JPH10229476A - Reading device and linear line sensor used for the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve image resolution in the vertical scanning direction by setting a ratio of width at a value smaller than a specific ratio between the arrangement direction of a photoelectric conversion part and the direction orthogonal to the arrangement direction with regard to the shape of an opening part of a photodiode that forms the photoelectric conversion part and accordingly reducing an area, which is exposed with overlapping secured to the pixel adjacent in the vertical scanning direction. SOLUTION: A linear line sensor 100 includes the charge transfer analog shift registers 140 and 150, which are arranged at both sides of a center photoelectric conversion part 110. The part of a luminous flux that is reflected on an original and incident on every part 110 forms a pixel. The adjacent pixels are separated from each other by means of a channel stop, consisting of an aluminum light-shielding curtain, to form an opening part of the part 110 which is long in the arrangement direction of the part 110. Then the ratio is set at <=1/2 between the width of the arrangement direction of the part 110 and that of the direction orthogonal to the arrangement direction with regard to the shape of the opening part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a reader for reading a two-dimensional image and a linear line sensor used for the reader.

[0002]

2. Description of the Related Art FIG. 8 is a device configuration diagram of a 2160 pixel linear line sensor.

The photoelectric conversion unit 110 is a pn photodiode array which is a photoelectric conversion element. In addition to 2160 pixels (S1 to S2160) for outputting an effective signal as shown in FIG. D39), 11 behind
There are pixels (D40 to D50). D13 to D36
Since the photodiode is covered with a light-shielding film, it does not respond to light and is used as a black reference pixel for detecting an output when dark. D0 to D12 correspond to the idle feeding portion, and there are actually no pixels, but there are registers for connecting the transfer portion and the output portion.

On both sides of the photoelectric conversion unit 110, an analog shift register 140 and an analog shift register 150 corresponding to a transfer unit are arranged as shown in FIG. A shift gate 120 is arranged between the photoelectric conversion unit 110 and the analog shift register 140, and a shift gate 13 is provided between the photoelectric conversion unit 110 and the analog shift register 150.
0 is arrayed. Given start clock phi _T to the shift gate 120 and the shift gate 130. Shift gate 120 and the shift gate 130 in response to a start clock phi _T, respectively, the even-numbered analog shift register 140 and the analog shift the charge and odd charges accumulated in the photoelectric conversion element accumulated in the photoelectric conversion element Transfer to the register 150 respectively. Analog shift register 140 and analog shift register 150
Are supplied with shift clocks φ ₁ and φ ₂ (clocks obtained by inverting φ ₁ ). The analog shift register 140 and the analog shift register 150 store the shift clock φ ₁
And in response shifting the charge to the shift clock phi _2. The outputs of the analog shift register 140 and the analog shift register 150 are supplied to an output buffer 160, and after being combined, current amplification is performed to output an image signal V _OUT .

[0005] Note that the output buffer 160 is supplied with a reset clock phi _R. Charges accumulated in the output buffer 160 is reset in response to a reset clock phi _R.

FIG. 9 is a time chart showing the operation of the 2160 pixel linear line sensor shown in FIG.
9A is a time chart showing a readout gate pulse φ _ROG , and FIG. 9B is a time chart showing a combined clock φ _CLK of the shift clock φ ₁ and the shift clock φ ₂ , and FIG. ) Is a time chart showing V _OUT .

According to the timing chart shown in FIG. 9, the readout gate pulse φ _ROG turns off the readout gate when it is at a high level, and in this state, the analog shift register 140 and the analog shift register 150 respond to the shift clock φ _CLK. Shift the charge. During the output period of one main scanning line, a dummy signal for 33 pixels and 2048
An image signal V _{OUT for} 2087 pixels including an effective image signal for pixels and a dummy signal for 6 pixels is transmitted.

[0008]

However, a reading apparatus to which the above-described linear line sensor is applied has a difference in resolution between main scanning and sub-scanning. This is the photoelectric conversion unit 11
It is related to the shape of the opening corresponding to the pixel shape of 0 and the method of sub-scanning. Specifically, when linear scanning is performed in the sub-scanning direction, an area that is exposed to overlap before and after the sub-scanning line (hereinafter, this is simply referred to as an overlap area).
, The spatial frequency of the sub-scanning approaches the sampling frequency based on the pixel pitch in order to produce the same effect as the case where the low-pass filter is inserted in the sub-scanning direction (hereinafter simply referred to as a filter effect). As the signal amplitude decreases, the resolution deteriorates and the fine line reproducibility deteriorates.

FIG. 10 is a schematic diagram showing a structure between pixels of a general linear line sensor.

In the linear line sensor, two adjacent pixels in the photoelectric conversion unit 110 are generally separated from each other by a region called a channel stop. As shown in FIG. The aperture shape of the sensor is determined by the operation performed by the aluminum light shield curtain. Further, in the opening shape of the photoelectric conversion element, the width of the photoelectric conversion element in the arrangement direction is larger than the width orthogonal to the arrangement direction. The relationship between the aperture shape of the photoelectric conversion element and the sub-scanning method described below causes a reduction in the resolution in the sub-scanning direction.

As a sub-scanning method, a case in which reading and scanning are performed with reference to the pixel center or the pixel front end of the linear line sensor can be considered.

FIG. 11 is a conceptual diagram showing a relationship between a filter effect and an output signal when scanning is performed with reference to the pixel center of a conventional linear line sensor. FIG. 11A is a schematic diagram showing an input light image. FIG. 11B is a schematic diagram illustrating pixels of a document, and FIG. 11C is a schematic diagram illustrating an image signal V _OUT output from a linear line sensor.

If the exposure is performed for a time corresponding to the length of the pixel of the original image shown in FIG. 11B, the opening shape of the photoelectric conversion unit 110 has a two-dimensional area as described above. As shown in FIG. 11A, it can be seen that an area to be exposed overlaps before and after the sub-scanning line for a period corresponding to the width orthogonal to the arrangement direction of the photoelectric conversion elements. Accordingly, since the image signal V _OUT output from the linear line sensor is a signal having a level corresponding to the average value of the adjacent pixels, for example, when a white pixel and a black pixel are adjacent to a document pixel, Since a signal level corresponding to the average value of one black pixel and one white pixel is output, no amplitude is generated due to a so-called filter effect. Therefore, when reading and scanning are performed with reference to the pixel center of the linear line sensor, when the black pixels and the white pixels of the document image are adjacent to each other, the resolution in the sub-scanning direction is reduced.

FIG. 12 is a conceptual diagram showing a relationship between a filter effect and an output signal when reading and scanning are performed with reference to a pixel front end of a conventional linear line sensor. FIG. 12A is a schematic diagram showing an input light image. FIG. 12B is a schematic diagram illustrating pixels of a document, and FIG. 12C is a schematic diagram illustrating an image signal V _OUT output from a linear line sensor. For the same reason as described with reference to FIG. 11, even when scanning is performed with reference to the pixel front end of the linear line sensor, if the black pixels and the white pixels of the original image are adjacent to each other, the reduction in the resolution in the sub-scanning direction is reduced. Had occurred.

In view of the above technical problems, an object of the present invention is to provide
It is an object of the present invention to provide a reading apparatus and a linear line sensor that can improve the resolution in the sub-scanning direction by reducing an area exposed to overlap with an adjacent pixel.

[0016]

The above object is achieved by the following constitution.

(1) A light source for irradiating a subject with light, an optical system for converging reflected light from the subject, and a plurality of photoelectric conversion elements for converting incident light converged by the optical system into electric charges are linear. A photoelectric conversion unit disposed on both sides of the photoelectric conversion unit along the direction of arrangement of the photoelectric conversion unit, and a transfer unit for reading and transferring the charge from the photoelectric conversion unit, the reading device, A reading device, wherein the shape of the opening of the conversion unit is a rectangle that is long in the arrangement direction of the photoelectric conversion units.

(2) The opening shape of the photoelectric conversion unit for converting incident light into electric charge is such that the ratio of the width of the photoelectric conversion unit in the arrangement direction to the width orthogonal to the arrangement direction is 1/2 or less. Linear line sensor.

(3) A light source for irradiating a subject with light, an optical system for converging reflected light from the subject, and a photoelectric conversion element for converting incident light converged by the optical system into electric charges are linearly arranged. A photoelectric conversion unit, a reading device including a transfer unit disposed on both sides of the photoelectric conversion unit along the direction of arrangement of the photoelectric conversion unit and reading and transferring the charge from the photoelectric conversion unit. An electronic shutter for controlling an accumulation time of the photoelectric conversion unit independently of a read time, and an exposure time in one line is set to half or less of a one line period.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) A schematic configuration of a reading apparatus according to the present embodiment will be described.

FIG. 1 is a sectional view showing a reading apparatus using a linear line sensor according to the present embodiment.

In FIG. 1, a document 6 is conveyed on a carriage 9 by rollers 7 and 8. At this time, the light source 1
The light from 0 irradiates the original 6. The reflected light from the original 6 is reflected by the mirrors 11 and 12, guided to the lens 13, and converged on the linear line sensor. In this state, the linear line sensor 100 converts the image of the document 6 into an image signal.

A hood 14 provided near the light irradiating portion of the original 6
Is for preventing disturbance light.

The slit plate 15 has a narrow slit. The slit is arranged so as to be located on the path of the reflected light from the document 6. With this, manuscript 6
The width of the luminous flux converged on the linear line sensor 100 after the reflected light from the lens is narrowed is made smaller than the chip width of the linear line sensor 100. In this way,
The image is projected on the linear line sensor 100.

FIG. 2 is a sectional view of the linear line sensor according to the present embodiment.

In FIG. 2, a linear line sensor 100 is stored inside a ceramic case 2. The ceramic case 2 is sealed by a glass plate 3 so that dust and the like do not enter inside. In the linear line sensor 100, photoelectric conversion units 110 are arranged at the center thereof, and an analog shift register 140 and an analog shift register 150 for charge transfer are provided on both sides of the photoelectric conversion unit 110.
Are arranged. The width t1 of the photoelectric conversion unit is 10
It is extremely narrow, about μm. On the other hand, the width t of the analog shift register 140 and the analog shift register 150
2, t3 is about 500 μm. Therefore, the chip width of the linear line sensor 100 is about 1 mm.
The analog shift register 140 and the analog shift register 150 are prevented from leaking into the analog shift register 140 and the analog shift register 150 by depositing an aluminum film on the upper surface. As a result, electric charges are not generated in the analog shift register 140 and the analog shift register 150, and the image signals are not adversely affected. Linear line sensor 10
The lead terminal 104 is connected to 0. A clock signal is applied through the lead terminal 104, and the output of the linear line sensor 100 is output from the lead terminal 104 to the outside.

The linear line sensor 100 includes a monochrome linear line sensor and a color linear sensor. Any linear line sensor according to the present embodiment can be used as long as the ratio of the width of the photoelectric conversion unit 110 in the arrangement direction to the width orthogonal to the arrangement direction of the opening of the pn photodiode is 以下 or less. Is also good.

FIGS. 3 and 4 are schematic views showing the openings of the linear line sensor according to the present embodiment.

In the linear line sensor 100, since the effective sensor aperture is determined by the channel stop as shown in FIG. 3, the width of the channel stop is set to 2 μm, for example, in the arrangement direction of the photoelectric conversion units 110 of 5 μm × 2 μm. A long opening or separation between pixels is performed by a channel stop and a light-shielding aluminum electrode as shown in FIG. 4 so that the shape of the opening of the photoelectric conversion unit is changed in the direction of arrangement of the photoelectric conversion unit 110 of 7 μm × 2 μm. It is a long rectangle.

The resolution of the image signal in the sub-scanning direction obtained from the reading apparatus according to the present embodiment will be described with reference to FIG.

FIG. 5 is a conceptual diagram showing the relationship between the filter effect and the output signal V _OUT when scanning is performed with reference to the pixel center of the linear line sensor in this embodiment.

FIG. 5A is a schematic diagram showing an input light image, FIG. 5B is a schematic diagram showing pixels of a document, and FIG. FIG. 4 is a schematic diagram showing an image signal V _OUT .

Even when the exposure is performed for a time corresponding to the length of the pixel of the original image shown in FIG. 5B, the shape of the opening of the photoelectric conversion unit is changed as described with reference to FIGS. 7 μm × 2
As shown in FIG. 5 (a), since the rectangular shape is long in the array direction of the photoelectric conversion units 110, it overlaps before and after the sub-scanning line for a period corresponding to the width orthogonal to the array direction of the photoelectric conversion elements. Even if a region to be exposed occurs, the overlapping region of the adjacent pixels is
2, the average value of one black pixel and one-half white pixel or less is obtained when white pixels and black pixels are adjacent to each other in the document. Is output, so that an amplitude is generated by reducing the so-called filter effect.

Therefore, according to the reading apparatus of the present embodiment, even when reading and scanning are performed with reference to the pixel center of the linear line sensor 100, if black and white pixels of the original image are adjacent to each other, the reading in the sub-scanning direction will be performed. There is no reduction in resolution.

(Embodiment 2) The reading apparatus of this embodiment employs a linear line sensor 200 having an electronic shutter function. Therefore, the shape of the opening of the photoelectric conversion unit of the linear line sensor 200 is different from that of the first embodiment.
As described with reference to FIGS. 3 and 4, the opening does not need to be a rectangular shape long in the arrangement direction of the photoelectric conversion units 110 unlike the linear line sensor 100.

The configuration of the reading apparatus according to the present embodiment is the same as that described with reference to FIGS. 1 and 2 except for the linear line sensor 200.

Here, the device configuration and operation of a linear line sensor having an electronic shutter function will be described with reference to FIG.

FIG. 6 is a conceptual diagram showing the device configuration and operation of a linear line sensor having an electronic shutter function. FIG. 6A is a block diagram of a photoelectric conversion unit having an electronic shutter function. 6 (b) is AA of FIG. 6 (a).
FIG. 6 is a potential diagram at the time of signal charge accumulation in a cross section, and FIG.
FIG. 6C is a potential diagram showing a normal read mode, and FIG. 6D is a potential diagram when an electronic shutter is used.

As shown in FIG. 6A, a linear line sensor 200 having an electronic shutter function includes a shutter drain 210, a shutter gate 220, a photoelectric converter 230, a register gate 240, and an analog shift register 250.
It consists of:

In the normal read mode, as shown in FIG. 6C, the register gate 240 is turned on and the photoelectric conversion unit 23 is turned on.
The stored charge of 0 is transferred to the analog shift register 250.
When the electronic shutter is used, the shutter gate 220 is turned on as shown in FIG.
Is discarded to the shutter drain 210. As described above, the linear line sensor 200 can control the accumulation time independently of the readout gate pulse φ _ROG .

In the present embodiment, the electronic shutter referred to in the claims comprises a shutter gate 220 and a shutter drain 210.

FIG. 7 is a time chart when the accumulation time is controlled independently of the read gate pulse φ _ROG by focusing on one photoelectric conversion element. The relationship between the filter effect and the output signal is shown.

FIG. 7A is a time chart showing the state of the read gate pulse φ _ROG . Register gate 2 when readout gate pulse φ _ROG is at high level
40 is turned off, and the electric charge is shifted to the analog shift register 250 in response to the shift clocks φ ₁ and φ ₂ .

FIG. 7B shows an electronic shutter gate pulse φ.
₆ is a time chart showing a state of _SHUT . If the electronic shutter gate pulse φ _SHUT is at a high level, the shutter gate 220 is turned off and the electronic shutter function is not _{activated.If the} electronic shutter gate pulse φ _SHUT is at a low level, the shutter gate 220 is opened. The charge stored in the photoelectric conversion unit is discarded by the shutter drain 210.

FIG. 7C shows the amount of charge stored in the photoelectric conversion unit. The amount of accumulated charges increases in proportion to time in a state where a constant amount of light is applied to the photoelectric conversion unit. However, in this embodiment, as shown in FIG. 7B, the electronic shutter gate pulse φ _SHUT is turned off near the middle of the exposure period of one pixel in the sub-scanning direction, so that the electronic shutter gate pulse φ _SHUT Before the OFF state, the photoelectric conversion unit 2
30 is discarded to the shutter drain 210, the electric charge accumulated after the electronic shutter gate pulse φ _SHUT is turned off becomes the image signal V.
_OUT .

FIG. 7D is a schematic diagram showing an input light image, FIG. 7E is a schematic diagram showing pixels of a document, and FIG. FIG. 4 is a schematic diagram showing an image signal V _OUT .

The output of the analog shift register 250 is
As shown in FIG. 7 (f), the image signal V _OUT is _supplied to the output buffer 160, amplified, combined, and output.

As shown in FIG. 7 (d), even if an area to be exposed overlaps with the adjacent pixel n + 1 occurs, the overlap area of the adjacent pixel is smaller than that of the related art shown in FIGS. For example, when a white pixel and a black pixel are adjacent to each other on a document, a signal level corresponding to the average value of one black pixel and one-half of the white pixels is output. (See FIG. 7 (f)), so that the amplitude is generated by reducing the so-called filter effect.

Therefore, when the reading apparatus of the present embodiment is used, even when scanning is performed with reference to the front end of the pixel of the linear line sensor 200, if the black pixels and the white pixels of the original image are adjacent to each other, the scanning in the sub-scanning direction is performed. There is no reduction in resolution.

[0050]

According to the first or third aspect of the present invention,
By providing the above configuration, it was possible to provide a reading device capable of reducing the area exposed to overlap with adjacent pixels and improving the resolution in the sub-scanning direction.

According to a second aspect of the present invention, there is provided a linear line sensor capable of improving the resolving power in the sub-scanning direction by reducing the area exposed by overlapping with adjacent pixels by providing the above-mentioned configuration. Was completed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a reading apparatus using a linear line sensor according to an embodiment.

FIG. 2 is a cross-sectional view of the linear line sensor according to the embodiment.

FIG. 3 is a schematic diagram showing an opening of the linear line sensor according to the embodiment.

FIG. 4 is a schematic diagram showing an opening of the linear line sensor according to the embodiment.

FIG. 5 is a conceptual diagram showing a relationship between a filter effect and an output signal when scanning is performed with reference to the pixel center of the linear line sensor according to the embodiment.

FIG. 6 is a conceptual diagram showing a device configuration and operation of a linear line sensor having an electronic shutter function.

FIG. 7 is a time chart when the accumulation time is controlled independently of the read gate pulse φ _ROG by focusing on one photoelectric conversion element.

FIG. 8 is a device configuration diagram of a 2160-pixel linear line sensor.

9 is a time chart showing the operation of the 2160-pixel linear line sensor shown in FIG.

FIG. 10 is a schematic diagram showing a structure between pixels of a general linear line sensor.

FIG. 11 is a conceptual diagram showing a relationship between a filter effect and an output signal when scanning is performed with reference to a pixel center of a conventional linear line sensor.

FIG. 12 is a conceptual diagram illustrating a relationship between a filter effect and an output signal when scanning is performed with reference to a pixel front end of a conventional linear line sensor.

[Explanation of symbols]

 6 Document 10 Light source 11, 12 Mirror 13 Lens 100 Linear line sensor 110, 230 Photoelectric converter 120, 130 Shift gate 140, 150, 250 Analog shift register 210 Shutter drain 220 Shutter gate 240 Register gate

Claims (3)

[Claims] A light source for irradiating a subject with light, an optical system for converging reflected light from the subject, and a plurality of photoelectric conversion elements for converting incident light converged by the optical system into electric charges are linearly arranged. In the reading device including a photoelectric conversion unit to be arranged, a transfer unit arranged on both sides of the photoelectric conversion unit along the arrangement direction of the photoelectric conversion unit, and reading and transferring the charge from the photoelectric conversion unit, A reading device, wherein the shape of the opening is a rectangle that is long in the arrangement direction of the photoelectric conversion units. 2. A photoelectric conversion unit for converting incident light into electric charges, wherein an opening shape of the photoelectric conversion element has a ratio of a width of the photoelectric conversion element in an arrangement direction to a width orthogonal to the arrangement direction of 1/2 or less. Linear line sensor. 3. A light source for irradiating a subject with light, an optical system for converging light reflected from the subject, and a plurality of photoelectric conversion elements for converting incident light converged by the optical system into electric charges are linearly arranged. A reading device including a photoelectric conversion unit to be disposed, a transfer unit disposed on both sides of the photoelectric conversion unit along the arrangement direction of the photoelectric conversion unit, and reading and transferring the charge from the photoelectric conversion unit; An electronic shutter for controlling an accumulation time of the photoelectric conversion unit independently of time, and an exposure time in one line is set to 以下 or less of one line period.