JPH0980638A - Scanning method and device for use in slit exposure type optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a scanning method and device for use in a slit exposure type optical device, which prevent concentration of repeated bending stresses on a specific position on wire rope to enhance durability. SOLUTION: In a scanning method for use in a slit exposure type optical device in which first 5 and second 6 scanners are scanned along a document and an image of the document is projected onto a photoconductor drum 15, after the number of scans counted by a counter 12 has reached a preset number of scans, a speed change means 16, a travel distance setting means 17, and a linear velocity change means 19 change either one or more of the scanning speed and distance of the scanners and the linear velocity of the photoconductor. The position on wire rope to which bending stresses are repeatedly applied is changed to enhance durability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device such as a copying machine or an image scanner which adopts a slit exposure system.

[0002]

2. Description of the Related Art In a slit exposure type optical apparatus, a document with an image surface facing down is placed on a contact glass, and the document is scanned from below by an exposure scanner to form a projected image on a photosensitive drum. There is.

FIG. 4 is a diagram showing an exposure scanner portion in such a conventional optical device. In the scanning drive of the exposure scanner shown in the same figure, a motor 1 is used as a drive source, a wire rope 3 as a drive transmission means is wound around a drive pulley 2 of the motor, and further each pulley 4, 4 is provided.
.. is wound, and the wire rope 3 is fed out and pulled back by controlling the rotation speed of the motor 1 to move the first scanner 5
Also, the second scanner 6 is moved back and forth.

When the start of copying is instructed from the operation panel of the optical device (not shown), the first scanner 5 moves in the direction of arrow V.
, And the second scanner 6 starts moving in the same direction at a speed of V / 2. When the first scanner reaches a position beyond the length of the document, it stops and then starts a return operation, and the first and second scanners 5 and 6 move in opposite directions and return to their original positions. . Here, when the "certain position" at which the image is stopped is referred to as a turning point, the turning point is determined to be a fixed position depending on the size of the original document. Since you can copy about the size,
The turning points are set to different positions for each size.

On the other hand, since the wire rope 3 is wound around the drive pulley 2, the wire rope 3 is repeatedly subjected to bending stress depending on the rotation speed and the rotation direction of the drive pulley 2. In particular, since the speed at the time of return is higher than that at the time of scanning, rapid acceleration / deceleration is required, and a large force is applied to a specific place of each wire rope 3.

Further, in recent copying machines, speedup,
Although high durability is required, at the same time, in general offices, the standardization of document sizes is progressing, and therefore the ratio of repeated bending stress concentration at the same location on the wire rope is increasing.

When stress is repeatedly applied to the same place, fatigue at that place increases, shortening the life of the wire rope and deteriorating its durability.

[0008]

The present invention has been made in view of the above facts, and improves the durability of the wire rope by preventing the bending stress from repeatedly concentrating on a specific place of the wire rope. Accordingly, it is an object of the present invention to provide a scanning method or a scanning device having excellent durability.

Another object of the present invention is to provide a scanning method or a scanning device in which the copy speed does not decrease when the durability of the wire rope is improved.

Another object of the present invention is to provide a scanning method or a scanning device in which the quality of a copy image is not deteriorated when the durability of the wire rope is improved.

Still another object of the present invention is to provide a scanning method or a scanning device in which the copy image is not underexposed when the durability of the wire rope is improved.

[0012]

In order to achieve the above object, the scanning method of the present invention is a slit exposure type optical apparatus for scanning a scanner along a document and projecting a document image on a photosensitive drum. In the scanning method, the number of scans is counted, and after the count reaches a preset number of scans, any one or more of the scanning distance, the scanning speed, and the photoconductor linear velocity of the scanner is switched. There is.

In the above method, the number of scans may be counted for each size of the document, and the preset number of scans may be determined for each size of the document.

Further, the scanning distance, the scanning speed, and the linear velocity of the photoconductor are all increased, the light quantity of the exposure light source is increased from before the switching, and the developing bias voltage of the developing device is increased as compared with that before the switching. be able to.

The scanning device of the present invention is a scanning device in a slit exposure type optical device having a scanner for scanning an original and a photosensitive drum on which the original image is projected by the scanner, and the number of scans is counted. A counter, a speed conversion means for converting the speed of the scanner, a moving distance setting means for the scanner, and a linear speed conversion means for converting the linear speed of the photosensitive drum are featured.

Further, the counter is provided for each original size, a light source drive means for increasing / decreasing the light amount of the exposure light source is provided, and a voltage changing means for increasing / decreasing the developing bias voltage of the developing device by the photosensitive drum is provided. It can be provided.

In advance, when the upper limit of the number of scans for each document size in consideration of durability is exceeded, the scanning distance, the scanning speed, and the linear velocity of the photosensitive member are switched to determine the location where the repeated bending stress of the wire rope is received. You can change it to avoid fatigue in one place and improve durability.

By increasing all of the above scanning distance, scanning speed, and linear velocity of the photosensitive member, it is possible to prevent the copy speed from decreasing. If the light quantity of the exposure light source is increased more than before switching,
It is possible to prevent the copy image from being underexposed. If the developing bias voltage of the developing device is increased compared to before switching,
It is possible to prevent the quality of the copied image from deteriorating.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view of a slit exposure type scanning device portion according to the present invention. When the original 10 is fed onto the contact glass 11, the original size detecting means 12a
Scans the document size. Next, the first scanner 5 moves in the arrow direction at a speed of V along the document, and the second scanner 6
Similarly scans by moving in the direction of the arrow at a speed of V / 2. The image of the original is refracted by the lens system 13 through the first scanner 5 and the second scanner 6 and is reflected by the fixed reflecting mirror 14 to project the original image on the photosensitive drum 15. When one copy is made, the auxiliary counter 12b counts one from the number of movements of the second scanner 6. Auxiliary counter 12
Although b sends a count signal to a control unit (not shown), the control unit separates the count for each document size together with the signal from the document size detection means 12a. Therefore, the counter 12 is composed of the document size detecting means 12a and the auxiliary counter 12b.

As described with reference to FIG. 4, the first scanner 5 and the second scanner 6 have a drive pulley 2 attached to a motor 1 as a drive source and a drive transmission means (wire rope) wound around the drive pulley. 3 is scanned. The motor 1 is provided with a speed conversion device 16 and a moving distance setting means 17 using an encoder, and a computer (not shown) also performs feedback control based on pulse signals from these devices to control the first and second scanners. The scanning speed and scanning distance are controlled. Speed converter 16
For example, a type in which the rotation speed is controlled by increasing / decreasing the pulse frequency is used. Also,
The photoconductor drum 15 includes a linear velocity conversion unit 18 that changes the photoconductor linear velocity by increasing or decreasing its rotation speed, and a developing roller 19.
A voltage conversion unit 20 that increases or decreases the bias voltage applied to is provided. The first scanner 5 has a light source 5 for exposure.
a is provided with the light source driving means 21 so that the light amount of the light source 5a can be increased or decreased.

FIG. 2 shows a velocity diagram of the first scanner 5 and a torque diagram of the drive source. In the velocity diagram of (a),
When a scanner start signal is input, the area is accelerated to a predetermined speed V in the area t1 and is scanned at a constant speed during the time t2 (the area is the image forming area). In the area t3, the image formation is completed and the speed is reduced to zero. The period from t1 to t3 is called a scan operation. Further, a period from t4 to t6 is called a return operation. At t4, the speed direction is opposite to the scanning operation, and the maximum speed (Max-
V), decelerates during t5, and stops at t6. These are a series of scanning operations.

Next, looking at the torque diagram of (b), it can be seen that a large amount of torque is required in the acceleration / deceleration regions t4 and t5. Especially, in the t4 region, the maximum torque (Max-T) is required in order to accelerate the return operation. That is, a large force is applied to the wire rope 3 at the beginning of the return operation.

FIG. 3 shows a comparison between an actual scanner and a velocity diagram. Since the horizontal axis (time or distance) in the diagrams shown in the lower part of each of FIGS. 1A and 1B is positive in the right direction, the moving direction of the optical member is opposite to that in FIG.

The first scanner 5 and the second scanner 6 are initially stopped with the 0 point as a reference position, and when the document size is determined by an operation unit (not shown) or the like, the document size or the paper size + oversize. The scan operation is performed up to point A (turning point) of the run distance, and the return operation is performed from point A to point 0. This operation is repeated for the preset number of scans of the counter to form an image on the photosensitive drum 15 (FIG. 3A).

If the original size is the same, the turning point is always the same position (for example, A4 size A
Point), the portion of the wire rope 3 that is in contact with the drive pulley 2 at that time is easily damaged, and the durability of the wire rope is deteriorated.

In the present invention, in consideration of the life of the wire rope 3, the upper limit of the scanning number is written in the ROM or RAM (not shown) of the computer controlling the counter 12, and the scanning number is stored for each document size. .
Then, when the number of times exceeds the preset number of times of scanning, the scanning distance, the scanning speed, and the linear velocity of the photoconductor are switched.

That is, the computer instructs the moving distance setting means 17 by a signal from the counter to change the scanning distance from 0 point to A point to 0 point to B point, and the computer also instructs the speed converting means 16. And scan speed V
→ Change to V '. Further, the linear velocity converting means 18 is instructed to switch the linear velocity of the photoconductor from Vo to Vo '(FIG. 3).
(B)).

The scanning distance, the scanning speed, and the photoconductor linear velocity after the switching may all be decreased or increased as compared with those before the switching, but if they are decreased, the copying speed is reduced. Therefore,
To prevent the copy speed from decreasing, it is desirable to increase it. To do this, scan operation + return operation = 1
The reciprocating scanning time (t1 to t6) is the same before and after switching.

Further, in the present invention, since the linear velocity Vo of the photosensitive drum 15 is increased to Vo '(Vo <Vo') after switching, the exposure light amount to the photosensitive drum 15 is greater than that before switching. Run short. Therefore, the light source drive signal from the light source drive unit 21 can be changed to increase the light amount of the light source 5a in the first scanner 5, and correction can be performed so that the exposure light amount to the photosensitive drum 15 is not insufficient.

If the amount of exposure light is insufficient in other operations, the developing roller 19 of the developing device is used for correction.
The developing bias voltage applied to is increased by the voltage converting means 20 and is corrected.

The light amount of the light source 5a for exposure and the developing roller 19
It may be simultaneously increased with the developing bias voltage applied to.

In the above embodiment, the position of the turning point A is different for each document size, but it is applicable to an optical device of the type in which the turning point is the same regardless of the document size. is there.

[0033]

According to the present invention as described above,
When the upper limit of the number of scans in consideration of the durability of the wire rope is exceeded in advance, the scanning distance, the scanning speed, and the photosensitive member linear velocity are switched, so that a highly durable optical device can be obtained. In this case, when the moving distance of the scanner differs depending on the document size, the upper limit of the number of scans may be set for each document size.

Further, if the scanning distance, the scanning speed, and the linear velocity of the photosensitive member are increased as compared with those before the switching, the scanning time can be kept the same, so that the reduction of the copying speed can be prevented.

If the shortage of the exposure light amount to the photosensitive drum after switching is corrected by increasing the light amount of the exposure light source,
Even after switching, it is possible to obtain a high-quality image with little background stain.

Further, if the insufficient exposure light amount to the photosensitive drum after the switching is corrected by increasing the developing bias voltage of the developing device, the high quality image with less background stain can be obtained. You can

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of a scanning device in a slit exposure type optical device of the present invention.

2A and 2B are diagrams showing control of the scanning device, wherein FIG. 2A is a velocity diagram and FIG. 2B is a torque diagram.

3A and 3B are diagrams showing a comparison between the scanning device of the present invention and a velocity diagram, where FIG. 3A shows the case where the number of scanning times is within the upper limit, and FIG. 3B shows the case where the upper limit is exceeded.

FIG. 4 is a perspective view of a scanning device in a conventional slit exposure type optical device.

[Explanation of symbols]

 5, 6 Scanner 12 Counter 15 Photosensitive Drum 16 Velocity Converting Means 17 Moving Distance Setting Means 18 Linear Velocity Converting Means 20 Voltage Converting Means 21 Light Source Driving Means

Claims (9)

[Claims] 1. A scanning method in a slit exposure type optical device for scanning a scanner along a document to project a document image on a photosensitive drum, the number of scans is counted, and the number of scans is preset. After reaching
A scanning method in a slit exposure type optical device, characterized in that any one or more of a scanning distance, a scanning speed, and a photoconductor linear velocity of the scanner is switched. 2. The slit exposure type optical system according to claim 1, wherein the number of times of scanning is counted for each size of the document, and the preset number of times of scanning is determined for each size of the document. Scanning method in a device. 3. The scanning method in a slit exposure type optical device according to claim 2, wherein all of the scanning distance, the scanning speed, and the linear velocity of the photosensitive member are increased. 4. A scanning method in a slit exposure type optical apparatus according to claim 3, wherein the light amount of the exposure light source is increased more than before switching. 5. A scanning method in a slit exposure type optical device according to claim 4, wherein the developing bias voltage of the developing device is increased as compared with that before switching. 6. A scanning device in a slit exposure type optical device having a scanner for scanning along a document and a photosensitive drum on which a document image is projected by the scanner, a counter for counting the number of scans, and a scanner for the scanner. A scanning device in an optical apparatus of slit exposure system, comprising: speed conversion means for converting speed; moving distance setting means for the scanner; and linear speed conversion means for converting linear speed of the photosensitive drum. . 7. The scanning device according to claim 6, wherein the counter is provided for each document size. 8. The scanning device in the slit exposure type optical device according to claim 7, further comprising a light source driving means for increasing or decreasing the light amount of the exposure light source. 9. The scanning device in the slit exposure type optical device according to claim 8, further comprising voltage changing means for allowing the photosensitive drum to increase or decrease a developing bias voltage of the developing device.