JPH05153336A - Picture reader - Google Patents

Abstract

PURPOSE:To prevent occurrence of a deviation in the position control due to the direction of the movement of a read means by detecting a reference marker in the forward and the reverse process of reciprocating movement of the read means and calculating a pulse correction count of a drive source so as to implement correction. CONSTITUTION:A CCD line sensor 9 is placed at a standby position and a stepping motor 14 is driven forward by one step via a motor drive circuit 38 and a counter 35e is incremented. A senior 9 reads the picture by one line and a CPU 30 is used to obtain digital picture data from the picture data through an amplifier 42, an A/D converter 43 and a processing circuit 44. The sensor 9 detects a reference marker 20 and drive pulse number N1 of the motor 14 required for the movement is stored in a storage section 35b of a RAM 35. Similarly, the sensor 9 is moved backward to detect the marker and drive pulse number N2 of the motor 14 required for the movement is stored in a storage section 35c of the RAM 35. A pulse correction value of the motor 14 is calculated for the correction based on the numbers N1 and N2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus for reading an original while moving the reading means relative to the original holding means in the front-back direction and in the sub-scanning direction.

[0002]

2. Description of the Related Art A conventional image reading apparatus is an image reading apparatus which reads a document while moving the reading unit by a predetermined amount in the sub-scanning direction with respect to the document held by a document holding unit. From the time when the means is located at the standby position, the count value of the counting means for increasing or decreasing the count value according to the forward movement and the backward movement for each drive of the unit driving amount of the stepping motor for moving the reading means, and the sub-scanning of the document holding means. The position of the reading means based on the stored value of the storage means that stores the count value of the counting means when the reading means detects the reference marker provided outside the reading area in the direction, The image reading apparatus is configured such that the reading is started from the reading start position or the reading end position designated by the reading command and the reading is ended at the reading end position or the reading start position.

[0003]

However, in such a conventional image reading apparatus, the reading means is moved in the forward direction, and the reading means detects the reference marker in the forward movement process. Since the position of the reading unit is managed with reference to the count value of the counting unit, the reading unit can be used when reading the document while moving the reading unit in the forward direction and when reading the document while moving the backward unit. The position of the reading unit is managed by the deviation of the driving amount of the stepping motor and the moving amount of the reading unit (moving position) depending on the moving direction due to the play of the moving mechanism (such as gear backlash) for moving the unit, that is, hysteresis. The data to be read and the actual position of the reading means do not match during the backward movement of the reading means, and the reading area shifts between the forward and backward reading operations. Would be no, not be good reading accuracy. Further, in order to eliminate this problem, it is necessary to precisely process the components of the moving mechanism in order to minimize the play of the moving mechanism of the reading means, which makes the moving mechanism expensive.

Therefore, the present invention provides a position control means that does not cause a deviation in the position control of the reading means depending on the direction of movement of the reading means in the forward and backward directions even if the moving mechanism has play. An object is to provide an image reading apparatus provided with the image reading apparatus.

[0005]

Therefore, in the image reading apparatus of the present invention, the reading means is relatively moved in the sub-scanning direction with respect to the original holding means for holding the original, and one line is moved every predetermined moving amount. An image reading device for reading a minute, a driving unit for moving the reading unit via a moving mechanism,
It has counting means for increasing or decreasing the count value from the standby position according to the unit driving amount of the driving means according to the driving direction, and a reference marker provided outside the reading area of the document holding means in the sub-scanning direction. , Storing the count value of the counting means when the reference means detects the reference marker during its movement, based on the stored count value and the count value of the counting means,
From the designated reading start position designated by moving the reading unit forward by controlling the relative position of the reading unit with respect to the document holding unit during the movement process, and from the designated reading end position designated by moving the reading unit backward. In the image reading apparatus that performs the reading operation of each of the originals, the count value from the standby position of the counting unit when the driving unit is driven forward and the reading unit detects the reference marker in the process of forward movement. A means for reading N1, and a means for driving the driving means in a backward direction to read a count value N2 from the standby position of the counting means when the reading means detects the reference marker in the course of backward movement. , The count value N1,
Means for calculating a correction value N from N2, and the count value N1,
A storage unit that stores at least two of N2 and the correction value N as management data, and based on the count value of the counting unit and the management data of the storage unit after the reading operation of the reading unit in the backward movement is completed, The drive amount of the drive unit is determined with the count value N1 as a reference, and the drive unit is moved forward by a drive amount corresponding to at least the correction value N to move the read unit to a read start designated position. A forward reading control means for continuously driving the driving means to perform a forward reading operation;
After the reading operation of the reading unit in the forward movement is completed, the driving amount of the driving unit is determined based on the count value of the counting unit and the management data of the storage unit, and the driving amount of the driving unit is determined. By moving the reading unit to the reading end designated position by driving at least the driving amount backward corresponding to the correction value N,
It is characterized by further comprising reverse drive control means for driving the drive means in reverse to perform a read operation in a reverse direction.

[0006]

With this structure, before starting the reading operation from the reading start designated position or the reading end designated position, the driving means is driven in the same direction as that of the reading operation by the driving amount corresponding to the correction value. The reading start designated position and the reading end designated position based on the count value N1 or N2 of the counting means when the reading means detects the reference marker when the reading means is moved in the same direction as the reading operation. Therefore, at the start of the reading operation, the hysteresis is eliminated, the reading means is moved in a faithful manner in accordance with the drive amount of the driving means, and the position of the reading means obtained based on the management data, The actual position of the reading means coincides with each other during both reciprocating movements.

Therefore, the reading area designated by both the forward movement reading operation and the backward movement reading operation can be accurately read.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a configuration diagram of a main part of the image reading apparatus viewed from the side,
FIG. 3 is a configuration diagram of a main part as viewed from the top. A rectangular window 2 is formed substantially in the center of the upper surface of the image reading apparatus main body 1, and a transparent glass plate 3 is fitted into the window 2 and surrounded by a reading area 4 (a, b, c, d) on which an original is placed. Area) is formed. A widthwise ruler 5 and a lengthwise ruler 6 are attached to the outside of the reading area 4 along one side and one side of the reading area 4, respectively.
Then, the original document 8 is attached to the original document alignment marker 7 provided in the vicinity of the contact portion between the width direction ruler 5 and the length direction ruler 6.
The original 8 is placed on the glass plate 4 with the image recording surface of the original 8 facing down.

A CCD line sensor 9 which is a reading means in which a reduced CCD (solid-state image sensor) is arranged in the width direction of the window 2 inside the main body 1, and the CCD line sensor 9
Light source 10 made of a fluorescent lamp provided in parallel to the CCD arrangement direction, and original 8 emitted from this light source 10.
A line sensor unit 12 is provided in which a unit is formed of an optical lens 11 for forming an image of the light reflected by the CCD line sensor 9. The line sensor unit 12 is reciprocated in the sub-scanning direction by driving the stepping motor 14 (driving means) via the moving mechanism 13. The moving mechanism 13 winds an endless belt 15, a part of which is fixed to the bottom portion of the line sensor unit 12, around pulleys 16 and 16 and stretches the belt 15, and one pulley 16 is driven by a stepping motor 14 (driving means). ) Driven by a motor gear 17 and a gear 18, and further guides the movement of the line sensor unit 12.
It is composed of 9.

On the back surface of the widthwise ruler 5, the C
A reference marker 20 serving as a reference position for determining the original reading start position X by the CD line sensor 9, that is, the starting position of the reading area 4, is printed on a white background in a line shape extending in the black main scanning direction. Further, a limit switch 21 for positioning the CCD line sensor 9 at a position farther from the reading area 4 than the position of the reference marker 20 is provided inside the main body 1. The limit switch 21 is turned on when the line sensor unit 12 pushes the limit switch 21, and its position is the CCD.
This is the standby position for the line sensor 9.

In FIG. 2, reference numeral 22 denotes an original pressing plate for fixing the original 8 placed on the glass plate 3 on the glass plate 3, and together with the glass plate 3 constitutes an original holding means. The document pressing plate 22 is configured to be rotatable by an opening / closing mechanism 23 shown in FIG. 4 with one end as a fulcrum. The opening / closing mechanism 23 will be described in more detail. As shown in FIG. 4A, a holding portion 26 of the document pressing plate 22 is attached to a shaft 25 incorporated in left and right frames 24 (only one frame is shown in the figure) of the main body. Is rotatably held, an opening spring 27 is inserted into the shaft 25, one end 27a thereof presses the original pressing plate 22, and the other end 27b thereof is fixed through the frame 24. The portion (the other end 27b) of the opening spring 27 protruding from the frame 24 is engaged with the grooves 28, 28 provided in the holding portion 26 of the document pressing plate 22 as shown in FIGS. Then, the document pressing plate 22 is positioned at the closed position and the open position. With this configuration, the document pressing plate 22 can be lightly opened by the opening spring 27 and can be reliably positioned between the closed position (FIG. 4B) and the open position (FIG. 4C). Further, since the positioning mechanism is performed by the other end 27b of the opening spring 27, the number of parts can be reduced.

FIG. 1 is a block diagram showing the electrical hardware configuration of the image reading apparatus. As shown in the figure, a CPU (central processing unit) 30 constituting the control unit main body is provided with a ROM (read only memory) 34, a RAM via an address bus 31, a data bus 32 and a control bus 33.
A (random access memory) 35, a DMAC (direct memory access controller) 36 and an external interface 37 are connected.

A motor drive circuit 38 for controlling step drive of the stepping motor 14 and the light source 10 are also provided.
Light source driving circuit 39 for controlling the lighting operation of the CCD line sensor 9 and CCD driving circuit 4 for controlling the reading operation of the CCD line sensor 9
0 and the limit switch 21 is the I / O port 41
It is connected to the CPU 30 via.

The output end of the CCD line sensor 9 is connected to the data bus 32 via an amplifier 42, an A / D converter 43, and a digital processing circuit 44, and is output by the photoelectric conversion action of the CCD line sensor 9. The analog image data is amplified by the amplifier 42, and the A / D converter 4
3 is digitally converted, and a digital signal is processed by a digital processing circuit 44. Then, the CPU 30 reads from the data bus 32 as digital image data,
It is designed to be stored in the AM 35.

The DMAC 36 controls the address in place of the CPU 30 when sending the image data stored in the RAM 35 to a host device (not shown) through the external interface 37.

The RAM 35 has an image data buffer 35a for temporarily storing image data, and a reference position data storage unit 35 for storing forward direction reference position data (N1) of the stepping motor 14, which will be described later.
b, a reference position data storage unit 35c that stores reverse direction reference position data (N2), a correction value storage unit 35d that stores a correction value N calculated from N1 and N2, and the number of drive pulses of the stepping motor 15 is counted. Counter 35e
(Counting means) and a read command storage section 35f for storing a read command sent from a host (not shown) are formed.

Any two of the reference position data storage section 35b, the reference position data storage section 35c, and the correction value storage section 35d store management data including two of N1, N2, and N. Is.

When the CPU 30 is powered on or receives a document reading command from a host device (not shown) via the external interface 37, the CPU 30 in the ROM 34 executes the control shown in FIG. It is set by the program.

Explaining this control, first, RA
For example, the contents of a temporary storage unit such as the image data buffer 35a in M35 is cleared and initialized (ST100),
The limit switch 21 is checked to determine whether the CCD line sensor 9 is located at the standby position. If not, the stepping motor 14 is detected via the motor drive circuit 38 and the limit switch 21 detects the line sensor unit 12. Drive until the CCD line sensor 9
To the standby position (ST101).

Next, the motor drive circuit 38 is instructed in the direction A to supply one pulse to drive the stepping motor 14 for one step to move the line sensor unit 12 in the direction A shown in FIG. Increment (ST102). During this movement, the CCD line sensor 9 reads an image for one line, and the CPU 3 digitizes the read analog image data through the amplifier 42, the A / D converter 43, and the digital processing circuit 44. Read image data (ST10
3).

Then, it is judged whether or not the reference marker 20 is detected by the CCD line sensor 9 (ST.
104). If not detected, the above ST10
2, the process of ST103 is repeated until it is detected.

When it is judged in ST104 that the reference marker 20 is detected, the count value of the counter 35e, that is, the line sensor unit 12 moves forward from the standby position and reaches the reference marker 20 in the process of forward movement. In this case, the number of drive pulses of the stepping motor 14 required to move to the reference marker 20 is used as the forward direction reference position data N1 and the reference position data storage unit 3 of the RAM 35 is used.
It is stored in 5b (ST105). Next, the motor drive circuit 3
8 is directed to the A direction and a predetermined pulse (10 pulses) is supplied to drive the stepping motor 14 to move the line sensor unit 12 forward in the A direction by 10 pulses, and the count value of the counter is incremented by 10. Do (ST
106).

Next, the motor drive circuit 38 is instructed in the B direction to supply one pulse to drive the stepping motor 14 to one.
The line sensor unit 12 is driven backward by B steps and the counter 35e is decremented (ST107).

During this movement, the CCD line sensor 9 is set to 1
The image for the line is read, and the CPU 30 reads the image data in which the read analog image data is digitized through the amplifier 42, the A / D converter 43, and the digital processing circuit 44 (ST108).

At this time, it is judged whether or not the reference marker 20 is detected by the CCD line sensor 9. If not detected, ST107 and ST108 are repeated until the reference marker 20 is detected, and ST1
If it is determined that it is detected in 09, the counter 3
The count value of 5e, that is, the number of drive pulses of the stepping motor 14 required for the line sensor unit 12 to move from the standby position to the reference marker 20 (when it reaches the reference marker 20 in the process of backward movement) is the backward reference position. Data N
2 is stored in the reference position data storage section 35c of the RAM 35 (ST110).

Then, the correction value N is calculated from the forward traveling direction reference position data N1 and the backward traveling direction reference position data N2, and the RAM is calculated.
The data is stored in the correction data storage unit 35d of 35 (ST11
1). The N is obtained by subtracting N2 from N1.

By the above processing, the actual position of the CCD line sensor 9 when the stepping motor 14 is driven in the A direction or the B direction by a predetermined number of pulses during the reading operation is the count value of the counter 35e at that time, N1 or From N2, it is managed as the actual position of the CCD line sensor 9 from the reference marker 20 in the moving process in the A direction or the moving process in the B direction, and the hysteresis of the moving mechanism is set to 1 of the stepping motor 14. The CCD line sensor 9 is corrected in units of the movement amount of the CCD line sensor 9 corresponding to the step, that is, the CCD line sensor 9 in the forward direction and the backward direction.
It is possible to accurately manage the position error of 1 by the amount equivalent to one step of the maximum stepping motor 14.

In the above, ST102 to ST105 are means for reading the count value N1 of the counting means, and ST107 to ST.
110 is a means for reading the count value N2 of the counting means, ST11
Reference numeral 1 is a means for calculating the correction value N.

Next, the actual reading process will be described. When a read command is input, the read command is stored in the read command storage unit 35f in the RAM 35 (ST112), the line sensor unit 12 is driven by the stepping motor 14 to move in the A direction, and the counter 35e is also operated.
Is incremented at the position indicated by the reading start designated position data of the reading command (actually, from the counted value of the counter 35e, the forward direction reference position data N1 and the reference marker 20 to the reading area 4).
(A value obtained by subtracting the number of steps corresponding to the start position X) reaches a predetermined number of pulses from that position to the motor drive circuit 32 to drive the step pig motor 14 in a predetermined step, for example, 4 steps, Each time step driving is performed, the CCD line sensor 9 is driven through the CCD driving circuit 40 to start image reading for one line (ST113), and the line sensor unit 12 is started.
, Image data buffer 35a for image data, image reading for one line, increment of counter 35e
Is repeatedly stored up to the reading end position, and when the position of the CCD line sensor 9 indicated by the count value of the counter 35e reaches the numerical value of the reading end designated position data of the reading command, the process of this reading operation (ST114) is performed. The execution is ended (ST115), and the next read command is input (ST11).
6).

When the next read command is input, this read command is stored in the read command storage section 35f in the RAM 35, and the stepping motor 14 is driven to move the line sensor unit 12 in the A direction or B direction. At the same time, the counter 35e is incremented or decremented so that the position of the CCD line sensor 9 (in this case A
The stepping motor 14 is driven to move the line sensor unit 12 until the count value of the counting means is determined based on the forward direction reference position data N1 in both the directions B and B (ST117). Then, from that position, the stepping motor 14 is driven in the B direction by the correction value N steps. In this drive, the counter 3
The counting process of 5e is not performed (ST118).

By the processing of ST118, the hysteresis of N steps is corrected, and the line sensor unit 12 moves faithfully with respect to the subsequent driving of the stepping motor 14 in the B direction and the counter 35e.
Since the count value of is corrected by N steps, which is equal to the correction value, the position of the CCD line sensor 9 when the stepping motor 14 is driven in the B direction thereafter is determined by the counter 3.
The position is obtained based on the count value of 5e and the backward-direction reference position data N2.

Then, the image reading operation is started from that position (ST119), the line sensor unit 12 is moved in the direction B, the counter 35e is incremented, the image is read for one line, and the image data buffer 3 for the image data.
5a is stored (ST120), and this processing is repeatedly executed until the position of the CCD line sensor 9 obtained based on the count value of the counter 35e reaches the reading start designated position data of the reading command.

When the position of the CCD line sensor 9 obtained based on the count value of the counter 35e reaches the reading start designated position data of the reading command, it is judged that the reading is finished, and the execution of the reading operation (ST120) is finished. Yes (ST12
1).

Thereafter, the line sensor unit 12 is moved from that position until the CCD line sensor 9 is out of the reading area 4 (ST122), and then the stepping motor 1 is moved.
4 is driven in the direction A by the correction value N steps, and the next read command is input at that position. In the case of driving for the correction value N steps, the counting process of the counter 35e is not performed (ST123).

In the above, ST113 to ST115,
ST122 and ST123 are forward reading control means, and S
T117 to ST121 are reverse reading control means.

As described above, according to this embodiment, when the reading operation is started, the reference position data for obtaining the position of the CCD line sensor 9 is selected in accordance with the moving direction of the CCD line sensor 9 performed in the reading operation. In addition, since the stepping motor 14 is driven for the number of steps for correcting the hysteresis, the movement of the line sensor unit 12 in the reading operation becomes faithful to the driving of the stepping motor 14 from the beginning of the reading operation. Position can be managed accurately.

Therefore, even if there is hysteresis due to play in the moving mechanism, the hysteresis is specified in both the forward and backward directions without affecting the reading area accuracy of the image reading operation by the CCD line sensor 9. The reading area can be read accurately.

Since this image reading device can continuously perform the reciprocating operation to perform the reading, the effect can be further exerted when the original is continuously read using the automatic paper feeding device.

[0039]

According to the present invention, as the count value of the counting means for controlling the position of the reading means during movement,
The position of the reading means during forward movement is controlled based on the count value when the reference marker is detected during forward movement of the reading means, and the reading means based on the count value when the reference marker is detected during backward movement of the reading means. Since the position during the backward movement of the reading means is controlled, the position of the reading means which is assumed to be controlled by the control means and the actual reading means are not required in the reading operation of the reading means during the reciprocating movement. The actual position is surely coincident with each other, and high-quality image data having no deviation in the sub-scanning direction between the image data in reciprocal reading can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical hardware configuration of a device according to an embodiment of the present invention.

2 is a main part configuration diagram of the embodiment apparatus shown in FIG. 1 as viewed from a side surface.

FIG. 3 is a configuration diagram of a main part of the apparatus of the embodiment shown in FIG. 1 viewed from above.

FIG. 4 is a configuration diagram showing an opening / closing mechanism of the embodiment apparatus shown in FIG.

5 is a flowchart showing a process when the power of the apparatus of the embodiment shown in FIG. 1 is turned on.

FIG. 6 is a flowchart showing processing at the time of reading by the apparatus of the embodiment shown in FIG.

[Explanation of symbols]

 4 glass plate (document holding means) 9 CCD line sensor (reading means) 13 moving mechanism 14 stepping motor (driving means) 20 reference marker 22 document holding plate (document holding means) 35b reference position data storage unit (storage unit) 35c reference Position data storage unit (storage unit) 35d Correction value storage unit (storage unit) 35e Counter (counting means)

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[Procedure amendment]

[Submission date] November 2, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 4]

[Figure 5]

[Figure 6]

Claims (1)

[Claims] 1. An image reading device for moving a reading unit relative to a document holding unit for holding a document in the sub-scanning direction, and reading one line for each predetermined movement amount. Drive means for moving the means via a moving mechanism, counting means for increasing or decreasing the count value from the standby position according to the drive direction corresponding to the unit drive amount of the drive means, and the sub-scanning direction of the document holding means. And a reference marker provided outside the reading area, and stores the count value of the counting means when the reading means detects the reference marker during its movement,
Based on the stored count value and the count value of the counting means, the relative position of the reading means with respect to the document holding means in the moving process is managed, and the reading means is moved forward to be designated from the reading start designated position. And an image reading apparatus that performs a reading operation of the original from a designated reading end position by moving the reading unit backward, and driving the driving unit forward so that the reading unit moves the forward movement of the reference marker. Means for reading out the count value N1 from the standby position of the counting means when detecting, and the drive means for driving the drive means in the backward direction to detect the reference marker in the course of the backward movement of the reading means. Means for reading the count value N2 from the standby position of the counting means, means for calculating a correction value N from the count values N1, N2, the count values N1, N2, At least 2 of positive values N
A storage unit for storing one as management data, and the drive unit based on the count value N1 based on the count value of the counting unit and the management data of the storage unit after the reading operation of the reading unit in the backward movement is completed. The drive amount is determined, and the drive unit is moved forward by a drive amount corresponding to at least the correction value N to move the reading unit to the reading start designated position.
A forward reading control unit that continuously drives the driving unit to perform a reading operation in a forward direction, and based on the count value of the counting unit and the management data of the storage unit after the reading operation of the reading unit in the forward movement is completed. , The drive amount of the drive means is determined based on the count value N2, and the drive means is driven backward by a drive amount corresponding to at least the correction value N to move the read means to the read end designated position. ,
An image reading apparatus, further comprising: a backward reading control unit that drives the driving unit backward to perform a backward reading operation.