JP2004349964A - Illuminator and image input apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact illuminator and an image input unit having the illuminator which uses only light containing visual components for the illumination, even if the light contains IR components, and also uses defect-correcting light containing IR components for the illumination. <P>SOLUTION: A light emitter having first light emitting elements for emitting light containing visual components and IR components, and second light emitting elements for emitting light containing IR components only. The first and the second light emitting elements are arranged in different rows on a board. The light emitter has an optical element having a first surface which transmits either of light containing visual components or light containing IR components and reflects the other, and a second surface which reflects the light transmitted through the first surface. The first and the second light emitting elements of the light emitter and the first and the second surfaces of the optical element are so disposed as to guide the light containing the visual components emitted from the first light emitting element and the light emitted from the second light emitting element out of the light reflected from the first surface and the light from the second surface to a common optical path. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an illumination device for illuminating a document, and an image input device provided with the illumination device.
[0002]
[Prior art]
Conventionally, there is an image input device that optically reads an image of a transparent original (film original). Some of such image input devices include a monochrome one-line sensor and switch point light sources of red (R), green (G), and blue (B) on the light source side. In addition to the RGB, some include an infrared (I) light source for performing defect correction (dust / dust damage correction). In such an image input device, there has been known an image input device in which the above-mentioned point light sources are arranged in a plurality of rows and an optical element for selectively reflecting and transmitting light from the point light sources is provided in order to reduce the size of the illumination device. (For example, see Patent Document 1).
[0003]
In the above-described image input device, light-emitting diodes (Light-Emitting Diodes, hereinafter referred to as “LEDs”) of each color exhibiting spectral characteristics as shown in FIG. 7A are used as light sources. As a red light source, a red LED having a peak near 660 nm is generally used. However, since this red LED has poor color reproducibility, it is required to use a red LED having better color reproducibility. A red LED having better color reproducibility is a red LED having a peak near 630 nm as shown in FIG. 7B.
[0004]
[Patent Document 1]
JP-A-10-322519 [0005]
[Problems to be solved by the invention]
However, in addition to the peak near 630 nm, this red LED shows a weak peak near 830 to 880 nm as shown by an arrow a in FIG. 7B. This indicates that the light emitted by the red LED includes light of the infrared component. The light of the infrared component does not attenuate when transmitting through the original, reaches an image sensor such as a charge-coupled device (CCD), and is output as a signal. The image is not read and a reddish image is obtained.
[0006]
In order to avoid such a problem, the infrared component light may be removed so as not to reach the original or the image sensor. However, if an infrared cut filter or the like is arranged to remove infrared component light, the infrared component light for defect correction described above is also removed, and defect correction cannot be performed. I will. Therefore, a light source that emits light containing only the infrared component and a light source that emits light of the visible component are separately arranged or switchably arranged, and only the portion of the visible component (particularly the red component) that emits infrared light is used. If the cut filter is used, the light of the infrared component for defect correction is not removed. However, there is a problem in that such an arrangement complicates the configuration and consequently increases the size of the entire apparatus.
[0007]
The present invention has been made in view of the above problems, and even when the infrared component light is included together with the visible component light, only the visible component light can be used for illumination, and for correcting defects. It is an object of the present invention to provide a small-sized lighting device that can also use light of the infrared component for illumination, and an image input device equipped with the lighting device.
[0008]
[Means for Solving the Problems]
The lighting device according to claim 1 has a first light emitting element that emits light including a visible component and an infrared component, and a second light emitting element that emits light including only an infrared component, A light-emitting unit in which the first light-emitting element and the second light-emitting element are arranged in different rows on a substrate; light of the visible component and light of the infrared component emitted from the first light-emitting element An optical element having a first surface that transmits any one of the above, and reflects the other, and a second surface that reflects the light transmitted through the first surface. 1 light-emitting element and the second light-emitting element, and the first surface and the second surface of the optical element, among light reflected from the first surface and the second surface. The light of the visible component emitted from the first light emitting element and the light emitted from the second light emitting element are guided to a common optical path. Characterized in that it is arranged to be.
[0009]
The lighting device according to claim 2 is the lighting device according to claim 1, wherein the visible component light emitted from the first light emitting element includes at least a red component light.
An image input device according to claim 3, wherein the illumination device according to claim 1 or 2, a condensing optical system that collects illumination light from the illumination device and irradiates the original with the illumination device, And an image reading unit that reads the image of the image data and obtains image data.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Hereinafter, as an example of the image input apparatus of the present invention, an image reading apparatus that reads an image printed on a film document by transmitted illumination will be described.
FIG. 1 is a block diagram illustrating a configuration of the image reading apparatus according to the present embodiment.
[0011]
As shown in FIG. 1, the image reading device 1 includes a scanner main body 2 and an adapter 4 for holding a film original 3. The adapter 4 is detachable from the scanner main body 2 and is attached to the scanner main body 2 by being inserted into the slot 5 of the scanner main body 2.
As shown in FIG. 1, an optical block 6, a motor 7, and a control unit 8 are provided in the scanner main body 2.
[0012]
The optical block 6 includes an illumination unit 9 disposed above the slot unit 5 described above, a lens 10 disposed below the slot unit 5, and a line CCD 11.
The illumination unit 9 is configured by LEDs of each of RGBI colors, and is sequentially turned on or off according to an instruction from the control unit 8.
[0013]
The illumination light from the illumination unit 9 is a linear light along the x direction (main scanning direction) in FIG. For this reason, the optical path of the illumination light from the illumination unit 9 and the film original 3 intersect at a predetermined line (hereinafter, referred to as a “read line 12”) along the x direction.
The lens 10 forms a linear light guided below the film original 3 via the reading line 12 on the imaging surface of the line CCD 11.
[0014]
The line CCD 11 is an image sensor in which a plurality of pixels are arranged one-dimensionally in the x direction, and accumulates charges corresponding to incident light in each pixel. Then, the line CCD 11 outputs the charge accumulated in each pixel to the control unit 8 as an analog signal.
The motor 7 moves the optical block 6 stepwise at fine intervals in the y-direction (sub-scanning direction) based on an instruction from the control unit 8. When the optical block 6 is moved in the y direction by the motor 7, the read line 12 also moves in the y direction.
[0015]
The control unit 8 controls the motor 7, the illumination unit 9, and the line CCD 11, and performs signal processing such as amplification and A / D conversion on the analog image signal output from the line CCD 11. Obtain digital image data.
The control unit 8 includes an external interface (not shown), and connects the image reading device 1 of the present invention to an external host computer 13.
[0016]
Note that the host computer 13 is also provided with an operation unit (not shown) such as a keyboard that receives a user operation such as an instruction to execute prescan and main scan.
Hereinafter, the lighting unit 9 which is a feature of the present invention will be described in detail.
The illumination unit 9 includes a light source unit 30, a condenser lens 31, and a mirror 32, as shown in FIG. The light emitted from the light source unit 30 is condensed by the condenser lens 31, guided downward by the mirror 32, and irradiated on the film original 3.
[0017]
FIG. 3A is a diagram of the light source unit 30 viewed from the direction of the arrow b in FIG. 2, and FIG. 3B is an enlarged view of the light source unit 30 viewed from the same direction as FIG.
As shown in FIG. 3A, the light source unit 30 includes a metal flat plate 33, red LEDs 34 and 35, green LEDs 36 and 37, blue LEDs 38 and 39, and infrared LEDs 40 and 41. Further, as shown in FIG. 3B, the light source unit 30 includes an optical element 42 and a diffusion plate 43.
[0018]
The red LEDs 34 and 35 are red LEDs having the spectral characteristics shown in FIG. 7B, and exhibit weak peaks near 830 to 880 nm in addition to 630 nm. A peak at 630 nm indicates red component light, and a peak near 830 to 880 nm indicates infrared component light. That is, the red LEDs 34 and 35 are light-emitting elements that emit light including a visible component and an infrared component. Hereinafter, this infrared component light is referred to as “infrared light derived from the red LED”. The infrared LEDs 40 and 41 are light-emitting elements that emit light containing only infrared components.
[0019]
LEDs serving as point light sources are arranged in two rows on the metal plate 33. In the first column, red LEDs 34 and 35 and green LEDs 36 and 37 are arranged in the order of red LED 34, green LED 36, green LED 37, and red LED 35. In the second column, blue LEDs 38 and 39 and infrared LEDs 40 and 41 are arranged in the order of blue LED 38, infrared LED 40, infrared LED 41, and blue LED 39.
[0020]
Here, the red LEDs 34 and 35 that emit infrared light derived from the red LEDs and the infrared LEDs 40 and 41 are arranged in different rows on the metal flat plate 33.
The optical element 42 is arranged so as to have an angle of 45 degrees with respect to the flat metal plate 33. The optical element 42 is a flat glass component, and a red-green reflecting mirror 44 which is a dichroic mirror that reflects red component light and green component light is formed on the first surface on the LED side. . A normal total reflection mirror 45 is formed on the second surface opposite to the LED.
[0021]
As shown in FIG. 4, the red-green reflecting mirror 44 reflects only light near 500 to 750 nm. Therefore, of the light applied to the red-green reflecting mirror 44, the red component light and the green component light are reflected, and the other light is transmitted.
Light emitted from each LED on the metal flat plate 33 enters the optical element 42, and light emitted from the optical element 42 passes through the diffusion plate 43 and is guided to the condenser lens 31 described above.
[0022]
The red LEDs 34 and 35 correspond to the “first light emitting element” in the claims, and the infrared LEDs 40 and 41 correspond to the “second light emitting elements” in the claim. The metal flat plate 33 corresponds to a “substrate” in the claims, and the control unit 8 and the LEDs 34 to 41 correspond to a “light emitting unit” in the claims. Further, the first column and the second column correspond to “different columns” in the claims. The red-green reflecting mirror 44 corresponds to a “first surface” in the claims, and the total reflection mirror 45 corresponds to a “second surface” in the claims.
[0023]
In addition, the infrared light derived from the red LED corresponds to the claim “light of an infrared component emitted from the first light emitting element”. The optical element 42 corresponds to “optical element” in the claims, and the light source unit 30 and the control unit 8 correspond to “illumination device” in the claims. Furthermore, the condenser lens 31 and the mirror 32 correspond to a “light collecting optical system” in the claims, and the motor 7, the lens 10, the line CCD 11, and the control unit 8 correspond to an “image reading unit” in the claims.
[0024]
Of the light emitted from the red LEDs 34 and 35 and the green LEDs 36 and 37 in the first row, the light excluding the infrared light derived from the red LED (the red component light emitted from the red LEDs 34 and 35 and the green LED 36 37) is reflected by the red-green reflecting mirror 44 on the first surface of the optical element 42. The light emitted from the blue LEDs 38 and 39 and the infrared LEDs 40 and 41 in the second row is not reflected by the red-green reflecting mirror 44 on the first surface of the optical element 42 but passes through it. , Refracted and proceed inside the optical element 42. Then, the light is reflected by the total reflection mirror 45 on the second surface of the optical element 42, refracted again by the red-green reflection mirror 44 on the first surface, and emitted outside the optical element 42.
[0025]
Further, the distance between the first and second rows of LEDs on the metal flat plate 33 and the thickness of the optical element 42 (the red-green reflecting mirror 44 on the first surface and the total reflection on the second surface). The interval between the mirror 45 and the red LED 34 and 35 and the green LED 36 and 37 excluding the infrared light derived from the red LED, the blue LED 38 and 39 and the infrared LED 40, 41 and the light emitted from the common light path 46 are guided to the common optical path 46. Note that the refractive index of the optical element 42 may be changed to guide the light to the common optical path 46.
[0026]
On the other hand, the infrared light originating from the red LED is not reflected by the red-green reflecting mirror 44 on the first surface of the optical element 42, passes through it, is refracted, and proceeds inside the optical element 42. Then, the light is reflected by the total reflection mirror 45 on the second surface of the optical element 42, refracted again by the red-green reflection mirror 44 on the first surface, and emitted outside the optical element 42. At this time, the infrared light derived from the red LED is guided to the optical path 47 shown by the broken line in FIG. 3B.
[0027]
That is, the light from the optical element 42 excluding the infrared light derived from the red LED is guided to the common optical path 46, and the infrared light derived from the red LED is guided to the optical path 47. The two optical paths (46, 47) are parallel to each other. Then, as shown in FIG. 2, the two optical paths are condensed by the condenser lens 31 while being parallel, and irradiate the film original 3 via the mirror 32.
[0028]
At this time, since the infrared light derived from the red LED passes through the optical path 47 deviated from the common optical path 46, the infrared light is refracted by the condenser lens 31 and forms an angle, and reaches a position distant from the reading line 12 on the film original 3. I do.
How far to reach the position depends on how far the common optical path 46 emitted from the optical element 42 and the optical path 47 of the infrared light derived from the red LED are. The distance between the common optical path 46 and the optical path 47 is determined by the spacing when the LEDs are arranged in two rows, the thickness of the optical element 42, and the refractive index.
[0029]
As described above, the infrared light derived from the red LED reaches a position on the film document 3 that is separated from the reading line 12. For this reason, since the infrared light derived from the red LED is not irradiated to the portion (the reading line 12) illuminating the area corresponding to one line read by the line CCD 11, the line CCD 11 does not substantially read the infrared light. Therefore, of the light emitted by the red LEDs 34 and 35, only the light of the red component can be used for illumination.
[0030]
On the other hand, the infrared component light emitted from the dust damage correction infrared LEDs 40 and 41 passes through the common optical path 46 and irradiates the reading line 12 on the film document 3. Therefore, the reading is performed by the line CCD 11, and the dust damage correction can be performed.
As described above, according to the present embodiment, the first light-emitting elements (red LEDs 34 and 35) that emit light including the visible component and the infrared component and the second light-emitting element that emits light including only the infrared component are provided. And the light emitting elements (infrared LEDs 40 and 41) are arranged in different rows on the metal flat plate 33, transmit infrared component light emitted from the red LEDs 34 and 35, and emit visible component light (red component light). And a second surface (total reflection mirror 45) that reflects light transmitted through the first surface, and a red LED 34, 35 The infrared LEDs 40, 41, the red-green reflection mirror 44, and the total reflection mirror 45 are configured such that, of the light emitted from the optical element 42, light excluding the infrared component light emitted from the red LEDs 34, 35 is transmitted through a common optical path. It is arranged to be guided to 46.
[0031]
Therefore, with a simple configuration, even when the infrared component light is included together with the visible component light, only the visible component light can be used for illumination. Further, in addition to the infrared component light included together with the visible component light, infrared component light for defect correction can be used for illumination. Further, in addition to the peak near 620 to 630 nm, a red LED having good color reproducibility showing a weak peak near 830 to 880 nm can be used, and an image with more preferable color reproduction can be obtained.
[0032]
Further, according to the present embodiment, by arranging the LEDs of each color in two rows, it is possible to reduce the size of the device, and further, it does not require a new member (such as an infrared cut filter and a light source switching mechanism). Therefore, the size of the entire apparatus can be further reduced.
In the present embodiment, an example in which the red-green reflection mirror 44 is formed on the first surface of the optical element 42 and the total reflection mirror 45 is formed on the second surface has been described. However, the first surface transmits one of the visible light component (red component) and the infrared component emitted from the red LED as the first light emitting element and reflects the other, and the second surface However, the optical element 42 may have any configuration as long as it reflects light transmitted through the first surface. For example, the configuration shown in FIGS. 5A and 5B may be used.
[0033]
As shown in FIG. 5A, on the metal flat plate 53, in the first row, LEDs are arranged in the order of blue LED 54, infrared LED 56, infrared LED 57, and blue LED 55. In the second column, red LEDs 58, green LEDs 60, green LEDs 61, and red LEDs 59 are arranged in this order. The red LEDs 58 and 59 are red LEDs having the spectral characteristics shown in FIG. 7B and include infrared light derived from the red LEDs.
[0034]
In the optical element 62, a blue / infrared reflecting mirror 64, which is a dichroic mirror that reflects blue component light and infrared component light, is formed on the first surface on the metal flat plate 53 side. A normal total reflection mirror 65 is formed on the second surface opposite to the flat metal plate 53.
As shown in FIG. 6, the blue / infrared reflecting mirror 64 reflects only light having a wavelength of 500 nm or less and a wavelength of about 720 nm or more. Therefore, of the light applied to the blue / infrared reflecting mirror 64, the blue component light and the infrared component light are reflected, and the other light is transmitted.
[0035]
Therefore, of the light applied to the optical element 62, the light excluding the infrared light derived from the red LED is guided to the common optical path 66. On the other hand, since the infrared light derived from the red LED is guided to the optical path 67 shifted from the common optical path 66, the same effect as in the configuration described with reference to FIGS. 3A and 3B can be obtained.
[0036]
【The invention's effect】
As described above, according to the present invention, even when the infrared component light is included together with the visible component light, only the visible component light can be used for illumination, and the infrared light for defect correction can be used. It is possible to provide a small-sized lighting device that can also illuminate the component light, and an image input device provided with the lighting device.
[Brief description of the drawings]
FIG. 1 is a functional block diagram of an image reading apparatus according to an embodiment.
FIG. 2 is a configuration diagram of an illumination unit of the image reading apparatus according to the embodiment.
FIG. 3 is a diagram illustrating an illumination unit of the image reading apparatus according to the embodiment.
FIG. 4 is a graph showing the reflection characteristics of a red-green reflection mirror.
FIG. 5 is a diagram illustrating an illumination unit of the image reading apparatus according to the embodiment.
FIG. 6 is a graph showing reflection characteristics of a blue / infrared reflecting mirror.
FIG. 7 is a diagram illustrating characteristics of a red LED.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Image reading apparatus 2 Scanner main body 3 Film original 4 Adapter 5 Slot part 6 Optical block 7 Motor 8 Control part 9 Illumination part 10 Lens 11 Line CCD
12 Reading Line 13 Host Computer 30 Light Source 31 Condenser Lens 32 Mirror 33,53 Metal Plate 34,35,58,59 Red LED
36,37,60,61 Green LED
38,39,54,55 Blue LED
40, 41, 56, 57 infrared LED
42, 62 Optical elements 43, 63 Diffusion plate 44 Red-green reflection mirror 45, 65 Total reflection mirror 46, 66 Common optical path 47, 67 Optical path 64 Blue / infrared reflective mirror

Claims (3)

A first light-emitting element that emits light containing a visible component and an infrared component; and a second light-emitting element that emits light containing only an infrared component. A light-emitting section in which the light-emitting elements are arranged in different rows on the substrate,
A first surface that transmits one of the visible component light and the infrared component light emitted from the first light emitting element and reflects the other; and a light that transmits the first surface. An optical element having a second surface that reflects
The first light emitting element and the second light emitting element of the light emitting section, and the first surface and the second surface of the optical element are separated from the first surface and the second surface. In the reflected light, the light of the visible component emitted from the first light emitting element and the light emitted from the second light emitting element are arranged to be guided to a common optical path. Lighting equipment. The lighting device according to claim 1,
The lighting device according to claim 1, wherein the visible light emitted from the first light emitting element includes at least a red light. A lighting device according to claim 1 or 2,
A condensing optical system that collects illumination light from the illumination device and irradiates the original with light;
An image input device comprising: an image reading unit that reads an image of the document and obtains image data.

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