JPH0593966A - Optical system drive - Google Patents

Abstract

(57) [Summary] [Object] In a copying machine using a scanning optical system in which a plurality of scanning speeds can be set, the acceleration time at the start of scan drive of the optical unit is made substantially constant for a plurality of scanning speeds. An object of the present invention is to stabilize the vibration characteristics of the optical unit at the time of drive start-up in a good state by using the control device for the drive motor. [Structure] The optical unit 17 is driven by a servo motor 13. The servo motor 13 is driven by a control device composed of the CPU 11 and the servo driver 12. Even if the scanning speed is changed in the CPU 11, a stable drive characteristic can be obtained by providing a structure having a control function for keeping the drive rising acceleration time substantially constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning optical system driving device such as a copying machine using a scanning optical system.

[0002]

2. Description of the Related Art As a typical example of a copying apparatus using a scanning optical system, its structure will be described with reference to FIGS. A wire 15 is attached to the optical unit 17, and the wire 15 is connected to the servo motor 1 via the wire drum 14.
It is driven by 3. The servo motor 13 is driven by a control device including a CPU 11 and a servo driver 12.

The copying apparatus having the above-mentioned structure generally has a function of changing the scanning speed of the optical unit to a speed corresponding to each magnification, mainly for changing the copying magnification. Here, in order to reduce the load on the drive motor when accelerating the optical unit to each of the above scanning speeds, a method of accelerating to a scanning speed from a low speed over a certain acceleration time is adopted. At the time of scan drive start-up acceleration, due to the elasticity of the optical unit 17, the wire 15 and the like, vibration is generated relative to the target speed after the acceleration time, and a deviation amount of the speed is generated. This vibration will eventually be attenuated and settled, but if the settling characteristics deteriorate, the copy image will deteriorate. In order to reduce the size of the copying apparatus and improve the image quality, it is necessary to improve the settling characteristics.

Conventionally, in the CPU 11, the drive speed time table which is always referred to when the optical unit is driven has only one kind of speed gradient curve at the time of acceleration, and the acceleration time according to the gradient curve. Accelerate to different speeds depending on whether you take short or long. FIG. 2 shows changes in the servo motor drive speed when the conventional scanning speed is changed.

At this time, the acceleration time changes according to the scanning speed.

[0006]

When the optical system is driven, the vibration settling characteristic is closely related to the acceleration time, and the acceleration time for improving the settling characteristic exists as a value peculiar to the optical unit driving system. It is desirable to fix it to that value. However, the conventional technique has a problem that the acceleration time cannot be kept constant because the acceleration time changes according to the scanning speed.

[0007]

In order to solve this problem, the drive system of the present invention uses a CPU used in a conventional optical system drive apparatus to accelerate the drive start even if the scanning speed is changed. It has a configuration incorporating a CPU having a control function of keeping time substantially constant.

[0008]

With this configuration, the acceleration time determined by the CPU is fixed to a good value for the rise settling characteristic regardless of the magnification, so that the optical system drive rise settling characteristic can be stabilized in a good state, and the copier performance can be improved. Image quality and miniaturization can be realized.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1A, 11 is a CPU, and 12
Is a servo driver, 13 is a servo motor, 14 is a wire drum, 15 is a wire, 16 is a pulley, 17 is an optical unit, 18 is an output signal, and 19 is a feedback signal. The figure (b) shows the speed-one-hour characteristic diagram.
23 to 23 are velocity curves when the scanning velocity is changed, and t is the acceleration time.

The operation of the optical system driving device configured as described above will be described with reference to FIGS. 1 and 2. FIG. 2 is a speed curve when the scanning speed is changed in the conventional driving device. As the speed driving table during acceleration in the CPU, a single speed gradient curve stored and stored in the memory is referred to at any scanning speed. . Therefore, when the copy magnification is changed, that is, when the scanning speed is changed, the acceleration time of the speed curve increases or decreases. FIG. 1B is a speed curve during acceleration by the driving device according to the present invention. As the copying magnification is changed, the speed gradient is calculated and changed in the CPU so as to keep the acceleration time constant. Therefore, the acceleration time can be kept constant irrespective of the copy magnification, and the oscillation settling time can be shortened by adjusting the acceleration time to a time with good settling characteristics of the optical system rising vibration, and therefore, The copying machine can be downsized and the image quality can be improved. Although a servo motor is used in FIG. 1, it goes without saying that a stepping motor may be used.

[0012]

The driving device according to the present embodiment improves the settling characteristics of the rising edge, and is excellent in terms of high image quality and downsizing of the copying machine.

[Brief description of drawings]

FIG. 1A is a configuration diagram of an optical system driving device according to a first embodiment of the present invention, and FIG. 1B is a velocity curve diagram at the time of driving the optical system when changing a copy magnification in the first embodiment.

FIG. 2 is a velocity curve diagram at the time of starting the optical system when changing the copy magnification in the conventional optical system driving start-up device.

[Explanation of symbols]

 11 CPU 12 Servo Driver 13 Servo Motor 14 Wire Drum 15 Wire 16 Pulley 17 Optical Unit 18 Output Signal 19 Feedback Signal 21, 22, 23 Scanning Speed Changing Speed Curve 31, 32, 33 Scanning Speed Changing Speed Curve

Claims (1)

[Claims] 1. A vibrating characteristic at the time of driving start of an optical unit is improved by using a control device of a drive motor which makes an acceleration time at the time of scanning drive start of an optical unit substantially constant for a plurality of scanning speeds. An optical system driving device characterized by being stabilized by.