JPH0564352A - Safety protection circuit - Google Patents

Abstract

(57) [Abstract] [Purpose] The purpose is to reduce the occurrence of arc noise during a momentary interruption of the main relay, and to prevent damage to the elements and RAM data. [Configuration] AC load 103 driven by an AC power source,
A fuse 101 for protecting 104, triacs 104 and 106, a main relay 109, and a main controller 1 for turning off the main relay 109 when a control abnormality occurs.
When the control abnormality occurs, the main controller 111 turns off the triacs 104 and 106 to cut off the power supply to the loads 103 and 104, and then turns off the main relay 109.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety protection circuit device used in a power supply circuit of a copying machine or the like.
The present invention relates to a safety protection circuit device designed to reduce the occurrence of arc noise.

[0002]

2. Description of the Related Art A conventional power supply circuit of a copying machine or the like incorporates a safety protection circuit device as a protection circuit against abnormal operation. This safety protection circuit device is composed of elements such as fuses, relays, and triacs for protecting each load driven by an AC power source in the event of an abnormality. In consideration of the safety of the equipment, such a safety protection circuit device is provided. Is essential.

A conventional safety protection circuit device for a copying machine is, for example, a protection circuit such as a fuse, a relay, a triac for protecting each load driven by an AC power source, and an AC.
A DC power supply unit provided between a main switch for turning on / off the power supply from the power supply and a main relay for turning off the power supply when an abnormality occurs, and a power supply from the DC power supply unit, which causes a control abnormality. It is composed of control means for turning off the main relay when it occurs.

As a concrete operation, for example, when an abnormality such as a jam occurs during the copy operation, the control means outputs a signal for turning off the main relay when the abnormality is detected,
Turn off the main relay. At this point, the power supply to the load driven by the AC power supply is cut off, which causes
Each AC load can be protected.

[0005]

However, according to the conventional safety protection circuit device, the power supply to each AC load is cut off by turning off the main relay when an abnormality occurs.
Although the AC load is protected, when an AC load with large power consumption or a plurality of AC loads are momentarily cut off by one relay, arc noise occurs, resulting in damage to the element or RAM of the control means. There is a problem that it may cause data corruption.

Particularly, in the copying machine, A during the copying operation is performed.
The C load (lamp heater, etc.) consumes a large amount of power, and a plurality of AC loads are driven at the same time, and the generated arc noise becomes large. ) RA
M Data may be destroyed. As the RAM data, data for maintaining the image quality adjusted for each copying machine and parameters necessary for the copying machine to operate normally are input, and when these data are destroyed. There is an inconvenience that a normal image cannot be obtained and the machine does not operate normally.

The present invention has been made in view of the above, and it is an object of the present invention to reduce the occurrence of arc noise at the time of a momentary interruption of a main relay and prevent damage to elements and RAM data.

[0008]

In order to achieve the above object, the present invention provides a fuse, a relay, an element such as a triac for protecting each load driven by an AC power source, and a main relay when a control abnormality occurs. In a safety protection circuit device including a control means for turning off, the control means provides a safety protection circuit device for turning off a main relay after turning off power supply to each load when a control abnormality occurs.

[0009]

In the safety protection circuit device of the present invention, the control means turns off the main relay after turning off the power supply to each load when a control abnormality occurs.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the safety protection circuit device of the present invention is applied to a copying machine will be described in detail below with reference to the drawings.

FIG. 1 shows the structure of the safety protection circuit device of this embodiment, in which a fuse 101 for preventing excess current is used.
And an AC load 10 driven by an AC power source at the time of abnormality
Main relay 10 for cutting off power supply to 3,105
2, the triacs 104 and 106 respectively connected to the AC loads 103 and 105, the interlock switches 107 and 108 that surely cut off the power supply to the circuit when the door of the copying machine is opened, and the copying machine. The main switch 109 for turning on / off the power source of the device, a DC power supply unit (so-called PSU) 110, and a main controller 111 for controlling the turning off of the main relay 102 and the triacs 104 and 106 when an abnormality occurs. The main controller 111 controls the entire copying machine, and receives an abnormality detection signal from an abnormality detection means such as a sensor (not shown).

With the above arrangement, the operation will be described with reference to the main flow of the copying machine of FIG. 2A and the flowchart of the abnormality detection subroutine of FIG.

When the main switch 109 is turned on, the main flow starts, and in S201, initial setting processing such as RAM clearing, I / O port setting, internal timer setting, and initial value setting is executed. Next, in the normal mode of S202, key input, drive of the main motor, drive of each stepping motor, input / output of each sensor provided in the conveyance path, and the like are executed as operations for copying. In other words, the normal mode is always set after the initial setting process is executed in S201.

During the normal mode, the abnormality detection subroutine performs interrupt processing at preset intervals. This program first checks whether or not there is an abnormality such as a jam (whether or not it is in the abnormal mode) (S203), and if there is no abnormality, the processing is terminated and returns to the normal mode. On the other hand, if there is an abnormality, it is checked whether or not power is being supplied to the load 1 (AC load 103) (S204). If power is being supplied, the liaac 1 (triac 10
4) is turned off to cut off the power supply (S205).

Next, it is checked whether or not power is being supplied to the load 2 (AC load 105) (S206), and if power is being supplied, the liaac 2 (triac 105) is turned off to supply power. Cut off (S207).

After that, the main relay 102 is turned off while all the loads are turned off (S208).

As described above, by turning off the main relay 102 after cutting off the power supply to each load, it is possible to reduce the occurrence of arc noise when the main relay is interrupted. Therefore, it is possible to prevent the element from being damaged or the RAM data from being damaged by the arc noise. Further, since the load on the main relay when the main relay is turned off is also reduced, the durability of the main relay can be improved.

[0018]

As described above, in the safety protection circuit device of the present invention, elements such as fuses, relays and triacs for protecting each load driven by an AC power supply, and the main relay are turned off when a control abnormality occurs. In the safety protection circuit device including the control means, the control means turns off the main relay after turning off the power supply to each load when a control abnormality occurs, so that arc noise is not generated when the main relay is interrupted. It is possible to reduce the size and prevent damage to the device and damage to the RAM data. Furthermore, as a secondary effect,
Since the load applied to the main relay when the main relay is turned off is also reduced, the durability of the main relay can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a safety protection circuit device of the present invention.

FIG. 2 is a flow chart for explaining the operation of the present invention.

[Explanation of symbols]

101 fuse 102
Main relay 103 105 AC load 104 106 Triac 107 108 Interlock switch 109 Main switch 110 DC power supply unit (PSU) 111 Main controller

Claims (1)

[Claims] 1. A safety protection circuit device comprising elements such as fuses, relays, and triacs for protecting each load driven by an AC power source, and control means for turning off a main relay when a control abnormality occurs The safety protection circuit device is characterized in that when the control abnormality occurs, the main relay is turned off after the power supply to each load is turned off.