JPH11234473A - Photoelectric converter, close contact image sensor and image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a photoelectric converter that can realize a read speed corresponding to a selected resolution and is suitable for a high speed close contact image sensor by selecting the number of light receiving elements of the photoelectric converter to a multiple of 2N, where a low resolution is set at 1/N of a high resolution. SOLUTION: In a high resolution mode, photoelectric converters 1, 1' have 344-bit signals respectively, and shift register signal 9-1, 9'-1 of the 341st bit are used for next chip start signals. In a low resolution mode, a 2-pixel sum signal is 1-bit, so that the photoelectric converters 1, 1' have equivalent 177-bit signals. Thus, 377-th bit shift register signals 9-2, 9'-2 are used for next chip start signals. In this case, the number of light receiving elements of the photoelectric converters 1, 1' is a multiple of 2N, where a low resolution is set at 1/N of a high resolution. Thus, continuity of pixel signals is maintained even when a different resolution is selected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact type image sensor in which a plurality of photoelectric conversion devices each having a one-dimensional photoelectric conversion element and a driving circuit for driving the one-dimensional photoelectric conversion element are mounted, and a driving method thereof. The present invention relates to a contact image sensor having a resolution switching function, a photoelectric conversion device used for a driving method of the contact image sensor, and an image reading device for reading a two-dimensional image such as an image scanner, a facsimile, and an electronic copying machine. is there.

[0002]

2. Description of the Related Art In recent years, in the field of information processing systems, as a one-dimensional image reading apparatus, a plurality of semiconductor optical sensor chips are multi-mounted on a scale-based line sensor using a conventional optical system. The development of close contact type image sensors is being actively pursued.

(Prior Art 1) For example, Japanese Patent Application Laid-Open No. 5-227
Japanese Patent Publication No. 362 proposes a contact-type image sensor in which a new control terminal for controlling the resolution is provided and the user can switch the resolution in accordance with the use conditions.

FIG. 7 is a circuit diagram of an integrated circuit for a contact type image sensor proposed in the publication. In this conventional technique, a control terminal (125) is provided on an image sensor chip, and a user switches between a high resolution mode and a low resolution mode by inputting a high-level or low-level signal to the terminal. I have. Referring briefly to FIG. 7, the start pulse S
I and the clock pulse CLK are transferred to the shift register group 10
4 When the shift register 104a is activated by the start pulse SI, its output becomes NOR gate 1
The signal is input to the channel select switch 103a through the gate 21a and the AND gate 120a.
Take out to a. Other shift registers 104b to 104f
Are sequentially activated, and each photocell 101b to 101l
Are output to the signals 107a and 107b.

Here, the control signal input terminal 125
When the control signal "H" is input to the analog switch 110, the analog switches 110a, 110b, 122a, and 122b are switched, and an image signal is obtained at the image output terminal 111 at a reading density of 16 dots / mm. When the control signal “L” is input to the control signal input terminal 125, the analog switch 110a is always on, and the image output terminal 111 is connected to the photocells 101a to 101a.
An image signal can be obtained at a reading density of 8 dots / mm, which is half of 1 l. That is, the photocell 1 on the sensor IC
All of 01a to 101l are always in operation, but when extracting output image signals to the outside, a part of the output image signals can be thinned out and output. for that reason,
The voltage level of the image signal is always constant, and the configuration of the image processing circuit at the subsequent stage can be handled by a conventional one.

(Prior Art 2) On the other hand, in response to a demand for high speed, for example, Japanese Patent Application Laid-Open No. 2-210950 proposes an image sensor chip having a means for delaying a start signal and a contact image sensor. Therefore, high-speed reading is realized by starting up the constant current circuit before reading the sensor signal. That is, in an image sensor chip used in a multi-chip type photoelectric conversion device configured by arranging a plurality of image sensor chips having light receiving elements and a photoelectric conversion device using the same, an optical signal reading operation by the light receiving element is performed. A delay means for delaying a start signal; and a constant current in an amplifier circuit for amplifying the optical signal read signal, the signal having a signal used as a start signal for the image sensor chip to be discussed before the optical signal read operation is completed. Circuit
By a start signal indicating the start of delay of the delay means,
It is characterized by starting up.

Japanese Patent Application Laid-Open No. 2-210949 discloses a one-chip configuration used in the above-mentioned Japanese Patent Application Laid-Open No. 2-210950, in which an internal clock Φ1 synchronized with a high level of a clock signal and a low level of the clock signal. An image sensor chip for driving a shift register using an internal clock φ2 synchronized with a level and a contact image sensor have been proposed, thereby realizing high-speed reading with a duty of 100%.

FIG. 8 shows a conventional example as disclosed in Japanese Patent Laid-Open No.
FIG. 10 shows an equivalent circuit diagram of an image sensor chip assumed from the contents described in JP 10949 and JP-A-2-210950.

In FIG. 8, photoelectric conversion devices (1, 1 ',
1 ″) are multi-mounted, and a clock (CLK) for driving each photoelectric conversion device and a start pulse (SP)
Are connected in common. In addition, each photoelectric conversion device (1,
1 ', 1 ") are N-bit delay means (N-bit pre-shift registers 2, 2', 2"), K-bit shift registers (3, 3 ', 3 "), and K-bit light receiving element arrays (4, 4'). , 4 ″), a timing generation circuit (5, 5 ′,
5 ") and a signal output amplifier (6, 6 ', 6").

The next chip start signal (9, 9 ',
9 ") is a signal which is N bits (K-N bits) before the bit of each photoelectric conversion device ends reading (K-N bits) from the N-bit part before the last register of the shift registers 3, 3 ', 3". It is output as a chip start signal.

A timing generator (5, 5) driven by a clock signal CLK and a start pulse signal SP.
5 ', 5 "), the pulses for driving the light receiving elements 4, 4', 4" and the driving pulses Φ1 (7, 7 ', 7 "), Φ2 for driving the shift registers 3, 3', 3". (8,
8 ', 8 ") are generated. The start pulse signal SP is connected in common to each image sensor chip.
This is for synchronizing the operation start of each image sensor chip.

The signal output amplifiers 6, 6 ', 6 "
Image signals read out from the light receiving element arrays 4, 4 ', 4 "to one signal output line via a switch which is turned on / off by a shift signal of a shift register are amplified, and timing generation circuits 5, 5', 5" are amplified. Signal output Vout by the control signal. Note that the signal output amplifiers 6, 6 ',
A constant current circuit is provided in 6 ", and power supply starts simultaneously with the input of a start signal, and a steady amplification operation is enabled when an N-bit clock signal is input from the start signal.

FIG. 9 shows drive pulses .PHI.1 (7, 7 ', 7 ") and .PHI.2 (8, 8',
8 ″) is a timing chart.

FIG. 9 shows that the delay means 2 in FIG.
This is the timing when bits are set. Therefore, the shift registers 3, 3 ', 3 "start the operation of the first shift register with a delay of 4 bits from the start pulse signal SP.

Here, as shown in FIG. 9, the drive pulse .PHI.1 (7, 7 ', 7 ") of the shift register 3 is a pulse synchronized with the high level of CLK, and the drive pulse .PHI.2 (8, 8',
8 ″) is a pulse synchronized with the low level of CLK.
The signal output Vout is taken out in synchronization with Φ1 and Φ2. Therefore, when the first bit of the shift register 3 corresponds to Φ1, the odd bits are synchronized with Φ1, and the even bits are Φ2.
Synchronous signal output.

FIG. 1A shows the signal output of the photoelectric conversion device (1),
7C shows the signal output of the photoelectric conversion device (1 '), and FIG. 7E shows the signal output of the photoelectric conversion device (1 "), and the overall signal output Vout is as shown in the figure. The converter outputs a signal four bits before the last bit as a start signal (B, D) for the next photoelectric converter.

In this manner, a large original can be directly read as a multi-chip contact type image sensor, and the read rest time between chips and the difference in signal output level can be eliminated.

[0018]

However, in the resolution switching method of the contact type image sensor disclosed in the above-mentioned prior art 1, since the resolution is switched by skipping pixels, for example, the clock rate is reduced. In the same case, even if the resolution is halved, the reading time does not change whether the resolution is normal or half. If the light receiving elements are arranged at an optical resolution of 600 dpi and a resolution of 600 dpi is obtained in the high resolution mode and a resolution of 300 dpi is obtained in the low resolution mode, for example, when a reading speed of 6 msec / line is obtained at 600 dpi, even at 300 dpi 6msec /
The reading speed is line, and the reading speed does not change even if the resolution is lowered.

Therefore, using the same clock rate, 6
5 msec / line reading speed at 00 dpi,
There is a problem that it is not possible to realize a reading speed corresponding to the resolution, such as a reading speed of 3 msec / line at 300 dpi.

Further, since the odd-numbered bit and the even-numbered bit signal output lines are separated from each other, there is also a problem that the level difference between the even-numbered bit and the odd-numbered bit tends to occur.

Further, when the resolution switching disclosed in the prior art 1 is applied to the contact type image sensor disclosed in the prior art 2, when the resolution is switched, a discontinuous portion is formed at the joint of the photoelectric conversion device. A problem arises.

For example, in the prior art 2, if the number of bits of the pre-shift register is 10 bits, the first bit of the next photoelectric conversion device is output 10 bits after the output of the next chip start signal in the high resolution mode. Therefore, the signal at the joint of the photoelectric conversion device does not become discontinuous. However, in the low resolution mode, the signal output ends 5 bits after the next chip start signal is output. Until the bit is output, a discontinuity of 5 bits occurs at the joint of the photoelectric conversion device.

[Object of the Invention] An object of the present invention is to provide a high-speed contact image sensor capable of realizing a reading speed according to the resolution when switching the resolution, and a photoelectric conversion device suitable for the contact image sensor. Is to do.

[0024]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a light receiving element array in which a plurality of light receiving elements are arranged at a first resolution, and an odd-numbered light receiving element of the light receiving element array. Scanning means driven by a first shift register drive pulse for reading an element and a second shift register drive pulse for reading an even-numbered light-receiving element of the light-receiving element array; one of the first resolution and the first resolution; / N (N
And a resolution switching means for switching between the second resolution and the second resolution, which is a natural number), wherein the number of the plurality of light receiving elements is a multiple of 2N.

Also, the present invention provides a light receiving element array in which a plurality of light receiving elements are arranged at a first resolution, a first shift register driving pulse for reading out odd-numbered light receiving elements of the light receiving element array, and a light receiving element. Scanning means driven by a second shift register drive pulse for reading the even-numbered light receiving elements of the array; and a second resolution which is the first resolution and 1 / N (N is a natural number) of the first resolution. And a resolution switching means for switching between the two types of photoelectric conversion devices, wherein the number of light receiving elements of the photoelectric conversion devices is a multiple of 2N.

Further, according to the present invention, the plurality of light receiving elements are the first
, A first shift register driving pulse for reading out odd-numbered light receiving elements of the light receiving element array, and a second shift register driving pulse for reading out even numbered light receiving elements of the light receiving element array And a resolution switching means for switching between the first resolution and a second resolution that is 1 / N (N is a natural number) of the first resolution. The first light receiving element of the light receiving element array is read out by the first shift register driving pulse, and the last light receiving element is read out by the second shift register driving pulse.

Still further, according to the present invention, in an image sensor in which a plurality of photoelectric conversion devices including a plurality of light receiving elements are connected, a resolution selecting means for selecting a resolution and a selection in each of the photoelectric conversion devices by the resolution selecting means. Control means for changing a method of reading a signal from the light receiving element according to the determined resolution; and signal reading means for reading a signal from the light receiving element with a plurality of pulses. And the number of light receiving elements arranged is set such that the signal read out first from the signal reading means in each photoelectric conversion device is read out by the same pulse among the plurality of pulses.

Still further, the present invention provides a light receiving element array in which a plurality of light receiving elements are arranged at a first resolution, a first shift register driving pulse for reading out odd-numbered light receiving elements of the light receiving element array, and a light receiving element. Scanning means driven by a second shift register driving pulse for reading out the even-numbered light receiving elements of the element array; and a second resolution which is the first resolution and 1 / N of the first resolution (N is a natural number). An image scanner using a contact type image sensor configured by mounting a plurality of photoelectric conversion devices having a plurality of photoelectric conversion devices, and a facsimile, an electronic copying machine, and the like. The number of light receiving elements is a multiple of 2N, and the first resolution and the second
And a switch for switching the resolution.

[Operation] In the present invention, in a contact type image sensor mounted on a multi-chip, a means for selecting a start signal for starting a shift register of the next chip by a resolution switching signal is provided. Also, no discontinuous bit occurs at the joint of the photoelectric conversion device.

Further, the present invention provides four pixels (a, b, c,
d) is defined as one block. In the high resolution mode, the bits a and c are driven by the synchronous clock φ1 and the bits b and d are driven by the synchronous clock φ2 inverted to the synchronous clock φ1, and in the low resolution mode, the synchronous clock φ1 is used. a + b bits
Since the means for reading out the bits of c + d by the pixel addition with the synchronous clock Φ2 is provided, the reading speed according to the resolution can be realized even if the same clock rate is used.

[0031]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) FIG. 1 shows Embodiment 1 of the present invention.
2 is a circuit block diagram of a contact image sensor using a photoelectric conversion device in FIG. 2, FIG. 2 is a circuit block diagram of an 8-bit shift register and a light receiving element in FIG. 1, FIG. 4 is a timing chart showing the operation of FIG. Is an equivalent circuit diagram of a light receiving element for four pixels.

In FIG. 1, a plurality of photoelectric conversion devices 1 and 1 'are mounted to form a close contact type image sensor. Although FIG. 2 shows only two chips, in the present embodiment, for example, 15 chips are arranged in one row and multi-mounted to form a contact image sensor.

In FIG. 1, each photoelectric conversion device 1
1 ′ includes a clock (CL) for driving the photoelectric conversion device.
K), a start pulse (SP), a resolution switching signal (MODE), and a signal output Vout are commonly connected, and a read start signal SI of the line sensor is input to the original image sensor chip 1.

In this embodiment, when the MODE signal is at a high level, the high resolution mode (600 dp) is used.
i) When the MODE signal is at a low level, a resolution of a low resolution mode (300 dpi) can be obtained.

Further, each of the photoelectric conversion devices 1, 1 'of this embodiment is multi-mounted, and has N bits, for example, 4 bits.
a pre-shift register 2, 2 'having a bit delay, a shift register 3, 3', a light receiving element array 4, 4 'of K bits, for example, 344 bits, a timing generating circuit 5,
5 'and signal output amplifiers 6 and 6'. here,
The shift registers 3, 3 'are composed of a shift register block 11 for 4 bits.

The image signals received by the light receiving element arrays 4 and 4 'are read out to signal output lines via switches which are turned on / off by shift signals of the shift registers 3 and 3', and are output to signal output amplifiers. It is amplified at 6, 6 '. Then, switching is performed by the control signals of the timing generation circuits 5, 5 ', 5 "and output as a signal output Vout. A constant current circuit is provided in the signal output amplifiers 6, 6', and a start signal is provided. Power supply to the signal output amplifiers 6 and 6 'starts simultaneously with the input of the SP, and a steady amplification operation is enabled when an N-bit clock signal is input from the start signal.

The start signal switching means 1 converts a start signal (9-1, 9'-1) in the high resolution mode and a start signal (9-2, 9'-2) in the low resolution mode.
By selecting using 0, 10 ', the next chip start signal 9, 9' is obtained.

The next chip start signals 9 and 9 'are the signals N bits (K-N bits) before the end of reading of the bits of each photoelectric conversion device, and are the final registers of the shift registers 3 and 3'. Is output as a start signal of the next chip from the N-bit portion before the above.

The timing generation circuit 5 driven by the clock signal CLK and the start pulse signal SP,
5 ′, a pulse for driving the light receiving elements 4, 4 ′ and a driving pulse Φ1 for driving the shift registers 3, 3 ′
(7, 7 ') and Φ2 (8, 8') are generated. The start pulse signal SP is commonly connected to each image sensor chip to synchronize the operation start of each image sensor chip.

Next, FIG. 2 is a circuit block diagram of an 8-bit shift register and a light receiving element. The shift register is a shift register block 1 having 4 bits as one block.
The shift register block 11 is composed of 1-bit shift registers 12-1 to 12-
4. 1-bit shift registers 13-1 to 13 synchronized with Φ2
-4, and an analog switch S for switching a mode signal
11 to S17 and S21 to S27.

Further, the shift register block 11 uses the read pulse lines Φa1 to Φd2 and the light receiving elements a1 to d2.
And switch control terminals between the signal output lines (not shown).

FIG. 3 is an equivalent circuit for four pixels of the light receiving element in FIG. 2. Each of the light receiving elements a1 to d1
Photodiodes PDa to PDd serving as photoelectric conversion means, readout switches M1a to M1d, signal transfer switch M2
a to M2d, MOS source followers M3a to M3d, reset switches M4a to M4d for resetting the photoelectric conversion means, and a storage capacitor C for temporarily storing electric charges.
a to Cd.

Hereinafter, the operation of this embodiment will be described.

In each of the light receiving elements a1 to d1 shown in FIG. 3, optical carriers generated by photoelectric conversion by the photodiodes PDa to PDd are MOS source followers M3a to M3.
The charge-to-voltage conversion is performed at d, and all the pixels are collectively transferred to the storage capacitors Ca to Cd by the signal transfer pulse φT. Subsequently, the read pulse Φa sequentially becomes high from the shift register 11.
1 to Φd1 and sequentially read out switches M1a to M1
d is turned on, and the signal voltage is divided by the common signal line 14 and read.

In the present embodiment, the read pulses Φa1 to Φd1 are sequentially turned on in the high resolution mode, but in the low resolution mode, two adjacent bits, ie, Φa1 and Φb1 scanned from the shift register 11, are turned on simultaneously. Then, Φc1 and Φd1 are simultaneously turned on. Therefore, in the low resolution mode, the signal voltage can be made larger than that in the high resolution mode by the capacity division addition of two pixels. The above-described capacity division addition is disclosed in, for example, Japanese Patent Application Laid-Open No. 4-4682.

Next, the operation of the shift register unit will be described with reference to FIGS.

In FIG. 2, when the MODE signal is at a high level, S11, S21, S16, S17, S26,
The analog switch in S27 is turned off, while S
12, S13, S14, S15, S22, S23, S2
4. S25 is turned on. Therefore, a normal shift register operation without resolution switching is performed, and the read control pulses Φa1 to Φd2 for each light receiving element are sequentially turned on in time series. Although the output line of the image signal is not shown in FIG. 2, the light receiving charges of the respective light receiving elements a1 to d2 are output to the signal output line in synchronization with the successive highs by the control pulses Φa1 to Φd2. Is done.

Next, when the MODE signal is at the low level, S11, S21, S16, S17, S26, S27
Are turned on, while S12,
S13, S14, S15, S22, S23, S24, S
25 turns off. Therefore, the shift register 12-
When a shift pulse is input to the shift register 12, the shift register 12
From −1, Φa1 and Φb1 are output in synchronization with Φ1 and the signals of the light receiving elements a1 and b1 are simultaneously read. Subsequently, the shift pulse is input to the shift register 13-2 via the analog switch S11, Φc1 and Φd1 are output from the shift register 13-2 in synchronization with Φ2, and the signals of the light receiving elements c1 and d1 are simultaneously read. Also in the case of the low-resolution reading mode, the light receiving elements a1 and b
The added charges of the pair of light receiving elements are sequentially read out, such as 1, c1 and d1, a2 and b2, and c2 and d2.

At this time, the shift registers 13-1 and 12-2 do not operate because no shift pulse is input. Similarly, Φa2 and Φb2 are output from the shift register 12-3 in synchronization with Φ1, and the signals of the light receiving elements a2 and b2 are simultaneously read out.
4, Φc2 and Φd2 are output in synchronization with Φ2, and c2 and d
The signals of the two light receiving elements are simultaneously read.

FIG. 4 shows a timing chart of the above operation. In FIG. 4, a clock signal CLK and synchronizing signals Φ1 and Φ2 are commonly supplied to the high resolution mode and the low resolution mode, the start signal SR becomes high, and the image signal outputs of the high resolution mode and the low resolution mode are output. can get. From the figure, at the same clock rate,
It can be seen that in the low resolution mode, reading can be performed at twice the reading speed as in the high resolution mode.

Next, means for switching the next chip start signal will be described.

In FIG. 1, the pre-shift register 2,
Since 2 'has a delay of 4 bits, a signal 4 bits before must be output as a start signal of the next chip. By the pre-shift registers 2, 2 ', there is no need to adjust the time from the start signal SP, and after the reading of the photoelectric conversion device at the preceding stage is completed, continuous image signals without gaps can be obtained according to the same timing. Therefore,
In the case of the high resolution mode, since the photoelectric conversion devices 1 and 1 'each have a signal of 344 bits, the shift register signal 9-1 and 9'-1 of the 341 bit is used as the next chip start signal.

In the low-resolution mode, the two-pixel addition signal has one bit, and therefore, the photoelectric conversion devices 1 and 1 '.
Has a signal of 177 bits equivalently. Therefore, the shift register signals 9-2 and 9'-2 of the 337th bit in terms of the light receiving element are used as the next chip start signal. That is, by providing the start signal switching means for switching the next chip start signal, it is possible to maintain the continuity of the pixel signal at the joint of the photoelectric conversion device even when the resolution is switched.

In the above embodiment, the number of bits of the photoelectric conversion device is 344 bits, but any number of bits may be used as long as the number of bits is a multiple of four.

The resolution is not limited to the case where the [high resolution mode / low resolution mode] is [600 dpi / 300 dpi], but may be a resolution such as [400 dpi / 200 dpi].

Further, in the present embodiment, the case where the resolution ratio between the high resolution mode and the low resolution mode is twice is shown. For example, six pixels are one block, and the number of pixels of the photoelectric conversion device is a multiple of six. By doing so, [600 dpi / 200 dpi
It is easy to set the resolution ratio to three times as in the switching of [i].

Therefore, in this case, if the high resolution and 1 / N (N is a natural number) of the high resolution are defined as the low resolution, the number of the plurality of light receiving elements of each photoelectric conversion device is a multiple of 2N.

Focusing on the plurality of light receiving elements of each photoelectric conversion device, the first light receiving element of the light receiving element array is read by the odd-numbered shift register drive pulse, and the last light receiving element is the even number. , A continuous image signal without discontinuity in timing can be obtained.

The number of shift register drive pulses is two in the above embodiment, but is not limited to this. For example, by changing the configuration of the shift register, three pulses are used.
With one shift register driving pulse, it is also possible to add and read out three adjacent light receiving elements when low resolution is selected. That is, when driven by M shift register driving pulses, the resolution is 1 /
The number of light receiving elements may be a multiple of MN as long as it has a plurality of resolutions that change by N.

As an image scanner, a facsimile, or an electronic copier, a selection switch for selecting any one of a plurality of resolutions is provided, and a direction in which the contact type image sensor is read is set as a main scanning direction, and the direction is perpendicular to the main scanning direction. A two-dimensional reading signal is obtained by mechanically scanning the original in the sub-scanning direction also in the sub-scanning direction, and exposing the optical photosensitive member in accordance with the reading signal. Thus, the image can be transferred to the transfer target paper according to a plurality of resolutions, and the degree of functional freedom can be increased.

(Embodiment 2) FIG. 5 shows Embodiment 2 of the present invention.
FIG. 2 is a circuit block diagram of a contact image sensor using a photoelectric conversion device in FIG.

In the present embodiment, a terminal (MODE2) for controlling the resolution is added to the first embodiment, and a high resolution mode (1200 dpi), a medium resolution mode (600 dpi), and a low resolution mode (300 dpi) are added.
3 is capable of switching between three resolutions.
However, the number of resolutions in each mode is an example, and can be set arbitrarily according to the purpose.

In FIG. 5, each photoelectric conversion device 1,
Reference numeral 1 'denotes a pre-shift register 2, 2' having a 4-bit delay, shift registers 3, 3 ', a 688-bit light receiving element array 17, 17', a timing generation circuit 5,
5 'and signal output amplifiers 6 and 6'. here,
The shift registers 3, 3 'are composed of a shift register block 16 for 8 bits. Further, three types of start signals extracted from the shift register, namely, start signals 9-1 and 9'-1 in the high resolution mode, start signals 9-3 and 9'-3 in the middle resolution mode, and a low resolution signal The next chip start signals 9, 9 'are obtained by selecting the start signals 9-2, 9'-2 at the time using the start signal switching means 10, 10'.

FIG. 6 shows a specific circuit diagram of the start signal switching circuit 10. 1 from each of MODE1 and MODE2
A bit signal is input, and start signals 9-1 and 9'-1 in the high resolution mode, start signals 9-3 and 9'-3 in the middle resolution mode, and a start signal 9- in the low resolution mode.
2, 9'-2 are selected and output as start signals 9, 9 'for the next image chip. When MODE1 and MODE2 are [0,0], it is the blank mode and no output is made. It should be noted that such a selection switching circuit can be easily achieved by another circuit using a logic circuit, and a description thereof will be omitted.

In this embodiment, one pixel is one bit in the high resolution mode, two bits are one bit by adding two pixels in the middle resolution mode, and one bit is four bits in the low resolution mode by adding four pixels. Become. Accordingly, the shift register block 16 has one block of eight pixels, and can be configured in the same manner as in the first embodiment.

As shown in this embodiment, in the present invention, three or more resolution modes can be set, and a reading speed corresponding to each resolution can be realized. It is possible to prevent signal discontinuity from occurring even at the seams of the devices.

It goes without saying that the present invention is effective not only in one-dimensional photoelectric conversion devices but also in two-dimensional photoelectric conversion devices. When the present invention is applied to a two-dimensional photoelectric conversion device, in addition to the resolution switching at the pixel level, the resolution switching only in the horizontal direction and the resolution switching only in the vertical direction can be realized.

[0069]

As described above, according to the present invention, the signal does not become discontinuous at the seam of the photoelectric conversion device and the reading speed according to the resolution can be obtained even when the resolution is switched. It is overwhelming.

When used in an image scanner, a facsimile, an electronic copying machine, or the like using the contact type image sensor, it is possible to output in accordance with the image quality required for the transferred paper, such as high image quality, normal image quality, and the like. And increase the degree of freedom in function.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of a contact image sensor according to a first embodiment of the present invention.

FIG. 2 is a circuit block diagram of an 8-bit shift register and a light receiving element according to the embodiment of the present invention.

FIG. 3 is an equivalent circuit diagram (for four pixels) of the light receiving element according to the embodiment of the present invention.

FIG. 4 is a timing chart showing an operation according to the embodiment of the present invention.

FIG. 5 is a circuit block diagram of a contact image sensor using a photoelectric conversion device according to a second embodiment of the present invention.

FIG. 6 is a circuit diagram of a start signal switching circuit according to a second embodiment of the present invention.

FIG. 7 is a circuit diagram of an integrated circuit for a contact image sensor according to the related art (1).

FIG. 8 is an equivalent circuit diagram of an image sensor chip according to the related art (2).

FIG. 9 is a timing chart in the related art (2).

[Explanation of symbols]

1, 1 'photoelectric exchange device 2, 2' pre-shift register 3, 3 'shift register 4, 4' light receiving element array 5, 5 'timing generation circuit 7, 7' shift register drive pulse (Φ1) 8, 8 'shift Register driving pulse (Φ2) 9, 9 'Next chip start signal line 9-1, 9-1' High resolution mode start signal line 9-2, 9-2 'Low resolution mode start signal line 10, 10 'Start signal switching means 11 Shift register block (4 bits) 12-1 to 12-4' 1-bit synchronous 1-bit shift register 13-1 to 13-4 '1-bit synchronous 1-bit shift register 14 Common signal lines a1 to d2 Element Φa1 to Φd2 a1 to d2 Read pulse M1a to M1d Read switch M4a to M4d Reset switch PDa to PDd Photo diode De

Claims (7)

[Claims] A light-receiving element array in which a plurality of light-receiving elements are arranged at a first resolution; a first shift register driving pulse for reading out odd-numbered light-receiving elements of the light-receiving element array; and an even-numbered light-receiving element array Scanning means driven by a second shift register driving pulse for reading the light receiving element, and a resolution for switching between the first resolution and a second resolution which is 1 / N (N is a natural number) of the first resolution. A photoelectric conversion device comprising: a switching unit; wherein the number of the plurality of light receiving elements is a multiple of 2N. 2. A light-receiving element array in which a plurality of light-receiving elements are arranged at a first resolution; a first shift register driving pulse for reading out odd-numbered light-receiving elements of the light-receiving element array; and an even-numbered light-receiving element array. Scanning means driven by a second shift register driving pulse for reading the light receiving element, and a resolution for switching between the first resolution and a second resolution which is 1 / N (N is a natural number) of the first resolution. A contact image sensor configured by mounting a plurality of photoelectric conversion devices having switching means, wherein the number of light receiving elements of the photoelectric conversion device is a multiple of 2N. 3. A light-receiving element array in which a plurality of light-receiving elements are arranged at a first resolution; a first shift register drive pulse for reading out odd-numbered light-receiving elements of the light-receiving element array; and an even-numbered light-receiving element array. Scanning means driven by a second shift register driving pulse for reading the light receiving element, and a resolution for switching between the first resolution and a second resolution which is 1 / N (N is a natural number) of the first resolution. Switching means, wherein the first light receiving element of the light receiving element array is read out by the first shift register driving pulse, and the last light receiving element is read out by the second shift register driving pulse. A photoelectric conversion device, which is read. 4. A light-receiving element array in which a plurality of light-receiving elements are arranged at a first resolution; a first shift register drive pulse for reading out odd-numbered light-receiving elements of the light-receiving element array; and an even-numbered light-receiving element array. Scanning means driven by a second shift register driving pulse for reading the light receiving element, and a resolution for switching between the first resolution and a second resolution which is 1 / N (N is a natural number) of the first resolution. A contact type image sensor configured by mounting a plurality of photoelectric conversion devices having switching means, wherein the first light receiving element of the light receiving element array is read by the first shift register drive pulse, and Wherein the light receiving element is read out by the second shift register driving pulse. 5. An image sensor in which a plurality of photoelectric conversion devices including a plurality of light receiving elements are connected, wherein a resolution selecting means for selecting a resolution, and a resolution selected by the resolution selecting means in each of the photoelectric conversion devices. Control means for changing a method of reading a signal from a light receiving element, and signal reading means for reading a signal from the light receiving element with a plurality of pulses, the signal reading means periodically driving a plurality of pulses,
An image sensor, wherein the number of light receiving elements arranged is set such that a signal read first from the signal reading means in each photoelectric conversion device is read by the same pulse among the plurality of pulses. 6. An image sensor in which a plurality of photoelectric conversion devices including a plurality of light receiving elements are connected, wherein a resolution selection for selecting any one of a plurality of resolutions whose resolution changes by 1 / N (N is a positive integer). Means, a control means for changing a method of reading a signal from the light-receiving drug element according to the resolution selected by the resolution selecting means in each photoelectric conversion device, and M (M is a positive integer) from the light-receiving element. An image sensor, comprising: signal readout means for reading out a signal by a plurality of shift register drive pulses, wherein the plurality of light receiving elements are multiples of MN. 7. A light-receiving element array in which a plurality of light-receiving elements are arranged at a first resolution, a first shift register driving pulse for reading out odd-numbered light-receiving elements of the light-receiving element array, and an even-numbered light-receiving element array Scanning means driven by a second shift register driving pulse for reading out the first light receiving element; the first resolution and 1 / N of the first resolution.
(N is a natural number) a resolution switching means for switching between a second resolution and a second resolution. An image reading apparatus using a contact type image sensor configured by mounting a plurality of photoelectric conversion apparatuses, An image reading apparatus, wherein the number of elements is a multiple of 2N, and a switch for switching between the first resolution and the second resolution is provided.