JP2005094660A - Image scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image scanner capable of performing color image processing by a CCD which outputs three channels with no memory capacity and a image processing circuit required for the three channels, at a low cost of a image processing part. <P>SOLUTION: The image scanner uses a line sensor which outputs simultaneously a plurality of colors of image signals corresponding to the same position in a read original in a single integration time. It comprises a selecting means for selecting only a single image signal from among a plurality of colors of image signals outputted simultaneously in a single integration time, and an image processing means which performs an image process with the image signal selected by the selecting means. The selecting means sequentially switches the image signals so that the image processing means sequentially performs image processes about all of the plurality of colors of image signals. The image data for a single line is processed a plurality of integration times. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to an image reading apparatus that reads an image of a document and outputs the read image data.

  Generally, in an image reading apparatus that reads an image of a document and outputs the read image data, the document is read line by line using a line sensor in which a plurality of sensors corresponding to each pixel are arranged in a line.

  Two types of line sensors are known: a CCD sensor and a contact sensor (CIS). Since each has a characteristic, a sensor to be used is selected according to the character of the image reading apparatus.

  When a color original is read using a line sensor, a color CCD sensor usually has a sensor corresponding to each color of RGB, one line each, that is, three lines, and a white light source. With one accumulation time, it is possible to simultaneously obtain output signals for one line for each of the three colors RGB.

  In CIS, normally, only one line is used for the sensor, and the color of the light source is switched in accordance with each of RGB, and one line is output for one color of RGB within one accumulation time. Get a signal. Therefore, when CIS is used, RGB data for one line is prepared after three accumulation times have elapsed.

  FIG. 4 is a diagram illustrating an example of an image signal output for each line when a CCD is used, and an example of an image signal output for each line when a CIS is used.

  In FIG. 4, one interval of the signal TG is the accumulation time, and Vout is the output image signal.

  The image processing method in the image processing apparatus differs depending on the sensor used. That is, the color CCD sensor outputs RGB image signals independently, and simultaneously outputs RGB image signals at the same position in the read image document in one accumulation time cycle. Therefore, the subsequent image signal processing circuit also requires a three-channel image processing circuit corresponding to each color so that three image signals can be processed simultaneously within one accumulation time.

  On the other hand, in CIS, the output image signal is only one channel, and only one color image signal is output within one accumulation time. Therefore, it is sufficient to provide only one channel for the subsequent image signal processing circuit.

FIG. 5 is a diagram showing an example of a conventional image processing circuit, and FIG. 5 (1) shows an example of a conventional image processing circuit when a CCD is used (for example, see Patent Document 1). (2) is a figure which shows the example (for example, refer patent document 2) of the conventional image processing circuit at the time of using CIS.
JP-A-5-103185 JP 2001-320559 A

  When a CCD is used as an image reading sensor, a circuit for simultaneously processing signals of three channels as described above is required, so that there is a problem that the system becomes complicated and the cost of the apparatus increases.

  Also, since the hardware and software are completely different between the image reading device using CIS as the image reading sensor and the image reading device using CCD as the image reading sensor, CIS was used as the image reading sensor. There is a problem that it is not easy to change the image reading device to an image reading device using a CCD as an image reading sensor.

  The present invention provides an image reading apparatus capable of executing color image processing of a CCD that outputs three channels without a memory capacity for three channels and an image processing circuit, and having a low cost for the image processing portion. It is for the purpose.

Another object of the present invention is to provide an image reading apparatus that uses a CIS as an image reading sensor in an image reading apparatus that uses a CCD as an image reading sensor. Is.

According to the present invention, in an image reading apparatus using a line sensor that simultaneously outputs image signals of a plurality of colors corresponding to the same position on a read document within one accumulation time, the image is simultaneously output within one accumulation time. A selection unit that selects only one image signal from among the image signals of a plurality of colors; and an image processing unit that performs image processing on the image signal selected by the selection unit. The selection unit sequentially selects the image signals. By switching, the image processing means sequentially performs image processing on all the image signals of the plurality of colors and processes image data for one line in a plurality of accumulation times.

  According to the present invention, when the CCD outputs signals for three channels, color image processing can be executed without the memory capacity and image processing circuit for three channels, and the cost of the image processing portion can be increased. There is an effect that can be reduced.

Further, according to the present invention, when an image reading apparatus using a CCD as an image reading sensor is changed to use a CIS as an image reading sensor, there is an effect that the change is small.

  The best mode for carrying out the invention is the following examples.

  FIG. 1 is a block diagram showing an image reading apparatus IR1 that is Embodiment 1 of the present invention.

  The image reading device IR1 includes a CCD line sensor 1, a clock generator 2, a control unit 3, a switch 4, a gain control circuit, an offset adjustment circuit 5, an AD converter 6, a shading correction circuit 7, a memory 8a, 8 b, LUT (Look Up Table) 9, image processing circuit 10, and output control unit 11.

  The CCD line sensor 1 outputs an image signal in response to a drive signal from the clock generator 2. The switch 4 receives the RGB image signal from the CCD 1, and selects and outputs one of the RGB image signals based on the signal from the control unit 3.

  The gain control circuit and the offset adjustment circuit 5 include a gain control circuit that amplifies the level of the image signal and an offset adjustment circuit. The AD converter 6 converts an analog image signal into digital image data. The image signal is adjusted to match the input range of the AD converter 6 by the gain control circuit and the offset adjustment circuit 5 in the previous stage. The shading correction circuit 7 performs a shading correction calculation for each pixel. A LUT (Look Up Table) 9 performs gamma conversion. Image data subjected to various types of image processing by the image processing circuit 10 is output by the output control unit 11 and output to an output device such as a printer or a personal computer.

  The memories 8a and 8b are memories that hold data necessary for shading correction and various image processing.

  Next, the operation of the above embodiment will be described.

  FIG. 2 is a diagram for explaining an image signal switching operation in the above embodiment.

  The signal TG is a pulse signal generated by the clock generator 2 and input to the CCD 1, and the interval of the signal TG is an accumulation time of one line of image signals output from the CCD 1. Further, the CCD 1 sequentially outputs a signal of one line from the top pixel by the signal TG. The image signal output Vin from the CCD 1 is input to the switch 4 simultaneously with RGB. The signal s1 is a selection signal that is switched simultaneously with the signal TG. When the signal s1 shown in FIG. 2 is Rsel, the switch 4 outputs only the R signal among the input signals.

  In the case of Gsel and Bsel, similarly to the above, only the G signal and only the B signal are output as the output signal Vout, respectively. In the case of color reading, the signal s1 is switched in the order of Rsel → Gsel → Bsel as shown in FIG.

  The control circuit 3 receives the signal TG from the clock generator 2 and sequentially switches the signal s1 at the timing of the signal TG. The image signal output from the switch 4 is sequentially subjected to AD conversion and image processing for each RGB color by the circuit shown in FIG. Since the image-processed data is held in the memory for each line, finally, one line of image data with RGB can be obtained in three accumulation times.

  In the above embodiment, the signal s 1 is also sent to the gain control circuit and the offset adjustment circuit 5. This is effective when it is desired to change the gain or offset for each of the RGB image signals.

  The gain control circuit and the offset adjustment circuit 5 have registers storing variables of gain and offset corresponding to each of RGB, and by selecting them by the signal s1, appropriate gain and offset adjustment for each color can be performed. can get.

  Next, a case where monochrome reading is performed in the above embodiment will be described.

  As a monochrome reading method, there is a method of converting RGB three-color output data into monochrome data. However, since there is no particular problem in practical use, a method of using a result read in a single color as monochrome data is also employed.

  In the above embodiment, in the former method (method for converting RGB three-color output data to monochrome data), it takes three accumulation times to obtain monochrome one-line data. Not suitable for reading. Therefore, when speed is important, the latter method (a method of using a result read in a single color as monochrome data) is employed.

  FIG. 3 is a diagram for explaining the operation of not switching the image signal in the above embodiment.

  As shown in FIG. 3, for example, if the same color is always selected without switching the signal s1, a method of using the result read in a single color as monochrome data can be realized.

  In the example shown in FIG. 3, the G signal is selected. However, other signals may be selected, and the color to be selected can be selected according to the status of the document.

  That is, in the above-described embodiment, in an image reading apparatus using a line sensor that simultaneously outputs image signals of a plurality of colors corresponding to the same position on a read document within one accumulation time, the image reading apparatus simultaneously performs within one accumulation time. A selection unit that selects only one image signal from among the output image signals of a plurality of colors; and an image processing unit that performs image processing on the image signal selected by the selection unit. An example of an image reading apparatus in which the image processing means sequentially performs image processing on all of the plurality of color image signals and processes image data for one line in a plurality of accumulation times by sequentially switching the signals. It is.

Note that the switch 4 is an example of a selection unit that selects only one image signal from a plurality of color image signals output simultaneously within one accumulation time. The image processing circuit 10 is an example of an image processing unit that performs image processing on the image signal selected by the selection unit.

1 is a block diagram illustrating an image reading device IR1 that is Embodiment 1 of the present invention. FIG. In the said Example, it is a figure explaining the switching operation | movement of an image signal. FIG. 6 is a diagram for explaining an operation in which image signals are not switched in the embodiment. It is a figure which shows the example of the image signal output for every line when using CCD, and the example of the image signal output for every line when using CIS. FIG. 5A shows an example of a conventional image processing circuit, FIG. 5A shows an example of a conventional image processing circuit when a CCD is used, and FIG. 5B shows a conventional image processing circuit when a CIS is used. It is a figure which shows the example of this image processing circuit.

Explanation of symbols

IR1 ... image reading device,
1 ... CCD,
2 ... Clock generator,
3 ... Control part,
4 ... switch,
5 ... Gain control circuit, offset adjustment circuit,
6 ... AD converter,
7 ... Shading correction,
8a, 8b ... memory,
9: Gamma conversion LUT,
10: Image processing circuit,
11: Output control unit.

Claims (1)

In an image reading apparatus using a line sensor that simultaneously outputs image signals of a plurality of colors corresponding to the same position in a read document within one accumulation time,
Selecting means for selecting only one image signal among a plurality of color image signals output simultaneously within one accumulation time;
Image processing means for performing image processing on the image signal selected by the selection means;
And the selection means sequentially switches the image signal, so that the image processing means sequentially performs image processing on all of the plurality of color image signals, and an image for one line is obtained in a plurality of accumulation times. An image reading apparatus that processes data.

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