JP2830523B2 - Solid-state imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device used for an image input device such as a facsimile, a copying machine, etc., and more particularly to a solid-state image pickup device having a photoelectric conversion element formed on a transparent insulating substrate. .

[0002]

2. Description of the Related Art In recent years, as various OA devices such as facsimile machines and copiers have been reduced in size, speed, and color, there has been a strong demand for high speed color for image sensors, which are main image input electronic components. I have. What is very important for speeding up the image sensor is the response of light signals to light and dark (referred to as light responsiveness). By improving the optical response, the afterimage of the image sensor (a phenomenon in which the signal of the previous stage or the previous line partially remains and remains in the next stage) is reduced, the driving frequency is increased, and a large contribution is made to higher speed. it can.

Conventionally, as a means for improving the optical response of an image sensor, a method using bias light has been widely known. For example, an image reading apparatus described in Japanese Patent Publication No. 52-4436 has an improved transfer efficiency using bias light for a CCD sensor. Japanese Patent Publication No. 55-35748 proposes using a bias light for a phototransistor to improve the operating point level. JP-A-62-204657 and JP-A-2-234563 disclose a-Si and C.
It is described that bias light is applied to a thin-film photoelectric conversion element such as dS or CdSe to reduce traps in the photoelectric conversion film and improve operating characteristics.

[0004] In such an image reading apparatus using bias light, how to guide the bias light to the image sensor poses a problem.

As one example of the prior art, Japanese Patent Application Laid-Open No. 62-20 / 1987
An apparatus disclosed in Japanese Patent No. 4657 will be described with reference to FIG. In the figure, 51 is an image sensor, 52 is its photoelectric conversion element, 53 is an imaging lens, 54 is a light source for document illumination,
55 is a bias illumination light source, and 56 is a document. Manuscript 5
An image on the image sensor 6 is formed by an image forming lens 53 on the image sensor 5.
This is read by one photoelectric conversion element 52. In this example, the light sources include a document illumination light source 54 and a bias illumination light source 55, but these are the same type of light source. The light from the document illumination light source 54 is reflected by the document 56 and forms an image on the photoelectric conversion element 52 of the image sensor 51 through the imaging lens 53. The light from the bias illumination light source 55 passes directly through the photoelectric conversion element 52 without passing through the imaging lens 53.
Is guided. Thus, the bias illumination light source 55
In this case, the light responsiveness of the image sensor 51 is to be improved by making the steady light from the photoelectric conversion element 52 incident on the photoelectric conversion element 52.

As described above, when the bias light is applied, a total photocurrent of the photocurrent due to the bias light and the photocurrent due to the signal light which is the reflected light from the document flows. In order to obtain a signal component, the photocurrent due to the bias light must be subtracted from the total photocurrent. In the case of a line sensor, a constant value is subtracted as the bias light component. Therefore, when there is a large variation among the individual photoelectric elements, the relative variation of the signal components from which a certain value is subtracted becomes very large.

To improve this, a photoelectric conversion device in which the photocurrent component due to the bias light is reduced and the light response speed is extremely increased is described in Japanese Patent Application Laid-Open No. 63-102453. The photoelectric conversion device described in this publication is a photoelectric conversion device in which a light-shielding film having a window, a transparent insulating film, and a photoconductive element provided with a counter electrode on a photoconductive film are sequentially laminated on an insulating substrate. A plurality of elements are arranged side by side in the main scanning direction, a transparent protective film is laminated thereon, and the original is illuminated by illumination light from a light source arranged on the back of the substrate, and reflected light from the original is converted into an electric signal by a photoelectric conversion device. Is converted to As the photoconductive element, an element exhibiting an S-shaped rising characteristic is used. The light-shielding film has a limited amount of light-transmitting property on a shorter wavelength side than a specific wavelength, so that, of the light from the light source, the short-wavelength light transmitted through the light-shielding film directly hits the photoconductive element. , And bias light.

Here, consider the case where the reading system is colored. For example, a three-primary color system will be described. The reflected light of the original is separated by three color filters of R, G and B,
Usually, in the case of a photoelectric conversion element such as a-Si, the amount of afterimage changes depending on the wavelength of light or the amount of light. FIG. 14 is a diagram showing an afterimage amount when a bias light amount is applied. The horizontal axis represents the ratio of the amount of bias light to the original reflected light, and the vertical axis represents the residual image amount in percentage.
The measurement conditions were as follows: a-μm-thick a-
The measurement was performed at a bias light wavelength of 570 nm and an all white output of 1 V using Si. The residual image amounts of the fourth and eighth lines sharply decrease with respect to the residual image amount of the first line. The afterimage time can be estimated from this reduction rate. Also,
It can be seen that the larger the ratio of the bias light, the smaller the amount of afterimage. However, as described above, when the ratio of the bias light is increased, there is a problem that the variation of the individual photoelectric elements becomes large.

If the amounts of afterimages differ among the three colors, R,
When the three color signals of G and B are mixed, a color shift (also referred to as a color ghost) occurs in a monotone original, and
Significant image quality degradation will result. Therefore, in the case of a color reading system, it is necessary to make the amount of residual images between the three colors as uniform as possible. FIG. 15 shows an experimental result of measuring the dependency of the afterimage on the wavelength. The measurement was performed under the same measurement conditions as in FIG.
An all-white original was illuminated up to eight lines, where the light source was turned off and the amount of afterimage was plotted. It was found that there was a difference in the amount of afterimage at 570 nm and 660 nm, and the wavelength dependence of afterimage was confirmed.

In the photoelectric conversion device described in Japanese Patent Application Laid-Open No. 63-102453, the bias light source directly incident on the photoelectric conversion element and the light source for document illumination are the same light source, and the bias light is used for document illumination. It is obtained by dispersing the working light with a light shielding film. Therefore, it is difficult to appropriately select the optimal light wavelength and light amount, and it is almost impossible to use the color reading system in terms of image quality.

Further, the above-mentioned Japanese Patent Application Laid-Open No. 62-204657.
There is also a problem when using the device described in Japanese Patent Application Publication No. JP-A-2006-115139 for a color image sensor. Usually, in the case of a color image sensor, a color filter for color separation is arranged on the photoelectric conversion element. As a matter of course, the color filter is located on the incident side of the original reflected light. On the other hand, since the bias light also enters from the same side, depending on the wavelength, there are cases where the light cannot pass through the color filter, and the bias light cannot enter the photoelectric conversion element. For example, a color image sensor having three primary color filters has a spectral sensitivity as shown in FIG. 18, but here, a red LED having an emission spectrum characteristic as shown by a curve 64 was used as a light source for bias illumination. In this case, the bias light does not reach the blue sensing element 61 and the green sensing element 62. Even if a light source such as a white fluorescent lamp is used as a bias illumination light source, the wavelengths of the bias light reaching the blue, green, and red elements 61, 62, and 63 are different from each other. The residual image amount differs for each color due to the wavelength dependence of the response. Therefore, even if the apparatus described in Japanese Patent Application Laid-Open No. 62-204657 is used, it is difficult to obtain a good image by deteriorating color reproducibility and causing problems such as color misregistration.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is intended to effectively improve the light responsiveness of a color image sensor by bias light. Accordingly, it is an object of the present invention to provide a color image sensor capable of high-speed reading.

[0013]

According to a first aspect of the present invention, there is provided a solid-state imaging device having a photoelectric conversion element provided on a transparent substrate, wherein the first photoelectric conversion element applies reflected light from an original to the photoelectric conversion element. Light source means, and second light source means for applying bias light to the photoelectric conversion element via an optical waveguide formed on the transparent substrate, wherein the second light source means irradiates light having different spectra, respectively. And a plurality of bias light sources.

According to a second aspect of the present invention, in the solid-state imaging device according to the first aspect, a light amount adjusting means for selectively adjusting the light amount of the bias light source is provided.

According to a third aspect of the present invention, there is provided a solid-state imaging device having a photoelectric conversion element provided on a transparent substrate, wherein the color filter provided on one side of the photoelectric conversion element sandwiches the transparent substrate. A first light source means for directing reflected light from a document to the photoelectric conversion element from one side via the color filter, and the first light source means to the photoelectric conversion element from the other side sandwiching the transparent substrate. Second light source means for applying bias light having different emission spectra,
The photoelectric conversion elements are provided on a large number of transparent substrates to form an array, and the arrays are further arranged side by side. The second light source means is constituted by a bias light source provided in each array, respectively. And a light amount adjusting means for adjusting the light amount of the bias light source.

[0016]

[0017]

The operation of the present invention will be described. FIG.
In a solid-state imaging device provided with a photoelectric conversion element on a transparent substrate, it is an explanatory diagram of a case where bias light is applied to the photoelectric conversion element via an optical waveguide formed on the transparent substrate,
It is an expanded sectional view near the end of an insulating transparent substrate. In the figure,
31 is a first transparent insulating substrate, 32 is a light shielding member, 33 is a second transparent insulating substrate, and 34 is an LED solid light source.
The second transparent insulating substrate 33 is the first transparent insulating substrate 3
The light-shielding member 32 is provided on the first transparent insulating substrate 33 on the side of the second transparent insulating substrate 33. The LED solid light source 34 is provided on the side of the first transparent insulating substrate 31.

Light emitted from the LED solid-state light source 34 enters the first insulating transparent substrate 31 from its side surface at various angles. Here, assuming that the optical refractive index of the first insulating transparent substrate 31 is about 1.5 and the optical refractive index of air is 1.0, θ = sin ⁻¹ (1.0 / 1.5) = The total reflection angle is obtained from 42 °. That is, Y shown in FIG.
A light beam whose incident angle θ with respect to the −Y line becomes 42 ° or more repeats total reflection inside the first insulating transparent substrate 31. On the other hand, light that does not enter from the side surface of the first insulating transparent substrate 31 is reflected on the upper surface of the first insulating transparent substrate 31, but is provided on the side surface of the second insulating transparent substrate 33. The second insulating transparent substrate 3 is hindered by the light shielding member 32.
No light is incident on the inside of 3. Then, the light that has been totally reflected inside the first insulating transparent substrate 31 is reflected by the photoelectric conversion element as shown in FIG.
Is guided as bias light 29 from the opposite side. In addition,
FIG. 5 shows an example of a photodiode using a photoelectric conversion film 23 of a hydrogenated amorphous silicon (a-Si: H) thin film, which will be described in detail later, and is sandwiched between a lower electrode 22 and an upper transparent electrode 24. A-Si photoelectric conversion film 23
From the area where the lower electrode 22 does not exist.
9 shows a state where light is incident. Since the optical refractive index of a-Si is as large as about 3.5, the light incident on the inside of the first transparent insulating substrate 21 hardly exits to the outside, and the photoelectric conversion film is efficiently formed. Absorbed by 23.

As described above, the bias light can be applied to the photoelectric conversion element from the side opposite to the original reflected light.
The bias light is absorbed to a certain depth in the photoelectric conversion film in accordance with the wavelength, and functions to steadily fill a localized level that causes deterioration of photoresponsiveness. Therefore, the carrier generated by the original reflected light is taken out as a signal without being trapped at the localized level, and the light responsiveness of the image sensor can be improved.

The operation when the bias light is applied to the photoelectric conversion element from below will be described with reference to FIG. FIG. 10 is an enlarged sectional view near the photoelectric conversion element. The same parts as those in FIG. 5 are denoted by the same reference numerals, and a detailed description thereof will be apparent from the description of FIG. Since the light emitted from the light source provided on the back side of the insulating transparent substrate 21 enters from almost immediately below the photoelectric conversion element, the optical refractive index of the insulating transparent substrate 21 becomes 1.5.
If it is on the order, the light reaches the photoelectric conversion element with almost no reflection on the substrate surface. The photoelectric conversion element is a photoelectric conversion film 23
FIG. 1 shows an example in which two photodiodes each using a hydrogenated amorphous silicon (a-Si: H) thin film are connected in series so as to have opposite polarities, and is sandwiched between a lower electrode 22 and an upper transparent electrode 24. Made of the photoelectric conversion film 23. Bias light 29 transmitted through insulating transparent substrate 21
Indicates that the photoelectric conversion film 23 is removed from the region where the lower electrode 42 does not exist.
Incident on. The optical refractive index of the photoelectric conversion film 23 is about 3.
5, which is extremely large, the light that has entered the inside of the photoelectric conversion film 23 is efficiently absorbed by the photoelectric conversion film 23 without being emitted to the outside.

As described above, it is possible to cause the bias light to enter the photoelectric conversion element from the side without the color filter, and to irradiate the color-separated elements with the bias light having the same wavelength. . As described with reference to FIG. 5, the bias light is absorbed to a certain depth in the photoelectric conversion film in accordance with the wavelength, and functions to constantly fill a localized level that causes deterioration of photoresponsiveness. . Therefore,
The carrier generated by the original reflected light is taken out as a signal without being trapped at the localized level, and the light responsiveness of the image sensor can be improved.

[0022]

FIG. 1 is a schematic diagram of a first embodiment. In the figure, 10 is a document, 11 is a support plate, 12 is a first insulating transparent substrate, 13 is a second insulating transparent substrate, 14 is a photoelectric conversion element, 15 is a color filter, 16 is a light shielding member, 17 is An LED solid light source, 18 is an LED wiring board, 19 is a lens, and 20 is a light source for document illumination. The first insulating transparent substrate 12 and the LED wiring board 18 are supported. The first insulating transparent substrate 12 is made of Corning Glass 7059
(Corning's refractive index 1.54, plate thickness 1.1mm)
Are used. On the first insulating transparent substrate 12, 1
One or a plurality of photoelectric conversion elements 14 are provided to form a light receiving section. The second insulating transparent substrate 13 is the same as the second insulating transparent substrate 12, except that a color filter array including a color filter 15 is formed on the lower surface. These two insulating transparent substrates are bonded together by using an ultraviolet curable resin or the like so that the film surfaces are bonded to each other, thereby forming a color image sensor having color resolution. The color image sensor is bonded to a support plate 11 which also serves as a wiring substrate such as a ceramic. A light-shielding member for the side surface of the second insulating transparent substrate 13 on the side where the bias light source is installed,
For example, by using a silicone resin JCR6125 black (manufactured by Toray Silicone Co., Ltd.) or the like, light is shielded to prevent light from the LED solid light source 17 as a bias light source from entering the inside of the second insulating transparent substrate 13. . Also, on the support plate 11, near the side surface of the first insulating transparent substrate 12,
An LED array including the LED solid-state light source 17 and the LED wiring board 18 is provided at a position in which light use efficiency and uniformity are optimized. Light incident from the LED solid light source 17 into the inside of the first insulating transparent substrate 12 is:
As described above, since it has the characteristic of having total light reflection, that is, the light scattering effect, it reaches the photoelectric conversion element 14 as light having ideal uniformity as bias light. On the other hand, a lens 19 for image formation is provided on the color filter array side of the color image sensor. The lens 19 used was a converging fiber (Nippon Sheet Glass Co., Ltd., Selfoc lens, etc.) on an array. The document 10 is illuminated by a document illumination light source 20, for example, a daylight fluorescent lamp, and the light reflected by the document 10 is imaged on the photoelectric conversion element 14 by a lens 19. Accordingly, the reflected light of the original document color-separated by the color filter 15 can be made incident on the photoelectric conversion element 14, and the bias light having an appropriate wavelength and good uniformity is not affected by the color filter 15. To
It is possible to irradiate the photoelectric conversion element 14 of each color.

As the photoelectric conversion element 14, in this embodiment, two photodiodes made of a hydrogenated amorphous silicon (a-Si: H) thin film are connected in series so that they have opposite polarities. FIG. 5 shows an example. In the drawing, 21 is a first insulating transparent substrate, 22 is a metal electrode, 23 is a hydrogenated amorphous silicon thin film photoelectric conversion layer, 24 is a transparent electrode, 25 is an insulating resin, 26 is an extraction electrode, and 27 is a protective film. , 28 are original reflected light and 29 is bias light. Each photoelectric conversion element includes a metal electrode 22 made of Cr or the like, discretely arranged on a first insulating transparent substrate 12, a strip-shaped photoelectric conversion layer 23 made of a hydrogenated amorphous silicon thin film, indium tin oxide, or the like. And a blocking diode B are sequentially laminated and patterned.
D is formed. The photodiode PD and the blocking diode BD are connected in series in a state where the polarity is reversed by sharing the metal electrode 22 on the cathode side. The photodiode PD and the blocking diode BD are covered with an insulating layer 25 made of polyimide or the like, and a lead wire 26 made of aluminum or the like is connected to the insulating layer 25 via a contact hole formed by photolithography. . The document reflected light 28 enters the opening defined by the lead-out wiring 26 from above and forms an image.

FIG. 2 shows a second embodiment. In this drawing, the illustration of the original, lens, light source for illuminating the original, and the like is omitted. In the figure, the same parts as those in FIG. 16a and 16b are light shielding members, 17a and 17
b is an LED solid light source, and 18a and 18b are wiring boards. In this embodiment, LED solid-state light sources 17a and 17b are mounted on the wiring boards 18a and 18b, respectively, near both sides of the first insulating transparent substrate 12, and the appropriate positions are set as in the embodiment of FIG. To place. Further, on the side surface of the second insulating transparent substrate 13, light shielding members 16a and 16b are provided on both sides. In such a configuration, when the wavelength characteristics of the LED solid-state light sources 17a and 17b are the same, the amount of bias light is increased, and a margin in optical design is increased. Further, since the optimum wavelength of the bias light changes depending on the material and the thickness of the photoelectric conversion element 14 used, if the wavelength characteristics of the LED solid-state light sources 17a and 17b are different (for example, 570 nm and 660 nm), the photoelectric conversion can be performed. Variations such as variations in the film thickness of the element 14 can be absorbed.

FIG. 3 shows a third embodiment. 2, illustration of a document, a lens, a light source for document illumination, etc. is omitted, and the same parts as those in FIG. 16c is a light shielding member. In this embodiment, the first
The color filter 15 is directly mounted on the photoelectric conversion element 14 on the insulating transparent substrate 12. In this case, LED
In order to prevent light from the solid light source 17 from being incident on the color filter side, a light shielding member 16c is provided near the photoelectric conversion element 14 as shown in the figure. The viscosity of the light shielding member 16c was adjusted so that the height of the light shielding member 16c was at least higher than the upper surface of the LED solid-state light source 17, and the light shielding member 16c was mounted on the first insulating transparent substrate 12 using a dispenser or the like. The light-blocking member may be mounted by stacking a plurality of stages.

FIG. 4 shows a fourth embodiment. This embodiment is different from the second embodiment in that the color filter 15 is
Photoelectric conversion element 14 directly on first insulating transparent substrate 12
It is provided in. In the figure, the same parts as those in FIG. 16d, 16e
Is a light shielding member, 17d and 17e are LED solid light sources, 18
d and 18e are wiring boards. Similarly to the third implementation example,
Light shielding materials 17 d and 17 e are provided on both sides of the photoelectric conversion element 14. Regarding the effect of this implementation example, the same effect as that described in the second embodiment can be obtained.

FIG. 7 shows a fifth embodiment. In the figure,
The same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. 17c is an LED solid light source, 18c is a wiring board. In this embodiment, a metal material is used for the support plate 11, and an opening is provided at the center. First insulating transparent substrate 1
2. The photoelectric conversion element 14 is the same as in the first embodiment. A color filter 15 is provided on the photoelectric conversion element 14.
Are formed by a dyeing method using a photolithography technique or the like, and constitute a color image sensor having color resolution. The color image sensor is bonded on a metal support plate 11 of Al or the like. This metal support plate 1
Reference numeral 1 denotes a reinforcing member for the image sensor substrate and also serves to ground the image sensor circuit. An opening of the support plate 11 directly below the photoelectric conversion element 14 forms an entrance window for bias light. On the other hand, the LED wiring board 1 on which the LED solid-state light source 17c and its protection resistor are mounted.
The LED array made of 8c is attached to the support plate 11 as shown in the figure. Since the plate thickness of the first insulating transparent substrate 12 is 1.1 mm and the bias light is incident on the photoelectric conversion element 14 from immediately below, the light energy can be used efficiently.

FIG. 8 shows a sixth embodiment. In the figure,
The same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. 17d is an EL light source. In this embodiment, an EL light source 1 is provided between a first insulating transparent substrate 12 and a support plate 11.
7b was provided with its light emitting surface facing the photoelectric conversion element 14. The EL light source 17d may be a dispersion-type EL element made by using a general thick film technique. For example, ZnS: Cu, C
l-system (blue-green 450-570 nm), ZnS: Cu, A
1-based (blue-green 530 nm), ZnS: Cu, Br-based (green 490-570 nm), ZnS: Cu, Mn, Cl-based (yellow 587 nm), ZnCdS: Cu, Br-based (red 630 nm), and the like. . About the wavelength, depending on the material, film thickness, etc. of the photoelectric conversion element 14 to be used.
Since the optimum wavelength of the bias light changes, the photoelectric conversion element 14
And the EL light source 17d is appropriately selected and used. In this embodiment, since the EL light source 17b is very thin, the whole color image sensor can be downsized.

FIG. 9 shows a seventh embodiment. In the figure,
The same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. 17e is a cold cathode fluorescent lamp, 18e is a wiring board.
In this embodiment, similarly to the fifth embodiment, an opening is provided in the support plate 11, and the fluorescent lamp unit including the cold cathode fluorescent lamp 17e and the wiring board 18e directs the light emitting unit toward the photoelectric conversion element 14. It is provided. Cold cathode fluorescent lamp 17
The emission color of e can be variously selected over the entire visible light range depending on the fluorescent material inside the tube. Further, in this embodiment, unlike the hot cathode fluorescent lamp, the cold cathode fluorescent lamp 17e is relatively small (5 to 8 mm in diameter), and can be reduced in size, and has a long life, reliability, stability, and price. It has the characteristic that it is excellent in such points.

In the cases described in the first to seventh embodiments, a photodiode type image sensor using a hydrogenated amorphous silicon (a-Si: H) thin film is used for all the photoelectric conversion elements 14. But also,
The present invention is applied to a CCD type, a MOS type, a bipolar transistor type, a phototransistor type, a photoconductive type using CdS-CdSe, and the like using an insulating transparent substrate as a photoelectric conversion element substrate. Is what you can do.

Such a color image sensor can be of a wide width. A long A0 width will be described. 11 is a plan view, FIG. 12 is a side view, and FIG.
It is an equivalent circuit diagram of a D array. In the figure, 41 is a support plate, 4
2 is a sensor glass array, 43 is a filter array, 44
Is an LED array, and 45 is a current control resistor. LE
The D array was divided into six groups so that the bias light sources could be adjusted independently. By adjusting the light amount of the bias light source, the sensitivity difference between the photoelectric conversion elements can be adjusted. As shown in FIG. 13, the connection of each LED is performed by connecting a plurality of, for example, three in series, connecting them in parallel, and connecting one group at a time to a power supply via a current control resistor. I have. The amount of light for each group can be adjusted by the current control resistor. Finer adjustment is possible by adjusting the resistors inserted in each series circuit.
Of course, each LED is arranged for each photoelectric conversion element,
The amount of bias light from each LED may be adjustable.

It has been described that the optimum wavelength of the bias light changes depending on the material and the thickness of the photoelectric conversion element used. FIG. 16 is an explanatory diagram of an experimental result of an example of a relationship between the optimum wavelength of the bias light and the film thickness of the photoelectric conversion element. As the film thickness increases, the optimum wavelength tends to shift toward longer wavelengths.

[0033]

As is apparent from the above description, according to the present invention, the incident side of the original reflected light with respect to the color image sensor comprising the photoelectric conversion element and the color filter array on the transparent insulating substrate is provided. From the opposite side, it is possible to irradiate all the photoelectric conversion elements with the same wavelength and uniform bias light. Therefore, there is an effect that a solid-state imaging device capable of high-speed reading with a high light response speed without impairing the color reproducibility of a document can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of a third embodiment of the present invention.

FIG. 4 is an explanatory diagram of a fourth embodiment of the present invention.

FIG. 5 is an enlarged sectional view of a photoelectric conversion element portion according to an example of the present invention.

FIG. 6 is an enlarged cross-sectional view near the edge of the insulating transparent substrate according to the example of the present invention.

FIG. 7 is an explanatory diagram of a fifth embodiment of the present invention.

FIG. 8 is an explanatory diagram of a sixth embodiment of the present invention.

FIG. 9 is an explanatory view of a seventh embodiment of the present invention.

FIG. 10 is an enlarged sectional view of a photoelectric conversion element according to another embodiment of the present invention.

FIG. 11 is a plan view of a color image sensor according to an embodiment of the present invention.

FIG. 12 is a side view of FIG.

FIG. 13 is an equivalent circuit diagram of the LED array of FIG.

FIG. 14 is a diagram showing the relationship between the amount of bias light and the amount of afterimage.

FIG. 15 is a diagram illustrating a relationship between a light source wavelength and an afterimage amount.

FIG. 16 is an explanatory diagram of a relationship between an optimum bias light wavelength and a photoelectric conversion element film thickness.

FIG. 17 is an explanatory diagram of a conventional solid-state imaging device using bias light.

FIG. 18 is an explanatory diagram of the spectral spectrum of the original reflected light and the bias light to the photoelectric conversion element.

[Explanation of symbols]

Reference Signs List 10 original, 11 support plate, 12 first insulating transparent substrate, 13 second insulating transparent substrate, 14 photoelectric conversion element, 15 color filter, 16 light shielding member, 17 L
ED solid light source, 18 LED wiring board, 19 lens,
20 Light source for document illumination.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04N 1/028 H04N 1/19 H04N 5/335

Claims (3)

(57) [Claims] 1. A solid-state imaging device having a photoelectric conversion element provided on a transparent substrate, wherein said first light source means irradiates reflected light from a document to said photoelectric conversion element, and an optical waveguide formed on said transparent substrate. And a second light source means for applying a bias light to the photoelectric conversion element via the second light source means, wherein the second light source means is constituted by a plurality of bias light sources each irradiating light having a different spectrum. Solid-state imaging device. 2. The solid-state imaging device according to claim 1, further comprising a light amount adjusting unit for selectively adjusting the light amount of the bias light source. 3. A solid-state imaging device in which a photoelectric conversion element is provided on a transparent substrate, wherein the color filter is provided on one side of the photoelectric conversion element and one of the transparent substrates sandwiches the color filter. First light source means for directing reflected light from a document to the photoelectric conversion element, and bias light having an emission spectrum different from that of the first light source means to the photoelectric conversion element from the other side of the transparent substrate. A plurality of photoelectric conversion elements are provided on a transparent substrate to form an array, and the arrays are arranged in parallel. The second light source means is provided in each array. A solid-state imaging device, comprising: a bias light source provided for each bias light source; and light amount adjusting means for adjusting a light amount of each bias light source.