JPH03113470A - Optical system driving device for image forming device - Google Patents

Abstract

PURPOSE:To simplify the structure and to reduce the cost by providing a clutch change control means which changes a clutch so as to transmit the driving force of a stepping motor to optical systems when the device is in going motion and that changes a clutch so as to transmit the driving force of the main motor to the optical systems when the device is in returning motion. CONSTITUTION:The device is provided with the clutches 9 and 10, which change the driving force from the main motor 44 and the stepping motor 8 and transmit to the optical systems 2 and 3, and the clutch change control means 4a, which changes the clutch 9 so as to transmit the driving force of the stepping motor 8 when the device is in the going motion and that changes the clutch 10 so as to transmit the driving force of the main motor 44 when the device is in the returning motion. In such a manner, scanning by the 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 is completed by the optical systems 2 and 3, the clutch 10 is changed, the driving force of the main motor 44 is transmitted to the optical systems 2 and 3 and the returning motion of the optical systems from the scanning completed position is started. Thus, the structure is simplified and the cost is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides an optical system that is arranged opposite to a document table to project the contents of the document onto a photoreceptor. The present invention relates to an optical system drive device for an image forming apparatus that scans along a line.

[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 optical system drive boolean. 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.

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. .

[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, with the motor being switched depending on the copying magnification, which makes the structure complex and makes it difficult to manufacture. It is also disadvantageous in terms of cost. To solve these problems, for example, when performing reduction or enlargement copying, a stepping motor is used instead of a servo motor for moving the optical system, and the stepping motor moves the lens section and the optical system. It is possible to do so. However, as is well known, stepping motors have the characteristic that the torque decreases as the rotational speed increases, so when returning the optical system to the starting position after scanning, it may lose synchronization or lack torque. There is. Therefore, the rotational speed of the stepping motor cannot be increased, and it takes time to restore the optical system, resulting in a problem that the copying time becomes longer.

On the other hand, it is conceivable to use a servo motor for moving the optical system instead of a stepping motor for moving the lens, but servo motors are more complex to control than stepping motors, and the control circuit is also larger, resulting in space advantages and costs. Disadvantages in terms of merits.

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

[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 by switching between a main motor, a stepping motor, and the driving force from the main motor and the stepping motor. a clutch that transmits the driving force to the optical system, and switches the clutch to transmit the driving force of the stepping motor to the optical system during forward movement, and switches the clutch to transmit the driving force of the main motor to the optical system during backward movement. Clutch switching control means.

(Function) In the drive device for the optical system of the image 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, the driving force of the main motor is transmitted to the optical system, and the optical system starts to move back from the scanning end position.

〔Example〕

An optical system drive device of an image forming apparatus according to the present invention will be explained using 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 3 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 a guide rod 5; This is a second optical system consisting of reflections 1t32 and 33 arranged therein. 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 is the first
By detecting a detected member 26 such as a magnet attached to the moving frame 21 of the optical system 2, it is detected that the first optical system 2 has moved to the document scanning start point. Furthermore, 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 and 3 to scan the original, 9 is a clutch for transmitting the driving force of the stepping motor to the driving pulley 7, and 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. Further, a gear 14 is fixed to one end of the rotating shaft of the clutch 100, and a pulley 15 is fixed to the other end. The drive shaft is connected to a pulley (not shown) fixed to the drive shaft.

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 configuration 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 2.3 in the six directions of the 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/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) for controlling 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; and 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 amount and speed of the stepping motor are controlled.

Next, the operation of the optical system drive device for a copying machine according to the present invention will be explained using the flowchart shown in FIG.

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 drive system using 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 a predetermined distance m1, that is, a distance corresponding to the document size, and then the stepping motor 8 is turned off and the optical system is stopped at the scanning end position. (#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 to the photosensitive drum (#7).Subsequently, the forward rotation clutch 9 is turned off, and the reverse rotation clutch 10 is turned on, the driving force of the main motor 44 is connected to the optical system, and the return of the optical system to the movement start position is started (#8).
. Then wait for the timing switch to turn on,
That is, after detecting that the optical system has returned to the movement start position, the reversing clutch 10 is turned off, and after stopping the optical system at the movement start position (#10), the main motor 46 is turned off. (#11), and ends the copy operation (#12>).

〔Effect of the invention〕

As explained above, according to the present invention, when the optical system is moved forward to project the document contents onto the photoreceptor, the optical system is driven by the stepping motor, and the scanning process that requires large torque and high speed movement is completed. Since the optical system is driven by the main motor during the subsequent return movement of the optical system, the drive source for the optical system can be simplified without reducing the copy speed. Furthermore, the structure is simplified and costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a side view of essential parts showing an optical system drive device of an image forming apparatus according to the present invention, FIG. 2 is a system configuration diagram of an image forming apparatus having an optical system drive device according to the present invention, and FIG. 3 is a flowchart for explaining the operation of the optical system driving device according to the invention. 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.

Claims (1)

[Claims] 1. In an optical system driving device of an image forming apparatus that reciprocates an optical system, the main motor, a stepping motor, a clutch that switches the driving force from the main motor and the stepping motor and transmits the driving force to the optical system, and Clutch switching control means for switching the clutch to transmit the driving force of the stepping motor to the optical system during the movement and switching the clutch to transmit the driving force of the main motor to the optical system during the backward movement. Features: Optical system drive device for image forming apparatus.