JPS5858559A - Controller for driving motor of electrophotographic copier - Google Patents

Abstract

PURPOSE:To reduce the capacity of an electric power source by controlling a driving motor for an optical scanning means synchronously while a motor contributing to copying is in operation, and driving said motor at the electric current below the intended value in the other prescribed period. CONSTITUTION:A photosensitive drum is rotated at a specified speed by a driving motor, and the speed thereof is detected by a speed detector 5 for the photosensitive drum. On the other hand, the number of revolutions of a motor 1 for driving an optical scanning means is controlled so as to keep the prescribed relation with the output of the detector 5 in accordance with said output. More specifically, the 1st switch 22 which changes the rotating direction of the motor 1, and the 2nd switch 26 which changes the speed of the motor in the stage of starting or inverting and in the stage of scanning cycle are provided. In the stage of starting or inverting the motor 1, the switch 26 is changed to the contact (a) side, by which the electric current of the motor 1 is controlled to a specified value. In the stage of scanning cycle, the switch 26 is connected to the contact (b) side, and the motor 1 is controlled according to the speed of the photosensitive drum.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive motor control device for an electrophotographic copying apparatus, and includes a motor control device 41 for driving a document illumination optical system or a movable document table of the electrophotographic copying device. , relates to a control device for a drive motor that repeatedly rotates in reverse.

An electrophotographic copying apparatus uses an electrophotographic photoreceptor having a photoconductive layer on its outer periphery. After uniformly charging the surface of this photoreceptor, an original image is projected, thereby creating a static image corresponding to the original. Layer the electro-a image.

Then, this electrostatic reservoir is converted into toner by a developer, and the toner image formed on the surface of the photoreceptor is further transferred to the surface of copy paper to obtain a copy image.

Normally, in this type of copying device, the photoconductor is cylindrical and is pivotably supported near the center of the device so that the photoconductor can be rotated. An optical device for projecting, a developing device for developing an electrostatic latent image corresponding to the original image formed on the surface of the photoconductor, a transfer device for transferring the toner image developed by the developing device 1 onto copy paper, and after transferring the toner image. A cleaning device and the like for removing toner images remaining on the surface of the photoreceptor are sequentially arranged around the cylindrical photoreceptor, that is, the photoreceptor drum.

Furthermore, the transfer device (a copy paper supply device that feeds copy sheets one by one, and a fixing device for fixing the transferred toner image on the copy paper) are provided near the photosensitive drum.

Furthermore, when using a cylindrical photoreceptor as an optical device that projects the reflected light from the original onto the surface of the photoreceptor, it is not possible to project the entire surface of the original onto the photoreceptor at once. An optical scanning means is required to scan the image in a slit shape.

Therefore, in order to perform a copying operation, the photosensitive drum,
The means for feeding paper from the paper feeding device to the transfer device, the means for feeding paper from the transfer device to the fixing device, or the driving of the fixing device, etc. usually only need to be rotated in one direction. requires a back-and-forth motion to scan the document.

A schematic configuration of the photosensitive drum drive system and the optical scanning means drive system is shown in FIG. 181. In the figure, 1 is a motor for driving the optical scanning means, 2 is a speed detector of the motor 1 for the optical scanning means g*, % is a timing belt, 4 is a photoconductive drum,
5 is a speed detector for the photosensitive drum 4, 6 is a motor for driving the photosensitive drum, 8 is a scanning optical system, and 8 m is a switch.

The photoconductor photosensitive drum 4 is rotated at a constant speed by a drive motor 6 via a gear chain or the like. The rotation of the photoconductor photosensitive drum 40 is detected by a photosensitive drum speed detector 5 consisting of an encoder and a light emitter/receiver.

On the other hand, the rotational speed of the optical scanning means driving motor 1 is determined based on the rotation of the photoconductor photosensitive drum 4 by a method described later - that is, the speed of the photosensitive drum is detected! Based on the output of a5, it is controlled to have a predetermined relationship therewith.

In addition, in FIG. 1, the scanning optical system 8 is reciprocated between IJ Mitswitches 8m and 8b.

When the scanning optical system 8 moves in the direction of arrow a, it is a copying cycle. Further, when moving in the direction indicated by the arrow, it is a return (return t@) cycle, and at this time, it is not directly involved in copying.

1121i! II is the speed (rotation number) of the optical scanning means driving motor 1, and the excess (-rotation number) of the photoconductor photosensitive drum 4.
FIG. 3 is a block diagram of a speed control circuit for controlling according to K; In Figure X, the same symbols as in Figure 11 represent the same or equivalent parts.

Reference numeral 9 denotes a divider that frequency-divides the output pulse of the photosensitive drum speed detector 5 to generate a speed reference pulse. .

The frequency division ratio of the splitter is set according to the degree of uniformity of the scanning optical system. It can be set or switched as appropriate from 9AK.

10 is a detection output pulse of the optical scanning means driving motor speed detector 2 supplied via the buffer amplifier 15;
The splitter 9 is a phase comparator that detects the phase difference with the output speed reference pulse and outputs a phase difference signal.

11 is a pulse signal obtained by adding a deaf output pulse detected by the optical scanning means driving motor speed detector 29 supplied via the buffer amplifier 14V to the output of the phase comparison 51G, that is, the phase difference signal, and converted into a DC signal. speed a
LPF (low pass filter) that generates a (DC) signal
It is.

12 is the triangular wave output from the triangular wave oscillator 15 and the L
A driver 1 receives the output of PFll and outputs a motor drive current with a pulse width corresponding to the output level of the LPF.
There are 2 circuits.

As is clear from FIG. 2 and the above description, in the scan cycle during the copying process, the optical scanning means, that is, the driving motor 1 of the scanning optical system 8 operates at a predetermined speed according to the constant rotation of the photosensitive drum 4. It is rotated synchronously with this in the forward direction at a constant speed.

On the other hand, in the return cycle of copying, the driving motor 1 must be reversed to return the scanning optical system 8 to the Bauhm hodgepodge. At this time, in order to increase the copying speed, efforts have been made to improve the starting and reversing characteristics of the IIIWe optical scanning means J [driving motor].

That is, by causing the motor to consume a large amount of power, for example, when starting the driving motor of the optical scanning means or when reversing from the scan cycle to the ty91-on cycle, the starting and reversing characteristics are improved and the copying process is improved. Speed - ie copy speed was improved.

This state will be explained with reference to FIG. III 5 I
t is a waveform diagram showing temporal changes in the average terminal voltage (dotted chain! I) and current (solid line) applied to the optical scanning means driving motor IK, and the speed of the motor 1 (dotted line).

The period indicated by TA in tf knee, 1K5FIIlt2 is the scan cycle of the copying machine, and the period indicated by TB is the return cycle.

As can be seen from this figure, at the beginning of the scan cycle TA, that is, when the motor is started, and during the return cycle 〒B, a high voltage is applied to the motor and a large current is supplied. This increases the acceleration when starting the motor, shortens the time until the start of the scan cycle, and speeds up the return speed of the scanning optical system 8 in the return cycle.

However, with the conventional method described above, the motor starts and
Since a large current must be applied to the motor during reversal, the required power supply capacity increases, and the motor driver also needs to have a large capacity. Therefore, it has been necessary to significantly increase costs in order to improve the starting and reversing characteristics of the motor.

Further, due to variations in constants such as the winding inductance of the motor, variations occur in the number of rotations during startup and reversal, and the adjustment thereof requires a lot of effort.

The purpose of the present invention is to improve the above-mentioned drawbacks and improve the above-mentioned drawbacks. It is an object of the present invention to provide a driving motor control device for an electrophotographic copying apparatus that can reduce the power source capacity and not cause variations in the number of rotations.

In order to achieve the above object, the present invention synchronously controls the motor for driving the optical scanning means when the motor involved in copying is activated, while the motor for driving the optical scanning means is synchronously controlled when the motor involved in copying is activated and reversed. The current is controlled at a constant current or at 5K so as not to exceed the planned current. Furthermore, the control circuit is simplified by sharing a part of the circuit for both types of control.

The present invention will be explained in detail below with reference to the drawings. Fourth
The figure is a block diagram of one embodiment of the present invention. In the figure, the same reference numerals as in Figure 182 represent the same or equivalent parts.

20 is a motor current detector that detects the current of the drive motor 1 and outputs a motor current signal; 22 is an N1 changeover switch for switching the rotation direction of the drive motor 10; its contact a is grounded; Connected to power supply voltage VCC.

This first changeover switch 22 is switched according to the ON/OFF state of the limit switches 8m and 8b shown in FIG. IE1, and reverses the rotational direction of the drive motor 1.

21 generates an output at the terminals 〒, ~T4 according to the connection position of the first changeover switch 22, and outputs the output from the transistors Trl~Tr.
This is a logic circuit that controls the on/off state of the drive motor IK and the direction of the current flowing through the drive motor IK, thus controlling the direction of its rotation.

By the way, this theory! The truth table for circuit 21 is shown in Table 1.

26 is a second changeover switch that switches the input to the comparator 23 at startup, return cycle, and scan cycle; contact a is switched at startup and return cycle;
@K * is connected and switched to contact b@ during the scan cycle.

24 and 25 are puffer amplifiers, and the output sum of the comparison 925th 111th transistor Trl and Tr4
The average current flowing through the drive motor IK is controlled, and the rotational speed of the motor 1 is thereby controlled.

I! As can be seen from Table 1, when the first changeover switch 22 is switched to all, the transistors Try and Try are turned on. Therefore, a current flows from the power source Wee through the transistor Try, the motor 1, the transistor Tr, and the current detection resistor 20. At this time, the buffer 24 is activated, and current control is performed via it as will be described later.

-Also, when the 1[1 changeover switch 22 is switched to bllK, the transistors Tr1 and Tr4 are turned on. Therefore, the motor current flows through the path of power supply Vce→transistor Tr4→motor 1→transistor Trl→current detection resistor 20, so that the direction of rotation of the motor is reversed.

At this time, the buffer 25 is activated, and current control is performed via these as described below.

Next, as described above, the second changeover switch 26 is switched to the contact 1 side when the motor 1 is started, reversed, or during a return cycle. Therefore, the output voltage of the motor current detection resistor 20 - that is, the motor current signal - is
In the comparator 25, triangular wave oscillation ls1! It is compared with the output of I.

Then, the conduction of the transistor Try is controlled according to the difference output, and the current of the motor 1 is controlled to a constant value.Alternatively, the current of the motor 1 may be controlled by 5KfI4 so that it does not exceed a predetermined value. It is possible.

Also, during the scan cycle, the second changeover switch 2
6 is connected to contact ba. The circuit configuration and operation at this time are exactly the same as the conventional example shown in FIG.

Therefore, when the present invention is applied, the temporal changes in the average motor applied voltage M (one-dot chain 1 m), motor current (actual M), and motor circuit speed (point #) are as shown in FIG. As is clear from this figure, the motor current is kept at a constant value in the return cycle.

Therefore, at 8A, the product of the motor current and voltage is constant. Therefore, assuming that the efficiency of the motor is constant, the return cycle time, that is, the return time and start-up time of the scanning optical system 8 in FIG. 1 will be constant, resulting in an advantage that variations will be reduced.

In addition, the maximum value of current supplied to the motor is smaller than that of conventional methods, so the capacity of the motor power supply is small.
Further, the capacity of the motor driver can be reduced, which has the advantage of reducing manufacturing costs.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a schematic configuration of a photosensitive drum drive system and an optical scanning means drive system in an electrophotographic copying apparatus, #I
Fig. 2 is a block diagram of one speed control path of the motor for driving the optical scanning means, Fig. 5 is a time chart showing the motor voltage current and rotational speed during motor speed control according to the prior art, and Fig. 4 is a diagram showing the speed control path of the motor for driving the optical scanning means. FIG. 5, which is a block diagram of an embodiment, is a time chart showing the voltage, current, and rotational speed of the motor during motor speed control in the present invention. '1...
Optical scanning means driving motor, 2... Optical scanning means driving motor speed detector, 5... Photosensitive drum speed detector, 8... Scanning optical system, am, 8b... Lint switch, 9 ... Frequency divider, 10... Phase comparator, 11-LPFC low-pass filter), 12.
...driver circuit, see...triangular wave oscillator, 14
．． 15.24.25...Buffer amplifier, 20...
Motor current detector, 21... Brass ma road agent patent attorney Michi Hiraki 1 non-person 15 Megin 31g

Claims (1)

[Claims] c! ) A $1 motor rotated at a predetermined constant speed, a first means for driving the a[2 motor for a predetermined period in synchronization with the rotational speed of the Is1 motor, and a first means for driving the a[2 motor for a predetermined period except for the predetermined period; The second motor drives the motor with a current lower than the planned value.
1. A driving motor control device for an electrophotographic copying device, characterized in that it comprises means. ←) The 111 motor rotates at a predetermined constant speed, and the
means for generating a reference pulse signal proportional to the rotational speed of the motor; means for generating a reference pulse signal proportional to the rotational speed of the second motor; and means for generating a reference pulse signal proportional to the rotation speed of the second motor; means for outputting a current signal; means for reversing the direction of lj1 rotation of the Ki2 motor; means for adding a speed pulse signal to a phase difference signal between the reference pulse signal and the speed pulse signal to obtain a speed target signal; a changeover switch that selects the speed target signal during the period and selects the motor current signal during the period other than the predetermined period; and a changeover switch that selects the motor current signal during the period excluding the predetermined period; 1. A drive motor control device for an electrophotographic copying device, comprising: means for controlling a current flowing through the electrophotographic copying device.