JPH06163979A - Photoelectric transducer - Google Patents

Abstract

PURPOSE:To improve the S/N ratio at the connection part of a sensor chip, and exclude the difference of output offset, by installing point light sources arranged so as to form a region of high light intensity distribution on the connection position of the sensor chip. CONSTITUTION:Five line sensor chips are arranged in line in the main scanning direction. A module substrate 8 is formed of ceramic or the like, in order to arrange the line sensor chips. The relation to a sensor output signal 9 is so shown that positional relations in the X-direction of point light sources 7, sensors, and the sensor output become identical. The point light sources 7 are so arranged that the density of the point light sources 7 on a substrate 74 for light sources which substrate is formed of epoxy glass becomes high. Thereby the S/N ratio on chip connection parts 10 is always increased, and the noise on the chip connection position at the time of white correction is relatively suppressed as compared with the noise of the other parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion device which can be used in facsimile machines, copying machines, scanners and the like.

More specifically, the present invention relates to a photoelectric conversion device using a so-called multi-chip type image sensor in which a plurality of image sensor chips formed by arranging a plurality of photoelectric conversion elements are arranged on a substrate. .

[0003]

2. Description of the Related Art Conventionally, a linear image sensor constructed by arranging read pixels in a straight line has been widely used in image reading apparatuses such as facsimiles and scanners. Since this type of linear image sensor is formed on a silicon wafer, its sensor length is limited by the wafer size, and it is difficult to form a linear image sensor chip having the same length as the original read by the image reading device. Is.

For this reason, conventionally, an image is read by reducing the reflected light from the original using an optical system and performing reduction projection on a linear image sensor. However, in an image reading apparatus using such a reduction optical system, a large space for disposing the optical system must be taken and the resolution is not good. Then, in order to solve this, JP-A-60-1276
No. 0, etc. propose a so-called multi-chip type image sensor (contact image sensor) in which a plurality of linear image sensor chips are arranged in a straight line.

FIG. 4 shows a photoelectric conversion portion of such a multi-chip type image sensor. This drawing corresponds to a plan view, and 3 is a line sensor chip. Here, five lines are arranged linearly in the main scanning direction. Reference numeral 8 is a module substrate made of ceramic or the like for disposing the line sensor chip 3.

Such a multi-chip type sensor has a drawback in that the output sensitivity and offset are different for each sensor chip due to variations in characteristics of each sensor chip. In particular, the difference in output offset between the sensor chips appears as a difference in image density depending on the width of the chip due to the difference in gradation.

As a result, on the joints of the chips (1 in FIG. 4).
In 0), streaks are apparently generated due to the difference in lightness and darkness of the image, which is likely to cause a problem in image quality.

FIG. 5 is a schematic diagram of an optical system used in the above-mentioned multichip type image sensor. In this figure, 7 is an array light source in which point light sources are linearly arranged. Here, 71, 72, 73 are respectively the first, second, and
A third point light source is shown. Reference numeral 74 is a substrate formed of glass epoxy or the like and having a circuit for driving a point light source.

The reflected light from the original 5 obtained by the irradiation light from these point light sources is supplied to each pixel 31 of the sensor chip 3 by an appropriate image forming means 4 (for example, a cylindrical lens array).
It is imaged on the top and read out as a sensor output.

The light source used in FIG. 5 has a variation in the amount of light for each point light source forming the array light source 7, and that each point light source exists discretely in the sensor main scanning direction. It has a drawback that it causes unevenness in light amount.

FIG. 6 shows the light intensity distribution on the original surface illuminated by such a point light source. The nonuniformity of the light intensity of the point light source has the same meaning as the nonuniformity of the sensitivity of each pixel and affects the image quality. Therefore, white correction processing (shading correction processing) that eliminates such sensitivity unevenness is often used together.

FIG. 7 is a diagram for explaining such shading correction. In the figure, 11 is a signal output before correction when the white reference plate is read, and 12 is a 100% signal output (white reference) after correction by this signal. Further, G ₁ and G ₂ are correction coefficients that are multiplied by the read data at the time of correction at points A and B, respectively. Here, when noise of the same magnitude exists at both points A and B before correction (the S / N ratio is naturally lower at point B), the noise at point B after correction is G _{2 at} point A. / G amplified ₁ times.

FIG. 8 is a diagram showing the relationship between the multi-chip type image sensor shown in FIG. 4, the sensor output signal thereof, and the array light source. Here, 9 represents the sensor output signal when the white reference plate is read.

Prior Art 2 As described above, a contact type in which a sensor array is used as a document reading device used in a facsimile, a copying machine, a scanner or the like, a read image is formed in a one-to-one manner, and the same size as the read document is read. Image sensors are known.

FIG. 11 shows a plan view (A) and a side view (B) of this contact image sensor. The illustrated contact-type image sensor is composed of a sensor array, a short-focus image forming element array, a light source (not shown), a cover glass 103 for holding a moving original, and other parts. These members are housed inside the frame 104.

In such a document reading apparatus, a power supply and signals for driving the document reading apparatus as well as a connecting mechanism component 110 for input / output of output signals from the document reading apparatus are used.

[0017]

Problem 1 However, in the conventional example shown in FIG. 8, the interval (cycle) between the joints of the sensor chips 3 and the interval (cycle) between the point light sources.
Since there is no correlation between, there is a possibility that an area with a small amount of light may come to the chip joint position.

That is, when there is a joint position of the sensor chips in a region where the light amount is low, such as point C shown in FIG. 8, as described with reference to FIG. It will be amplified by the gain of.

As a result, the "streak" at the chip joint position, which is easily noticeable in image quality, is further emphasized.

Such image quality deterioration becomes a particular problem when the gradation of the sensor is increased.

Therefore, in view of the above points, a first object of the present invention is to provide a photoelectric conversion device configured to increase the S / N ratio at the joint portion of the sensor chip to eliminate the difference in output offset. is there.

Problem 2 In the conventional example shown in FIG. 11, a power source and signals for driving the document reading device, and a connecting mechanism component 110 for inputting and outputting an output signal from the document reading device are provided.
In order to hold the original reading apparatus main body, a board 120 for fixing the connecting mechanism component 110, a screw 130 for fixing these, and the like are required.

Further, since the connection mechanism part 110 is held at the outermost part of the document reading device, stray noise is superimposed on the power source and signals for driving the document reading device and further on the output signal from the document reading device. There is a problem.

Therefore, a second object of the present invention is to provide a photoelectric conversion device which has a simplified mechanism for electrical connection to the outside and is excellent in noise resistance.

[0025]

To achieve the first object of the means 1 the invention SUMMARY OF THE INVENTION The present invention provides a photoelectric conversion apparatus having a multi-chip type image sensor formed by arranging a plurality of sensor chips, wherein The point light source is arranged so as to form a region having a high light intensity distribution on the joint position of the sensor chip.

Here, the arrangement period of the point light sources is 1 / n times (n = 1, 2, 3 ...) The arrangement period of the sensor chips.
The period is preferable.

Of the point light sources, the point light source corresponding to the joint position of the sensor chip may be one having a higher light intensity than other point light sources.

Means 2 In order to achieve the second object of the present invention, the present invention is to mount a plurality of sensor chips in a photoelectric conversion device provided with a multi-chip type image sensor in which a plurality of sensor chips are arranged. The sensor array substrate is provided at one end with a connection mechanism section for electrical connection.

Here, the connection mechanism portion has a metal piece printed and printed on a printed circuit board, and holds the metal piece to establish an electrical connection with the outside.

[0030]

Operation 1 According to the above configuration (means 1) of the present invention, by arranging the point light sources so that a region having a high light intensity distribution is formed on the sensor chip joint position of the multi-chip image sensor, the sensor chip is arranged. Increase the S / N ratio at the joint,
It is possible to make the difference in output offset between chips, which is a problem in image quality, inconspicuous.

Function 2 According to the above-mentioned structure (means) of the present invention, not only the board and screw for fixing the electrical connection mechanism component (connector) to the apparatus main body are not required, but also the sensor on the sensor array board is provided. Since it is possible to make electrical connection with the chip in the shortest distance, it is possible to prevent noise from being superimposed on the signal line and the like.

[0032]

EXAMPLES Examples of the present invention will be described in detail below.

Embodiment 1 FIG. 1 shows a multi-chip type image sensor according to a first embodiment of the present invention. In the figure, 3 is a line sensor chip, and here five line sensor chips are arranged linearly in the main scanning direction. Reference numeral 8 is a module substrate made of ceramic or the like for disposing the line sensor chip 3.
Reference numeral 7 is a point light source, and 74 is a light source substrate made of glass epoxy or the like. 9 is a sensor output signal. Here, the positional relationship of the point light source, the sensor, and the sensor output in the x direction is shown to be the same.

In this embodiment, the point light sources are arranged in the chip joint 10 so that the density of the point light sources on the substrate 74 is high. As a result, the S / N ratio on the chip joint 10 is always high, and the noise on the chip joint position during white correction is relatively suppressed as compared to the noise of other portions.

Embodiment 2 FIG. 2 shows a multi-chip type image sensor according to a second embodiment of the present invention. In this embodiment, the point light sources are arranged at regular intervals, and the cycle thereof is 1 / n of the cycle of the sensor chip.
The period is doubled (n = 1, 2 ...) And the point light sources are arranged so as to come to the chip joint positions. Other configurations are the same as those in the first embodiment.

As a result, the amount of light is always high on the chip joint position, so that the influence of noise at the chip joint position is reduced as compared with the case where the light source is placed at the same position as the chip joint position. The image quality is improved.

Embodiment 3 FIG. 3 shows a multi-chip type image sensor according to a third embodiment of the present invention. In this embodiment, the point light source is 7
Two types of light sources, 5 and 76, are used. Here, the point light source 75 has a higher light intensity than 76.

The period of the point light source is 1 / n times the period of the sensor chip (n = 1, 2 ...), except that the position of the point light source 75 is aligned with the joint position of the chip. The configuration is the same as in Example 2. As a result, the signal component at the chip joint is further increased, and the S / N ratio of the chip joint is further improved.

Embodiment 4 FIG. 9 shows a multi-chip type image sensor according to a fourth embodiment of the present invention. FIG. 3A is a plan view of the image sensor, and FIG. 1B is a side view thereof.

In the figure, reference numeral 100 denotes a connection mechanism portion, which is provided with printed wiring at one end of a sensor array substrate for mounting a sensor chip. Further, 103 is a cover glass for protecting the sensor chip, and 104 is a frame for housing the sensor array substrate.

The connection mechanism section 100 shown in FIG. 9 holds the printed circuit board and is combined with a connector (not shown) having electric contacts to supply power from the outside and signal connection with the outside. It can be done directly. That is, since the connection cord and the connector for connecting the external device and the photoelectric conversion device are unnecessary,
It is also effective in preventing the superposition of noise.

Embodiment 5 FIG. 10 shows a multi-chip image sensor according to a fifth embodiment of the present invention. The present embodiment differs from the fourth embodiment only in that the connection mechanism portion 200 with the outside is projected downward in the drawing. That is, there is no difference in that the connection mechanism portion is integrally formed at one end of the sensor array substrate.

[0043]

EFFECTS one invention, according to the present invention (unit 1), the high light intensity distribution region arranged point light sources to occur on the chip joint positions of a multi-chip type image sensor, S / N in the chip joint Since the ratio is improved, the image quality and the gradation can be improved during the white correction without increasing the manufacturing cost or changing the structure.

Effect 2 According to the present invention (Means 2), since the connection mechanism portion can be integrally formed at one end of the sensor array substrate, not only the connector, the connection cord, the screw and the like are not required, but also the noise is generated. It is possible to suppress the overlap.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a second embodiment of the present invention.

FIG. 3 is a schematic diagram showing a third embodiment of the present invention.

FIG. 4 is a plan view showing a photoelectric conversion unit of a multi-chip image sensor.

FIG. 5 is a schematic diagram showing an optical system of a multi-chip image sensor.

6 is a diagram showing a light intensity distribution by the point light source shown in FIG.

FIG. 7 is an explanatory diagram of shading correction.

FIG. 8 is a schematic view showing a conventional example.

FIG. 9 is a schematic view showing a fourth embodiment of the present invention.

FIG. 10 is a schematic view showing a fifth embodiment of the present invention.

FIG. 11 is an external view of a document reading device in a conventional example.

[Explanation of symbols]

 3 Sensor Chip 5 Original 7 Array Light Source 8 Module Board 9 Sensor Output Signal 10 Chip Joint 11 Sensor Output Before White Correction 12 Sensor Output After White Correction 31 Sensor Pixels 51 Original Surface 71, 72, 73 Point Light Source 74 For Point Light Source Substrate 75 Point light source (light intensity: high) 76 Point light source (light intensity: small) 100 Connection mechanism section 103 Cover glass 104 Frame 110 Connection mechanism parts 120 Substrate 130 Screw 200 Connection mechanism section

Claims (5)

[Claims] 1. A photoelectric conversion device comprising a multi-chip type image sensor in which a plurality of sensor chips are arranged, wherein point light sources arranged so as to form a region having a high light intensity distribution on a joint position of the sensor chips. A photoelectric conversion device comprising: 2. The array period of the point light sources according to claim 1, wherein an array period of the sensor chips is 1 / n times (n =
A photoelectric conversion device having a cycle of 1, 2, 3 ...). 3. The point light source according to claim 1, which corresponds to the joint position of the sensor chips among the point light sources,
A photoelectric conversion device using a light source having a higher light intensity than other point light sources. 4. A photoelectric conversion device comprising a multi-chip type image sensor in which a plurality of sensor chips are arranged, and a connection mechanism section for electrically connecting to one end of a sensor array substrate on which the plurality of sensor chips are mounted. A photoelectric conversion device comprising: 5. The connection mechanism unit according to claim 4,
A photoelectric conversion device, comprising: a printed circuit board having a metal piece printed on it; and holding the metal piece to hold the metal piece for electrical connection to the outside.