JPH0667245B2 - Control method for abnormal speed of copier optical system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for controlling a speed abnormality in an optical system movable copying machine.

<Prior Art and Its Defects> In an optical system moving type copying machine, since the feed speed of the optical system must be constant, for example, the pulse width or pulse period of the pulse obtained by attaching a rotary encoder or the like to the motor rotation shaft is used to determine the optical The moving speed of the system is detected, and the motor drive current is controlled so that the detected moving speed becomes constant. However, in the past, the motor drive current was unconditionally controlled by the feedback system at any point during the feed or return of the optical system.Therefore, if the optical system is locked for some reason, etc. There has been a problem that the load torque rapidly increases and a large current flows, and the motor coil burns out.

<Object of the Invention> The object of the present invention is to solve the above-mentioned drawbacks and to automatically brake a motor so that the optical system does not run away when the motor is overloaded due to a locked state of the optical system or the like. It is an object of the present invention to provide a control method for an abnormal speed of an optical system of a copying machine, which is possible.

<Structure and Effect of the Invention> The present invention detects the abnormal current by comparing the motor drive current value with a reference value by controlling the rotation speed of the motor for driving the optical system by controlling the pulse width of the motor drive current. When the generation time or the number of generations of the abnormal current is equal to or larger than a predetermined value, the pulse width of the motor drive current is gradually changed to gradually reduce the motor rotation speed and stop the motor rotation speed.

According to the present invention configured as described above, when the motor load becomes very large due to optical system lock or abnormal friction, it is detected that the motor drive current suddenly increases. Since the rotation speed is gradually decreased and stopped, abnormal speed can be detected easily and surely, and burnout of the motor coil and destruction of electronic parts due to overcurrent can be prevented. Further, since the abnormal stop is performed only when the generation time or the number of generation of the abnormal current is a predetermined value or more, malfunction due to noise or the like can be prevented. Furthermore, if the motor control current is suddenly turned off when a motor abnormality is detected, the optical system runs out of control due to the inertia of the motor and the optical system, exceeding the normal movement range and colliding with a holding member at the end (not shown) of the rails 32, 35. However, in the present invention, when a speed abnormality is detected, the motor rotation speed is gradually decreased to stop the motor. Therefore, a double failure due to a runaway of the motor and the optical system is caused. Can be prevented.

<Embodiment> FIG. 2 is a schematic structural diagram of a copying machine in which the speed abnormality control method according to the present invention is implemented. A photoconductor drum 2 is arranged substantially in the center of the copying machine main body 1, and a charging device, a developing unit, a transfer device, a static eliminator and the like are arranged around it. An optical system 3 including a zoom lens 30 that horizontally moves according to a set magnification is arranged above the photoconductor drum 2.
On the right side of the, there is a paper feed unit 4 including a paper feed tray and cassette loading unit.
However, on the left side, there are conveying units 5 and 2 for conveying the sheet after transfer.
A fixing unit 6 composed of individual rollers is arranged. An original cover 7 is rotatably attached to the upper portion of the copying machine main body 1, and an original corresponding to the original is formed on the photosensitive drum 2 by feed scanning of the optical system 3 by setting the original under the original cover 7. . The drive timing of the paper feed roller 40 that conveys the paper from the paper feed unit 4 toward the photosensitive drum 2 is controlled by the paper start clutch PSC in order to align the front end of the paper with the front end of the image on the drum. The on / off timing of the paper start clutch PSC is performed by the slave CPU for optical system control, which will be described later.

FIG. 3 is a perspective view of an essential part of the optical system 3 of the copying machine. In the optical system 3, the optical system scanning unit 31 that scans a document is a light source 31.
Mirror base MB1 that integrates a and two mirrors 31b and 31c
And a mirror base MB2 that supports a mirror 31d that reflects the reflected light from the document to the mirror 31b. These mirror bases MB1 and MB2 are horizontally slidably supported by two rails 32 and 33. One side portion 34 of the mirror base MB1 is fixed to the wire 35, and the wire 35 has an A or B position.
Both the mirror bases MB1 and MB2 move in the A direction (feed direction) and the B direction (return direction) according to the movement of the direction.
The wire 35 is wound around the pulleys 36 and 37 and the rotating shaft of the brushless DC motor 38, and the mirror bases MB1 and MB2 reciprocate according to the forward and reverse rotations of the motor 38.

The side 34 for fixing the wire of the mirror base MB1 is a vertical piece 3
A home position sensor HPS which has the vertical axis 34a and detects the vertical piece 34a is arranged in the stop area of the mirror base MB1. The stop area of the mirror base MB1 is a range from when the rear end portion C of the vertical piece 34a cuts the optical path of the home position sensor HPS to when it moves in the B direction (return direction) by about 10 mm. The position where the rear end C of the vertical piece 34a has moved by about ten and several millimeters past the set position of the home position sensor HPS becomes the mirror base MB1, that is, the stop position of the optical system.

In the copying machine of this embodiment, the control unit has a master CPU and a slave CPU.
It consists of and. The slave CPU receives signals from the home position sensor HPS, a rotary encoder RE (not shown) connected to the motor 38, and other sensors to control the rotation speed of the motor 38 and the paper start clutch PSC. FIG. 4 is a schematic block diagram of the control unit. The CPU is a master CPU (MCPU) 50 and a slave CPU (SCP
U) 51 and the MCPU50 sends a mirror start command and a mirror initial command to the SCPU51
PU51 sends status etc. to MCPU50. The MCPU50 receives signals from the input keys, various sensors, etc., and sends commands to the SCPU51 according to a program previously defined in the ROM52, receives status from the SCPU51, and controls various solenoids, main motors, and the like. SCPU51 is MCPU
In response to a command sent from 50, a signal from a sensor HPS, a rotary encoder RE, etc. is received according to a program pre-specified in the ROM 53, and the on / off timing of the paper start clutch PSC and the rotation speed of the main motor 38 are controlled. . Also, it is monitored whether the drive current of the motor 38 is an abnormal current, and when the abnormal current continues for a predetermined time or more or occurs a predetermined number of times, it is determined that the speed abnormality of the optical system has occurred, and the rotation of the motor 38 is determined. Gradually stop. After further performing a predetermined operation, the status or the like is transmitted to the MCPU 50.

FIG. 1 is a peripheral circuit diagram of the slave CPU.

The motor circuit is u, v, w three-phase DC brushless motor 38,
The rotary encoder RE includes a sensor S1 and u, v, and w phase detection sensors S2 to S4.
Output of the sensors S1 to S4 and home position sensor
The output of HPS is input to SCPU51 as signals A6 to A8. SCPU5
Signals A1 and A2 from 1 are set terminals S,
Input to each reset terminal R. The signals A1 and A2 define the set time and the reset time of the flip-flop 60, and the pulse width of the motor drive current is controlled by the signals. The signal A3 is a signal that determines whether the Q output of the flip-flop 60 is valid or invalid and is input to the gate 61. The signal A4 constitutes a code that determines the energization timing of each phase of u, v, and w, and is input to the gates 62 to 64 and the gates 68 to 70. Transistors 71-76 form a motor drive circuit,
ON / OFF control is performed according to the outputs of the gates 65 to 70. While the transistors 71, 74, 72, 75 are on, u phase, v
The phases are energized, and the v-phase and the w-phase are energized while the transistors 72, 75, 73 and 76 are on. By the code determined by the signal A4, these transistors to be turned on and off are switched, and they are energized in the order of uv → vw → wu → ... to form a rotating magnetic field.

The comparator 77 converts the current flowing in each transistor by a resistor 78, compares it with a reference value V _Z, and outputs it as a signal A5 to the SCPU 51. If the current is abnormal, the flip-flop 60 is forcibly reset. When the signal A5 goes "H", the SCPU51 knows that the motor drive current has become an abnormal current for some reason. Further, when the flip-flop 60 is reset, the Q output becomes "L", and the motor drive current immediately becomes 0.

Next, the operation of the SCPU 51 will be described with reference to FIGS. This figure is a flowchart showing the rotation speed control operation of the motor 38.

When the motor 38 enters the rotation start mode upon receiving a mirror start command or the like from the MCPU 50, first step n1
(Hereinafter, step ni is simply referred to as ni.)
Set to. As a result, the Q output of the flip-flop 60 becomes valid and is guided to the motor drive circuit.
Then, at n2, the outputs of the sensors S2 to S4 are read to detect the position of the rotor. According to the result, the on / off combination of each phase of u, v, and w is calculated by n3, and the code of the combination is output as the signal A4. Next, wait for the motor drive current off time TB calculated by the interrupt processing described later in n4 to elapse, and when that time elapses, signal A1 is output in n5.
To “H”. Then, at n6, wait until the motor drive signal ON time TA calculated by the interrupt process described later elapses, and during that time, test the signal A5 at n7 and wait for the time TA.
When has passed, the signal A2 is set to "H" by n8. N5 above
Then, when the signal A1 is set to "H", the flip-flop 60 is set, and the ON / OFF state of the transistor determined by the signal A4 is maintained during the setting period. When the signal A2 is set to "H" at n8 above, the flip-flop
60 is reset, and all the transistors are kept off during the resetting period. The test of the signal A5 in n7 determines whether or not the signal A5 is "H". If "H", that is, if the motor drive current is equal to or greater than the reference value, the internal counter is incremented.

After the above operation is completed, it is determined in n9 whether or not it has moved a predetermined distance. Home position sensor HPS
After receiving the output signal A6 of, the determination is made as to whether or not the vehicle has moved a predetermined distance to the stop position. At n10, it is determined whether the number of times the signal A5 becomes "H" by the test performed at n7 is a predetermined number K or more. If K or less, n2〜
The n9 is repeatedly executed to rotate the motor while inverting the flip-flop 60.

When the signal A8 is input from the sensor S1 attached to the rotary encoder RE during the above operation, the interrupt mode is entered, and n20 and below are executed. First, at n20, the rotation speed of the motor is calculated from the pulse cycle of the signal A8. Subsequently, in n21, the difference between the actual rotation speed and the target rotation speed is calculated. The target rotation speed (target speed of the optical system) is stored in the ROM 53 in advance. When the difference is detected in n21, the process proceeds to n22, in which the on time TA and the off time TB of the motor drive current for achieving the target rotation speed are calculated and the process returns. This TA and TB are n
It is used in 4, n6 and the motor speed is controlled to reach the target speed.

When n10 detects that the number of times that the signal A5 has become "H" has become equal to or greater than the predetermined value K, n11 to n13 are executed and abnormal stop is performed. First, at n11, the motor drive current on-time TA immediately before that is set to be shorter by ΔT. Subsequently, at n12, the flip-flop 60 is set and reset is controlled. As a result, the rotation speed of the motor 38 is forcibly reduced slightly. The processes of n11 and n12 are continuously executed until a fixed time elapses, and are stopped when the rotation speed of the motor becomes substantially zero. Since the MCPU50 has already received from the SCPU51 the status indicating that the abnormal speed has occurred at this stage, it performs an abnormal process such as displaying to the operator that the abnormal speed has occurred when the motor 38 stops. .

By the above operation, when a speed abnormality occurs, the motor rotation speed can be gradually reduced and stopped.

If the number of times A5 becomes "H" at n10 is K or less, normal stop is performed without proceeding to n11. Therefore, the case where the signal A5 becomes "H" due to noise or the like can be ignored. That is, it is possible to perform control that does not abnormally stop due to noise or instantaneous abnormal current. In this embodiment, the number of abnormal currents is counted to determine whether the number of abnormal current occurrences is equal to or more than a predetermined value, but the execution time from n2 to n9 is extremely short. Since it is time, it is also determined in n10 whether the occurrence time of the abnormal current is a certain value or more. Therefore,
The abnormal stop processing can be performed both when the abnormal current is generated for a long time or when the instantaneous abnormal current is generated many times. Further, in this embodiment, 3
A phase DC brushless motor was used, but a normal DC motor can also be used.

[Brief description of drawings]

FIG. 1 shows a peripheral circuit diagram of a slave CPU of a copying machine in which the present invention is implemented. FIG. 2 is a schematic configuration diagram of the copying machine, FIG. 3 is a partial external perspective view of an optical system, and FIG. 4 is a schematic block diagram of a control unit. FIG. 5 is a flowchart showing the motor rotation speed control operation of the SCPU. 2 ... Photosensitive drum, 3 ... Optical system, HPS ... Home position sensor, RE ... Rotary encoder, 38 ... Motor. 77 …… Comparator, V _Z …… Reference voltage.

Front page continued (72) Inventor Yasumasa Oba, 3744 Ooka, Oka, Numazu City, Shizuoka Prefecture, Japan Electric Machinery Co., Ltd. (72) Inventor, Mitsuhiro Matsuoka, 3744, Ooka, Numazu City, Shizuoka Prefecture, Japan (56) References 55-93165 (JP, A) Actually opened 56-49904 (JP, U)

Claims (1)

[Claims] 1. A rotation speed of a motor for driving an optical system is controlled by controlling a pulse width of a motor drive current, and the motor drive current value is compared with a reference value to detect whether or not the current is an abnormal current. When the time or the number of times of occurrence is equal to or more than a predetermined value, the pulse width of the motor drive current is gradually changed to gradually reduce the motor rotation speed and stop the motor rotation speed. .