JPH09270893A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an output signal noise from a CCD of a scanner section of a copying machine by providing a drive means, driving an image pickup element in the main scanning direction and the sub scanning direction at a prescribed speed, an integration means integrating an output signal of the image pickup element for each picture element, and a control means controlling each means so as to reduce noise. SOLUTION: An integration means is made up of an adder 3, a storage means 4 and a register 5. An address counter 6, being a control means reads a signal corresponding to a picture element processing a signal at present from a storage means 4 based on a signal from a drive section 7 and a signal, is fed to the adder 3 via the register 5. In the case that a CCD 1 is driven at a multiple of B of a conventional read speed in the main scanning direction and at a 1/B of the conventional read speed in the subscanning direction, one picture element in the case of reading the original at a conventional speed is to be read B number of times. The read data of B number of times are added by the adder 3, to emphasize substantial image information and to reduce aperiodic signals such as random noise.

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 for reading an image with an image pickup device such as a CCD.

[0002]

2. Description of the Related Art Conventionally, in an image reading device such as a copying machine using a CCD, image data output from the CCD is A / D converted and image processing is performed, and the image data is processed based on the image processed image data. To output the image.

[0003]

For example, in the CCD of the scanner section of a copying machine, the influence of peripheral circuits, power supplies, etc.
Random noise is added to the analog output voltage of the CCD. The analog output voltage containing the random noise is A / D-converted, so that an image is output to a place where nothing is present on the document, which causes a problem of image quality deterioration.

The present invention has been made to solve the above problems, and an object thereof is to obtain an image reading apparatus capable of reducing the noise of the output signal from the CCD.

[0005]

In the present invention, a driving means for driving the image sensor at a predetermined speed in the main scanning direction and the sub-scanning direction, and an integrating means for integrating the output signal of the image sensor for each pixel. Driving the image pickup device in the main scanning direction at a speed faster than a predetermined speed and driving it in the sub-scanning direction at a speed slower than the predetermined speed by the driving means, and further integrating the output signal for each pixel by the integrating means. Therefore, a control unit for controlling so as to reduce noise is provided.

[0006]

According to the present invention, the data having periodicity can be emphasized by the integrating means, the data having no periodicity (random noise) can be reduced, and the S / N ratio of the image can be improved. it can.

[0007]

FIG. 1 shows a first embodiment of the present invention. In the figure, 1 is a CCD, 2 is an A / D converter for converting the output signal of the CCD 1 into a digital signal, and 3 is an A
The adder 4 for adding the output of the / D converter 2 and the output of the register 5 to be described later, the storage means 4 for storing the output of the adder 3, and the reference numeral 5 for temporarily holding the output of the storage means 4, and then the adder 3
A register for sending to the memory, 6 is an address counter for designating addresses for writing and reading in the storage means 4, and 7 is a CCD
1, a driving unit that drives the A / D converter 2 and the address counter 7. Incidentally, the adder 3, the storage means 4, and the register 5 constitute an integration means.

Next, the operation will be described. The driving unit 7 drives the CCD 1 in the main scanning direction at a normal B-fold reading speed, and drives it in the sub-scanning direction at 1 / B times. The analog output signal of the CCD 1 is converted into a digital output signal by the A / D converter 2. Address counter 6
Reads out a signal corresponding to the pixel currently processing the signal from the storage means 4 on the basis of the signal from the drive section 7, and this signal is sent to the adder 3 via the register 5. The adder 3 adds the output signal of the CCD 1 and the signal of the storage means 4 corresponding to the signal, and the addition result is newly stored in the corresponding location of the storage means 4.

When the CCD 1 is driven at B times the normal reading speed in the main scanning direction and 1 / B times in the sub scanning direction, one pixel when the original is read at the normal speed is read B times. By adding the read data for B times by the adder 3, as shown in FIG. 2, a periodic element in the signal, that is, original image information is emphasized, and a non-periodic signal, for example, random noise is added. It can be reduced.

FIG. 3 is a flowchart showing the above operation. In the figure, in step S1, the number of pixels α and the number of readings n
The ranges are set to 1 ≦ α ≦ A and 1 ≦ n ≦ B, respectively.
Next, in step S2, the αth pixel of CCD 1 is read out, and in step S3, A / D conversion is performed. On the other hand, step S
In step 4, the signal of the α-th pixel is read from the storage means 4 and transferred to the register 5 in step S5. Then, in step S6, the adder 3 adds the signals obtained in steps S3 and S5, and the addition result is stored in the storage means 4 in step S7.

The above steps S2 to S7 are repeated while increasing .alpha. By 1 in step S9 until .alpha. = A in step S8. Then, when α = A, the process of steps S2 to S9 is performed in step S10 by n =
Until n is reached, the process is repeated while incrementing n by 1 in step S11. When n = B, the storage means 4
The signals of all the pixels stored in are output.

FIG. 4 shows a second embodiment of the present invention.
In the figure, 8 ₁ to 8 _B are B storage means, 9 is an A / D
A switch 10 for distributing the output of the converter 2 to the storage means 8 ₁ to 8 _B is an adder for adding the respective outputs of the storage means 8 ₁ to 8 _B. Incidentally, the switch 9, the storage means 8 ₁ to 8 _B , and the adder 10 constitute an integration means. Also, the storage means 8
₁ to 8 _B are controlled by the address counter 6. Other configurations are the same as those in FIG.

Next, the operation will be described. The driving unit 7 drives the CCD 1 in the main scanning direction at a reading speed of B times the normal speed, and at the same time drives in the sub scanning direction at 1 / B times,
The analog output signal of D1 is converted into a digital output signal by the A / D converter 2. This output signal is stored in one of the storage means 8 ₁ to 8 _B determined via the switch 9 which is switched by the signal of the drive unit 7. Adder 10
Then, the signals of the same positions of 8 ₁ to 8 _B of each storage means designated by the address counter 6 are added by the signal of the drive section 7 and output.

In this way, the signals for B times are stored in the storage means 8 ₁ ...
Since the signals are added and output by the adder 10 at the time of storage in 8 _B , this output signal is a signal obtained by scanning B times at the same position as shown in FIG. As shown in FIG. 2, a periodic signal is emphasized and an aperiodic signal component such as random noise is reduced.

FIG. 6 is a flow chart showing the above operation. In the figure, after setting n = 1 in step S21,
In step S22, the nth scan of the CCD 1 is performed,
The data is stored in the storage means 8n in step S23. The processes of steps S22 and S23 are performed in step S2.
It is performed while increasing n by 1 in step S25 until n = B in 4. Then, when n = B, the data in the respective storage means 8 ₁ to 8 _B are added and output in step S27.

[0016]

As described above, according to the present invention, it is possible to reduce the random noise component of the output signal of the image pickup device, thereby improving the image quality of the output image and the reproducibility of the output image.

[Brief description of drawings]

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

FIG. 2 is a waveform diagram for explaining the effect of the present invention.

FIG. 3 is a flowchart showing an operation of the first embodiment.

FIG. 4 is a block diagram showing a second embodiment of the present invention.

FIG. 5 is a configuration diagram for explaining the operation of the second embodiment.

FIG. 6 is a flowchart showing an operation of the second embodiment.

[Explanation of symbols]

1 CCD 3 adder 4 storage means 5 register 7 drive section 8 ₁ to 8 _B storage means 9 switch 10 adder

Front page continuation (72) Inventor Chiichirou Ota 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Masafumi Kamei 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. Within

Claims (4)

[Claims] 1. A driving means for driving the image sensor at a predetermined speed in the main scanning direction and the sub-scanning direction, an integrating means for integrating an output signal of the image sensor for each pixel, and the driving means for driving the image sensor. The main scanning direction is driven at a speed faster than a predetermined speed, the sub scanning direction is driven at a speed slower than a predetermined speed, and the output signal is integrated pixel by pixel by the integrating means to reduce noise. An image reading apparatus comprising: 2. The integrating means comprises a storage means, and an adding means for adding the output signal of the image pickup device and the output signal of the storage means for each pixel and inputting the added output signal to the storage means. The image reading apparatus according to claim 1, wherein the image reading apparatus is formed. 3. The integrating means comprises a plurality of storage means for storing an output signal obtained in a main scan of the image sensor for each scan, a distributing means for distributing the output signal to the plurality of storage means, and The image reading apparatus according to claim 1, further comprising: an addition unit that adds the output signals of the plurality of storage units for each pixel. 4. The image reading apparatus according to claim 1, wherein the ratio of the reading speed in the main scanning direction and the reading speed in the sub scanning direction has an inversely proportional relationship.