JPH0583489A - Image reader and image copy device - Google Patents

Abstract

PURPOSE:To execute the high-speed reciprocative reading operation of a line sensor with the memory of small capacity and to execute high-speed and continuous copy recording with the memory of small capacity. CONSTITUTION:The output of a velocity detecting circuit 18 is detected by a sampling circuit 19 and corresponding to the detected scanning velocity, the light storage time of a line sensor 1 is changed according to a signal from a sensor driving circuit 5. Under the control of a control part 11, a signal processing circuit 6 amplifies the output of the line sensor 1 corresponding to the scanning velocity, further, the correcting value of a black level signal is changed corresponding to the amplification factor and moreover, the correcting value of the black level signal is changed corresponding to the temperature change due to the output of a temperature detecting sensor 20. The sub scanning velocity of the line sensor 1 is changed corresponding to a copy size designated by a copy original selection part 17 and further, image data are successively stored in a buffer memory 7 and successively outputted to a printer 14. Equal-size copy is executed while accelerating the read sub scanning velocity of the line sensor 1 rather than the sub scan recording velocity of the printer 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus for reading and scanning an original image by a line sensor, and an image copying apparatus having such a reading scanning unit.

[0002]

2. Description of the Related Art In recent years, the recording speed has been increasing with the improvement of image recording technology. On the other hand, since the image reading speed must include not only the actual image reading, but also the acceleration / deceleration and return of the scanner because the scanner is reciprocally moved for reading, there is a limit to the speeding up. There is.

Therefore, there is a problem in that it is difficult to increase the speed of continuous recording operation in copying a large number of originals and further copying a large number of originals. In order to solve this problem, currently, in the case of copying a large number of one original, an image read by a scanner is temporarily stored in a page memory, and this is repeatedly read and recorded (for example, Japanese Patent Publication No. 2-28867). No.) has been adopted.

[0004]

In the above-mentioned prior art, the page memory is effective for continuous recording of one original at high speed, but many originals other than continuous recording of one original are used. In the case of continuous copying of a large number of sheets, the time required for exchanging originals also becomes an issue, and high-speed copying is not always possible only by using a large capacity memory such as a page memory. Therefore, the conventional technique has a problem that a large-capacity memory called a page memory is used without being effectively utilized.

In view of the above points, the present invention makes effective use of a small-capacity memory to perform high-speed recording even during continuous recording in the case where a large number of originals are copied and a large number of originals are copied. The main purpose is to provide a new technology that can be done.

[0006]

In order to achieve the above object, an image reading apparatus according to the present invention comprises an image reading line sensor for reading a document line by line and converting it into digital image data, and a read image of at least one line. Storing means, a sub-scanning means for accelerating and controlling the image reading line sensor to a recording scanning speed equal to or higher than the recording scanning speed of the image data output device, and the image reading in the sub-scanning direction. First control means capable of controlling the reading start line and the end line of the line sensor in relation to the sub-scanning speed of the image reading line sensor, and the image of the effective range of the image of one line read by the image reading line sensor To be sequentially stored in the storage means at a constant time equal to or shorter than the minimum value of the reading cycle of one line. With Gosuru is characterized in that it comprises a second control means to sequentially read out line by line from the memory means in accordance with a recording scan speed of the output device.

Here, the output device is a printer, and the sub-scanning means can change the sub-scanning speed of the image reading line sensor according to the document size. The image reading device further includes an image reading line sensor.
Timing generating means for generating a timing signal for determining a cycle for reading a line, and a generation interval of the timing signal are set so that a constant resolution can be obtained even if the sub-scanning speed of the image reading line sensor is changed. And a timing control means for changing the timing according to the above.

The image reading device further includes speed detecting means for detecting the sub-scanning speed of the image reading line sensor, and the timing signal generation interval can be controlled by the detection result. The first control means, when the timing signal generation interval is within the control range from the minimum value to the maximum value controlled by the timing control means,
Start the image reading by the image reading line sensor,
When it is out of the control range, the image reading is controlled to end.

The second control means only stores the image data during the period when the image reading line sensor is accelerated in the sub-scanning direction, and the image reading line sensor scans at a constant speed or decelerated in the sub-scanning direction. After that,
Image data can be read. The storage means sets the difference between the read image data amount sequentially input from the image reading line sensor and the output image data amount sequentially read line by line from the storage device according to the recording scanning speed of the output machine as the maximum stored data amount. be able to.

The image reading apparatus further includes an amplification means for amplifying the output image signal of the image reading line sensor, and an amplification control means for changing the amplification amount of the amplification means according to the generation interval of the timing signal by the timing generation means. And may be provided. The image reading device further includes a black level correction unit that corrects a black level signal of the image reading line sensor, and a correction control unit that changes a correction value of the black level correction unit according to an amplification amount of the amplification unit. May be.

The image reading apparatus further includes a black level correcting means for correcting the black level signal of the image reading line sensor, a temperature when the black level correction of the image reading line sensor is performed, and a temperature during scanning of reading an original. And a correction control unit that changes the correction value of the black level correction unit according to the amplification amount of the amplification unit and the temperature change amount detected by the temperature detection unit. Good.

In order to achieve the above object, the image copying apparatus of the present invention is an image reading line sensor for reading a document line by line and converting it into digital image data, and a memory capable of storing at least one line of read images. Means, recording means for reading from the storage means and recording at a constant recording scan speed, and sub-scanning for accelerating control of the image reading line sensor to a recording scan speed equal to or higher than the recording scan speed of the recording means. Means, and a first control means capable of controlling the reading start line and the end line of the image reading line sensor in the sub scanning direction in relation to the sub scanning speed of the image reading line sensor, and the image reading line sensor. The image of the effective range of the image of 1 line is set to the same value as the minimum value of the reading period of 1 line or a fixed time shorter than that. Controls to store sequentially the storage means is characterized by comprising a second control means to sequentially read from the storage means by one line in accordance with a recording scan speed of the recording means.

Here, the image copying apparatus further includes a designating unit for designating a copy document size, and the sub-scanning unit can change the sub-scanning speed of the image reading line sensor according to the designated document size. .. The image copying apparatus further includes a timing generation unit that generates a timing signal that determines a period for the image reading line sensor to read one line, and a generation interval of the timing signal when the sub-scanning speed of the image reading line sensor is changed. However, it may have timing control means for changing it in accordance with the sub-scanning speed so as to obtain a constant resolution.

The image copying apparatus further includes speed detecting means for detecting the sub-scanning speed of the image reading line sensor,
The timing signal generation interval can be controlled by the detection result. When the timing signal generation interval is within the control range from the minimum value to the maximum value controlled by the timing control means, the first control means starts the image reading by the image reading line sensor, and goes out of the control range. At some time, control is performed so as to end the image reading.

The second control means only stores image data while the image reading line sensor is accelerated in the sub-scanning direction, and the image reading line sensor scans at a constant speed or decelerated in the sub-scanning direction. After that,
Image data can be read. The storage means stores a value of 1 according to the amount of read image data sequentially input from the image reading line sensor and the recording scan speed of the recording means.
The difference between the output image data amounts sequentially read line by line can be set as the maximum stored data amount.

The image copying apparatus further includes an amplifying means for amplifying the output image signal of the image reading line sensor, and an amplifying control means for changing the amplification amount of the amplifying means according to the generation interval of the timing signal by the timing generating means. And may be provided. The image copying apparatus further includes a black level correction unit that corrects a black level signal of the image reading line sensor, and a correction control unit that changes a correction value of the black level correction unit according to an amplification amount of the amplification unit. May be.

The image reading apparatus further includes a black level correcting means for correcting a black level signal of the image reading apparatus line sensor, a temperature when the black level correction of the image reading line sensor is performed, and a temperature during scanning of reading an original. And a correction control unit that changes the correction value of the black level correction unit according to the amplification amount of the amplification unit and the temperature change amount detected by the temperature detection unit. Good.

[0018]

According to the present invention, the sub-scanning means accelerates the image reading line sensor to a printing scanning speed higher than the printing scanning speed of the image data output machine, and the second control means reads data from the storage means. Data writing is performed within a period of one line reading cycle by the line sensor, and reading from the storage means is performed according to the recording scanning speed of the image data output device.

Therefore, the storage means only needs to store the difference between the image data generated by scanning the original by the image reading line sensor and the image data sent to the output device, and a small capacity memory can be used. Moreover, since the reading start line and the end line when the image reading line sensor is sub-scanned once by the first control means are controlled according to the sub-scanning speed of the image reading line sensor, the image reading line sensor's addition Images can be read even in the deceleration section. Therefore, the image reading amount in one sub-scan can be increased,
In other words, if the same amount of image data can be read in a short sub-scanning time, a single original document is copied multiple times, and further continuous recording for multiple original document copies is repeated by the image reading line sensor. It can be executed at high speed even if it is performed while sub-scanning.

Further, by providing the timing control means, the generation interval of the timing signal of the timing generation means can be changed according to the scanning speed of the image reading line sensor. As a result, the image reading line sensor can read and scan with a constant sub-scanning resolution even if the scanning speed changes. Further, by providing the amplification control means, the amplification amount of the amplification means can be changed according to the generation interval of the timing signal by the timing generation means. As a result, the analog image signal before quantization is controlled to a predetermined level and can be accurately quantized even if the generation interval of the timing signal to the reading line sensor by the timing generating means changes.

Further, by providing the correction control means, the correction value of the black level correction means can be changed according to the amplification amount of the amplification means. As a result, it is possible to eliminate an error in the correction value of the black level signal of the image reading line sensor stored before the scanning of reading the original, which is caused by the change of the amplification amount of the amplifying means, and the amplification amount is re-read during the scanning of reading the original. Depending on the setting, it is not necessary to store the correction value again.

Further, if the correction control means changes the correction value of the black level correction means in accordance with the amplification amount of the amplification means and the temperature change amount detected by the temperature detection means, the original reading scanning is performed. It is possible to eliminate an error caused by a change in the amplification amount of the amplifying means and an error caused by a temperature change in the correction value of the black level signal of the image reading line sensor, which is stored before, and the amplification amount is reset during the scanning for reading the original. It becomes unnecessary to store the correction value again due to the setting and the temperature change.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image reading apparatus and an image copying apparatus according to an embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram of an image reading apparatus and an image copying apparatus according to an embodiment of the present invention.

In FIG. 1, the reflected light image of the original 13 placed on the platen glass 12 exposed and scanned by the light source 3 is formed by the lens unit 2 on each light receiving element on the line sensor 1. The line sensor 1 is, for example, CC
The formed original image is converted into an analog image signal by using a photoelectric conversion element used in a D camera or the like. Although the photoelectric conversion element is shown in FIG. 1 as an example of a contact type, a reduction type may be used. In the reduction type, a plurality of reflection mirrors are used to guide the reflected light image to the reduction lens, and the reflection after passing through the reduction lens. The light image is reduced and formed on the line sensor 1. Further, the line sensor 1 outputs an analog image signal to the signal processing circuit 6 in synchronization with the transfer pulse SH output from the sensor drive circuit 5 and the pixel clock SCLK.

The signal processing circuit 6 amplifies the analog image signal output from the line sensor 1 and further a built-in A /
The D converter converts the analog image signal into a digital image signal. Also, black level correction of digital image signals,
The white level is corrected, the density of the linear reflectance signal is converted into the density linear signal, and the signal is output to the buffer memory 7. The correction coefficient of the black level correction is corrected and controlled by the controller 11 according to the output value of the temperature detection sensor 20 attached to the line sensor 1.

The sensor drive circuit 5 generates a transfer pulse SH for transferring the charges of the photosensitive portion of the line sensor 1 to the output shift register, a pixel clock SCLK synchronized with the transfer pulse SH, and an image valid signal SEN. It outputs to the line sensor 1, the controller 11, and the sampling circuit 19. The cycle of the transfer pulse SH is the accumulation time of the optical signal of the line sensor 1.

The carriage unit 4 is a casing having the line sensor 1, the lens unit 2 and the light source 3 and movable in the backward scanning direction. The movement to the sub-scan is performed by the motor unit 8 described below. The motor unit 8 includes a drive motor 8a, a rotary encoder 8c attached to the drive shaft of the drive motor 8a, and a detection sensor 8b that detects a slit of the rotary encoder 8c and generates a pulse.

During the scanning for reading the original, the motor control circuit 1
0 is the speed designation from the controller 11, the scanning range designation,
The motor 8a is driven and controlled by a control signal such as a drive designation and the carriage unit 4 for moving the light source 3, the lens unit 2 and the line sensor 1 as a unit is moved, and the line sensor 1 is moved to the start position P2 of the original 13. From the end position P3 to the end position P3 in the sub-scanning direction. As a result, the line sensor 1 can repeatedly read and scan the original 13 from the start position P2 to the end position P3. During the correction operation of the signal processing circuit 6, the motor control circuit 10 drives and controls the motor 8a in accordance with the control signal from the controller 11, moves the line sensor 1 to the position P1 of the reference white plate 16 for shading correction, and stops it. After the correction processing of the signal processing circuit 6 is completed, the line sensor 1 is moved to the start position and stopped.

The position detection circuit 9 initializes an internal position signal by the position sensor 15 attached to the reference position P0, and outputs a relative position signal indicating the movement amount of the line sensor 1 from the reference position P0 to the motor control circuit 10. .. The relative position signal is generated by detecting the pulse from the rotary encoder 8c attached to the drive shaft of the motor 8a.
This is performed by counting the number of detected pulses. The motor control circuit 10 can detect the position P1 of the reference white plate 16, the start position P2, the end position P3 of the original 13, and the position of the line sensor 1 with respect to the original 13 from the relative position signal.

The speed detection circuit 18 counts the pulse cycle output from the sensor 8b with an internal clock to generate a sub-scanning speed signal V, which is output to the motor control circuit 10 and the sampling circuit 19. The motor control circuit 10 drives the motor 8a based on the difference between the sub-scanning speed Vx set by the controller 11 and the speed signal V so that the sub-scanning speed of the carriage unit 4 to which the line sensor 1 is attached becomes constant at the set value Vx. Control.

The sampling circuit 19 is the sensor drive circuit 5
The speed signal V is sampled in synchronization with the transfer pulse SH output from The copy manuscript selector 17 has LETTE
A plurality of selection buttons for designating the copy size such as R and LEDGER are prepared. The operator can specify the copy size and start the copy operation by pressing any of the plurality of selection buttons. When the copy size is designated, the copy document selecting section 17 outputs data for setting the copy size to the controller 11.

When the copy size data is input from the copy manuscript selection unit 17, the controller 11 sends a processing value corresponding to the copy size to the sensor drive circuit 5, the signal processing circuit 6, the buffer memory 7, and the motor control circuit 10. Set.
After the setting, the copy size and the recording start signal are transmitted to the printer 14, and the control signal is output to the motor control circuit 10 in synchronization with the sub-scanning synchronous position signal (hereinafter referred to as VSYNC) of the recording paper output from the printer 14. To do. Further, VSYNC output from the printer 14, a raster scanning synchronization signal (hereinafter simply referred to as HSYNC), and a pixel clock (hereinafter simply referred to as PCLK) synchronized with HSYNC are input, and a control signal is output to the buffer memory 7. To do. Further, the controller 11 transfers the transfer pulse SH from the sensor drive circuit 5 and the pixel clock SC synchronized with the transfer pulse SH.
A control signal is output to the signal processing circuit 6 and the buffer memory 7 in accordance with LK and the image valid signal SEN, and digital image signals are sequentially stored in the buffer memory 7.

FIG. 9 shows the detailed structure of the controller 11. As shown in the figure, the controller 11 is the CPU 1
10, a RAM 111, a ROM 112, and an I / O port 113. The buffer memory 7 sequentially stores the digital image signal output from the signal processing circuit 6 according to the control signal of the controller 11, and sequentially outputs the digital image signal output to the printer 14. The detailed structure of the buffer memory 7 is shown in FIG.

The printer 14 is, for example, a laser beam printer based on an electrophotographic process, and a laser beam signal modulated by an input image signal is exposed and scanned on a photoconductor charged on the entire surface by raster scanning at a constant speed. An electrostatic latent image is formed, and the image forming portion is developed by a developing device. The developed toner of the image forming portion is transferred to the paper, and the toner on the paper is fixed to the paper by the fixing device. By repeating the processes of charging, exposing, developing, transferring and fixing in this way, the input image signal is continuously recorded on the paper. The printer 14 has VSYNC, HSYNC, and H
The PCLK synchronized with SYNC is output to the controller 11. The printer 14 selects a recording sheet according to the copy size transmitted from the controller 11 and repeats the processes of charging, exposing, developing, transferring, and fixing the input image signal from the buffer memory 7 to continuously print the size-specified sheet. And record.

FIG. 2 is a block diagram showing the function of the sensor drive circuit 5 in FIG. 1, and FIG. 3 is an operation timing chart diagram of the sensor drive circuit 5. In FIG. 2, an oscillator 501 generates a pixel clock SCLK having a constant period,
The pixel counter 503 counts the pixel clock SCLK and outputs the count address value Add. The CPU 110 of the controller 11 sets the number of periodic pixels Bx that determines the pulse period of the transfer pulse SH in the first comparator 504 via the I / O port 502, and sets the number of effective pixels Cx of the image information in the second comparator 505. To set. The first comparator 504 compares the count address value Add of the pixel counter 503 with the set number of pixels Bx, and outputs a transfer pulse SH to “H” when Add = Bx. The pixel counter 503 clears the count address value Add to 0 when the transfer pulse SH falls. The second comparator 505 compares the count address value Add with the number of effective pixels Cx, and 0 ≦ Ad
"L" signal when d≤Cx, "H" when Cx <Add
The image valid signal SEN of the signal is output. As shown in FIG. 3, if the period of the pixel clock SCLK is tc (s), the number of periodic pixels is Bx, and the number of effective pixels is Cx, the transfer pulse S
The period ti (s) of H and the effective image information time tg (s) are calculated based on (Equation 1) and (Equation 2), respectively.

[0036]

[Equation 1]

[0037]

[Equation 2]

As a result, the CPU 11 of the controller 11
0 is set to a desired value for the number of periodic pixels Bx and the number of effective pixels Cx, so that the period ti of the transfer pulse SH and the effective image signal S
The time tg of EN can be changed. When the number of periodic pixels Bx is set, when the set value Bx is set in the latch 507, the set value Bx is output to the first comparator 504 by the latch 506 at the fall of the transfer pulse SH.

By the way, the period ti of the transfer pulse SH is the accumulation time of the optical signal of the line sensor 1. Therefore, in order to keep the reading resolution in the sub-scanning direction constant, it is necessary to change the period ti according to the document reading scanning speed of the line sensor 1. When the reading scanning speed is Vx (mm / s) and the sub-scanning resolution is Y (dot / mm), the period ti is (Equation 3).
Need to be set based on.

[0040]

[Equation 3]

Therefore, the maximum value of the reading scanning speed is Vma
x (mm / s), the minimum value is Vmin (mm / s), and the sub-scanning resolution Y (dot / mm), the minimum value Tmin of the period ti and the maximum value Tmax of the period ti are (Equation 4) and (Equation 5). ) Is calculated based on.

[0042]

[Equation 4]

[0043]

[Equation 5]

Further, in order to output all the effective image information within the period of changing cycle ti, it is necessary to always satisfy tg <ti. When the minimum value of the period ti is Tmin and the number of effective pixels is Cx, the period tc of the pixel clock SCLK is set so as to satisfy (Equation 6).

[0045]

[Equation 6]

Further, in order to change the cycle ti of the transfer pulse SH to Tmax in the cycle tc satisfying (Equation 6), the pixel counter 503, the first comparator 504, and the second comparator 505 have [Tmax / tc. ] The address values Add up to +1 can be counted and compared.
Here, [] is an integerization process that rounds down the fractional part.

By configuring the sensor drive circuit 5 as described above, the cycle ti of the transfer pulse SH can be changed from Tmin to Tmax with the accuracy of the time tc. Therefore, the original reading scan of the line sensor 1 is set to the maximum value Vma.
In the range of the scanning speed from x (mm / s) to the minimum value Vmin (mm / s), the sub-scanning resolution is Y (dot / dot /
mm) and can be changed.

Maximum value of scanning speed Vmax (mm / s),
Minimum value Vmin (mm / s), sub-scanning resolution Y (dot)
/ Mm), the cycle tc (s), and the number of effective pixels Cx set by the copy document size are values determined by the design specifications of the apparatus, and the design values of Vmax, Vmin, Y, tc, and Cx are the controller 11 values. Read only memory 112
(Hereinafter simply referred to as ROM 112).

The transfer pulse SH generated by the sensor drive circuit 5 and the pixel clock SCL synchronized with the transfer pulse SH
The K and the image valid signal SEN are output to the line sensor 1, the controller 11, and the sampling circuit 19, respectively.
Although the cycle tc of the oscillator 501 is a fixed cycle in the above description, it is also possible to change the cycle ti by changing the cycle tc. In this case, a plurality of oscillators may be used, or the output cycle of one oscillator may be changed by setting.

FIG. 4 is a block diagram showing the function of the signal processing circuit 6 in FIG. 1, FIG. 5 is a relationship diagram between the digital signal output before white shading correction and the amplification amount of the analog signal amplifier, and FIG. 6 is the amplification amount correction. The flowchart figure is shown. The signal processing circuit 6 has three correction operations: amplification amount correction, white shading correction, and black shading correction. The correction operation is performed in the order of amplification amount correction, black shading correction, and white shading correction.

First, the amplification amount correction will be described. As shown in FIG. 5, when the cycle ti of the transfer pulse SH output to the line sensor 1 is changed from Tmax to Tmin, when the amplification amount of the analog amplifier 601 is fixed, the digital signal output is from point E to point F. Change. This is because the exposure amount to the line sensor 1 is constant, but by shortening the period ti of the transfer pulse SH, the accumulation time of the optical signal of the line sensor 1 becomes shorter, and as a result, the output signal of the line sensor 1 becomes smaller. Because it has become. When the output value of the analog amplifier 601 becomes small, there arises a problem of distortion when the analog image signal is quantized into a digital signal by the A / D converter 603. Therefore, as the period ti becomes shorter, the amplification amount of the analog amplifier 601 is increased and changed from the point B to the point C, and the input signal of the A / D converter 603 is corrected to the reference value or more. As a result, the digital signal output changes from point E to point G. This amplification amount correction operation causes a cycle ti
It is possible to quantize the analog signal with high accuracy even when is changed. As for the correction value of the amplification amount, a correction expression is obtained from the amplification values at the points B and C, and the amplification value corresponding to the cycle ti can be obtained by performing interpolation calculation processing.

The amplification amount correction operation will be described below with reference to the flowchart of FIG. (1) In the amplification amount correction operation, the motor control circuit 10 drives and controls the motor 8a in accordance with the control signal from the controller 11, moves the line sensor 1 to the position P1 of the reference white plate 16 for shading correction, and stops it. Also,
The light source 3 is turned on. (Step S1) (2) The controller 11 sets the cycle ti of the transfer pulse SH to Tmax as an initial setting. The CPU 110 inside the controller reads the cycle tc from the ROM 112 and calculates the cycle pixel number Bx that is Tmax from (Equation 1). By setting Bx in the latch 507, the cycle t
i is set to Tmax. Also, I / O port 609
The initial amount of amplification (point A) is set in the latch 607 via, and the coefficient K = 0 is set in the latch 614. Latch 6
The data of 07 is output to the D / A converter 602 at the fall of the transfer pulse SH by the latch 608, and the latch 6
The data of 14 is output to the multiplier 612 by the latch 613 at the fall of the transfer pulse SH. Therefore, the output of the multiplier 612 becomes 0, the output of the random access memory circuit 610 (hereinafter simply referred to as the RAM 610) is not added by the adder 611, and the output of the A / D converter 603 is directly input to the multiplier circuit 605. It becomes a value. Amplifier 601
Is a voltage-controlled variable amplifier that changes the amplification amount according to the potential output from the D / A converter 602. (Step S2) (3) After the initialization is completed, the analog image signal output from the line sensor 1 is amplified by the amplifier 601, and further the analog signal is converted to 00 by the 8-bit A / D converter 603.
(HEX) is converted to a digital signal of FF (HEX). In response to a control signal from the controller 11 via the I / O port 609, the image data for one line scan is temporarily transferred to the random access memory circuit 604 (hereinafter simply referred to as RA
It is called M604. ) To remember. The RAM 604 has a capacity capable of storing image data for one line scan and a main scan pixel counter. (Step S3) (4) The image data for one line scan stored in the RAM 604 is read in pixel units by a control signal from the CPU 110 of the controller 11 via the I / O port 609, and the read data are sequentially read. Compared.
Maximum value Dmax (point D) of image data by comparison processing
Is detected and the address (MAX_ADD) of the RAM 604 storing the maximum value is stored in the internal RAM 111 of the controller 11. (Step S4) (5) The controller 11 causes the output value Dmax (point D) of the A / D converter 603 to be in a reference range, that is, DL ≦ Dma.
The set value of the latch 607 is increased or decreased until x <DH.
DL and DH are values obtained experimentally. The reference image data output from the A / D converter 603 is the address (M) of the RAM 604 stored in the internal RAM 111 in step S4.
Image data stored in (AX_ADD). A
The set value (Amin) of the amplification amount B point when the output D point of the / D converter 603 becomes the E point in the reference range is stored in the internal RAM 111 of the controller 11. Controller 11
The CPU 110 executes interrupt processing at the falling edge of the transfer pulse SH, and latches 60 during this interrupt processing.
The data value of the amplification amount is set to 7. After setting the data,
A control signal for storing image data for one line scan in the RAM 604 is output. R image data for one line scan
One cycle of the cycle ti of the transfer pulse SH is required to store in the AM 604, and the CPU 110 reads the reference image data in the second interrupt cycle after the data setting is completed. The processing of this interrupt processing routine ends when the output (point D) of the A / D converter 603 reaches point E in the reference range. (Step S5) (6) The controller 11 sets the cycle ti of the transfer pulse SH to Tmin. The CPU 110 reads the cycle tc from the ROM 112 and calculates the cycle pixel number Bx that is Tmin from (Equation 1). By setting Bx in the latch 507, the cycle ti is set to Tmin. Further, the set value of the latch 607 is increased or decreased until the output value Dmax (point F) of the A / D converter 603 becomes the reference range, that is, DL ≦ Dmax <DH. DL and DH are values obtained experimentally. The reference image data output from the A / D converter 603 is the RAM stored in the internal RAM 111 in step S4.
The image data is stored at the address 604 (MAX_ADD). Output of A / D converter 603 (point F)
The set value (Amax) of the amplification amount C point when is the reference point G point is stored in the internal RAM 111 of the controller 11. The data setting of the amplification amount and the reading of the reference image data are performed in the same manner as (step S5). (Step S
6) (7) Internal RA in (step S5) and (step S6)
From the amplification values Amax and Amin stored in M111, C
The PU 110 obtains a correction formula for calculating the amplification value Again corresponding to the change in the period ti of the transfer pulse SH. The correction formula is shown in (Equation 7). (Step S7)

[0053]

[Equation 7]

The amplification value Aga when the period ti changes from Tmin to Tmax by the above amplification amount correction operation
The correction formula (Equation 7) for calculating in is derived, and the controller 1
The correction formula (Equation 7) is stored in the internal RAM 111 of No. 1. During the scanning of reading the original, the period ti is set, that is, the number of periodic pixels Bx
Is set in the latch 507, the amplification value Again is interpolated based on the correction formula (Equation 7), and the amplification value Agai is calculated.
The operation of setting n in the latch 607 is performed.

By this operation, the analog signal can be quantized accurately even if the period ti changes from Tmin to Tmax. Next, the black shading correction will be described. The black shading correction operation is performed after the amplification amount correction operation is completed. The controller 11 turns off the light source 3 and sets the cycle ti of the transfer pulse SH to Tmax. The CPU 110 reads the cycle tc from the ROM 112 and calculates the cycle pixel number Bx that is Tmax from (Equation 1). By setting Bx in the latch 507, the cycle t
i is set to Tmax. Further, the amplification value Amin stored in the RAM 111 is set in the latch 607 via the I / O port 609. The data in the latch 607 is output to the D / A converter 602 at the falling edge of the transfer pulse SH by the latch 608.

An analog image signal output from the line sensor 1 is amplified by an amplifier 601 and further an 8-bit A /
The D converter 603 converts the analog signal from 00 (HEX) to FF (HEX) digital signal. Image data for one line scan is transferred to the RAM 610 by a control signal from the controller 11 via the I / O port 609.
Remember. Further, the CPU 110 of the controller 11 causes the temperature detection sensor 20 to detect the temperature TBs during black level correction.
Input (° C.) and save it in the RAM 111.

As a result, the RAM 610 stores the correction value data Dk (i) of the read black level for each pixel when the light source 3 is turned off. Accordingly, the latch 614 now has a coefficient K
Is set. The data in the latch 614 is output to the multiplier 612 at the fall of the transfer pulse SH by the latch 613, and the black level correction value of the RAM 610 is the multiplier 61.
It is multiplied by K in 2 and output to the adder 611.

At the time of reading the original, the correction value data K × Dk of the black level multiplied by K from the image data D (i) obtained by reading and scanning the original 13 (the output data of the A / D converter 603).
An operation to reduce (i), that is, the output Dout = D (i) -K
Perform × Dk (i). (Black level correction) When the period ti changes, the CPU 1 of the controller 11
10 is the coefficient K corresponding to the amplification value Again K = Aga
Correct to in / Amin. Cycle t during scanning
After the setting of i, the amplification value Again is calculated based on the correction equation (Equation 7), the coefficient K is calculated from K = Again / Amin, and the coefficient K is set in the latch 614.

By this operation, the cycle ti changes from Tmin to Tmax, and the amplification amount is correspondingly changed to Ami.
Even if the value is changed from n to Amax, the black level can be accurately corrected. By the way, the black level distortion is mainly due to the dark current generated in the photodiode, the storage electrode and the CCD shift register. Dark current is greatly affected by temperature. Therefore, the CPU 110 of the controller 11
Is TBs (° C.) when the black level is stored in the RAM 111, and TBst (° C.) is the temperature detected by the controller 11 from the temperature detection sensor 20.
TBst and TBs are compared, and if TBst> TBs is established, the temperature change rate is α (times / ° C.) and Kx = α × (TB
The coefficient Kx is calculated from st-TBs) × K, and the latch 61
The correction control of the coefficient K which sets the coefficient Kx to 4 is performed. α
Is a value obtained experimentally, and is stored in the ROM 112.

By setting the coefficient Kx by the correction control of the coefficient K, the light shielding position P can be set even during the movement for performing the black level correction operation when the temperature changes, that is, during the continuous reading scanning.
It is not necessary to move the line sensor 1 to 1, and continuous reading scanning can be performed at high speed. Further, the black level can be accurately corrected even if the entire temperature of the line sensor 1 changes.

Next, the white shading correction operation will be described. The white shading correction operation is performed after the amplification amount correction operation and the black shading correction operation are completed. The controller 11 turns on the light source 3 and sets the cycle ti of the transfer pulse SH to Tmax. The CPU 110 reads the cycle tc from the ROM 112, and calculates Tm from (Equation 1).
The number of periodic pixels Bx that is ax is calculated. By setting Bx in the latch 507, the cycle ti is set to Tmax. Further, the amplified value Amin stored in the RAM 111 is read out, and the A value is stored in the latch 607 via the I / O port 609.
min is set, and the coefficient K = 1 is set in the latch 614. The data of the latch 607 is output by the latch 608 to the D / A converter 602 at the falling edge of the transfer pulse SH, and the data of the latch 614 is output by the latch 613 to the multiplier 612 at the falling edge of the transfer pulse SH.
By setting the coefficient K = 1 in the latch 614, the output of the multiplier 612 becomes the same as the output of the RAM 610.
The adder 611 subtracts the output of the multiplier 612 from the output of the A / D converter 603 and outputs it to the multiplication circuit 605. An analog image signal output from the line sensor 1 is amplified by an amplifier 601 and further an 8-bit A / D converter 603.
The analog signal from 00 (HEX) to FF (HE
X) digital signal. 1 by a control signal from the controller 11 via the I / O port 609
Image data for line scanning is temporarily stored in the RAM 604. The CPU 110 of the controller 11 reads the pixel data stored in the RAM 604 via the I / O port 609 on a pixel-by-pixel basis, calculates the reciprocal of the data, and writes it to the same address again. This operation is performed on pixels of all image data for one line scanning.

As a result, the RAM 604 stores the correction value data 1 / Dw (i) for each pixel when the reference white plate 16 is read.
Is memorized. At the time of reading the original, the image data D (i) obtained by reading and scanning the original 13 (the output data of the adder 611) and the correction value 1 / Dw stored in the RAM 604.
Output from (i) Dout (HEX) = D (i) × FF
(HEX) / Dw (i) is calculated in the multiplication circuit 607. (White Level Correction) By the above signal correction operation, it is possible to correct the light amount unevenness of the light source 3 and the sensitivity unevenness of each light receiving element of the line sensor 1. The density conversion circuit 608 converts the reflectance linear image signal output from the multiplication circuit 607 into a density linear image signal and outputs the image signal. When the white shading correction operation is completed, the motor control circuit 10 drives and controls the motor 8a according to the control signal from the controller 11, and the line sensor 1
Is moved from the position P1 of the reference white plate 16 to the document reading start position and stopped. Further, the controller 11 turns off the light source 3.

An embodiment in the case where the image reading apparatus of the present invention performs the same-magnification reading scan will be described with reference to FIGS. FIG. 7 is a timing chart for correcting the reading scanning speed. The speed detection circuit 18 (see FIG. 1) counts the cycle of the encoder pulse output from the sensor 8b with the internal clock to obtain the speed signal V of digital value.
To generate. Then, the sampling circuit 19 samples the speed signal V at the rising edge of the transfer pulse SH. As shown in FIG. 7, the CPU 110 of the controller 11 performs steps S71 and S at the fall of the transfer pulse SH.
72, the interrupt process of step S73 is executed. The contents of interrupt processing will be described.

(Step S71) C of the controller 11
The PU 110 reads the speed signal Vs of the sampling circuit 19 and calculates the optimum cycle ti from the speed signal Vs based on (Equation 3). When the read speed is Vs (mm / s) and the sub-scanning resolution of the image reading device is Y (dot / mm), the period ti is as shown in (Equation 8).

[0065]

[Equation 8]

Next, the CPU 110 reads the maximum value Vmax, the minimum value Vmin, and the sub-scanning resolution Y from the ROM 112, and calculates Tmin and Tmax based on (Equation 4) and (Equation 5). After the calculation is completed, it is determined whether the period ti obtained by (Equation 8) satisfies the condition of Tmin ≦ ti ≦ Tmax. If the condition is satisfied, the cycle ti is stored in the RAM 11
1 is stored, and (step S72) is processed. If the condition is not satisfied, the interrupt process ends.

(Step S72) CPU 110 is ROM
The period tc from 112 and the period ti from the RAM 111 are read out, the number of periodic pixels Bx is calculated based on (Equation 9), and RA
Save to M111. Here, [] is an integerization process that rounds down the fractional part.

[0068]

[Equation 9]

Next, based on (Equation 7), the amplification amount Agai
n is calculated, the set amplification value Ax obtained by integer processing is calculated, and R
Save in AM111. Further, the CPU 110 newly detects the output of the temperature detection sensor 20 via the I / O port 113, and detects the detected temperature TBst (° C.) and the RAM 11
The temperature TBs (° C.) stored in 1 at the time of black level correction is compared. If TBst ≦ TBs, then K = Again / A
min is calculated, the coefficient Kst is set to K, and the coefficient Kst is set to R.
Save in AM111. If TBst> TBs, the temperature change rate is α (times / ° C.) and Kx = α × (TBst−T
The coefficient Kx is calculated from Bs) × K, and the coefficient Kst is stored in the RAM 111 with the coefficient Kst = Kx. α is a value obtained experimentally and stored in the ROM 112.

(Step S73) The number of periodic pixels Bx stored in the RAM 111 in (Step S72) is set in the latch 507 of the sensor drive circuit 5, the amplification value Ax is set in the latch 607 of the signal processing circuit 6, and the coefficient Kst is set. Set in latch 614. At the falling edge of the transfer pulse SH, the amplified value Ax passes through the latch 608 to D /
The A converter 602 is set, and the amplification amount of the amplifier 601 is set. Further, the number of periodic pixels Bx at the fall of the transfer pulse SH is passed through the latch 506 and the first comparison circuit 504.
And the period ti is set. Further, at the fall of the transfer pulse SH, the coefficient Kst is set in the multiplier 612 via the latch 613, and the black level correction value of the RAM 610 is multiplied by Kst in the multiplier 612 and output to the adder 611. .. The adder 611 subtracts the output of the multiplier 612 from the image data.

By executing the above interrupt processing, the cycle ti corresponding to the reading scanning speed of the image reading apparatus, the amplification amount Gain and the coefficient Kst can be set with a delay of one cycle at the cycle of the transfer pulse SH. As a result, the original 13 can be read at a constant resolution Y (dot / mm) even if the reading scanning speed of the image reading device changes, the analog signal is quantized more accurately, and the black level is corrected more accurately. can do.

FIG. 8 is an explanatory view of the velocity profile and correction of the same-magnification reading scan. In FIG. 8, the acceleration scanning time is from t0 to t2, and the velocity Va (mm is from t2 to t3.
/ S) is a constant speed scanning time, and t3 to t5 is a deceleration scanning time. From t5 to t6, the line sensor 1 returns from the document end position P3 to the start position before the document start position P2, and the maximum return speed is -Vb.
(Mm / s). The first original reading scan is completed in a time period from t0 to t6. From t6 to t8 is the second accelerated scanning time, and thereafter, scanning is performed with the same velocity profile as t2 to t6. In the document scanning area (step S71), the image reading device (step S7)
2) By executing the interrupt process of (step S73), the document reading scanning speed V becomes Vmin (mm / mm /
After time t1 when s) is reached, the velocity sampling value Vs
According to (mm / s), the correction of the period ti of the transfer pulse SH, the amplification amount, and the correction of the black level, that is, the number of periodic pixels Bx, the amplification value Ax, and the coefficient Kst are set. Number of pixels B
The setting of x, the amplification value Ax, and the coefficient Kst is repeatedly performed until the time t4 when the document reading speed V again becomes Vmin (mm / s) in the deceleration scanning area.

As a result, the document 13 can be scanned at a constant resolution Y (dot / mm) from t1 to t4, the analog signal can be quantized with higher accuracy, and the black level can be corrected with higher accuracy. Compared with the conventional image reading apparatus which performs the reading scanning of the document 13 only within the range of the constant speed Va (mm / s) of the constant speed scanning time tq, the image reading apparatus of the present invention has an accelerated scanning time tp from t1 to t2. , And the deceleration scanning time tr from t3 to t4 can be read and scanned, and when read scanning is repeatedly performed, tp,
It is possible to shorten the time tx for the reading scan within the time of tr. Resolution Y (dot / mm), constant speed Va (mm /
s), when the minimum value Vmin (mm / s) of the reading scanning speed is set, the time tx calculated in (Equation 10) can be shortened.

[0074]

[Equation 10]

Explaining up to t8 which is the second scanning, the time tx is shortened by using the time from t3 to t4 and the time from t7 to t8 in the time from t3 to t8 as the reading time. be able to. As a result, when the reciprocal reciprocal reading operation is performed, the time tx can be shortened by one reading scanning time, and an image reading device that performs high speed reciprocal reading operation can be realized.

In the image reading apparatus of the present invention using the buffer memory 7, an embodiment of the copying operation when connected to an output device for recording by raster scanning at a constant speed Va (mm / s) is shown in FIGS. It will be explained using. FIG. 9 is an explanatory diagram of the operation of the buffer memory 7. In FIG. 9, I /
In response to a control signal from the controller 11 via the O port 703, the memory control circuit 702 sequentially stores the input image data in the memory 701 in units of one scanning line. Further, the stored image data is sequentially output in units of one line scan in order from the input image data. The memory 701 is a dual-port first-in / first-out memory (hereinafter simply referred to as FIF) in which writing and reading can be performed in duplicate to perform the above-described input / output operations.
It is called O memory. ) Is a configuration buffer. The number of image data sequentially stored in the memory 701 in one scanning line is determined by the memory control circuit 702.
If Nx is an “L” section, that is, the number of effective pixels set in the second comparator 505 of the sensor drive circuit 5 is Cx, then Cx + 1
It becomes the number of pixels of. The number of effective pixels Cx is determined by the copy document selection unit 17
It is determined by the copy document size set from Of the copy document sizes, the size in the main scanning direction is Sx (m
m) and the main scanning resolution is X (dot / mm), C
The PU 110 calculates Cx = [X × Sx−1] and sets it in the second comparator 505. Here, [] is an integerization process that rounds down the fractional part.

The acceleration region tp and the deceleration region t shown in FIG.
Of the time to read r, if tp ≧ tr, then tm = tp,
When tp <tr, tm = tr is set, and the controller 11
Sequentially stores the image data of the number of scanning lines read and scanned in the time tm in the buffer memory 7. Resolution Y
(Dot / mm), constant speed Va (mm / s), and minimum reading scanning speed Vmin (mm / s), tm
The number of scanning lines Lx corresponding to the time of (s) is (equation 1
Calculated based on 1). Here, [] is an integerization process that rounds down the fractional part.

[0078]

[Equation 11]

If the output device is the printer 14, for example,
The controller 11 stores the image data up to the number of scanning lines Lx in the buffer memory 7 in synchronization with VSYNC from the printer 14, and then sequentially stores the image data sequentially stored from the scanning line (1) in the HSYNC and PCLK of the printer 14.
The output is performed in synchronism with. Since the reading scanning speed and the writing scanning speed are Va (mm / s), the number of scanning lines stored in the acceleration / deceleration area from t1 to t2 and t3 to t4 shown in FIG. 8 is in the range from 1 to Lx. It changes with. Further, when the reading scanning is repeatedly performed, the reading scanning within the time of tp and tr, that is, the time tx calculated in (Equation 10) can be shortened.

As in the above operation, the image data in the acceleration region is sequentially stored in the buffer memory 7 and is sequentially output in the constant velocity or deceleration region to obtain a constant velocity Va (mm /
It is possible to connect a device for recording by raster scanning in (s).
Further, in the embodiment of the image reading apparatus of the present invention, the time can be shortened by the time tx (s) for each reciprocal reading operation, which is faster than the conventional image reading apparatus which reads only the constant speed Va (mm / s) section. Continuous reading and reciprocating operation is possible.

As a result, when the copying operation is executed by using the image reading device, the high-speed continuous copying operation can be performed with the small capacity memory. Next, an embodiment of the image copying apparatus will be described with reference to FIGS. 9, 10 and 11. Figure 1
0 is a timing chart of the copying operation, and FIG. 11 is an explanatory diagram of the size of the copied document.

Referring to FIG. 10, an embodiment in the case of performing the same size copying will be described. T6 is VS of the printer 14
The time from the fall of YNC to the start of the recording scan at the leading end position of the recording sheet, T1 is the repeating time for the printer 14 to perform sub-scan recording on the recording sheet, and T2 is the line sensor 1.
Is the time for reading and scanning from the start end position to the end position of the document 13, T3 is the time for the line sensor 1 to return from the end position of the document 13 to the start position, and T4 is the image data from the front end position to the end position of the recording paper by the printer 14. Sub-scanning recording time, T5 is time T2 when the line sensor 1 reads and scans from the starting position to the ending position of the document 13 and the printer 14.
Is the difference from the time T4 during which the sub-scanning of the image data is recorded on the recording paper, that is, T4−T2 = T5 (T2 <T4).
Further, the line sensor 1 does not perform operations such as acceleration / deceleration scanning, stop, and restart during the image reading scanning. That is, the scanning speed is controlled to be constant.

Since the image reading / scanning speed is set higher than the image recording / scanning speed, the image data is sequentially stored in the buffer memory 7, and the maximum stored image data amount is the time when the image reading of the original 13 is completed. That is, of the amount of scanned image data read from the line sensor 1, the amount of image data not yet scanned and recorded in the printer 14 is sequentially stored in the buffer memory 7. The storage capacity Mmax of the image data required when the acceleration / deceleration area of the image reading scan is not stored in the buffer memory 7 is calculated based on (Equation 12), and the maximum number of image scanning lines Lm stored in the buffer memory 7 is ( It is calculated based on the equation 13). Main scanning resolution X (dot / mm), sub-scanning resolution Y (dot / mm), main scanning size Sx of read document
(Mm), the sub-scanning size Sy (mm), the image reading scanning time T2 (s), the image recording scanning time T4 (s), and the gradation number N (bit / pixel) of one pixel. X, Y, N, and Sx and Sy for each copy size are design values, and ROM
It is stored in 112. (However, Mp is a capacity for storing one page of the copy document.)

[0084]

[Equation 12]

[0085]

[Equation 13]

In the above embodiment, the acceleration / deceleration area of the image reading scan is not stored in the buffer memory 7. further,
The image reading scanning speed is faster than the image recording scanning speed. Therefore, the controller 11 is the VSYNC of the printer 14.
After the scanning image data of two or more lines are sequentially stored in the buffer memory 7 in synchronization with the trailing edge of, the image data sequentially stored from the scanning line (1) are sequentially output in synchronization with HSYNC and PCLK of the printer 14. Perform the operation. The printer 14 performs recording scanning from the position of the leading edge of the recording sheet. From the start to the end of the image reading scan, the buffer memory 7 successively stores image data from 1 to the maximum Lm (line), and after the reading scan is completed, the buffer memory 7 transfers the image data to the printer 14 at T5. Only image data will be output.

As an example of the storage capacity, T2 is 0.8 times T4.
If the time is set to double, the maximum amount of image data stored in the buffer memory 7 is calculated from (Equation 12), which is 0.2 compared with the storage capacity Mp for storing one page of original image data. The storage capacity is × Mp. On the other hand, the time required for the line sensor 1 to return from the end position to the start position can be lengthened by T5, and in this example, can be lengthened by the time of 0.2 × T4.

As shown in the above embodiment, the return time when the line sensor 1 is reciprocally driven, that is, the time required for the line sensor 1 to return from the terminal end position P3 to the starting end position P2 can be lengthened, and the heavy carriage unit 4 can be mounted. The load on the driving motor 8a is reduced. Further, the printer 14 needs to perform high-speed scanning recording similarly to the reading device in order to gain the return time of the reading scanning, but the scanning recording speed can be slowed by the time T5 as compared with the reading device. Therefore, according to the present embodiment, a high-speed reciprocating driving operation of the reading device can be realized, and further, the printer 14 for performing high-speed scanning recording is not necessary.

As a result, it is possible to easily realize an image copying apparatus which performs a high-speed copying operation with a small capacity memory. Further, since the time T3 can be set long, the document replacement time (T3 +
T6) is sufficiently secured, and it is possible to easily realize an image copying apparatus that not only copies one original at a high speed to a large number of sheets, but also makes a high speed copy of a plurality of originals to a large number of sheets. An embodiment in which a copy original is selected using the above image copying apparatus will be described with reference to FIGS.

FIG. 11 is an explanatory diagram of the size of the copy original.
In FIG. 11, (A) is a LETTER size sheet,
(B) illustrates an arrangement of LEGDER size sheets. The main indicates the main scanning direction and the sub indicates the sub scanning direction. A specific example (a) in which the image reading scanning speed is not changed depending on the copy original will be described.

Specific Example (a) The operation when the copy original is selected as LETTER (A) will be described. To explain, from time T1 to T in FIG.
Set a temporary value up to 6. For example, T1 = 1.5
(S), T2 = 0.8 (s), T3 = 0.6 (s), T
4 = 1.0 (s), T5 = 0.2 (s), T6 = 0.1
Set as (s). With the above settings, LETTER
It is possible to perform a copying operation of 40 sheets / minute with the copy original. The storage capacity of the buffer memory 7 is 0.2 × Mpa at maximum from (Equation 12). (However, Mpa is LETTER
This is the storage capacity for one page of the document. At this time, the image reading scanning speed is 216 ÷ 0.8 = 270 (mm / s), and the recording scanning speed is 216 ÷ 1 = 216 (mm / s).

Next, the image reading scanning speed 270 (mm /
s), a description will be given of the operation (B) in the case where the copy original is selected as the LEDGER with the recording scan speed 216 (mm / s). Set the numerical value when performing a copy operation of 20 sheets / minute for the copy document of LEDGER. T1 = 3.0 (s), T
2 = 1.6 (s), T3 = 1.3 (s), T4 = 2.0
(S), T5 = 0.4 (s), and T6 = 0.1 (s).

The storage capacity of the buffer memory 7 is (Equation 12).
Therefore, the maximum is 2 × 0.2 × Mpa = 0.4 × Mpa.
(However, Mpa is the storage capacity for one page of the LETTER original.) Here, the storage capacity is twice as large as that of the LETTER original because the original size in the sub-scanning direction is doubled. This is because the storage capacity for one page of the manuscript has been doubled.

As described in the above specific example (a), when the image reading scanning speed and the recording scanning speed are not changed depending on the copy original, the capacity stored in the buffer memory 7 differs depending on the copy original. In the example, LEDGE
R needs to store twice the capacity of LETTER.
Therefore, the controller 11 changes the image reading scanning speed according to the copy original selected by the copy original selecting unit 17 and performs an operation of reducing the storage capacity.

A specific example (b) in which the image reading scanning speed is changed according to the copy original will be described. Specific Example (b) When the copy original of the specific example (a) is selected for LEDGER (B), the set value is changed as follows. T1
= 3.0 (s), T2 = 1.8 (s), T3 = 1.1
(S), T4 = 2.0 (s), T5 = 0.2 (s), T
6 = 0.1 (s). With this setting, as in the case of the specific example (a), it is possible to perform a copy operation of 20 sheets / minute with the LEDGER copy original.

On the other hand, the storage capacity of the buffer memory 7 is maximum 2 × 0.1 × Mpa = 0.2 × Mpa from (Equation 12). (However, Mpa is the storage capacity for one page of the LETTER original.) At this time, the image reading scanning speed is 43.
2 ÷ 1.8 = 240 (mm / s), and the recording scanning speed becomes 216 (mm / s).

The storage capacity of the buffer memory 7 can be reduced by changing the image reading / scanning speed according to the copy original as in the specific example (b) above. When the copy original is LED GER, the return time of the line sensor 1 can use a high-speed scanning area as a ratio in return scanning as compared with LETTER, and T3 is set to 0.
The operation of shortening by 2 (s) can be easily realized.

T1, T4, T6, Mp and Mmax are values determined by design values for each copy original. Each T1, T
4, T6, Mp and Mmax are ROMs of the controller 11
It is stored in 112. The CPU 110 stores the ROM 1 in accordance with the copy original selected by the copy original selecting unit 17.
The design values T1, T4, T6, Mp and Mmax are read from 12 and T2 is obtained from the relational expression of (Equation 12). ROM
The design values Y, Sy, and tc are read from 112 and the calculated T2 is obtained.
From image scanning speed Vx = Sy / T2 (mm / s)
Is calculated, and the set pixel number Bx is calculated according to (Equation 8) and (Equation 9) with Vx = Vs. The set pixel number Bx is set in the latch 507 of the sensor drive circuit 5.

Further, from ROM 112, Vmax, V
min and Y are read, and Tma is calculated from (Equation 4) and (Equation 5).
x and Tmin are calculated, and Amin and A are calculated from the RAM 111.
max is read and the amplification value Ag is calculated based on the correction formula (Equation 7).
Calculate ain. The amplification value Again is set in the latch 607. Further, the CPU 110 calculates a coefficient K from the amplified value Again so that K = Again / Amin, and sets the coefficient K in the latch 614.

Further, the CPU 110 of the controller 11
Is TBs (° C.) when the black level is stored in the RAM 111, and TBst (° C.) is the temperature detected by the controller 11 from the temperature detection sensor 20.
TBst and TBs are compared, and if TBst> TBs is established, the temperature change rate is α (times / ° C.) and Kx = α × (TB
The coefficient Kx is calculated from st-TBs) × K, and the latch 61
The correction control of the coefficient K which sets the coefficient Kx to 4 is performed. α
Is a value obtained experimentally, and is stored in the ROM 112.

Even if the image reading scanning speed is changed by this setting, the resolution Y (dot / mm) in the sub-scanning direction can be made constant, the analog signal can be quantized with high precision, and the black level can be accurately obtained. Can be corrected. In the present embodiment, a monochromatic image reading device and a monochromatic image copying device have been described as examples, but the line sensor 1 is a three-color sensor of red, blue, and green, and the printer 14 is yellow, cyan, and magenta. ,
A color image reading apparatus and a color image copying apparatus can be easily realized by using a color printer that forms a color image using a black recording color.

In this case, a color image reading device can be easily realized by having the signal processing circuits of this embodiment in parallel for the three colors of red, blue and green, and further, the red, blue and green colors can be used. A color printer can be connected by performing image processing to generate recording colors of yellow, cyan, magenta, and black from color parallel signals. When the color printer forms a color image in a frame-sequential manner, a high-speed color image copying apparatus can be realized by repeating this embodiment, which is performed by one reciprocating operation, four times.

When the color printer forms color images in parallel, a high-speed color image copying apparatus can be realized by one reciprocating operation as in this embodiment.

[0104]

As described above, according to the present invention,
The sub-scanning means accelerates the image reading line sensor to a printing scanning speed higher than the printing scanning speed of the image data output machine, and the second control means writes the read data to the storing means by one line by the line sensor. Read out from the storage means in accordance with the recording scan speed of the image data output device.

Therefore, the storage means need only store the difference between the image data generated by scanning the original by the image reading line sensor and the image data sent to the output device, and a small capacity memory can be used. Moreover, since the reading start line and the end line when the image reading line sensor is sub-scanned by the first control means are controlled according to the sub-scanning speed of the image reading line sensor, the acceleration / deceleration section of the image reading line sensor is controlled. The image can be read also in. As a result, the image reading amount in one sub-scan can be increased, in other words, if the same amount of image data can be read in a short sub-scanning time, a large number of copies of one original can be made.
Further, there is an effect that continuous recording for a large number of copies of a large number of originals can be performed at high speed even if the image reading line sensor is repeatedly sub-scanned.

Further, by providing the timing control means, the generation interval of the timing signal of the timing generation means can be changed according to the scanning speed of the image reading line sensor, and as a result, the scanning speed of the image reading line sensor can be changed. Even if it changes, there is an effect that the reading and scanning can be performed with a constant sub-scanning resolution. Further, by providing the amplification control means, it is possible to change the amplification amount of the amplification means according to the generation interval of the timing signal by the timing generation means, and as a result, the generation of the timing signal by the timing generation means to the read line sensor. Even if the interval changes, the analog image signal before quantization is controlled to a predetermined level, and it is possible to quantize with high accuracy.

Further, by providing the correction control means, the correction value of the black level correction means can be changed according to the amplification amount of the amplification means. As a result, the image reading line sensor stored before the document reading scanning is stored. The error in the correction value of the black level signal caused by the change in the amplification amount of the amplification means can be eliminated, and it is not necessary to store the correction value again by resetting the amplification amount during the scanning of reading the original. is there.

Further, if the correction control means changes the correction value of the black level correction means in accordance with the amplification amount of the amplification means and the temperature change amount detected by the temperature detection means, the original reading scan It is possible to eliminate an error caused by a change in the amplification amount of the amplifying means and an error caused by a temperature change in the correction value of the black level signal of the image reading line sensor, which is stored before, and the amplification amount is reset during the scanning for reading the original. There is an effect that it becomes unnecessary to store the correction value again due to the setting and the temperature change.

[Brief description of drawings]

FIG. 1 is a block diagram of an image reading apparatus and an image copying apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a function of a sensor drive circuit 5 in FIG.

FIG. 3 is an operation timing chart of the sensor drive circuit 5.

4 is a block diagram showing functions of a signal processing circuit 6 in FIG.

FIG. 5 is a relationship diagram between a digital signal output before white shading correction and an amplification amount of an analog signal amplifier.

FIG. 6 is a flowchart of amplification amount correction.

FIG. 7 is a timing chart for correcting the reading scanning speed.

FIG. 8 is an explanatory diagram of a velocity profile and correction of a 1 × scanning scan.

FIG. 9 is an operation explanatory diagram of the buffer memory 7.

FIG. 10 is a timing chart of a copying operation.

FIG. 11 is an explanatory diagram of copy document size.

[Explanation of symbols]

 1 line sensor 5 sensor drive circuit 6 signal processing circuit 7 buffer memory 11 control unit 14 printer 16 reference white plate 17 copy document selection unit 18 speed detection circuit 19 sampling circuit 20 temperature detection sensor

Claims (34)

[Claims] 1. An image reading line sensor for reading an original one line at a time and converting it into digital image data, storage means for storing a read image of at least one line, and the image reading line sensor for recording scanning of an image data output device. A sub-scanning unit that controls acceleration to a recording scanning speed that is equal to or higher than the speed, and a reading start line and an end line of the image reading line sensor in the sub-scanning direction are the sub-scanning speed of the image reading line sensor. The first control means that can be controlled in relation to each other, and the image in the effective range of the image of one line read by the image reading line sensor are sequentially read at a constant time equal to or shorter than the minimum value of the reading cycle of one line. The storage means is controlled so that it is stored in the storage means, and one line at a time is sequentially output from the storage means in accordance with the recording scanning speed of the output machine. An image reading apparatus comprising: a second control unit for reading. 2. The image reading apparatus according to claim 1, wherein the output device is a printer, and the sub-scanning unit is capable of changing the sub-scanning speed of the image reading line sensor according to the document size. .. 3. The image reading apparatus further comprises a timing generating means for generating a timing signal for determining a cycle for the image reading line sensor to read one line, and a generation interval of the timing signal as a subordinate of the image reading line sensor. 3. The image reading apparatus according to claim 1, further comprising a timing control unit that changes according to the sub-scanning speed so that a constant resolution can be obtained even if the scanning speed changes. 4. The image reading device further includes speed detection means for detecting a sub-scanning speed of the image reading line sensor, and the timing signal generation interval is controlled according to the detection result. Image reader. 5. The first control means causes the image reading line sensor to start image reading when the timing signal generation interval is within a control range from a minimum value to a maximum value controlled by the timing control means. 4. The image reading apparatus according to claim 3, wherein the image reading apparatus is controlled so as to end the image reading when it is out of the control range. 6. The second control means only stores image data while the image reading line sensor is being accelerated in the sub-scanning direction, and the image reading line sensor is kept at a constant speed or decelerated in the sub-scanning direction. 6. The image reading device according to claim 5, wherein the image data can be read out after being scanned. 7. The storage means maximizes the difference between the read image data amount sequentially input from the image reading line sensor and the output image data amount sequentially read line by line from the storage device according to the recording scanning speed of the output machine. The image reading apparatus according to claim 6, wherein the amount of stored data is used. 8. The image reading device further comprises an amplifying means for amplifying an output image signal of the image reading line sensor, and an amplifying means for changing an amplification amount of the amplifying means according to an interval of generation of a timing signal by the timing generating means. The image reading apparatus according to claim 3, further comprising: control means. 9. The image reading device further comprises a black level correcting means for correcting a black level signal of the image reading line sensor, and a correction for changing a correction value of the black level correcting means in accordance with an amplification amount of the amplifying means. 9. The image reading device according to claim 8, further comprising: a control unit. 10. The image reading device further comprises a black level correction means for correcting the black level signal of the image reading device line sensor, the temperature at which the black level correction of the image reading line sensor is made, and the scanning of the original reading. A temperature detecting means for detecting a difference between the temperature of the black level correcting means, and a correction control means for changing the correction value of the black level correcting means according to the amplification amount of the amplifying means and the temperature change amount detected by the temperature detecting means, 9. The image reading device according to claim 8, further comprising: 11. An image reading line sensor for reading an original one line at a time and converting it into digital image data, a storage means capable of storing a read image of at least one line, and reading from the storage means for recording at a constant recording scanning speed. Recording means, sub-scanning means for accelerating and controlling the image reading line sensor to a recording scanning speed equal to or higher than the recording scanning speed of the recording means, and starting reading of the image reading line sensor in the sub-scanning direction. First control means capable of controlling the line and the end line in relation to the sub-scanning speed of the image reading line sensor, and the image of the effective range among the images of the one line read by the image reading line sensor While controlling to sequentially store in the storage means at a constant time equal to or shorter than the minimum value of the cycle, Image copying apparatus characterized by comprising a second control means to sequentially read from the storage means by one line in accordance with a recording scan speed of the recording means. 12. The image copying apparatus further includes a designation unit for designating a copy document size, and the sub-scanning unit changes the sub-scanning speed of the image reading line sensor according to the designated document size. The image copying device according to claim 11. 13. The image copying apparatus further comprises a timing generating means for generating a timing signal for determining a period for the image reading line sensor to read one line, and a generation interval of the timing signal as a sub-value of the image reading line sensor. 13. The image copying apparatus according to claim 11, further comprising: a timing control unit that changes according to the sub-scanning speed so that a constant resolution can be obtained even if the scanning speed changes. 14. The image copying apparatus further includes speed detection means for detecting a sub-scanning speed of the image reading line sensor, and the timing signal generation interval is controlled according to the detection result. Image copier. 15. The first control means causes the image reading line sensor to start image reading when the timing signal generation interval is within the control range from the minimum value to the maximum value controlled by the timing control means. 14. The image copying apparatus according to claim 13, wherein the image reading apparatus is controlled so as to end the image reading when it is out of the control range. 16. The second control means only stores image data while the image reading line sensor is being accelerated in the sub scanning direction, and the image reading line sensor is decelerated at a constant speed or decelerated in the sub scanning direction. 16. The image copying apparatus according to claim 15, wherein the image data can be read out after being scanned. 17. The storage means maximizes the difference between the read image data amount sequentially input from the image reading line sensor and the output image data amount sequentially read line by line from the storage means in accordance with the recording scanning speed of the recording means. The image copying apparatus according to claim 16, wherein the amount of stored data is used. 18. The image copying apparatus further includes an amplifying unit for amplifying an output image signal of the image reading line sensor, and an amplifying unit for changing an amplification amount of the amplifying unit according to a timing signal generation interval by the timing generating unit. The image copying apparatus according to claim 13, further comprising a control unit. 19. The image copying apparatus further comprises a black level correction means for correcting the black level signal of the image reading line sensor, and a correction for changing the correction value of the black level correction means according to the amplification amount of the amplification means. The image copying apparatus according to claim 18, further comprising: control means. 20. The image reading device further comprises a black level correcting means for correcting a black level signal of the image reading device line sensor, a temperature at the time of performing the black level correction of the image reading line sensor, and an original reading scan. Temperature detection means for detecting a difference between the temperature of the black level correction means, and a correction control means for changing the correction value of the black level correction means according to the amplification amount of the amplification means and the temperature change amount detected by the temperature detection means, The image copying apparatus according to claim 18, further comprising: 21. The image reading apparatus according to claim 3, wherein the timing generation means changes the generation interval of the timing signal in units of a cycle of a pixel clock for transferring read pixels of the image reading line sensor. 22. The image reading apparatus according to claim 21, wherein the period of the pixel clock is constant and does not change according to the scanning speed of the image reading line sensor. 23. The timing control means changes the generation interval of the timing signal by the timing generation means in units of one scanning line.
The image reading device according to claim 5, 8, 9 or 10. 24. The image reading apparatus according to claim 8, wherein the amplification control means changes the amplification amount of the amplification means in units of one scanning line. 25. The amplification control means calculates the amplification amount data by performing an interpolation operation from the maximum amplification amount data and the minimum amplification amount data set in the amplification means, and changes the generation interval of the timing signal by the timing generation means. 25. The image reading apparatus according to claim 24, wherein the amplification amount of the amplification means is correspondingly changed. 26. The image reading apparatus according to claim 9, wherein the correction control unit changes the correction value of the black level correction unit in units of one scanning line. 27. The image copying apparatus according to claim 13, wherein the timing generating means changes the generation interval of the timing signal in units of a pixel clock cycle for transferring the read pixels of the image reading line sensor. 28. The image copying apparatus according to claim 27, wherein the period of the pixel clock is constant and does not change according to the scanning speed of the image reading line sensor. 29. The timing control means changes the generation interval of the timing signal by the timing generation means in units of one scanning line.
The image copying apparatus described in 4, 15, 18, 19 and 20. 30. An image copying apparatus according to claim 18, wherein the amplification control means changes the amplification amount of the amplification means in units of one scanning line. 31. The amplification control means calculates the amplification amount data by performing an interpolation operation from the maximum amplification amount data and the minimum amplification amount data set in the amplification means, and changes the generation interval of the timing signal by the timing generation means. 31. The image copying apparatus according to claim 30, wherein the amplification amount of the amplification means is correspondingly changed. 32. An image copying apparatus according to claim 19, wherein the correction control means changes the correction value of the black level correction means in units of one scanning line. 33. The timing control means is one of the reading means.
19. The image copying apparatus according to claim 13, wherein the scanning speed is detected in units of scanning lines. 34. The timing control means is one of the reading means.
9. The image reading apparatus according to claim 3, wherein the scanning speed is detected for each scanning line.