JPH02148866A - Image sensor - Google Patents

Abstract

PURPOSE:To read the image data of a source document accurately by providing a space filter element comprising a plurality of optoelectronic transducer elements which are aligned one- dimensionally in the direction perpendicular to the aligning direction of optoelectronic transducers for reading images on a board. CONSTITUTION:A non-contact type space filter part 3 which is used for detecting the relative moving distance with respect to a source document is provided in adjacent to an image reading sensor part 2. Therefore, the distance can be detected accurately regardless of the slip between the source documents, conditions for the source document and the like. Thus the image can be read accurately. Optoelectronic transducers 14 constituting the space filter part 3 are essentially the same as optoelectronic transducer elements 8 constituting the image reading sensor part 2. Both elements can be formed by the same process. Therefore, the production can be made easy. Since it is not necessary to assemble mechanical elements, the compact configuration of the entire sensor body can be realized.

Description

[Detailed description of the invention] [Object of the invention] (Industrial application field) The present invention relates to an image sensor.

(Prior Art) Conventionally, as a sensor for reading an image of a document or the like as a grayscale signal, an image sensor is known in which a plurality of image reading photoelectric conversion elements are arranged in one dimension. When actually reading an image of a document, etc. using such an image sensor, the image is scanned in the main scanning direction (the direction in which the photoelectric conversion elements for image reading are arranged) and is read as a grayscale signal. The reading operation in the main scanning direction and the sub-scanning are performed so that each time the operation is completed, the original or the sensor is moved relatively in the sub-scanning direction (a direction perpendicular to the arrangement direction of the photoelectric conversion elements for image reading) to read the next image. A method is adopted in which the images are sequentially read by repeating movement in the direction.

By the way, recently, a handy type image sensor has appeared that can be easily carried and read a desired image. This handy type image sensor is configured so that an image can be read by simply holding the sensor in the hand and moving it along the top surface of a document or the like. In other words, this type of image sensor has a distance detection system adjacent to the sensor body that detects the moving distance in the sub-scanning direction, and each time the distance detecting system detects a certain moving distance, it detects the moving distance in the main scanning direction. I'm trying to get it to scan.

The distance detection system usually consists of a roller that comes into contact with the original and rotates when driven by the original, and a rotary encoder that transmits the rotation of this roller via a belt or the like. A moving distance signal is obtained from a rotary encoder.

However, the image sensor in which the distance detection system having the above configuration is provided adjacent to the sensor body has the following problems.

That is, in the conventional image sensor, input to the distance detection system is obtained from a roller that rotates in contact with the document. However, the friction between the roller and the document is not always maintained above a certain level.

In particular, since the sensor is moved by hand, depending on the force of the movement, the roller may not come into contact with the document or may slip. Slip also occurs depending on the surface condition of the document. When such slipping occurs, accurate distance detection becomes impossible, and as a result, accurate reading of images becomes difficult. Furthermore, conventional image sensors incorporate a roller, a rotary encoder for converting the rotation of the roller into a relative movement distance, and a belt for transmitting the rotation of the roller to the rotary encoder.
There was also the problem that the sensor as a whole became larger.

(Problems to be Solved by the Invention) As mentioned above, conventional image sensors that incorporate a distance detection system are not only inherently difficult to read images accurately, but also are constructed using mechanical elements. Since it incorporates a distance detection system, there is a problem that the entire sensor becomes complicated and large.

Therefore, the present invention provides an image sensor that is equipped with a function that can detect the relative movement distance between the document and the document without contacting the document, and thereby can accurately read the image information of the document and can reduce the overall size. is intended to provide.

[Configuration of the Invention (Means for Solving the Problems) In order to solve the above problems, the present invention provides an image sensor in which a plurality of photoelectric conversion elements for image reading are arranged one-dimensionally on a substrate. It is equipped with a spatial filter element made up of a plurality of photoelectric conversion elements arranged one-dimensionally on the substrate in a direction perpendicular to the arrangement direction of the image reading photoelectric conversion elements.

Note that the photoelectric conversion element constituting the image reading photoelectric conversion element and the spatial filter element is composed of individual electrodes formed on a substrate, a photoconductive film formed on these individual electrodes, and a photoelectric conversion element constituting the image reading photoelectric conversion element and the spatial filter element. It can be configured with a transparent electrode formed on a conductive film.

Furthermore, individual electrodes of the photoelectric conversion element constituting the spatial filter element are configured with a first electrode group and a second electrode group,
The first electrode group and the second electrode group can also be arranged so as to mesh without contact.

(Operation) The spatial filter element can be used as a speed detection element that functions in a non-contact manner. The distance traveled can be detected by electrically processing the output. Therefore, it is possible to construct a distance detection system without requiring any mechanical elements. In this way, it is possible to detect the distance traveled without contacting the document, so unlike a combination of mechanical elements, it is possible to accurately detect the distance traveled, and as a result,
It becomes possible to read images accurately. Further, the photoelectric conversion element constituting the spatial filter element is essentially the same as the photoelectric conversion element for image reading, and the pixel elements can be formed in the same process during manufacturing.

Therefore, not only can manufacturing be simplified, but these elements do not require a large space, making it possible to downsize the entire sensor.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a plan view of the main parts of an image sensor according to an embodiment of the present invention.

The main parts are roughly divided into a rectangular substrate 1 made of an insulating material such as glass, an image reading sensor section 2 provided on the substrate 1, and a spatial filter section 3 also provided on the substrate 1. It is made up of.

The image reading sensor section 2 has a total of 1728 individual electrodes 4 arranged linearly on the substrate 1 in the longitudinal direction of the substrate 1 at a ratio of 8 electrodes per 1 m 11, and is connected to each of these individual electrodes 4. a photoconductive film 6 provided so as to integrally cover a portion of the upper surface of each lead-out conductor 5 and the upper surface of each individual electrode 4; and a transparent film 6 provided on the upper surface of this photoconductive film 6. It is composed of an electrode 7. That is, as shown in FIGS. 2(a) and 2(c), this image reading sensor unit 2 includes a photoelectric conversion element 8 composed of a transparent electrode 7, a photoconductive film 6, and an individual electrode 4. 1728 pieces are arranged in a straight line at a rate of 8 pieces per m+s, making it possible to read an A4 size sheet. Each lead conductor 5 is connected to a terminal 9 provided on the side edge of the substrate 1, respectively. Further, the transparent electrode 7 is connected to the terminal 11 via the lead conductor 10. It is.

On the other hand, the spatial filter section 3 has a plurality of strip-shaped electrodes 12 arranged at a constant pitch in the arrangement direction of the photoelectric conversion elements 8, that is, in the transverse direction of the substrate 1, and every other electrode 12 is commonly connected. The lead-out conductors 13a and 13b, and these lead-out conductors 13a.

The photoconductive film 6 described above is provided so as to cover a part of the upper surface of the electrode 13b and the upper surface of the electrode 12, and the transparent electrode 7 described above is provided on the upper surface of the photoconductive film 6. ing. That is, as shown in FIGS. 2(a) and 2(b), this spatial filter section 3 converts a photoelectric conversion element 14 composed of a transparent electrode 7, a photoconductive film 6, and a strip-shaped electrode 12 into a photoelectric conversion element. A plurality of photoelectric conversion elements 8 are arranged in a direction perpendicular to the arrangement direction of the photoelectric conversion elements 8, and every other photoelectric conversion element 8 is commonly connected by lead conductors 1a and 13b. The lead-out conductors 13a and 13b are terminals 15a provided on the side edges of the substrate 1.

15b.

Here, how to make the image reading sensor section 2 and the spatial filter section 3 will be briefly explained.

First, the individual electrodes 4 and lead-out conductors 5 of the image reading sensor section 2 and the electrodes 12 and lead-out conductors 13a, 13b of the spatial filter part 3 are made of nickel, chromium, aluminum, titanium, etc. formed by vapor deposition on the substrate 1. It is formed by etching a metal layer.

Next, the substrate 1 is placed in a plasma CVD apparatus. Then, by generating glow discharge in silane gas, an amorphous silicon semiconductor thin film such as an amorphous silicon film is formed on the heated substrate 1, and this thin film is used as a photoconductive film 6. In amorphous silicon, unbonded dangling bonds are compensated by hydrogen atoms generated by decomposition of silane, and the localized levels in the band gap are significantly reduced, so that gas containing impurity elements when discharged. If mixed with , it becomes an n-type or n-type semiconductor. Therefore, for example, in silane gas containing diborane at a predetermined concentration, n-type amorphous 9
932 layers, then carving an i-type amorphous silicon layer of a predetermined thickness that does not contain impurities, and finally forming an n-type amorphous silicon in silane gas containing a predetermined concentration of phosphine. An amorphous silicon semiconductor film having a PiN structure is formed by this method, and this may be used as the photoconductive film 6.

Next, the transparent electrode 7 serving as a common electrode for the image reading sensor section 2 and the spatial filter section 3 is connected to the individual electrode 4.
The photoconductive film 6 is formed on the photoconductive film 6 in the same manner as the electrode 12. In this example, the transparent electrode 7 is formed of JTO (an oxide of indium and tin).

Note that in order to prevent light from the image from hitting the photoconductive film 6 on the lead-out conductors 5.13a and 13b, a light shielding film may be formed on the transparent electrode 7 at a position facing these conductors.

Each terminal 9 of the image reading sensor section 2 and the terminals 15a, 15b of the spatial filter section 3 are connected to an image signal reading circuit 21 shown in FIG.

This image signal readout circuit 21 includes a readout control circuit 22 that sequentially reads out the output of each photoelectric conversion element 8 of the image reading sensor section 2 in time series, and an output of the spatial filter section 3 to control the relative movement of the document. It is comprised of a measurement control circuit 23 that detects the distance and provides a readout start signal to the readout control circuit 22 every time the moving distance reaches a certain value.

The read control circuit 22 is configured as follows. That is, one end side of an analog switch 24 is connected to each terminal 9 of the image reading sensor unit 2 in a one-to-one relationship, and the other end side of these analog switches 24 is commonly connected to an amplifier 25 having a current-voltage conversion function. It is connected to the output terminal 26 via. On the other hand, a clock generating section 27 is provided, and the clock signal CK outputted from the clock generating section 27 is applied to a counter 28 on one side and to one input terminal of an AND gate 29 on the other side.

When the counter 28 receives an output pulse PS from the measurement control circuit 23, which will be described later, it enters a clear state, and starts counting the clock signal CK from this clearing point. In this example, the counter 28 sends out the output pulse RP when it counts 1728 pulses. This output pulse RP is RS
It is given as a reset signal for the S flip flow circuit 30.

The flip-flop circuit 30 is put into a set state by the output pulse PS, and put into a reset state by the output pulse RP. The set output of the flip-flop circuit 30 is applied to the other input terminal of the AND gate 29, and the output of the AND gate 29 is applied to the shift register 31 as a shift clock. In this example, the shift register 31 has near 28 bits, and is equipped with a drive system that turns on the analog switch 24 corresponding to each bit output. Then, when the output pulse PS is applied, the bit in the first stage is held at a logical value of "1", and every time the shift clock is applied.

The bits in the rows are sequentially switched to "1".

On the other hand, the total 6J1 control circuit 23 is configured as follows. That is, the terminals 15a and 15b of the spatial filter section 3
The current signals obtained through the respective current-voltage converters 32.
33, it is converted into a voltage signal. Then, both pressure signals are introduced into a moving distance detection circuit 35 via a differential amplifier 34. The moving distance detection circuit 35 detects the moving distance between the image sensor and the document in the sub-scanning direction by means described later.
It is configured to send out an output pulse PS as a readout start signal every time this moving distance reaches a certain value (for example, 0.1 mm).

Although not shown, this image sensor includes:
An illumination system for illuminating the document surface and a lens for focusing an image on the document surface onto the light receiving surfaces of the image reading sensor section 2 and the spatial filter section 3 are provided.

Next, the operation of the image sensor configured as described above will be explained.

First, the operations of the spatial filter section 3 and the measurement control circuit 23 will be explained. When the original moves relatively in the arrangement direction of the plurality of photoelectric conversion elements 14 constituting the spatial filter section 3, signals corresponding to the shading of the original surface are output from the terminals 15a and 15b. This irregular gray level signal includes various frequency components, including a frequency component that fluctuates in accordance with the relative movement speed. This frequency is f
1 The magnification of the optical system is m, and the pitch of the photoelectric conversion element 14 is p(
(see FIG. 2(b)), the relative moving speed V is obtained as V-f-p/m (1). The differential amplifier 34 of the measurement control circuit 23 is
A signal with a frequency component corresponding to the relative movement speed is extracted. This extracted signal is introduced into the moving distance detection circuit 35. The moving distance detection circuit 35 first detects the frequency f
is specified, and the moving speed V is calculated based on equation (1).

Then, calculate the travel distance by integrating this speed V over time,
An output pulse PS is sent out every time this moving distance reaches 0.1 mm. Therefore, one output pulse PS is sent from the measurement control circuit 23 every time the image sensor moves 0.1 mm in the sub-scanning direction with respect to the original.

On the other hand, when the readout control circuit 22 receives the output pulse PS, the counter 28 is cleared, the flip-flop circuit 30 is set, and the first stage bit of the shift register 31 is held at "1" data. . As a result, the AND gate 29 opens and the shift register 31
A shift pulse is given to As a result of this shift operation, the analog switches 24 are sequentially turned on, and as a result, 1728 grayscale signals read by the image reading sensor unit 2 are sent out from the output terminal 26 in time series.

Then, when the next output pulse PS is applied, the above operation is performed again, and the function as an image sensor is exhibited well.

In this way, the non-contact spatial filter section 3 is provided adjacent to the image reading sensor section 2 for detecting the distance of movement relative to the original. Therefore, distance detection can be performed accurately without being affected by slippage between the document and the document, conditions for the document, etc., and images can be accurately read. Furthermore, the photoelectric conversion element 14 that constitutes the spatial filter section 3 is essentially the same as the photoelectric conversion element 8 that constitutes the image reading sensor section 2, and both can be formed in the same process. Can be done. Therefore, manufacturing can also be facilitated. Furthermore, since there is no need to incorporate mechanical elements, the entire sensor can be made smaller.

FIG. 4 is a plan view of the main parts of an image sensor according to another embodiment of the present invention.

This main part differs from the main part shown in FIG. 1 in the configuration of the spatial filter section 3a. That is, in the case shown in FIG. 1, every other electrode 12 is connected to a lead conductor 13a,
13b, but in the example shown in FIG. 4, the electrodes 12 are connected to independent terminals 42 via independent lead-out conductors 41. That is, in the embodiment, the photoelectric conversion elements 14 constituting the spatial filter section 3a are made independent.

FIG. 5 is a diagram showing an image signal readout circuit 21a to which the main parts configured as shown in FIG. 4 are connected. This circuit 21a is different from the circuit shown in FIG.
This is in the configuration of the total n1 control circuit 23a. That is, the measurement control circuit 23a uses the odd numbered elements of each photoelectric conversion element 14 constituting the spatial filter section 3a as one block, and the even numbered elements as one block. The terminals 42 of the odd-numbered elements are connected to the input terminals of the current-voltage converter 32 via analog switches 43, respectively. Furthermore, even-numbered terminals 42 are each connected to the input end of the current-voltage converter 33 via an analog switch 44. The analog switches 43 and 44 are alternately turned ON by shift registers 45 and 46 driven by a clock signal. Note that 46 and 47 in the figure indicate an integrator.

Even with this configuration, the same effects as in the embodiment described above can be obtained.

[Effects of the Invention] According to the present invention, a sensor for reading pixel information of an image and a spatial filter element for detecting irregular brightness information on the image are disposed on the substrate, so that the image information is The relative movement distance signal necessary for reading can be obtained from an optical signal that is not affected by scanning conditions or the material of the document. Therefore, it is possible to read images with high precision and is also compact.

Light weight can be realized.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway plan view showing the main parts of an image sensor according to an embodiment of the present invention, FIG. 2(a) is a sectional view taken along line A-A in FIG. (b) is B in Figure 1.
- A sectional view taken along the line B, FIG. 2(c) is a sectional view taken along the line C-C in FIG. 1, and FIG. 3 is a configuration diagram of the image signal readout control circuit.
FIG. 4 is a partially cutaway plan view showing the main part of an image sensor according to another embodiment of the present invention, and FIG. 5 is a configuration diagram of an image signal readout circuit connected to the same end. DESCRIPTION OF SYMBOLS 1... Substrate made of insulating material, 2a... Image reading sensor section, 3.3a... Spatial filter section, 8°14...
Photoelectric conversion element, 21.21a... Image signal readout circuit, 22... Readout control circuit, 23.232... Measurement control circuit.

Claims (3)

[Claims] (1) In an image sensor in which a plurality of photoelectric conversion elements for image reading are arranged one-dimensionally on a substrate, the photoelectric conversion elements for image reading are arranged one-dimensionally on the substrate in a direction perpendicular to the arrangement direction of the photoelectric conversion elements for image reading. An image sensor comprising a spatial filter element made up of a plurality of photoelectric conversion elements. (2) The photoelectric conversion element constituting the image reading photoelectric conversion element and the spatial filter element includes individual electrodes formed on the substrate, a photoconductive film formed on these electrodes, and a photoconductive film formed on these electrodes. The image sensor according to claim 1, comprising a transparent electrode formed on a conductive film. (3) The individual electrodes of the photoelectric conversion element constituting the spatial filter element are composed of a first electrode group and a second electrode group, and the first electrode group and the second electrode group are non-contact. 3. The image sensor according to claim 2, wherein the image sensor is arranged so as to engage with the contact.