JP3935405B2 - Image reading apparatus and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image reading apparatus and an image forming apparatus , and more specifically, a photoelectric conversion board including a photoelectric conversion element and a control board are connected via a connection cable, and the control board is connected via the connection cable. The present invention relates to an image reading apparatus that reads document image information by a photoelectric conversion element that operates by being supplied with a drive signal, and an image forming apparatus having the image reading apparatus .
[0002]
[Prior art]
In recent years, there has been a strong demand for energy saving in image reading apparatuses, and various proposals have been made. For example, Japanese Patent Laid-Open No. 2000-184133 discloses an image reading apparatus that can prevent unnecessary radio wave radiation and reduce the cost increase for radio wave countermeasures.
Various proposals have also been made for an energy saving mode in which the power consumption of a unit that does not use the device for a certain period of time is made smaller than that in the normal mode to suppress the power consumption. In the energy saving mode, in the circuit as shown in FIG. 7, it means a mode in which all operations including the clamp signal are stopped when the operation clock is stopped, and when the operation of the machine is not requested (= standby time) Set to By using such an energy saving mode, it is possible to expect effects such as saving of electricity bill, reduction of heat generation, extension of machine life, and the like. With regard to such an energy saving mode, for example, there is a technique disclosed in JP-A-8-251316.
[0003]
[Problems to be solved by the invention]
By the way, when the energy saving mode is set, there is a problem that it takes time to return to the normal operation mode. In view of this, Japanese Patent Application Laid-Open No. 2000-69285 proposes a technique for shortening the rise time of the apparatus by shortening the substantial time until the clamp voltage is stabilized even in the situation of returning from the energy saving mode. ing.
In general, in an image reading apparatus using a linear CCD image sensor, in a situation such as returning from an energy saving mode (including power-on), a certain time is required until the clamp voltage is stabilized, and the rise time is It is a restriction of.
That is, since the line clamp circuit (not shown) included in the sample hold amplifiers 762 and 763 shown in FIG. 9 is a circuit using charging / discharging of the capacitor, the potential of the capacitor is completely set to 0V. In the discharging state, it takes time to reach a normal clamp potential.
For this reason, the drive signal that is the same as that during reading of the original image information is driven at a frequency required for the system in a mode other than the energy saving mode, and unnecessary energy is consumed. In addition, since the drive signal supplied from the control board to the photoelectric conversion element board is transmitted through the connection cable, the connection cable serves as an antenna to cause unnecessary radio wave radiation.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image reading apparatus and an image forming apparatus that do not require a rise time of the apparatus and can suppress power consumption during a standby state.
[0004]
[Means for Solving the Problems]
According to the first aspect of the present invention, the image reading means for reading a document image using a photoelectric conversion element, and the image reading means are connected to the image reading means via a connecting portion, and a drive signal is sent via the connecting portion to thereby send the image. an image reading apparatus comprising: a control means for controlling the reading means, wherein the control means includes a first drive signal frequency for sending via said connection section when reading stand, the connection during the reading operation of the original image information The frequency spread which cannot be used during the reading operation of the original image information when the first driving signal frequency is sent by switching the second driving signal frequency sent via the unit. The above-mentioned object is achieved by changing to the coefficient .
According to a second aspect of the present invention, an image reading unit that reads a document image using a photoelectric conversion element, and the image reading unit are connected to the image reading unit through a connection unit, and a drive signal is transmitted through the connection unit to transmit the image. In the image reading apparatus, comprising: a control unit that controls the reading unit ; and a light source that irradiates the original image when the image reading unit reads the original image. The first drive signal frequency to be switched and the second drive signal frequency to be transmitted through the connection unit during the reading operation of the document image information are switched and transmitted, and the first drive is performed only when the light source is turned off. The object is achieved by switching to the signal frequency for transmission .
[0005]
In the invention described in claim 3, wherein the image reading apparatus of claim 1 or claim 2, wherein, when the image reading means reads a plurality of original pages, the control means also in between pages the first time reading stand The drive signal frequency is switched to be sent out.
In the invention of claim 4, claim 1, in the image reading apparatus according to claim 2 or claim 3, further comprising a cooling fan for cooling the image reading means, said control means said first drive signal frequency This cooling fan is not driven when it is switched to and sent out.
[0006]
A fifth aspect of the invention achieves the object by including the image reading device according to the first, second, third, or fourth aspect.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to FIGS.
FIG. 1 is a diagram showing a configuration of a digital copying machine according to an embodiment of the present invention.
The mechanism of this apparatus is roughly constituted by a copying machine main body 1, an automatic document feeder (ADF) 100, an in-body discharge tray 200, and a paper feed unit (bank) 300.
The automatic document feeder 100 feeds the documents stacked on the document feeding table 101 one by one onto the contact glass 10 on the copying machine main body 1 side, and discharges them onto the discharge tray 105 after reading the image. It has become.
[0008]
The document on the document feeder 101 is aligned in the width direction by a side fence (not shown), separated from the uppermost document by the feed roller 102, and fed onto the contact glass 10 by the transport belt 103. Paper.
The feeding unit 107 is provided with a document width detection sensor 108 and a document length detection sensor 109. The size of the document fed from the automatic document feeder 100 is detected by both the sensors.
The original on the contact glass 10 is discharged onto the paper discharge tray 105 by the conveyance belt 103 and the paper discharge roller 104 after reading is completed.
When reading a double-sided document, the document on the document feeder 101 is separated from the top document by the feed roller 102 and fed, and passes through the contact glass 10 by the conveyor belt 103. It is reversed by the reversing claw 106, fed again onto the contact glass 10, and the back surface is read.
Next, the original on the contact glass 10 is transported by the transport belt 103 after being read from the back surface, reversed by the reversing claw 106, fed again onto the contact glass 10, and the front surface is read. Then, the original after the front surface reading is discharged onto the discharge tray 105 by the conveyance belt 103 and the discharge roller 104.
[0009]
FIG. 2 is a view showing the appearance of the automatic document feeder 100. As shown in this figure, the automatic document feeder 100 is opened and closed around hinges 81 and 82. A claw 83 is provided on the upper surface of the copier body 1 in the vicinity of the hinge 81. A hole 84 is provided in the lower surface of the automatic document feeder 100 at a position where the claw 83 faces when the feeder 100 is closed. Further, when the automatic document feeder 100 is closed, the claw 83 is inserted through the hole 84.
Inside the automatic document feeder 100 adjacent to the hole 84, a lift-up detection sensor 85 and a document detection timing sensor 86 for detecting the presence or absence of the claw 83 inserted through the hole 84 are provided.
[0010]
The lift-up detection sensor 85 detects the claw 83 when the automatic document feeder 100 is completely closed (lifted down) and turns on, and turns off when the automatic document feeder 100 is opened (lifted up). It becomes a state. The completely closed state refers to a state in which a part of the lower surface side of the automatic document feeder 100 is in contact with the upper surface of the copying machine main body 1.
On the other hand, the document detection timing sensor 86 is provided for controlling the timing of detecting the document size on the contact glass 10 based on the detection result of the document size detection sensor described later, and the automatic document feeder 100 is opened. When the angle is within a predetermined angle, the claw 83 is detected and turned on.
This predetermined angle is a slight angle, and when the operator manually opens the automatic document feeder 100, both the lift-up detection sensor 85 and the document detection timing sensor 86 are turned off. 87 and 88 are end face scales.
[0011]
FIG. 3 is a view showing a contact glass, and FIG. 4 is a view showing a document size detection sensor. As shown in FIG. 3, document size detection sensors 91 to 93 are provided below the contact glass 10. As shown in FIG. 4, each of the document size detection sensors 91 to 93 irradiates the light emitted from one light emitting diode 91a by dispersing it into three beams, and irradiates the reflected light to three light beams inside the optical system. It is a reflective sensor that receives light by the light receiving element 91b, and detects the presence or absence of a document by receiving only reflected light from the document surface through the contact glass 10 from the inside of the optical system.
The document size detection sensors 91 to 93 are always operating, and each light receiving element is turned on when a document on the contact glass 10 is detected, and is turned off when a document is not detected.
The document size detection sensors 91 to 93 are arranged according to the sizes of a plurality of types of documents placed at predetermined positions on the contact glass 10. From this, it is determined whether or not there is a document on the contact glass 10, and the size of the document on the contact glass 10 is detected.
[0012]
The copying machine main body 1 includes a scanner unit that reads a document, an image processing unit, a plotter unit, and the like. The scanner unit is provided with a contact glass 10 for placing a document and an optical scanning system. The optical scanning system includes an exposure lamp 11, a first mirror 12, a second mirror 13, a third mirror 14, and a lens 15. CCD 16 etc. are provided.
The exposure lamp 11 and the first mirror 12 are mounted on a first carriage, and the first carriage moves in the sub-scanning direction at a constant speed by a stepping motor when reading a document. The second mirror 13 and the third mirror 14 are mounted on the second carriage, and the second carriage is moved at a speed half that of the first carriage by a stepping motor when reading a document.
The original on the contact glass 10 is optically scanned by the movement of the first carriage and the second carriage, and is imaged on the light receiving surface of a CCD (photoelectric conversion element) 16 by the lens 15 and subjected to photoelectric conversion.
[0013]
The image signal obtained by the CCD 16 is A / D (analog / digital) converted by an image processing circuit, and then subjected to various image processing by an image processing unit 604 (see FIG. 6). Is copied to the recording paper.
The writing unit includes laser output units 20 and 25, an fθ lens 21, and mirrors 22, 23, 24, 26, and 27. The laser output units 20 and 25 include a laser diode (LD) that is a laser beam and a polygon (not shown). A mirror and polygon motor are provided.
The laser output units 20 and 25 emit black signal laser light modulated according to the image read by the scanner during copying, and a latent image is formed on the photoconductor 30. Around the photosensitive member 30, a black developing device 32, a red developing device 33, a transfer conveying device 54, a separator (not shown), and the like are arranged, and a toner image on the photosensitive member 30 is recorded on a sheet.
[0014]
The paper is selected from the duplex unit 40 and the first tray 50 in the copying machine main body 1, and one of the second tray 310, the third tray 320, and the fourth tray 330 in the sheet feeding unit 300. Paper is fed by a pair of rollers of the reversible roller 42 and the contact / separation roller 43, the first paper feeding device 51, the second paper feeding device 311, the third paper feeding device 321 and the fourth paper feeding device 331, respectively.
The paper fed from each tray abuts against the registration roller 53 after a predetermined time after the leading edge of the paper is detected by the registration sensor 52 and stops temporarily, and the registration roller is synchronized with the sub-scan valid period signal (FGATE). 53, and the toner image on the photosensitive member 30 is transferred by the transfer conveying device 54.
Next, after the sheet is separated from the photoconductor 30, the toner image is fixed by the fixing device 55. The sheet after fixing is discharged to the in-body discharge tray 200 by the switching claw 57 and the paper feed roller 56 during single-sided printing and after double-sided printing.
On the other hand, the paper after the back side printing at the time of double-sided printing is guided to the double-sided conveyance path 41 by the switching claw 57, reversed by the reversible roller 42 and the contact / separation roller 43, and conveyed into the double-sided unit 40. The paper in the duplex unit 40 is sent to the vertical conveyance unit to form an image on the surface.
[0015]
FIG. 5 is a block diagram showing a control system of the digital copying machine. In this figure, an operation unit controller 500 performs control of liquid crystal display and various LEDs on the operation unit, and control of various key inputs, and a system controller 501 performs sheet feeding, conveyance, fixing, duplex printing, process control, and the like.
The image processing controller 502 performs image control and scanner reading control, and the ADF controller 503 controls the automatic document feeder 100. The paper feed tray controller 504 controls the paper feed tray, the fax controller 505 performs fax transmission / reception management and file management, and the printer controller 506 performs printer data reception management and file management.
[0016]
FIG. 6 is a block diagram showing an image processing circuit of the digital copying machine.
The document 600 on the contact glass 10 is illuminated by the exposure lamp 11 and the reflected light is read by the CCD 16. Next, the analog image signal separated into R (red), G (green), and B (blue) by the CCD 16 is amplified by the signal processing circuit 601 to correct the light amount, and converted into a digital image signal by the AD converter 602. Then, the shading correction is performed by the shading correction circuit 603 and sent to the image processing unit 604.
The image processing unit 604 performs image quality processing such as MTF correction, γ correction, black image generation, binary processing, and multi-value processing, and outputs black data to the selector 605. The selector 605 switches the destination of the image signal to the scaling unit 606 or the image memory controller 608. The image signal that has passed through the scaling unit 606 is enlarged / reduced in accordance with the scaling factor and sent to the writing unit 607.
[0017]
Between the image memory controller 608 and the selector 605, image signals can be input and output bidirectionally. In addition, the CPU 609 performs settings for the image memory controller 608 and the like, and controls the reading unit and the writing unit, a ROM (read only memory) 610 for storing the program and data, and a RAM (random access memory). 611 is provided. Further, the CPU 609 can write and read data in the image memory 612 via the image memory controller 608.
The image sent to the image memory controller 608 is sent to the image memory 612 after the image data is compressed by the image compression device in the image memory controller 608. By performing image compression, a limited image memory can be used effectively. In addition, since a large amount of original image data can be stored at a time, the stored original image data can be output in page order. In this case, when the image is output, the data in the image memory 612 is output while being sequentially expanded by the expansion device in the memory controller 608.
[0018]
The document image image data stored in this way is output in page order, the document image is rotated for each number of copies, and output to a recording sheet.
On the other hand, at the time of FAX transmission, the black data is transferred to the FAX image memory 613 by the selector 605. At the time of FAX reception, the received data is demodulated and expanded from the line, and then developed in the FAX image memory 613, and then sent to the writing unit 607 by the selector 605.
Further, when the printer data is received, it is expanded in the printer image memory 614 and then sent to the writing unit 607 by the selector 605.
[0019]
FIG. 7 is a block diagram illustrating a main part of the image reading apparatus according to the present embodiment, and FIG. 8 is a block diagram illustrating a configuration of the timing signal generation circuit.
Based on FIG. 7 and FIG. 8, the configuration of the main part of the image reading apparatus and the outline of its operation in the present embodiment will be described below.
A document image is read by photoelectrically converting an optical image of a document 701 to be read by a one-dimensional line sensor (CCD) 702 that is a photoelectric conversion element. The read image signal is subjected to analog processing such as amplification, removal of noise components, and variable amplification for making the white level of the image signal constant in a subsequent analog signal processing circuit 703.
After analog processing, the image signal is converted into digital image data by the A / D conversion circuit 704. In the process of A / D conversion, a scheme is adopted in which the background signal level is set as the quantization reference voltage Vref to perform background removal (background removal). The background signal detected for setting as the reference voltage Vref of the A / D conversion circuit 704 is detected and output by the image signal output from the analog signal processing circuit 703.
[0020]
As a subsequent flow, digital image processing is performed in the image processing block 705 on the image data after A / D conversion. Taking the case of performing shading correction and binarization as an example, γ correction, offset processing, MTF correction, smoothing processing, error diffusion (or dither), isolated point removal, OR processing, etc. are performed to binary data. The image data is output to the using device.
The control unit 707 controls the photoelectric conversion board drive frequency switching signal, the light source lighting control, the FAN motor ON / OFF, the background removal circuit 706, and the entire image reading apparatus.
The timing signal generation circuit 708 is a frequency divider, a frequency switching circuit, a one-dimensional line sensor (CCD) 702, an analog signal processing circuit 703, a background removal circuit 706, a control unit 707, a stepping motor driver 710, and the like. Generate timing signals. Further, the gate circuit 758 performs exclusive control of the drive frequency switching signal and the lighting control signal of the light source.
[0021]
Next, each example will be described in detail. In the first embodiment, in the image reading apparatus, a photoelectric conversion substrate 717 including a photoelectric conversion element 702 and a control substrate 718 are connected via connection cables 714 715 716. Then, the image information of the document 701 is read by the photoelectric conversion element which operates by being supplied with a drive signal from the control board 718 via the connection cable. When the operation clock is stopped during reading standby, the line clamp circuit (not shown) is a circuit that uses charging / discharging of the capacitor. Therefore, when the capacitor voltage is completely discharged such as 0V, normal clamping is performed. It takes time to reach the potential. For this reason, the drive signal frequency 1 is set to 1/16, for example, to the extent that the clamp voltage is not affected by the drive frequency switching means 752 to the photoelectric conversion substrate 717.
This suppresses power consumption and does not affect the clamp potential. Therefore, it is possible to immediately shift to the document image information reading operation by simply switching the driving signal frequency to the driving signal frequency 2 during the document image information reading operation. . Thus, power saving and unnecessary radio wave radiation can be prevented.
In the second embodiment, in the image reading apparatus of the first embodiment, switching to the drive signal frequency 1 is performed even between pages when a plurality of sheets are read. As a result, further power consumption and prevention of unnecessary radio wave radiation can be realized.
[0022]
In the third embodiment, in the first and second embodiments, the period of switching to the drive signal frequency 1 is changed to a frequency spreading coefficient that cannot be used during the reading operation of document image information. By using a coefficient that cannot be used due to image degradation when the image is read, it is possible to prevent unnecessary radiation of radio waves.
In the fourth embodiment, in the image reading apparatus in the first and second embodiments, the analog ASIC signal processing circuit has a normal input characteristic limitation, and the period when the driving signal frequency is switched to 1 is from the photoelectric conversion element. Can easily exceed the limit. Therefore, exclusive control for switching to the drive signal frequency 1 is performed only when the light source is turned off. Even in an analog ASIC signal processing circuit with limited input characteristics, it is possible to realize power saving and prevention of unnecessary radio wave radiation without adding a protection circuit.
In the fifth embodiment, in the image reading apparatus in the first and second embodiments, when a high-speed type photoelectric conversion element is driven at a high speed, a FAN motor 713 for cooling may be mounted. Therefore, since the normal drive signal frequency 1 is in a reading standby state, the power consumption of the photoelectric conversion element substrate can be reduced, and thus the cooling FAN motor 713 is stopped. As a result, further power saving can be realized.
[0023]
【The invention's effect】
According to the first aspect of the present invention, when the first driving signal frequency and the second driving signal frequency are switched depending on whether or not the document image information reading operation is performed, the image reading is performed when the first driving signal frequency is transmitted. Since the means is changed to a frequency spreading coefficient that cannot be used during the reading operation of the document image information, unnecessary radiation of radio waves can be prevented.
According to a second aspect of the present invention, the first drive signal frequency and the second drive signal frequency are switched depending on whether or not the original image information is read, and the control means performs the first drive signal only when the light source is turned off. By switching to the frequency and transmitting, it is possible to realize power saving and prevention of unnecessary radio wave radiation even in an analog signal processing circuit having a limitation on input characteristics .
According to the third aspect of the present invention, when reading a document of a plurality of pages, the control means switches to the first drive signal frequency at the time of reading standby even between pages. Power saving and unnecessary radio wave radiation prevention can be realized.
[0024]
According to the fourth aspect of the present invention, when the control means switches to the first drive signal frequency and sends it out, the cooling fan is not driven, so that further power saving can be realized.
In the invention described in claim 5, it is possible to prevent radiation of unnecessary radio waves.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a digital copying machine according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating an appearance of an automatic document feeder.
FIG. 3 is a view showing a contact glass.
FIG. 4 is a diagram illustrating a document size detection sensor.
FIG. 5 is a block diagram showing a control system of the digital copying machine.
FIG. 6 is a block diagram showing an image processing circuit of a digital copying machine.
FIG. 7 is a block diagram showing a configuration of an image reading apparatus according to the present embodiment.
FIG. 8 is a block diagram showing a configuration of a timing signal generation circuit of the image reading apparatus according to the present embodiment.
FIG. 9 is a block diagram illustrating a configuration of a conventional image reading apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Copier body 10 Contact glass 11 Exposure lamp 500 Operation part controller 501 System controller 502 Image processing controller 503 ADF controller 504 Paper feed tray controller 505 FAX controller 506 Printer controller 600 Document 601 Signal processing circuit 602 AD converter 603 Shading correction circuit 604 Image processing unit 605 Selector 606 Scaling unit 607 Write unit 608 Image memory controller 609 CPU
610 ROM
611 RAM
612 Image memory 613 FAX image memory 614 Printer image memory 701 Document 702 Photoelectric conversion element / primary line sensor 703 Analog signal processing circuit 704 A / D conversion circuit 705 Image processing block 706 Background removal circuit 707 Control unit 710 Stepping motor driver 713 FAN motor 714/715/716 Connection cable 717 Photoelectric conversion board 718 Control board 752 Drive signal frequency switching means 758 Gate circuit 708 Timing signal generation circuit 760 FAN motor

Claims (5)

Image reading means for reading a document image using a photoelectric conversion element;
In the image reading means and the connecting portion are connected via the image comprising a control means, the controlling the image reading means by sending a drive signal via the connection portions reader,
The control means switches between a first drive signal frequency sent via the connection unit during reading standby and a second drive signal frequency sent via the connection unit during a reading operation of document image information. An image reading apparatus that changes the frequency spreading coefficient to a frequency that cannot be used by the image reading means during a reading operation of document image information when the first driving signal frequency is sent out . Image reading means for reading a document image using a photoelectric conversion element;
The image reading means and the connecting portion are connected via a control means for controlling said image reading means by sending a drive signal via the connection portion, the image reading means when reading the original image, the original image In an image reading apparatus comprising a light source for irradiation ,
The control means switches between a first drive signal frequency sent via the connection unit during reading standby and a second drive signal frequency sent via the connection unit during a reading operation of document image information. An image reading apparatus that transmits and switches to the first drive signal frequency only when the light source is turned off . 3. The control unit according to claim 1, wherein when the image reading unit reads a plurality of pages of the document, the control unit switches to the first drive signal frequency during reading standby even between pages. Image reading apparatus. A cooling fan for cooling the image reading means;
4. The image reading apparatus according to claim 1 , wherein the cooling unit is not driven when the control unit switches to the first drive signal frequency and sends the first drive signal frequency. 5.   An image forming apparatus comprising the image reading apparatus according to claim 1, 2, 3, or 4.

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