JPH0451260A - Copying device - Google Patents

Abstract

PURPOSE:To prevent a device from being started again when a leak occurs and also to inform of the occurrence of the leak by providing a nonvolatile memory for recording the control history of a control circuit for turning off a relay which is provided on an AC line in the case of detecting a current exceeding a reference level on the AC line for supplying a power. CONSTITUTION:In a leak break circuit 300, the difference between a going current and a returning current which conduct on the AC line 100 is detected by a current difference detecting means 310, and in the case that the current value of a detection circuit 320 connected with the detecting means exceeds the reference level for a time equal to or longer than a prescribed time, the circuit of an AC load 140 is opened and closed through relays 111 and 112 by a controlling signal from a microprocessor 340. A RAM 220 in a process control circuit 200 for performing an image forming processing is the nonvolatile memory for holding a recorded content even in the case of turning off a power source, and also for storing the history of the copying device, the situation of the leak occurrence and the situation when thermorunaway occurs in a fixing device. The image forming processing is started by a microprocessor 210, and also the history information from the RAM 220 is read, the leaking state is detected, a leak error message is displayed on a display part 260 and the device action is stopped by the microprocessor 210.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an earth leakage cutoff circuit that detects electric leakage in an AC line of a copying machine and shuts off the AC line.

[Conventional technology]

The AC line in the copying machine is naturally connected to an AC power source that supplies AC power. The AC line is connected to a DC power source such as an approximately 5V low-voltage power supply unit that drives a control circuit, etc., an AC load such as a fixing lamp of a fixing device, an exposure lamp, etc., and a driver that drives the AC load or DC load. . Furthermore, in addition to the control circuit, a plurality of DC motors, solenoids, etc. are connected to the DC source to supply DC power. As described above, the control circuit is driven by DC power and controls the driver to drive and control the AC load and the DC load. In particular, loads that derive their two-handed power directly from the AC line are at risk of catching fire due to a ground fault. Therefore, the present inventor has developed a copying machine equipped with an earth leakage cutoff circuit that prevents ground faults from occurring.

[Problems to be solved by the invention]

However, even if the copying machine is stopped due to the activation of the earth leakage cutoff circuit, the cause of the copying machine's stoppage cannot be recognized, and the
If restarts are repeated, there is a problem in that there is a risk of electrical leakage. SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a copying apparatus that prevents restarting when a current leakage occurs and has a function to notify the user of the occurrence of a current leakage.

[Means to solve the problem]

The present invention that achieves the above object includes a current difference detection means for detecting a current difference between AC lines that supply power from an AC power supply to a load, a detection circuit connected to the current difference detection means, and a detection circuit connected to the current difference detection means. A copying machine is provided with a control circuit that detects a current that continuously exceeds a reference level and turns off the relay provided in the AC line I, and is provided with a nonvolatile memory that records the control history of the control circuit. This is a characteristic feature.

【Example】

Next, embodiments of the present invention will be described based on the accompanying drawings. FIG. 1 is a block diagram showing an embodiment of an AC line and a DC line in a copying machine equipped with an earth leakage interrupting circuit according to the present invention. The copying apparatus of this embodiment has various loads connected to an AC line 100, and when an image forming process is executed by a process control circuit 200, both are equipped with an earth leakage cutoff circuit 300.
It has a function to monitor electric leakage in the AC line 100 and prevent electric leakage accidents, and in particular, after stopping the start-up due to the occurrence of electric leakage, it has a function to prevent restart by turning on the power and to display the occurrence of electric leakage. . The configuration of each part of the copying apparatus will be explained below. First, the connection relationship of the AC line 100 will be described. an AC line 100 connected to an AC power supply 101; a high voltage power supply unit l-120 connected to the AC line 100;
An AC load 140 is connected via a low voltage power supply unit 130 and relays 111 and 112. In addition, the AC line 100 of this embodiment includes an earth leakage interrupting circuit 3.
00 is connected, and when a leakage is detected, the AC load 140 is connected.
The earth leakage cutoff circuit 300 detects the difference between the forward current and the return current as a current by a current difference detection means 310 by electromagnetic induction, and detects the difference between the forward current and the return current as a current by a detection circuit connected to the detection means 310. an amplification circuit 330 that amplifies and outputs the current flowing through 320; and a relay 111 that opens and closes the AC load 140 and the AC line 100;
．． A microprocessor 340 is connected to control the 112. The earth leakage interrupting circuit 300 detects the difference between the forward current and the return current flowing through the AC line 100 as a current by the current difference detection means 310 by electromagnetic induction, and the detection means 31
A circuit that opens and closes a circuit connected to an AC load 140 via a relay ill, 112 using a control signal from a microprocessor 340 when the detection circuit 20 connected to It is. The microprocessor 340 is equipped with an at cutoff routine that controls the relays Ill and 112 that connect and disconnect the AC load 140 from the AC line 100, and has different reference levels Sre.
The reference level generating means for generating the voltage V is provided. The microprocessor 340 also includes an analog input port for inputting analog signals, and the analog signals input to this port are converted from analog to digital to digital data consisting of 8 bits with 64 gradations. Execute the Kiri after that. This is an earth leakage cutoff routine. The earth leakage cutoff route is the detection circuit 320
A routine for controlling the opening and closing of the circuit to which the AC load 340 is connected by comparing the value of the current conducted to the reference level S rev set from the reference level generating means and determining whether it continues for a predetermined period of time. It is. The reference level generation means is an internal memory such as RAM or ROM that constitutes the microprocessor 340, and outputs a different reference level S rev depending on the input l signal from the timing generation means. In this embodiment, the reference level S rev is two pieces of data corresponding to 15 mA and 40 mA. The reference level generating means is one of the means constituting the earth leakage cutoff routine. Note that when the input signal does not exceed the reference level S rev for a predetermined period of time, the microprocessor 340 sends a low level control signal to the relays 111 and 112. The current difference detection means 310 is, for example, a zero-phase current transformer sensor (
(commonly known as ZCT, hereinafter simply referred to as ZCT),
A coil C is wound around an AC line 100,
If there is a difference between the going and returning current values in the AC line 100, a potential is generated at both ends of the coil C due to the action of electromagnetic induction. The detection circuit 320 includes a Z CT 310 and an amplifier circuit 330.
This is a circuit that connects the Z CT 310 and inputs the minute current generated in the Z CT 310 to the amplifier circuit 330. Amplification time! 330 is a circuit that amplifies a minute alternating current input signal to a predetermined level, specifically, to the optical level of the microprocessor 340, and further rectifies and outputs the alternating current signal. The relays 111 and 112 are, for example, thyristors, and are self-holding relays that, once conductive, maintain the conductive state until the next trigger occurs. Moreover, it is not limited to a thyristor, and an electromagnetic relay or the like may be used. Further, the relay is not limited to a self-holding type relay, and may be a non-self-holding type relay. Next, the high voltage power supply unit 120 and the low voltage power supply unit 1
The connection relationship of the DC lines consisting of 30 will be described. A high voltage DC load 230 is connected to the high voltage power supply unit l-120. A driver 23 is installed in the low voltage power supply unit 130.
0.250 and microprocessors 210 and 340 are connected. Although the low-voltage DC power supply 130 is not shown, the RAM 220 and the display unit 260 are also approximately 5
It supplies V DC power. The process control circuit 200 of this embodiment will be described below. The process control circuit 200 includes a microprocessor sensor 210
, RAM 220, drivers 230, 250, high voltage DC load 2401 and display section 260. The microprocessor 210 has drivers 230, 250
It is equipped with an image forming routine that performs the image forming process by driving the high voltage DC load 240, AC load 250, and low voltage DC load through the power source, etc., and stores the timing for starting each load in advance from when the power is turned on. It is. Further, the microprocessor 210 starts the image forming routine, sends a start signal to each load, and simultaneously sends a drive signal to the microprocessor 340. The RAM 220 is a non-volatile random access memory that retains recorded contents even when the power is turned off, and is a memory that records the history of the copying device, such as the number of copies,
Conditions such as variations in the bias voltage of each load and error occurrences are recorded. Particularly, in this embodiment, the occurrence of electric leakage in the AC line lOO and the occurrence of thermal runaway in the fixing device are stored. The driver 230 has a circuit output for driving a high voltage DC load 240, and the high voltage DC loads 240 include a charger, a separator, a transfer device, a developer, and the like. The driver 250 is a circuit that drives the AC load 140, and the AC load includes an exposure lamp, a main motor, and the like. Note that low-voltage DC loads include DC motors, solenoids, etc. that drive each part. The display unit 260 is a device provided in the operation unit and is a device for displaying error messages such as the occurrence of a jam.
In particular, in this embodiment, an earth leakage occurrence message and a fixing lamp thermal runaway message can be displayed. The operation of the copying apparatus of this embodiment will be explained below with reference to FIGS. 1 to 3. Fig. 2 is a chart 70 showing the operation of the copying machine of this embodiment, and Fig. 3 shows the output current from the detection circuit connected to the current difference detection means provided in the AC line of the copying machine of this embodiment. This is a time chart. In the time chart shown in FIG. 3, the current generated in the current difference detection means 310 and conducted through the detection circuit 320 is as follows:
Under normal conditions, when no ground fault or the like occurs, the current is approximately 2 to 3 μA. When the main switch is turned on at time t3 (Sl), AC current is conducted to the AC line 100 and the high voltage power supply unit 12
0, start up the low voltage power supply unit 130. At this time, relays 111 and 112 are in the on state in AC line 100, so AC load 140 is connected to AC line 100. As a result, AC power is supplied to the AC load 140. In the AC line 100, a current difference occurs between the forward and return currents at the above-mentioned time due to transient unbalance due to the capacitor charging current, etc. A current is generated in the Z CT 310 due to the current difference, and the detection circuit 32
At time t1, a current of about 150 mA is instantaneously conducted. However, the microprocessor 34
0, the earth leakage cutoff routine is not activated at time 1° as described above, and a signal of approximately 150 mA is not detected. Next, the operation of the process control circuit 200 after power is turned on will be described. The high voltage power supply unit 120 supplies power to the high voltage DC load 240 from time t1, and the low voltage power supply unit 1
30 is the microprocessor 210, RA from time t1.
Power is supplied to M 220, drivers 230 and 250, and display unit 260. As a result, the microprocessor 21
0 reads history information from RAM 220 (S2)
, the state of the earth leakage flag is detected (S3), and since the state of the earth leakage flag is off, the microprocessor 210.34
0 starts an initialize routine, and ends the routine at time t2 (S4). Here, t1~
For convenience, t2 is referred to as initialization time. O The microprocessor sensor 340 reads reference level data corresponding to 15 mA from the ROM corresponding to the reference level generation means at the initialization time, and initializes the normal reference level S rev. The standard level at this time is 1
It is 5mA. Microprocessor 210 t! At this time, a process control routine is activated (S5). On the other hand, microprocessor 3
40 starts the earth leakage cutoff routine at time t2. The microprocessor 210 activates the driver 25 at time t.
0 to drive the fuser lamp and simultaneously send control signals to microprocessor 340. The microprocessor 340 outputs 15 mA from the ROM according to the control signal.
The reference level data corresponding to S rev is read out and the reference level S rev is set in the control section. In the AC line 100, at time t3, a surge current caused by load fluctuation is conducted, albeit instantaneously. The detection circuit 320 instantaneously detects a current of approximately 30 mA due to the surge current, as shown in FIG. but,
Since the microprocessor 340 changes the reference level S rev to 40 mA as described above, the earth leakage cutoff routine does not malfunction and the circuit connecting the AC load 140 is not disconnected from the AC line 100 . When a predetermined period of time has elapsed since changing the reference level S rev, the microprocessor 340 reads the normal reference level data from the ROM and sets the normal reference level S
Reset rev. In other words, the normal reference level S r
ev is changed to 15mA. Similarly, the microprocessor 210 sequentially sends activation signals to the optical motor as a DC load, the main motor, exposure lamp, paper feed motor, etc. as an AC load at times t to 1a, and at the same time, the microprocessor 210
Send the same signal to 0. Thereby, the microprocessor 340 reads the reference level data from the ROM, changes the reference level, and resets it to the normal reference level of 5 reV after a predetermined period of time has elapsed. In this way, the image forming process is performed while preventing malfunctions without detecting instantaneous currents that are not caused by ground faults. If a ground fault occurs in the AC line 100, the microprocessor 340 connects the AC load 1 via the relay Ill, 112.
40 and stops the operation. At this time, the microprocessor 210 turns on the earth leakage flag in response to a signal from the microprocessor 340. The microprocessor 210 determines whether or not the set number of sheets has been reached (S6). Since the set number has not been reached, the process returns to step 2. The microprocessor 210 is the RAM 22
The history information is read from 0 (S2), the state of the earth leakage flag is detected (S3), and since it is in the on state, an earth leakage error message is displayed on the display unit 260 (S7), and the operation is stopped. In this way, the copying apparatus of this embodiment can stop operation due to the occurrence of an electric leakage and display the electric leakage error message 27 to notify the operator. Furthermore, the copying apparatus of this embodiment reads the history information before executing the initial operation, detects the occurrence of an electric leak from the information, and prevents restarting, thereby making it possible to prevent electric leakage accidents.

【Effect of the invention】

As explained above, the present invention includes a current difference detection means for detecting a current difference between AC lines that supply power from an AC power source to a load, a detection circuit connected to the current difference detection means, and a detection circuit connected to the current difference detection means. In a copying machine equipped with a control circuit that detects a current that continuously exceeds a reference level and turns off a relay installed in the AC line, a non-volatile memory that records the control history of the control circuit is provided to prevent electrical leakage. It is an object of the present invention to provide a copying apparatus having a function of preventing restart when an electric leakage occurs and notifying the user of the occurrence of an electric leakage.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of an AC line and a DC line in a copying machine equipped with an earth leakage interrupting circuit according to the present invention, and FIG. 2 is a block diagram showing an operation of the copying machine according to the present embodiment.
- Chart FIG. 3 is a time chart showing the output current from the detection circuit connected to the current difference detection circuit provided in the AC line of the copying apparatus of this embodiment. 100... AC line 101... AC power supply 1
11.112 ... ri -210.340・
...Microprocessor 220...RAM 310...Current difference detection circuit 320...Detection circuit

Claims (1)

[Claims] a current difference detection means for detecting a current difference between AC lines that supply power from an AC power source to a load; a detection circuit to which said current difference detection means is connected; and a current that continuously exceeds a reference level to said detection circuit. What is claimed is: 1. A copying apparatus comprising: a control circuit for detecting a current level and turning off a relay provided in the AC line, the copying apparatus comprising a nonvolatile memory for recording a control history of the control circuit.