JP2984358B2 - Image sensor and information processing apparatus equipped with the sensor - Google Patents

Description

The present invention relates to an information processing apparatus such as a copying machine, a facsimile, and an image reader, and more particularly, to an image sensor used for the information processing apparatus.

(Conventional example)

As a contact type image sensor, there is a type in which a plurality of image sensor chips having pixels for copying are arranged and the image information is read one-to-one as long as the width of the document to be read.

FIG. 4 shows an example of a pixel of such an image sensor conventionally used. Here, the reading width in the main scanning direction of all the pixels including the pixels at the ends is constant (b) and the reading width in the sub-scanning direction is constant (a).

[Problems to be solved by the invention]

However, in FIG. 4, the pixel at the end (2-D, 2
−E) and the other pixels 2-A, 2-B, 2-C, 2-F have different output signals due to different crosstalk components flowing from adjacent pixels. For example, for pixel 2-B, pixel 2
While the crosstalk components of the signal charges from both -A and 2-C flow in, only the crosstalk components of the signal charges from the pixel 2-C flow into the pixel 2-D. As a result, the output signals from the pixels 2-D, 2-E at the end are lower than the output signals from the other pixels 2-A, 2-B, 2-C, 2-F. is there.

〔Purpose〕

The present invention has been made in view of the above technical problem, and has as its object to provide an image sensor and an information processing apparatus that can obtain a photoelectric conversion output that is superior to the related art.

It is another object of the present invention to provide an image sensor having a simple configuration capable of obtaining a uniform transmitted signal including a joint portion between optical sensor chips.

[Means for solving the problem]

An object of the present invention is to provide a contact type image sensor in which a plurality of sensor chips having a plurality of pixels arranged in the main scanning direction are arranged in the main scanning direction. This is achieved by an image sensor wherein the reading width is constant and the size of the pixel located at the end of the sensor chip is larger than the size of the other pixels.

[Action]

According to the present invention, the light-receiving area of the pixel at the end is increased by making the read width of the pixel at the end in the sub-scanning direction longer than the read width of the other pixel in the sub-scanning direction. By increasing the output signal, the difference in output signal level from other pixels is corrected.

〔Example〕

FIG. 1 is a drawing that best represents an embodiment of the present invention,
(1) is a line sensor chip in which a plurality of pixels are arranged in the main scanning direction, (2) is a pixel on the line sensor (1) other than the end, and (3) is a pixel at the end. Although only two sensor chips are shown here, the overall configuration is such that five sensor chips are linearly arranged in the main scanning direction as shown in FIG. (4) is a module substrate formed of a ceramic or the like for disposing a line sensor.

In FIG. 1, a plurality of pixels (2), (2) and (3) as a reading section of each line sensor (1) are arranged in the main scanning direction, and the sensor chips are further arranged linearly. As a result, all the pixels are arranged in a straight line.

Although the effective reading width in the main scanning direction of all the pixels in each sensor chip is the same, the reading width a in the sub-scanning direction of the pixel (3) at the end of each sensor chip is the other pixel (2).
Is longer than the reading width a in the sub-scanning direction. Thus, the area of the pixel 3 is larger than the other pixels.

In an image sensor composed of a plurality of line sensors (1), output signals are sequentially read in the main scanning direction from the leftmost pixel of the leftmost sensor shown in FIG.

In this way, by increasing the reading width of the pixel at the end in the sub-scanning direction compared to the width of the other pixels, the pixel area is increased,
The output level of a pixel whose output is small due to the presence at the end is increased. Therefore, an output that is substantially equal to a signal component due to a phenomenon such as a crosstalk component that occurs inevitably in other pixels is added, so that it is possible to obtain an output in which the signal level difference from other pixels is corrected. it can.

In this embodiment, a light-shielding layer made of Al or the like is provided on the light-receiving surface on which the phototransistor is formed, and the size of each pixel is defined by the opening formed in the light-shielding layer.

FIG. 5 shows the light shielding layer. Here, an opening defining a pixel is defined by a first light-shielding layer LS1 and a second light-shielding layer LS2, and the openings are not in a closed shape but communicate with each other.

Of course, a closed opening may be formed by one light shielding layer.

Next, the photoelectric conversion operation according to the present embodiment will be described for one pixel.

 FIG. 6 is a circuit configuration diagram of one pixel of this example.

PS do reset connected bipolar transistors, SW ₁ is NMOS transistor as switch means for performing reset to connect the emitter to a reference voltage source V _ES, SW ₂ is the base to a reference voltage source V _BB which form a pixel PMOS transistor as switch means for, SW ₃ are NMOS transistors as switch means for signal charge transfer, CT is a capacitive load that is generated in the signal voltage.

 The operation will be briefly described.

<Reset operation> First PMOS transistor SW ₂ negative pulse voltage is applied to the gate of the base is clamped to the voltage V _BB.

Then NMOS gate of the transistor SW ₁ positive pulse voltage is applied emitter is connected to the voltage source V _ES, a current flows between the base and the emitter, the light generation carrier disappears remaining on the base.

<Accumulation Operation> Both the NMOS transistors SW ₁ and SW ₃ are turned off, the emitter and the base are both in a floating state, and the accumulation operation is started.

<Reading operation> Next NMOS gate of the transistor SW ₃ positive pulse voltage is applied to turn on, the signal voltage is read to the capacitor CT is connected to the emitter and the capacitor CT.

The basic structure of such an image sensor is disclosed in U.S. Pat. No. 4,686,554 issued to the inventors Omi and Tanaka, and is described in U.S. Pat. It is described as a sensitive, low nozzle photoelectric conversion device.

The image sensor as shown in FIG. 2 is assembled integrally with a light source such as an LED array and an imaging optical system such as a short focus imaging element array in a housing made of Al or the like to form a contact type image. Construct the sensor unit.

[Other embodiments]

Another embodiment of the present invention will be described with reference to FIG.

A plurality of pixels (2) of each line sensor chip,
(2), (2), and (3) are linearly arranged with a pitch P equal to the main scanning direction. Further, the sensor chips are arranged such that the ends of the line sensor chips also have a pitch equal to the pitch P of the other pixel (2). The reading width a ′ in the sub-scanning direction of the end pixel (3) is longer than the reading width a of the other pixels in the sub-scanning direction. The reading widths of the pixels in the main scanning direction are all the same width b. As a result, as in the previous embodiment, the output signals of the end pixel and the other pixels are aligned. In addition, loss of image information is prevented at the connection between the line sensor chips, and a good output signal can be obtained.

The basic configuration is the same as that of the first embodiment except that the pitches of all the pixels are fixed.

In the first and second embodiments described above, a charge storage and amplification type image sensor using a bipolar transistor has been described. However, in the present invention, a photodiode is used as a light receiving unit.
The present invention can be preferably applied to a sensor of a type that transfers signal charges by a MOS switch, a charge-coupled device (CCD), or the like.

FIG. 7 shows an example of a facsimile having a communication function as an image information processing apparatus configured using the sensor unit according to the present embodiment. Here, reference numeral 102 denotes a feeding roller as feeding means for feeding the document 6 toward the reading position;
Reference numeral 104 denotes a separation piece for reliably separating and feeding the originals 6 one by one. Reference numeral 106 denotes a platen roller provided at a reading position with respect to the sensor unit to regulate the surface to be read of the original 6 and to transport the original 6.

P is a recording medium in the form of a roll paper in the illustrated example, and image information read by a sensor unit or, in the case of a facsimile apparatus or the like, image information transmitted from the outside is reproduced here. Reference numeral 110 denotes a recording head as recording means for performing the image formation, 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 112 denotes a platen roller as transporting means for transporting the recording medium P to a recording position by the recording head 110 and regulating the recording surface.

Reference numeral 120 denotes an operation panel provided with a switch or a message for receiving an operation input as input / output means and a display unit for notifying the state of the apparatus.

Reference numeral 130 denotes a system control board as control means, which controls each unit.
In addition, a driving circuit (driver) for the photoelectric conversion element, a processing unit (processor) for image information, a transmission / reception unit, and the like are provided.
140 is a power supply of the apparatus.

As the recording means used in the information processing apparatus of the present invention, it is preferable to use a recording means whose typical configuration and principle are disclosed in, for example, US Pat. Nos. 4,723,129 and 4,740,796. According to this method, at least one of the electrothermal transducers corresponding to recording information and having a rapid temperature rise exceeding nucleate boiling is provided to an electrothermal transducer arranged corresponding to a sheet or a liquid path holding a liquid (ink). By applying a drive signal, the heat generating element generates heat energy,
This is effective because film boiling occurs on the heat-acting surface of the recording head, and as a result bubbles in liquid (ink) can be formed in one-to-one correspondence with this drive signal. 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, the length is determined by a combination of a plurality of recording heads as disclosed in the above specification. Either a configuration that satisfies the condition or a configuration as a single recording head formed integrally may be used.

In addition, a replaceable chip-type recording head that can be electrically connected to the device main body and supplied with ink from the device main body by being attached to the device main body, or an ink tank integrated with the recording head itself The present invention is also effective when a cartridge type recording head provided in the above is used.

〔The invention's effect〕

As described above, by increasing the reading width of the pixel at the end of the line sensor in the sub-scanning direction, the difference in the level of the output signal from another pixel due to the difference in the amount of crosstalk from an adjacent pixel is reduced. This has the effect that correction can be made without raising.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing an enlarged part of the image sensor according to the first embodiment of the present invention, FIG. 2 is a schematic plan view of the image sensor according to the first embodiment, and FIG. FIG. 4 is a schematic plan view showing an enlarged part of the image sensor according to the second embodiment, FIG. 4 is a schematic plan view for explaining a conventional image sensor, and FIG. FIG. 6 is a circuit diagram of one pixel of an image sensor according to the present invention, and FIG. 7 is a schematic diagram for explaining an information processing apparatus according to the present invention. 1 ... sensor chip 2 ... pixel 3 ... end pixel

Claims (8)

(57) [Claims] In a contact type image sensor in which a plurality of sensor chips having a plurality of pixels arranged in the main scanning direction are arranged in the main scanning direction, reading of all pixels in the sensor chips adjacent to each other in the main scanning direction is performed. An image sensor wherein the width is constant and the size of a pixel located at the end of the sensor chip is larger than the size of other pixels. 2. The image sensor according to claim 1, wherein all of the pixels are arranged in the same pitch. 3. The image sensor according to claim 1, wherein said sensor chip has pixels formed by an amplification type optical sensor. 4. The image sensor according to claim 1, wherein said sensor chip has pixels formed by photodiodes, and is provided with a charge-coupled device for transferring signal charges. 5. The sensor chip according to claim 1, wherein a pixel is formed in the bipolar transistor, an output circuit including a capacitive load is provided in an emitter of the bipolar transistor, and a photoelectrically converted signal is read as a voltage in the capacitive load. The image sensor according to claim 1, wherein: 6. An image sensor according to claim 1,
An information processing apparatus comprising: document holding means for holding a document at a reading position by the image sensor. 7. The information processing apparatus according to claim 6, wherein said information processing apparatus has a recording unit for recording image information. 8. The information processing apparatus according to claim 7, wherein said recording means is a recording head which performs recording by discharging ink using thermal energy.