JPH05235319A - Contact type two-dimensional image sensor - Google Patents

Abstract

PURPOSE:To see that always favorable image read can be done even if there is a change of intensity in a light source beam or distribution of concentration behind a manuscript by equipping it with a light-shielding film at on side of the periphery of a sensor substrate. CONSTITUTION:The figure shows the sectional structure of the pigment in a light level of reference line. This is equipped on a distance-to-manuscript adjusting layer 38, with a light-shielding film 39, and this light-shielding film 39 reflects the light at the manuscript face and guides it to a photosensor, so the light always in light condition is read out. This way, at least on one side of the periphery of an image reader, this is equipped, on the manuscript face, with the light-shielding film 39 as the structure of a photosensor, and a row of pigments for reading out a light level is arranged, whereby even if the illuminance of the manuscript face changes in variously, a light level geared to the change can be obtained. Accordingly, if image reading operation is performed, a light or dark level can be obtained, automatically without using a reference white and black manuscript.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-dimensional image sensor (two-dimensional image sensor) used for image input to a computer, image input to a facsimile, character input, or image information input to a device that handles other image information. Input device).

[0002]

2. Description of the Related Art In a device for inputting image information to a computer, a word processor, a facsimile, or the like, that is, an image input (reading) device, it is difficult to properly set black level, white level, correct shading and the like.

Japanese Patent Laid-Open Publication No.
There are 2-288657 and JP-A-2-252363.
The former discloses a method of irradiating a light source beam prior to reading, storing white level data in a memory, setting an original, and performing an image reading operation again to perform proper image reading. Further, in the latter, there is disclosed a method in which a background density level is detected at the time of reading an original, and an A / D converter is controlled by the obtained density level signal to favorably binarize an image signal.

[0004]

In the prior art, (1)
From the viewpoint of performing shading correction, a reading operation is performed using a white reference plate in order to determine a white level immediately before reading a document. Therefore, human hands were needed many times.
(2) Since the black level is determined by reading the background density on the surface of the original, it is difficult to read the original faithfully because the dynamic range of the reading device fluctuates for originals with different background densities.

An object of the present invention is to realize a two-dimensional image sensor which is simple and can always read a good image even when the intensity of a light source beam changes or the background of an original has a density distribution. Especially. More specifically, (1) a single reading operation for reading an original obtains intensity data (light level signal) of a light source ray, performs shading correction by this signal, and an amplifier for amplifying an image signal. Always control to an appropriate amplification factor.
(2) Regardless of the background density of the original, the amplifier that amplifies the image signal is always controlled to an appropriate amplification factor. (3) Control the offset of the amplifier that amplifies the image signal so that it is always in an appropriate state, regardless of the background density of the original.
(4) After reading the original, even if the read data is data including shading of the light source, appropriate correction is performed on the reproduced image to obtain a good image.

(5) The data (black level signal) in the case where there is no light source beam is obtained by one reading operation for reading the original, and the black level of the signal processing circuit is controlled to always be an appropriate value by this data. And so on.

[0007]

A light-shielding film is provided on a document surface as a structure of an optical sensor on at least one side of an outer peripheral portion of an image reading unit, and light incident from a sensor substrate side is reflected by the light-shielding film. A pixel column for guiding the reflected light to the photosensor and reading the bright level, or a pixel column for reading the dark level signal provided with a light shielding film near the photoelectric conversion element was arranged. At the time of image reading operation, a light / dark level signal is obtained, and this light / dark level signal is used as follows.

(1) The light and dark level signals control the amplifier that amplifies the photosensor output signal.

(2) The output signal of the sensor is amplified by an A / D
After passing through the converter, the image data is stored in the memory for recording the image information together with the light level signal and the dark level signal,
In outputting this image data, the image data was arithmetically processed using the light level signal and the dark level signal, and the reproduced image was obtained using this.

(3) The light level signal and the dark level signal are stored in separate memories, and the data in this memory is used to control the amplification factor and offset of the amplifier for amplifying the output signal of the two-dimensional image sensor. ..

(4) The level of the clamp circuit which is the video signal processing circuit of the photosensor output signal is controlled by the dark level signal.

[0012]

As a structure of the optical sensor, a light-shielding film is provided on the document surface on at least one side of the outer periphery of the image reading unit, and a pixel array for reading a light level or a light-shielding film near the photoelectric conversion element is provided. By arranging the pixel columns for reading out the level signal, even if the illuminance on the document surface changes variously, a bright level signal corresponding to the change can be obtained. Further, both signals can be obtained by the arrangement method of the light shielding film as the structure of the sensor. Therefore, when the image reading operation is performed, the brightness level signal is automatically obtained without using the reference black and white original.

By controlling the amplifier that amplifies the light sensor output signal by using the light and dark level signals of the present photosensor, even when the light source intensity is various, the white signal and the black signal are always optimal. It can be a value.

After passing the output signal of the sensor through the amplifier and the A / D converter, the image data is stored in the memory for recording the image information together with the light level signal and the dark level signal. By processing the image data using the level and dark level signals,
Optimal image reproduction is always performed.

By storing the light level signal and the dark level signal in separate memories and controlling the amplification factor and offset of the amplifier for amplifying the output signal of the two-dimensional image sensor by using the data in this memory, The optimum offset condition can be easily set, and shading correction can be performed easily.

By controlling the level of the clamp circuit which is the video signal processing circuit of the photosensor output signal by the dark level signal, the level of the black signal can always be kept at an optimum value.

[0017]

First Embodiment First, FIG. 1 shows a circuit configuration of a two-dimensional image sensor. The vertical scanning line 11 is a wiring for sequentially selecting read rows by a vertical scanning circuit (vertical driver). The signal reading circuit driven by the horizontal scanning circuit (horizontal driver) sequentially reads the image signal of each pixel using the signal line 21.
Two-dimensional image information can be obtained by the matrix of the vertical scanning lines 11 and the signal lines 21. One section of this matrix is one pixel. Each pixel has a pixel switch, a light receiving element, and a storage capacitor. The pixel switch closes the switch when reading the signal in the pixel. In addition, the light receiving element is a photosensor such as a phototransistor, a photodiode, or a photoconductor that moves electric charges according to the light intensity. The storage capacitor is a means for ascertaining the amount of electric charge that the light receiving element moves during the time when the signal reading operation is not performed.

FIG. 2 is a schematic view of a two-dimensional image sensor. In this embodiment, the light level reference line is added to the second line as the second line.
A dark level reference line was provided as a line, and an image reading line was provided after the third line.

FIG. 3 shows a cross-sectional structure of a bright level reference row pixel portion. Further, FIG. 4 shows a sectional structure of a pixel portion in a dark level reference row, and FIG. 5 shows a sectional structure of a pixel portion in an image reading row. Each of the drawings shows a pixel structure including a pixel switch section, a storage capacitor section, and a gap-type photo sensor, but there is a difference in the light-shielding film on the gap-type photo sensor.

In FIG. 3, a light-shielding film 39 is provided on the manuscript distance adjusting layer 38. This light-shielding film reflects light on the manuscript surface and guides the light to the photosensor, so that a signal in a bright state is always read out. It is supposed to be. Further, FIG. 4 shows that a light shielding film 372 is provided between the passivation film 35 and the manuscript distance adjusting layer.
The light-shielding film prevents light reflected from the document surface from entering the photosensor. Therefore, in this pixel, the signal in the dark state is always read. FIG. 5 shows a structure in which there is no light-shielding film above the photo sensor, and the light reflection intensity of the original surface covered with the sensor upper surface can be read.

A method of manufacturing this sensor will be described with reference to FIG.
Here, description will be given using the pixels in the bright level reference row. First, as shown in FIG. 6A, Cr is deposited on the translucent substrate 1 by, for example, a sputtering method, and patterned by a normal photo-etching method to form a gate electrode 311 of the pixel switch portion and a storage. A lower electrode 312 of the capacitor portion and a lower light-shielding film 313 of the photosensor were formed. Next in FIG.
As shown in (b), after the silicon nitride film 32, the amorphous silicon film (i layer) 33, and the n-type amorphous silicon film 34 containing a small amount of P are deposited by the CVD method, the pixel is formed by the photoetching method. The amorphous silicon film and the n-type amorphous silicon film containing a small amount of P were processed so as to remain in the switch portion and the photosensor portion. Next, as shown in FIG. 6C, the upper electrode 3
5, the film thickness of Cr is, for example, 0.9 by the sputtering method.
After depositing 1 nm and Al having a film thickness of 0.5 nm, they were processed by photoetching, and the n-type amorphous silicon film 34 was removed using this as a mask. Next, as shown in FIG. 6D, the passivation film 36, for example, a silicon nitride film having a film thickness of 1 μm is deposited by a CVD method, and then an Al film having a film thickness of 1 μm is deposited as a light-shielding film. A light shielding film 371 on the upper part of the portion was formed. A light shielding film 372 was simultaneously formed on the dark level reference portion of FIG. 4 above the photo sensor portion. Next, as shown in FIG. 6E, as the inter-original distance adjusting layer 38, for example, glass resin having a film thickness of 15 μm is used.
Then, after coating Al and depositing Al to a film thickness of 2 μm, the light shielding film 39 is left on the photosensor in the bright level reference portion shown in FIG. With the manufacturing method described above, the structures of the two-dimensional sensor substrate and the main part of the sensor shown in FIGS. 3, 4, and 5 could be constructed.

Next, a system for reading two-dimensional information using this sensor substrate will be described with reference to FIG. The figure is a block diagram of the system. The sensor board is driven by a controller, an address control circuit, and a driver. The read signal is amplified by a preamplifier, then passed through a clamp circuit that determines the zero level (for example, black signal level) of the signal, and then passed through the amplifier circuit again, and an A / D converter for binarizing the signal. After passing through,
Save the data in a memory that stores the signal. After that, the controller reads the signal from the memory as needed and outputs the signal to a display or a printer. Figure 2 here
The usage of the data from the light level reference line and the dark level reference line shown in is explained. The controller monitors the address control circuit and controls the amplification factor of the preamplifier using the bright level signal when reading the bright level signal so that the amplification factor is maximized with the bright level signal. In addition, a dark level signal is extracted in the same manner, and the offset of the preamplifier is controlled using this signal so that the offset voltage becomes zero volt at the time of the dark level signal. In this embodiment, the controller drives the amplifier control circuit, but it is also possible to operate the amplifier control circuit by a signal from the address control circuit.

In the two-dimensional image reading system constructed as described above, the amplification factor of the preamplifier is always optimally controlled and the offset is always optimally controlled in accordance with the intensity of the light used, so that good reproduction is achieved. I was able to get the image.
The sensor substrate in the two-dimensional image reading system according to the present invention was set so as to cover the document surface, and the reading operation by room light was tried. As a result, it was possible to obtain a good reproduced image even though the light source had a large shading.

<Embodiment 2> A second embodiment of the present invention will be described with reference to the sectional view of an image reading pixel shown in FIG. The structure of the sensor substrate is similar to that of the previous embodiment, but here, the photosensor gate electrode 31 is used instead of the lower light-shielding film of the photosensor.
Configured as 4. In the previous example, the lower light-shielding film 313 was in a floating state, but the gate electrode 314 has a wiring structure in which a driving voltage can be applied. That is, the photosensor may have any structure from the point of the present invention. PGMA (polyglycidyl methacrylate) was applied to the inter-original distance adjusting layer 38 with a film thickness of 13 μm, and a silicon nitride film with a film thickness of 0.5 μm was deposited as the overcoat layer 40 by the CVD method. These films are also transparent in the visible light range and are suitable for contact sensors. A cross-linking agent (eg, tetrahydroxybenzophenone) was added to the PGMA to help it thermally cross-link with 0.1
A similar composition could be obtained with the addition of wt%. This sensor substrate also has a light / dark level reference row as in FIG.

FIG. 9 shows a system configuration method. Here, the clamp level is controlled by the data from the dark level reference row so that the clamp level takes the minimum value in the dark level data. By doing so, the black signal level was always fixed to the optimum value, and a good reproduced image could be obtained.

<Embodiment 3> Still another embodiment of the present invention will be described with reference to FIG. The sensor substrate and the light / dark level reference line are the same as in the previous example, and the system configuration is shown in FIG. Here, the brightness level signal and the image reading signal are stored in the memory, and when the image is reproduced, by the controller,
The image was reproduced for each pixel by calculating the image reading signal for each pixel from the values of the light level and the dark level. As a result, even if the same original was read while changing the light intensity, it was possible to obtain good images with the same reproduced images.

<Embodiment 4> Another embodiment of the present invention is shown in FIG.
Will be explained. In this embodiment, the light / dark level signal is converted to A / D.
After conversion, it is stored in the memory, and the image reading signal is passed through the preamplifier and then input into the amplifier again. At this time, after the light-dark level signal stored in the memory was D / A converted, the amplifier control circuit was operated using this signal to control the amplifier. The light / dark level reference line is provided as a line. Therefore,
In order to process the image signal with the amplifier, the amplifier process was performed while associating the light-dark level signal with the image signal for each column. As a result, the original image can be reproduced faithfully even when the intensity of the light source changes in the row direction.

In the present embodiment, while correcting the shading in the row direction, it was always possible to control the amplification factor and the offset suitable for the capability of the amplifier. In the same manner, the same effect was confirmed when the light and dark level signals were taken out in the first and second columns. That is, it was possible to correct the shading in the column direction by performing the reading operation at least twice and extracting the light / dark level signal from the first signal to control the amplifier at the second signal reading. The two methods could be combined to correct row and column shading. Here, the reading operation needs to be performed a plurality of times, but it is not necessary to replace the black-and-white reference document and the reading document, and the system repeatedly executes them as needed, so that it is possible to perform the operation for a very short time (for example, with no human intervention). Within 1 second), it is possible to read the light / dark level signal and the image signal, and
A good image could be read by performing the reading operation once.

[0029]

According to the present invention, it is possible to obtain a two-dimensional image sensor which can always read a good image even when the intensity of a light source beam changes and the background of an original has a density distribution. I was able to do it. That is, (1) in the document reading operation, the intensity data (bright level signal) of the light source beam was obtained, and shading correction by this signal and the amplifier for amplifying the image signal could always be controlled to an appropriate amplification factor. (2) The amplifier that amplifies the image signal can always be controlled to an appropriate amplification factor regardless of the background density of the document. (3) The offset of the amplifier that amplifies the image signal can always be controlled to a proper state regardless of the background density of the original. (4) After reading the original, even if the read data is data including shading of the light source, the reproduced image was properly corrected and a good image could be obtained. (5) It is possible to obtain the data (black level signal) when there is no light source ray by one reading operation for reading the original, and control the black level of the signal processing circuit to be always an appropriate value by this data. did it.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration according to the present invention.

FIG. 2 is an explanatory view showing an embodiment of the present invention.

FIG. 3 is a sectional view of a first step showing the first embodiment of the present invention.

FIG. 4 is a sectional view of a second step showing the first embodiment of the present invention.

FIG. 5 is a sectional view of a third step showing the first embodiment of the present invention.

FIG. 6 is a process drawing showing the first embodiment of the present invention.

FIG. 7 is a block diagram showing a first embodiment of the present invention.

FIG. 8 is a sectional view showing a second embodiment of the present invention.

FIG. 9 is a block diagram showing a second embodiment of the present invention.

FIG. 10 is a block diagram showing a third embodiment of the present invention.

FIG. 11 is a block diagram showing a fourth embodiment of the present invention.

[Explanation of symbols]

1 ... Substrate, 311 ... Gate electrode, 312 ... Lower electrode, 3
13 ... Lower light-shielding film, 32 ... Silicon nitride film, 33 ... Amorphous silicon film, 34 ... N-type amorphous silicon film, 35 ... Upper electrode, 36 ... Passivation film, 371 ... Light-shielding film,
38 ... Manuscript distance adjusting layer, 39 ... Light-shielding film.

Claims (8)

[Claims] 1. A contact type two-dimensional image sensor having a vertical scanning circuit, a horizontal scanning circuit, a signal reading circuit, and an image reading section in which pixels for reading image information in close contact with a document are two-dimensionally arranged. At least one side of the outer peripheral portion of the sensor substrate is provided with a light shielding film on the document surface as a structure of the optical sensor, and a pixel row for reading a light level signal by reflecting light from the sensor substrate side by the light shielding film is provided. A contact type two-dimensional image sensor characterized by being arranged. 2. A contact type two-dimensional image sensor having a vertical scanning circuit, a horizontal scanning circuit, a signal reading circuit, and an image reading section in which pixels for reading image information in close contact with a document are two-dimensionally arranged. A contact type two-dimensional image characterized in that a light-shielding film is provided in the vicinity of a photoelectric conversion element as a structure of an optical sensor on at least one side of an outer peripheral portion of a sensor substrate and a pixel row for reading a dark level signal is arranged. Sensor. 3. The light shielding structure according to claim 1, wherein the light sensor is provided with the light shielding film as a structure of the light sensor, and the light shielding is provided near a pixel column for reading the bright level signal or near a photoelectric conversion element. In a contact type two-dimensional image sensor having a film and a pixel row for reading a dark level signal, at least one layer of the transparent insulating film above or below the light shielding film is an organic resin or glass resin having an epoxy group. Contact type two-dimensional image sensor. 4. The light level signal obtained from a pixel column having the light shielding film on the document surface for reading a light level, or the dark level signal having the light shielding film near a photoelectric conversion element according to claim 1. A contact type two-dimensional image sensor that controls an amplifier that amplifies a photosensor output signal according to a dark level signal obtained from a pixel column for reading out. 5. The video signal processing circuit according to claim 2, wherein the light-shielding film is provided in the vicinity of the photoelectric conversion element, and a dark level signal obtained from a pixel column for reading a dark level signal is used to output an optical sensor output signal. Contact type two-dimensional image sensor that controls the level of the clamp circuit. 6. The pixel row according to claim 1 or 2, wherein the light-shielding film is provided on the surface of the original, and a pixel row for reading a light level, and the pixel row including the light-shielding film near the photoelectric conversion element for reading a dark level signal. After passing an output signal of a two-dimensional image sensor equipped with an amplifier and an A / D converter, the image data is stored in a memory for recording image information together with a light level signal and a dark level signal, and the image data is output. For this purpose, a contact type two-dimensional image sensor that outputs after processing image data using light level and dark level signals. 7. The pixel column according to claim 1, wherein the light shielding film is provided on the surface of the original, and a light level is read out; and the pixel column having the light shielding film near the photoelectric conversion element and reading a dark level signal is provided. A contact type two-dimensional image sensor having an output signal of the two-dimensional image sensor, an image signal stored in a memory for recording image information after passing through an amplifier and an A / D converter, and then outputting the image data. The light level and dark level signals of are stored in separate memories, and the data in this memory are used to control the amplification factor and offset of the amplifier that amplifies the output signal of the two-dimensional image sensor. Sensor. 8. A two-dimensional image reading apparatus characterized in that a two-dimensional sensor is placed on the surface of an original, room light from the back of the two-dimensional sensor is used as an incident light source for the sensor, and light reflected on the original surface is photoelectrically converted.