JP3029444B2 - Image reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a three-line type color line sensor (CC).
More specifically, the present invention relates to an image reading apparatus using D), and more specifically, controls a clock frequency and the number of driven line sensors in accordance with various reading modes to enable reading processing in accordance with image data, thereby reducing heat generation of the line sensor. The present invention relates to an image reading apparatus that suppresses image reading.

[Conventional technology]

2. Description of the Related Art Conventionally, many image forming apparatuses have been provided that optically read an image, execute various processes on the read image, and output the processed image.

In recent years, an image forming apparatus including an image reading apparatus that reads not only a monochrome image but also a color image in real time to process a full-color image, for example, a color digital copying machine has been proposed.

FIG. 4 is a schematic configuration diagram of the color digital copying machine 400. The digital copying machine 400 is roughly divided into an image reading unit 401 and an image forming unit 402.

The image reading unit 401 includes a contact glass 404 on which a document 403 is placed, a document cover 405 that presses the document 403 on the contact glass 404 to fix its position, and an optical An optical lamp 406 for performing scanning, mirrors 407, 408, 409 for reflecting and guiding light from the optical lamp 406 in a predetermined direction, and a lens 410
And three line sensors (hereinafter, referred to as CCDs) 411 for forming an image via the lens 410, and input full-color information from the CCDs 411 as red (R), green (G), and blue (B) components, respectively. And a signal processing unit 412 for executing predetermined signal processing.

Next, based on a signal input from the signal processing unit 412 of the image reading unit 401, the image forming unit 402 includes a laser driver 414 that drives a semiconductor laser 413 that outputs a laser beam.
And a mirror 416 (417 is a polygon mirror, 418 is a polygon mirror) for guiding the laser beam output from the semiconductor laser 413 to the photosensitive drum 415.
Is an fθ lens), a charging charger 419 that uniformly charges the surface of the photoconductor drum 415, and after the charging process of the surface of the photoconductor 415 is completed by the charging charger 419, the electrostatic latent image formed by the laser beam is A magenta developing device 420 that performs a developing process using magenta toner, a cyan developing device 421 that also performs a developing process using cyan toner, a yellow developing device 422 that also performs a developing process using yellow toner, and transfer of various sizes. A paper feed cassette 424 for storing paper, a paper feed roller 425 for feeding one-by-one transfer paper from the paper feed cassette 424 toward the transfer unit, and a transfer paper fed by the paper feed roller 425 to a predetermined position. A registration roller 426 for sending to the transfer section at a timing;
A transfer drum 427 that grips the transfer paper sent out by the above and performs a transfer process a plurality of times, a transport belt 428 that transports the transfer paper that has completed the transfer process, and a transfer belt 428 that is transported by the transport belt 428 Fixing device 429 for fixing images
And a discharge tray 430 from which the transfer paper is discharged after the fixing process by the fixing device 429 is completed, and the photosensitive drum 4 after the transfer is completed.
15 includes a static eliminator 431 for removing residual charges on the surface, and a cleaning device 432 for removing residual toner on the surface of the photosensitive drum 415 in the same manner.

FIG. 5 is a block diagram showing a driving system of the three-line CCD 411. The oscillator 503 outputs a predetermined frequency clock, and the output clock from the oscillator 503 is divided.
Timing generator 50 that executes each phase inversion process
2 and a CCD driver 501 that drives a three-line CCD 411 according to the output from the timing generator 502.

FIG. 6 is a block diagram showing the configuration of the signal processing unit 412. The amplifiers 601R, 601G, 601B amplify the outputs from the line sensors 411R, 411G, 411B of the CCD 411, and the amplifiers 601R, 601G, 601B. A / D converters 602R, 602G, 6 that convert amplified analog data from
02B and the output of the R system by the line sensor 411R at a distance of 2 l
Delay processing means 603R for delaying the output of the G system by the line sensor 411G by a distance l.
It is composed of a 3G and a digital processing unit 604 that inputs each output and executes a predetermined process.

 The operation of the above configuration will be described.

The position of the color document 403 placed on the contact glass 404 is fixed by the document cover 405, and in this state, the optical lamp 406 optically scans the document 403. The light reflected from the document 403 by the optical scanning is reflected by mirrors 407 and 40.
8, 409 and led to the CCD 411 via the lens 410, the CCD 411
An image is formed at. The full-color information incident on the CCD 411 is output to the signal processing unit 412 as red (R), green (G), and blue (B) components, respectively.

The CCDs 411 (each of the CCDs 411 R, 411 G, and 411 B) are input to the CCD drivers 501 R, 501 G, and 501 B after a predetermined frequency clock output from the oscillator 503 is frequency-divided by the timing generator 502 and the phase inversion process is performed. Then, they are driven by the CCD drivers 501R, 501G, and 501B.

In the signal processing 412, the line sensors 411R and 411
The outputs of G and 411B are processed independently.

The output of each line sensor 411R, 411G, 411B is amplifier 601
After being amplified by R, 601G, 601B, A / D converter 602
It is converted into a digital signal by R, 602G and 602B. After that, the R system output from the line sensor 411R is output to the delay processing means.
The delay processing of the distance 2l is performed by the line sensor 603R, the G system output by the line sensor 411G is delayed by the distance 1 by the delay processing means 603G,
The system output is output to the digital processing unit 604 as it is. The digital processing unit 604 performs a predetermined process, and thereafter outputs data of R, G, and B bits each to the outside.

The data signal output from the signal processing unit 411 is input to the laser driver 414, and the laser driver drives the semiconductor laser 413 according to the data signal. The laser beam output from the semiconductor laser 413 is a polygon
17, the photosensitive drum 41 via the fθ lens 418 and the mirror 416
Guided to 5. The surface of the photosensitive drum 415 is uniformly charged in advance by the charging charger 419, and an electrostatic latent image corresponding to image information is formed by the laser beam. First, magenta development is performed on the electrostatic latent image formed on the photosensitive drum 415 by the magenta developing device 420 corresponding to the color of the exposure filter. At the same time as this operation, the transfer paper is fed from the paper feed cassette 424 toward the transfer unit by the paper feed roller 425 and sent out to the transfer drum 427 by the registration roller 426 at a predetermined timing. The transferred image is transferred to the transfer paper by the transfer drum 427, and the transfer paper after the transfer process is held by the transfer drum 427 for the next transfer process. Second, the next electrostatic latent image formed on the photosensitive drum 415 by the same operation as described above is cyan-developed by the cyan developing device 420 corresponding to the color of the exposure filter, and
The visualized image is transferred onto the transfer paper held by 17 in a superimposed manner. Similarly, the electrostatic latent image formed next is yellow-developed by a yellow developing device 422 corresponding to the color of the exposure filter, and the visible image is further superimposedly transferred onto the transfer paper held by the transfer drum 417. The transfer paper on which the final transfer process has been completed is conveyed to the fixing device 429 by the conveyance belt 428, and after the image fixing process is performed in the fixing device 429, the transfer paper is discharged to the discharge tray 430. The surface of the photosensitive drum 415 that has completed the transfer process is cleaned by the charge remover 431 and the cleaning device 432 to prepare for the next copy process.

[Problems to be solved by the invention]

However, in the above conventional image reading apparatus,
Regardless of the color reading mode, monochrome / mono color reading mode, or character reading mode that does not require high-gradation image data, the same frequency clock output by a single oscillator is output to the CCD via the timing generator. Each is input to the CCD driver and driven by the CCD driver, so in the color reading mode,
It is difficult to increase the reading speed in a monochrome / mono color reading mode or a character reading mode in which high-gradation image data is not required, because high image reading processing corresponding to a color image is not realized. There is a problem.

In addition, in the conventional configuration, since all the CCDs are always operated in all the modes, there is a problem that the CCDs, especially the CCD drivers are heated, which has an adverse effect on the device itself.

The present invention has been made in view of the above, and in the color reading mode, while suppressing the heating of the CCD driver to realize high-quality image reading processing, the monochrome / monocolor reading mode or high-gradation image data In an unnecessary character reading mode, an object is to increase a reading speed by suppressing heating of a CCD driver.

[Means for solving the problem]

In order to achieve the above object, the present invention provides an image reading apparatus including each of R, G, and B line sensors, wherein an oscillator means for driving the line sensors at a predetermined frequency;
Switching means for switching the output from the oscillator means to each of the line sensors; and controlling the switching means so that one or two colors can be read in a monochrome / monochrome color reading mode or a character reading mode in which high-gradation image data is unnecessary. It is an object of the present invention to provide an image reading apparatus provided with control means for driving line sensors while driving all line sensors in a color reading mode.

Further, in the image reading apparatus provided with each of the R, G, and B line sensors, an oscillator means for driving the line sensor at a low frequency, an oscillator means for driving the line sensor at a high frequency, and the two oscillator means Switching means for switching the output of each of the line sensors from the oscillator means.
And the first and second switching means are controlled to drive the slow-frequency oscillator means and all-color line sensors in the color reading mode, while the monochrome / monochrome color reading mode or It is an object of the present invention to provide an image reading apparatus including a control means for driving the high-frequency oscillator means and driving only one-color or two-color line sensors in a character reading mode in which high-gradation image data is unnecessary.

[Action]

The image reading apparatus according to the present invention drives an oscillator having a low frequency in the color reading mode, and uses an oscillator having a high frequency in the monochrome / monochrome color reading mode or the character reading mode in which high-gradation image data is unnecessary. Only one or two line sensors are driven. That is, an oscillator having a different frequency is selected according to the type of the document to be read, in other words, depending on the difference in the reading mode, and / or the number of CCDs to be used is switched.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1A shows a first embodiment of an image reading apparatus according to the present invention, and corresponds to a CCD 100 composed of three CCDs 100R, 100G, and 100B, and R, G, and B for driving the CCD 100. CCD driver 1 with drivers 101R, 101G, 101B
01, an oscillator 102 that outputs a slow frequency clock (for example, 1 mega to 5 mega), an oscillator 103 that outputs a fast frequency clock (for example, 10 mega to 20 mega), and the oscillator 102 or the oscillator 103 is selectively switched. The electronic switch 104, the oscillator 102 and the oscillator
And a timing generator 105 for generating a timing signal necessary for driving the CCD from the output from 103.

Further, the CPU 106 includes a CPU 106 for controlling a selective switching process of the electronic switch 104, and an operation unit 107 for designating various reading modes and inputting the designation signals to the CPU 106.

The operation of the above configuration will be described with reference to the flowchart of FIG. 1B.

When the operator designates and inputs one of a color reading mode, a black-and-white / monochrome color reading mode, and a character reading mode that does not require high-gradation image data from the operation unit 107 (step S110), an information signal indicating the mode designation Is CPU1
06, and then the CPU 106 determines whether or not the input designation mode is the color reading mode (step S11).
1). If it is determined that the mode is the color reading mode, a control signal is output to the electronic switch 104 and the oscillator 102 is switched to the CC mode.
Connect to D100 (step S112).

As a result, since the color original can be read by the CCD 100 with a slow frequency clock, high quality of the read image can be ensured and the heat generation of the CCD driver 101 can be suppressed.

On the other hand, if it is determined in step S111 that the mode is not the color reading mode, the control signal is transmitted to the electronic switch.
The signal is output to 104 and the oscillator 103 is connected to the CCD 100 (step S113).

As a result, since the CCD 100 reads a monochrome / monochrome color original or a character original that does not require high-gradation image data with a high frequency clock, the reading speed can be increased.

FIG. 2A shows a second embodiment of the image reading apparatus according to the present invention, which corresponds to a CCD 200 composed of three CCDs 200R, 200G, and 200B, and R, G, and B for driving the CCD 200. CCD driver 2 with drivers 201R, 201G, 201B
01 and an oscillator 202 that outputs a predetermined frequency clock
And a timing generator 205 for generating a timing signal necessary for CCD driving from an output from the oscillator 202.
And a switch for switching an output from the timing generator 205 to each of the drivers 201R, 201G, and 201B.
204.

When the switch 204 is in the OFF state, it is connected to the terminal a. As a result, all the drivers 201R, 201G, 201B
A clock is output for. Conversely, in the ON state, it is connected to the terminal b, and as a result, a clock is output only to the driver 201G. In other words, when the switch 204 is in the ON state, only the driven driver 201G is driven, and only the CCD 200G connected thereto is driven.

Further, similarly to the first embodiment, there are provided a CPU 206 for controlling the selective switching process of the switch 204, and an operation unit 207 for designating various reading modes and inputting the designation signals to the CPU 206.

The operation of the above configuration will be described with reference to the flowchart of FIG. 2B.

When the operator designates and inputs one of the color reading mode, the black-and-white / monochrome color reading mode, and the character reading mode that does not require high-gradation image data from the operation unit 107 (step S210), an information signal for the mode designation Is CPU1
06, and then the CPU 106 determines whether or not the input designation mode is the color reading mode (step S21).
1). If it is determined that the mode is the color reading mode, the control signal is not output to the switch 204, the switch 204 is kept OFF (step S212), and remains connected to the terminal a. As a result, a clock is output to all the drivers 201R, 201G, and 201B, and all the CCDs 200 are driven.
Conversely, if it is determined in step S211 that the current mode is not the color reading mode, a control signal is output to the switch 204 to turn on the switch 204 (step S21).
3). In the ON state, the switch 204 is connected to the terminal b, and as a result, the clock is output only to the driver 201G. Therefore, only the driver 201G is driven, and only the CCD 200G connected thereto is driven.

As described above, when the switch 204 is in the ON state, unnecessary heat generation of the CCD driver can be controlled because the number of CCDs being driven is small.

FIG. 3A shows a third embodiment of the image reading apparatus according to the present invention, which has a configuration in which the first embodiment and the second embodiment are combined.

CCD30 composed of three CCD300R, 300G, 300B
0, a CCD driver 301 including drivers R, G, and B corresponding to the above R, G, and B for driving the CCD 300, an oscillator 302 that outputs a slow frequency clock, and an oscillator 303 that outputs a fast frequency clock. An electronic switch 304 for selectively switching the two oscillators,
A timing generator 305 for generating a timing signal required for CCD driving from an output from the electronic switch 304b;
And a switch for switching an output from the timing generator 305 to each of the drivers 301R, 301G, and 301B.
304a.

In addition, the CPU 306 and the operation unit 307 have the same configuration as in the above embodiment.

The operation of the above configuration will be described with reference to the flowchart of FIG. 3B.

When the operator designates and inputs one of various modes from the operation unit 307 (step S310), an information signal for specifying the mode is input to the CPU 306, and the input mode is the color reading mode. It is determined whether or not this is the case (step S311). If it is determined that the mode is the color reading mode, the control signal is output to the electronic switch 304b to connect the oscillator 302 to the CCD 300 (step S312). No control signal is output to the switch 304a,
Maintain the OFF state (step S312), and remain connected to the terminal a. Conversely, in step S311 above,
If it is determined that the mode is not the color reading mode, a control signal is output to the electronic switch 304b and the oscillator 303 is set to the CCD30.
0 (step S314) and switch 304a is turned on
The state is set (step S315).

Regarding the effects of the above operation, the first
And the same thing as the second embodiment is obtained.

In the second and third embodiments, only one CCD is driven when the switch 204 and the switch 304a are in the ON state. However, the switch is configured so that two CCDs are driven. Can also be used.

〔The invention's effect〕

According to the image reading device of the present invention as described above,
In the color reading mode, the oscillator with the low frequency is driven. In the monochrome / monochrome color reading mode or the character reading mode in which the high gradation image data is unnecessary, the oscillator with the high frequency is used, and only one or two line sensors are used. To drive, in the color reading mode,
In addition to realizing high-quality reading processing by suppressing the heating of the CCD driver, the reading speed is increased by suppressing the heating of the CCD driver in the black-and-white / monocolor reading mode or the character reading mode that does not require high-gradation image data. be able to.

[Brief description of the drawings]

1A is a block diagram showing a first embodiment of the image reading apparatus of the present invention, FIG. 1B is a flowchart showing the operation of the apparatus shown in FIG. 1A, and FIG. 2A is an image of the present invention. FIG. 2 is a block diagram showing a second embodiment of the reader, and FIG.
3A is a block diagram showing a third embodiment of the image reading apparatus of the present invention, and FIG. 3B is a flowchart showing the operation of the apparatus shown in FIG. 3A. FIG. 4 is an explanatory view showing the structure of a general color digital copying machine equipped with an image reading apparatus, FIG. 5 is a block diagram showing the configuration of a CCD drive system in a conventional image reading apparatus, and FIG. 1 is a block diagram illustrating a schematic configuration of a typical image reading apparatus. Description of reference numerals 100, 200, 300 CCD 101, 201, 301 CCD driver 102, 103, 202, 302, 303 Oscillator 104, 304b Electronic switch 105, 205, 305 Timing generator 106, 206, 306 CPU 107, 207, 307 Operation unit 204, 304a Switch

Claims (2)

(57) [Claims] 1. An image reading apparatus having R, G, and B line sensors, comprising: an oscillator for driving the line sensor at a predetermined frequency; and a switch for switching an output from the oscillator to the line sensor. Means for controlling the switching means to drive a one-color or two-color line sensor in a black-and-white / monochrome color reading mode or a character reading mode in which high-gradation image data is not required. An image reading device, comprising: control means for driving a sensor. 2. An image reading apparatus comprising R, G, and B line sensors, wherein: an oscillator means for driving the line sensor at a low frequency; an oscillator means for driving the line sensor at a high frequency; A first switching means for switching between the two oscillator means, a second switching means for switching an output from the oscillator means to each of the line sensors, and controlling the first and second switching means so as to be in a color reading mode. While driving the slow-frequency oscillator means and driving all-color line sensors, the fast-frequency oscillator means is driven in black-and-white / monochrome color reading mode or in a character reading mode in which high-gradation image data is unnecessary. Control means for driving only the color sensor of two colors or two colors. Image reading apparatus for.