JP2004109227A - Image reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reader capable of decreasing the error deviation of subscanning magnification and reducing trapezoidal image deformation. <P>SOLUTION: In the image reader 200 reading the image of an original by a plurality of one-dimensional line sensors, both sides of carriages 203 and 204 are driven by independent driving means 207 respectively, and the driving means of the carriages 203 and 204 are stepping motors 207, and the rotating speed of either driving motor 207 is adjusted by a fine adjustment control means for the deviation of the subscanning magnification. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image reading apparatus that reads image information while moving an image reading apparatus carriage in a sub-scanning direction.
[0002]
[Prior art]
2. Description of the Related Art An image reading apparatus of an image forming apparatus reads an original while scanning a surface of an original placed on a contact glass of an original plate with a one-dimensional line sensor moving along the back of the contact glass. Have been. Here, the scanning of the image reading device is performed by a bearing that contacts the contact glass, a carriage that holds the sensor and the illumination member, a spring member that presses the carriage against the contact glass, and a guide that holds the carriage and is guided by a central guide shaft. And a carriage holding member having a bearing portion. Further, as a driving method of the carriage of the image reading apparatus, a driving pulley is provided at both ends of a driving shaft, a drive is transmitted by a wire or a timing belt, and the carriage is driven in the sub-scanning direction. You are traveling along. In the case of this driving method, a deviation in the sub-scanning magnification error occurs due to a variation in the tolerance of the outer shape of the driving pulley provided on the driving shaft or a variation in the pitch of the timing belt, and a trapezoidal image may be formed.
[0003]
Therefore, for example, Patent Literature 1 discloses a traveling body control unit of an image reading apparatus that can perform speed control of a traveling body without a speed deviation from a target speed by a linear motor. Patent Document 2 discloses a means for controlling acceleration and deceleration of a motor, and a clock cycle changing means for changing a clock cycle of main scanning according to the rotation speed of the motor during acceleration or deceleration before and after the motor maintains a constant speed. An image reading apparatus is disclosed in which an image can be read at the time of acceleration or deceleration.
However, in the image reading apparatuses disclosed in Patent Document 1 and Patent Document 2, the control becomes complicated, and it is not enough to prevent the deviation in the sub-scanning magnification error.
[Patent Document 1]
JP-A-09-219986 [Patent Document 2]
JP 2001-257845 A
[Problems to be solved by the invention]
In view of the above, the present invention has been made in view of the above circumstances. By controlling the driving on both sides of the carriage by independent driving means, the deviation in the sub-scanning magnification error is reduced, and the trapezoidal image deformation is reduced. It is an object to provide an image reading device capable of causing the image reading device to read the image. Further, the present invention provides an image reading apparatus in which the driving on both sides is controlled by independent driving means. However, when an abnormality occurs on one driving means, the carriage is prevented from tilting and mechanical damage is generated. That is the task. Further, it is an object of the present invention to provide an image reading apparatus in which each of the independent driving means is a stepping motor, and the rotational speed of each of the driving motors can be controlled to be finely adjusted so that the deviation in the sub-scanning magnification error can be reduced. Make it an issue.
[0005]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided an image reading apparatus for reading a document image by using a plurality of one-dimensional line sensors, wherein the image reading device drives each side of a carriage independently. An image reading device driven by means.
According to a second aspect of the present invention, in the image reading apparatus according to the first aspect, the image reading apparatus is configured to perform an emergency stop when one of the drive units of the carriage has an abnormality. It is.
According to a third aspect of the present invention, in the image reading apparatus according to the first aspect, the driving means of the carriage is a stepping motor, and the rotational speed of one of the driving motors is set to a sub-scanning magnification deviation. The image reading device is adjusted by the fine adjustment control means.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a digital copying machine which is an image forming apparatus on which the image reading apparatus of the present invention can be mounted. An image reading apparatus according to the present invention will be described based on this digital copying machine.
The mechanism of the image forming apparatus roughly includes a copying machine main body 1, an automatic document feeder (ADF) 100, an in-body discharge tray 110, and a paper feed unit (bank) 300. The automatic document feeder 100 feeds the documents stacked on the document feed table 101 one by one onto the contact glass 10 of the copying machine main body 1, and discharges the document onto the discharge tray 105 after reading the image. It is configured.
[0007]
The document on the document feeder table 101 is aligned in the width direction by a side fence (not shown), separated from the uppermost document by a feed roller 102, fed, and fed onto the contact glass 10 by a transport belt 103. Paper. Further, the feeding section 107 is provided with a document width detection sensor 108 and a document length detection sensor 109. The size of the document sent from the automatic document feeder 100 is detected by both sensors 108 and 109. After the reading of the original on the contact glass 10 is completed, the original is discharged onto a discharge tray 105 by a transport belt 103 and a discharge roller 104.
When reading a double-sided document, the document on the document feed table 101 is separated from the top document by the feed roller 102 and fed, and passes over the contact glass 10 by the transport belt 103. The sheet is reversed by the reversing claw 106, fed again onto the contact glass 10, and the back surface is read. Next, after the reading of the back surface of the contact glass 10 is completed, the original is conveyed by the conveyance belt 103 and inverted by the reversing claw 106, and is again fed onto the contact glass 10 to read the front surface. Then, the document after the front surface reading is completed is discharged onto a discharge tray 105 by the transport belt 103 and the discharge roller 104.
[0008]
FIG. 2 is a schematic diagram showing an upper configuration of an image forming apparatus on which the image reading apparatus of the present invention can be mounted.
As shown in FIG. 2, the automatic document feeder 100 is opened and closed about hinges 81 and 82, and a claw 83 is provided near the hinge 81 on the upper surface of the copying machine main body 1. A hole 84 is provided on the lower surface of the automatic document feeder 100 at a position where the claw 83 faces when the transporting device 100 is closed, and the claw 83 is inserted into the hole 84 when the automatic document feeder 100 is closed. ing. 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 a claw 83 inserted into the hole 84 are provided. The lift-up detection sensor 85 detects the claw 83 when the automatic document feeder 100 is completely closed (lift-down) and is turned on, and when the automatic document feeder 100 is open (lift-up). To the OFF state. Note that the completely closed state refers to a state where 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.
[0009]
On the other hand, the document detection timing sensor 86 is provided to control the timing of detecting the size of the document on the contact glass 10 based on the detection result of the document size detection sensor described later. When the opening angle is less than a predetermined angle, the claw 83 is detected and turned on. In addition, 87 and 88 are end face scales.
[0010]
FIG. 3 is a schematic diagram showing an arrangement of a document size detection sensor in the image reading apparatus of the present invention. FIG. 4 is a view for explaining the situation of reading the document size in FIG. 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 into three beams and irradiates the reflected light with three beams inside the optical system. This is a reflection type sensor that receives light with the light receiving element 91b, and detects only the reflected light from the document surface through the contact glass 10 from inside the optical system to detect the presence or absence of the document.
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 no document is 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. Thus, it is determined whether or not the original is on the contact glass 10 and the size of the original on the contact glass 10 is detected.
[0011]
The copier main body 1 includes an image reading device 200 for reading a document, an image processing unit, a plotter unit, and the like. The image reading apparatus 200 has a contact glass 10 for placing a document and an optical scanning system, and the optical scanning system includes an exposure lamp 11, a first mirror 12, a second mirror 13, a third mirror 14, a lens 15, a full color It has a CCD 16 and the like.
The exposure lamp 11 and the first mirror 12 are mounted on a first carriage, and the first carriage is moved 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 a second carriage, and the second carriage is moved by a stepping motor at half the speed of the first carriage when reading a document. The original on the contact glass 10 is optically scanned by the movement of the first and second carriages, and is imaged on the light receiving surface of the CCD 16 by the lens 15 and photoelectrically converted.
[0012]
The image signals separated into red (R), green (G), and blue (B) by the full-color CCD 16 are subjected to A / D conversion and the like by an image processing circuit, and then subjected to various image processing by an image processing unit 604. Then, at the time of copying, it is copied onto recording paper by a writing unit. The writing unit has laser output units 20 and 25, an fθ lens 21, mirrors 22, 23, 24, 26 and 27. The laser output units 20 and 25 include a laser diode (LD) as a laser light source and a polygon (not shown). It has a mirror and a polygon motor. At the time of copying, the laser output units 20 and 25 emit black and red laser light modulated according to the image read by the image reading device 200, and a latent image is formed on the photoconductor 30. Around the photoconductor 30, a black developing device 32, a red second developing device 33, a transfer / transport device 54, a separator (not shown), and the like are arranged, and a toner image on the photoconductor 30 is recorded on a sheet.
The recording paper is selectively supplied from the duplex unit 40 and the first tray 50 in the copier body 1 and one of the second tray 310, the third tray 320, and the fourth tray 330 in the paper feed unit 300. The sheet is fed by a pair of rollers of a reversible roller 42 and a contacting / separating roller 43, a first sheet feeding device 51, a second sheet feeding device 311, a third sheet feeding device 321 and a fourth sheet feeding device 331, respectively.
[0013]
FIG. 5 is a view for explaining detection of the size of the recording paper in the image reading apparatus of the present invention. FIG. 6 is an enlarged view of a part of FIG. As shown in FIG. 5, the size and the setting direction of the recording paper set in each tray are detected by a combination of ON / OFF of a plurality of push switches 401 in a position of a size lever 400 in the tray. The paper fed from each tray abuts against the registration roller 53 a predetermined time after the leading edge is detected by the registration sensor 52, temporarily stops, and is synchronized with the sub-scanning effective period signal (FGATE) by the registration roller 53. The toner image on the photoconductor 30 is transferred by the transfer and transfer 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 the fixing is discharged to the in-body discharge tray 110 by the switching claw 57 and the discharge roller 56 during the one-sided printing and after the two-sided printing.
On the other hand, the paper after the back side printing during the duplex printing is guided to the duplex transport path 41 by the switching claw 57, inverted by the reversible rollers 42 and the contact / separation rollers 43, and transported into the duplex unit 40. The paper in the duplex unit 40 is sent to the vertical transport unit, where an image is formed on the surface.
[0014]
FIG. 7 is a block diagram showing a control system in an image forming apparatus on which the image reading apparatus of the present invention can be mounted. As shown in FIG. 7, the operation unit controller 500 performs display control of liquid crystal and various LEDs of the operation unit, and various key input controls, and the system controller 501 performs sheet feeding, conveyance, fixing, double-sided printing, process control, and the like.
The image processing controller 502 performs image control and reading control of the image reading device 200, and the ADF controller 503 controls the automatic document feeder 100. The paper feed tray controller 504 controls a paper feed tray, the FAX controller 505 manages FAX transmission and reception, and file management, and the printer controller 506 manages printer data reception and file management.
[0015]
FIG. 8 is a block diagram showing an image processing circuit in an image forming apparatus on which the image reading device of the present invention can be mounted. The original 600 on the contact glass 10 is illuminated by the exposure lamp 11 and the reflected light is read by the color CCD 16. Next, the analog image signal separated into R, G, and B by the color CCD 16 is amplified by the signal processing circuit 601 to correct the light amount, is converted to a digital image signal by the AD converter 602, and is corrected by the shading correction circuit 603. The image data is sent to the image processing unit 604.
[0016]
The image processing unit 604 performs image quality processing such as MTF correction, γ correction, black image generation, color image generation, binary processing, and multi-value processing, and outputs black data and color 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 scaled according to the scaling factor and sent to the writing unit 607. The image memory controller 608 and the selector 605 are configured to be able to input and output image signals in both directions. The image processing apparatus further includes a CPU 609 for setting the image memory controller 608 and the like and controlling a reading unit and a writing unit, and a ROM 610 and a RAM 611 for storing the programs and data. Further, the CPU 609 can write and read data in the image memory 612 via the memory controller 608. The original image sent to the image memory controller 608 is sent to the image memory 612 after the image data is compressed by an 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 number of document image data can be stored at one time, the stored document image data can be output in page order. In this case, when the image is output, the data is output while sequentially expanding the data in the image memory 612 by the expansion device in the memory controller 608. The document image image data stored in this way is output in page order, the document image is rotated by the number of copies, and output on a recording sheet.
On the other hand, during fax transmission, the selector 605 transfers the black data to the fax image memory 613. Further, at the time of FAX reception, after the received data is demodulated and expanded from the line, expanded in the FAX image memory 613, the data is sent to the writing unit 607 by the selector 605.
Further, upon receiving the printer data, the data is expanded in the printer image memory 614 and then sent to the writing unit 607 by the selector 605.
[0017]
FIG. 9 is a block diagram of the image reading apparatus of the present invention. With reference to FIG. 9, the configuration of the main part and the outline of the operation will be described. The original image is read by photoelectrically converting an optical image of the original 801 to be read by a photoelectric conversion element and a one-dimensional line sensor 802 of a two-line CCD. An analog signal processing circuit 803 at the subsequent stage performs analog processing such as amplification, removal of a noise component, and variable amplification for stabilizing the white level of the image signal on the read image signal of the first line read first. After the analog processing, the image signal is converted into digital image data by the A / D conversion circuit 804. In the process of A / D conversion, a method is employed in which the background signal level is set as the quantization reference voltage Vref to remove the background (skip the background). A background signal detected to be set as the reference voltage Vref of the A / D conversion circuit 804 is detected and output as an image signal output from the analog signal processing circuit 803.
The second and subsequent lines are converted into digital image data by the A / D conversion circuit 816 by the analog signal processing circuit 815 and the reference voltage Vref obtained on the first line. A line delay circuit 813 and a line synthesizing circuit / color separating circuit 814 that perform line alignment of the read image data overlap the luminance of the same read image and generate a color identification signal. In the subsequent flow, digital image processing is performed in the image processing block 805 on the image data after the A / D conversion.
[0018]
For example, when shading correction and binarization processing are performed, γ correction, offset processing, MTF correction, smoothing processing, error diffusion (or dither), isolated point removal, OR processing, and the like are performed to generate binary data. And outputs the image data to the use device.
An MCU (main control unit) 807 controls the background removal circuit 806 and the entire image reading apparatus 200. The timing signal generation circuit 808 generates various timing signals to the one-dimensional line sensor 802, analog signal processing circuits 803 and 815, background removal circuit 806, MCU 807, stepping motor driver 810, lamp inverter, and the like.
[0019]
FIG. 10 is an explanatory diagram showing a main configuration of a conventional image reading apparatus. Reference numeral 201 denotes an exposure lamp serving as a light source for illuminating the document, reference numeral 202 denotes a first mirror that guides reflected light of the document illuminated by the exposure lamp 201, reference numeral 203 denotes a document integrally configured with the exposure lamp 201, the first mirror 202, and the like. The first carriage 204 scans the original by integrally forming the second mirror and the third mirror, and guides the reflected light from the first carriage 203 to the imaging lens 205. An image forming lens for forming an image on the next image sensor 206; an image sensor (solid-state imaging device: CCD) 206 for converting the reflected light of the received document into an electric signal; and a scanning unit 207 for scanning the first carriage 203 and the second carriage 204 This is a stepping motor for driving, and uses a three-phase stepping motor. Reference numeral 208 denotes a first drive belt that scans and drives the first carriage 203, 209 denotes a second drive belt that scans and drives the second carriage 204, and 210 denotes a stepped pulley that transmits drive to the first drive belt 208 and the second drive belt 209. , 211 are idle pulleys that stretch freely around the first drive belt, 212 are idle pulleys that stretch freely around the second drive belt, and 213 transmits the driving force of the stepping motor 207 to the drive shaft 214. A drive belt 214 is a drive shaft that rotates while coaxially fixing the stepped pulley 210 on both sides, and 215 is a drive pulley provided on the drive shaft 214 and transmitting a rotational force to the drive shaft 214 by the drive belt 213.
In the above configuration, the second carriage 204 moves at half the speed of the first carriage 203 because the optical path length formed on the image sensor 206 is turned back by the second mirror and the third mirror to be constant. In this case, the rotation ratio of the stepped pulley 210 is set to 1: 2.
[0020]
In the image reading apparatus 200 configured as described above, the rotation of the stepping motor 207 transmits a rotational force to the driving pulley 215 via the driving belt 213. When the rotational force is transmitted to the driving pulley 215, the stepped pulley 210 is rotated by the driving shaft 214, and at the same time, the first driving belt 208 and the second driving belt 209 are rotated, and the first carriage 103 and the second carriage 204 are moved. Move each. At this time, the exposure lamp 203 is turned on to expose and scan a document (not shown), and the reflected light is guided from the first mirror 201 to the imaging lens 205 by the second mirror and the third mirror of the second carriage 204, An image is formed on the image sensor 206 by the imaging lens 205 and is converted into an electric signal.
[0021]
Next, the present invention will be described with reference to examples.
FIG. 11 is a schematic diagram showing the configuration of the image reading apparatus according to the present invention. Although the configuration is almost the same as that of FIG. 10, both ends of each stepped pulley 210 are rotationally driven by a stepping motor 207 for applying a rotational force only to the stepped pulley. Each drive motor is driven and controlled by applying a standard number of reference pulses from a control unit. When a conveyance speed deviation in the sub-scanning direction occurs due to a pitch error of the timing belt, a sub-mode is set in a mode in which parameters can be set in the image forming apparatus by a serviceman or a user (hereinafter, referred to as “SP mode”). The scanning speed deviation fine-adjustment input means can change the speed of one of the drive motors to control the same speed so that the skew of the first and second carriages can be corrected. Therefore, distortion such as trapezoidal deformation of the image can be prevented.
By providing drive motors at both ends, the load of the drive load is reduced to half that of the conventional one, so the rated load torque of the drive motor is reduced, and the size of the drive motor can be reduced, resulting in low cost and space saving. Can be achieved.
[0022]
【The invention's effect】
As described above, in the image reading apparatus of the present invention, by controlling the driving on both sides by independent driving means, the deviation in the sub-scanning magnification error can be reduced and the image distortion such as a trapezoidal image can be corrected. Further, since the driving torque can be reduced to half of the conventional one, the size of the driving motor can be reduced, so that the cost and space can be reduced.
Further, in the image reading apparatus of the present invention, the driving on both sides is controlled by independent driving means, respectively.However, when an abnormality occurs on one driving means, the carriage is tilted and the occurrence of mechanical damage is prevented. Can be prevented.
Further, in the image reading apparatus of the present invention, the independent driving means is a stepping motor, and the rotational speed of each of the driving motors is controlled so as to be able to be finely adjusted so as to reduce the deviation in the sub-scanning magnification error, thereby reducing the trapezoidal image. And other image distortions can be corrected.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of a digital copying machine which is an image forming apparatus on which an image reading apparatus of the present invention can be mounted.
FIG. 2 is a schematic diagram showing an upper configuration of an image forming apparatus on which the image reading apparatus of the present invention can be mounted.
FIG. 3 is a schematic diagram showing an arrangement of a document size detection sensor in the image reading apparatus of the present invention.
FIG. 4 is a diagram for explaining a situation of reading a document size in FIG. 3;
FIG. 5 is a diagram for explaining detection of a size of a recording sheet in the image reading apparatus of the present invention.
FIG. 6 is an enlarged view of a part of FIG. 5;
FIG. 7 is a block diagram showing a control system in an image forming apparatus on which the image reading apparatus of the present invention can be mounted.
FIG. 8 is a block diagram illustrating an image processing circuit in an image forming apparatus in which the image reading device of the present invention can be mounted.
FIG. 9 is a block diagram of the image reading apparatus of the present invention.
FIG. 10 is an explanatory diagram showing a main configuration of a conventional image reading apparatus.
FIG. 11 is a schematic diagram illustrating a configuration of an image reading apparatus according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Copier main body 10 Contact glass 11 Exposure lamp 12 First mirror 13 Second mirror 14 Third mirror 15 Lens 16 Full color CCD
20, 25 laser output unit 21 fθ lens 22, 23, 24, 26, 27 mirror 30 photoreceptor 32 black developing device 33 red second developing device 40 double-sided unit 42 reversible roller 43 contacting / separating roller 50 first tray 51 first 1 paper feeder 53 registration roller 54 transfer device 55 fixing device 56 discharge roller 57 switching claw 81, 82 hinge 83 claw 84 hole 85 lift-up detection sensor 86 document detection timing sensor 87, 88 end face scale 91, 92, 93 document size Detection sensor 91a light emitting diode 91b light receiving element 100 automatic document feeder 101 document feeder table 102 feed roller 103 transport belt 104 discharge roller 105 discharge tray 106 reversing claw 107 paper feed section 108 document width detection sensor 109 document length detection Sensor 110 Internal discharge tray 200 Image reading device 01 exposure lamp (light source)
202 First mirror 203 First carriage 204 Second carriage 205 Imaging lens 206 Image sensor 207 Stepping motor 208 First drive belt 209 Second drive belt 210 Stepped pulley 211, 212 Idle pulley 213 Drive belt 214 Drive shaft 215 Drive pulley 300 sheet feeding unit 310 second tray 311 second sheet feeding device 320 third tray 321 third sheet feeding device 330 fourth tray 331 fourth sheet feeding device 400 size lever 401 push switch 500 operating unit 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 Funding correction circuit 604 the image processing unit 605 selector 606 scaling unit 607 writing unit 608 the image memory controller 609 CPU
610 ROM
611 RAM
612 Image memory 613 FAX image memory 614 Printer image memory 801 Document 802 Line sensor 803, 815 Analog signal processing circuit 804, 816 AD conversion circuit 805 Image processing block 806 Background removal circuit 807 MPU
808 Timing signal generation circuit 810 Stepping motor driver 813 Line delay circuit

Claims (3)

In an image reading apparatus that reads an original image by using a plurality of one-dimensional line sensors,
The image reading apparatus is characterized in that both sides of the carriage are driven by independent driving means, respectively. The image reading device according to claim 1,
The image reading apparatus is characterized in that, when an abnormality occurs in one of the carriage driving means, an emergency stop is performed. The image reading device according to claim 1,
In the above image reading apparatus, the carriage driving means is a stepping motor, and the rotation speed of one of the driving motors is adjusted by a sub-scanning magnification deviation fine adjustment control means.

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