JP2000184142A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader which can prevent disturbance of an image caused by overshooting or the like due to the inertia of a scanning optical system by reducing the impact of acceleration to gently run the scanning optical system in an image read area at the time of intermittent read operation. SOLUTION: At the time of acceleration of a stepping motor in the case of intermittent read operation, approach control is performed stepwise plural times, for example, an acceleration area (1) at a certain acceleration (a), a non-acceleration area (2) at a certain speed, an acceleration area at another acceleration a', a non-acceleration area (4) at the certain speed,... are set, and thus, the impact of acceleration is reduced to gently run the scanning optical system in the image read area, and disturbance of an image caused by overshooting or the like due to inertia of the scanning optical system is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanner in a digital copying machine or a facsimile, and an image reading apparatus such as an image scanner.

[0002]

2. Description of the Related Art Generally, in an image reading apparatus of this type, a document image set on a contact glass is slit-exposed by a light source, and reflected light from the document is reflected by a one-dimensional CCD or the like via a mirror, an image forming lens or the like. The image is read by forming an image. Here, in order to two-dimensionally read a document image, a light source, a mirror, and the like are mounted on a traveling body as a scanning optical system, and are configured to reciprocate in a sub-scanning direction under driving by a stepping motor.

On the other hand, this type of image reading apparatus is provided with a line buffer for sequentially storing read image data. When the line buffer is full, reading is temporarily interrupted and the system waits until the line buffer becomes empty. The operation is controlled as follows. Such operation control is known as intermittent reading as shown in, for example, JP-A-6-205181 and JP-A-6-31315. Therefore, in the intermittent reading operation, it is necessary to temporarily stop the stepping motor for the scanning optical system in the image reading area of the document and restart it when the stopped state is released. Such an intermittent reading operation is not limited to the case of a facsimile disclosed in Japanese Patent Application Laid-Open No. 6-205181. For example, when an image reading signal from the host computer to the scanner is interrupted due to the processing of the host computer or the like. Similarly, the scanner temporarily stops the reading operation (the stepping motor is also stopped),
It is necessary to wait for an image reading request signal.

[0004] Recently, as the size and weight of the image reading apparatus have been reduced, the time and distance of acceleration or deceleration of the scanning optical system have tended to be shortened. There is a growing demand for higher image quality during intermittent reading.

[0005]

However, usually, in the case of intermittent reading, the time and distance of acceleration and deceleration from the outside of the image reading area to the inside of the image reading area are directly set in the image reading area during the intermittent reading. Only the time and distance of acceleration and deceleration are used, and subsequent thinning processing is performed to read an image. For example, JP-A-6-3
Referring to the example shown in Japanese Patent No. 7984, etc., during the intermittent reading operation, as shown in FIG. 7, after the stepping motor is decelerated at a constant acceleration and temporarily stopped, and then accelerated at a constant acceleration to drive the stepping motor. By doing so, the scanning optical system is advanced so as to be in a constant speed driving state.

However, the above-described acceleration and deceleration control of the stepping motor during the intermittent reading operation alone causes problems such as image distortion, swaying, shaking, and missing due to overshoot due to inertia during acceleration or deceleration. Can occur.

Accordingly, the present invention reduces the impact of acceleration in the image reading area during the intermittent reading operation to provide a gentle approach, thereby preventing image distortion due to overshoot or the like due to inertia of the scanning optical system. It is an object of the present invention to provide an image reading device that can be obtained.

Further, the present invention achieves the above object by reducing the amount of memory used and facilitating control.

Further, the present invention achieves the above object more effectively.

In order to achieve the above object, the present invention can cope with a change in magnification at the time of electronic magnification reading in which the reading speed is changed.

[0011]

According to the first aspect of the present invention,
In an image reading apparatus provided with a stepping motor for driving a scanning optical system for reading a document image in the sub-scanning direction with respect to the document, the stepping motor is temporarily stopped within an image reading area of the document to read intermittently. An intermittent operation start-up control means is provided for performing the start-up control for accelerating the stepping motor when performing the operation in a stepwise manner by repeating an acceleration region at a different acceleration and a non-acceleration region at a constant speed.

Therefore, when the stepping motor is accelerated during the intermittent reading operation, an acceleration region at a certain acceleration-a non-acceleration region at a constant speed-an acceleration region at another certain acceleration-a non-acceleration region at a constant speed- By performing the approach control a plurality of times step by step as described above, a gentle approach with reduced impact of acceleration in the image reading area can be obtained, and image disturbance due to overshoot or the like due to inertia of the scanning optical system can be prevented.

According to a second aspect of the present invention, in the image reading apparatus of the first aspect, the intermittent operation approach control means includes:
When the reading operation is performed intermittently, the stop control for decelerating the stepping motor is performed stepwise in a pattern opposite to that for the run-in control for performing the acceleration.

Therefore, the approach control for accelerating and the stop control for deceleration have the same control pattern in terms of time-speed, so that the table can be unified between the approach control and the stop control. In addition, the number of tables used can be reduced and control can be facilitated.

According to a third aspect of the present invention, in the image reading apparatus according to the first aspect, the different accelerations relating to the plurality of acceleration regions are such that the constant speed of the stepping motor is higher in the acceleration region on the stop side of the stepping motor. It is set to a value larger than the acceleration region on the drive side.

Therefore, the acceleration is similar to that of the first aspect of the invention, but the acceleration gradually decreases as the speed of the stepping motor increases. A good run.

According to a fourth aspect of the present invention, in the image reading apparatus of the first aspect, the intermittent operation approach control means includes:
At the time of electronic variable-magnification reading, the approach control for accelerating the stepping motor is changed in accordance with the change in the electronic variable magnification.

Therefore, the approach control at the time of the intermittent reading operation is changed in accordance with the change of the magnification at the time of electronic scaling, so that the image is disturbed by the intermittent reading operation by coping with any change of the reading speed. Can be prevented.

According to a fifth aspect of the present invention, in the image reading apparatus of the second aspect, the driving current value of the stepping motor when the reading operation is performed intermittently is a driving current value in a non-acceleration region at a constant speed. The value is set lower than the drive current value in the acceleration region and the deceleration region at different accelerations.

Therefore, the driving current value in the non-acceleration region at a constant speed during the intermittent reading operation is different from the driving current value in the acceleration region and the deceleration region at different accelerations. Since it is set lower than that, it is possible to reduce shock and vibration at the time of acceleration and deceleration, and to prevent disturbance of an image due to overshoot, vibration and the like due to inertia of the scanning optical system.

According to a sixth aspect of the present invention, in the image reading device of the fifth aspect, the intermittent operation approach control means comprises:
At the time of electronic magnification reading, the drive current value of the stepping motor is changed and controlled in accordance with the change in the run-in control due to the change in the electronic magnification.

Accordingly, the drive current value of the stepping motor during the intermittent reading operation is changed and controlled in accordance with the change in the run-in control due to the change in the magnification at the time of electronic scaling, so that any change in the reading speed is possible. Optimum drive current value control of the stepping motor is achieved, and image disturbance due to intermittent reading operation can be prevented.

[0023]

FIG. 1 shows a first embodiment of the present invention.
A description will be given with reference to FIG. The image reading apparatus according to the present embodiment is applied to, for example, a scanner that is connected to a host computer and performs an operation of reading a document image. FIG. 1 is a front view showing a schematic configuration of a scanner optical system in the scanner. First, a fluorescent lamp 3 for exposing a document 2 set on a contact glass 1 is provided. The reflected light from the document 2 exposed by the fluorescent lamp 3 is sequentially reflected by the first, second, and third mirrors 4, 5, and 6, and then is imaged on the one-dimensional CCD 8 by the imaging lens 7. . Here, the fluorescent lamp 3 or the third mirror 6 is provided movably on the lower surface of the contact glass 1 in the sub-scanning direction, and forms a scanning optical system 9. Among them, the fluorescent lamp 3 and the first mirror 4 are mounted on a first traveling body 9a, and the second and third mirrors 5, 6 are mounted on a second traveling body 9b. 9b is configured to be driven in the same direction at a speed ratio of 2: 1.

FIG. 2 is a perspective view showing an example of the configuration of a driving system for such a scanning optical system 9. Stepping motor 1 as a drive source for driving scanning optical system 9 in the sub-scanning direction
0 is provided. A drive wire 12 is wound on a motor pulley 11 of the stepping motor 10. As is well known, the driving wire 12 is appropriately wound around the guide pulley 13 and the like, and
A part thereof is locked to both ends of the first and second traveling bodies 9a and 9b so that a and 9b are driven in the same direction at a speed ratio of 2: 1.

FIG. 3 is a schematic block diagram showing a hardware configuration of a control system for such a scanner unit. A one-chip CPU 14 including a memory such as a ROM and a RAM for controlling the entire scanner unit is mounted on an optical control board 15. A ballast 16 for turning on the fluorescent lamp 3 and an IPU (image processing device) 17 for receiving an image signal from the one-dimensional CCD 8 are controlled by a one-chip CPU 14. Also, the operation of the stepping motor 10 is controlled by the one-chip CP.
It is controlled by U14. Here, the function of the intermittent operation running control means described later is executed by the one-chip CPU 14.

Under such a schematic configuration, the first and second traveling bodies 9a, 9b are driven by the stepping motor 10 in response to an image reading request signal for each line sent from the host computer. Document 2 at 2: 1 speed ratio
The document image is sequentially read while moving along (sub-scanning). By this operation, the one-dimensional CCD 8
The image signal which is formed into the image and photoelectrically converted is transferred to the host computer. At this time, if the image reading request signal from the host computer is interrupted due to the processing of the host computer or the like, the reading operation is temporarily stopped and one chip is set so as to wait for the image reading request signal to be sent again. The CPU 14 controls the operation. This operation is executed as an intermittent reading operation.

Here, the operation control of the stepping motor 10 in such an intermittent reading operation will be described with reference to FIG. In the present embodiment, the approach control time T for accelerating the stepping motor 10 for moving the first and second traveling bodies 9a and 9b from outside the image reading area to the image reading area (the stop control time for deceleration is the same). In addition to the above, when the intermittent reading operation is performed in the image reading area,
An approach control time t for accelerating the stepping motor 10 for moving the traveling bodies 9a and 9b and a stop control time t 'for decelerating are set. here,
t = t ′.

The control pattern within the run-in control time t includes an acceleration region at an acceleration a-a non-acceleration region at a constant speed-an acceleration region at an acceleration a'-a non-acceleration region at a constant speed (target speed). -It is a pattern in which the approach control is performed stepwise a plurality of times, such as-. The accelerations a and a 'are set in a magnitude relationship such that a>a'.

The control pattern within the stop control time t 'includes a non-acceleration region at a constant speed (target speed) -a deceleration region at an acceleration a'-a non-acceleration region at a constant speed'-acceleration a The stop control is performed stepwise a plurality of times, such as in the deceleration region '-. The accelerations a and a 'are set in a magnitude relationship such that a>a'. That is, the control is performed in a pattern completely opposite to that during the approach control. This is because the approach control for accelerating and the stop control for deceleration have the same control pattern in terms of time-speed and are stored as a table in the ROM of the one-chip CPU 14. That is, the table can be unified for the approach control and the stop control, and the number of tables used can be reduced and the control can be facilitated.

During the intermittent reading operation, the one-chip CPU 14
Referring to the control pattern in this table, the run-in control and the stop control are performed as shown in FIG. This control is performed by a one-chip CPU 1
4 is performed. Therefore, according to the control at the time of the intermittent reading operation of the present embodiment, a gentle approach with reduced impact of acceleration in the image reading area is obtained, and the scanning optical system 9 (first and
Image disturbance due to overshoot or the like due to the inertia of the two traveling bodies 9a, 9b) is prevented, and good image reading becomes possible. In particular, since the acceleration in the acceleration region in the control pattern is set so that the acceleration gradually decreases as the arrival speed of the stepping motor 10 increases (a> a '), the acceleration when reaching the predetermined speed is reduced. The impact can be reduced more effectively and a gentle approach can be made.

In accordance with a change in the magnification in the main scanning direction read by the one-dimensional CCD 8, that is, a change in the electronic magnification, the reading speed in the sub-scanning direction is also changed. This change also affects the intermittent reading operation, and the reading control speed t and the stop control time t 'are also changed by changing the reading speed in accordance with the change in the electronic magnification. Here, in the present embodiment, the control pattern (especially, acceleration and the like) is changed in accordance with the change in the approach control time t and the stop control time t ′ accompanying the change in the electronic magnification change. Is set. Therefore, it is possible to cope with any change in the reading speed and prevent the image from being disturbed due to the intermittent reading operation.

A second embodiment of the present invention will be described with reference to FIG. The same portions as those described in the first embodiment are denoted by the same reference numerals (the same applies to the following embodiments). In this embodiment, basically, similarly to the case of the first embodiment, a stepping motor 10 for moving the first and second traveling bodies 9a and 9b during the intermittent reading operation in the image reading area. Run control time t for accelerating with respect to
In addition, a stop control time t 'for performing deceleration is set.
Here, t = t '.

The control pattern within the run-in control time t is as follows: acceleration region at acceleration a-non-acceleration region at constant speed-acceleration region at acceleration a'-non-acceleration region at constant speed (target speed) -It is a pattern in which the approach control is performed stepwise a plurality of times, such as-. The accelerations a and a 'are set in a magnitude relationship such that a>a'.

The control pattern within the stop control time t 'includes a non-acceleration region at a constant speed (target speed) -a deceleration region at an acceleration a'-a non-acceleration region at a constant speed'-acceleration a The stop control is performed stepwise a plurality of times, such as in the deceleration region '-. The accelerations a and a 'are set in a magnitude relationship such that a>a'. That is, the control is performed in a pattern completely opposite to that during the approach control. This is because the approach control for accelerating and the stop control for deceleration have the same control pattern in terms of time-speed and are stored as a table in the ROM of the one-chip CPU 14. That is, the table can be unified for the approach control and the stop control, and the number of tables used can be reduced and the control can be facilitated.

In addition to the operation control according to the first embodiment, in the present embodiment, the driving current value of the stepping motor 10 at the time of the intermittent reading operation in the image reading area is not accelerated at a constant speed. The drive current values in the regions are set lower than the drive current values in the acceleration region and the deceleration region at different accelerations. That is, the driving current value B in the non-acceleration region ′ is A> B, A ′> B with respect to the driving current value A in the acceleration region and the driving current value A ′ in the deceleration region ″.
Are set to satisfy the following relationship.

By controlling the drive current value of the stepping motor 10 at the time of the intermittent reading operation in the image reading area in this way, it is possible to reduce the shock and vibration at the time of acceleration and deceleration. Image disturbance due to overshoot, vibration or the like due to inertia of the bodies 9a and 9b can be prevented.

A third embodiment of the present invention will be described with reference to FIG. With the change in the magnification in the main scanning direction read by the one-dimensional CCD 8, that is, the change in the electronic magnification, the reading speed in the sub-scanning direction is also changed. This change
This also affects the intermittent reading operation, and the change in the reading speed accompanying the change in the magnification of the electronic scaling changes the run control time t and the stop control time t '. Here, in the present embodiment,
The control pattern (particularly, the drive current value of the stepping motor 10 and the like) is set to be changed in accordance with the change in the approach control time t and the stop control time t ′ accompanying the change in the electronic magnification. I have. In the example shown in FIG. 6, the current values A1, A1 ', B1 at the time of reduction (A1> B1, A1'>
B1), current values A2, A2 ', B2 (A
2> B2, A2 ′> B2), but A1> A2, A1 ′> A
2 ', B1> B2.

Therefore, according to this embodiment, the most suitable stepping motor 1 can be used for any change of the reading speed.
The drive current value control is set to 0, and the disturbance of the image due to the intermittent reading operation can be prevented.

Although these embodiments are applied to a scanner connected to a host computer, they can also be applied to a digital copying machine, a scanner unit of a facsimile, and the like. The scanning optical system 9 is applied to a type in which the scanning optical system 9 is separated into first and second traveling bodies 9a and 9b and driven at a speed ratio of 2: 1. The same can be applied to the case of a scanning optical system of the contact sensor type.

[0040]

According to the first aspect of the present invention, when the stepping motor is accelerated during the intermittent reading operation, an acceleration region at a certain acceleration-a non-acceleration region at a constant speed-an acceleration region at another certain acceleration. -The non-acceleration area at a constant speed-The approach control is performed multiple times step by step, so that the impact of acceleration in the image reading area is reduced to provide a gentle approach, and the inertia of the scanning optical system causes Image disturbance due to overshoot or the like can be prevented.

According to the second aspect of the invention, the approach control for accelerating and the stop control for deceleration have the same control pattern in terms of the time-speed relationship. And the number of tables used can be reduced and control can be facilitated.

According to the third aspect of the invention, it is the same as the first aspect of the invention, but in particular, the acceleration gradually decreases as the speed of the stepping motor increases, so that the acceleration impact is reduced. It is possible to reduce the movement more effectively and perform a gentle approach.

According to the fourth aspect of the present invention, the approach control at the time of the intermittent reading operation is changed in accordance with the change in the magnification at the time of electronic scaling, so that any change in the reading speed can be dealt with. Thus, it is possible to prevent the image from being disturbed due to the intermittent reading operation.

According to the fifth aspect of the present invention, the driving current value in the non-acceleration region at a constant speed during the intermittent reading operation is different from that of the second aspect of the invention. Since the drive current value is set lower than the drive current value in the area and the deceleration area, it is possible to reduce shock and vibration during acceleration and deceleration, and to prevent image distortion due to overshoot and vibration due to inertia of the scanning optical system.

According to the sixth aspect of the present invention, the drive current value of the stepping motor during the intermittent reading operation is controlled to be changed in accordance with the change in the run-in control due to the change in the magnification during electronic magnification. Therefore, the drive current value of the stepping motor is controlled optimally for any change in the reading speed, and the disturbance of the image due to the intermittent reading operation can be prevented.

[Brief description of the drawings]

FIG. 1 is a front view showing a schematic configuration of a scanner optical system according to a first embodiment of the present invention.

FIG. 2 is a perspective view illustrating a configuration example of a driving system for a scanning optical system.

FIG. 3 is a schematic block diagram illustrating a hardware configuration of a control system.

FIG. 4 is a time chart showing a control sequence in a time-speed relationship.

FIG. 5 is a time chart showing a control sequence in a time-speed relationship according to the second embodiment of the present invention.

FIG. 6 is a time chart showing a control sequence in a time-speed relationship according to the third embodiment of the present invention.

FIG. 7 is a time chart showing a conventional control sequence in a time-speed relationship.

[Explanation of symbols]

 2 Original 9 Scanning optical system 10 Stepping motor

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) // H04N 1/04

Claims (6)

[Claims] 1. An image reading apparatus comprising a stepping motor for driving a scanning optical system for reading a document image in a sub-scanning direction with respect to the document, temporarily stopping the stepping motor in an image reading area of the document. Intermittent operation run control means for performing the run control for accelerating the stepping motor when performing the reading operation intermittently by repeating an acceleration region at a different acceleration and a non-acceleration region at a constant speed in a stepwise manner. An image reading apparatus comprising: 2. The intermittent operation approach control means performs stop control for decelerating the stepping motor when performing an intermittent reading operation in a stepwise manner according to a pattern opposite to the acceleration control for performing the acceleration. 2. The image reading apparatus according to claim 1, wherein the image reading is performed. 3. The different accelerations relating to the plurality of acceleration regions are set to a larger value in an acceleration region on a stop side of the stepping motor than in an acceleration region on a constant speed driving side of the stepping motor. The image reading device according to claim 1, wherein: 4. The intermittent operation approach control means changes the approach control for accelerating the stepping motor in response to a change in electronic magnification during electronic magnification reading. 2. The image reading device according to 1. 5. The driving current value of the stepping motor when the reading operation is performed intermittently is different from the driving current value in the acceleration region and the deceleration region in the acceleration where the driving current value in the non-acceleration region at a constant speed is different. 3. The image reading device according to claim 2, wherein the image reading device is also set at a low level. 6. The electronic control unit according to claim 1, wherein the intermittent operation run control unit changes and controls the drive current value of the stepping motor in response to a change in the run control due to a change in the electronic magnification during the electronic magnification reading. The image reading device according to claim 5, wherein