JP3216097B2 - Image sensor having constant current circuit and image information processing apparatus - Google Patents

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, a linear image sensor is frequently used as a reading device in a facsimile, a scanner or the like.
Since these linear image sensors are created on a silicon wafer, their sensor length is limited by the wafer size, making it difficult to make a linear image sensor chip of the same length as the original document. Often you can only get.

For this reason, when a reading device is constituted by one linear image sensor, an image is read by reducing the reflected light from the original using an optical system and projecting the reflected light onto the linear image sensor. However, in a reading apparatus using such a reduction optical system, a large space is required for the optical system, and the resolution is not sufficient. In order to solve this problem, there is a reading apparatus using a multi-chip type image sensor in which a plurality of linear image sensors are arranged on a straight line.

FIG. 5 shows a configuration of a multi-chip type image sensor using a conventional image sensor chip.
FIG. 3 is a diagram showing an operation waveform (timing chart).

In FIG. 5, 1-1, 1-2,...
, 1-m are image sensor chips, and the respective chips (hereinafter, may be abbreviated as image sensor chips) are connected to form a multi-chip 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.

The multi-chip type image sensor has a long sensor length by connecting and connecting light receiving elements from 2-1-1 to 2-mn so that a large original size can be accommodated.

The operation of this multi-chip type image sensor is synchronized by a clock signal from a clock terminal 9 and a start signal is inputted from a start terminal 8 to the first chip 1-1. Be started.
In response to the start signal, the shift registers 4-1-1 to 4-1-1
4-1-n turns on the MOS switches 3-1-1 to 3-1-1-n sequentially in synchronization with the clock signal, and the light receiving elements 2-1-1 to 2-1-1 connected to each MOS switch. n is operated to read out an 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. In addition, if the optical signal output amplifier 6-1 is always operated, power consumption increases.
A constant current control circuit 5-1 is provided for switching the -1 constant current circuit between an operating state and a non-operating state. When the first shift register 4-1-1 receives the start signal, the constant current control circuit 5-1 activates the constant current circuit almost at the same time as the start signal, and enables the optical signal output amplifier 6-1 to operate.

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

In the next chip 1-2, the chip 1 described above is used.
-1 and the next stage chip 1-3
(Not shown), a start signal is output. By sequentially outputting the start signal to the next chip in this manner,
The reading operation of the optical signal of the sensor length is performed.

FIG. 6 is a diagram showing an operation waveform (timing chart) of the above-described multi-chip type image sensor. In the figure, the light receiving element 2-2 of the chip 1-2 after a time S from the output of the start signal to the chip 1-2.
1 indicates that the chip 1-2 must start the constant current circuit of the amplifier during this time S. Further, when the clock frequency is increased, the time S is also reduced, so that the rise time of the constant current circuit must be performed in a short time.

[0012]

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

Here, in order to shorten the read time and increase the speed, the frequency of the clock signal is increased.
A problem that the constant current circuit does not completely start up, that is, an 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. In addition, there is a method of lowering the frequency of only the clock for the first light receiving element of each chip. However, this requires a complicated circuit to be provided externally, which causes a problem of an increase in cost.

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]

According to the present invention, there is provided an image sensor, comprising: a light receiving element; and a moving element for amplifying an optical signal from the light receiving element.
A plurality of image sensor chips having an optical signal amplifying circuit including a constant current circuit for flowing a constant current for performing the operation, and a constant current control unit for controlling a current flowing to the constant current circuit, are arranged in plurality, In a multi-chip image sensor in which optical signals are sequentially output from each image sensor chip, the constant current control means includes a first constant current control circuit and a second constant current control connected to the constant current circuit, respectively. Wherein the first constant current control circuit performs an operation of flowing current during an output period for outputting the optical signal from the image sensor chip and does not perform an operation of flowing current during a non-output period. The second constant current control circuit is a circuit that performs an operation of flowing a current during the non-output period, and is controlled by the first and second constant current control circuits during the non-output period. The constant current flowing through the flow circuit, characterized by less than the constant current flowing through the constant current circuit in the output period.

Further, the image sensor of the present invention causes a light receiving element and an operation of amplifying an optical signal from the light receiving element to be performed.
An optical signal amplifying circuit including a constant current circuit for flowing a constant current for controlling the current flowing through the constant current circuit, and a constant current control means for controlling a current flowing to the constant current circuit. A first circuit connected to each of the current circuits;
A constant current control circuit and a second constant current control circuit, wherein the first constant current control circuit performs an operation of flowing a current during an output period for outputting the optical signal from the image sensor. The second constant current control circuit is a circuit that does not perform an operation of flowing a current during an output period, and the second constant current control circuit is a circuit that performs an operation of flowing a current during the non-output period, and the first and second constant current control circuits are The constant current flowing through the constant current circuit during the non-output period is smaller than the constant current flowing through the constant current circuit during the output period.

Further, the image information processing apparatus of the present invention has a light receiving element and an operation for amplifying an optical signal from the light receiving element.
A plurality of image sensor chips each having an optical signal amplifier circuit including a constant current circuit for supplying a constant current for controlling the current and a constant current control means for controlling a current supplied to the constant current circuit; In a multi-chip type image sensor in which optical signals are sequentially output from a chip, and a circuit that processes the optical signals output from the image sensor, in the image information processing apparatus, the constant current control means,
A first constant current control circuit and a second constant current control circuit respectively connected to the constant current circuit;
The constant current control circuit performs an operation of flowing a current during an output period for outputting the optical signal from the image sensor chip,
The second constant current control circuit is a circuit that does not perform an operation of flowing a current during the non-output period, and the second constant current control circuit is a circuit that performs an operation of flowing a current during the non-output period, and the first and second constant current controls The circuit is configured such that a constant current flowing through the constant current circuit during the non-output period is smaller than a constant current flowing through the constant current circuit during the output period.

[0019]

According to the present invention, a steady-state current flows only during the optical signal output period of the image sensor chip to the constant current circuit of the optical signal amplifying means for amplifying the optical signal by the light receiving element, and no current flows outside the optical signal output period. By providing a first constant current control means and a second constant current control means for supplying a constant current reduced from a steady state to the constant current circuit at least 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 perform high-speed reading by increasing the frequency of the clock signal without requiring an external complicated circuit that causes a cost increase.

[0020]

An embodiment of the present invention will be described below with reference to the drawings.

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

As shown in FIG. 1, image sensor chips 1-1, 1-2,..., 1-m are arranged and provided. ,
A constant current control circuit 5-1 for switching the constant current circuits of the optical signal output amplifiers 6-1 to 6-m between an operation state and a non-operation state.
-5-m (becomes the first constant current control means), and 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. A constant current control circuit for flowing a constant current (to be a second constant current control means) 10-1 to 10-1
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,
Part A) is each of the constant current control circuits 5-1 to 5- shown in FIG.
m. A circuit (part B in the figure) including the transistors Q4 and Q5, the diode D2, and the resistors R3 and R4 constitutes each of the constant current control circuits 10-1 to 10-m shown in FIG. A circuit including the transistors Q6 to Q15 and the diodes D3 and D4 constitutes each of the optical signal output amplifiers 6-1 to 6-m shown in FIG. 11 is a power 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 operation of a multi-chip 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 emits light during the time S as shown by the operation waveform of the multi-chip image sensor in FIG. The constant current circuit of the signal output amplifier 6-1 is started. Further, the constant current control circuit 10-1 is different from the constant current control circuit 5-1.
The constant current, which is lower than that of the constant current control circuit 5-1, is passed through one constant current circuit.

This operation will be further described with reference to FIG. 2. The constant current control circuit 5-1 (part A in FIG. 2) operates the transistor Q only during the optical signal output period of the image sensor chip.
1 is turned off and a current flows 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 turned on outside the optical signal output period.
No current flows through the constant current circuit of the amplifier. However, the constant current control circuit 10-1 (part B in FIG. 2) causes the constant current circuit of the transistors Q6, Q7, Q12 to flow a current smaller than usual. As a result, the potential of each node of the amplifier is kept at a constant value even outside the optical signal output period, and the time during which the amplifier becomes operable after the operation of the constant current control circuit 5-1 is reduced. This means that the time S shown in FIG. 6 can be shortened.

The NPN transistor shown in FIG.
PNP transistor, MOS transistor Q1-Q15
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, an emitter follower circuit including a capacitive load using a phototransistor is desirable.

Hereinafter, a contact type sensor unit using the multi-chip type image sensor and an image information processing apparatus using the same will be described.

FIG. 3 is a cross-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 document surface is mounted on the upper surface of a housing 1200, and the emitted light 1212 Transparent glass plate 1201
The LED 1211 is provided in the housing 1200 in a state where the LED 1211 is arranged on the substrate 1210 at a predetermined angle such that the LED 1211 is reflected by the original surface in contact with the upper surface of the transparent glass plate 120.
An optical system 1209 for transmitting one reflected light 1213 and a multi-chip image sensor 1001 provided on a substrate 1006 corresponding to the optical system are provided in a housing 1200.

A multi-chip type image sensor 1001
Is covered with a protective film 1206 on the substrate 1006,
The thin metal wire 1208 is electrically connected to a desired circuit on the substrate 1006, and the substrate 1006 is
Is supported via a rubber plate 1207 on the bottom plate 1205 which is engaged with. Note that end plates 1 are provided at both ends of the housing 1200.
203 is mounted with a screw 1204. In addition, housing 12
00 is provided with an input / output connector for an external power supply and control signals, such as a facsimile body.

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

In the figure, E denotes an image reading unit, 1108
A feeding roller as feeding means for feeding the original 1118 toward the reading position, and 1117 an original 1118
For reliably separating and feeding the sheets one by one. 1
Reference numeral 116 denotes a platen roller which is provided at a reading position with respect to the sensor unit 1110 and regulates the surface to be read of the original 1118 and also conveys the original 1118.

Reference numeral 1114 denotes a recording medium in the form of a roll paper in the example shown in the figure. Will be played. Reference numeral 1111 denotes a recording head as recording means for forming the image, and various types such as a thermal head and an ink jet 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 transport unit that transports the recording medium 1114 to a recording position of the recording head 1111 and regulates a recording surface thereof.

Reference numeral 1101 denotes an operation panel provided with switches and messages for accepting operation inputs as input / output means, and a display unit for notifying the state of the apparatus and the like.

Reference numeral 1112 denotes a system control board as control means, which includes a control unit (controller) for controlling each unit, a drive circuit (driver) for the photoelectric conversion element, a processing unit (processor) for image information, a transmission / reception unit, and the like. Provided. Reference numeral 1113 denotes a power supply of the apparatus, reference numeral 1114 denotes a guide stage of a document insertion slot, and reference numeral 1109 denotes a bracket for fixing the sensor unit.

As the recording means used in the information processing apparatus, for example, US Pat. Nos. 4,723,129 and 47,407
It is preferable that the typical structure and principle are disclosed in Japanese Patent No. 96-96. According to this method, at least one of the electrothermal transducers corresponding to the recorded information and having a rapid temperature rise exceeding the nucleate boiling is applied to the electrothermal transducer disposed corresponding to the sheet or the liquid path holding the liquid (ink). By applying a drive signal, heat energy is generated in the electrothermal transducer, causing the film to boil on the heat-acting surface of the recording head. As a result, bubbles in the liquid (ink) corresponding to the drive signal one-to-one. Is effective because By discharging the liquid (ink) through the discharge opening by the growth and contraction of the bubble, at least one droplet is formed.

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

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

[0039]

As described above, according to the present invention,
Apart from the first constant current control means, which supplies a steady-state current only during the optical signal output period and does not supply a current outside the optical signal output period, a second constant current, which is lower than the steady state outside the optical signal output period, flows. By providing the constant current control means, it is possible 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 an increase in cost. Can be.

[Brief description of 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.

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 illustrating a configuration of a contact sensor unit.

FIG. 4 is a schematic configuration diagram illustrating an example of a facsimile having a communication function as an image information processing device configured 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 an operation waveform (timing chart).

[Explanation of symbols]

1-1 to 1-m Image sensor chip 2-1-1 to 2-mn Light receiving element 3-1-1 to 3-mn Light receiving element switching MOS switch 4-1-1 to 4-mn 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)

(57) [Claims] 1. A light receiving element and a constant current circuit for flowing a constant current for performing an operation of amplifying an optical signal from the light receiving element.
An optical signal amplifying circuit comprising, a current flowing to the constant current circuit control
And constant current control means for control, is an image sensor chip is a plurality sequence having, in a multi-chip type image sensor of the optical signal from each image sensor chip are sequentially output, the constant current control means, said constant A first constant current control circuit and a second constant current control circuit respectively connected to a current circuit, wherein the first constant current control circuit outputs the optical signal from the image sensor chip. The second constant current control circuit is a circuit that performs an operation of flowing a current during a period and does not perform an operation of flowing a current during a non-output period, and the second constant current control circuit is a circuit that performs an operation of flowing a current during the non-output period. The first and second constant current control circuits reduce a constant current flowing through the constant current circuit during the non-output period to be smaller than a constant current flowing through the constant current circuit during the output period. An image sensor, comprising: 2. A constant current circuit for flowing a constant current for performing an operation of amplifying an optical signal from the light receiving element.
An optical signal amplifying circuit comprising, a current flowing to the constant current circuit control
And a constant current control means for controlling the constant current control means, wherein the constant current control means includes a first constant current control circuit and a second constant current control circuit respectively connected to the constant current circuit. The first constant current control circuit is a circuit that performs an operation of flowing a current during an output period in which the optical signal is output from the image sensor and does not perform an operation of flowing a current during a non-output period. The constant current control circuit 2 is a circuit that performs an operation of flowing a current during the non-output period. The first and second constant current control circuits reduce a constant current flowing through the constant current circuit during the non-output period. An image sensor, wherein the current is smaller than a constant current flowing through the constant current circuit during the output period. 3. A constant current circuit for supplying a constant current for performing an operation of amplifying an optical signal from the light receiving element.
An optical signal amplifying circuit comprising, a current flowing to the constant current circuit control
And constant current control means for control, is an image sensor chip plurality sequences having a multi-chip type image sensor in which optical signals are sequentially output from the image sensor chip, optical signal output from said image sensor A constant current control circuit, wherein the constant current control means includes a first constant current control circuit and a second constant current control circuit connected to the constant current circuit, respectively. The first constant current control circuit is a circuit that performs an operation of flowing a current during an output period when the optical signal is output from the image sensor chip and does not perform an operation of flowing a current during a non-output period. A constant current control circuit for performing an operation of flowing a current during the non-output period; and a constant current control circuit for controlling the constant current during the non-output period by the first and second constant current control circuits. Image information processing apparatus characterized by a constant current flowing through the flow circuit, smaller than the constant current flowing through the constant current circuit in the output period.