JPH08293969A - Image reader - Google Patents

Abstract

PURPOSE: To prevent runaway or damage even when any abnormality is generated in the control program of a drive motor by counting the number of phase excited pulse signals from the reading start of an original to the reading end of the original and stopping a power source to be supplied to the drive motor when that count value exceeds a reference value. CONSTITUTION: A CPU 20 outputs the phase excited pulse signal corresponding to rotating direction and speed to a motor driver part 23 and corresponding to this signal, the motor driver part 23 drives a drive motor 9. A count part 25 counts the number of phase excited pulse signals outputted from the CPU 20 from the reading start of the original. A comparing part 26 compares the value counted by the count part 25 with the reference value corresponding to the total number of phase excited pulse signals at the time of normal operation required for moving a carriage in series of original reading processes. When an Hi signal corresponding to the time of abnormal operation is outputted from the comparing part 26, a motor main power source control part 27 cuts off a main power source 24 to the drive motor 9.

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 of the type in which an image is read while a carriage moves in a sub scanning direction.

[0002]

2. Description of the Related Art In recent years, workstations, personal computers, and the like have been made highly functional, and full-color images can be edited and images can be input at high speed by electronic filing. Along with this, flatbed type scanners have become widespread as image reading devices that can easily input images.

The structure and operation of a conventional scanner will be described below. FIG. 5 is a schematic diagram showing the configuration of a conventional flatbed type scanner 200. FIG.
It is a schematic diagram showing the composition of the optical system of this conventional scanner 200. FIG. 7 is a block diagram showing the configuration of the signal processing unit of the conventional scanner 200.

As shown in FIG. 5, this scanner 200
Includes a document glass 2, a carriage 3, a support member 4, a shaft 5, a drive wire 6, and
A drive pulley 7, a driven pulley 8, a drive motor 9, a driven pulley support member 10, and a biasing portion 11 are provided. The original glass 2 is a portion on which a user sets an original. The carriage 3 is a part that reads an image from a set original. The support member 4 has a bearing or the like inside and supports the carriage 3. The shaft 5 supports the carriage 3 via the support member 4. The shaft 5 restricts the movement of the carriage 3 only in the sub-scanning direction. The drive motor 9 is a stepping motor for driving the carriage 3. Drive motor 9
The rotational driving force of the drive shaft is transmitted from the drive pulley 7 to the drive wire 6 via a connecting shaft and a reduction mechanism (not shown), and the drive wire 6 rotates when the drive motor 9 rotates.
It moves in the left-right direction in FIG. 5 (hereinafter, referred to as “sub-scanning direction”). The movement of the drive wire 6 drives the carriage 3 in the sub-scanning direction. Further, the driven pulley 8 is
As shown in FIG.
Is applied to the drive wire 6 to apply tension to the drive wire 6.

An optical system and a color image sensor 15 are provided inside the carriage 3. This optical system
As shown in FIG. 6, the light source lamp 12 is provided in the carriage 3.
The document reading unit 13, the reflection mirror 14, and the image forming lens 16 are provided. Light source lamp 12 above
Illuminates the original placed on the original glass 2 from below.
The document reading unit 13 reads characters and images written on the document from the reflected light from the illuminated document. Reflection mirror 1
Reference numeral 4 reflects the reflected light from the document. Imaging lens 16
Causes the reflected light to form an image on the color image sensor 15. The color image sensor 15 converts an incident light signal into an electric signal.

The above-described conventional scanner 200 has an image signal processing mechanism for processing the image signal output from the color image sensor 15 and a motor drive control mechanism which is a motor drive control means for controlling the drive of the drive motor 9. ing. Two
Reference numeral 4 is a main power source for the drive motor 9. As shown in FIG. 7, the image signal processing mechanism includes an A / D conversion unit 17, an image processing unit 18, a buffer memory 19, a CPU 20, and an SC.
It is configured to include the SI controller 21. The A / D converter 17 converts the output (analog value) from the color image sensor 15 into a digital signal. The image processing unit 18 subjects the digital data input from the A / D conversion unit 17 to image processing such as shading, color correction, and resolution change. The buffer memory 19 temporarily holds the image data processed by the image processing unit 18. The SCSI controller 21 uses the buffer memory 19
Image data stored in the external host device 22.
Output to. The CPU 20 sets the processing mode of the image processing unit 18, initializes the buffer memory 19, and the like. Further, the motor drive control mechanism includes a motor driver unit 23,
It is configured to have a CPU 20. The motor driver unit 23 controls the drive motor 9 by PWM (PWM: Pulse).
It is controlled and driven by a constant current chopper method by Width Modulation). The CPU 20 has a motor driver unit 23.
To the drive motor phase excitation pulse signal. In the above, the color image sensor 15 in the carriage 3
And a drive motor 9 for driving the carriage 3 in the sub scanning direction.
And a carriage drive mechanism such as a drive wire 6, an A / D converter 17, an image processor 18, a buffer memory 19, and a CPU.
The image signal processing mechanism including 20 and the like constitutes an image reading means.

The operation of the conventional scanner 200 configured as above will be described below. When the external host device 22 outputs a document reading start signal to the CPU 20, the CPU 20 outputs a phase excitation pulse signal corresponding to the rotation direction (phase excitation sequence) and speed (frequency) to the motor driver unit 23. The motor driver 23 drives the drive motor 9 to rotate in response to the phase excitation pulse signal. The rotational driving force of the drive motor 9 is transmitted to the carriage 3 via the drive pulley 7, the drive wire 6, and the driven pulley 8, and the carriage 3 starts scanning in the sub scanning direction. At the same time, the CPU 20 turns on the light source lamp 12 to illuminate the document. The reflected light from the original is reflected by the reflection mirror 1.
It is reflected by 4, and is imaged on the color image sensor 15 by the imaging lens 16 and converted into an electric signal.

Since the drive motor 9 rotates by a rotation angle proportional to the number of phase excitation pulse signals output from the CPU 20 to the motor driver section 23, the moving distance of the carriage 3 is output from the CPU 20 to the motor driver section 23. It can be controlled by the total number of phase excitation pulse signals.
In this way, the number of phase excitation pulse signals corresponding to the scanning distance in the sub-scanning direction is output from the CPU 20 to the motor driver unit 23. With this phase excitation pulse signal,
The motor driver unit 23 drives the drive motor 9. The carriage 3 is scanned in the sub-scanning direction by the driving force of the drive motor 9, and the reading of the document is completed. When the reading of the document is completed, the CPU 20 outputs a phase excitation pulse signal in which the rotation direction of the drive motor 9 is reversed to the motor driver unit 23. The reverse phase excitation pulse signal causes the carriage 3 to return to the original reading start position through a process reverse to the above original reading. When the series of document reading processes are completed, the CPU 20 outputs a document reading completion signal to the external host device 22.

[0009]

However, the above-mentioned conventional scanner has the following problems. That is, the control program for controlling the drive of the drive motor 9 used to drive the carriage 3 runs away and the CPU
If the phase excitation pulse signal continues to be output from the motor driver unit 23 to the motor driver unit 23, the drive control of the drive motor 9 cannot be performed, and as a result, the carriage 3 runs out of the reading range and collides with the end of the apparatus. If the drive motor 9 is excited in that direction even after the collision, there is a risk that the drive motor 9 will be damaged by heating.

The present invention has been made to solve the above problems, and provides an image reading apparatus capable of preventing runaway or damage of a drive motor even when an abnormality occurs in a control program of the drive motor. The purpose is to

[0011]

In order to solve the above problems, an image reading apparatus according to the present invention comprises a light source for illuminating a document, an optical system for forming reflected light or transmitted light from the document, and an image formation. An image reading device having image reading means for reading the image of the original document, comprising: a drive motor for scanning the image reading means; a main power supply for the motor for supplying power to the drive motor; and a phase excitation for the drive motor. Motor drive control means for driving and controlling the drive motor by outputting a pulse signal, counting means for counting the number of the phase excitation pulse signals from the start of reading by the image reading means, and a reference value Comparing means for comparing the count value from the counting means with the reference value, and ON / O of the motor main power supply according to the output from the comparing means.
A motor main power supply control means for performing FF control, wherein the motor main power supply control means transfers the motor main power supply to the drive motor when the count value from the counting means exceeds the reference value. It is configured to shut off the supplied power.

[0012]

According to the image reading apparatus of the present invention having the above structure, the counting means counts the number of phase excitation pulse signals from the start of reading the original to the end of reading the original. The comparing means operates normally (count value <
For example, the Lo signal is output in the case of the reference value, and the Hi signal is output in the abnormal operation (when the count value> the reference value). The motor main power supply control means controls ON / OFF of the motor main power supply according to the output from the comparison means, but when the count value from the count means exceeds the reference value (for example, the output of the comparison means is a Hi signal). In this case), the power supply from the motor main power supply to the drive motor is cut off.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of a portion that controls a scanner 100 that is an embodiment of the present invention. Further, FIG. 2 is a block diagram showing a more detailed configuration of a portion that controls the scanner 100. Also, FIG.
FIG. 4 is a timing chart diagram (during normal operation) showing a signal waveform in each part of the scanner 100, and FIG. 4 is a timing chart diagram (during abnormal operation) showing a signal waveform in each part of the scanner 100. The configuration of the other mechanism of the scanner 100 is the same as that of the conventional scanner 200 shown in FIGS. 5 to 7, and the description thereof will be omitted.

As shown in FIG. 1, this scanner 100
However, the difference from the conventional scanner 200 shown in FIG. 7 is that
The point is that a counting unit 25 that is a counting unit, a comparison unit 26 that is a comparing unit, and a motor main power source control unit 27 that is a motor main power source control unit are newly provided. The counting unit 25 is connected to the CPU 20 and counts the number of phase excitation pulse signals output from the CPU 20 to the motor driver unit 23 from the start of reading the original. The comparison unit 26 is connected to the output side of the counting unit 25, and is a reference value for the total number of phase excitation pulse signals during normal operation required for the carriage 3 to move during a series of document reading processes, and the count counted by the counting unit 25. Compare with the value. Further, the motor main power supply control unit 27 is connected to the output side of the comparison unit 26 and in the middle between the motor main power supply 24 and the drive motor 9, and the comparison unit 26
When the Hi signal corresponding to the abnormal operation is output from, the main motor power supply to the drive motor 9 is shut off.

During normal operation of the scanner, the count value of the number of phase excitation pulse signals counted by the counting unit 25 is started until the CPU 20 outputs the document reading end signal when the reading of the document is started. It is set so as not to exceed the reference value in the comparison unit 26. In this case, since the comparison unit 26 outputs the Lo signal to the motor main power supply control unit 27, the motor main power supply control unit 27 supplies the drive motor 9 with the main power supply while keeping the motor main power supply 24 in the ON state. To be done.

On the other hand, the CPU 20 starts reading the original document.
If the count value of the number of phase excitation pulse signals counted by the counting unit 25 exceeds the reference value in the comparing unit 26 (during abnormal operation) before the output of the reading end signal of the document, the comparison is performed. The section 26 is a main power source control section 27 for the motor.
Since the Hi signal is output to the
Shuts off the motor main power supply 24 supplied to the drive motor 9, and the drive motor 9 stops driving.

As shown in FIG. 2, the counting unit 25 that counts the number of phase excitation pulse signals output from the CPU 20 has a counter 30. The comparison unit 26 includes an AND gate 32 corresponding to the reference value, flip-flops 33 and 34, and an inverter 31. The motor main power supply controller 27 is configured to include transistors 35 and 36.

Further, as shown in FIG. 2, the reading start signal / end signal of the document output by the CPU 20 is the counter 3
0 and the reset signal S1 for resetting the flip-flops 33 and 34. This reset signal S
By 1, each is reset at the start / end of reading the original.

Further, the scanner 100 of the present embodiment is provided with a home position sensor 29 at the home position of the carriage 3, and is configured to output a reset signal S1 when the carriage 3 comes to the home position. .
As a result, the counter 30 and the flip-flops 33 and 34 are reset when the carriage 3 reaches the home position.

Next, with reference to FIG. 3, the operation of each part in FIG. 2 during normal operation in which the motor control program does not run away will be described. First, when the CPU 20 outputs a reset signal in response to a read start signal output from the external host device 22 or the home position sensor 29 outputs a reset signal, the counter 30 and the flip-flops 33 and 34 are reset. Done.

At the same time when the reset signal is output, the CPU 2
A phase excitation pulse signal is output from 0. This allows
The excitation / drive of the drive motor 9 is started. At the same time, the counter 30 starts counting the number of phase excitation pulse signals, and the pulse number count value is output to each output bit C0, C1, ..., Cn (see the signal in FIG. 3).

The AND gate 32 is provided with a reference value for the number of excitation pulse signals in the normal operation required for the movement of the carriage 3 in a series of document reading processes. Therefore, the output of the AND gate 32 becomes Hi only when the pulse count values C0, C1, ..., Cn match the reference value. On the other hand, during normal operation, the pulse count value does not exceed the reference value, so the output of Lo is maintained (see the signal in FIG. 3).

At the D1 terminal of the flip-flop 33, A
The output of the ND gate 32 is input. The clock terminal receives a reverse phase signal obtained by reversely converting the phase excitation pulse signal of the drive motor 9 by the inverter 31 in consideration of the time delay of the signal. This allows AND for each count
The output value of the gate 32 is output from Q1. During normal operation, the pulse number count value counted by the counter 30 does not match the reference value of the AND gate 32. Therefore, the output from the AND gate 32 is Lo
Q1 also maintains Lo (see the signal in FIG. 3).

The D2 terminal of the flip-flop 34 is +
5V (Hi) is input. The output Q1 of the flip-flop 33 is input to the clock terminal. During normal operation, the clock Q1 maintains Lo, so the output Q2 of the flip-flop 34 is L at reset.
It does not change from the o level (see the signal in FIG. 3). Thus, during normal operation, the output Q2 from the comparison unit 26
Keeps Lo.

In this normal operation, the output Q2 of the flip-flop 34 is at the Lo level as described above, so in the motor main power ON / OFF control unit 27, the transistor 35 is turned off and the transistor 36 is turned on.
It becomes a state. Therefore, the drive motor 9 is supplied with power from the motor main power supply 24 (see the signal in FIG. 3).

Next, with reference to FIG. 4, the operation of each part in FIG. 2 at the time of abnormal operation in which the motor control program has run away will be described. First, the CPU 20 or the home position sensor 29 outputs a reset signal in response to a read start signal output from the external host device 22, and the counter 30 and the flip-flops 33 and 34 are reset.

At the same time, the CPU 20 outputs a phase excitation pulse signal to start excitation / driving of the drive motor 9, and the counter 30 starts counting the number of phase excitation pulse signals to output the output bits C0, C1, ..., Cn. The pulse count value is output to (see the signal in FIG. 4).

At the time of abnormal operation, the pulse number count value C0
, C1, ..., Cn exceed the reference value of the AND gate 32, the timing at which the count values C0, C1, ..., Cn coincide with the reference value occurs, and the output of the AND gate 32 also becomes Hi at that timing. (See the signal in FIG. 4).

At the D1 terminal of the flip-flop 33, A
The output of the ND gate 32 is input. AND gate 32
When the output of H becomes Hi, the Hi signal is output from the output Q1 in synchronization with the clock (see the signal of FIG. 4).

When the output Q1 of the flip-flop 33 becomes Hi, the output Q2 of the flip-flop 34 changes from Lo level to Hi level in synchronization with it (see the signal in FIG. 4). Thus, during abnormal operation, the output Q2 from the comparison unit 26 becomes Hi level, and does not become Lo level until the reset signal is input again from the CPU 20 or the home position sensor 29.

During this abnormal operation, the output Q2 of the flip-flop 34 is at the Hi level as described above, so that in the motor main power source control section 27, the transistor 35 is turned on.
The N state is set and the transistor 36 is turned off.
Therefore, the motor main power supply 2 supplied to the drive motor 9
The power from the power supply 4 is cut off, and the drive of the drive motor 9 is stopped (see the signal in FIG. 4).

[0032]

As described above, according to the present invention,
Even when the control program of the drive control means for controlling the drive of the drive motor runs away and the phase excitation pulse signal continues to be output from the drive control means to the drive motor, the motor main power supply control means controls the drive motor. Since the power supply is cut off, the drive motor is surely stopped, the carriage of the image reading means is prevented from running away, and the carriage or the like may be collided with any one end in the image reading device and damaged. To be prevented.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a part that controls a scanner according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a more detailed configuration of a part that controls the scanner shown in FIG.

3 is a timing chart showing signal waveforms at various parts of the scanner shown in FIG. 2 (during normal operation).

4 is a timing chart showing signal waveforms at various parts of the scanner shown in FIG. 2 (during abnormal operation).

FIG. 5 is a schematic diagram showing the configuration of a conventional scanner.

FIG. 6 is a schematic diagram showing a configuration of an optical system of the conventional scanner shown in FIG.

7 is a block diagram showing a configuration of a signal processing unit of the conventional scanner shown in FIG.

[Explanation of symbols]

 1 Scanner Main Body 2 Original Glass 3 Carriage 4 Support Member 5 Shaft 6 Drive Wire 7 Drive Pulley 8 Driven Pulley 9 Drive Motor 10 Driven Pulley Supporting Member 11 Energizing Part 12 Light Source Lamp 13 Original Reading Part 14 Reflection Mirror 15 Color Image Sensor 16 Connection Image lens 17 A / D conversion unit 18 Image processing unit 19 Buffer memory 20 CPU 21 SCSI controller 22 External host device 23 Motor driver unit 24 Motor main power supply 25 Counting unit 26 Comparison unit 27 Motor main power supply control unit 29 Home position sensor 30 counter 31 inverter 32 AND gate 33, 34 flip-flop 35, 36 transistor 37 resistor 100, 200 scanner S1 reset signal

Claims (1)

[Claims] 1. An image reading apparatus comprising a light source for illuminating an original, an optical system for forming reflected light or transmitted light from the original, and image reading means for reading the formed original image. A drive motor for scanning the means, a motor main power supply for supplying power to the drive motor, and a motor drive control means for driving and controlling the drive motor by outputting a phase excitation pulse signal to the drive motor, Counting means for counting the number of the phase excitation pulse signals from the start of reading by the image reading means, comparison means for having a reference value and comparing the count value from the counting means with the reference value, and the comparison Motor main power supply control means for controlling ON / OFF of the motor main power supply according to an output from the means, the motor main power supply control means being the counting means. When the count value of et exceeds the reference value, the image reading apparatus characterized by interrupting the power supplied to the drive motor from the motor main power.