JP2001045236A - Image reading device - Google Patents

Abstract

(57) [Problem] To reduce the deviation between the position of a stepping motor and the phase of a line cycle signal (LSYNC) of a CCD at the time of resuming reading, thereby reducing image distortion. In an image reading apparatus, when a buffer memory for storing image data in a document reading operation becomes nearly full, the reading operation is stopped, and the phase of the CCD line cycle signal at that time is held at that position. After that, when the memory buffer becomes empty and reading starts again,
The CCD line cycle signal is output to the image processing unit at the held phase, and the phase of the CCD line cycle signal is matched with the position by driving the stepping motor.

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 such as a color scanner which intermittently reads an original while reading the original fixedly.

[0002]

2. Description of the Related Art Conventionally, when image data is transferred from a scanner to a personal computer, the processing performance of the personal computer depends on the image data. When the buffer memory is almost full, the scanner stops reading, stops the stepping motor through-down, stops, and returns the carriage to a position where reading can be resumed again. The synchronization signal LSYNC (hereinafter, referred to as LSYNC) for one line in the main scanning direction is generated by the image processing unit and is not particularly synchronized with the stepping motor. At present, there is an increasing need for a device capable of reading a color image with high precision. Therefore, when intermittent return control is performed, when the reading is stopped and restarted by the stepping motor, the phase of the CCD line cycle signal at the time of the stop is restarted. LSYNC phase when reading is restarted is 1 at the maximum.
There is a possibility that the line cycle is shifted, and there is a possibility that distortion occurs in an image read with high accuracy.

[0003]

The conventional method is shown in FIG.
The stepping motor is driven by controlling the stepping motor control circuit incorporated in the PU. However, since the LSYNC is generated by image processing, the stepping motor and the LSYNC are asynchronous. In other words, when the reading operation is started and the buffer memory becomes nearly full (near full), the reading is stopped and the stepping motor is slewed up in the reverse direction.
Down through. When the buffer memory becomes empty and reading is restarted, the stepping motor is slewed up, and the stepping motor is controlled so as to maintain a constant speed from the position where the reading was stopped. As shown in FIG. Therefore, there is a problem that the read image is distorted at the position where the reading is resumed. SUMMARY OF THE INVENTION It is an object of the present invention to provide an image reading apparatus that reduces a deviation of an LSYNC in which a stepping motor and an LSYNC are synchronized even when reading is stopped and restarted, thereby reducing distortion of a read image.

The object of the invention of claim 2 is that the stepping motor is stopped and returned after the buffer memory becomes full in claim 1 and reading is started at a position where the speed becomes constant again. In the case of a motor, mechanical vibrations cause mechanical vibrations on read images when reading is immediately resumed at a constant speed. An object of the present invention is to provide an image reading apparatus that reduces mechanical vibration during image reading and reduces distortion of a read image.

A third object of the present invention is to provide an image processing apparatus, comprising the steps of:
Since no SYNC is output, no clock is input to the CCD line sensor, so that the CCD line sensor saturates and adversely affects the read image when reading is resumed. SUMMARY OF THE INVENTION It is an object of the present invention to provide an image reading apparatus which can correct the saturation of a CCD line sensor even when reading is stopped.

[0006]

According to the first aspect of the present invention, a CC
The image reading is performed by the main scanning for reading the image data line by line from the D line sensor and the sub scanning by the driving of the stepping motor, and when the buffer memory for storing the image data in the original reading operation becomes almost full, the reading operation is stopped. Means for outputting a CCD line cycle signal to the image processing unit, a counter for counting the CCD line cycle signal, means for controlling count inhibition and permission in an image reading apparatus which starts reading again when the memory buffer becomes empty. When the buffer memory becomes almost full, the counter is inhibited from counting at the stopped position, the phase of the CCD line cycle signal at that time is held, and counting is started at the position where reading is started again. Drives the phase of the CCD line cycle signal and the stepping motor The combined by position, an image reading apparatus, characterized in that to reduce the distortion of the image.

According to a second aspect of the present invention, in the image reading apparatus according to the first aspect, the counter is a counter with a built-in CPU, and the counter is controlled by software to inhibit counting and permit counting. An image reading device.

According to a third aspect of the present invention, in the image reading apparatus according to the first aspect, when the buffer memory becomes nearly full, the reading operation is stopped and returned in the sub-scanning direction. The image reading apparatus is characterized in that when it becomes empty, it advances in the sub-scanning direction by the amount returned in the sub-scanning direction and resumes image reading.

According to a fourth aspect of the present invention, in the image reading apparatus according to the third aspect, the distance returned in the sub-scanning direction is such that the image reading can be resumed by proceeding a little after reaching a constant speed when reading is resumed, An image reading apparatus characterized in that reading is restarted after reducing the influence of mechanical vibration and distortion of a read image is reduced.

According to a fifth aspect of the present invention, there is provided the image reading apparatus according to any one of the first to fourth aspects, further comprising means for generating a pseudo CCD line cycle signal when reading is not performed, The image reading apparatus outputs a line cycle signal to a CCD line sensor and does not saturate the CCD even when reading is not performed.

According to a sixth aspect of the present invention, there is provided an image processing apparatus including the image reading device according to any one of the first to fifth aspects.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to embodiments. Hereinafter, the configuration operation of the present invention will be described. Figure 1
1 is an overall configuration diagram of an image reading device according to the present invention. The original placed on the platen glass 1 is illuminated by an illumination lamp 3 integrated with the first mirror 2, and its reflected light is
The first mirror 2 and the second mirror 4 and the third
Scanning is performed by the mirror 5. Thereafter, the reflected light is converged by the lens 31 and is irradiated on the CCD 6 to be photoelectrically converted. The first mirror 2, the illumination lamp 3, the second mirror 4, and the third mirror 5 are movable in the direction A by using the traveling body motor 7 as a drive source. Documents stacked on the document tray 8 are picked up by a pickup roller 9 and a registration roller pair 1.
The sheet is fed to the pair of transport rollers 13 and the pair of paper discharge rollers 14 via the reading position B by the transport drum 11 and the transport rollers 12, and is discharged onto the paper discharge tray 32.

When the document passes through the reading position B, the original is illuminated by the illumination lamp 3 moved near the reading position B, and its reflected light is reflected by the first mirror 2 and the second mirror 4 integrally formed. Are scanned by the third mirror 5. Thereafter, the reflected light is converged by the lens 31 and is irradiated on the CCD 6 to be photoelectrically converted. The pickup roller 9 and the registration roller pair 10 are driven by a feed motor (not shown), and the transport drum 11, the transport roller 12, the transport roller pair 13, and the discharge roller pair 14 are driven by a transport motor (not shown). Driven. At the reading position C, a contact image sensor 15 is provided. The contact image sensor 15 includes an LED (not shown) as a light source, a lens (not shown), and a sensor element (not shown).

When the document passes through the reading position C, the opposite surface (back surface) read at the reading position B is irradiated by the lamp in the contact image sensor 15 installed at the reading position C, and the reflected light Are focused by the upper lens of the contact image sensor 15, are irradiated to the sensor element on the contact image sensor 15, and are photoelectrically converted. A white roller 17 is provided on the opposite portion of the contact image sensor 15 that sandwiches the original.
Is used as a white member for shading correction at the time of reading by the close contact image sensor 15. An endorser unit 18 and an endorser platen 19 are provided between the transport roller pair 13 and the paper discharge roller pair 14. The endorser 18 has a printing section consisting of alphabetic letters and numerals marked with ink,
The printing unit includes a pressure solenoid (not shown) that presses the printing unit in the direction of the endor platen. The original is stopped on the endorser 18, fixed in the pressing direction by an endor platen 19, and alphabet characters and numerals can be printed on the original surface by applying pressure to the printing part of the endorser 18.

FIG. 2 is an overall block diagram of the image reading apparatus according to the present invention. The reflected light of the document that has entered the CCD 6 on the SBU 20 is converted into an analog signal having a voltage value corresponding to the light intensity in the CCD 6. The analog signal is
The output is divided into odd and even bits. In the analog image signal, a dark potential portion is removed by an analog processing circuit (not shown) on an SBU (Sensor Board Unit) 20, an odd bit and an even bit are combined, and the gain is adjusted to a predetermined amplitude. A after
The signal is input to a / D converter and converted into a digital signal. The digitized image signal is transmitted by SCU (Scanner Control Un
it: NIPU (N Im) on the scanner control unit 21
In the age processor unit (image processing chip) 33, shading correction, gamma correction, MTF correction, and the like are performed, and then binarized, and output as a video signal together with a page synchronization signal, a line synchronization signal, and an image clock. NI
The video signal output from the PU 33 is output to the option IPU 26 via the connector 34. Optional IPU (Image Prosessor Unit: Image processing chip)
The video signal output to the optional IPU 26
The predetermined image processing is performed in the SCU (Scanner
Control unit (scanner control unit) 21. The video signal input to the SCU 21 again is input to a selector (not shown). The other input of the selector is a video signal output from the NIPU 33, and the option IPU 26 can select whether or not to perform image processing. The video signal output from the selector is stored in an image data storage unit (DRA).
M) to manage SIBC (Scanner Image Buffer Contr)
ol: input to a scanner image memory buffer controller 35 and stored in an image memory composed of a DRAM. The image data stored in the image memory is sent to the SCSI controller 36 and transferred to an external device such as a personal computer.

The analog image signal photoelectrically converted by the contact image sensor 15 is converted to an RSBU (Reverce Sensor Boa).
(rd Unit: back side sensor board unit) 16 is converted into digital data. The digitized image signal is RS
After shading correction is performed on the BU, the RCU
(Reverse Control Unit: backside scanner control unit) 23. The RCU 23 has an image memory composed of DRAM and an SIBC for controlling the image data memory.
The image data is temporarily stored in the image memory and then transferred to the SCU 21. Image data sent from the RCU 23 to the SCU 21 and image data output from the SIBC 35 on the SCU 21 can be switched.
One of the image data is selected and transferred to the SCSI controller 36. CPU 37, R on SCU 21
An OM 38 and a RAM 39 are mounted, and the CPU 37
Controls the SCSI controller 36 to communicate with an external device such as a personal computer. Further, the CPU 37 also controls the timing of the traveling body motor 7, which is a stepping motor, the sheet feeding motor, and the transport motor. A
DU (Auto Document Unit: ADF control unit) 3
Reference numeral 0 has a function of relaying power supply of electrical components used in an automatic document feeder (ADF) unit. C on SCU21
The input port connected to the PU 37 is IOB (I /
O Bord (input / output board) 24 is connected to the main body operation panel 28. A start switch (not shown) and an abort switch (not shown) are mounted on the main body operation panel 28. When each switch is pressed, the CPU 37 detects that the switch has been turned on via the input port. The PSU 25 in the figure is a power supply unit.

FIG. 3 shows an LSYNC output counter circuit comprising a counter, a comparison value 1, a comparison value 2, a comparator 1, a comparator 2, and a waveform output circuit.
Is set to the counter value of one cycle of LSYNC, and the comparison value 2 is set to the value of the duty ratio. When the counter starts from 0, the “H” section ends when the comparison value 2 matches the counter first, and when the comparison value 1 matches, the “L” section ends and the section changes to the “H” section again. Such an operation can be repeated to start and stop the LSYNC signal by software. The output of the LSYNC output counter is output to the NIPU 33 which is an image processing unit, and the reading operation is output to the SBU 20 via the IPU.

As shown in FIG. 4, the image reading of the BOOK scanner starts, the stepping motor passes through, the speed becomes constant, and the reading of image data starts. The image reading data is output from the SCSI controller to the personal computer via the memory buffer of the SIBC 35, but if the CPU does not receive the image data in time, the usage rate of the memory buffer of the SIBC increases. Output a near full memory interrupt signal. When the program of the CPU 37 receives the near full interrupt, the image reading is interrupted. Therefore, the LSYNC output counter output by the LSYNC in FIG. 3 is stopped, and the stepping motor is slowed down and stopped. At this time, the LSYNC output counter stores the phase of the LSYNC whose reading has been stopped. Then, when the image reading is restarted, the stepping motor is slewed up and down in the reverse direction and stopped so that the reading can be resumed from the position where the reading was interrupted, that is, when the reading has been interrupted, that is, at the position where the reading was interrupted. Then, the buffer memory is emptied and the reading is started again, so it goes through,
When the speed becomes constant, the count of the LSYNC output counter is permitted, and the image reading is restarted. As shown in FIG. 4, the phase relationship between LSYNC and the stepping motor is maintained in synchronization, so that the phase relationship between when image reading is stopped and when image reading is started again does not deviate. Even if the image is temporarily stopped, there is no shift in the main scanning direction, so that a high-accuracy image can be captured.

(Invention of claim 2) In the image reading apparatus of claim 1, the image reading of the BOOK scanner starts, the stepping motor goes through, the speed becomes constant, the reading of image data starts, and the near full interrupt signal from the SIBC 35 is issued. Is output, the CPU stops reading, the stepping motor is slewed down and stopped,
Next, through-up and through-down are performed in the opposite direction. Then, through-up is performed in order to resume reading again. In the invention of claim 1, the reading stop position is at a constant speed, but in the invention of claim 2, the stepping motor is operated as shown in FIG. In order to increase the speed, it is conceivable that mechanical vibration occurs when the speed becomes constant. Therefore, by returning to the sub-scanning direction slightly more by the stepping pulse, and controlling the image reading to be restarted with a delay of the stepping motor pulse that is delayed when the speed becomes constant, the image reading is performed after the mechanical vibration is reduced. High-speed, high-accuracy image capture can be realized.

(Invention of claim 3) In the image reading apparatus of claim 1, if the LSYNC is not inputted even after the elapse of one cycle t + α of LYNC in the image processing unit NIPU as shown in FIG. Pseudo LS with pseudo LSYNC circuit
Generates YNC and SBU (Sensor board unit)
Output to As a result, the CCD line sensor does not saturate, so that even if a near-full interrupt occurs and the image reading is interrupted, the image can be captured immediately.

[0021]

According to the first aspect of the present invention, the control of the start and stop of the LSYNC output signal and the control of the stepping motor for controlling the operation of the traveling body are simultaneously performed by the program of the CPU, so that the image reading is interrupted. Even after restarting, the phase shift between the LSYNC signal phase and the image reading start position is reduced by synchronizing, so that it is reduced.
The distortion of the read image can be effectively reduced. According to the second aspect, even when the stepping motor is controlled at a high speed, when the memory buffer becomes almost full due to the program processing of the CPU, the stepping motor is returned to the sub-scanning direction by a few more pulses and read. When reading is started, the reading speed becomes constant and the reading is restarted with a delay of several pulses, so that mechanical vibration can be minimized and high-speed, high-precision image reading can be performed. According to the third aspect of the invention: When image reading is not performed, a pseudo LSYNC is output from the image processing unit, so that a clock is always input to the CCD line sensor at regular intervals, thereby correcting saturation of the CCD line sensor. As a result, image reading quality can be improved.

[Brief description of the drawings]

FIG. 1 is an overall structural diagram of an image reading apparatus according to the present invention.

FIG. 2 is an overall block diagram of the image reading apparatus according to the present invention.

FIG. 3 is an LSYNC output counter circuit.

FIG. 4 is a diagram showing a phase relationship between LSYNC and a stepping motor.

FIG. 5 is a diagram for explaining output timing of pseudo LSYNC.

FIG. 6 is a diagram showing a phase relationship between a conventional LSYNC and a stepping motor.

[Explanation of symbols]

Reference numeral 1: platen glass, 2: first mirror, 3: illumination lamp,
4 Second mirror, 5 Third mirror, 6 CCD, 7 Running motor, 8 Document tray, 9 Pickup roller, 10 Registration roller pair, 11 Transport drum, 12
... conveying roller, 13 ... conveying roller pair, 14 ... discharge roller pair, 15 ... contact image sensor, 20 ... SBU, 2
1 SCU, 23 RCU, 24 IOB, 26 Optional IPU, 30 ADU, 33 SCU, 35 S
IBC, 36: SCSI controller, 37: CPU,
38 ROM, 39 RAM

Claims (6)

[Claims] An image is read by main scanning for reading image data line by line from a CCD line sensor and sub-scanning by driving a stepping motor. When a buffer memory for storing image data in a document reading operation becomes nearly full, reading is performed. Means for outputting a CCD line period signal to an image processing unit in an image reading apparatus which stops operation and starts reading again when the memory buffer becomes empty;
A counter for counting a CD line cycle signal; and means for controlling count inhibition and permission. When the buffer memory is nearly full, the counter is inhibited at the stopped position and the CCD line cycle at that time is stopped. An image reading apparatus, wherein a phase of a CCD line cycle signal is matched with a position driven by a stepping motor by holding a signal phase and starting counting at a position where reading is started again, thereby reducing image distortion. 2. The image reading apparatus according to claim 1, wherein the counter is a counter with a built-in CPU, and the counter is controlled by software to inhibit or allow counting. 3. The image reading apparatus according to claim 1, wherein the reading operation is stopped and returned in the sub-scanning direction when the buffer memory is almost full, and the buffer memory is empty. An image reading apparatus for resuming image reading by advancing in the sub-scanning direction by an amount returned in the sub-scanning direction. 4. The image reading apparatus according to claim 3, wherein the distance returned in the sub-scanning direction is such that the image reading can be resumed after a certain speed at the time of resuming the reading, and the influence of the mechanical vibration can be reduced. An image reading apparatus characterized in that the reading is restarted after the reduction and the distortion of the read image is reduced. 5. The image reading apparatus according to claim 1, wherein when reading is not performed, a pseudo CC is read.
Means for generating a D-line periodic signal;
An image reading apparatus which outputs a line cycle signal to a CCD line sensor and does not saturate the CCD even when reading is not being performed. 6. An image processing apparatus comprising the image reading device according to claim 1.