JPH0865455A - Image reader, image read method and image pickup device - Google Patents

Abstract

PURPOSE: To provide an image reader in which color mixture hardly fakes place even in the case of employing a linear image sensor where light receiving sections of different colors are arranged to have a charge transfer section inbetween. CONSTITUTION: The reader is provided with a linear image sensor that has plural line sensors 101, 102, 103 corresponding to each color, in which no charge transfer section is arranged among plural line sensors, the charge received and stored by a light receiving section 102 of the line sensor is transferred via a light receiving section 103 of a different color to shift the charge to charge transfer sections 106, 107, and the transfer direction of the charge stored in the light receiving section 102 is made coincident in the sub-scanning direction in which a read image is scanned on the linear image sensor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device, an image reading method and an image pickup device, and more particularly to an image reading device and an image reading method using a linear image sensor for performing an intra-pixel transfer read operation.

[0002]

2. Description of the Related Art Hitherto, as a color image reading apparatus using a linear image sensor, a structure shown in FIG. 5 has been proposed. The color image reading apparatus shown in FIG.
10 and the reflection shade 209 to illuminate the reflected light from the document with the first mirror 208, the second mirror 205, and the third mirror 20.
An image is formed on the light receiving surface of the CCD (color linear image sensor) 201 by the lens 6 and the lens 202. Further, by moving the portion indicated by the broken line 207 in FIG. 2 at the speed V in the arrow direction in the drawing and moving the portion indicated by the broken line 203 at the speed V / 2 in the arrow direction in the drawing, the entire image of the original 212 is imaged. Can be read by the CCD 201.

FIG. 6 is a diagram showing a configuration example of a CCD linear image sensor 201 used in a conventional color image reading apparatus. In FIG. 6, 301, 302, 3
Reference numeral 03 is a light receiving portion having R, G, and B color filters, respectively. In this light receiving portion, a diode for converting a photon into an electric charge (electron) is arranged for each pixel. The light received for a predetermined time and the electric charges generated thereby are respectively transferred to the CCD transfer unit (charge transfer unit) for the ODD pixel.
The signals are transferred (shifted) to the CCD transfer units (charge transfer units) 305, 307, 309 for 304, 306, 308 and EVEN pixels. The charges transferred (shifted) to the CCD transfer unit are sequentially transferred in a fixed direction in the CCD transfer unit while the light receiving unit is receiving and accumulating the next line,
The voltage signals are sequentially converted by the amplifiers 310 to 316 and output.

[0004]

However, as shown in FIG. 6, the conventional color linear image sensor has a CCD transfer unit for transferring charge between the R, G and B light receiving units. As shown in Fig. 6, R
It is necessary to set a large gap between the light receiving portions of G and G and a gap between the light receiving portions of G and B.

When the distance between the light receiving portion and the light receiving portion is widened, when performing signal processing such as masking calculation on the read R, G, B signals, a memory for correcting the read positions of R, G, B is required. However, there is a problem in that the larger the R, G, B interval, the larger the required memory capacity.
However, recently, there has been proposed a structure in which the CCD transfer section is not adjacent to the light receiving section, but the light receiving sections of different colors are sandwiched therebetween.

In this case, since it is not necessary to dispose the CCD transfer section between the light receiving sections for the respective colors, it is possible to greatly reduce the distance between the R, G, B light receiving sections as compared with the conventional sensor. On the other hand, on the other hand, the charge received and accumulated is CCD
In order to transfer (shift) to the transfer unit, it is necessary to pass through light receiving units (pixels) of different colors. When so-called intra-pixel transfer is performed, light is emitted even when passing through light-receiving units of different colors, and therefore, there is a problem that a slight color mixture occurs during transfer (shift).

Therefore, the present invention has been made in view of the above problems, and an object thereof is to use a linear image sensor in which a charge transfer section is arranged with light receiving sections of different colors interposed therebetween. An object of the present invention is to provide an image reading device and an image reading method in which color mixing is less likely to occur.

[0008]

In order to solve the above-mentioned problems and achieve the object, the image reading apparatus of the present invention scans the original in the main scanning direction and the sub-scanning direction while irradiating the original with light. In an image reading device for reading a color image by photoelectrically converting the reflected light reflected by using a line sensor, a plurality of the line sensors corresponding to each color are provided, and a charge transfer unit is provided between the plurality of line sensors. In order to shift the electric charge received and accumulated in the light receiving part of the line sensor to the charge transfer part without being arranged, the linear image sensor is configured to pass through the light receiving parts of different colors, and the light receiving part The transfer direction of the accumulated charge is
It is characterized in that the read image coincides with the sub-scanning direction scanned on the linear image sensor.

Further, in the image reading apparatus according to the present invention, the plurality of line sensors are three line sensors provided with color filters corresponding to respective colors of red, green and blue. Further, the image reading method of the present invention scans a document in the main scanning direction and the sub-scanning direction while irradiating it with light, and photoelectrically converts the reflected light reflected from the document using a linear image sensor to form a color image. In the image reading method for reading, a charge transfer unit is not arranged between the light receiving units of the respective colors of the linear image sensor, and light receiving units of different colors are received in order to shift the charges received and accumulated by the light receiving unit to the charge transfer unit. When passing through, the transfer direction of the electric charge accumulated in the light receiving part,
The read image is matched with the sub-scanning direction scanned on the linear image sensor.

The image pickup device of the present invention is arranged in the vicinity of the first line sensor, the second line sensor, and the second line sensor, and charges the first and second line sensors. Transfer means for reading in the main scanning direction, sub-scanning means for relatively sub-scanning the first and second line sensors and the subject, and a charge signal of the first line sensor for the second line It is characterized in that the data is transferred to the transfer means via a sensor, and the transfer direction and the sub-scanning direction by the sub-scanning means are the same direction.

Further, in the image pickup apparatus according to the present invention, the sensitivity of the first line sensor to the second
It is characterized by lowering the sensitivity of the line sensor.

[0012]

Since the image reading device, the image reading method and the image pickup device according to the present invention are configured as described above, when the charges received and accumulated in the light receiving portion are transferred via the light receiving portions of different colors. In addition, by matching the charge transfer direction with the sub-scanning direction in which the image information is scanned on the linear image sensor, as compared with the case where the charges are transferred in the direction opposite to the sub-scanning direction, Since the positions are close to each other, it is possible to reduce the influence of the color mixture on the deterioration of the image quality.

[0013]

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. (First Embodiment) FIG. 1 is a diagram showing a configuration example of a CCD linear image sensor 201 used in a color image reading apparatus according to a first embodiment of the present invention. In the figure, 101, 102, and 103 are R (red) and G, respectively.
It is a light receiving portion having color filters of (green) and B (blue). In this light receiving portion, a diode for converting a photon into an electric charge (electron) is arranged for each pixel. In this linear image sensor, unlike the conventional linear image sensor, the CCD transfer unit is not arranged between the respective light receiving units, so that the distance between the light receiving units can be narrowed. In the figure, the distance between the G and R light receiving portions and the distance between the R and B light receiving portions can be reduced to a distance of 2A, which is about twice as large, where A is the size of one side of the pixel of the light receiving system. It is fully feasible. Therefore, it is possible to set the distance between the light receiving portions to be narrower than that in the conventional case where the CCD image transfer portion is arranged between the light receiving portions to form the linear image sensor, and the distance between the light receiving portions can be set smaller. It is possible to reduce the required read position correction memory capacity.

Further, in the configuration of the first embodiment,
When the charges received and accumulated by the light receiving unit are transferred via the light receiving units of different colors, the direction in which the charges are transferred in the sub-scanning direction matches the direction in which the image information is scanned on the linear image sensor. Is set. In FIG. 1, R
The electric charges received and accumulated by the light receiving section 102 are transferred to the CCD transfer sections 106 and 107 via the B light receiving section 103. Further, the transferred charges are output as R-ODD output and R-EVEN output via the amplifiers 112 and 113. As described above, in this embodiment, the transfer direction of the electric charges in the sub-scanning direction is set from the upper side to the lower side in the figure, that is, so as to coincide with the direction S in which the image information is scanned on the linear image sensor. There is.

Next, when the charges are transferred through the light receiving portions of different colors, the influence of the color mixture caused by the irradiation of light during the transfer depends on the image scanning direction and the charge transfer direction. It will be described below. In FIG. 2, consider a case where the image information shown in (a) is temporally moved in the sub-scanning direction 401. The image information is scanned in the sub-scanning direction 401 while being combined with the light receiving surfaces of the light receiving units 403, 404, and 405 shown in (b). Here, the direction perpendicular to the paper surface is the main scanning direction, which is the direction in which the light receiving portions (pixels) are arranged. The leading edge 409 of the image information is temporally 4 in the sub-scanning direction.
01, the light receiving units 403, 40
4, the changes in the amount of charge generated in (405), (c), (d),
It shows in (e). It is assumed that when the light receiving unit 404 having image information R is scanned, the charge in the hatched portion 407 is integrated and accumulated. At this time, consider a case where the charge is transferred via the light receiving portions of different colors in the direction indicated by arrow 402 which is the opposite direction to the sub-scanning direction 401. The charges accumulated in the R light receiving unit 404 are transferred via the G light receiving unit 403. At this time, since the transfer is performed immediately after the R light receiving unit 404 finishes storing for a certain period, when the charge accumulated in the R light receiving unit 404 is transferred through the G light receiving unit 403, the color mixture occurs. The electric charge that is generated is the shaded portion 40.
It is considered to be a part of the charge amount shown in 6. The information in the shaded area 406 corresponds to the shaded area 408 in consideration of the electric charge generated in the R light receiving portion 404 in time, and therefore, when the sub-scanning direction 401 and the transfer direction 402 are opposite, the light receiving portion R40.
The information mixed in 4 is the image information at the position delayed by L1 in time, and the G light receiving unit 402 corresponding to the shaded portion 408.
It can be seen that this is a part of the charge amount of.

Further, as shown in FIG. 3, the case where the sub-scanning direction 501 and the transfer direction 502 are the same direction in this embodiment will be considered similarly. If the charge generated in the R light receiving unit 507 is accumulated and transferred during the shaded portion 507, the mixed color charge is the charge in the shaded portion 506 generated in the B light receiving unit 505. The information in the shaded area 506 corresponds to the shaded area 508 in consideration of the electric charge generated in the R light receiving portion 504 with time.
It can be seen that the information mixed in 4 is image information at a position advanced by L2 in time. What is important here is how far the image information affected by the color mixture is from the image information read by its own light receiving unit. If the amount of change in the contrast of the image information is large and the cycle is short, such as a thin line pattern,
In particular, it is clear that the effect of the color mixture of electric charges is smaller as the image information affected by the color mixture is closer to the image information read by the light receiving unit of the user. Now, assuming that the size of one side of the light receiving unit is A and the pitch of the light receiving unit in the sub-scanning direction is 2A, the position of the image information for color mixing due to the difference between the transfer direction and the sub-scanning direction is L1 = 2. .5A L2 = 1.5A.

As is clear from the above values, it is very effective that the direction in which the image information is sub-scanned on the image sensor coincides with the direction in which charges are transferred via different colors. (Embodiment 2) As shown in FIG. 4, CCs are provided between the light receiving portions of the respective colors.
A light receiving section (pixel) of a different color for transferring (shifting) charges received and accumulated without arranging the D transfer section to the CCD transfer section
In the case where the CCD transfer unit is arranged in one of the sub-scanning directions with respect to the light receiving unit, the image information is scanned on the linear image sensor in the charge transfer direction. By setting so as to match the directions, it is possible to reduce the influence of charge color mixing as in the first embodiment.

As described above, according to the above-mentioned embodiment, when the charges received and accumulated in the light receiving portion are transferred via the light receiving portions of different colors, the direction of transferring the charges in the sub-scanning direction By configuring so that the image information on the linear image sensor matches the scanning direction of the image information, the image information affected by the color mixture becomes information that is close in position to the image information read by its own light receiving section, and It is possible to reduce the influence of.

The present invention can be applied to a modified or modified version of the above embodiment without departing from the spirit of the present invention.

[0020]

As described above, according to the image reading apparatus, the image reading method and the image pickup apparatus of the present invention,
When the charges received and accumulated by the light receiving unit are transferred via the light receiving units of different colors, by matching the direction of transferring the charges with the sub-scanning direction in which the image information is scanned on the linear image sensor, Compared with the case where charges are transferred in the direction opposite to the sub-scanning direction, the positions of image information for color mixing are closer to each other, and the influence of color mixing on the deterioration of image quality can be reduced.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a linear image sensor according to a first embodiment of the present invention.

FIG. 2 is a diagram showing charge accumulation and color mixing when the scanning direction and the transfer direction are opposite.

FIG. 3 is a diagram showing charge accumulation and color mixing when the scanning direction is the same as the transfer direction.

FIG. 4 is a configuration diagram of an image sensor in which a CCD transfer unit is arranged on one side in a sub scanning direction with respect to a light receiving unit.

FIG. 5 is a diagram illustrating a color image reading device using a linear image sensor.

FIG. 6 is a configuration diagram of a conventional linear image sensor.

[Explanation of symbols]

101 G light receiving unit 102 R light receiving unit 103 B light receiving unit 104, 105, 106, 107, 108, 109 C
CD transfer unit 110, 111, 112, 113, 114, 115 Amplifier A Side of pixel 201 CCD 202 Lens 203 Broken line portion 205 Second mirror 206 Third mirror 207 Broken line portion 208 First mirror 209 Reflective shade 210 Light source 211 Original platen glass 212 original document 301 R light receiving section 302 G light receiving section 303 B light receiving section 304, 305, 306, 307, 308, 309 C
CD transfer unit 310, 312, 313, 314, 315, 316 Amplifier 401, 501 Sub-scanning direction 402, 502 Transfer direction 403, 503 G light receiving unit 404, 504 R light receiving unit 405, 505 B light receiving unit 406, 506 Charges to be mixed 407, 507 Charges to be accumulated 408, 508 Positions of charges to be mixed 409, 509 Leading edge of image information

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location G06F 15/64 325 F

Claims (5)

[Claims] 1. An image reading apparatus for reading a color image by scanning a document in a main scanning direction and a sub-scanning direction while irradiating the document with light and photoelectrically converting reflected light reflected from the document using a line sensor. In order to shift the charges received and accumulated in the light receiving section of the line sensor to the charge transfer section, without the charge transfer section disposed between the plurality of line sensors corresponding to each color. , A linear image sensor configured to pass through the light receiving units of different colors, and the transfer direction of the charges accumulated in the light receiving unit is in the sub-scanning direction in which the read image is scanned on the linear image sensor. An image reading device characterized by matching. 2. The image reading apparatus according to claim 1, wherein the plurality of line sensors are three line sensors including color filters corresponding to respective colors of red, green and blue. 3. An image reading method for reading a color image by scanning a document in the main scanning direction and the sub-scanning direction while irradiating the document, and photoelectrically converting reflected light reflected from the document using a linear image sensor. When a charge transfer unit is not arranged between the light receiving units of the respective colors of the linear image sensor, and the charges received and accumulated by the light receiving unit are shifted to the charge transfer unit, the light receiving units of different colors are used. An image reading method, characterized in that the transfer direction of the charges accumulated in the light receiving unit is made to coincide with the sub-scanning direction in which the read image is scanned on the linear image sensor. 4. A first line sensor, a second line sensor, and a first line sensor, the first line sensor and the second line sensor.
And a transfer unit for reading out the charges of the second line sensor in the main scanning direction, a sub-scanning unit for relatively sub-scanning the first and second line sensors and the subject, and the first line sensor. The image pickup device is characterized in that the charge signal is transferred to the transfer means via the second line sensor, and the transfer direction and the sub-scanning direction by the sub-scanning means are the same direction. 5. The image pickup apparatus according to claim 4, wherein the sensitivity of the second line sensor is lower than the sensitivity of the first line sensor.