JP2002082396A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader with which an image quality is improved by preventing shifts in position, due to the step-out of a driving motor to move a traveling body to which a scanning optical system is mounted. SOLUTION: Since the image reader 1 is returned only by a pulse by which it is moved in a forward direction to perform image reading, the traveling body is moved in a return direction only by the pulse by inverting a stepping motor; and when an HP sensor is turned on, a pulse number applied to the stepping motor when the HP sensor is turned on is checked concerning whether a normal pulse number, and when it is the normal pulse number, it is judged that step-out has not occurred. When the pulse number applied to the stepping motor is not the normal pulse number, it is judged that the step-out has occurred, either in the forward direction or the return direction by a difference between the pulse number applied to the stepping motor, when the HP sensor is turned on and the normal pulse number, and also a pulse number for making positional correction is set (steps S201-S204).

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, and more particularly, to an image reading apparatus which prevents a drive motor for moving a traveling body equipped with a scanning optical system in a sub-scanning direction of a document from being out of synchronization, and The present invention relates to an image reading device that improves image quality.

[0002]

2. Description of the Related Art In an image reading apparatus such as a copying machine or a facsimile machine, a traveling body equipped with a scanning optical system is moved in a sub-scanning direction of a document set on a contact glass to perform main scanning and sub-scanning. Then, the image of the document is read.

As a drive motor for driving the traveling body, a stepping motor having excellent control characteristics is often used.

However, in an image reading apparatus, an over-specification stepping motor is usually used in consideration of an increase in aging load of an optical system (document reading scanning optical system), so that the cost increases and Even if an over-spec stepping motor is used, there is a possibility that step-out may occur for some reason depending on the installation of the image reading apparatus, the use environment, and the like, and there is a possibility that the image quality may deteriorate due to the step-out.

Therefore, conventionally, a scanning means for scanning and reading a document image, a driving means for reciprocating the scanning means in a predetermined direction, and a start-up for starting the driving means in a predetermined number of steps to a predetermined scanning speed. Storage means for storing a plurality of patterns, control means for selecting one start-up pattern stored in the storage means and controlling acceleration or deceleration of the drive means, and scanning by drive of the drive means Position detecting means for detecting a predetermined scanning position of the scanning means; determining means for determining out-of-step of the driving means from the predetermined scanning position detection state by the position detecting means; The control means changes the start-up pattern selected from the storage means to another start-up pattern. Location has been proposed (JP-A-8-2
04908).

[0006]

However, such a conventional image reading apparatus requires storage means for storing a plurality of start-up patterns for starting the driving means at a predetermined scanning speed in a predetermined number of steps. At the same time, when trying to memorize start-up patterns corresponding to various patterns such as normal rotation, reverse rotation, and scaling of switching,
As the storage capacity of the storage means increases, the rise pattern is changed, so that the cpm of the stepping motor is changed, and unless the home position is searched, the stepping motor is lost and the position is shifted. As a result, there is a problem that the image quality may be deteriorated due to the step-out of the stepping motor, and the price may increase due to the large capacity of the storage means.

In view of the above, a first aspect of the present invention is to read a document image by moving a traveling body on which a scanning optical system for performing main scanning by irradiating a document with light is moved in a sub-scanning direction by a drive motor. The position of the traveling body is detected by the position detection means, and the presence or absence of step-out of the drive motor is determined based on the detection result of the position detection means. Based on the occurrence state of the document, the position of the traveling body is corrected within a predetermined time set in advance from the standby state, thereby correcting the displacement and continuously reading the image of the document without interrupting the reading of the document. It is therefore an object of the present invention to provide an image reading apparatus which reads an image, does not need to change a startup pattern, and does not need to store a large number of patterns, and is inexpensive and has good image quality of a read image.

According to a second aspect of the present invention, the position of the traveling body is corrected in a short time by increasing the output torque of the drive motor, thereby correcting the position of the traveling body in a short time. It is an object of the present invention to provide an even better image reading device.

According to a third aspect of the present invention, by correcting the position of the running body by shifting the image reading timing, the position of the running body can be corrected more easily, and the image quality of the read image can be reduced at a lower cost. It is an object of the present invention to provide a good image reading apparatus.

According to a fourth aspect of the present invention, when the drive motor loses synchronism, the output of the drive motor is changed to prevent subsequent loss of synchronism. It is an object of the present invention to provide a better image reading device.

[0011]

According to a first aspect of the present invention, there is provided an image reading apparatus, wherein a scanning optical system for irradiating a document with light and performing main scanning is mounted on a traveling body, and the traveling body is sub-scanned by a drive motor. In the image reading device that reads an image of a document while moving in the direction, the position of the traveling body is detected by position detection means, and the presence or absence of step-out of the drive motor is determined based on the detection result of the position detection means. When the step-out of the drive motor has occurred, the position of the traveling body is corrected within a predetermined period of time from a standby state based on the state of occurrence of the step-out, thereby achieving the above object. Have achieved.

According to the above arrangement, the traveling body on which the scanning optical system for irradiating the original with light and performing main scanning is moved in the sub-scanning direction by the drive motor to read the image of the original. The position is detected by the position detection means, and the presence or absence of step-out of the drive motor is determined based on the detection result of the position detection means. Since the position of the traveling body is corrected within a predetermined time set from the standby state based on the standby state, the position deviation can be corrected, and the image of the document can be continuously read without interrupting the reading of the document. Can be performed, eliminating the need to change the startup pattern,
By eliminating the need to store a large number of patterns, the image reading apparatus can be inexpensive and have good image quality of the read image.

In this case, for example, the image reading device may correct the position of the traveling body by increasing the output torque of the drive motor.

According to the above construction, since the position of the traveling body is corrected by increasing the output torque of the drive motor, the position of the traveling body can be corrected in a short time, and the image reading apparatus can read the image at low cost. Can be further improved in image quality.

Also, for example, the image reading device may correct the position of the traveling body by shifting an image reading timing.

According to the above arrangement, since the position of the traveling body is corrected by shifting the image reading timing, the position of the traveling body can be corrected more easily, and the image reading apparatus can be read at a lower cost. The image quality of the image can be good.

Further, for example, as described in claim 4, the image reading device may change the output of the drive motor when the drive motor loses synchronism.

According to the above configuration, if the drive motor loses synchronism, the output of the drive motor is changed, so that subsequent loss of synchronism can be prevented. The image quality can be further improved.

[0019]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. It should be noted that the embodiments described below are preferred embodiments of the present invention, and therefore, various technically preferable limitations are added. However, the scope of the present invention is not limited to the following description. The embodiments are not limited to these embodiments unless otherwise specified.

FIGS. 1 to 6 show an embodiment of the image reading apparatus of the present invention. FIG. 1 shows an image reading apparatus 1 to which the embodiment of the image reading apparatus of the present invention is applied. It is a principal part perspective view.

In FIG. 1, an image reading apparatus 1 includes a first traveling body 2 and a second traveling body 3, and both ends of a first traveling body 2 and a second traveling body 3, which are disposed to extend in the main scanning direction. A pair of wires 4 disposed in the sub-scanning direction, a pair of wire pulleys 5a to 5d respectively disposed on both ends of the first traveling body 2 and the second traveling body 3 in the sub-scanning direction and supporting the wires 4, Wire 4
, A pair of wire pulleys 7 attached to the vicinity of both ends of the drive shaft 6 around which the wire 4 is wound, and a timing belt pulley attached to one end of the drive shaft 6 8, a timing belt pulley 10 connected to the timing belt pulley 8 by a timing belt 9, a stepping motor 11 for driving the timing belt pulley 10 to rotate, and a home position sensor disposed near the home position of the traveling bodies 2, 3 ( Hereinafter, the detection unit 1 is attached to the first traveling body 2 and detected by the HP sensor 12.
3 and so on.

The image reading apparatus 1 includes a stepping motor 1
By controlling the rotation of 1, the main scanning is performed while moving the first traveling body 2 and the second traveling body 3 in the sub-scanning direction, and the image of the document is read.

That is, when the stepping motor 11 is driven to rotate, the timing belt pulley 10 rotates, and the timing belt pulley 9
Then, the drive shaft 6 rotates, the wire pulley 7 connected to the drive shaft 6 rotates, and the wire 4 supported by the wire pulleys 5a to 5d rotates. As the wire 4 rotates, the first traveling body 2 and the second traveling body 3 connected to the wire 4
Moves in the sub-scanning direction. At this time, the first traveling body 2 and the second traveling body 3 are driven by the second traveling body 3 at half the speed of the first traveling body 2 so that the first traveling body 2 and the second traveling body 3 2 to 1
A sub-scanning system with a speed ratio of?

As shown in FIG. 2, the traveling bodies 2, 3 and the like are arranged in the image reading apparatus 1 below the contact glass 14, and the original to be read is set on the contact glass 14. Is done.

The first traveling body 2 includes a contact glass 1
Exposure lamp 15 for irradiating light on the original set on 4
And a first mirror 16 that reflects light reflected by the document in the direction of the second traveling body 3.
Is equipped with a second mirror 17 and a third mirror 18 that reflect light reflected from the first traveling body 2 in the home position direction.

The image reading apparatus 1 further includes an imaging lens 19, a CCD (Charge Coupled Device) 20, a scanner control plate 21, a drive control plate 22, and the like.

The reflected light from the third mirror 18 of the second traveling body 3 is incident on the imaging lens 19 and the imaging lens 1
9 forms an image of the incident light on the CCD 20. CCD20
Performs photoelectric conversion of incident light and transfers the image data to the scanner control board 21 as image data. The scanner control board 21 performs necessary image processing on the transferred image data.

When the power switch is turned on, the image reading apparatus 1 executes the stepping motor 1 for homing.
1 starts driving, and the first traveling body 2 and the second traveling body 3
When the HP sensor 12 moves to the forward side indicated by an arrow and moves a certain distance, it starts reverse rotation (return), and when the HP sensor 12 detects the detecting unit 13 provided at the lower part of the first traveling body 2, a certain pulse Move a minute and stop. This position is the home position HP, and this home position HP
When the start key of the operation unit of the image reading apparatus 1 is scanned and a reading command is issued, the reading operation is started.

Then, the stepping motor 11 corresponds to FIG.
As shown in (1), the drive is controlled by the drive control plate 22, and the drive control plate 22 receives the stepping motor drive clock, the forward / reverse rotation signal, and the drive current switching signal from the scanner control plate 21 on which the host CPU is mounted. Is done. The drive control plate 22 controls the drive current flowing through each phase of the stepping motor 11 based on these signals to control the drive of the stepping motor 11.

The speed of the stepping motor 11 is determined by the frequency of the driving clock. That is, the drive control plate 22 controls the phase switching timing of the stepping motor 11 according to the drive lock frequency. When the drive clock frequency is high, the rotation speed of the stepping motor 11 increases, and when the drive clock frequency is low, the stepping motor 11 Rotation speed becomes slow. By controlling the driving clock frequency, a wide variety of slow-ups can be performed. In addition, the drive current can be controlled, and the drive control plate 22 controls the switching of the current depending on the state such as slow-up, slow-down, reading operation, return, and standby.

When the original is placed on the contact glass 14 and the start key is pressed, the image reading apparatus 1 outputs a drive clock from the scanner control board 21 to the drive control board 22 at a predetermined timing, and outputs a stepping motor. 1
At the same time as the start of the driving of the first traveling body, the first traveling body 2 and the second traveling body 3 are started to move forward from the home position HP.

The drive control plate 22 controls the drive of the stepping motor 11 based on the speed pattern of the stepping motor 11 as shown in FIG.

That is, the first traveling body 2 and the second traveling body 3 start traveling in the forward direction by the driving of the stepping motor 11 and irradiate the original placed on the contact glass 14 with the exposure lamp 14. The reflected light is imaged on the CCD 20 by the imaging lens 19 via the first mirror 16, the second mirror 17, and the third mirror 18, and the image of the original is read. The CCD 20 transfers the read image data to the scanner control board 21 and performs necessary image processing on the scanner control board 21.

Then, as shown in FIG. 4, the document is read from the leading edge to the trailing edge of the original during a period in which the first traveling body 2 and the second traveling body 3 travel at a constant speed after the stepping motor 11 slows down. During this period, the speed needs to be stabilized most.

When the reading of the original is completed, the process proceeds to the return process, and the drive control plate 22
1, the first traveling body 2 is moved at high speed, and the second traveling body 3 is returned at high speed at half the speed.

When the HP sensor 12 detects the detector 13 provided on the first traveling body 2, the drive control plate 22
Moves the stepping motor 11 by a fixed pulse,
Stop at the HP position.

The homing for moving the first traveling body 2 and the second traveling body 3 to the home position HP is as follows.
The processing is performed when the power is turned on, after the paper jam processing and the abnormal processing are completed, and the processing is performed as shown in FIG.

That is, it is checked whether the HP sensor 12 is on (the detection plate 11 is in) or off (the detection plate 11 is out) (step S10).
1) When the HP sensor 1212 is on, the first traveling body 2 and the second traveling body 3 are moved in a direction in which the HP sensor 12 is turned off (forward direction) until the HP sensor 12 is turned off (step S101). , S102).

When the HP sensor 12 is turned off in step S101, the HP sensor 12 moves by a specified pulse and stops (step S103), and then starts moving in the direction in which the HP sensor 12 turns on (return direction) (step S104). When the sensor 12 is turned on, it moves in the return direction by a prescribed pulse and stops. This position corresponds to the first traveling body 2 and the second traveling body.
The home position HP of the traveling body 3 is set.

Next, the operation of the present embodiment will be described. The image reading device 1 according to the present embodiment includes a stepping motor 1
When step-out of step 1 is detected, the amount of misalignment from the home position HP is detected to correct the positions of the first traveling unit 2 and the second traveling unit 3 to accurately perform the continuous reading operation. is there.

That is, as shown in FIG. 4, the image reading apparatus 1 starts moving the first traveling body and the second traveling body 3 in the forward direction by the stepping motor 11, and performs an image reading process. After moving the specified pulse amount, the image reading apparatus 1 starts operation to return by the number of pulses moved in the forward direction, and when the detection plate 11 enters the HP sensor 12 and the HP sensor 12 is turned on, the specified Move in the amount return direction and stop.

When the stepping motor 11 loses synchronism during the series of operations shown in FIG. 4, the first traveling body 2 and the second traveling body 2
The home position HP of the traveling body 3 shifts.

Therefore, the image reading apparatus 1 of the present embodiment
Determines whether or not step-out has occurred based on whether the number of pulses given to the stepping motor 11 when the HP sensor 12 is turned on is a prescribed number of pulses. If step-out has occurred, the home position HP , And corrects the positions of the first traveling body 2 and the second traveling body 3 to enable an accurate continuous reading operation.

That is, as shown in FIG. 6, the image reading apparatus 1 reverses the stepping motor 11 by returning the stepping motor 11 in order to return by the number of pulses moved in the forward direction for image reading, as described above. When the first traveling body 2 and the second traveling body 3 are moved in the return direction by the number of pulses, it is checked whether the detection plate 11 has entered the HP sensor 12 and the HP sensor 12 has been turned on (step S201), and has not been turned on. Sometimes, the stepping motor 11 is reversed until the HP sensor 12 is turned on.

In step S201, if the HP sensor 12 is turned on, it is checked whether the number of pulses given to the stepping motor 11 when the HP sensor 12 is turned on is a specified pulse number (step S202). If it is a number, no step-out has occurred, and there is no need to perform position correction, so the correction processing ends.

In step S202, if the number of pulses applied to the stepping motor 11 when the HP sensor 12 is turned on is not the specified number of pulses, the number of pulses applied to the stepping motor 11 when the HP sensor 12 is turned on is equal to the specified number. It is checked whether it is smaller than the pulse number (step S203). If the pulse number is smaller than the specified pulse number, step-out has occurred in the forward direction, and the first traveling body 2 has gone too far in the forward direction than the home position HP. Then, the number of pulses for adding the position correction amount is set, and the correction processing ends (step S204).

In step S203, if the number of pulses applied to the stepping motor 11 when the HP sensor 12 is turned on is larger than the specified number of pulses, step-out has occurred in the return direction, and the first traveling body 2 It is determined that the motor has stopped before the home position HP, the number of pulses for subtracting the position correction amount is set, and the correction processing ends (step S205).

Steps S204 and S20
When the correction setting of the pulse amount in 5 is performed, the position correction of the first traveling body 2 and the second traveling body 3 is performed as follows.

That is, when the number of plus pulses is set as the correction amount, the stepping motor 11 is driven in the forward direction by the number of plus pulses within the standby time shown in FIG. And the second traveling body 3 is moved, and waits until the next forward driving starts.

When the number of negative pulses is set as the correction amount, the clock for starting driving in the next forward direction shown in FIG. 4 is shifted in the forward direction from the clock immediately after the output of the set negative pulses. Is controlled to start driving.

In this manner, the displacement can be corrected, and the image of the document can be read continuously without interrupting the reading of the document.
It is not necessary to change the start-up pattern, and it is not necessary to store a large number of patterns, so that the image reading apparatus 1 can be inexpensive and have good image quality of the read image.

When the number of plus pulses is set as the correction amount, the image reading apparatus 1 sets the time within a short standby time (50 m).
In s), it is necessary to move several pulses to several tens of pulses to perform the correction at a higher speed, so that a high torque is required.

Therefore, the drive current of the stepping motor 11 is increased to increase the output torque to perform the correction operation. When the correction operation is completed, the drive current is reduced to prevent the temperature of the stepping motor 11 and the driver of the drive control plate 22 from rising. To the normal drive current.

In this way, the traveling bodies 2 and 3 can be moved in a short time.
And the image reading device 1 can be made inexpensive and the image quality of the read image can be further improved.

Further, the image reading device 1 detects the step-out by the step-out detection process and sets the image reading start timing shown in FIG. The image reading is started with a delay. Next, when the number of negative pulses is set as the correction amount, reading is started earlier than the image reading start timing shown in FIG.

In this manner, the position correction of the traveling bodies 2 and 3 can be performed more easily, and the image reading device 1 can be made more inexpensive and have a good image quality of the read image.

Step-out detection processing detects step-out, and the HP
If the number of pulses given to the stepping motor 11 when the sensor 12 is turned on is less than the prescribed number of pulses, the stepping motor 11 is almost out of step in the forward direction. The output of the stepping motor 11 is increased to prevent the step-out. If the number of pulses given to the stepping motor 11 when the HP sensor 12 is turned on is larger than a specified number of pulses, the stepping motor 11 is driven in the return direction because the stepping motor is almost out of step in the return direction. To increase the output of the stepping motor 11 to prevent step-out.

In this manner, subsequent step-out can be prevented, and the image reading apparatus 1 can be made inexpensive and the image quality of the read image can be further improved.

Although the invention made by the inventor has been specifically described based on the preferred embodiments, the invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the invention. It goes without saying that it is possible.

[0060]

According to the image reading apparatus of the first aspect of the present invention, the traveling body on which the scanning optical system for performing main scanning by irradiating the original with light is moved in the sub-scanning direction by the drive motor. When reading the image of the document, the position of the traveling body is detected by the position detecting means, and it is determined whether or not the drive motor has stepped out based on the detection result of the position detecting means. In this case, the position of the traveling body is corrected within a predetermined period of time from the standby state based on the state of occurrence of the step-out, so that the positional deviation can be corrected and the reading of the document can be interrupted. Without changing the start-up pattern, eliminating the need to store a large number of patterns, making the image reading apparatus inexpensive and having a good image quality of the read image. Shall Door can be.

According to the image reading apparatus of the present invention, the position of the traveling body is corrected by increasing the output torque of the drive motor, so that the position of the traveling body can be corrected in a short time. The image reading device can be made inexpensive and the image quality of the read image can be further improved.

According to the image reading apparatus of the present invention, the position of the traveling body is corrected by shifting the image reading timing, so that the position of the traveling body can be more easily corrected. The reading device can be made even more inexpensive and the image quality of the read image is good.

According to the image reading apparatus of the present invention, if the drive motor loses synchronism, the output of the drive motor is changed, so that subsequent loss of synchronization can be prevented. The reading device can be made inexpensive and the image quality of the read image can be further improved.

[Brief description of the drawings]

FIG. 1 is a perspective view of an optical scanning system of an image reading apparatus to which an embodiment of the image reading apparatus of the present invention is applied.

FIG. 2 is a front sectional view of a main part of the image reading apparatus of FIG. 1;

FIG. 3 is a diagram showing a control system of a drive control plate and a stepping motor of FIG. 2;

FIG. 4 is a view showing an example of a traveling control speed pattern of the traveling body by the image reading apparatus of FIG. 1;

FIG. 5 is a flowchart illustrating homing control processing by the image reading apparatus of FIG. 1;

FIG. 6 is a flowchart showing a step-out detection / correction amount detection process by the image reading apparatus of FIG. 1;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 image reading device 2 first traveling body 3 second traveling body 4 wire 5 a to 5 d wire pulley 6 drive shaft 7 wire pulley 8, 10 timing belt pulley 9 timing belt 11 stepping motor 12 HP sensor 13 detection unit 14 contact glass 15 exposure lamp 16 First mirror 17 Second mirror 18 Third mirror 19 Imaging lens 20 CCD 21 Scanner control board 22 Drive control board

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H04N 1/107

Claims (4)

[Claims] An image reading apparatus for reading a document image by mounting a scanning optical system for irradiating light on a document and performing main scanning on a traveling body, and moving the traveling body in a sub-scanning direction by a drive motor. The position of the traveling body is detected by position detection means, and the presence or absence of step-out of the drive motor is determined based on the detection result of the position detection means. An image reading apparatus, wherein the position of the traveling body is corrected within a predetermined period of time from a standby state based on a step-out occurrence state. 2. The image reading device according to claim 1, wherein the image reading device corrects the position of the traveling body by increasing an output torque of the drive motor. 3. The image reading apparatus according to claim 1, wherein the image reading apparatus corrects the position of the traveling body by shifting an image reading timing. 4. The image reading apparatus according to claim 1, wherein the output of the drive motor is changed when the drive motor loses synchronism. Image reading device.