JP2000307829A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of a joint caused by reading interrupt due to the fullness of not transferred data in a buffer in the middle of reading an image, while thinning read data. SOLUTION: A thinning timing managing means 22 starts to count sampling signals at an image reading start. When the not transferred data become full in buffer, the means 22 stores a count value, and a CPU 19 and a carriage drive control part 21 store a reread start position. The part 21 makes a read position backward and a reread position forward. The CPU 19 outputs a reset signal to the means 22, when the reading position reaches the prescribed position on this side of the reread start position. The means 22 adjusts thinning timing at the reread start position by starting to count at a prescribed value corresponding to a reset position.

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 capable of reading a document image used for a facsimile, a digital copying machine, a scanner, and the like.

[0002]

2. Description of the Related Art Conventionally, an image reading apparatus has been used as an image input section of a scanner, a facsimile, a digital copying machine, and the like, and is generally connected to a computer such as a host personal computer, a communication device, or the like. is there. For example, when the image reading apparatus is connected to a host personal computer, the SCSI (Small C
output System Interface)
In some cases, the image data reading speed of the image reading device is higher than the image data transfer speed by an interface such as the above. In order to smoothly perform such an interface transfer, a buffer memory (hereinafter referred to as a buffer) for temporarily storing image data read by an image reading device before transferring the image data to an external device via an interface. (Abbreviated).

As a mode of providing a buffer, it is conceivable to provide a buffer having a capacity for storing one screen of image data which can be read by an image reading apparatus. However, if a buffer having such a large memory capacity is introduced, The cost is high. On the other hand, recently, there has been an increasing demand for lower prices, and it is necessary to reduce the capacity of the buffer in order to meet the demand. In order to simultaneously satisfy the demand for smooth interface transfer and the demand for price reduction, it is necessary to provide a buffer having a capacity smaller than the capacity for storing image data for one screen.

When an image for one screen is read by such a small buffer, the buffer is full of untransferred image data (hereinafter abbreviated as buffer full).
The image reading operation is interrupted by temporarily suspending the carriage equipped with an image sensor that converts the intensity of light incident on the original image into an electrical signal until all image data in the buffer is transferred. Have to do it. Then, after all the image data has been transferred, the reading operation must be restarted by moving the carriage. The above series of operations is referred to as a re-read operation or a restart operation. In order to use a small-capacity buffer, it is necessary to incorporate a mechanism for performing such a re-reading operation into the image reading apparatus.

[0005] Further, as workstations and personal computers have become more sophisticated in recent years, image editing, electronic filing, and character input processing by OCR (optical character reader) have been accelerated. Along with this, image scanners that can easily input document images with good reproducibility have become widespread.
Further, higher resolution of image input is required. Therefore, first, a conventional image reading apparatus including a large-capacity buffer for storing image data for one screen will be described with reference to the drawings, and then a high resolution technology applied to the image reading apparatus will be described. .

FIG. 18 is a sectional view showing an example of the configuration of a conventional image reading apparatus. As shown in FIG. 18, when reading a document, the document 2 is placed on the document glass 3 of the image reading device 1. The image reading apparatus 1 includes a CCD (Charge Coupled Device) line sensor 10 that detects reflected light on the surface of the original 2 through the original glass 3. The CCD line sensor 10 is fixed to the carriage 4 and the motor 5
Drives the drive wire 6 coupled to the carriage 4 to scan the CCD line sensor 10. The carriage 4 has a light source lamp 7 for illuminating the surface of the original 2 and a CCD.
A reflection mirror 8 and an imaging lens 9 for guiding light reflected on the surface of the document 2 to the line sensor 10 are provided.

FIG. 19 is a block diagram showing an example of the configuration of the conventional image reading apparatus shown in FIG. The electric signal obtained from the CCD line sensor 10 is amplified, sampled and held by the analog processing circuit 13. The output of the analog processing circuit 13 is converted into a digital signal by an A / D converter (analog-digital converter) 14. The image processing circuit 15 performs image processing such as shading correction, filter processing, and enlargement / reduction processing on the image data output from the A / D converter 14. The image data is temporarily stored in the image processing memory 16 when the image processing is performed in the image processing circuit 15. The image data processed by the image processing circuit 15 is transmitted to the interface 1
7 and exchanged with an external device. These CCD
The operation timing of the line sensor 10, the analog processing circuit 13, the A / D converter 14, the image processing circuit 15, etc.
It is provided from the timing generation circuit 18. On the other hand, the motor 5 is controlled by the carriage drive control unit 12, and a CPU (Central Processing Unit) 19 controls the entire electric circuit of the image reading apparatus 1 including the carriage drive control unit 12. The control program of the CPU 19 and the contents of the work are stored in a memory 20 for the control program and the work. 20 and 21 show the operation of the image reading apparatus shown in FIGS.
This will be described with reference to FIG. In this description,
It is assumed that the image reading device 1 is connected to an external host computer (not shown).

First, when an external host computer instructs the image reading device 1 to read a document,
The CPU 19 sends the motor 5 to the carriage drive control unit 12.
To control the driving of. Under the control of the carriage drive control unit 12, the motor 5 starts driving the carriage 4, and the carriage 4 moves to the position of the white reference member 11. The CPU 19 detects that the carriage 4 has reached that position, stops the carriage 4, and then turns on the light source lamp 7. The luminous flux of the light source lamp 7 is the white reference member 1
The reflected light is formed on the CCD line sensor 10 by the imaging lens 9 and photoelectrically converted. CC at this time
The output of the D line sensor 10 is amplified by the analog processing circuit 13 and input to the A / D converter 14, where
The D-converted image data is stored in the image processing circuit 15 as bright correction data. After the reading of the white reference member 11 is completed, the CPU 19 turns off the light source lamp 7 and starts the reading operation in the dark. The output signal of the CCD line sensor 10 at this time is similarly amplified by the analog processing circuit 13 and input to the A / D converter 14, where the A / D converted data is used as dark correction data by the image processing circuit 1.
Stored at 5. The image processing circuit 15 creates shading correction data from the light correction data and the dark correction data. Using this shading correction data, shading correction will be performed on the document read data in the future.

After the shading correction data is obtained, C
The PU 19 turns on the light source lamp 7 again and instructs the carriage drive control unit 12 to drive the carriage 4 at a constant speed. The moving speed of the carriage 4 at this time is set in accordance with the designation of the resolution in the sub-scanning direction set in advance by the host computer. For example, when reading in the sub-scanning direction has a resolution of 600 dpi (dot per i
nch), the accumulation time (corresponding to the shutter time) of the CCD line sensor 10 is 8 msec. Is set to 5.25 mm / s. CPU
When the carriage 19 detects that the carriage 4 has reached the document reading start position, it outputs an operation command to the timing generation circuit 18 to start the image reading operation. The reflected light of the reading portion of the original 2 forms an image on the CCD line sensor 10 in the same manner as when the shading correction data is obtained.
The data is converted into digital data by the / D converter 14. The image processing circuit 15 performs shading correction on the image data using, for example, shading correction data stored earlier. The data after the correction calculation is
After the image processing circuit 15 further performs a filter operation, enlargement / reduction processing, and the like, the image data is output to a host computer or the like through the interface 17.

The relationship between the sampling signal and the image data processed by the image processing circuit 15 when the accumulation time of the CCD line sensor 10 is generalized to δt will be described with reference to FIG. CC shown in FIG.
In the sampling signal of the D line sensor 10 (pulse interval corresponds to the accumulation time), the signal read in the section from t to t + δt is the nth output data of the output data of the CCD line sensor 10 shown in FIG. Data, delayed by one line with respect to the sampling signal, and t + δt
To t + 2δt. Similarly, the signal read in the interval from t + δt to t + 2δt is delayed by one line as the (n + 1) th output data from t + 2δt to t + 2δt.
It is output in the section of + 3δt.

The reading trajectory in the sub-scanning direction in the normal reading operation described above causes a moving average effect due to the movement of the carriage 4 during the accumulation time δt. Here, the moving average effect will be described with reference to FIG. It is assumed that the reading position of the CCD line sensor 10 is between the coordinates x20 and x21 at time t. This reading position moves from the coordinates x21 to x22 with the movement of the carriage 4 during the accumulation time δt. Looking at the pixel between the coordinates y20 and y21, CC
The D-line sensor 10 calculates coordinates x20 to x2 indicated by oblique lines.
This means that the average value of the reflected light in the area between 2 has been read. This results in reduced resolution in the sub-scanning direction.

In order to solve this problem, there is a technique for suppressing the resolution in the sub-scanning direction by reducing the moving average effect in the sub-scanning direction. The technique is a sub-scanning fine reading mode in which the moving speed in the normal image reading mode is set to 1 / n of the moving speed, and the data read by the CCD line sensor 10 is thinned out to 1 / n lines. .

A sub scanning fine reading mode in which the moving speed in the normal image reading mode is set to 1/4 the speed of the moving image and the read data is thinned out to 1/4 line will be described with reference to FIGS. 22 and 23. I do. Since the read data is thinned out to 1/4 line, t
The (n + 1) th data read next to the nth output data read in the section from t to t + δt is t + 4δt
And data of a signal read in a section from t to 5 + δt. For example, it is assumed that the reading position is between the coordinates x30 and x31 in FIG. 23 at time t. Since the moving speed is set to 1/4 the speed of the normal image reading mode, the reading position moves between the coordinates x32 and x33 with the movement of the carriage 4 when the accumulation time δt has elapsed. Looking at the pixels between the coordinates y30 and y31, the CCD line sensor 10 has read the average value of the reflected light in the region between the coordinates x30 and x33 indicated by oblique lines. Thus, the moving average effect can be reduced by shortening the distance that the carriage 4 moves during the accumulation time δt.

The image data read by displacing the optical system in the main scanning direction for each line of the sub-scanning is used as a CCD.
By restoring the original image from the staggered image group obtained by displacing the line sensor 10, the optical resolution of 2
There is a technique for obtaining an image having a resolution higher than the resolution of the sensor by generating resolution information in the double main scanning direction. The mode in which the optical system is read by displacing the optical system is called a swing (vibration) reading mode.

Here, reading performed by displacing the optical system will be described with reference to FIGS. FIG.
, The x direction is the sub-scanning direction, and the y direction perpendicular to the x direction is the main scanning direction. In the swing reading mode, reading is performed while the CCD line sensor 10 is vibrated in the main scanning direction by half a pixel. FIG. 25 shows the relationship among the sampling signal, the output data, and the vibration driving waveform in the swing reading mode. In the vibration drive waveform shown in FIG. 25C, if one end of the vibration is C phase and the other end is D phase, the vibration drive waveform is horizontal and stable in C phase and D phase. FIG. 25 (a)
Since the vibration driving waveform is stable in the C phase in the interval from t to t + δt in accordance with the sampling signal shown in FIG. 25, the image is read, and as shown in FIG. It is output during t + 2δt.
The next reading of the (n + 1) th output data is t + 4δ
The operation is performed in a section from t to t + 5δt. Coordinate x in FIG.
Assuming that an area from 40 to x41 and coordinates y40 to y41 is an n-th output data reading area, an area from coordinates x42 to x43 and coordinates y42 to y43 is an n + 1-th output data reading area.

[0016]

First, the conventional image reading apparatus capable of reading in the sub-scanning fine reading mode has a buffer having a capacity for storing image data for one screen, so that the cost is increased. ing. If the capacity of the buffer is to be reduced in order to reduce the price while the phase of the sampling signal is not managed, in the sub-scanning fine reading mode, for example, as shown in FIG.
Although the reading position is stopped between 50 and x51, reading is not resumed from the coordinate x51 and the coordinate x52 is not resumed.
When the reading is restarted from the beginning, an inconsistency occurs in the thinning-out timing, and the re-reading start position is shifted in the sub-scanning direction, so that the seam becomes visible.

Second, the buffer capacity of a conventional image reading apparatus capable of reading in a swing reading mode in which reading is performed while causing relative vibration in the main scanning direction between the carriage and the document is smaller than the capacity for storing image data for one screen. In the case of setting, if the phase of the vibration drive waveform is not managed, for example, as shown in FIG. 28, the pixel G0 at the reading position when reading is interrupted due to buffer full should be at the reading position P1 in the re-reading operation. It becomes P2, and C phase-D phase-C phase-D
The phase and the image repeatedly read become the C phase-C phase-D phase-C phase, and the phase of the vibration is inconsistent, and the seam becomes visible.

Therefore, in the present invention, in the first problem,
It is an object of the present invention to make it impossible to visually recognize a seam in an image caused by a buffer full in a sub-scanning fine reading mode.

Another object of the present invention is to provide a swing reading mode in which a seam in an image caused by buffer fullness cannot be visually recognized.

[0020]

In order to solve the first problem, an image reading apparatus according to the present invention comprises: a sensor for reading an image to be read in synchronization with a sampling signal and converting the image into an electric signal; Moving means capable of moving the reading position of the sensor forward and backward relative to the object to be read, conversion means for converting an electric signal output by the sensor moving forward to read data, and conversion means Thinning means for thinning the read data at a predetermined rate with respect to the number of sampling signals; and a reading position that moves forward until the reading is interrupted due to the inability to process the reading data, and that the reading position moves backward after the reading is interrupted. The first drive signal controls the movement of the reading position so as to move forward again, Movement control means for resetting the sampling signal at a predetermined reset timing according to the first drive signal before the device passes a re-read start position following the read position at the time of reading interruption; There is provided a timing management means for matching the thinning timing by the thinning means before and after the interruption of the reading in accordance with the number of sampling signals generated before passing through the re-read start position.

In the image reading apparatus according to the present invention, when reading data processing becomes impossible due to a buffer full or the like and reading is interrupted, the movement control means controls the moving means to change the reading position of the sensor. Moves backward from the re-reading start position. When the movement control means again moves the reading position of the sensor forward by the movement means and starts re-reading from the re-read start position after the processing of the read data becomes possible, the timing management means sets the reset timing. The number of sampling signals generated before the reading position passes through the re-reading start position matches the thinning-out timing of the read data before and after the reading is interrupted, so that the thinning-out timing can be kept from shifting. Created in the scanned image due to the displacement,
It is possible to remove a seam of about the pixel width of the sensor.

Further, the image reading apparatus according to the present invention comprises:
In order to solve the second problem, a sensor that reads an image of an object to be read in synchronization with a sampling signal and converts the image into an electric signal, and moves the reading position of the sensor forward and backward relative to the object to be read. Movable and
A moving means capable of oscillating while maintaining a predetermined timing between the sampling signal in the right and left directions different from the front and the rear, a converting means for converting an electric signal obtained by the sensor into read data, and a converting means for obtaining the data. The reading position is moved forward while oscillating right and left until the reading is interrupted due to the inability to process the read data to be read, and the reading position is moved backward after the reading is interrupted after the reading position moves backward and vibrates again. Moving control means for controlling the movement of the reading position with the first drive signal, controlling the vibration of the reading position with the second drive signal, and resetting the sampling signal at a predetermined reset timing according to the second drive signal And the vibration to match the phase of the vibration before and after the reading is interrupted In which and a vibration phase control means for controlling the relationship between the phase and the first drive signal.

In the image reading apparatus according to the present invention, when reading data cannot be processed due to a buffer full or the like and reading is interrupted, the movement control means controls the moving means to change the reading position of the sensor. Moves backward from the re-reading start position. When the movement control means moves forward again while oscillating the reading position of the sensor by the movement means and starts re-reading from the re-read start position after processing of the read data becomes possible, the vibration phase control means By controlling the relationship between the phase of the vibration and the first drive signal so as to match the phase of the vibration in the reading before and after the interruption of the reading, it is possible to prevent the mismatch of the phase of the vibration, so that the phase deviation of the vibration can be prevented. Thus, a seam formed in the read image and having a width of about the sensor pixel can be removed.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image reading apparatus according to a first aspect of the present invention includes a sensor for reading an image of an object to be read in synchronization with a sampling signal and converting the image into an electric signal, and a sensor relatively to the object to be read. Moving means capable of moving the reading position forward and backward, converting means for converting an electric signal output by a sensor moving forward to read data, and reading data obtained by the converting means with respect to the number of sampling signals. A thinning means for thinning out at a predetermined rate, and a reading position that moves forward until reading is interrupted due to inability to process read data, and that the reading position moves backward after reading is interrupted and then moves forward again. The movement of the reading position is controlled by the drive signal of No. 1 and the reading position is set to the reading position when the reading is interrupted. And movement control means for resetting the sampling signal at a predetermined reset timing corresponding to the first drive signal before passing through the subsequent re-read start position,
Timing management means for matching the thinning timings by the thinning means before and after the interruption of the reading according to the number of sampling signals generated between the predetermined reset timing and the reading position passing the rereading start position. It is.

With this arrangement, when reading data is thinned out, for example, in the reading mode such as the sub-scanning and fine reading mode, when reading data processing is disabled and the image reading is interrupted, the pixels read by the sensor can be visually recognized. Even when large, the seam in the image can be made invisible.

The image reading apparatus according to a second aspect of the present invention is the image reading apparatus according to the first aspect, wherein the moving means moves the reading position to the right and left different from the front and rear with respect to the object to be read. The movement control means is configured to be capable of relatively oscillating according to the sampling signal, and the movement control means is configured to be capable of controlling the vibration performed by the movement means. And a vibration phase control means for giving the coincidence timing to the movement control means.

Thus, in the reading mode such as the swing reading mode, when the reading of the image is interrupted due to the inability to process the read data in the reading mode such as the swing reading mode, the sensor reads. Even when the pixels are large enough to be visible, the seams in the image can be made invisible.

An image reading apparatus according to a third aspect of the present invention includes a sensor for reading an image to be read in synchronization with a sampling signal and converting the image into an electric signal, and a reading position of the sensor relative to the object to be read. Moving means that can move forward and backward, and can vibrate while maintaining a predetermined timing between the sampling signal in the right and left directions different from the front and rear, and read the electric signal obtained by the sensor into read data. The converting means for converting, so that the reading position moves forward while oscillating right and left until the reading is interrupted due to the inability to process the read data obtained by the converting means, and the reading position moves backward after the reading is interrupted. The movement of the reading position is controlled by the first drive signal so that it moves forward while vibrating again from The movement control means for controlling the vibration of the reading position by the second drive signal and resetting the sampling signal at a predetermined reset timing according to the second drive signal, and aligning the phase of the vibration in the reading before and after the interruption of the reading. Vibration phase control means for controlling the relationship between the phase of the vibration and the first drive signal so as to cause the vibration phase to be controlled.

Thus, in the reading mode such as the swing reading mode, the sensor reads the image by moving the sensor while vibrating, and when the reading of the image is interrupted due to the inability to process the read data. Even when the pixels are large enough to be visible, the seams in the image can be made invisible.

According to a fourth aspect of the present invention, in the image reading apparatus according to the third aspect, the movement control means changes the frequency of the first drive signal based on the control of the vibration phase control means. This is to control the relationship.

Thus, the relationship between the phase of the vibration and the first drive signal can be controlled without changing the phase of the vibration of the sensor by changing the second vibration signal, thereby simplifying the structure of the moving means. it can.

An image reading apparatus according to a fifth aspect of the present invention is the image reading apparatus according to the third or fourth aspect, wherein the read data obtained by the conversion means is converted at a predetermined ratio to the number of sampling signals. Thinning means for thinning out, and timing management means for matching thinning timings by the thinning means before and after the interruption of reading according to the number of sampling signals generated from a predetermined reset timing until the reading position passes the rereading start position. Is further provided.

With this arrangement, when reading data is thinned out, for example, in the reading mode such as the sub-scanning and fine reading mode, when reading data processing is disabled and the reading of the image is interrupted, the pixels read by the sensor can be visually recognized. Even when large, the seam in the image can be made invisible.

According to a sixth aspect of the present invention, in the image reading device according to any one of the first to fifth aspects, the movement control means is configured to control the frequency of the first drive signal to be constant. After that, a predetermined reset timing is generated.

Thus, before the reset timing, the frequency of the first drive signal can be reduced, and a run-in period for stabilizing the moving speed of the reading position can be provided.

An image reading apparatus according to a seventh aspect of the present invention is the image reading apparatus according to any one of the first to sixth aspects, wherein the reading data is stored as the processing of the read data, And a buffer memory for notifying at least the movement control means that the processing has become impossible when the read data is accumulated, and stopping the accumulation of the read data to transfer the accumulated data.

As a result, the interface transfer can be smoothly performed using a buffer memory having no capacity for storing all the image information at a time, and the cost can be reduced by reducing the capacity of the buffer memory.

(Embodiment 1) An image reading apparatus according to Embodiment 1 of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram showing one configuration example of the image reading device according to the first embodiment of the present invention. In the image reading apparatus 1A shown in FIG. 1, the thinning timing management means 2 which is not provided in the conventional image reading apparatus 1 shown in FIG.
2 has been added. The thinning timing management means 22 manages the timing for thinning out the read data supplied to the image processing circuit 15. In the image reading apparatus 1A according to the first embodiment, when the image processing memory 16 as a buffer memory becomes full of accumulated read data, it notifies the buffer full and transfers data. The reading position of the CCD line sensor 10 moves forward in the sub-scanning direction relative to the document to be read until the buffer full is notified. Until the buffer full is notified, the thinning-out timing management means 22 operates according to the information given in advance, for example, once every n times the sampling signal is given, at a rate of one time.
The image processing circuit 15 is permitted to read the output signal of 0 as read data. For this purpose, the thinning-out timing management means 22 counts the sampling signal from the time when the carriage drive is started.

When the buffer full is notified, the thinning-out timing management means 22 stops counting the sampling signal and holds the count value of the sampling signal when the buffer is full. At this time, at the same time, the thinning-out timing management means 22 outputs the CC signal regardless of the generation of the sampling signal.
Reading the output of the D line sensor 10 as data is prohibited for the image processing circuit 15.

The image reading apparatus 1A according to the first embodiment has, for example, the configuration shown in FIG. 18 as shown in FIG. 3, and the carriage 4, the motor 5, and the driving wire 6 correspond to the moving means. The CPU 19 and the carriage drive control unit 21 in FIG. 1 serve as movement control means for controlling the movement means. The analog processing circuit 13 and the A / D converter 14 are conversion means for converting an electric signal output from the CCD line sensor 10 into read data, and the image processing circuit 15 and the thinning timing management means 22 constitute a thinning means. ,
The thinning-out timing management unit 22 is also a timing management unit.

When the buffer full is notified, the CPU 1
9 and the carriage drive control unit 21 store the reading position of the CCD line sensor 10. Specifically, CCD
This is a positional relationship between the sampling signal of the line sensor 10 and the carriage drive pulse in the sub-scanning direction of the carriage drive controller 21. Thereafter, the CPU 19 and the carriage drive control unit 21 move the carriage 4 in the sub-scanning direction in a direction opposite to the reading direction (forward) (backward). At this time, the CPU 19 and the carriage drive control unit 21 store the distance moved in the opposite direction (rearward). next,
The carriage drive control unit 21 drives the carriage 4 in the reading direction in the sub-scanning direction. The carriage 4 enters the constant speed motion after the running period, and is controlled by the CPU 19 and the carriage drive control unit 21 so as to cross the re-read start position during the constant speed motion. The CPU 19 outputs a reset signal to the thinning-out timing management means 22 when the carriage 4 reaches a predetermined distance before the re-read start position (a predetermined reset timing). Upon receiving the reset signal, the thinning-out timing management unit 22 sets the initial value of the counter based on the count value when the buffer is full. The reset signal is issued before the position where the buffer full was once issued. When the count value of the counter reaches the count value when the buffer is full, the thinning timing management unit 22 permits the image processing circuit 15 to read the read data.

Prior to describing the structure of the thinning-out timing management means 22, the structure and operation of the carriage drive control unit 21 will be described with reference to FIGS. In FIG. 6, a carriage drive control unit 21 includes a clock signal generator 2 for generating a clock signal of a predetermined cycle.
8 are provided. The counters 29, 31, and 33 count clock signals generated by the clock signal generator. Registers 30a and 30b in which set values C1 and C2 are written from the CPU 19, respectively, are provided corresponding to the counter 29. Similarly, registers 32a and 32b in which set values C3 and C4 are respectively written from the CPU 19 are provided corresponding to the counter 31. A register 34 for reading and holding the count value of the counter 33 every time the sampling signal SU is generated.
a and a register 34 b to which a value is written from the CPU 19 are provided corresponding to the counter 33. Counter 2
9 and the set value C1 of the register 30a, and a comparator 3 which generates a coincidence signal when both coincide with each other.
5 are provided, and the counters 29, 31, and 33 are simultaneously reset by the comparison result of the comparator 35.
The reset counters 29, 31, 33 restart counting from 0 again. Further, a comparator 36 is provided which compares the count value of the counter 29 with the set value C2 of the register 30b and generates a match signal when the two match. Similarly, the count value of the counter 31 and the register 3
2a is compared with the set value C3, and when they match, a comparator 37 that generates a match signal, and the count value of the counter 31 is compared with the set value C4 of the register 32b, and when they match, the two match. A comparator 38 for generating a signal is provided.

The output control section 40 generates a motor excitation signal (sub-scanning direction carriage driving pulse which is a first driving signal) based on the coincidence signal output from both of the comparators 35 and 36. Further, the output control unit 42
A so-called toggle output in which a high level and a low level are alternately inverted and output each time a coincidence signal is input from the CPU.

The motor driver 50 drives the stepping motor 5 based on the sub-scanning direction carriage driving pulse output from the output control section 40. On the other hand, the phase coefficient counter 44 receives the output signals of the output control units 40 and 41 whose phases are shifted by 90 ° from each other as two-phase inputs, and measures the rotation amount of the motor 5, that is, the movement amount of the carriage without the intervention of the CPU 19. Is done. The register 45 stores the sampling signal SU
The count value of the counter 44 is read and held each time the error occurs. The register 45 can be read from the CPU 19, and the CPU 19 can obtain the count value of the counter 44 held in the register 45, that is, the position information of the carriage 4 every time an interruption by the sampling signal SU occurs.

A value is written into the register 46 from the CPU 19. The comparator 47 compares the set value of the register 46 with the count value of the counter 44, and generates a match signal when the two match. On the other hand, the both-edge detector 48 detects both edges of the toggle signal output from the output controller 42 and generates a pulse signal corresponding to both edge positions. When the comparator 47 generates a coincidence signal, the gate circuit 49 outputs a pulse signal having a specified width based on the signals from the two edge detection units 48. The output of the gate circuit 49 is input to the CPU 19, and the CPU 19 recognizes the output of the gate circuit 49 as an interrupt.

FIG. 7 is a timing chart showing the operation of the carriage drive control unit 21 before the occurrence of a buffer full and at the time of occurrence. Registers 30a and 30 shown in FIG.
The set values C1 to C4 of b, 32a, and 32b are set to have the following relationship with each other. That is, the value of the set value C2 is set to half of the set value C1, and the set value C
3 is set to a half of the sum of the set value C1 and the set value C2, and the set value C4 is set to a half of the held value C2. The count values of the counters 29, 31, and 33 are shown in FIG.
As shown in (a), (c), and (f), each time the value becomes equal to the set value C1, the signal is reset by the coincidence signal of the comparator 35, so that a sawtooth waveform is obtained. Then, since the set values C1 to C4 are set as described above, the output of the output control unit 40 (FIG. 7B) until the count value of the counter 29 is 0 to C2.
) Becomes low level and becomes high level from C2 to C1, while the count value of the counter 31 is 0 to C4 and C4.
Since the output of the output control unit 41 (see FIG. 7D) becomes high level or low level from 3 to C1, and becomes low level or high level from C4 to C3, the output signals of the output control units 40 and 41 are output. Can be shifted by 90 °.

The CPU 19 outputs a buffer full signal BF (FIG. 7).
(See (h)), the motor 5 is stopped immediately, and the signal generation rule of the output control unit 41 is changed. That is, the low level is set by the match signal output when the count value of the counter 31 matches the set value C3, and the high level is set by the match signal output when the count value of the counter 31 matches the set value C4. After output, the motor 5 is rotated in the direction opposite to the reading direction. By such a setting change, the output control units 40 and 41
7 (e), the phase shift counter 44 functions as a down counter.

The CPU 19 stores the count value of the sampling signal SU (see FIG. 7 (g)) when the buffer full occurs. Also, the coarse position information PO1H and the minute position information PO1L at the point immediately before the count value are stored as the re-read start position when the buffer full is released. Then, the CPU 19 drives the motor 5 in a direction opposite to the reading direction so that the position of the carriage 4 is PO1H.
Then, the carriage 4 is driven until it is located rearward of the position where PO1L is detected (the direction opposite to the reading direction), and then the motor 5 is stopped to wait until the buffer full is released.
The down-counting of the counter 44 due to the reverse rotation of the motor 5 is performed until the value becomes smaller than the value shown in FIG.

FIG. 8 is a timing chart showing the operation of the carriage drive control section 21 after the buffer full release point. The release of the buffer full is transmitted from the image processing memory 16 to the CPU 19. Buffer full release CPU
When the CPU 19 recognizes that the PO1
H is written, and then PO1H is written to the register 34b.

The motor returning in the direction opposite to the reading direction is driven in the reading direction. Register 34
By writing PO1L in b, the comparator 39 compares the count value of the counter 33 (see FIG. 8C) that repeats the up-counting and resetting together with the driving of the motor 5 with the value PO1L of the register 34b. When this occurs, a match signal is output to the output control unit 42. The both-edge detector 48 detects both edges of the toggle signal (see FIG. 8D) output from the output controller 42, and outputs a pulse signal corresponding to both edge positions to the gate circuit 49 (FIG. 8).
(E)).

On the other hand, by writing PO1H to the register 46, the comparator 47 compares the count value (see FIG. 8A) of the counter 44, which is counted up with the driving of the motor 5, with the value PO1H set in the register 46. Compare,
When a match occurs, a match signal is output to the gate circuit 49 (see FIG. 8B).

When the output of the comparator 47 is input to the gate circuit 49, the gate circuit 49 generates an interrupt signal to the CPU 19 based on the output of the both-edge detector 48 generated next (see FIG. 8 (f)). Upon detecting this interrupt signal at time t20, the CPU 19 resets the sampling signal SU (see FIG. 8 (g)). The position at which the sampling signal SU is reset is determined before the re-reading start position and a predetermined distance from the re-reading start position.

Next, an example of the configuration of the thinning-out timing management means 22 will be described with reference to FIG. The thinning-out timing management means 22 includes a counter 50 for counting the sampling signal SU. Image processing circuit 15
In order to control the permission and prohibition of reading the read data, the thinning-out timing management means 22 includes a read permission signal generation circuit 51. The output of the counter when the buffer is full is held in the register 52. Register 5
3 holds a predetermined value, and the subtraction circuit 54 subtracts the value held in the register 53 from the value held in the register 52. The value calculated by the subtraction circuit 54 is held in the register 55 and becomes the initial value of the counter 50 at the time of reset. The comparison circuit 56 compares the count value of the counter 50 with the count value at the time of buffer full held in the register 52. Thereby, the comparison circuit 56
Gives the permission resuming timing at the time of resuming reading. The register 57 holds sampling signal thinning interval information indicating how much the read data is thinned with respect to the number of sampling signals SU. The read permission signal generation circuit 51 generates a read permission signal based on the value held in the register 57 and the output of the counter 50.

Next, the operation of the thinning-out timing management means 22 shown in FIG. 2 will be described with reference to FIGS. FIG. 3 is a sectional view schematically showing the configuration of the image reading apparatus. In FIG. 3, the position of the carriage 4 indicated by a dotted line is a position where the carriage 4 is present when reading is restarted, that is, a re-reading start position. Also,
In FIG. 3, the position of the carriage 4 indicated by a chain line is a position where the carriage 4 is retracted and stopped after the buffer is full.
The position of the carriage 4 indicated by a solid line is a position where a reset signal R for resetting the sampling signal SU is issued. In FIG. 3, x0 indicates a reading position when reading is restarted, and coordinates x1 indicate a reading position when resetting. Time t0 shown in FIG.
At this point, the register 52 holds the count value of the counter 50 when the buffer is full, and the register 55 holds the counter initial value at the time of reset. The carriage 4 is running from time t0 to time t1 shown in FIG. 4C, and after the time t1, the carriage 4 starts moving at a constant speed. At time t2 in FIG. 4C, the carriage 4 has reached the position indicated by the solid line in FIG. 3, and is synchronized with the falling edge of the carriage drive pulse shown in FIG.
The sampling signal SU shown in (a) is reset. At this time, the counter 50 is also reset, and the counter 50 starts counting from the counter initial value held in the register 55. At time t3 in FIG.
Reaches the read start position. At this time, the counter 50
Output matches the count value when the buffer is full. Therefore, the comparison circuit 56 can notify the read permission signal generation circuit 51 that the count value of the counter 50 matches the count value of the register 52. Therefore,
The read permission signal generation circuit 51 can instruct read permission at the same time when the carriage 4 reaches the re-read start position.

As described above, the image reading device 1
Is provided with the thinning-out timing management means 22, so that the reading positions x2 to x3 of the CCD line sensor 10 when stopping when the buffer is full and the reading positions x3 to x4 when re-reading is started as shown in FIG. At the same time.

(Embodiment 2) Next, an image reading apparatus according to Embodiment 2 of the present invention will be described with reference to FIGS. As can be seen by comparing the image reading device 1A of the first embodiment shown in FIG. 1 with the image reading device 1B of the second embodiment shown in FIG. Is different. In order to read an image in the swing reading mode, the carriage drive control unit 23 shown in FIG. 9 includes, in addition to the function of the carriage drive control unit 21 shown in FIG. 6, a relative vibration in the main scanning direction (rightward and leftward) between the carriage and the document. It has the function of controlling The vibration of the carriage 4 in the main scanning direction caused by the actuator 27 is synchronized with the operation of capturing an electric signal output by the CCD line sensor 10 as image reading data. The vibration phase control means 24 controls the phase of the vibration in the main scanning direction. Since the phase of the vibration in the main scanning direction stopped when the buffer is full is arbitrary, the vibration phase control means 24 stores the phase of the vibration in the main scanning direction when the buffer is full, and vibrates at the same phase when re-reading is resumed. The carriage drive control unit 23 is controlled at the same time.

FIG. 10 is a block diagram showing an example of the configuration of the carriage drive control section 23. Compared to the carriage drive control unit 21 according to the first embodiment shown in FIG. 6, the carriage drive control unit 23 shown in FIG. 10 includes a main scanning direction carriage drive pulse (second drive signal) for controlling the vibration of the actuator 27. 2) and an actuator driver 71 that drives the actuator 27 in accordance with the main scanning direction carriage drive pulse. However, the configuration of the carriage drive control unit 23 other than the main scanning direction carriage drive pulse generation unit 70 and the actuator driver 71 is the same as that of the carriage drive control unit 21.

FIG. 11 is a block diagram showing an example of the configuration of the vibration phase control means 24. The vibration phase control means 24 includes a swing phase determination circuit 60 for determining the phase of vibration when the buffer is full. Vibration phase determination circuit 60
Determines the phase of vibration when the buffer is full based on the carriage drive pulse in the main scanning direction. Vibration phase judgment circuit 6
The switch 61 is switched according to the determination result of 0.
The switch 61 outputs one of the output of the register 62 and the output of the register 63 to the subtraction circuit 64. The switch 61 selects whether the phase of the vibration is the C phase or the D phase when rereading is started after the reading is interrupted due to the buffer full. For example, C
Whether the timing of resetting the phase is one cycle before the oscillation cycle or 1.5 cycles before the timing of the re-reading is stored in the registers 62 and 63.
The subtraction circuit 64 subtracts the value held in the register 62 or 63 from the counter value at the time of buffer full held in the register 52. The output of the subtraction circuit 64 is held in the register 65. When the count value of the sampling signal counted after the counter 50 is reset becomes equal to the value held in the register 65, the comparison circuit 66 outputs a swing CCD activation start signal. By this swing CCD activation start signal,
The starting point of the vibration start timing of the carriage drive pulse in the main scanning direction is given.

FIG. 12 shows the vibration phase control means 2 shown in FIG.
4 is a diagram illustrating an example of the operation of FIG. At the time t2 shown in FIG. 12D, the sampling signal shown in FIG. 12A is reset by the sub-scanning direction carriage drive pulse shown in FIG. 12C. For example, FIG.
2 (d), the number of sampling signals from time t2 to time t4 is stored.
4 holds the count value of the counter 50. Therefore, at time t4 as shown in FIG. 12, the main scanning direction carriage drive pulse shown in FIG. 12B is triggered by the sampling signal.

As described above, since the image reading apparatus 1B shown in FIG. 11 includes the vibration phase control means 27, it is possible to match the phases of the vibrations before and after the interruption of the reading, as shown in FIG. When the buffer is full, the reading position between the coordinates y1 and the coordinates y2 can be accurately shifted from the coordinate y3 shifted by a half pixel to the position of the coordinate y4 when re-reading starts.

Third Embodiment Next, an image reading apparatus according to a third embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. FIG. 14 is a block diagram showing a configuration example of the image reading device according to the third embodiment of the present invention. Image reading apparatus 1C according to Embodiment 3 shown in FIG.
10 differs from the image reading apparatus 1B of the second embodiment shown in FIG. 10 in that the sampling signal SU of the timing generation circuit 18 is reset by the carriage drive control unit 23 of the image reading apparatus 1B of FIG. The purpose is to reset the positional relationship between the main scanning direction carriage driving pulse and the sub-scanning direction carriage driving pulse by adjusting the phase of the scanning direction carriage driving pulse. Further, the image reading apparatus 1C of the third embodiment causes the CPU 19 to reset the thinning-out timing management means 25 in response to the carriage driving pulse in the main scanning direction.

The thinning-out timing management means 2 shown in FIG.
The configuration 5 can be realized by the same circuit configuration as the thinning-out timing management unit 22 of the first embodiment shown in FIG. 2, for example, and the description of the configuration is omitted here. The thinning-out timing management units 22 and 25 differ only in how many initial values are set at reset timing. The configuration of the vibration phase control means 24 can be configured, for example, as shown in FIG. The vibration phase control means 24 includes a register 74 for holding a voltage value at which vibration driving in the main scanning direction is stabilized, an A / D converter 75 for converting a voltage value of a main scanning direction carriage drive pulse into a digital signal, A comparator 73 for comparing the output of the A / D converter 75 with the output of the A / D converter 75, and a phase determination circuit 76 for determining the phase of the main scanning direction carriage drive pulse when the buffer is full. The comparator 73 compares the voltage value of the main scanning direction carriage driving pulse, which is held in the register 74, with which the oscillation driving in the main scanning direction is stabilized,
A signal can be output each time the carriage drive pulse in the main scanning direction is in the vibration stable state in either the C phase or the D phase. The CPU 19 shown in FIG. 14 resets the positional relationship between the main scanning direction carriage driving pulse and the sub-scanning direction carriage driving pulse using the phase determination result of the vibration phase control unit 27 and the timing of stabilizing the vibration driving. The operation of the CPU 19 will be described with reference to the flowchart of FIG. The CPU 19 recognizes the positional relationship between the main scanning direction carriage driving pulse and the sub scanning direction carriage driving pulse when the buffer is full with respect to the main scanning direction carriage driving pulse based on the output of the phase determination circuit 76 (step ST1). Next, based on the output of the comparator 73, the CPU 19 determines the timing at which the vibration drive is stabilized (step ST2). Then, the CPU 19 determines the amount of fluctuation of the pulse frequency in the sub-scanning direction in order to synchronize the main-scanning-direction carriage driving pulse and the sub-scanning-direction carriage driving pulse (step ST3). The CPU 19
Registers 30a, 30b, 32 according to the determined variation amount
The frequency is changed by rewriting the values of a and 32b (step ST4).

Next, the operation of the vibration phase control means 27 shown in FIG. 15 will be described with reference to FIG. At a time t10 shown in FIG. 17D, a signal indicating that the vibration drive is stable is output to the CPU 19 from the comparator 73. At this time, the CPU 19 has already
, The phase of the carriage drive pulse in the main scanning direction when the buffer is full is recognized. And C
The PU 19 operates from the time t11 to the time t12 in FIG.
During this period, how much the frequency of the carriage driving pulse in the sub-scanning direction is changed is determined. According to the result, between time t10 and time t12, CPU 19
The values stored in 0a, 30b, 32a, and 32b are rewritten at appropriate timing. Further, the CPU 19 rewrites the values of the registers 30a, 30b, 32a, and 32b so that the sub-scanning direction carriage driving pulse returns to the original frequency after the time t12 between the times t11 and t12. At time t13 shown in FIG.
17 according to the carriage drive pulse in the main scanning direction of FIG.
The sampling signal shown in (a) is reset. The resetting at this time is the same as the resetting of the sampling signal SU described in the first embodiment except that the main scanning direction carriage driving pulse is used instead of the sub scanning direction carriage driving pulse. Here, since the positional relationship between the main scanning direction carriage driving pulse and the sub-scanning direction carriage driving pulse has already been adjusted, the number of sampling signals can be adjusted by using the main scanning direction carriage driving pulse. Therefore, FIG.
At the time t14 shown in (d), at the same time when the carriage 4 comes to the re-read start position, the thinning-out timing management means 25 in FIG.

As described above, the image reading apparatus according to the third embodiment shown in FIG. 14 is provided with the vibration phase control means 24 and the thinning-out timing management means 20. As shown in FIG. 13, the reading position between the coordinates y1 and the coordinates y2 when the buffer is full is changed to a coordinate y3 shifted by a half pixel when the reading is resumed.
Can be accurately shifted to the position of the coordinate y4.

In the first to third embodiments, the case where the sensor is the CCD line sensor 10 has been described. However, the sensors may not be linearly arranged.
It may have the following other arrays:

In the first to third embodiments, the case where the buffer memory is built in the image reading apparatus has been described. However, the buffer memory may be arranged outside.

The reason for interrupting the image reading may be other than the buffer full.

In this case, for example, a signal for instructing interruption may be given instead of the buffer full signal BF.

[0069]

As described above, according to the present invention, an image is read by thinning out read data, for example, in a reading mode such as a sub-scanning fine reading mode, or by moving a sensor while vibrating, for example, a swing reading mode. In the reading mode such as described above, when the reading of the read data is disabled and the reading of the image is interrupted, even if the pixels read by the sensor are large enough to be viewed, the seam in the image can be made invisible. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration example of an image reading device according to a first embodiment of the present invention;

FIG. 2 is a block diagram showing a configuration example of a thinning-out timing management unit shown in FIG. 1;

FIG. 3 is a sectional view showing an outline of the image reading device according to the first embodiment of the present invention;

FIG. 4 is a timing chart showing the operation of the image reading apparatus shown in FIG. 1 at the start of re-reading.

FIG. 5 is a conceptual diagram showing a relationship between a document image and a reading position according to the first embodiment;

FIG. 6 is a block diagram illustrating a configuration example of a carriage drive control unit illustrated in FIG. 1;

7 is a timing chart showing an example of the operation of the carriage drive control unit shown in FIG.

8 is a timing chart showing an example of the operation of the carriage drive control unit shown in FIG.

FIG. 9 is a block diagram showing a configuration example of an image reading device according to a second embodiment of the present invention;

FIG. 10 is a configuration diagram illustrating a configuration example of a carriage drive control unit illustrated in FIG. 9;

FIG. 11 is a block diagram showing one configuration example of a vibration phase control unit and a thinning-out timing management unit shown in FIG. 9;

12 is a timing chart showing an example of the operation of the image reading device shown in FIG.

FIG. 13 is a conceptual diagram illustrating a relationship between a document image and an image reading position according to the second embodiment.

FIG. 14 is a block diagram illustrating a configuration example of an image reading device according to a third embodiment of the present invention;

FIG. 15 is a block diagram showing an example of a configuration of a carriage drive control unit and a vibration phase control unit shown in FIG.

16 is a flowchart showing an example of the operation of the CPU shown in FIG.

FIG. 17 is a timing chart showing an example of the operation of the image reading apparatus shown in FIG.

FIG. 18 is a cross-sectional view showing one configuration example of a conventional image reading apparatus.

And FIG. 19 is a block diagram illustrating a configuration example of a conventional image reading apparatus.

FIG. 20 is a timing chart showing an example of an image reading operation in a conventional normal reading mode.

FIG. 21 is a conceptual diagram showing a relationship between a reading position in a conventional normal reading mode and a document image.

And FIG. 22 is a timing chart showing an example of an image reading operation in a conventional sub-scanning fine reading mode.

FIG. 23 is a conceptual diagram showing a relationship between a reading position and a document image in a conventional sub-scanning method fine reading mode.

FIG. 24 is a perspective view showing an example of the configuration of a conventional CCD line sensor.

FIG. 25 is a timing chart showing an example of the operation of a conventional image reading apparatus.

FIG. 26 is a conceptual diagram showing a relationship between a reading position and a document image in a conventional swing reading mode.

FIG. 27 is a conceptual diagram showing a problem of an image reading apparatus in a conventional sub-scanning sensor reading mode.

FIG. 28 is a conceptual diagram showing a problem of an image reading apparatus in a conventional swing reading mode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image reading apparatus 2 Document 4 Carriage 5 Motor 6 Drive wire 7 Light source lamp 8 Reflection mirror 9 Imaging lens 10 CCD line sensor 12, 21, 23 Carriage drive control unit 13 Analog processing circuit 14 A / D converter 15 Image processing circuit Reference Signs List 16 Image processing memory 17 Interface 18 Timing generation circuit 19 CPU 20 Program and work memory 22, 25 Thinning-out timing management means 24 Vibration phase control means

Claims (7)

[Claims] 1. A sensor for reading an image of an object to be read in synchronization with a sampling signal and converting the image into an electric signal, and a reading position of the sensor can be moved forward and backward relative to the object to be read. Moving means, converting means for converting the electric signal output by the sensor moving forward into read data, and thinning out the read data obtained by the converting means at a predetermined ratio with respect to the number of the sampling signals. Thinning means, so that the reading position moves forward until the reading is interrupted due to the inability to process the read data, and after the reading interruption, the reading position moves rearward and then moves forward again. The movement of the reading position is controlled by the first drive signal, and the reading position is read. Movement control means for resetting the sampling signal at a predetermined reset timing according to the first drive signal before passing through a re-read start position following the read position at the time of the interruption of taking, and Timing management means for matching the thinning-out timing by the thinning-out means before and after the interruption of the reading in accordance with the number of the sampling signals generated until the reading position passes the re-reading start position. Characteristic image reading device. 2. The movement control device according to claim 1, wherein the movement unit is configured to be capable of oscillating the reading position relative to the object to be read in a rightward direction and a leftward direction different from the front and rear directions in accordance with the sampling signal. The means is configured to control the vibration performed by the moving means, and counts the number of the sampling signals after the reset timing to set a timing for matching the phase of the vibration before and after the interruption of the reading. 2. The image reading apparatus according to claim 1, further comprising: a vibration phase control unit provided to the movement control unit. 3. A sensor for reading an image of an object to be read in synchronization with a sampling signal and converting the image into an electric signal, and a reading position of the sensor can be moved forward and backward relative to the object to be read. Moving means capable of oscillating while keeping a predetermined timing between the sampling signal in the right and left directions different from the front and the rear, and converting the electric signal obtained by the sensor into read data Means, so that the reading position moves forward while oscillating in the right and left directions until the reading is interrupted due to the inability to process the read data obtained by the conversion means, and the reading position is changed after the reading is interrupted. The first is to move backward and then move forward while vibrating again.
While controlling the movement of the reading position by the drive signal of
Movement control means for controlling the oscillation of the reading position with the drive signal and resetting the sampling signal at a predetermined reset timing according to the second drive signal; and a phase of the oscillation in the reading before and after the interruption of the reading. So that the phase of the vibration and the first
An image reading device comprising: a vibration phase control unit that controls a relationship with a driving signal of the image reading device. 4. The image reading device according to claim 3, wherein said movement control means controls said relationship by changing a frequency of said first drive signal based on control of said vibration phase control means. apparatus. 5. A thinning-out means for thinning out the read data obtained by the conversion means at a predetermined ratio with respect to the number of the sampling signals, and wherein the read position is set to the re-read start position from the predetermined reset timing. 5. The apparatus according to claim 3, further comprising timing management means for matching thinning timings by the thinning means before and after the interruption of the reading according to the number of the sampling signals generated until the signal passes. An image reading device according to claim 1. 6. The apparatus according to claim 1, wherein said movement control means generates said predetermined reset timing after the frequency of said first drive signal becomes constant. Image reading device. 7. A process for processing the read data, wherein the storage of the read data is performed, and when a predetermined amount of the read data is stored, at least the movement control unit is notified that the processing is disabled, and the read data is stored. 2. The apparatus according to claim 1, further comprising a buffer memory for stopping accumulation of data and transferring the accumulated data.
7. The image reading device according to any one of claims 1 to 6.