JPS6117119B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lamp dimming device equipped with an abnormality detector for detecting lamp lighting abnormalities.

Copying machines and the like are generally equipped with light control devices without abnormality detectors, but some exposure lamps have adopted the following method to detect abnormal lighting.

(1) Method of directly detecting lamp load abnormalities (a) Install a temperature detector such as a temperature fuse or thermoswitch near the lamp load to detect the heat generated by the lamp load if it is lit for an abnormally long time. How to detect anomalies by detecting.

(b) A method in which a current transformer is installed in the power supply line of the lamp load, and abnormalities are detected by the length of time the current is generated.

(c) A method in which the light-emitting diode side of the photocoupler is connected to the power supply line of the lamp load, and an abnormality is detected based on the length of time that a detection current is generated from the phototransistor side.

(2) Method of indirectly detecting lamp load abnormalities A method of detecting abnormalities by measuring the drive time of the dimmer using a timer circuit, etc.

However, the method (1)-(a) above has disadvantages in the mounting position of the temperature fuse, etc. (temperature detection position) and its response, and is not practical.
- In method (b), a current transformer must be installed in addition to the feedback transformer installed in the lamp load for the dimmer, and there is a limit to the miniaturization of the area around the lamp load. In the method (), the photocoupler has a low breakdown voltage, so it is expensive because it requires resistors, diodes, etc. with relatively large capacitance. Also, especially
In the methods (1)-(b) and (1)-(c), a delay operation circuit or the like is also required at the subsequent stage, which poses further problems in achieving miniaturization and cost reduction. Furthermore, since the above method (2) does not actually check for failures in the lamp load, the reliability of direct detection is inferior.

Furthermore, since all of the above methods are external operations,
The internal processing of the lamp dimmer has not been done.

For this reason, it has been extremely difficult to match the conditions of the light control device and the external conditions.

This invention was made to solve the above-mentioned problems, and the lamp load drive voltage is controlled by the output of a feedback circuit that generates a DC voltage according to the drive voltage of the lamp load, so that the lamp load is always kept constant. In the lamp dimmer device, the lamp dimmer is configured to light up with a light emission output of the feedback circuit, and includes an output generation circuit that generates an output without affecting the output when the output of the feedback circuit is generated, and a predetermined generation time of the output of the output generation circuit. To provide a lamp dimming device equipped with an abnormality detector consisting of an abnormality detection circuit that operates when a time limit is exceeded, and a lamp load cutoff circuit or an abnormal state display circuit that operates according to the operation of the abnormality detection circuit, or both of these circuits. It is something.

Hereinafter, the content of the present invention will be explained with reference to the accompanying drawings, with reference to an embodiment applied to a copying machine.

FIG. 1 is a block diagram of a lamp dimming device equipped with an abnormality detector showing an embodiment of the present invention. In the figure, reference numeral 1 denotes a lamp load such as a halogen lamp, and the lamp is lit by being supplied with AC voltage (current) from an AC input circuit 2 via a lamp load drive circuit 3 such as a phase control circuit using a triac. 4 is a feedback circuit that detects the drive voltage of the lamp load 1, converts it into DC, and supplies it to the comparator circuit 5; 6 is a DC voltage (current) DC at a predetermined timing during copying;
is a DC input circuit to which lamp load 1 is input.
It is possible to set the output voltage supplied to the 7 is a soft start circuit provided to prevent rush current in the lamp load 1 during the initial operation of the lamp dimming device, to extend the life of the filament of the lamp load 1, and to downsize the lamp load drive circuit 3. , 8 is an AC-DC conversion circuit that rectifies and smooths the AC voltage (current) A and C supplied to the AC input circuit 2 and converts it into a DC voltage (current); 9 is a trigger circuit; A control signal S is supplied with a DC voltage from the soft start circuit 7, and the comparison circuit ₅ compares the signal _S2 from the DC input circuit 6 with the signal _S3 from the feedback circuit 4 and outputs the signal S1. _Four
A trigger pulse is generated by changing the phase with respect to the AC input according to to control.

In addition, in the trigger circuit 9, the control signal S ₄ (voltage) is changed into a resistance value change using, for example, a photocoupler, and the time constant of a time constant circuit that determines the timing at which the trigger pulse is generated is changed, so that the generated trigger pulse is changed. Controls the phase for AC input.

Reference numeral 10 indicates an output generation circuit that generates an output without substantially affecting the output of the feedback circuit 3, and 11 indicates a predetermined time period for generating the output of the output generation circuit 10 (a time corresponding to the exposure cycle). The abnormality detection circuit 12 is a lamp load cutoff circuit that operates when the abnormality detection circuit 11 detects an abnormality and operates when the abnormality detection circuit 11 detects an abnormality and operates. 1
3 is an abnormal state display circuit, and the abnormal state detection circuit 11
is provided to notify the operator when a lighting abnormality of the lamp load 1 is detected. 1
Reference numeral 4 denotes a DC level circuit, which converts the voltage converted into DC by the AC-DC conversion circuit 8 into a constant voltage level necessary for operating the abnormality detection circuit 11 and the abnormal state display circuit 13 and supplies the same. It is a circuit.

Next, the operation of the above-described embodiment configured in this manner will be explained. First, a switch (not shown) is turned on to input alternating currents A and C to the alternating current input circuit 2. Then, when the operator sets information such as the number of copies and turns on the copy start switch, the DC voltage D·C is input to the DC input circuit 6 at a predetermined timing. On the other hand, since the trigger circuit 9 is supplied with DC voltage from the AC-DC conversion circuit 8,
A trigger pulse starts to be generated by the signal _S1 from the soft start circuit 7. This trigger pulse controls the lamp load drive circuit 3, which controls the phase of the AC input from the AC input circuit 2 and supplies it to the lamp load 1. Then, the lamp load 1 is turned on and exposure is started. Then, the feedback circuit 4 detects the drive voltage of the lamp load 1, converts it to DC, and sends the signal S ₃ to the comparison circuit 5.
Output. Then, the comparator circuit 5 compares this signal S ₃ with the voltage signal S ₂ set by the DC input circuit 6 and outputs the control signal S ₄ , and the trigger circuit so that the lamp load 1 lights up with a predetermined light emission output. The phase of the trigger pulse generated at step 9 is changed.

Further, when the feedback circuit 4 outputs a signal, the output generation circuit 10 generates an output in response. and,
The abnormality detection circuit 11 measures the generation time of this output. For example, if the lamp load 1 does not turn off in a predetermined cycle for some reason, the abnormality detection circuit 11 is activated and the lamp load drive circuit 12 turns off the lamp load 1.
At the same time, the abnormal state display circuit 13 is operated to notify the operator of the lighting abnormality of the lamp load 1.

Next, a specific embodiment of the present invention will be described with reference to FIG. FIG. 2 shows only a portion related to the abnormality detector of the present invention as a specific circuit diagram. In the figure, _Q1 is a bidirectional three-terminal thyristor (hereinafter referred to as "TRIAT") constituting the lamp load drive circuit 3, and a trigger pulse from the trigger circuit 9 is applied to its gate G. A series circuit of a resistor R _{1 and} a capacitor C ₁ is normally connected between the electrodes T ₁ and T ₂ of the triax Q 1 in order to absorb the surge voltage generated by the lamp load 1 (inductive load). T is a feedback transformer,
The coil L ₁ on the primary side is connected in parallel to a series circuit of a lamp load cutoff circuit 12 and the lamp load 1, which will be described later, and the coil L ₂ on the secondary side is connected to a rectifier REC. Note that the AC impedance ωL ₁ of the primary coil L ₁ is made sufficiently larger than the AC impedance R ₁ +1/ωC ₁ of the resistor R ₁ and capacitor C ₁ described above. A series circuit of a current limiting resistor R ₂ and a smoothing capacitor C ₂ is connected in parallel to the rectifier REC, and a resistor R ₃ is connected in parallel to the capacitor C ₂ . A voltage is output from this connection point a to the comparator circuit 5 as a signal _S3 . A feedback circuit 4 is constituted by the feedback transformer T, the rectifier REC, the resistors R ₂ , R ₃ and the capacitor C ₂ .

In the output generation circuit 10, D ₁ is a reverse input prevention diode, and a rectifier in the feedback circuit 4.
Depending on the REC output voltage (voltage at point b), the resistance
It is connected to charge the capacitor _C3 via _R4 . Note that the charging time constants R ₄ and C ₃ are extremely small. Tr ₁ is an NPN type transistor, its base is connected to the point C where the charging voltage of the capacitor C ₃ appears via the resistor R ₅ , the emitter is connected to the common line 15, and the collector is connected to the resistors R ₆ and R ₇
It is connected to a constant voltage output point e of a DC level circuit 14, which will be described later. Tr ₂ is a PNP type transistor, and its base is connected to the voltage division point d formed by resistors R ₇ and R ₆ , its emitter is connected to the constant voltage output point e, and its collector is connected to the common line 15 via resistor R ₈ . be.

In the abnormality detection circuit 11, a series circuit of a charging capacitor _C4 and a resistor _R9 is connected between a point f, which is an output terminal of the output generation circuit 10, and a common line 15. The charging time constants C ₄ and R ₉ are set to be slightly longer than the time corresponding to the exposure cycle of the copying machine so that the Zener diode ZD ₁ (described later) does not reach the Zener voltage during the exposure cycle. resistance
R ₉ is connected in parallel with the anode of diode D ₂ on the common line 15 side, and when lamp load 1 lights up normally and the exposure cycle ends and transistor Tr ₂ is turned off, capacitor C ₄ → resistor The charge in capacitor C ₄ is discharged in a short period of time in the loop of R ₈ → diode D ₂ . ZD ₁ is a Zener diode, whose anode is connected to the connection point g of capacitor C ₄ and resistor R ₉ , and its cathode is connected to resistor R ₁₀
is connected to point f through a parallel circuit with capacitor C5 and capacitor _C5 . The Zener voltage (breakdown voltage) of this Zener diode ZD ₁ is selected to be less than the voltage generated across resistor R ₈ . capacitor
_C5 is a capacitor for noise prevention. Q ₂ is a programmable union transistor (hereinafter abbreviated as "PUT"), whose gate G
is connected to the h point on the cathode side of the Zener diode ZD ₁ , the anode A is connected to the f point, and the cathode K is connected to the common line 15 via the relay coil Ry.
Furthermore, a diode _D3 for absorbing reverse voltage is connected in parallel to the relay coil Ry.

Then, the normally closed contact Ra ₁ of the relay coil Ry constituting the lamp load cutoff circuit 12 is inserted between the triax Q ₁ and the lamp load 1 as described above, and the normally closed contact Ra ₂ of the relay coil Ry is used to indicate an abnormal state. circuit 1
It is inserted between the point f and the series circuit of the light emitting diode LD and its protective resistor _R11 constituting No. 3. In addition, the output terminal of the AC-DC conversion circuit 8 and the common line 1
5, there is a resistor that constitutes the DC level circuit 14.
R ₁₂ and the Zener diode ZD ₂ are connected in series, and a constant voltage corresponding to the Zener voltage of the Zener diode ZD ₂ is output from point e.

Next, to explain the operation of this circuit, when a power switch and a copy start switch (not shown) are turned on and the copying machine enters an exposure cycle, a trigger pulse from the trigger circuit 9 triggers the try-out _Q1.
turns on at a predetermined phase angle. Thereby, the AC input supplied from the AC input circuit 2 is phase-controlled by the triax _Q1 , flows to the lamp load ₁ via the normally closed contact Ra1, and lights the lamp load 1. When the lamp load 1 is lit, a voltage is generated across it, so a voltage is also applied to the coil L ₁ on the primary side of the feedback transformer T, and a voltage is generated in the coil L ₂ on the secondary side. This AC voltage is rectified by the rectifier REC, further divided by the resistors R ₂ and R ₃ , smoothed by the capacitor C ₂ and output to the comparator circuit 5, and the lamp load 1 is lit with a constant light output according to the procedure described above. The signal is processed to

Note that if the resistance of the lamp load 1 is R ₀ , R ₀ is very small and R ₀ ≪ωL ₁ holds, so the combined impedance is approximately R ₀ , while R ₀ < R ₁ +
1/ωC ₁ holds, so when the triac Q ₁ is turned off, it is bypassed with the resistor R ₁ and the capacitor C ₁ , and the lamp load 1 is not turned on, and no feedback voltage is generated on the secondary side of the feedback transformer T. .

Now, while lamp load 1 is lit, output generation circuit 1
0 capacitor C ₃ has a diode D ₂ and a resistor R ₄
Since the DC voltage rectified by the rectifier REC continues to be charged through the transistor REC, the potential at point C rises, and the transistor _Tr1 remains on. Transistor Tr ₁
When turned on, the DC current supplied from the AC-DC conversion circuit 8 whose voltage is regulated by the Zener diode ZD ₂ flows through the resistors R ₇ and R ₆ to the emitter of the transistor Tr ₁ , so the potential at point d decreases. , transistor Tr ₂ is also turned on. these two transistors
Tr ₁ and Tr ₂ remain on as long as there is feedback output.
When transistor Tr ₂ turns on, abnormality detection circuit 1
1 capacitor C ₄ begins to be charged with charging time constant R ₉ and C ₄ . At the moment when the transistor Tr ₂ is turned on, the potential on the anode side of the Zener diode ZD ₁ is equal to the potential on the cathode side, but when the capacitor C ₄ starts to be charged, the potential on the anode side starts to decrease.

However, as mentioned above, the charging time constant
Make R ₉ and C ₄ longer than the exposure cycle of the copier, and use the Zener diode during the exposure cycle.
Since ZD ₁ is prevented from reaching the Zener voltage, if the lamp load 1 is normally turned on and off for a predetermined period of time, the transistors Tr ₁ and Tr ₂ are turned off before the Zener diode ZD ₁ breaks down. Therefore, the charge stored in the capacitor _C4 is discharged in a short time through the loop of the resistor _R8 and the diode _D2 .

However, if for some reason the lamp load 1 remains lit even after completing the exposure cycle, the capacitor C ₄ will be charged to the Zener voltage of the Zener diode ZD ₁ and the Zener diode ZD ₁ will break down. As a result, a breakdown current flows through the resistor _R10 and a voltage drop occurs. Therefore, the potential at point h decreases, and the potential at the gate G of PUTQ ₂ becomes lower than the potential at the anode A, so
PUTQ ₂ turns off and current flows through relay coil Ry. When current flows through relay coil Ry,
Immediately close its normally closed contact Ra ₁ (lamp load cutoff circuit 1
2) opens to cut off the power supply to the lamp load 1 and turn off the lamp load 1, and its normally open contact Ra ₂ closes to close the light emitting diode of the abnormal status display circuit 13.
Power is supplied to the LD to cause it to emit light and notify the operator of an abnormality in lamp load 1.

Note that after the Zener voltage applied to the Zener diode ZD ₁ breaks down, the gate potential of PUTQ ₂ becomes constant due to the voltage drop across the resistors R ₉ and R ₁₀ . Furthermore, even if the normally closed contact Ra ₁ is opened and the lamp load 1 is turned off, R ₁ +1/ωC ₁ <<ωL ₁ holds, so the feedback transformer T is connected via the resistor R ₁ and the capacitor C ₁ . Current flows through the primary coil _L1 ,
Voltage continues to be generated on the secondary side. Therefore, transistors Tr ₁ and Tr ₂ are maintained in the on state,
The power supply to PUTQ ₂ is not cut off, current continues to flow through the relay coil Ry, and the normally closed contact Ra ₁ remains open and the normally open contact Ra ₂ remains closed.

All power to this abnormality detector is cut off by turning off the power switch (not shown).
When PUTQ ₂ turns off, the charge in capacitor C ₄ is also discharged and is automatically reset.

By the way, if the circuit is configured as shown in FIG. 2, a disconnection of the lamp load 1 can also be detected.

In other words, if the lamp load 1 is disconnected, for example, during the exposure cycle, R ₁ + 1/ωC ₁ ≪ωL ₁ holds true in the same way as when the normally closed contact Ra ₁ opens, so the resistance
A current flows through the primary coil of the feedback transformer T via R ₁ and the capacitor C ₁ , and voltage continues to be generated on the secondary side. Therefore, as in the previous case,
PUTQ ₂ is turned on, relay coil Ry is energized, normally open contact Ra ₂ of abnormal status display circuit 13 is closed, and light emitting diode LD emits light to notify an abnormality (in this case, a disconnection to the lamp load). . Of course, it goes without saying that even if the lamp load 1 is disconnected before the exposure cycle, it can be detected in the same way.

As described above, according to the present invention, an abnormality in the lamp load is detected using the output of the feedback circuit of the conventional dimmer, so it is easy to downsize the lamp load area. Not only that, but since there is no need to provide expensive parts, it is possible to easily reduce costs. Furthermore, there is no need to match the light control device with the light control device, and since it is essentially the same as directly detecting the lamp load, the reliability of detection is high. Furthermore, it is also possible to detect a disconnection in the lamp load, and is automatically reset when the power is turned off, increasing its value as an abnormality detector.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a lamp dimming device equipped with an abnormality detector showing an embodiment of the invention, and FIG. 2 is a circuit diagram of a portion related to the abnormality detector showing a specific embodiment of the invention. 1... Lamp load, 2... AC input circuit, 3...
...Lamp load drive circuit, 4...Feedback circuit, 10...
...Output generation circuit, 11...Abnormality detection circuit, 12...
... Lamp load cutoff circuit, 13 ... Abnormal condition display circuit, Q ₁ ... Bidirectional 3-terminal thyristor (triack), T ... Feedback transformer, ZD ₁ , ZD ₂ ...
Zener diode, Q ₂ ... Programmable union transistor (PUT), Ry ...
Relay coil, Ra ₁ ...normally closed contact, Ra ₂ ...normally open contact, LD...light emitting diode.

Claims (1)

[Claims] 1. In a lamp dimmer device in which a lamp load drive circuit is controlled by the output of a feedback circuit that generates a DC voltage according to a drive voltage of a lamp load, the lamp load is always lit with a constant light emitting output. An output generation circuit that generates an output without affecting the output when the circuit generates an output, an abnormality detection circuit that operates when the output generation time of the output generation circuit exceeds a predetermined time, and an abnormality detection circuit that operates when the output generation time of the output generation circuit exceeds a predetermined time. 1. A lamp dimming device equipped with an abnormality detector, characterized in that the abnormality detector is provided with an abnormality detector consisting of a lamp load cutoff circuit, an abnormal state display circuit, or both of these circuits, which are activated when activated.