JPH09200433A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader which never spoils picture quality even at a start or stop time inexpensively without using complicated control. SOLUTION: The image reader having a read part which uses a stepping motor 6 as a driving source and uses a CCD 8 as an image read sensor counts the driving signal of the stepping motor 6 by a timing generator 9, outputs a read start pulse to the CCD 8 at every constant excitation number, and sends a fetching signal to the CCD 8 a certain time after the pulse is sent out.

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 facsimile having high reading accuracy.

[0002]

2. Description of the Related Art A conventional facsimile apparatus is roughly composed of a reading section, a recording section and a communication section. The structure of this reading unit is such that the position of the reading sensor is fixed assuming that a sheet original is read, and the original is fixed on the assumption that the sheet through type in which the original is conveyed using some conveyance means and the book original are read. There are two types of book types that move the sensor. Even in the case of the book scanner type reading system or the sheet through type reading system, the reading unit of the facsimile apparatus needs to perform intermittent driving unlike the reading units of other apparatuses. In this case, since the motor needs to be able to control the stop position, it is an essential condition to use some kind of synchronous motor as its drive source. For this reason,
In many cases, a stepping motor, which is cost-effective and relatively easy to control, is used as the drive system of the reading unit. When using a stepping motor as the drive source, in order to improve the start-stop accuracy, a slow-up of known technology,
Slow down control is often performed. Also, of course, it is essential to have some kind of optical reader,
A CCD sensor is often used because it involves photoelectric conversion. In this case, in the reading unit, the rotational drive amount of the motor (which is reflected in the original document movement amount in the sheet scanner type and the sensor movement amount in the book scanner type) is 1 of the CCD sensor.
It should be constant per reading time.
It is known that when the motor rotation drive amount per unit time is different, “fluctuation” occurs in the read image, which causes a serious problem in image quality. As an example, JP-A-60-
The "document reading device" described in Japanese Patent No. 100871 aims to prevent image deterioration at the start of document feeding, but when a drive source is a stepping motor, slow-up control peculiar to the drive source is performed. There is concern that the effects of this case may not be expected.

[0003]

The above-mentioned conventional technique has a problem that the image quality of the read image is deteriorated when the motor rotation driving amount per unit time in the reading unit is different. Further, the technique described in the above publication has a problem that when a stepping motor is used as a drive source, the effect of performing slow-up control peculiar to the drive source cannot be expected. An object of the present invention is to solve such problems,
An object of the present invention is to provide an image reading apparatus that does not impair the image quality even at the time of starting and stopping at low cost and without using complicated control. Another object of the present invention is to prevent the image reading apparatus from being affected by an electrical delay (electrical circuit delay, etc.) or being affected by a response delay of the stepping motor.

[0004]

In order to achieve the above object, the invention according to claim 1 is an image reading apparatus having a reading section which uses a stepping motor as a driving source and uses a CCD as an image reading sensor. It is characterized in that the drive signal (excitation control signal) of the motor is counted, a reading start pulse is output to the CCD for each constant number of excitations, and after the pulse is sent, a fetch signal is sent to the CCD after a fixed time. is there. According to a second aspect of the invention, in the image reading device, a comparator is provided in the constant current driver circuit, and a function of detecting a counter electromotive force by referring to a reference signal is provided. The counter electromotive force generation is counted, a reading start pulse is output to the CCD for every certain number of counts, and after the pulse is sent, the CCD is output for a certain time.
It is characterized in that it sends out a capture signal to. According to a third aspect of the present invention, in the image reading device, a circuit for counting the output of the encoder is provided, the encoder output pulse is counted, a reading start pulse is output to the CCD for every certain count number, and after the pulse is sent out. The feature is that the capture signal is sent to the CCD after a fixed time.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, drive data from a sequencer of a motor drive unit is also supplied to a timing generator. The timing generator, which has a built-in counter and timing circuit, measures the number of times the motor drive signal is input, sends a start signal to the CCD at every fixed number of excitations, and sends the start signal to the CCD after a lapse of a fixed time. Send the latch signal. The CCD reads one line in the sub-scanning direction between the transmission of the start signal and the transmission of the latch signal. Therefore, the degree of freedom of the motor drive sequence including the start and stop is improved, and the reading timing according to the motor drive sequence can be arbitrarily set. Alternatively, the reference resistance output in the motor driver is input to the comparator, and when the comparator detects a negative voltage value (generated by driving the stepping motor at the time of switching excitation during two-phase excitation), the detection signal is sent to the timing generator. Configure. The reading timing is generated by the comparator output data to avoid the influence of electrical circuit delay and the like. Alternatively, by mounting the encoder on the stepping motor, the timing generator generates the read timing based on the encoder output data,
Avoid the effect of stepping motor response delay.

An embodiment of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 2 is a diagram showing the overall construction of a facsimile apparatus according to the first embodiment of the present invention. The reading unit in this embodiment includes a reading scanning unit 12 and a reading processing unit 1.
6, a line memory 14, and a ramen memory control unit 18. The recording unit includes a recording scanning unit 13, a recording processing unit 17, a line memory 14, and a line memory control unit 18.
It consists of. Note that FIG. 2 shows a case of a full-duplex configuration.
The image information read by the reading scanning unit 12 is read by the reading processing unit 1.
After going through 6, the data is once stored in the line memory 14. Depending on the mode of the information compression / decompression unit 19, the line memory 14
Redundancy is removed while reading image information from
The data is stored again in the RAM 24 through the data / address bus 21. The RAM 24 is used as a transmission buffer, and again sent to the modem 15 via the communication control unit 20. The signal modulated by the modem 15 is sent out to the line through the network control unit 26. On the contrary, the image information received from the line passes through the network control unit 26, is demodulated by the modem 15, passes through the communication control unit 20, and passes through the data / address bus 21.
And is stored in the RAM 24. The RAM 24 is used as a reception buffer, and the information compression / decompression unit 1 is sequentially operated.
9 through the data / address bus 21.
The recording processing unit 1 is called again from the line memory 14.
After 7, the recording / scanning unit 13 reproduces the image information. The image information includes the network control unit 26 and the communication control unit 2.
Although it simply passes through 0, the communication control information is read and understood in the communication control unit 20 to perform execution processing such as transmission control and error control. When journal information is needed, it is non-volatile. It is stored in the RAM 24 having a function. The network control unit 26 controls call signals for network control. In addition, image information that does not require information compression and restoration is
Data / data can be directly read from the reading processing unit 16 and the line memory 14.
It is taken out to the outside such as the RAM 24 via the address bus 21, and image processing and image communication can be performed. In addition, the image-processed information or the image-synthesized information is directly input, or the image information is superposed on the line memory 14.
It is also possible to store and record and reproduce. The line memory 14 can be used separately from the information compression / decompression unit 19, and at the same time, the compressed information can be restored and output via the line memory 14 regardless of the reading scan and the recording scan. . The MPU 2 performs overall system control, information flow management, communication control, and network control. The main processing of system control is control related to the man-machine interface by the panel unit 27 and control related to the mechanical configuration of the reading unit and the recording unit by the mechanism control unit 3. The panel unit 27 greatly differs in the number of input / output terminals and the control method depending on the type and type of panel switch and panel display. Further, the mechanism control unit 30
The type and number of drivers and sensors vary depending on the system and mechanical configuration of the reading unit and recording unit, and this affects the complexity of control.

Next, the structure of the motor drive unit in this embodiment will be described with reference to FIG. The motor drive unit of this embodiment is
ROM storing drive data including motor drive table
1, a MPU 2, a mechanism control unit 30 (including a sequencer 3, a serial / parallel converter 4, and a motor driver 5) and a stepping motor 6. The output data of the sequencer 3 includes a reading unit (including the CCD 8 and the image processing unit 7).
It is also transmitted to the timing generator 9 which sets the reading timing of. This timing generator 9
Includes a counter for counting the number of times the motor drive signal is input, and a clock circuit.

The drive control of the motor drive unit and the reading unit is as shown in FIG. In the present embodiment, at the reading start timing, the MPU 2 reads the motor drive table determined in advance by the system from the ROM 1 and sends the drive data to the sequencer 3. The sequencer 3 generates excitation information (sequencer output data in FIG. 3) in the serial data format based on the drive data reference clock.
The serial / parallel converter 4 converts this data into phase excitation corresponding data (parallel data), and supplies an excitation instruction signal for each phase (serial / parallel converter output in FIG. 3) to the motor driver 5. The stepping motor 6 is drive-controlled by the drive current from the motor driver 5. On the other hand, the drive data from the sequencer 3 is also supplied to the timing generator 9. Timing generator 9
Measures the number of times the motor drive signal has been input by the counter, and sends a start signal to the CCD 8 at every constant number of excitations. Also, the timing generator 9
After sending the start signal, the timer circuit measures a certain time, and after a certain time elapses, a latch signal is sent to the CCD 8. The reading period of the CCD 8 for one line in the sub-scanning direction is from the start signal transmission to the latch signal transmission (accumulation period in FIG. 3). The present embodiment is an embodiment of the invention described in claim 1.

(Second Embodiment) In the first embodiment, the generation of the read timing is based on the motor excitation sequence signal (sequencer output data). In this case, there may be a slight deviation from the timing of the current applied in the motor due to an electrical circuit delay or the like. Therefore, an actual example for dealing with this will be shown. The overall structure of the apparatus is similar to that of the first embodiment (FIG. 2). FIG. 4 shows the configuration of the motor drive unit in the present embodiment, in which a comparator 41 is newly provided. The reference resistance output in the motor driver 5 is input to the comparator 41, and the comparator 41 is configured to detect a negative voltage value from this and send a detection signal to the timing generator 9. The ROM 1 stores drive data including a motor drive table as in the first embodiment, and the timing generator 9 includes a counter and a time counting circuit for measuring the number of times the detection signal is input from the comparator 41. Has been done.

The drive control of the motor drive unit and the reading unit is as shown in FIG. Also in the present embodiment, at the reading start timing, the MPU 2 reads the motor drive table determined in advance by the system from the ROM 1 and sends the drive data to the sequencer 3. Sequencer 3
Is excitation information in serial data format based on the drive data reference clock (sequencer output data shown in FIG. 3)
Generate The serial / parallel converter 4 converts this data into phase excitation corresponding data (parallel data) and supplies an excitation instruction signal (serial / parallel converter output shown in FIG. 3) for each phase to the motor driver 5. The stepping motor 6 is drive-controlled by the drive current from the motor driver 5. The above is the same as in the first embodiment. In this embodiment, the output of a reference resistor (not shown) in the motor driver 5 is input to the comparator 41, and the comparator 41 detects the back electromotive force (negative voltage) generated by driving the motor when switching the two-phase excitation. The voltage value across the reference resistor represents a waveform representative of the current waveform in the motor coil, and as shown in FIG.
A negative voltage value (hatched portion) is generated due to the driving of the stepping motor when switching the excitation during the phase excitation. When a negative voltage value is detected in this way, a detection signal (comparator output data in FIG. 5) is sent from the comparator 41 to the timing generator 9. The timing generator 9 measures the number of times the motor drive signal is input by the counter, and sends a start signal to the CCD 8 at every constant number of excitations. Also the timing generator 9
Measures a fixed time after the start signal is sent by the clock circuit, and sends a latch signal to the CCD 8 after the fixed time has elapsed. The reading period of the CCD 8 for one line in the sub-scanning direction is from the start signal transmission to the latch signal transmission (accumulation period in FIG. 5).

According to the present embodiment, the read timing is generated not by the sequencer output data but by the comparator output data. Therefore, it is possible to avoid the influence of electrical circuit delay and the like. The present embodiment shows an embodiment of the invention described in claim 2.

(Third Embodiment) In the first and second embodiments, the reading timing is generated by the motor excitation sequence signal (sequencer output data or comparator output data). In this method, it is possible that the motor drive display by the excitation sequence does not actually match the motor rotation amount. In this case, if the timing is generated only from the excitation sequence, it is conceivable that a problem will occur in image reading. Therefore, an actual example for dealing with this will be shown. The overall structure of the apparatus is similar to that of the first embodiment (FIG. 2). FIG. 7 shows the configuration of the motor drive unit according to the present embodiment.
1 is attached to the stepping motor 6. The encoder 71 is configured to detect the drive current of the stepping motor 6 and send a detection signal to the timing generator 9. Note that the ROM 1 stores drive data including a motor drive table as in the first embodiment, and the timing generator 9 includes an encoder 7
A counter for measuring the number of times the detection signal from 1 is input, and a clock circuit are incorporated.

The drive control of the motor drive unit and the reading unit is as shown in FIG. Also in the present embodiment, at the reading start timing, the MPU 2 reads the motor drive table determined in advance by the system from the ROM 1 and sends the drive data to the sequencer 3. Sequencer 3
Is excitation information in serial data format based on the drive data reference clock (sequencer output data shown in FIG. 3)
Generate The serial / parallel converter 4 converts this data into phase excitation corresponding data (parallel data) and supplies an excitation instruction signal (serial / parallel converter output shown in FIG. 3) for each phase to the motor driver 5. The stepping motor 6 is drive-controlled by the drive current from the motor driver 5. The above is the same as in the first embodiment. In the present embodiment, the detection signal (encoder output data in FIG. 8) of the encoder 71 mounted on the stepping motor 6 is
It is sent to the timing generator 9. The timing generator 9 measures the number of times the detection signal is input from the encoder 71 using the counter, and C
A start signal is sent to CD8. Further, the timing generator 9 sends out the start signal, then measures a fixed time by the clock circuit, and sends out a latch signal to the CCD 8 after the fixed time elapses. The reading period of the CCD 8 for one line in the sub-scanning direction is from the start signal transmission to the latch signal transmission (accumulation period in FIG. 8).

According to this embodiment, the read timing is generated not by the sequencer output data or the comparator output data but by the encoder output data mounted on the stepping motor. Therefore, even if the motor drive display according to the excitation sequence and the motor rotation amount do not actually match, they are not affected. The present embodiment shows an embodiment of the invention described in claim 3.

[0015]

According to the invention described in claim 1, the degree of freedom of the motor drive sequence including the start and stop can be improved. Further, the reading timing according to the motor drive sequence can be set arbitrarily, and the reading accuracy can be improved. Further, the setting labor at the time of design can be significantly reduced. According to the invention described in claim 2,
In addition to the above effects, the reading timing according to the motor drive sequence can be arbitrarily set without being affected by electrical delay. According to the invention described in claim 3,
In addition to the above effects, the reading timing according to the motor drive sequence can be arbitrarily set without being affected by the response delay of the motor.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a motor drive unit according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an overall configuration of a facsimile apparatus according to the first embodiment of the present invention.

FIG. 3 is a timing chart of a motor driving unit and a reading unit according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a motor drive unit according to a second embodiment of the present invention.

FIG. 5 is a timing chart of a motor driving unit and a reading unit according to the second embodiment of the present invention.

FIG. 6 is a diagram showing a waveform of an applied current in a motor during general constant current driving, which is used in the second embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of a motor drive unit according to a third embodiment of the present invention.

FIG. 8 is a timing chart of a motor driving unit and a reading unit according to a third embodiment of the present invention.

[Explanation of symbols]

1: ROM, 2: MPU, 3: sequencer, 4: serial / parallel converter, 5: motor driver, 6: stepping motor, 7: image processing unit, 8: CCD, 71: encoder.

Claims (3)

[Claims] 1. A CC using a stepping motor as a drive source.
In an image reading apparatus having a reading unit that uses D as a reading sensor, a counter and a timing circuit are built in, the driving signal of the stepping motor is counted, and a reading start pulse is output to a CCD for each constant number of excitations. An image reading apparatus comprising means for sending a reading signal to a CCD after a predetermined time has passed after sending a reading start pulse. 2. A stepping motor is used as a drive source and CC
In an image reading apparatus having a reading unit that uses D as a reading sensor, a constant current driver circuit for driving the stepping motor detects a counter electromotive force in a stepping motor coil by referring to a reference signal. , Providing a comparator for outputting a detection signal, incorporating a counter and a timing circuit, receiving the detection signal to count the number of occurrences of the counter electromotive force, and outputting a reading start pulse to the CCD for each constant count number, An image reading apparatus comprising means for sending a reading signal to a CCD after a predetermined time has passed after sending the reading start pulse. 3. A stepping motor is used as a drive source, and CC
In an image reading apparatus having a reading unit that uses D as a reading sensor, an encoder is attached to the stepping motor, a counter and a timing circuit are built in, the output pulse of the encoder is counted, and a CCD is counted at a constant count number. An image reading apparatus comprising means for outputting a reading start pulse to the CCD, and sending a reading signal to the CCD after a predetermined time after sending the reading start pulse.