JPH0415954B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a toner fixing device.

In recent years, flash discharge lamps have come to be used in toner fixing devices for facsimile machines and copying machines because they enable high-speed fixing and do not require waiting time. In such a fixing device, the toner is melted and fixed by the energy generated by the flash of the flash discharge lamp. Therefore, when toner is to be fixed, it is necessary to reliably generate a desired flash of light, that is, a flash of sufficient energy to fix the toner.

FIG. 1 shows an example of a conventional toner fixing device using a flash discharge lamp. 1 is a charging circuit connected to an AC power source, and a charging/discharging capacitor 2 is connected between the output terminals of this charging circuit 1. A flash discharge lamp 3 is connected to both ends of the charging/discharging capacitor 2. 31 is a trigger electrode arranged along the tube wall of the flash discharge lamp 3, and the trigger circuit 4 is connected to this trigger electrode 31. P is an input terminal for a trigger circuit drive signal for operating the trigger circuit 4, and this input terminal P is supplied with a signal that is synchronized with the conveyance of a support such as paper to the surface of which the toner to be fixed is attached to the fixing device. Then, a trigger circuit drive signal is input.

According to this toner fixing device, the charging/discharging capacitor 2 is charged by the charging circuit 1 to a predetermined voltage, ie, a predetermined voltage Vo at which the flash energy required for fixing the toner can be obtained. When a trigger circuit drive signal is input to the input terminal P in this state, the trigger circuit 4 is activated, thereby applying a high voltage to the trigger electrode 31, and the insulation between the discharge electrodes of the flash discharge lamp 3 is broken. The charge in the charging/discharging capacitor 2 is instantly released, producing a flash of light. This flash energy melts and fixes the toner on the support.

The toner is fixed in this way, but in the toner fixing device, if the flash discharge lamp 3 continues to be in a glow discharge state for some reason even after the previous flash, for example, this Even if the trigger circuit drive signal is input in this state, the voltage across the charging/discharging capacitor 2 has not reached the required predetermined voltage Vo, so a flash of sufficient energy will not be generated, and therefore the fixation on the support will not occur. The toner cannot be fixed. Alternatively, if the voltage across the charging/discharging capacitor 2 does not increase due to a failure of the charging circuit 1 and the trigger circuit drive signal is input in an insufficient state, the same result as described above will occur.

The present invention has been made based on the above circumstances, and it is possible to detect in advance if the voltage across the charging/discharging capacitor is insufficient and to know that the necessary fixation will not be achieved. The purpose of this device is to provide a toner fixing device that can fix toner, and its features include a flash discharge lamp for toner fixing that is equipped with a trigger electrode and emits light periodically at regular intervals, and a charger connected to both ends of the flash discharge lamp. Detects the discharge capacitor, the charging circuit that supplies charge to the charge and discharge capacitor in accordance with the light emission cycle, the trigger circuit that supplies trigger voltage to the trigger electrode of the flash discharge lamp, and the voltage across the charge and discharge capacitor. A voltage detection circuit is used to generate an alarm signal that operates when a certain amount of time has elapsed from the reference time corresponding to the start of charging of the charging/discharging capacitor, which is shorter than the time required to complete charging of the charging/discharging capacitor under normal conditions. a circuit, and an alarm signal generation circuit stop circuit that stops the operation of the alarm signal generation circuit when the detection voltage of the charging/discharging capacitor reaches a certain level that should be reached by the time the predetermined time elapses from the reference time. and a trigger circuit drive signal erasing circuit for erasing the trigger circuit drive signal when receiving an alarm signal from the alarm signal generating circuit.

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

FIG. 2 is an explanatory circuit diagram showing an embodiment of the present invention, in which 1 is a charging circuit, 2 is a charging/discharging capacitor, 3 is a flash discharge lamp, and 4 is a trigger circuit.
These configurations are the same as the device shown in FIG.

5 is a voltage detection circuit, and this voltage detection circuit 5 is constituted by voltage dividing resistors R9 and R10 connected in series to both ends of the charging/discharging capacitor 2. A voltage corresponding to the voltage across the charging/discharging capacitor 2 appears across the voltage dividing resistor R10.

6 is an alarm signal generation circuit stop circuit (hereinafter simply referred to as "stop circuit"), and this stop circuit 6 is composed of a first comparison circuit 61 and a reference voltage source 62. The first comparison circuit 61 includes a comparator IC3, a resistor R12 and a resistor R13 connected to one input terminal and the other input terminal of the comparator IC3, respectively, and a comparator IC3.
Zener diode connected to the output terminal of 3
ZD4, and the resistor R12 is connected to the connection point E between the resistor R9 and the resistor R10 of the voltage detection circuit 5. 62 is a reference voltage source for supplying the reference voltage V _REF1 to the other input terminal of the comparator IC3, and this reference voltage source 62 includes a resistor R11 and a variable resistor VR2 connected in series to a DC power supply DC, and a variable resistor VR2. It is composed of a Zener diode ZD3 connected to both ends of a variable resistor VR2,
The sliding contact F of the variable resistor VR2 is connected to the first comparator circuit 6.
1 resistor R13.

A resistor R14 and the base of a transistor Tr3 are connected in this order to the anode of the Zener diode ZD4, the collector of the transistor Tr3 is connected to the positive side of a DC power supply DC via a resistor R15, and the emitter of the transistor Tr3 is connected to the DC power supply.
Connected to the negative side of DC.

In the first comparison circuit 61, the connection point E
When the voltage V _E exceeds the reference voltage V _REF1 , a "high level" signal is output from the output terminal G, and this signal turns on the transistor Tr3. A signal that stops the operation of the alarm signal generation circuit 8, which will be described later (hereinafter simply referred to as a "stop signal").
) is output, and conversely, when it does not exceed the level, the output of the output terminal G becomes a "low level" and no stop signal is output from the connection point H.

8 is an alarm signal generation circuit, and this alarm signal generation circuit 8 includes an integration circuit 81 and a second comparison circuit 8.
2 and a reference voltage source 83.
The integrating circuit 81 includes a timer circuit IC1 and a DC power supply.
Resistor R2 and transistor Tr1 connected in series to DC, resistor R1 connected between the base and emitter of transistor Tr1, and DC power supply DC
resistor R3 and capacitor C1 connected in series with
It consists of a resistor R2 and a transistor Tr.
The connection point with the collector of 1 is connected to the input terminal a of the timer circuit IC1, and the connection point with the collector of 1 is connected to the input terminal a of the timer circuit IC1.
The connection point B with 1 is the output terminal b of the timer circuit IC1.
is connected to the reset terminal c of the timer circuit IC1.
is connected to the connection point H between the transistor Tr3 and the resistor R15, and the base of the transistor Tr1 is connected to the input terminal P at the connection point A.
When a signal is input to the input terminal a of the timer circuit IC1, an integral waveform of the input signal appears at the connection point B. At this time, if a "low level" signal, ie, a stop signal, is input from the connection point H to the reset terminal c of the timer circuit IC1, the voltage V _B at the connection point B becomes zero. As the timer circuit IC1, for example, "NE555" (manufactured by Signetics) can be used. The second comparison circuit 82 includes a comparator IC2 and resistors R5 and R6 connected to one input terminal and the other input terminal of the comparator IC2, respectively.
is connected to connection point B in the integrating circuit 81. An alarm signal generation terminal Q is connected to the output terminal D of the second comparison circuit 82. 83 is the reference voltage V _REF2 applied to the other input terminal of the comparator IC2.
This reference voltage source 83 includes a resistor R4 and a variable resistor VR1 connected in series to a DC power supply DC, and a variable resistor VR1.
Zener diode ZD1 connected to both ends of 1
and a sliding contact C of variable resistor VR1.
is connected to the resistor R6 of the second comparison circuit 82.

In the second comparison circuit 82, the connection point B
When the voltage V _B exceeds the reference voltage V _REF2 , an alarm signal is output. Conversely, when the voltage V B does not exceed the reference voltage V REF2, the output becomes zero and no alarm signal is generated.

11 is a trigger circuit drive signal disappearance circuit;
This trigger circuit drive signal disappearance circuit 11 includes a photocoupler PH, a resistor R8, and a transistor Tr.
2 and a Zener diode ZD2, the anode of the light emitting diode LED of the photocoupler PH is connected to the positive side of the DC power supply DC, the collector of the transistor Tr2 is connected to the cathode of the light emitting diode LED via a resistor R8, The emitter of transistor Tr2 is a Zener diode.
It is connected to the negative side of the DC power supply DC via ZD2. Photocoupler PH Photothyristor PHT
The anode of the photothyristor PHT is connected to the transmission path L of the trigger circuit drive signal, and the cathode of the photothyristor PHT is connected to the negative side of the DC power supply DC.

The magnitude of the reference voltage V _REF1 from the reference voltage source 62 is, for example, about 80% of the predetermined voltage Vo at which the voltage across the charging/discharging capacitor 2 can obtain the flash energy required for fixing the toner. It is set to a constant level that corresponds to the detected voltage when a certain value is reached, that is, the voltage V _E at the connection point E at that time. In this way, the magnitude of the reference voltage V _REF1 is set to approximately 80% of the predetermined voltage Vo of the charging/discharging capacitor 2.
%, a certain period of time shorter than the time required to complete charging under normal conditions will elapse from the reference time corresponding to the start of charging of the charging/discharging capacitor 2. The alarm signal generating circuit 8 can be activated when the detection voltage exceeds the predetermined level, and the charging/discharging capacitor 2 is reliably charged to the predetermined voltage Vo when the detected voltage exceeds the predetermined level. This is sufficient for detecting the state of charge. The magnitude of the reference voltage V _REF2 from the reference voltage source 83 is determined by setting the generation time of the trigger circuit drive signal as the reference time, for example, when flashing light is generated periodically at approximately 0.5 second intervals. For example, from the reference time
At about 60% of 0.5 seconds, that is, after about 0.3 seconds, it is set to a value equal to the magnitude of the voltage that would appear at connection point B under the condition that no stop signal is input. That is, in this example, the trigger circuit drive signal is input to the input terminal P.
When the trigger circuit drive signal is input to The time input to the terminal P is used as a reference time corresponding to the start of charging of the charging/discharging capacitor 2.

The alarm signal from the alarm signal generation terminal Q is supplied to, for example, a pilot lamp or a buzzer to generate an alarm, or is used as a signal to stop the operation of the toner fixing device.

According to the above embodiment, the charging/discharging capacitor 2
When the voltage across the voltage detector 5 reaches the predetermined voltage Vo, when a trigger circuit drive signal is input to the input terminal P at reference time _t0 as shown in FIG. Voltage V _E at connection point E
is larger than the reference voltage V _REF1 (V _F ), so the first
The output signal of the comparison circuit 61, that is, the voltage of the output terminal G
V _G is at a "high level", and this "high level" signal turns on the transistor Tr3, and a "low level" signal, that is, a stop signal, is sent from the connection point H to the reset terminal c of the timer circuit IC1 of the integrating circuit 81. Therefore, the output from the output terminal b is zero, and therefore the output of the second comparator circuit 82 is zero, so no alarm signal is generated, and the trigger circuit drive signal disappearing circuit 11 also does not operate. As a result, the trigger circuit drive signal is input to the trigger circuit 4, a flash of desired energy is generated, and the toner is fixed.

As the voltage across the charging/discharging capacitor 2 decreases due to the occurrence of this flash, the voltage V _E at the connection point E decreases and becomes smaller than the reference voltage V _REF1 (V _F ), and therefore the first comparison The output from the circuit 61, that is, the voltage V _G at the connection point G becomes "low level", and this signal turns off the transistor Tr3, and a "high level" signal is sent from the connection point H to the reset terminal c of the timer circuit IC1. The reset state of the timer circuit IC1 is released. On the other hand, a part of the trigger circuit drive signal inputted at the reference time t ₀ is inputted to the integrating circuit 81 from the connection point A, the transistor Tr1 is turned on, and the signal is inputted to the input terminal a of the timer circuit IC1.
The waveform of this input signal is converted into an integral waveform by the timer circuit IC1, the resistor R3, and the capacitor C1, and the signal of this integral waveform is output from the connection point B. Then, at time t ₁ immediately after the occurrence of the flash, the charging/discharging capacitor 2 starts to be charged again.
When the voltage V _E at the connection point E of the voltage detector 5 exceeds the reference voltage V REF1 (V F ) at time t ₂ before a certain period of time T has elapsed from time t ₀ , the voltage V E at the connection point E of the first comparison circuit 61 exceeds the reference voltage V _REF1 (V _F ). A “higher level” signal is generated, and this signal turns on transistor Tr3.
Reset terminal c of timer circuit IC1 from connection point H
A “low level” signal, that is, a stop signal is input to
The output at connection point B becomes zero. Therefore, the output from the output terminal D of the second comparison circuit 82 becomes zero, and as a result, no alarm signal is generated and the trigger circuit drive signal disappearance circuit 11 becomes inactive. Therefore, when the next trigger circuit drive signal is input to the input terminal P at the next reference time _t3 , this trigger circuit drive signal is input to the trigger circuit 4, a flash of the desired energy is generated, and the toner is Fixation takes place.

Due to the occurrence of this flash, the voltage V _E at the connection point E decreases, and the reset state of the timer circuit IC1 is released. On the other hand, a part of the trigger circuit drive signal inputted at reference time _t3 is inputted to the integrating circuit 81, and a signal having an integral waveform is outputted from the connection point B. The charging/discharging capacitor 2 starts charging again at time _t4 immediately after the flash occurs, but for example, due to a failure in the charging circuit 1, the voltage V _E at the connection point E of the voltage detector 5 remains constant after the trigger circuit drive signal is generated. If the reference voltage V _REF1 (V _F ) is not exceeded at time t ₅ after time T has elapsed, the voltage at the connection point G of the first comparator circuit 61
V _G remains at "low level" and no stop signal is generated from connection point H, so timer circuit IC1
is not in a reset state, and an integral waveform signal is continuously output from connection point B. At time _t5 when the integrated waveform signal exceeds the reference voltage V _REF2 (V _C ), a signal is output from the output terminal D of the second comparison circuit 82, and this signal generates an alarm signal from the alarm signal generation terminal Q. At the same time, in the trigger circuit drive signal disappearance circuit 11, the transistor Tr2
turns on and the photocoupler PH operates, thereby short-circuiting the transmission path L of the trigger circuit drive signal to ground, and the trigger circuit drive signal input to the input terminal P at the next reference time _t6 is connected to the trigger circuit. 4, the generation of the flash is stopped.

In this way, the detection voltage of the charging/discharging capacitor 2 should reach a certain level by the time T has elapsed from the reference time corresponding to the start of charging of the charging/discharging capacitor 2, that is, the time when the trigger circuit drive signal was input. If the level has been reached, an alarm signal is not generated and a flash of the desired energy is generated to fix the toner. If the detection voltage of the charging/discharging capacitor 2 has not reached a certain level, the alarm signal generation circuit 8 generates an alarm signal to detect that the required toner fixation is not achieved. can. In other words, since the point at which the certain period of time T has elapsed is earlier than the point at which fixing should start, it is possible to detect an abnormality with a large margin of time, and from this point on, it is possible to manage and manage the toner fixing device. Convenient for maintenance. For example, wasteful conveyance of the fixing paper can be stopped at an early stage, and adverse effects caused by abnormalities in the fixing system can be minimized. When an alarm signal is generated, the subsequent trigger circuit drive signal is eliminated by the trigger circuit drive signal elimination circuit 11, so it is possible to stop the generation of flash light in a state where there is insufficient energy, thereby wasting energy. can be prevented.

As described above, the present invention provides a trigger fixing flash discharge lamp that is equipped with a trigger electrode and emits light periodically at regular intervals, a charging/discharging capacitor connected to both ends of the flash discharge lamp, and a charging/discharging capacitor. A charging circuit that supplies a charging charge in accordance with the light emission cycle, a trigger circuit that supplies a trigger voltage to the trigger electrode of a flash discharge lamp, a voltage detection circuit that detects the voltage across the charging and discharging capacitor, and a an alarm signal generating circuit that operates when a certain period of time shorter than the time required to complete charging of the charging/discharging capacitor under normal conditions has elapsed from a reference time corresponding to the start of charging; and an alarm signal generating circuit that operates when the certain period of time has elapsed from the reference time. an alarm signal generation circuit stop circuit that stops the operation of the alarm signal generation circuit when the detection voltage of the charging/discharging capacitor reaches a certain level to be reached by the time the detection voltage of the charging/discharging capacitor reaches a certain level; Since this toner fixing device is characterized by comprising a trigger circuit drive signal disappearance circuit that causes the trigger circuit drive signal to disappear when the trigger circuit drive signal is being received, if the voltage across the charging/discharging capacitor is insufficient, By detecting this in advance, it is possible to know that the necessary fixation is not being achieved.

[Brief explanation of drawings]

FIG. 1 is an explanatory circuit diagram showing a conventional toner fixing device, FIG. 2 is an explanatory circuit diagram showing an embodiment of the present invention, and FIGS. FIG. 2 is an explanatory diagram showing voltage waveforms at points A to G for explaining. 1... Charging circuit, AC... Alternating current power supply, 2... Charging/discharging capacitor, 3... Flash discharge lamp, 4... Trigger circuit, 5... Voltage detection circuit, 6... Alarm signal generation circuit stop circuit, 61...first comparison circuit,
62...Reference voltage source, 8...Alarm signal generation circuit,
81...Integrator circuit, 82...Second comparison circuit, 8
3... Reference voltage source, 11... Trigger circuit drive signal disappearance circuit.

Claims (1)

[Claims] 1 A flash discharge lamp for toner fixing that is equipped with a trigger electrode and emits light periodically at regular intervals, a charging/discharging capacitor connected to both ends of this flash discharge lamp, and a charging/discharging capacitor that is charged with a charge according to the light emission cycle. a trigger circuit that supplies a trigger voltage to a trigger electrode of a flash discharge lamp;
A voltage detection circuit that detects the voltage across the charging/discharging capacitor, and a fixed period of time shorter than the time required to complete charging of the charging/discharging capacitor under normal conditions from the reference time corresponding to the start of charging of the charging/discharging capacitor. an alarm signal generation circuit that operates when the predetermined time has elapsed from the reference time; and an alarm signal generation circuit that operates when the detected voltage of the charging/discharging capacitor reaches a predetermined level by the time the predetermined time elapses from the reference time. A toner fixing device comprising: an alarm signal generation circuit stop circuit for stopping the alarm signal generation circuit; and a trigger circuit drive signal disappearance circuit for erasing the trigger circuit drive signal when receiving an alarm signal from the alarm signal generation circuit. Device.