JPH06189065A - Image sensor provided with constant current circuit and image information processor - Google Patents

Abstract

PURPOSE:To enable high-speed reading by increasing the frequency of a clock signal without requiring any complicated external circuit to cause the increase of cost. CONSTITUTION:This multichip type image sensor arranging plural image sensor chips 1-1 provided with photodetectors 2-1-1-2-1-n is provided with an optical signal amplifying means 6-1 for amplifying optical signals detected by the photodetectors 2-1-2-2-1-n, first constant current control means 5-1 for letting a current in a normal state flow only during the optical signal output term of the image sensor chips corresponding to the constant current circuit of the optical signal amplifying means 6-1, and second constant current control means 10-1 for letting a constant current reduced rather than the normal state flow to the constant current circuit out of the optical signal output term at least.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image sensor and an image information processing apparatus using the same, and more particularly to an image sensor for reading an image by photoelectric conversion of a light receiving element and an image information processing apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, linear image sensors have been widely used as reading devices in facsimiles, scanners and the like.
Since these linear image sensors are formed on a silicon wafer, the sensor length is limited by the wafer size, and it is difficult to make a linear image sensor chip with the same length as the original, and the sensor length is short. Often you can only get it.

For this reason, when a reading device is constituted by one linear image sensor, the reflected light from the original is reduced by an optical system to be reduced and projected on the linear image sensor to read an image. However, in a reader using such a reduction optical system, a large space is required for the optical system, and the resolution is not sufficient. Therefore, as a solution to this problem, there is a reading device using a multi-chip type image sensor in which a plurality of linear image sensors are arranged in a straight line.

FIG. 5 shows a structure of a multi-chip type image sensor using a conventional image sensor chip.
FIG. 6 is a diagram showing an operation waveform (timing chart).

In FIG. 5, 1-1, 1-2, ...
, 1-m are image sensor chips, and each chip (hereinafter, image sensor chip may be abbreviated as a chip) is connected to form a multi-chip type image sensor. Image sensor chip 1
In -1, 2-1-1 to 2-1-n are light receiving elements, which convert an input optical signal into an electric signal.

In this multi-chip type image sensor, by arranging and connecting the light-receiving elements from 2-1-1 to 2-m-n, the sensor length is made long and it is possible to cope with a large document size.

The multi-chip type image sensor operates in synchronization with the clock signal from the clock terminal 9 and the start signal is input from the start terminal 8 to the first chip 1-1. Be started.
Receiving this start signal, the shift registers 4-1-1 to 4-1-1
4-1-n sequentially turns on the MOS switches 3-1-1 to 3-1-n in synchronization with the clock signal, and the light receiving elements 2-1-1 to 2-1 connected to the respective MOS switches. n is activated to read out the optical signal.

This optical signal is amplified by the optical signal output amplifier 6-1 and output to the output terminal 7 as an optical output signal. Further, if the optical signal output amplifier 6-1 is always in the operating state, it causes increase in power consumption.
A constant current control circuit 5-1 for switching the -1 constant current circuit between the operating state and the non-operating state is provided. When the first shift register 4-1-1 receives the start signal, the constant current control circuit 5-1 activates the optical signal output amplifier 6-1 at about the same time as setting the constant current circuit in the operating state.

The output from the shift register 4-1-n at the final stage of the chip 1-1 is the MOS switch 3 at the final stage.
At the same time when -1-n is turned on, it is output to the outside of the chip 1-1 and the first shift register 4-2 of the next chip 1-2.
It is input to -1 as a start signal.

Also in the next-stage chip 1-2, the above-mentioned chip 1
−1, the same operation is performed, and the chip 1-3 of the next stage
A start signal is output (not shown). In this way, by sequentially outputting the start signal to the next chip,
The reading operation of the optical signal of the sensor length is executed.

FIG. 6 is a diagram showing operation waveforms (timing chart) of the above-described multi-chip type image sensor. In the figure, after the time S from the output of the start signal to the chip 1-2, the light receiving element 2-2- of the chip 1-2
It can be seen that the optical signal from 1 has been read and that chip 1-2 must start the constant current circuit of the amplifier during this time S. Further, since the time S decreases as the clock frequency increases, the constant current circuit must be started up in a short time.

[0012]

As described above, in the above conventional example, the optical signal is read from the light receiving element 2-1-1 by the input of the start signal and the optical signal output amplifier 6-amplifies the optical signal. The startup of the constant current circuit of 1,
Since it is almost the same time, in order to read the optical signal after the constant current circuit is completely started up, it is necessary to lower the frequency of the clock signal and take a sufficiently long reading time of the light receiving element per pixel. .

Here, if the frequency of the clock signal is increased in order to shorten the read time and increase the speed,
A problem that the constant current circuit is not completely started up, that is, the optical signal is output from the light receiving element before the optical signal output amplifier 6-1 completely enters the operating state, and accurate signal amplification cannot be performed. There is a point. There is also a method of slowing the frequency only for the clock for the first light receiving element of each chip, but this requires a complicated circuit to be externally provided, which causes a problem of cost increase.

Therefore, even if an attempt is made to increase the frequency of the clock signal in order to shorten the optical signal reading time of the multi-chip type image sensor and perform high-speed reading, the rise time of the constant current circuit is limited.

An object of the present invention is to realize a multi-chip type image sensor capable of high-speed reading by increasing the frequency of a clock signal without requiring an external complicated circuit which causes the above-mentioned cost increase. It is in.

[0016]

The image sensor of the present invention is a multi-chip type image sensor in which a plurality of image sensor chips each having a light receiving element are arranged, and an optical signal amplifying means for amplifying an optical signal by the light receiving element. When,
The first constant current control means for supplying a steady-state current only during the optical signal output period of the image sensor chip corresponding to the constant current circuit of the optical signal amplifying means, and for not supplying the current outside the optical signal output period, and at least the light Second constant current control means for supplying a constant current reduced from the steady state to the constant current circuit outside the signal output period.

The image sensor of the present invention further comprises a light receiving element, an optical signal amplifier circuit for amplifying an optical signal of the light receiving element,
An image sensor having a constant current control circuit for supplying a current to a constant current circuit of the optical signal amplifier circuit, wherein the constant current control circuit has a first period during an output period in which an optical signal output of the image sensor is output. A first control circuit for supplying a constant current and not supplying the first constant current in a non-output period, and a second control circuit for supplying a second constant current different from the first constant current in the non-output period. And a control circuit of.

The image information processing apparatus of the present invention is an image having a multi-chip type image sensor in which a plurality of image sensor chips having light receiving elements are arranged, and a circuit for processing an optical signal from the image sensor. In the information processing device, each image sensor chip is in a steady state only during an optical signal output period of the image sensor chip corresponding to the optical signal amplifying means for amplifying the optical signal by the light receiving element and the constant current circuit of the optical signal amplifying means. A first constant current control means for supplying a current and not supplying a current outside the optical signal output period, and a second constant current for supplying a constant current lower than the steady state to the constant current circuit at least outside the optical signal output period. And a control means.

[0019]

According to the present invention, a steady-state current is supplied to the constant current circuit of the optical signal amplifying means for amplifying the optical signal by the light receiving element only during the optical signal output period of the image sensor chip, and no current is supplied outside the optical signal output period. By providing the first constant current control means and the second constant current control means for flowing a constant current reduced from the steady state to the constant current circuit at least outside the optical signal output period, outside the optical signal output period Also, a constant current is supplied to the constant current circuit of the optical signal amplifying means to shorten the rise time of the constant current circuit. As a result, it is possible to increase the frequency of the clock signal and perform high-speed reading without the need for an external complicated circuit that causes a cost increase.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a configuration of an embodiment of an image sensor chip according to the present invention and a multi-chip type image sensor using the same. The same components as those in FIG. 5 are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 1, image sensor chips 1-1, 1-2, ... 1-m are arranged and provided, and each image sensor chip 1-1 to 1-m is provided. ,
Constant current control circuit 5-1 for switching the constant current circuit of the optical signal output amplifiers 6-1 to 6-m between the operating state and the non-operating state
.About.5-m (which serves as the first constant current control means), the constant current circuits of the optical signal output amplifiers 6-1 to 6-m are reduced from the constant current control circuits 5-1 to 5-m. Constant current control circuit for supplying constant current (serving as second constant current control means) 10-1 to 10
0-m is provided.

FIG. 2 is a diagram showing an example of a constant current control circuit and an optical signal output amplifier provided in the image sensor chip of the present invention. In the figure, transistors Q1 to Q3,
A circuit composed of a diode D1 and resistors R1 and R2 (in the figure,
(A part) is each constant current control circuit 5-1 to 5- shown in FIG.
Configure m. A circuit (section B in the figure) composed of the transistors Q4 and Q5, the diode D2, and the resistors R3 and R4 constitutes each constant current control circuit 10-1 to 10-m shown in FIG. A circuit composed of the transistors Q6 to Q15 and the diodes D3 and D4 constitutes each optical signal output amplifier 6-1 to 6-m shown in FIG. 11 is a power supply terminal, 1
2 is a constant current control terminal, 13 is a ground terminal, and 14 and 15 are amplifier input terminals.

Next, the operation of the image sensor chip and the multi-chip type image sensor using the same will be described.

First, when the first shift register 4-1-1 receives the start signal, the constant current control circuit 5-1 outputs the light during the time S as shown by the operation waveform of the multi-chip type image sensor of FIG. The constant current circuit of the signal output amplifier 6-1 is activated. The constant current control circuit 10-1 is different from the constant current control circuit 5-1 in that the optical signal output amplifier 6-
The constant current reduced by the constant current control circuit 5-1 is supplied to the first constant current circuit.

This operation will be further described with reference to FIG. 2. The constant current control circuit 5-1 (A in FIG. 2) has the transistor Q only during the optical signal output period of the image sensor chip.
1 is turned off and a current is supplied to the constant current circuit of the amplifier of the transistors Q6, Q7 and Q12, and the transistor Q1 is turned on and the transistors Q6, Q7 and Q12 are outside the optical signal output period.
Do not apply current to the constant current circuit of the amplifier. However, the constant current control circuit 10-1 (section B in FIG. 2) causes a current that is lower than usual to flow through the constant current circuits of the transistors Q6, Q7, and Q12. As a result, the potential of each node of the amplifier is held at a constant value even outside the optical signal output period, and the time during which the amplifier can operate after the constant current control circuit 5-1 operates is shortened. This means that the time S shown in FIG. 6 can be shortened.

The NPN transistor shown in FIG.
PNP transistor, MOS transistor Q1 to Q15
The conductivity type is not particularly limited, and the types of the constant current control circuit and the amplifier circuit are not particularly limited.
Further, a photodiode or a phototransistor is applied as the light receiving element of the present invention. More preferably, a phototransistor is used to form an emitter follower circuit including a capacitive load.

A contact type sensor unit using the above multi-chip type image sensor and an image information processing apparatus using the same will be described below.

FIG. 3 is a sectional view showing the structure of the contact type sensor unit. As shown in FIG. 3, a transparent glass plate 1201 in contact with the original surface is attached to the upper surface of a housing 1200, and the emitted light 1212 is Transparent glass plate 1201
The LEDs 1211 are provided in the housing 1200 in a state of being arranged on the substrate 1210 at a predetermined angle so that they are reflected by the document surface in contact with the upper surface of the transparent glass plate 120.
An optical system 1209 that allows one reflected light 1213 to pass therethrough, and a multichip type image sensor 1001 provided on a substrate 1006 corresponding to this optical system are provided in a housing 1200.

Multi-chip type image sensor 1001
Is covered with a protective film 1206 on the substrate 1006,
A thin metal wire 1208 electrically connects to a desired circuit on the substrate 1006, and the substrate 1006 is a housing 1200.
The rubber plate 1207 is supported by the bottom plate 1205 engaged with the. In addition, the end plates 1 are provided at both ends of the housing 1200.
203 is attached with screws 1204. Also the housing 12
00 is provided with a connector for inputting / outputting an external power source, a control signal, etc., such as a facsimile main body.

FIG. 4 is a schematic block diagram showing an example of a facsimile having a communication function as an image information processing apparatus constructed by using the contact type sensor unit.

In the figure, E is an image reading unit, 1108.
Is a feed roller as a feeding means for feeding the document 1118 toward the reading position, and 1117 is the document 1118.
It is a separating piece for surely separating and feeding the sheets one by one. 1
A platen roller 116 is provided at the reading position with respect to the sensor unit 1110, regulates the surface to be read of the document 1118, and serves as a transport unit that transports the document 1118.

Reference numeral 1114 denotes a recording medium in the form of a roll paper in the illustrated example, and on the recording paper from which the image information read by the sensor unit 1110 or the image information transmitted from the outside in the case of a facsimile machine is taken out. Is played. Reference numeral 1111 denotes a recording head as a recording unit for performing the image formation, and various types such as a thermal head and an inkjet recording head can be used. The recording head may be of a serial type or a line type. Reference numeral 1115 denotes a platen roller as a conveying unit that conveys the recording medium 1114 to the recording position of the recording head 1111 and regulates the recording surface of the recording medium 1114.

Reference numeral 1101 denotes an operation panel provided with a switch for accepting an operation input as an input / output means, a message, and a display section for notifying the state of the apparatus.

Reference numeral 1112 is a system control board as a control means, which includes a control section (controller) for controlling each section, a drive circuit (driver) for the photoelectric conversion element, an image information processing section (processor), a transmission / reception section, and the like. It is provided. Reference numeral 1113 is a power source of the apparatus, 1114 is a guide stage for the document insertion port, and 1109 is a metal fitting for fixing the sensor unit.

As the recording means used in the above information processing apparatus, for example, US Pat. Nos. 4,723,129 and 47407 are applicable.
It is preferable that the 96th specification discloses its typical structure and principle. According to this method, at least one of the electrothermal converters arranged corresponding to the sheet or liquid path holding the liquid (ink) gives a rapid temperature rise corresponding to the recorded information and exceeding the nucleate boiling. By applying a drive signal, heat energy is generated in the electrothermal converter, causing film boiling on the heat-acting surface of the recording head, and as a result, bubbles in the liquid (ink) that correspond one-to-one to this drive signal. Is effective because it can form The liquid (ink) is ejected through the ejection openings by the growth and contraction of the bubbles to form at least one droplet.

Further, as a full line type recording head having a length corresponding to the width of the maximum recording medium which can be recorded by the recording device, a combination of a plurality of recording heads as disclosed in the above-mentioned specification is used. Either a structure that satisfies the length or a structure as one recording head integrally formed may be used.

In addition, the ink can be attached to the replaceable chip type recording head or the recording head itself, which can be electrically connected to the apparatus main body and can be supplied with ink by being attached to the apparatus main body. This is also effective when a cartridge-type recording head integrally provided with a tank is used.

[0039]

As described above, according to the present invention,
In addition to the first constant current control unit that applies a steady-state current only during the optical signal output period and does not apply a current outside the optical signal output period, a second constant current that is reduced from the steady state during the optical signal output period is also applied. By providing the constant current control means of (1), it is possible to realize a multi-chip type image sensor capable of high-speed reading by increasing the frequency of the clock signal without requiring an external complicated circuit which causes a cost increase. You can

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of an image sensor chip according to the present invention and a multi-chip type image sensor using the same.

FIG. 2 is a diagram showing an embodiment of a constant current control circuit and an optical signal output amplifier circuit of the image sensor chip of the present invention.

FIG. 3 is a cross-sectional view showing a configuration of a contact type sensor unit.

FIG. 4 is a schematic configuration diagram showing an example of a facsimile having a communication function as an image information processing apparatus configured by using a contact type sensor unit.

FIG. 5 is a diagram showing a configuration of a multi-chip type image sensor using a conventional image sensor chip.

FIG. 6 is a diagram showing operation waveforms (timing chart).

[Explanation of symbols]

1-1 to 1-m image sensor chip 2-1-1 to 2-m-n light receiving element 3-1-1 to 3-m-n light receiving element switching MOS switch 4-1-1 to 4-m-n Shift register 5-1 to 5-m constant current control circuit 6-1 to 6-m optical signal output amplifier 7 output terminal 8 start terminal 9 clock terminal 10-1 to 10-m constant current control circuit 11 power supply terminal 12 constant current Control terminal 13 Ground terminal 14, 15 Amplifier input terminal

Claims (3)

[Claims] 1. A multi-chip type image sensor in which a plurality of image sensor chips each having a light receiving element are arranged, and an optical signal amplifying means for amplifying an optical signal by the light receiving element, and a constant current circuit of the optical signal amplifying means. Corresponding to the first constant current control means that allows a steady-state current to flow only during the optical signal output period of the image sensor chip and does not flow current outside the optical signal output period, and at least the constant current circuit outside the optical signal output period. And a second constant current control means for supplying a constant current reduced from the steady state to the image sensor. 2. An image sensor having a light receiving element, an optical signal amplifier circuit for amplifying an optical signal of the light receiving element, and a constant current control circuit for supplying a current to a constant current circuit of the optical signal amplifier circuit. The constant current control circuit includes a first control circuit that applies a first constant current during an output period in which an optical signal output of the image sensor is output and does not apply a first constant current during a non-output period, An image sensor, comprising: a second control circuit for flowing a second constant current different from the first constant current in the non-output period. 3. A multi-chip type image sensor in which a plurality of image sensor chips each having a light receiving element are arranged, and a circuit which processes an optical signal from the image sensor.
In the image information processing apparatus having the above, each image sensor chip has an optical signal amplifying means for amplifying an optical signal by the light receiving element, and an optical signal output period of the image sensor chip corresponding to the constant current circuit of the optical signal amplifying means. A first constant current control unit that supplies a steady-state current and does not supply a current outside the optical signal output period, and a second constant current circuit that supplies a constant current that is lower than the steady state to the constant current circuit at least outside the optical signal output period. An image information processing apparatus, comprising: