JPS5842982Y2 - Rokourampu Ijiyou Renzoku Tenshutsusouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exposure lamp abnormal continuous lighting detection device for detecting abnormal continuous lighting of an exposure lamp in an electronic electrostatic copying machine.

If an electronic electrostatic copying machine uses a halogen lamp with a high wattage as the exposure lamp, various problems may occur due to temperature rise due to abnormal continuous lighting of the exposure lamp. A device is provided to detect this and stop the entire operation.

Conventionally, as shown in FIG. 1, this device closes a switch SW during exposure to energize a relay RA, and its normally open contact RA1-a forms a gate circuit of the triac TRI, and the exposure lamp L In an exposure lamp drive circuit that energizes the exposure lamp L through a triac TRI,
The voltage between both ends of the relay RA3 is detected and its normally open contact RA
In 3-8, relay RK is activated when exposure lamp L is abnormally lit continuously.
There are two methods: energizing the relay RK and stopping the electronic electrostatic copying machine using the contacts of this relay RK; and, as shown in FIG. There is a method in which a normally open contact RA3-a is used to energize a relay RK when the exposure lamp L is abnormally lit continuously, and the contact stops the electronic electrostatic copying machine.

In addition, in FIG. 1 and FIG. 2, R1 and R2 are resistances,
C1 is a capacitor, D1. D2 is a diode.

Further, RA2 is a timer relay, and has a structure such that contacts RA2-8 close when the input terminal thereof is energized for a predetermined period of time or more.

Furthermore, RA3 is also a timer relay, and has a structure in which a contact RA3-a closes when the input terminal is energized for a predetermined period of time or more.

However, in such a device, the exposure lamp L
relay RA2. to detect abnormal continuous lighting. R.A.
3, mechanical parts are used, resulting in low reliability and high cost.

In view of these points, the present invention aims to provide a highly reliable and inexpensive exposure lamp abnormal continuous lighting detection device that does not use mechanical parts.

An embodiment of the present invention will be described below with reference to the drawings.

As shown in Fig. 3, an exposure lamp L consisting of a halogen lamp in an electronic electrostatic copying machine is connected to the primary winding of a current detection transformer T2 between terminals B, , B, connected to a 100V AC power supply. and triac TRI are connected in series, and a resistor R is connected between the gate of triac TRI and terminal B1 via normally open contact RA1-a of relay RA1.
1 is connected.

Further, a series circuit of a resistor R2 for absorbing abnormal voltage and a capacitor C1 is connected in parallel with the triac TRI, and one end of the secondary winding of the transformer T2 is connected to the anode of the diode D3 and one end of the resistor R3 for absorbing abnormal voltage. .

The other end of the secondary winding of the transformer T2 is connected to the other end of the resistor R3, and also to one end of each of the smoothing capacitor C2 and the bias resistor R5, and the base of the output PNP transistor TR1 via the resistor R4. Ru.

The resistor R4 is for lowering the voltage across the capacitor C2.

The cathode of diode D3 is connected to the other end of capacitor C2, and is also connected to the other end of resistor R5 and the emitter of transistor TR1 via bias resistor R6.

The emitter of the transistor TR1 is the positive terminal P of the DC power supply.
The collector is connected to the negative terminal N of the DC power source via a detection circuit A for detecting abnormal continuous lighting of the exposure lamp.

This detection circuit A is constructed using a timer as described later.

Further, a switch SW, which is closed during exposure, and a parallel circuit of a relay RA1 and a diode D2 are connected in series between the terminals P and N.

Now, when the switch SW is closed, the relay RA1 is energized and operates, its normally open contact RA1-a is closed, and an input is given to the gate of the triac TRI.

Therefore, the triac TRI conducts and the exposure lamp L
energized through the primary winding of the transformer T.

In this case, the voltage drop on the primary side of the transformer T2 is set to a level that does not adversely affect the amount of light from the exposure lamp L.

When current flows through the primary side of the transformer T2, a voltage is induced on the secondary side in proportion to the current.

The output of the secondary side of the transformer T2 is half-wave rectified by the diode D3, smoothed by the capacitor D2, and becomes a DC voltage, which is applied as a forward bias voltage to the base of the transistor TR1 by the resistors Rs and Re.
R1 becomes energized and an input signal is applied to detection circuit A.

Under normal conditions, the exposure lamp L is lit for a certain period of time for each copying operation.

However, when the exposure lamps L and 'l (in an abnormal continuous lighting state), the detection circuit A receives an input signal continuously for a certain period of time or more, generates an output signal, and this output signal activates the stop circuit, causing the electronic Stop the electrostatic copying machine.

Here, the resistor R3 is for absorbing high voltage when it occurs on the secondary side of the transformer T2, but the resistor R3 is for absorbing high voltage generated on the secondary side of the transformer T2. If a trigger signal is applied to the gate of the triac TRI while a maximum voltage of 141 V of AC 100 V is applied across B2, the transformer T2 will change the magnetic flux dφ.
Since /dt becomes a large value, a considerably high voltage is induced on the secondary side.

Since the output of the secondary side of this transformer T2 does not have much power, the power is lost by the resistor R3 and the high voltage is absorbed.

To give an example using actual numerical values, the output voltage on the secondary side of the transformer T2 became more than 1.2 mm without the resistor R3, but it became about 100 mm by inserting the resistor R3.

As the above-described detection circuit A and stop circuit, for example, a circuit as shown in FIG. 4 is used.

That is, a resistor R7 and a capacitor C3 are connected in series between the collector of the transistor TR and the terminal N.
A connection point between the resistor R7 and the capacitor C3 is connected to the anode of the diode D4 and the base of the NPN transistor TR2.

A resistor R8 is connected between the cathode of the diode D4 and the terminal N, and a time constant circuit is constituted by the resistors R7 and R8, the capacitor C3, and the diode D4.

The emitter of the transistor TR2 is commonly connected to the emitter of the NPN transistor TR3 through a resistor R9, and the collector is connected to a terminal P through a resistor RIO.

The base of the transistor TR3 is connected to the connection point of the resistors R11 and R12, and the resistors R1□ and R12 are connected to the resistor RIO.
It is connected in series between terminals P and N via.

The collector of transistor TR3 is connected to terminal P via resistor R13, transistors TR2, TR3 and resistors R9 to R13 constitute a Schmitt trigger circuit, and this Schmitt trigger circuit and the above-mentioned time constant circuit constitute a timer. .

The base of a PNP transistor TR4 is connected to the collector of the transistor TR3 via a resistor R14, and the emitter of this transistor TR4 is connected to a terminal P.

The collector of the transistor TR4 is connected to the terminal N via a resistor R15, and also to the base of a PNP transistor TR5, and the emitter of this transistor TR5 is connected to the terminal P.

The collector of transistor TR5 is connected to terminal N via relay RK, and the contacts of this relay RK are wired to stop the electronic electrostatic copying machine during operation.

Therefore, when the transistor TR1 is on, the capacitor C3 is charged from the collector output through the resistor R7, and when the transistor TR1 is off, the capacitor C3 is charged by the diode D4 and the resistor R.
8 and a loop that discharges from resistor R7 through resistor R8.

The charging voltage of this capacitor C3 is the transistor TR2,
It is added to a Schmitt trigger circuit using TR3, and when the voltage exceeds a certain level, this Schmitt trigger circuit operates.

That is, when the exposure lamp L is in an abnormal continuous lighting state and the collector output of the transistor TR is output for a certain period of time or more, the transistor TR2 in the Schmitt trigger circuit is inverted to the on state by the charging voltage of the capacitor C3, and the transistor TR3 is turned off.

Therefore, the transistor TR4 is turned off, the transistor TR5 is turned on, and the relay RK is operated, and its contacts stop all operations of the electronic electrostatic copying machine.

Note that in FIGS. 1 to 4, RK is a keep relay, and once activated, it continues to maintain its activated state unless a release command is given.

Therefore, as shown in Figure 5, the normally open contact R of the keep relay RK
If K-b is placed in the partial SCC that controls the sequence of the copying machine, once the keep relay RK is activated, it will not be possible to make another copy.

Also, as shown in Figure 6, the normally open contact RK- of the keep relay RK
a is the light emitting diode LED in the display part of the panel
If the resistor R16 is connected in series between the machine (or the miniature bulb) and the power source, it is possible to indicate with a light emitting diode LED that the machine is not working because the keep relay RK has worked.

Since the keep relay RK can be released by applying a magnetic field of opposite polarity to that when it is activated, it normally has an activation coil and a release coil, and is deactivated by energizing the release coil.

As described above, according to the exposure lamp abnormal continuous lighting detection device according to the present invention, the current flowing through the exposure lamp is detected by a transformer, the output signal is converted into a DC signal by a rectifier circuit, and this DC signal is continuously turned on for a certain period of time or more. Since the output is detected by a timer, there is no need to use mechanical parts such as relays, which improves reliability and reduces costs.

Furthermore, since the current flowing through the exposure lamp is detected, abnormal continuous lighting of the exposure lamp can be detected even when the exposure lamp is not being exposed, and deterioration of the photoreceptor drum can be prevented.

[Brief explanation of drawings]

Figures 1 and 2 are circuit diagrams for explaining a conventional device, Figure 3 is a circuit diagram showing an embodiment of the present invention, and Figure 4 is a circuit diagram showing a part of the same embodiment in detail. , FIG. 5, and FIG. 6 are circuit diagrams showing an example of the use of the present invention. L...Exposure lamp, T...Transformer,
D3... Rectifier diode, C2...
Smoothing capacitor, A...Detection circuit.

Claims (1)

[Scope of utility model registration request] In a copying machine, there is a transformer that detects the current flowing through the exposure lamp, a rectifier circuit that converts the output signal of this transformer into a DC signal, a transistor that operates based on the output signal of this rectifier circuit, and a transistor that operates when the exposure lamp is turned on. A device for detecting abnormal continuous lighting of an exposure lamp, comprising a timer that is driven and generates an output signal when the exposure lamp is abnormally lit continuously for a certain period of time or more.