror). Note that it is not always necessary to insert the focusing lens (4a) (or the focusing mirror). That is, it is preferable not to use a converging lens (or a converging mirror) in consideration of the floating of the original. However, even in this case, the purpose of making the brightness of the image formed on the one-dimensional CCD constant is not impaired.
Note that the method of embodying the concept shown in FIG. 36 and mounting it on the first traveling body is in accordance with the method of the above-described Embodiment 11, and can be easily implemented by those skilled in the art.

In the sixteenth embodiment of the present invention, an illumination optical axis angle of light emitted from a plurality of light sources is adjusted to match the illuminance distribution of the light that illuminates the imaging region with the 1 / cos ⁴ θ characteristic. Show.

  FIG. 37 is a diagram illustrating a specific arrangement of a plurality of light sources that illuminate the imaging target area (Ai) so that the relative brightness of an image formed on the one-dimensional CCD is constant. FIG. 37 corresponds to an enlarged view on the left side of the imaging target surface in FIG. The symbols in FIG. 37 correspond to the symbols in FIG.

As shown in FIG. 37, in the sixteenth embodiment of the present invention, the illuminance distribution in the imaging target area (Ai) has the characteristic of 1 / cos ⁴ θ, and the individual illumination optical axes of the plurality of light sources are Adjust the angle.

In the same manner as described in the above-described embodiments 11 to 15, each division point obtained by dividing the place separated from the illumination target area (Ai) by L0 and parallel to the illumination target area (Ai) by N. Place the two points light source, the position of each division point, _{respectively,} P _0, P 1, ... and _{P n.} Further, a mirror surface (side mirror) is disposed at the position of the outside PM1. This mirror surface reflects light beams emitted from a plurality of light sources placed on the light source arrangement position corresponding to the points obtained by dividing the range of the imaging target area (Ai), as if the light source is on the extended line. Is irradiated with the range of the illumination target area (Ai). Here, the positions of the virtual images (virtual light sources VLS) obtained by the side mirrors corresponding to the positions of the dividing points P _n ,..., P ₁ , P ₀ are P _{n + 1} , P _{n + 2 ,.} In the sixteenth embodiment of the present invention, the illumination optical axis of the light emitted from the light source located at the position P _k is set to an angle β _{k with} respect to the vertical direction of the illumination target surface (imaging region) (Ai). (The angle of the optical axis of the light source at the position P _k is β _k ).

Now, when an arbitrary point P00 is placed on the center line CL of the irradiation target area farther than the distance L0 from the illumination target area (Ai) to each light source (the distance is L00), the arbitrary point P00 Let β ₀₀ be the angle between a straight line connected from the point P00 toward both ends of the illumination target area and the center line CL. In this case, the angle beta _k of the illumination optical axis of the light source at the position P _k to be included within the scope of the angle beta ₀₀ from the center line CL is a straight line tied toward the point P00 to the position P _k of the light source, imaging It is assumed that the angle is made with the center line CL of the target area (Ai). On the other hand, the angle β _k of the illumination optical axis of the light source located outside the range from the center line CL of the imaging target area (Ai) to the angle β ₀₀ is all the position of the light source and the imaging target area (Ai). It is assumed that the straight line connecting the endmost part is an angle formed with the center line CL of the imaging target area (Ai). That is, with respect to the center line CL of the image capturing target area (Ai), the angle of the illumination optical axis of the light source at the position _{P k} is because it is _{β k, β 0, β 1} , ..., β k, ..., are beta _n .

Here, the angle beta _k of the illumination optical axis with respect to the light source position _{P k} from the center line CL to an angle beta ₀₀ in the image capturing target area (Ai) starts at _{k = 0 (β 0 = 0} ), increases with k increases made, but the angle beta _k of the illumination optical axis with respect to the light source position P _k of greater than angle beta ₀₀ is gradually decreases as k increases, the angle beta _{n =} 0 when P _k becomes P _n. Further, in other words, the optical axis of the P _k of the light source located in the angle beta ₀₀ or more will be directed to the uppermost end of the image capturing target area (Ai) to P _n.
The position _P n _{+ 1, P} n + 2, _..., it is difficult to control the orientation of the position and the illumination optical axis of the virtual source in the _{P 2n + 1,} the position _{P 0,} P 1, ... from disposed _{P n} source In order to irradiate the irradiation target surface with much of the emitted light, the mirror surface of the side mirror (plane mirror) is brought as close as possible to the light source at the position _Pn (the side mirror as the plane mirror contacts the light source at the position _Pn ). Until the side mirror is close to the light source at position _Pn ).

Incidentally, the side mirror PM2 constituting the side mirror pair provided on the outside of the light source position P _n, also provided in the region of the upper half with respect to the center line of the image capturing target area (Ai), the light source position P _n The side mirrors provided on the outside are arranged in parallel to each other. For this reason, an infinite number of imaginary light sources, which are mirror images of the imaginary light source, are generated by the pair of side mirrors. Among these, the imaginary light source generated by two or more reflections by the side mirror is considerably from the illumination target area (Ai) It occurs at a distant position. For this reason, the contribution rate by the mirror image of the imaginary light source to the illuminance distribution in the imaging target area (Ai) is extremely small and can be ignored.

  Next, the relative illuminance I (Mm) at an arbitrary point Mm in the imaging target area (Ai) illuminated by a plurality of light sources is determined. When the angle between the vertical line with respect to the illumination target area (imaging target area) (Ai) and the radiation vector of the light emitted from the light source toward the point Mm is α, the distance from the light source to the illumination target area (Ai) is Since it is L0, the distance from a certain light source to the point Mm is L0 / cos α. Assuming that the light flux emitted from the light source does not diverge in the sub-scanning direction (Sy), the light at the point Mm in the illumination target area (Ai) illuminated by the light emitted from each light source. The intensity is inversely proportional to the distance L0 / cosα from each light source to the point Mm. Further, the degree of reduction of the luminous flux due to the inclination of the surface at the same point Mm is cos α.

On the other hand, as shown in FIG. 24B, the intensity of light emitted from the light source in the direction of the radiation vector that forms an angle α with the vertical line with respect to the illumination target region (imaging target region) (Ai) is emitted from the light source. It depends on the distribution (envelope) of the radiation vector of light. Although the radiation vector distribution (envelope) of a light source such as an actual LED has a complicated shape, it is approximated by a circle or an ellipse for convenience of calculation. For example, as shown in (1) of FIG. 24, when the envelope of the radiation vector of the light emitted from the light source can be approximated to a circle, the direction of the radiation vector forms an angle α with respect to the illumination optical axis of the light source. The intensity of light emitted from the light source is reduced by cos α. If the envelope of the radiation vector of the light emitted from the light source can be approximated to an ellipse, the light source is emitted in the direction of the radiation vector that forms an angle α with the vertical line with respect to the illumination target area (imaging target area) (Ai). The degree of decrease in the intensity of light is approximated by cos ² α as shown in (2) of FIG. 24, cos ⁴ α as shown in (3) of FIG. 24, etc., depending on the shape of the envelope of the radiation vector. Is possible.

  Therefore, the relative illuminance I (Mm) at an arbitrary point Mm in the illumination target area (Ai) illuminated by a plurality of light sources is:

Represented by Here, A _k is a relative value of the total amount of light emitted from the k th light source, and α _k is the radiation vector of the k th light source toward the point Mm with respect to the vertical line of the illumination target area (Ai). Is an angle. Further, a is a coefficient that approximates the envelope of the radiation vector of the light source. For example, as shown in (1) of FIG. 24B, when the envelope of the radiation vector of the light source is close to a circle, a = 1, and when the envelope of the radiation vector of the light source is close to an ellipse For example, a> 1, and as shown in (2) and (3) of FIG. 24B, depending on the shape of the envelope of the radiation vector of the light source, for example, a = 2 and a = 3 is there. If the envelope of the radiation vector of the light source is flat, it can be approximated to a <1.

In particular, in the sixteenth embodiment of the present invention, the radiation vector of the light source emitted from the light source arranged at the position P _k and reaching the point Mm of the illumination target area (Ai) is the illumination target area (Ai). The angle of the straight line connecting the position P _k and the point Mm with respect to the vertical line is α _k , but the illumination optical axis of the light source arranged at the position P _k is only β _k with respect to the vertical line of the illumination target area (Ai). Since it is inclined, it is the light of the radiation vector that makes an angle α _k -β _k with respect to the illumination optical axis of the light source arranged at the position P _k .

In this way, it is possible to calculate the illuminance distribution over the entire illumination target area (Ai) illuminated by the entirety of the light source arranged in the lower half from the center line (CL) of the illumination target area (Ai). Moreover, if the obtained illuminance distribution is inverted symmetrically with respect to the center line (CL), the illumination target illuminated by the entire light source arranged in the upper half from the center line (CL) of the illumination target area (Ai) An illuminance distribution over the entire area (Ai) can be obtained. And the illuminance distribution over the whole illumination object area | region (Ai) illuminated by the whole light source arrange | positioned from the center line (CL) of illumination object area | region (Ai), and the center line (Ai) of the illumination object area | region (Ai) CL) and the illuminance distribution over the entire illumination target area (Ai) illuminated by the entirety of the light source arranged in the upper half, the illuminance distribution over the entire illumination target area (Ai) illuminated by all the light sources (However, in this calculation, the luminous flux emitted from the light source placed on P ₀ is used both when calculating the lower half from the center line (CL) and when calculating the upper half. The relative intensity A ₀ of the light source needs to be calculated as ½ of the relative intensity of the light source placed at other positions).

Therefore, the relative illuminance obtained with such a model is
W: Ld = 1: 1.5;
L00 = 2 × L0;
N = 12; and a = 2
Under the conditions, the calculation is performed over the entire illumination target area (Ai).

  FIG. 38 is a diagram showing simulation results for the difference between the relative illuminance and the target illuminance distribution in the sixteenth actual example of the present invention.

  About the illuminating device having the configuration shown in the twenty-first embodiment of the present invention, the illuminance distribution over the entire imaging target area (Ai) illuminated by a plurality of light sources in the same manner as in the twelfth embodiment of the present invention Asked. As a result, a graph similar to that in FIG. 25 could be obtained. FIG. 38 shows only an enlarged view of the difference between the illuminance distribution over the entire imaging target area (Ai) illuminated by a plurality of light sources and the target illuminance distribution. FIG. 38 shows the difference between the obtained illuminance distribution and the target illuminance distribution at any position of the imaging target area (Ai), and the illuminance at the periphery of the imaging target area (Ai) is the imaging target area (Ai). It is displayed so as to be larger than the illuminance at the center of the. In the graph of FIG. 38, the illuminance at the extreme end of the imaging target area (Ai) and the central part of the imaging target area (Ai) almost coincide with each other, and the maximum value of the difference shown in the graph of FIG. It is a little over + 8% at a position about 15% inside from the extreme end in the imaging target area (Ai). However, when the imaging target area (Ai) is uniformly illuminated as in the prior art, the ratio of the amount of light discarded at the center of the imaging target area (Ai) is 23%, and thus the imaging target area (Ai) Compared with the case of uniformly illuminating the light, the utilization efficiency of the light emitted from the light source can be greatly improved. Also, if the difference is such a level, even if the gain of the electrical signal after the light quantity is converted into an electrical signal by the one-dimensional CCD is changed and the difference is corrected, the rate of change of the gain is small and the influence of noise is reduced. There is little to receive.

Next, by adjusting the angle of the illumination optical axis of the light emitted from the plurality of light sources, the illuminance distribution of the light that illuminates the imaging region (Ai) is matched with the 1 / cos ⁴ θ characteristic. Demonstrate the concept.

FIG. 39 shows an illuminating device that matches the illuminance distribution of the light that illuminates the imaging region (Ai) with the 1 / cos ⁴ θ characteristic by adjusting the angle of the illumination optical axis of light emitted from a plurality of light sources. It is a conceptual diagram for implement | achieving. FIG. 39 (a) is a top view thereof, and FIG. 39 (b) is a front view thereof.

  In the illuminating device shown in FIG. 39, several items for making it easier to obtain a target illuminance distribution than the configuration of the illuminating device shown in FIG.

  In the diagram shown in FIG. 39, the light source LED and the convex lens form a virtual light source as shown in FIG. Further, as means for inclining the illumination optical axis of the light source with respect to the center line of the illumination target area (imaging area) (Ai), just as shown in FIG. 34, immediately after the illumination lens (3) of the convex cylinder lens. Can be used. In FIG. 37, the intervals between the plurality of light sources are equal, but also in the illumination device shown in FIG. 39, the intervals between the plurality of light sources themselves are equal. However, the position of the virtual light source is displaced from the illumination optical axis of the light source while the illumination optical axis of the optical axis is inclined. Regarding the displacement amount of the position of the virtual light source with respect to the illumination optical axis of the light source, the center line (center line: CL) of the imaging area (Ai), a certain point on the center line of the imaging area (Ai), and the edge of the imaging area (Ai) The interval between the virtual light sources included in the region between the straight lines connecting the portions (edge line: EL) increases as the position of the virtual light source is closer to the end. On the other hand, the interval between the virtual light sources included in the region outside the edge line of the imaging region (Ai) becomes smaller as the position of the virtual light source is closer to the end. Therefore, in order to obtain the same lighting device as the lighting device shown in FIG. 37 that is simulated, it is necessary to displace the position of the light source in correspondence with the displacement of the position of the virtual light source. The displacement of the position of the virtual light source is not a big problem.

Further, the radiation characteristic of the illumination lens (3) included in the region inside the edge line EL is a = 2, that is, cos ² α, and the illumination lens (3) included in the region outside the edge line EL. The radiation characteristic is a = 4, that is, cos ⁴ α. The radiation characteristic of the illumination lens (3) inside the edge line EL is made relatively divergent so that the illuminance at the central portion of the imaging region (Ai) is relatively reduced, and the illumination lens ( The radiation characteristic of 3) is made relatively convergent, and the illuminance in the peripheral portion of the imaging area (Ai) is relatively increased. As a result, the size of the difference peak shown in FIG. 38 can be reduced. Furthermore, by combining the configuration of this embodiment with the configuration of this embodiment, such as designing the radiation characteristic of the illumination lens (3) near the center of the imaging area (Ai) to be a = 1, that is, cos α, FIG. The magnitude of the difference peak shown can be further reduced.

  Although typical configurations have been described as the 11th to 16th embodiments of the present invention, it is possible to combine, modify, and partially change the configurations described in the 11th to 16th embodiments of the present invention. Is possible. For example, depending on the convenience of manufacturing the lighting device, a plurality of LEDs can be integrated into a single unit, a cylinder lens array and / or a prism array can be used, the optical axis of the cylinder lens can be shifted, and the unit cost of parts can be further reduced. It is also possible to do. Moreover, also about the example which showed the condensing lens as a hood lens, a condensing lens can also be provided independently of LED.

  Further, as means for forming a virtual light source with respect to the light source, the light beam from the light emitting source LED is made substantially parallel light, and then the convex cylinder lens is positioned at the focal position of the convex cylinder lens only in the main scanning direction (Sx) We have described the formation of a virtual light source by focusing once. However, even if the convex cylinder lens is replaced with a concave cylinder lens, a virtual light source can be similarly formed from the light source.

  FIG. 40 is a diagram for explaining the formation of a virtual light source VLS from a light source using a concave cylinder lens. FIG. 40A is a top view of an optical system using a concave cylinder lens, and FIG. 40B is a front view of the optical system using a concave cylinder lens. As shown in FIG. 49, the light beam emitted from the light-emitting light source LED can be diverged only in the main scanning direction (Sx) by the concave cylinder lens after making the light beam approximately parallel using a convex lens. At this time, the position of the virtual light source with respect to the light source is formed at the focal point of the concave cylinder lens (focal length f1) as shown in FIG. That is, by using the concave cylinder lens, the virtual light source VLS can be positioned closer to the light source than the concave cylinder lens (when a convex cylinder lens is used, closer to the imaging region (Ai) side than the concave cylinder lens). A virtual light source is formed). For this reason, it becomes possible to further reduce the size of the illumination device by appropriately selecting the focal length f1 of the concave cylinder lens.

  Further, since it is desirable to use a light source that emits light in as small a volume as possible, an LED (light emitting diode) is suitable. Not only the single color light such as red (R), green (G), blue (B), etc. as a single light emitter, but also a plurality of them integrated into white light or white LED In addition, a device such as a blue LED or a violet LED that emits a luminous flux to a phosphor to obtain white light can be applied to the apparatus of the present invention. In addition, a neon tube, a discharge lamp such as a small high-pressure mercury lamp, a small bulb-shaped filament bulb, and the like are also applicable.

  Finally, main optical component forms that can be used in the embodiments and examples of the present invention will be described.

  41 and 42 are diagrams illustrating optical components that can be used in the embodiments and examples of the present invention.

  FIG. 41A shows an example of a first cylinder lens array. The first cylinder lens array as shown in FIG. 41 (a) is composed of a plurality of convex cylinder lenses arranged adjacent to each other, and is used as an illumination lens in the embodiments and examples of the present invention. obtain.

  FIG. 41B is a diagram illustrating an example of the second cylinder lens array. The first cylinder lens array as shown in FIG. 41 (b) is composed of a plurality of concave cylinder lenses arranged adjacent to each other, and is used as an illumination lens in the embodiments and examples of the present invention. obtain.

  FIG. 41C is a diagram illustrating an example of the first cylinder lens. The first cylinder lens as shown in FIG. 41C has a plano-convex cross section, and can be used as a focusing lens in the embodiments and examples of the present invention.

  FIG. 41D is a diagram illustrating an example of the second cylinder lens. The second cylinder lens as shown in FIG. 41 (d) has a biconvex cross section, and can be used as a focusing lens in the embodiments and examples of the present invention.

  FIG. 41E is a diagram illustrating an example of a parabolic mirror or an ellipsoidal mirror. A parabolic mirror or ellipsoidal mirror as shown in FIG. 41 (e) has a parabolic or elliptical cross section in one direction, and a parallel plane in a direction perpendicular to that direction. It is a mirror which has the cross section. A parabolic mirror or an ellipsoidal mirror as shown in FIG. 41 (e) can be used as a focusing mirror in the embodiments and examples of the present invention. Since the shape of the parabolic mirror or ellipsoidal mirror as shown in FIG. 41 (e) is easily formed using a bright aluminum thin plate, the parabolic mirror or ellipse as shown in FIG. The cost for manufacturing the surface mirror can be reduced.

  FIG. 41F is a diagram illustrating an example of a plane mirror. A plane mirror as shown in FIG. 41 (f) can be used as a turning mirror and a folding mirror in the embodiments and examples of the present invention. Here, when a plane mirror as shown in FIG. 41 (f) is used as a turning mirror, in order to reflect light having image information, the plane mirror as shown in FIG. A plane mirror with one surface as a mirror surface is preferable. When a plane mirror as shown in FIG. 41 (f) is used as a folding mirror, the plane mirror as shown in FIG. 41 (f) may be a plane mirror manufactured using a bright aluminum plate.

  Fig.42 (a) is a figure which shows a convex cylinder lens. A convex cylinder lens as shown in FIG. 42A can be used as an illumination lens in the embodiments and examples of the present invention.

  FIG. 42B shows a concave cylinder lens. A concave cylinder lens as shown in FIG. 42A can be used as an illumination lens in the embodiments and examples of the present invention.

  FIG. 42C shows a prism. In the embodiments and examples of the present invention, the prism as shown in FIG. 42C can be used as an optical element that bends (deflects) the illumination optical axis.

  Although the embodiments and examples of the present invention have been specifically described above, the present invention is not limited to these embodiments and examples, and these embodiments and examples of the present invention are not limited thereto. Can be changed or modified without departing from the spirit and scope of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... LED (or LED chip), 2a ... Rotary parabolic mirror, 2b ... Rotating ellipsoidal mirror, 2c ... Convex lens, 2d ... Parabolic mirror, 3 ... Illumination lens, 4a ... Converging lens, 4b, 4b1, 4b2 ... Focusing mirror, 5, 5a, 5b ... Side mirror, 6, 6a, 6b ... Folding mirror, 7 ... Prism, 8 ... Concave cylinder, 10 ... Illumination unit, 11 ... First traveling body, 11a ... Running body, 12 ... Deflection mirror, 13 ... contact glass, 14 ... imaging lens, 15 ... one-dimensional imaging device, 16 ... reading unit, 17a, 17b, 17c ... folding mirror, 18 ... color filter, 21 ... electrode, 22 ... lead wire, DESCRIPTION OF SYMBOLS 23 ... Transparent resin, 24 ... Hood lens, 25 ... Base, 31 ... Photoconductor, 32 ... Paper feed roller, 33 ... Sheet original, Sx ... Main scanning direction, Sy ... Sub scanning direction, AxI ... Illumination optical axis, xR ... reading the optical axis, Ai ... imaging area, the illumination area, the illumination target region, Di ... illuminance distribution, Vl ... longitudinal, Vs ... lateral direction, VLS ... virtual source, the virtual light source.

JP 2005-204272 A JP 2005-242263 A

Claims (4)

In a document illumination device that illuminates a document by superimposing light emitted from a plurality of light sources arranged in a first direction on the document surface,
A lens array provided corresponding to each of a plurality of light beams emitted from each of the plurality of light sources, and having a positive refractive power in the first direction and perpendicular to the first direction. A first lens having no refractive power in two directions, a focal length is F, and the first lens and the document surface are disposed at a position separated from the document surface by a focal length F; A second lens having no refractive power in the first direction and having a positive refractive power in the second direction, and each of the plurality of light sources emits light for each color of red, green, and blue A set of light emitting light sources that are covered with a hood lens composed of a convex lens with a convex surface facing the document surface on which the document is placed;
The focal length of the hood lens is f0, and the distance a from the red, green, and blue light emitting sources to the principal point to the hood lens is arranged to be equal to the focal length f0. The optical axis of the light beam emitted from the green light source among the red, green, and blue light sources is configured to coincide with the optical axis of the hood lens ,
The plurality of light sources arranged in the first direction are such that the central portion in the first direction is closest to the original surface, and further away from the original surface with the light source from the central portion toward the peripheral portion. Arranged in the
The focal lengths f0 of the hood lenses provided in the individual light sources are all the same, and each lens focal length f1 in the lens array that is the first lens changes according to the arrangement in the first direction, The relationship between the focal length f1 of the first lens corresponding to the light source at the center in the first direction and the focal length f0 of the hood lens is:
The document illumination device according to claim 1, wherein f0> f1, f0 = f1 as it goes from the center to the periphery, and then f0 <f1 . In a document illumination device that illuminates a document by superimposing light emitted from a plurality of light sources arranged in a first direction on the document surface,
A lens array provided corresponding to each of a plurality of light beams emitted from each of the plurality of light sources, and having a positive refractive power in the first direction and perpendicular to the first direction. A first lens having no refractive power in two directions, a focal length is F, and the first lens and the document surface are disposed at a position separated from the document surface by a focal length F; A second lens having no refractive power in the first direction and having a positive refractive power in the second direction, and each of the plurality of light sources emits light for each color of red, green, and blue A set of light emitting light sources that are covered with a hood lens composed of a convex lens with a convex surface facing the document surface on which the document is placed;
The focal length of the hood lens is f0, and the distance a from the red, green, and blue light emitting sources to the principal point to the hood lens is arranged to be equal to the focal length f0. The optical axis of the light beam emitted from the green light source among the red, green, and blue light sources is configured to coincide with the optical axis of the hood lens,
The plurality of light sources arranged in the first direction are all arranged at an equal distance from the document surface, and the focal lengths f0 of the hood lenses provided in the individual light sources are all the same. The focal length f1 of each lens in the lens array which is the first lens changes according to the arrangement in the first direction, and the first lens corresponding to the light source at the center in the first direction The focal length f1 of the hood lens and the focal length f0 of the hood lens are f0> f1, passing through f0 = f1 from the center to the periphery, and then f0 <f1, For the plurality of light sources excluding the light source arranged in the center in the direction and the light sources arranged at both ends in the first direction, the optical axis of each light source is arranged in the center in the first direction. An original illuminating apparatus , wherein a prism is disposed immediately after the first lens so as to be inclined outward with respect to the optical axis of the light source . Side mirrors are arranged on both side surfaces in the first direction of the first lens, and the side mirrors are arranged on both sides in the first direction of the second lens from both side surfaces in the first direction of the hood lens. The document illumination device according to claim 1 , wherein the document illumination device is provided over a surface. An image reading apparatus that illuminates a document with the document illumination device according to any one of claims 1 to 3 ,
An image reading apparatus comprising: an image forming optical system that forms an image of light scattered or reflected from the illuminated original; and an image pickup device that picks up an image formed by the image forming optical system. .

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