JPS6321664A - Control method for power source in electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To suppress the load current of a DC power source and to reduce a load on the power source, and to decrease the capacity of the DC power source by interrupting or reducing the current from the DC power source at the time of the operation switching or the actuation of a DC driving source. CONSTITUTION:When a device is started, a motor control circuit 33 supplies the motor current from the DC power source 25 to a DC motor 23 as the DC driving source in response to the output of a motor driving circuit 32 to rotate the motor 23. In such case, the peak current of the motor 23 is conducted only for a limited time at the time of the operation switching or starting, etc., so the current of a drum heater 8 is interrupted for reduced only when the peak current is conducted, thereby reducing the maximum load current of the power source 25. Namely, when the motor 23 is braked or reversed, the heater current supplied to the heater 8a from the power source 25 is interrupted or reduced to suppress the load current of the power source 25 and lighten the load on it, thereby reducing the capacity of the power source 25.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for controlling a power supply in an electrophotographic copying machine.

(Prior art 1) Recently, in electrophotographic copying machines, the control l! In order to simplify the process, more and more devices are being driven by DC power instead of devices driven by AC Nai. As the number of such devices increases, the overall DC power consumption also increases, and a DC power supply with a large output capacity is required.

The output capacity of this DC N source is set by adding the current value flowing through each device, and the DC power source is arranged within a limited space within the copying machine.

However, when the output sound M of such a DC power source is increased, the heat generation of the circuit elements also increases, and accordingly, it is necessary to increase the size of the heat sink or perform forced cooling with a fan, etc. There is a tendency for the external size of the DC power source to become large, which takes up a lot of space inside the copying machine, making it possible to reduce the size of the copying machine by 7N.

In addition, in the above-mentioned DC power supply, it is difficult to realize the desired power design and thermal design in a limited space by simply determining the load current by considering the sequence, and some other measures are required.

(Objective of the Invention) The present invention solves the above-mentioned technical problems, suppresses the load current of the DC power supply that drives the equipment provided in the electrophotographic copying machine, reduces the burden on the power supply, and reduces the burden on the DC power supply. υl'j11 of the power supply in an electrophotographic copying machine that can be
The purpose is to provide a method.

(Structure of the Invention) The present invention provides for cutting off or shutting off power from the DC power source supplied to other DC loads when switching or starting up a DC drive source driven by a DC power source provided in an electrophotographic copying machine. It lowers the

With this configuration, when switching operations or starting up the DC drive source, power to other DC loads is cut off or reduced, and the load current of the DC N source is unlikely to increase.

(Embodiment) FIG. 2 is an overall configuration diagram of an electrophotographic machine adopting the υ1111 method of power supply of the present invention.

In FIG. 2, a contact glass 2 on which a document is placed is provided at the top of a housing 1 of an electrophotographic copying machine.
A document holder 3 is disposed above the contact glass 2. Inside the housing 1, there are a document irradiation lamp 4, a reflector 5, and a mirror 5a.

6b, 6c, 6d, and a lens assembly 7,
These constitute the optical system. A photosensitive drum 8 that receives light from this optical system A and has a heater 8a inside.
A main charging device 9 including a corona discharger, a developing device 10, a transfer device 11, a separating device 12, a cleaning device 13, etc. are arranged around the main charging device 9 in the rotating direction in this order. The heater 8a is provided to prevent condensation on the photosensitive drum 8 and to take advantage of the characteristics of the photosensitive member. An exposure area from the optical system A is provided on the photosensitive drum 8 between the main charging device 9 and the developing device 10.

The developing device 10 has a developing roller 10a, which supplies toner powder onto the photoreceptor drum 8, and develops the electrostatic latent image formed by the exposure into a toner image. Furthermore, a transport path is formed by a pair of transport rollers 14 for transporting the copy paper to the transfer device N11 and a guide plate 15 for guiding the copy paper sent by the transport rollers 14 to the transfer device 11. A copy paper cassette 17 is set upstream of the conveyance roller 14, into which copy paper is sent out by a paper feed roller 16. In addition, the transfer device 1
1 electrostatically transfers the developed toner image formed on the photoreceptor drum 8 onto the copy paper conveyed by the conveyance roller 514, and the separating device 12 is a corona discharger or the like, and the toner image after the transfer is transferred. This is for peeling the copy paper from the photoreceptor drum 8. A conveying roller 18 is provided on the downstream side of the separating device 12 in the copy paper conveying direction, and a fixing device 20 having a heat roller 19 is provided on the downstream side of the fixing device 20. A tray 22 for receiving copy paper is set. Further, a fan motor 24 for cooling the inside of the housing 1 is provided in the housing 1 of the electrophotographic copying machine.

The direct current 'am25 is the drum heater 8a of the photosensitive drum 8,
It supplies DC power for driving the main charging device 9, the developing roller 10a of the developing device 1o, the transfer device 11, the separating device 12, the DC motor 23 for driving the optical system A, and the like. Note that the main motor for driving the document irradiation lamp 4, the transport roller 14, the paper feed roller 16, the heater of the heat roller 19, the fan motor 24, etc. are driven by an AC power source.

FIG. 1 is a block diagram of a power supply device that employs a power supply control method for an electrophotographic copying machine according to an embodiment of the present invention.

This embodiment controls the power supplied to an electrophotographic copying machine so as to reduce the current consumption of the device while satisfying the operation of the device (driven by a DC electric IT!25) as much as possible. In particular, the drum heater 8a of the photosensitive drum 8 and the DC motor 23 that drives the optical system A consume more current than other devices, so we focused on this and tried to reduce the current consumption of the entire device. It is something. In addition to such devices, there are solenoids for driving and stopping mechanisms for rotating the conveyance rollers 14, 18, etc., but such solenoids only flow a current of about 100 mA, for example. Also, since the solenoid operates intermittently, the average current consumption of the solenoid is considerably smaller than that of the drum heater 8a, for example.

By the way, the current consumption of the drum heater 8a is, for example, 2.3
For example, 80 W of power is required to operate the drum heater 8a and the DC motor 23 at the same time, and if the power to drive multiple other loads is also included, the rated capacity f
A DC power supply 25 of about f1170W is required. Therefore, in order to reduce the rated capacity of the DC power supply 25, it is possible to reduce the peak current of the DC motor 23. However, if the peak current is reduced, the DC motor 23 will start up more slowly during startup, braking, reversing, etc. As a result, the rising speed of the optical system A becomes slow, and the copying efficiency decreases. Therefore, the peak current of the DC motor 23 cannot be reduced.

Therefore, in this example, we use DC drive! The peak current of the DC motor 23 as a source flows only during limited times such as during startup, braking, and reverse rotation, so the drum heater (corresponding to other DC loads) is only used when the peak current flows.
8a is cut off, and the maximum load current of DC 1!25 is reduced.

Note that since the drum heater 8a is wrapped around the photosensitive drum 8, even if the heater current is cut off for a short time, there is almost no change in the temperature of the photosensitive drum 8, and the characteristics of the photosensitive drum are not affected, so there is no problem. .

Continuing the explanation in FIG. 1, the optical system position sensor 30
Detects the position of the optical system A with respect to the contact glass 2 and provides the processing circuit 31 with the position information. The motor drive circuit 32 operates a motor control circuit 33 in response to a motor drive signal from the processing circuit 31, and controls the rotation of the DC motor 23. The device 34 represents the aforementioned solenoid, a switch necessary for controlling the device, and the like, and the output of this device 34 is given to the processing circuit 31 via the I10 port 35.

The line e1 where the input end of the heater drive circuit 36 and the output end of the processing circuit 31 are connected is pulled up to 5V by the resistor R1, and the heater drive circuit 36 receives the heater drive signal from the processing circuit 31 via the line e1. It is something you receive.

The heater control signal generation circuit 37 includes a transistor Tr and resistors R2 and R3, and provides a heater control signal to the heater control circuit 38 in response to the output of the heater drive circuit 36 to control the current flowing through the drum heater 8a. It is something.

The processing circuit 31 creates various signals as described later using the machine clock as a basic timing, and performs processing operations.

FIG. 3 is a timing chart for explaining the operation of the above embodiment.

Figure 3(a) shows the S/D (stop/drive) signal,
That is, it indicates a signal for stopping or moving the optical system A, and the high level of this S/D signal is a stop signal, and the low level thereof is a drive signal. Note that the period TO corresponds to the operation period for one copying operation of the original. Figure 3(b) shows the F/R (forward/reverse) signal, that is, the signal for moving the optical system A forward or backward.The high level of this F/R signal is the forward signal, and its low level is a reverse signal. Figure 3 (C) shows optical system A moving forward until it reaches a predetermined position @ (the position where it can read the maximum size original), then moving backwards and just before reaching the reference position (home position), optical system A moves forward. Indicates the FF (forward full) signal for applying the brakes. FIG. 3(d) shows the forward and reverse rotational speeds of the DC motor 23. FIG. 3(e) shows the motor current flowing through the DC motor 23 (shown as an absolute value). FIG. 3(f) shows the heater current flowing through the drum heater 8a.

The operation of the above embodiment will be explained with reference to this timing chart.

First, before the copying machine starts copying, the processing circuit 31 reads the position of the optical system A based on the output of the optical system position sensor 30, and when it determines that the optical system A is at the reference position, the processing circuit 31 reads the position of the optical system A as shown in FIG. ) A low level S/D position signal as shown in
data to the data drive circuit 32. This motor drive circuit 32 is
If a high level F/R signal is received from the processing circuit 31 while the low level S/D position signal is present, the motor control circuit 33 is operated to drive the DC motor 33.

That is, the motor control circuit 33 responds to the output of the motor drive circuit 32, and at time t1 when the S/D position signal falls, the DC power supply 25 supplies the DC motor 23 with a motor voltage 1 (period) as shown in FIG. 3(e). T1 current) is supplied. As a result, the DC motor 23 rotates at a rotational speed as shown in FIG. 3(d).

By rotating the DC motor 23 in this way,
When the optical system A reaches a predetermined position while irradiating the document, the optical system position sensor 30 provides a position signal to the processing circuit 31 indicating that the optical system A has reached the predetermined position. Thereby, the processing circuit 31 switches the F/R signal from high level to low level and supplies it to the motor drive circuit 32. The motor υ1'@circuit 33 switches the DC motor 23 to reverse rotation in response to the output of the motor drive circuit 32 at that time. The point in time at which the DC motor 23 is switched to reverse rotation is the falling point t2 of the F/R signal. The motor current (current shown in period T2) flows through the DC motor 23 which has been switched in reverse by the motor control circuit 33 as shown in FIG. 3(e), and the DC motor 23 flows as shown in FIG. 3(d). rotates in the opposite direction at a certain rotation speed.

By the way, the load current of the DC power supply 25 is about to increase due to the peak 'iR current 11 of the motor current when the DC motor 23 is started in reverse, but the processing circuit 31 does not drive the heater at the timing t2 of the fall of the F/R signal. A heater current stop signal is provided to circuit 36.

At that time, the heater drive circuit 36 turns off the transistor Tr in the heater control signal generation circuit 37, for example, and operates the heater control circuit 38. As a result, the heater control circuit 3
8 cuts off the heater current flowing from the DC power supply 25 to the drum heater 8a (shown as a low level) as shown in FIG. 3(f).

Therefore, the load IR current of the current power source 25 is unlikely to increase because the heater current flowing to the drum heater 8a is cut off at the time when the peak current 11 of the motor current is about to flow.

Due to this operation, the DC motor 23 reverses, and the optical system A moves backward toward its original position, that is, the reference position. When the optical system A reaches the vicinity of the reference position, the processing circuit 31 moves the optical system A at the reference position. In order to stop the motor, an FF signal as shown in FIG. 3(C) is sent to the motor drive circuit 32 as a brake signal.
give to The motor control circuit 33 applies a motor current of period 11T3 as shown in FIG. 3(e) to the DC motor 23 in order to decelerate the optical system A in response to the output of the motor drive circuit 32 that has received the FF signal. . Note that the motor current during period T3 is for braking the DC motor 23, so it is a current in the opposite direction to the motor current flowing during period T2.

Due to such braking of the DC motor 23, the optical system A moving toward the reference position is decelerated, and when the optical system A reaches the reference position, the processing circuit 31 receives the reference position detection signal from the optical system position sensor 30. , in response to that, Figure 3 (a
) is applied to the drum drive circuit 32 to control the motor current to be cut off at the rising time t3 of the pulse, and a heater drive signal is applied to the heater drive circuit 36 to control the drum drive circuit 32. The heater 8a is controlled to flow the heater N flow again.

In this way, the processing circuit 31 controls the peak current 11 during the reverse rotation of the DC motor 23 that occurs during the period T2 and when the DC motor 23 brakes (at the time of braking) that occurs during the period T3, as shown in FIG. 3(e). During the period T4 including the peak current 11 generated in the drum heater 8a, as shown in FIG.
control to cut off the heater current flowing to the

Note that the F/R signal as shown in FIG. 3(b) is
The D position signal becomes high level at rising time t3, and is output from the processing circuit 31 as a condition signal to advance the optical system A in the next copying operation, that is, to rotate the DC motor 23 in the forward direction, and is outputted from the processing circuit 31 to the motor drive circuit 32. given to.

According to the above embodiment, the DC motor 2 as a DC drive source
By cutting off the heater current from the DC power supply 25 supplied to the drum heater 8a at the time of rotation switching or at the time of starting t11, that is, at the time of braking or starting the reverse rotation,
Since the load current of the DC power source 25 can be significantly reduced compared to when the heater current is constantly flowing, the output capacity of the DC power source 25 can be reduced.

In the above embodiment, the heater N flow is cut off during the period T4 shown in FIG. 3(f), but the heater current is not limited to this, and the heater current may be controlled to be reduced.

(Effects of the Invention) As described above, according to the present invention, when switching or starting the operation of a DC drive source driven by a DC power source in an electrophotographic copying machine, the DC power source supplied to other DC loads is By cutting off or reducing the power, more current flows than in the steady state when switching or starting the DC drive source, but at the same time, other M
l Since the power supplied to the load is cut off or reduced,
The load current of the DC power supply is suppressed, the burden on the power supply is reduced, the thermal design of the power supply becomes easier, the heat dissipation means can be made smaller, and the rating of the element can also be lowered. An inexpensive DC Li source can be used, and the size and cost of the copying machine can be reduced accordingly.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a power supply control device employing a power supply control method for an electrophotographic copying machine according to an embodiment of the present invention, FIG. 2 is an overall configuration diagram of the electrophotographic copying machine, and FIG. 5 is a timing chart for explaining the operation of the power supply control device. 8a...Drum heater (other DC load), 23.
...DC motor (DC drive source), 25...DC power supply,
30... Optical system position sensor, 31... Processing circuit, 3
2... Motor drive circuit, 33... Motor control circuit,
34...device, 35...-110 boat, 36...
... Heater drive circuit, 37 ... Heater control signal generation circuit, 38 ... Heater tIIIM1 circuit.

Claims (1)

[Claims] 1. At the time of operation switching or startup of a DC drive source driven by a DC power supply provided in an electrophotographic copying machine, cutting off or reducing power from the DC power supply supplied to other DC loads. 1. A method for controlling a power supply in an electrophotographic copying machine, characterized in that: 2. The DC drive source is a DC motor that drives an optical system, etc., and the power from the DC power source supplied to the DC load is cut off or reduced when the rotation of the DC motor is switched or started. A method for controlling a power supply in an electrophotographic copying machine according to claim 1. 3. A patent claim characterized in that the DC load is a heater for the photoconductor, and when switching or starting the operation of the DC drive source, power from the DC power source supplied to the heater is cut off or reduced. A method for controlling a power supply in an electrophotographic copying machine according to item 1.