JP2008172302A - Light source unit, read unit, image reader, and image-forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image-forming device that is advantageous to the deterioration of image quality when reading an original, dispenses with the arrangement of an optical path for guiding illumination light in a read optical path, saves the space of a reflection material, and reduces costs. <P>SOLUTION: Luminous flux emitted from an LED 6 is set to be nearly parallel luminous flux by a rotational parabolic mirror for output. The luminous flux passes through a condensing lens 7 and an illumination lens 8 nearly in parallel; a portion outside the center of an integration lens 9 is used; and an LED 6 that is a light source, the condensing lens 7, the illumination lens 8, and the integration lens 9 are placed next to an image-forming lens 3 in one unit. The illumination light L emitted from the lighting system 11 is reflected by a mirror 12 for lighting a read region on contact glass 5 uniformly. The reflected light is reflected on a first read mirror 13 and second and third mirrors 14, 15 for forming an image on a CCD 17 by a lens 16 to perform one-dimensional read. The lighting system 11 is arranged outside a read optical path. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an illumination device for a reduction optical system image reading device equipped with a solid-state imaging device and an imaging lens, an illumination device, a film scanner equipped with the same, a book manuscript, etc. The present invention relates to a scanner, particularly a configuration of an upper surface of a document table, and the like, and a light source unit, a reading unit, and an image reading apparatus and an image forming apparatus including the light source unit.

  For these various apparatuses, various improved technologies for the light source unit have been proposed. For example, in Patent Document 1, the reflector is excluded from the reflector and the light source, and the light source is fixed and arranged far from the document surface. Thus, a technique is disclosed in which the main objective is to reduce the flare phenomenon, and further, a light source is provided at a site different from the traveling body to reduce the cost by eliminating the reflector.

  Further, in Patent Document 2, although it is limited to the working mirror system, a dedicated mirror installed near the document surface is provided while light sources are arranged on the upper and lower sides of the image sensor and the imaging optical system of the image sensor is shared. A technique for using it to illuminate a reading position is disclosed.

  Further, Patent Document 3 discloses a technique in which a half mirror is used to read and illuminate at the same position by sharing an imaging optical system between an imaging element and a light source.

  Further, Patent Document 4 proposes an image reading apparatus that can prevent a reduction in the amount of light on the image reading surface without using a side reflector.

JP 2000-253213 A JP-A-10-190990 Japanese Patent Laid-Open No. 9-51405 JP 2000-250146 A

  The technology disclosed in Patent Document 1 eliminates the reflector and realizes a configuration in which the light source is separated from the side of the document surface, thereby achieving low cost, high image quality reading and miniaturization by reducing flare phenomenon. However, the following problems occur or remain.

Regarding the techniques of Patent Documents 1, 2, and 4,
-Since the reading optical axis and the illumination optical axis are substantially the same and perpendicular to the original, the reading value changes depending on the gloss of the original (at least the angle with the normal is not specified),
When the first and second carriages scan, each mirror position changes sequentially when reading a two-dimensional document image, so that the position where the illumination light reaches the document surface varies as the document is scanned. Therefore, high-quality image reading is not possible, such as brightness fluctuations in the read image,
There is a problem.

Regarding the technology of Patent Document 3,
・ The cost is increased by using a half mirror, and the illumination light is halved at the time of emission and incidence by the half mirror, respectively. Finally, the effective illumination light quantity can be obtained only ¼ times, resulting in a large energy loss. In addition, the illumination light emitted from the half mirror in the lens direction is inevitably reflected on the lens surface and incident on the image sensor, and the flare light is always generated, so that a sufficient SN ratio in image reading is obtained. Hard to get,
There is a problem.

  At the product level, a cold-cathode tube is illuminated with a width, and the image of the reading area developed in the depth direction of the paper is reduced and imaged on a one-dimensional image sensor (for example, CCD) by an imaging lens. A method is known in which one-dimensional image information is obtained, the whole is mounted on a traveling body, and a two-dimensional image is obtained by traveling in a direction perpendicular to the depth direction of the paper while sequentially acquiring one-dimensional images. ing. In such an apparatus, the traveling body is often made compact by bending a plurality of reading optical paths with a plurality of mirrors. In this illumination method, the aperture is narrowed so that the light beam is effectively applied to the reading area, or the leaked light beam is bent by a reflecting mirror, but the light beam inevitably diverges and is effectively irradiated to the reading area. The actual light flux is 1% or less of the light flux emitted from the light source.

The above-mentioned conventional patents and products are basically based on the following ideas.
That is, a (micro) line light source is installed between the imaging lens and the image sensor, and the imaging lens forms an image of the light on the document surface on the image sensor and simultaneously transmits the light from the line light source to the document surface. It also has a function of condensing light on the image sensor reading area.

This configuration has the following advantages.
1. Since the illumination light and the reading light are completely the same optical system, even if the optical system (such as a mirror) up to the document surface fluctuates, the positional relationship between the two does not collapse and stable image reading can be performed.
2. Since most of the illumination light can be collected in the reading area, unnecessary light is not generated, and as a result, energy saving can be achieved.
3. Since there is no need to install a lamp or reflector near the document surface, the height of the scanner body can be reduced.

However, there are also the following disadvantages.
1. Since a (micro) line light source (lamp) is installed between the element and the imaging lens, a part of the field of view of the image sensor is blocked by the lamp, and image quality such as MTF deteriorates.
2. A part of the light emitted from the light source returns directly or indirectly to the image sensor, and the quality of the read image is deteriorated as flare light.
3. It cannot be said that the utilization efficiency of the amount of light emitted from the light source has been sufficiently increased.

  Various techniques have been proposed as methods for eliminating such drawbacks. For example, since the illumination light is the same optical system as the reading light, the illumination light is emitted when dust or dirt adheres during use as a device. There has been proposed a technique in which the dust is diffusely reflected by the dust and directly enters the reading lens as flare light and is superimposed on the image light on the original surface on the CCD.

  However, in these already proposed technologies, only the reading method of the operating mirror method is applied, or the superimposing illumination device is arranged in the reading optical path although it is an optical module configuration, and image quality degradation ( For example, there is a problem that it is disadvantageous to image noise in flare light.

  Therefore, the present invention is advantageous for image quality degradation in reading a document by mounting the reading system and the illumination system on the same traveling body, and illuminating illumination from the outside of the optical path of the CCD-document surface, and also leading the illumination light. It is not necessary to arrange the optical path in the reading optical path, and it is possible to save space and reduce the cost of the reflecting material. Further, it is possible to secure the distance to various heat sources and to reduce the thermal stress of the light source etc. An object is to provide an image forming apparatus.

  A light source unit according to claim 1 of the present invention forms reflected light from an original illuminated by a light source on an image sensor with an imaging lens, reads an image of the original one-dimensionally, and scans the image. In a light source unit used in an image reading apparatus for reading a two-dimensional image, the light source unit includes at least a plurality of illumination lenses, and the illumination lenses divide a light beam emitted from the light source into a plurality of light beams, and the divided light beams are formed on one surface. It is characterized by being superposed on top.

  A reading unit according to a second aspect of the present invention includes the light source unit according to the first aspect and an illuminating device, and the imaging device, an imaging lens, a reflecting mirror, and the like and the illuminating device are mounted on the same traveling body, In a reading unit comprising a reading component capable of reading a two-dimensional image by running a traveling body in the sub-scanning direction, the illumination device and the original illumination optical path are arranged outside the reading unit optical path.

  According to a third aspect of the present invention, in the reading unit according to the second aspect, a part of the illumination light from the illuminating device disposed outside the optical path of the reading unit is transferred from the original surface to the first reflecting mirror. It is characterized by irradiating the surface of the document across

  According to a fourth aspect of the present invention, in the reading unit according to the second or third aspect, the illumination light from the illuminating device is set to a reading line direction which is a main scanning direction.

  According to a fifth aspect of the present invention, in the reading unit of the fourth aspect, the illumination device that performs the illumination to be superimposed is configured as at least one group.

  According to a sixth aspect of the present invention, in the reading unit of the fifth aspect, the number of light sources in each group is different.

  According to a seventh aspect of the present invention, in the reading unit according to the fifth or sixth aspect, the arrangement pitch in units of groups is made smaller than the distance from the light source to the original reading surface.

  According to an eighth aspect of the present invention, in the reading unit according to any one of the second to seventh aspects, the illumination device is provided on an upper lid of the reading unit case.

  According to a ninth aspect of the present invention, in the reading unit of the ninth aspect, an engaging portion is provided for attaching the illumination device to the upper lid.

  According to a tenth aspect of the present invention, in the reading unit of the ninth aspect, an engaging portion for attaching the illumination device is provided in a case portion other than the upper lid.

  According to an eleventh aspect, in the reading unit according to the ninth or tenth aspect, the illumination device is provided so as to be sandwiched between the upper lid and the other case portion.

  According to a twelfth aspect of the present invention, in the reading unit according to any one of the eighth to eleventh aspects, the upper lid and the case are formed of a member that does not transmit light.

  According to a thirteenth aspect of the present invention, in the reading unit of the twelfth aspect, the upper lid and the case are made of a moldable resin material.

  A document reading apparatus according to a fourteenth aspect of the present invention includes the reading unit according to any one of the second to thirteenth aspects.

  An image forming apparatus according to a fifteenth aspect of the present invention includes the reading unit according to any one of the second to thirteenth aspects or the document reading apparatus according to the fourteenth aspect.

  The present invention is advantageous for image quality deterioration in reading a document, can save space and reduce costs, can secure a distance from a heat source in the apparatus, and can reduce thermal stress. There is an effect of becoming.

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

  FIG. 1 is a schematic cross-sectional view showing an outline of an image forming apparatus provided with an image reading apparatus that can use a light source unit and a reading unit according to the present invention. In this figure, 100 is an image forming unit, 200 is a paper feeding unit, 300 is an image reading unit comprising the image reading apparatus of the present invention, and 400 is a document feeding unit.

  In the document feeder 400, when the document is fed automatically or manually directly above the image reading unit 300, the image reading unit 300 performs sub-scanning by driving the first carriage and the second carriage at a predetermined speed as will be described later. The document image is taken into a sensor (not shown) by the lens unit. The image forming unit 100 forms an image by color-coding a plurality of photoconductors based on the color-separated information of the read image, and superimposes and transfers the image onto a transfer sheet sent from the paper feeding unit 200. Make a full color hard copy.

  The concept of efficiently illuminating the illumination target surface while suppressing uneven illuminance in the main scanning direction will be described with reference to FIG. In the figure, 1 is a first light source unit, 2 is a second light source unit (only the center line of the arrangement position is shown, and although not shown, it has the same configuration as the first light source unit 1), 3 is a plurality of lenses An imaging lens, which is a lens group consisting of 4, 4 is an image sensor such as a CCD, 5 is a contact glass, and D is a document.

  Both the light source units 1 and 2 use LEDs 6 arranged in a straight line. Although not shown in detail, the individual LEDs 6 are encapsulated with a transparent resin, and a rotary parabolic mirror is formed on the rear side thereof so that the light beam emitted from the LEDs 6 is output as almost parallel light. It is. The focal length as an optical system made of this transparent resin is the distance from the rotary parabolic mirror to the position of the LED 6. That is, each rotary paraboloid mirror has an LED 6 at its focal position, and reflects the light beam emitted from the LED 6 into parallel light.

  The condensing lens 7 arranged on the front side of the LED 6 divides the light beam from the LED 6 as the light source in the main scanning direction, and the light beam cut out into individual cylinders (lenses) of the illumination lens 8 located on the front side. It is the lens which condenses in order to transmit all. As this cylinder (lens), a cylinder (lens) array having a shape as shown in FIG. 3A and a cylinder (lens) as shown in FIG. ) May be arranged).

  Positioned on the front side of the illumination lens 8 is an integrated lens 9 that is divided by the condenser lens 7 and the illumination lens 8, and a lens for superimposing the irradiated light beam on the illumination target surface (contact glass 5 in the example in the figure). Therefore, it is a normal lens arranged symmetrically with respect to the main optical axis. The optical axis (referred to as the secondary optical axis) of the light beam divided by the condenser lens 7 and the illumination lens 8 is aligned with the center (main optical axis) of the illumination target surface, and the divided light beam can be superimposed on the illumination target surface. .

  With this setting, an image of the size of the individual cylinder of the condenser lens 7 is projected to the size on the illumination target surface, and all the light beams that have passed through the width of the individual cylinders of the cylinder array reach the illumination target surface ( Illumination by the individual light fluxes from the cylinders causes uneven illuminance, but as a result of superimposing the whole, it becomes flat.

Next, the illumination concept in the direction perpendicular to the main scanning direction (sub-scanning direction) will be described with reference to FIG.
As described, the light beam emitted from the LED 6 encapsulated with the transparent resin is converted into a substantially parallel light beam by the rotary parabolic mirror 10 disposed at the rear end, and is output. Since the condensing lens 7 and the illumination lens 8 behave in the same manner as a parallel plate at this point of view, the light beam that has become substantially parallel first passes through the light as it is with little influence.

  As shown in FIG. 2, the integrated lens 9 uses a portion removed from the center of the lens. This is because the LED 6, the condenser lens 7, the illumination lens 8, and the integrated lens 9 that are light sources can be put together as a single unit and placed beside the imaging lens 3. Can be treated as a device.

  FIG. 5 is a conceptual diagram showing the configuration of the reading unit. The illumination light L emitted from the illuminating device 11 as described above is reflected by the mirror 12 and uniformly illuminates the reading area on the contact glass 5. For example, if an original is placed in the reading area, reflected light along the reading optical axis R is generated by the original surface, so that the reflected light is reflected by the first reading mirror 13 and then the second and third mirrors. 14 and 15 are reflected twice, and the image is formed on the CCD 17 by the lens 16 to perform one-dimensional reading. At this time, the illumination device 11 is disposed outside the reading optical path.

  That is, the reading system and the illumination system are mounted and mounted on the same traveling body, and the illumination light is irradiated from outside the optical path of the CCD-document surface. That is, reflected light from a document illuminated by a light source is imaged on an image pickup element by an imaging lens, used for an image reading apparatus that reads a two-dimensional image by reading the document image one-dimensionally and scanning it. An illumination device that has at least a plurality of illumination lenses, divides a light beam emitted from a light source by these illumination lenses into a plurality of components, and superimposes the plurality of divided light beams on a document surface; A configuration in which an imaging lens, a reflection mirror, and the like and an illuminating device are mounted on the same traveling body, and a scanning component (scanner module) capable of scanning the traveling body in the sub-scanning direction and reading a two-dimensional image is used as a scanning unit. In this example, the illuminating device and the original illumination optical path are arranged outside the optical path of the reading unit. Advantageously configured to image noise in the rare light. Further, since it is not necessary to arrange an optical path for guiding the illumination light in the reading optical path, it is possible to save space for the reflecting material and reduce the cost. Furthermore, by arranging a light source on the upper surface side inside the scanner module, it is possible to secure a distance from a heat source existing in the unit such as a substrate of an image sensor such as a CCD, and both the light source and the substrate of the image sensor are subjected to thermal stress. Alleviated.

  FIG. 6 is a conceptual diagram showing the configuration of a reading unit for double-side illumination. The lower half of the illumination light L is irradiated from one direction to the original surface (not shown) on the contact glass 5 by the mirror 12a, and from the other side by the mirror 12b. Illumination light is irradiated from both sides.

  That is, the illumination device and the original illumination optical path are arranged outside the reading unit optical path, and a part of the illumination amount is irradiated from the original surface to the original surface with the reading unit optical path between the first reflecting mirror from the original surface, This is advantageous for image quality deterioration during document reading, for example, image noise in flare light, and the influence of reflection flare that is influenced by the reflection characteristics of the document is reduced. When the reading unit optical path is sandwiched between the first reflecting mirror from the document surface and the document surface is irradiated, the step of the document, the shadow of the floating portion of the binding portion of the book document, and the shadow of the edge of the superimposed document, for example, occur. It becomes hard to be reflected.

  FIG. 7 is a conceptual diagram illustrating a configuration example of a two-part illumination device. The lighting device 11 shown in FIG. 2 is used as a light source unit as a group, and a plurality of light source units are arranged in the main scanning direction. In FIG. 7, two groups, that is, two light source units 11a and 11b are arranged to irradiate the reading area on the contact glass 5. At this time, the two illumination lights La and Lb from the two light source units 11a and 11b are irradiated with overlapping portions in the main scanning direction. That is, the light source units are arranged in units of groups, and the superimposed illumination is configured as at least one group, so that the amount of light on the document surface can be arbitrarily adjusted by the arrangement and arrangement of the groups, and the illumination ripple (illumination unevenness) is reduced. Can be suppressed.

  FIG. 8 is a conceptual diagram showing a configuration example of a three-divided uneven illumination device. In this example, a group divided into three (light source units 11a, 11b, and 11c) is used. With respect to the central light source unit 11c, light source units 11a and 11b are placed on both sides of the central light source unit 11c, and a group of three light source units in total is formed. The number of LEDs 6 of the light source unit 11c is smaller than that of the light source units 11a and 11b, and the illuminance on the original surface by the three illumination lights La, Lb and Lc is as shown in FIG. Has a dark illumination distribution. This eliminates the shortage of the peripheral light amount (according to the cos 4 power law of the reading lens 16).

  That is, the light source units are arranged in units of groups, and the superimposed illumination is configured as at least one group, so that the amount of light on the document surface can be arbitrarily adjusted by the arrangement and arrangement of the groups, and the illumination ripple (illumination unevenness) is reduced. Can be suppressed. Further, the superimposed illumination is configured as at least one group, the number of light sources in each group is different, and the superimposed illumination is configured as at least one group. The amount of light on the original surface can be adjusted arbitrarily, and illumination ripple can be suppressed.

  FIG. 10 is a conceptual diagram illustrating an example of the configuration of the small pitch group illumination. In this example, the three divided groups (light source units 11 a, 11 b, 11 c) are illuminated by being superimposed on the surface of the contact glass 5. The distance (pitch) between the three groups at this time is represented by [P], and the distance from the light source units 11a, 11b, and 11c to the document surface, that is, the surface of the contact glass 5 is represented by [S]. The light source units 11a, 11b, and 11c are arranged so as to satisfy the relationship.

  FIG. 11 shows a reading unit having the same configuration as FIG. 6, but the case 30 is divided into two parts, and the upper case is mounted on the lower case 32 as the upper cover 31, and the light source unit 11 is fixed to the upper cover 31. An example is shown. The upper lid 31 has a portion corresponding to the reading optical axis R as a window opening 31a for illumination and reading. Mounting the module including the light source on the top lid can contribute to the simplification of assembly man-hours.

  That is, the superimposed illumination is configured as at least one group, and each group arrangement pitch is set to be smaller than the distance from the light source to the document reading, so that each illumination group on the document surface and the light weight from each light source are on the document surface. Since it is equally close to the overlap, the illumination ripple can be suppressed even by arranging the group and the light source in relation to the number pitch to be divided and superimposed.

  FIG. 12 is a perspective view specifically showing the structure of FIG. A hole 33 and a hook 34 are respectively provided in the mating portion of the upper lid 31 of the reading unit and the lower case 32 forming the lower structure, and are configured to be fitted and engaged when assembling. As a result, assembly is simplified and the number of assembly steps can be reduced. Further, since screws are not used to fix the upper lid 31 and the lower case 32, which are structural bodies, the number of parts can be reduced and the cost can be reduced. Further, since the light source is arranged on the upper side inside the module, a distance from a heat source such as a CCD substrate can be secured, and thermal stress is reduced in both the light source and the substrate. Further, the placement accuracy of the illumination device is determined with high accuracy relative to the module placed with a CCD or the like.

  FIG. 13 is a conceptual cross-sectional view showing a structure in which the light source unit that is unitized as described above is sandwiched between the mating portions of the upper lid 31 and the lower case 32. Although not shown in the drawings, protrusions are provided on the periphery of the structure forming the light source unit 11 in each direction, and are fixed by being sandwiched between the mating portions of the upper cover 31 of the reading unit and the lower case 32 forming the lower structure. . Of course, other fixing structures may be used. Also in this example, the thermal stress is alleviated in both the light source and the CCD substrate.

  It should be noted that if the material constituting the reading unit is made of a material that does not transmit light and is made of a moldable resin material or the like, it is possible to perform molding processing with high productivity, and by providing projections, rib shapes, etc. This is also advantageous for image quality deterioration and excellent sealing performance.

  In addition, if the above-described apparatus and unit are employed in an image reading apparatus and an image forming apparatus, it is possible to read an image with high accuracy and to maintain input information for high-precision image formation with high accuracy. Become.

1 is a schematic cross-sectional view showing an outline of an image forming apparatus including an image reading apparatus that can use a light source unit and a reading unit according to the present invention. The figure which shows the concept of illuminating the illumination target surface efficiently while suppressing the illuminance unevenness in the main scanning direction Diagram showing various cylinders (lenses) The figure which shows the illumination concept of the direction (sub-scanning direction) at right angles to the main scanning direction Conceptual diagram showing the configuration of the reading unit Conceptual diagram showing the configuration of a reading unit with double-sided illumination Conceptual diagram showing a configuration example of a two-part illumination device Conceptual diagram showing a configuration example of a three-divided uneven illumination device The figure which shows the illumination distribution of the structural example of FIG. Conceptual diagram showing an example of the configuration of small pitch group illumination The figure which shows the structural example which divided the case of the reading unit into the top and bottom and made the upper case the upper lid FIG. 11 is a perspective view specifically showing the structure of FIG. A conceptual cross-sectional view showing a structure in which a unitized light source unit is sandwiched between upper and lower case joints

Explanation of symbols

1: First light source unit 2: Second light source unit 3: Imaging lens 4: Imaging element 5: Contact glass 6: LED
7: Condensing lens 8: Illumination lens 9: Integrated lens 10: Rotating parabolic mirror 11: Illumination devices 11a, 11b, 11c: Light source units 12, 12a, 12b: Mirror 13: First reading mirror 14: Second Mirror 15: Third mirror 16: Lens 17: CCD
30: Reading unit case 31: Upper lid 32: Lower case 31a: Window opening 33: Hole 34: Hook 100: Image forming unit 200: Paper feeding unit 300: Image reading unit 400: Document feeding unit D: Documents L, La , Lb, Lc: Illumination light P: Group interval (pitch)
R: Reading optical axis S: Distance from light source unit to document surface

Claims (15)

Reflected light from a document illuminated by a light source is imaged on an image sensor with an imaging lens, and is used in an image reading apparatus that reads a two-dimensional image by reading the image of the document one-dimensionally and scanning it. The light source unit includes at least a plurality of illumination lenses, and the illumination lens divides a light beam emitted from the light source into a plurality of light beams and superimposes the divided light beams on one surface. Light source unit. A light source unit according to claim 1 and an illuminating device are mounted. The imaging device, imaging lens, reflecting mirror, and the like and the illuminating device are mounted on the same traveling body, and the traveling body is traveled in the sub-scanning direction to perform two-dimensional. A reading unit comprising a reading component capable of reading the image of the reading unit, wherein the illumination device and the original illumination optical path are disposed outside the reading unit optical path. 3. The reading unit according to claim 2, wherein a part of the illumination light from the illuminating device arranged outside the reading unit optical path is irradiated on the document surface with the reading unit optical path between the document surface and the first reflecting mirror. A reading unit. 4. The reading unit according to claim 2, wherein the illumination light from the illumination device is in a reading line direction which is a main scanning direction. 5. The reading unit according to claim 4, wherein the illumination device that performs the superimposed illumination is configured as at least one group. 6. The reading unit according to claim 5, wherein the number of light sources in each group is different. 7. The reading unit according to claim 5, wherein an arrangement pitch in units of groups is made smaller than a distance from the light source to the original reading surface. The reading unit according to claim 2, wherein the illumination device is provided on an upper lid of the reading unit case. The reading unit according to claim 9, further comprising an engaging portion for attaching the illumination device to the upper lid. The reading unit according to claim 9, wherein an engagement portion for attaching the illumination device is provided in a case portion other than the upper lid. 11. The reading unit according to claim 9, wherein the illumination device is provided so as to be sandwiched between the upper lid and the other case portion. 12. The reading unit according to claim 8, wherein the upper lid and the case are formed of a member that does not transmit light. 13. The reading unit according to claim 12, wherein the upper lid and the case are made of a moldable resin material. An original reading apparatus comprising the reading unit according to claim 2. An image forming apparatus comprising the reading unit according to claim 2 or the document reading device according to claim 14.