JPH03113471A - Optical system driving device for image forming device - Google Patents

Abstract

PURPOSE:To simplify the structure and to permit optical system scanning to be exact by providing a clutch change control means which changes a clutch so as to transmit the driving force of a main motor to optical systems until the output of a detecting means is obtained from the start of returning motion and the changes a clutch so as to transmit the driving force of a stepping motor to the optical systems for other period. CONSTITUTION:Scanning by going motion is performed by changing the clutch 9 and transmitting the driving force of the stepping motor 8 to the optical systems 2 and 3. When the scanning by the optical systems 2 and 3 is completed, the clutch 10 is changed, the driving force of the main motor 44 is transmitted to the optical systems and the returning motion of the optical systems 2 and 3 is started from the scanning completed position. When the optical systems 2 and 3 are returned to the prescribed position in a shifting range, the return is detected, the clutch 9 is changed again and the drive of the optical systems by the stepping motor 8 is continued to the shift starting position. Thus, the structure is simplified and the optical system scanning is permitted to be exact.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention provides an optical system for projecting the contents of an original onto a photoreceptor by projecting the contents of the original onto a photoreceptor using an optical system that is disposed facing the original table. The present invention relates to an optical system driving device for an image forming apparatus that scans along the image forming apparatus.

[Conventional technology]

Conventionally, in an optical system scanning image forming apparatus having a reduction or enlargement function, when performing a same-size copy, the optical system is driven by the main motor of the image forming apparatus, and the direction of movement of the optical system is switched between forward and backward paths. This is performed by a forward rotation clutch and a reverse rotation clutch provided between the main motor and the drive pulley of the optical system. The moving speeds of the optical system on the outward and return trips are set such that the speed on the return trip is several times faster than the speed on the outward trip, depending on the gear ratio of the forward rotation clutch and the reverse rotation clutch.

Furthermore, when performing reduction or enlargement copying, the lens section is moved to a predetermined position according to the magnification by a dedicated stepping motor, and the optical system is driven by a dedicated servo motor at a moving speed according to the magnification. ing.

[Problem to be solved by the invention]

By the way, the optical system (including the lens section) of the above-mentioned conventional image forming apparatus is driven by a dedicated motor that changes the motor depending on the copying magnification, which makes the structure complicated and also makes manufacturing difficult. This is disadvantageous in terms of cost.

To solve these problems, for example, when performing reduction or enlargement copying, a servo motor for moving the optical system is used instead of a stepping motor for moving the lens, and the servo motor moves the lens part and the optical system. Although it is conceivable to have a servo motor perform this operation, the control of a servo motor is more complicated than that of a stepping motor, and the control circuit is also larger, which is disadvantageous in terms of space and cost advantages.

On the other hand, it is conceivable to use a stepping motor in place of the servo motor for moving the optical system, but as is well known, stepping motors have the characteristic that their torque decreases as the rotational speed increases, so scanning ends When the optical system is later returned to the movement start position, there may be a step-out or a lack of torque, which makes it impossible to increase the rotational speed of the stepping motor, resulting in a problem that copying time is required. For this reason, it is conceivable to use a stepping motor only for document scanning, which can be driven at relatively low speed and low torque, and to switch to the main motor using a clutch to drive the return movement after scanning, which requires high speed and high torque. .

However, in this case, since the movement M of the optical system is controlled by clutch switching control, it becomes difficult to accurately return the optical system to the movement start position.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide an optical system drive device for an image forming apparatus that has a simple structure and can scan an optical system accurately.

[Means to solve the problem]

In order to solve the above problems, the present invention provides an optical system driving device for an image forming apparatus that reciprocates an optical system within a movement range, and provides a main motor, a stepping motor, and a driving force from the main motor and the stepping motor. a clutch that switches and transmits the signal to the optical system, a detection means that detects that the optical system has returned to a predetermined position in the moving range, and a main motor The apparatus further includes clutch switching control means for switching the clutch to transmit the driving force to the optical system, and switching the clutch to transmit the driving force of the step motor to the optical system during periods other than the above.

Furthermore, the stepping motor may be driven during the return operation of the optical system from the time when the optical system is moved by a predetermined amount ω from the scan end position to the movement start position.

[Effect]

In the drive device for the optical system of the pixel forming apparatus configured as described above, forward scanning is performed by switching the clutch and transmitting the driving force of the stepping motor to the optical system. When the scanning by the optical system is completed, the clutch is switched to transmit the driving force of the main motor to the optical system, and the optical system starts to move back from the scanning end position. Then, when the optical system returns to a predetermined position within the movement range, this is detected, the clutch is switched again, and the driving of the optical system by the stepping motor is continued until the movement start position.

Further, when the optical system moves by a predetermined amount from the scanning end position, this is detected, the clutch is switched again, and the driving of the optical system by the stepping motor is continued until the movement start position.

(Example) An optical system drive device of an image forming apparatus according to the present invention will be described with reference to FIGS. 1 to 3.

FIG. 1 is a side view of essential parts of an optical system drive device of a copying machine. In the figure, reference numeral 1 indicates a contact glass disposed on a document table at the top of the main body of the copying machine, and reference numeral 2 indicates a frame 21 slidably attached to a guide rod 5, and a contact glass disposed on the movable frame 21. A first optical system includes a light source 22 such as a halogen lamp, a reflector 23, and a reflector 24; 3 is a movable frame 31 slidably attached to the guide rod 5; This is a second optical system consisting of reflective mirrors 32 and 33 provided. 4 is a wire for driving the first optical system 2 and the second optical system 3, which includes a pulley (not shown) fixed to the main body of the copying machine, and a movable wire arranged on the movable frame 31 of the second optical system. It is stretched around the pulley 34 and the driving pulley 7, and a part thereof is fixed to the moving frame 21 of the first optical system 2 with a fixing member 25. Reference numeral 6 denotes a timing switch disposed at a suitable location within the main body of the copying machine for detecting the timing at which the first optical system 2 starts scanning an original. The timing switch 6 detects that the first optical system 2 has moved to the document scanning start point by detecting a detected member 26 such as a magnet attached to the moving frame 21 of the first optical system 2. do. Further, the timing signal generated by the timing switch 6 is also used as a timing signal for disengaging a clutch 10, which will be described later, in order to stop the optical system when the optical system moves from the scan end position to the movement start position. Ru. 7
A drive pulley is fixed to a drive shaft (not shown), and a gear 7a is formed at one end thereof. 8 is a stepping motor for driving the first and second optical systems 2.3 to scan the original; 9 is a clutch for transmitting the driving force of the stepping motor to the driving pulley 7; 10 is not shown; This is a clutch for transmitting the driving force of the main motor to the driving pulley 7. Note that the main motor is a transport system motor for driving the photoreceptor drum, fixing roller, and the like. Gears 11 are provided at both ends of the rotating shaft of the clutch 9.
The gear 11 meshes with the gear 7a of the drive pulley 7, and the gear 12 meshes with the gear 13 fixed to the drive shaft of the stepping motor 8. A gear 14 is fixed to one end of the rotating shaft of the clutch 10, and a pulley 15 is fixed to the other end. It is connected to a pulley (not shown) fixed to the drive shaft of the motor.

Note that the stepping motor 8 may be directly connected to the drive pulley 7 via the gear 13, excluding the clutch 9 and gears 11 and 12. Further, the lens portion (not shown) may be driven using a dedicated stepping motor as in the conventional method, but may also be driven using the stepping motor 8.

In this case, a clutch having the same structure as the clutch 9 and having gears 11 and 12 is connected to the gear 13, and the driving force of the stepping motor 8 is transmitted to the lens portion through this clutch.

In the above configuration, the contents of the document are projected onto the photoreceptor by scanning the first and second optical systems 2 and 3 in the six directions of arrows. In this case, as will be described later, the clutch 10 is disengaged, the clutch 9 is engaged, and the driving force of the stepping motor 8 is transmitted to the drive pulley 7 to drive the drive pulley 8 in forward rotation (in the figure, direction of arrow B). When returning the first and second optical systems 2.3 after scanning, the clutch 9 is disengaged, the clutch 10 is engaged, and the driving force of the main motor is transmitted to the drive pulley 7. The driving pulley 8 is driven in the reverse direction. As described above, the operations of the clutches 9 and 10 correspond to the drive direction of the drive pulley 7, so hereinafter, the clutch 9 will be referred to as a forward rotation clutch and the clutch 10 will be referred to as a reverse rotation clutch.

FIG. 2 is a system configuration diagram of the optical system drive device of the copying machine. In this figure, the same members as those shown in FIG. 1 are given the same numbers. 40 is a microcomputer (hereinafter referred to as microcomputer) that controls the copying operation of the copying machine; 41 is a copy key provided on the operation panel of the copying machine body for instructing the start of copying; 42 is a copy key provided on the operation panel; A document size setting key 43 is an output circuit that outputs a control signal to drive the main motor 44 and stepping motor 8 in response to a command signal from the microcomputer 40.

The microcomputer 40 controls the driving of the main motor 44 and the stepping motor 8 based on the copy start signal from the copy key 41 and the timing signal from the timing switch 6, and also controls the driving of the reverse rotation clutch 9 and the forward rotation clutch 1.
Controls the binding operation of 0. Also, the document size setting key 4
The scanning distance and speed are calculated based on the size setting signal from 2, and the rotation ω and speed of the stepping motor are controlled.

Next, using the flowchart in FIG. 3, we will explain how to drive the optical system of the copying machine according to the present invention. The operation of the II device will be explained.

First, when the copy key 41 is turned on (#1), the reverse rotation clutch 10 is turned off, the forward rotation clutch 9 is turned on, and the driving force from the stepping motor 8 is connected to the optical system (#2). Subsequently, the main motor 44 is started and the drive of the conveyance system such as the photosensitive drum and the conveyance roller is started (#3), and then the main charger is turned on.
Main charging of the photosensitive drum is performed, and the halogen lamp 22 of the first optical system 2 is turned on (#4). Next, the stepping motor 8 is started and driven by a predetermined amount to move the optical system by a predetermined amount, that is, a distance corresponding to the document size.The stepping motor 8 is then turned off and the optical system is moved to the scanning end position. Stop it (#5.#6).

Then, when the stepping motor 8 is turned off, the halogen lamp 22 and the main charger are turned off to end the exposure of the photosensitive drum (#7). Subsequently, the forward rotation clutch 9 is turned off, and the reverse rotation clutch 10 is turned on, and the driving force of the main motor 44 is connected to the optical system, and the return movement of the optical system to the movement start position is started (#
8). Then, the optical system is moved by the main motor 44 until the timing switch 6 is turned on, and when the timing switch 6 is turned on, the reverse rotation clutch 10 is turned off, and the forward rotation clutch 9 is turned on (#10), and the stepping motor 8 The drive source is main motor 4.
Switched from 4 to stepping motor 8 (#11)
. Then, after driving the stepping motor 8 by a predetermined amount to move the optical system by a predetermined distance, the stepping motor 8 is turned off to stop the optical system (#12), and the forward rotation clutch 9 and main motor 44 are turned off. Turn it off and end the copy operation (#13 to #15). Note that the stepping motor 8 is driven by the timing switch 6.
A value corresponding to the distance from the position of the optical system detected by 1 to the movement start position is set in advance, and by driving the stepping motor 8 by this set value, the optical system is stopped at the movement start position.

By the way, in the above embodiment, the optical system is moved [! The drive source for the optical system was switched from the main motor 44 to the stepping motor 8 upon detecting that the main motor 44 had returned to the predetermined position within the frame.
The drive source for the optical system may be switched from the time when the optical system has returned from the scanning end position by a predetermined amount.

Next, this second embodiment will be explained using FIGS. 4 and 5. FIG. 4 shows a system configuration diagram of an optical system drive device of a copying machine according to a second embodiment. In this figure, the same members as in FIG. 2 are given the same numbers. Further, 45 is a clock plate provided, for example, on the coupled portion side of the reverse clutch 10. Reverse clutch 1
0 is coupled and the driving force from the main motor is transmitted, clock pulses having a period corresponding to the rotational speed are generated from the clock plate 45 and input to the microcomputer 40.

The microcomputer 40 counts these clock pulses, and when a preset count value is reached, controls the engagement of the reverse rotation clutch 9 and the forward rotation clutch 10 to switch the drive source of the optical system from the main motor 44 to the stepping motor 8. .

FIG. 5 is a flowchart showing the operation of the optical system drive device of the copying machine according to the second embodiment.

The operational flow shown in this figure is basically the same as the operational flow of the first embodiment shown in FIG. 3, so the explanation will focus on the different operational steps.

As explained in the first embodiment, when the optical system starts the copying operation and finishes scanning the original, the forward rotation clutch 9 is turned off, and the reverse rotation clutch 10 is turned on, and the drive source of the optical system is turned off. The stepping motor 8 is switched to the main motor 44 (#1 to #8). At approximately the same time as this, the return operation of the optical system is started, and counting of clock pulses output from the clock plate 45 is started (#9).

Then, when the count reaches a preset count value and a borrow signal is generated (#10), the reverse clutch 10
is turned off, the forward rotation clutch 9 is turned on, the stepping motor 8 is started, and the drive source is switched from the main motor 44 side to the stepping motor 8 side (
#11. #12). Then, the optical system is moved by the step motor 8 until the timing switch 6 is turned on.
When the timing switch 6 is turned on, that is, when it is detected that the optical system has returned to the scanning/scanning start position, the stepping motor 8 is further driven by the preset drive ω as described above, and then the stepping motor 8 is moved to the movement start position. The optical system is stopped by turning it off (#13 and #14), and the forward rotation clutch and the main motor 44 are turned off to complete the copying operation (#15 to #17).

〔Effect of the invention〕

As explained above, according to the present invention, when returning the optical system to the movement start position after the end of scanning, the optical system is driven by the main motor during the movement period when a large torque is required, and is driven with a relatively small torque. Since the optical system is driven by the stepping motor for a predetermined period or range before the possible movement start position, it is possible to accurately return the optical system to the movement start position v1. Additionally, the main motor and stepping motor are used as the drive source for the optical system depending on the load, simplifying the drive source.
The structure can be simplified and costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a side view of essential parts showing the optical system drive device of the image forming apparatus according to the present invention, FIG. 2 is a system configuration diagram of the optical system drive device of the image forming apparatus according to the present invention, and FIG. 3 is the present invention. A flowchart showing the operation of the optical system drive device according to
FIG. 4 is a system configuration diagram of the optical system driving device of the image forming apparatus according to the second embodiment, and FIG. 5 is a flowchart showing the operation of the optical system driving device according to the second embodiment. 2... First optical system, 3... Second optical system, 4... Wire, 5... Guide rod, 6... Timing switch, 7... Driving pulley, 8... Stepping motor, 9.10...Clutch, 11-14...Gear, 1
5...Pulley, 16...Timing belt, 26...
...Member to be detected, 40...Microcomputer, 41...Copy key 42...Document size setting key, 43...Output circuit, 44...Main motor, 45...Clock board.

Claims (1)

[Scope of Claims] 1. In an optical system drive device of an image forming apparatus that reciprocates an optical system within a movement range, the driving force from the main motor, the stepping motor, or the main motor and the stepping motor is switched. A clutch that transmits power to the optical system, a detection means that detects when the optical system has returned to a predetermined position within the moving range, and a drive force of the main motor that is transmitted to the optical system from the start of the return movement until the output of the detection means is obtained. and a clutch switching control means for switching the clutch to transmit the driving force of the step motor to the optical system during a period other than the above. Optical system drive device. 2. In the optical system driving device for an image forming apparatus according to claim 1, the optical system is moved back by a predetermined amount from the scanning end position in place of the detection means for detecting that the optical system has returned to a predetermined position in the movement range. 1. An optical system driving device for an image forming apparatus, characterized in that the optical system driving device includes a detection means for detecting that the