JP2978376B2 - Lighting control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to lighting control such as copy lamp voltage control of a copying machine.

[0002]

2. Description of the Related Art Known materials include Japanese Patent Application Laid-Open No. 2-1767.
72. FIG. 8 shows a configuration diagram thereof. Similarly, FIG. 9 shows a time chart thereof.

The device shown in FIG. 8 has terminals T1 and T2 to which an AC power supply 81 such as a commercial power supply is applied, and an output adjusting element 83 such as a bidirectional thyristor connected to the terminal T1.
A control circuit 85; a detection circuit 86 for detecting an output voltage of the output adjusting element 83;
And a lamp load 84 such as a halogen lamp connected between the output terminals T3 and T4.

If the on / off control signal indicates, for example, a low level, that is, on, a phase control signal, for example, is input from the control circuit 85 to the output adjusting element 83, and the AC power supply 81
Is controlled and output. The output voltage of the output adjustment element 83 is detected by the detection circuit 86, and the control circuit 85 adjusts the phase control signal applied to the output adjustment element 83 based on the detection result. Thereby, an AC power supply having a desired conduction angle is output from the output adjustment element 83,
A lamp load 84 via a normally closed switch 82
Is supplied with power. As a result, the lamp load 84 is lit at a desired, for example, constant brightness.

On the other hand, if the on / off control signal indicates the off state, the control circuit 85 outputs the output adjusting element 83
, A predetermined control signal is input or not input, whereby the output adjusting element 83 is cut off. Thus, the lamp load 84 blinks according to the state value of the on / off control signal.

In such an operation, the control circuit 85
Compares the state value of the on / off control signal 91 with the lighting state 92 of the lamp load 84, for example, as shown in FIG. That is, for example, if the lamp load 84 is lit when the on / off control signal indicates the on state, it is determined that the lamp load 84 is normal, and when the on / off control signal indicates the off state, the lamp load 84 is turned off. If it is done, it will be normal. However, if the lamp load 84 is turned on even though the control signal is in the off state, it is determined that the circuit is abnormal, and the operation of the control circuit 85 switches the switch 82 to the off state, and the power supply to the lamp load 84 Is shut off. Thus, even when a short circuit of the output adjustment element 3 or other circuit abnormality occurs, the power supply to the lamp load 84 is accurately cut off. In order to detect the lighting state of the lamp load 84, for example, it is possible to perform pseudo detection based on the presence or absence of the output of the detection circuit 86 in FIG. It is also possible to detect by a detecting element.

[0007]

In the conventional device, the ON / OFF
Since protection is provided by the OFF control signal and detection of lamp lighting, the lamp may also be lit when a signal is generated due to malfunction of the control signal generator, etc. is there. The circuit is complicated,
This will increase costs.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a lighting control device according to a first aspect of the present invention controls a voltage applied to a copy lamp to a copy lamp by a central processing circuit. In a lighting control device for a copying machine, a voltage applied to a copy lamp when the copy lamp is turned on.
Means, and the detected voltage applied to the copy lamp is
If the voltage is higher than the rated voltage of the copy lamp,
A lighting control device comprising a lighting prohibition circuit for prohibiting lighting of the lighting device.

The lighting control device according to the second aspect is the first aspect.
The lighting control device according to claim 1, further comprising: means for detecting a change in the input power supply; and means for switching a reference voltage of the lighting inhibition circuit to at least two stages based on the detection result. It is.

[0010] The lighting control device according to the third aspect is the first aspect.
In the lighting control device described above, a means for generating a full-wave rectified signal proportional to the input power, a means for integrating the full-wave rectified signal, and a lamp lighting inhibition area proportional to the input power fluctuation by the two signals. A lighting control device.

According to a fourth aspect of the present invention, there is provided a lighting control device.
In the lighting control device described above, a means for generating a full-wave rectified signal proportional to the input power, a means for comparing the signal with a reference voltage, and, based on the signal output, a fixed time zone from a zero cross point of the input power waveform. And a means for invalidating only the lamp lighting signal.

[0012]

According to the above arrangement, the voltage applied to the copy lamp is set to a medium level.
In the lighting control apparatus as Gosuru control by central processing circuit, co
Make sure that no voltage exceeding the rated voltage is applied to the peak lamp.
This prevents the lamp from being burned out due to overvoltage.
Can, retaining clips holding the life of copy lamps that are guaranteed by the standards
Can be .

In particular, according to the lighting control device according to the second and third aspects, the protection voltage can be switched in accordance with the fluctuation amount of the power supply voltage, so that the protection voltage can be held at an appropriate value by the fluctuation of the power supply voltage.

Further, according to the lighting control device of the fourth aspect, a circuit configuration that does not use an integrator for setting the prohibited area enables quick response and reliable protection.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention; The present invention is, of course, not limited to these embodiments.

FIG. 1 is a block diagram of the device of the present invention, wherein 1 is a triac, 2 is a power transformer , 3 is a lamp load, 4 is an AC power supply, and 5 is a control circuit. FIG. 2 is a circuit diagram of an embodiment of the present invention, and 21 is a comparator. FIG. 3 is a time chart of the circuit shown in FIG. 2, where 31 is a FW (full-wave rectified waveform), 32 is a CPU signal, and 33 is a copy ramp signal. More specifically, in the copying machine, as shown in FIG. 1, in the copy lamp control, the brightness is adjusted by turning on the triac 1 to turn on the lamp 2 and changing the on-duty by the rising signal from the CPU. Normally, a rise signal is generated by software based on a time difference from the zero-cross timing of the power supply, and control is performed. Here, when a rising signal is generated in a region where a voltage higher than the rating of the lamp is applied due to a malfunction of the CPU or the like, a circuit shown in FIG. 2 is provided in the control circuit 5 in order to prevent an overvoltage or damage to the lamp. In the comparator 21 in the figure, a reference voltage is set such that an overvoltage is not applied to the lamp, and the output of the power transformer is subjected to full-wave rectification (F
W) to the positive terminal. As shown in the time chart of FIG.
1 is in a low level state. By connecting this to the control circuit 5 and keeping the connection point at a low level even when a signal is output from the CPU in the prohibited area, no signal is transmitted to the next triac and the lamp is not turned on. By suppressing the lighting signal as described above, abnormal lighting due to overvoltage of the lamp is prevented.

As a feature of the circuit shown in FIG. 2, a lamp trigger prohibition time zone can be created by a very simple circuit, and even when CPU control is abnormal, application of overpower to the lamp can be prohibited.

FIG. 4 is a circuit diagram of another embodiment of the present invention, and 41 is a comparator. FIG. 5 shows a full-wave rectified waveform (FW) in the circuit of FIG. More specifically, the CPU reads the fluctuation of the power supply voltage and switches the transistor so that the reference voltage of the comparator 41 becomes an appropriate value for the fluctuation of the power supply. With this, even if the power supply voltage fluctuates, the maximum applied voltage of the lamp is kept constant regardless of the power supply fluctuation by determining the prohibited area for the voltage,
Prevent abnormal lighting due to overvoltage. As the number of transistors to be switched is increased, the reference value can be corrected for minute power supply fluctuations. FIG. 5 shows a correction state of the prohibited area with respect to the power supply fluctuation.

As a characteristic of the circuit shown in FIG. 4, the input voltage fluctuation can be accurately read by an analog conversion port of the CPU by integrating the FW (full wave rectification) signal shown in FIG. Since the lamp prohibition time zone can be set in multiple stages based on this data, the lamp upper limit power with high accuracy can be set. With the addition of this circuit, even if an abnormality occurs between the output port of the CPU and the transistor A, abnormal lighting can be prevented.

FIG. 6 is a circuit diagram of another embodiment of the present invention, and 61 is a comparator. FIG. 7 is a time chart for the circuit of FIG. 6, where 71 is a copy ramp signal, and 72 is FW
(Full-wave rectified waveform) 73 is a CPU signal. More specifically, the reference voltage of the comparator 61 is obtained by amplifying the integral of the FW waveform so as to be at an appropriate level with respect to the power supply fluctuation. FW following power supply voltage fluctuation
, The reference voltage also changes. Therefore, since the maximum applied voltage can be kept constant with respect to the power supply fluctuation, abnormal lighting due to overvoltage can be prevented. Since the reference value is obtained from the full-wave rectification level, the reference value can be corrected substantially linearly with respect to power supply fluctuation. FIG. 7 shows the state of the maximum voltage waveform that can be applied to the lamp with respect to the power supply voltage.

As a feature of the circuit shown in FIG. 6, since the reference voltage can be automatically changed in accordance with the fluctuation of the input voltage in this circuit, even if the input voltage fluctuates and the CPU is abnormally controlled. Overpower application to the lamp can be prohibited.

The present invention is not limited to the embodiment described above and shown in the drawings, but it is needless to say that the present invention can be appropriately modified and implemented without departing from the scope of the invention.

[0023]

According to the present invention, the copy lamp voltage applied to Te braking Gosuru such lighting controller odor <br/> the central processing circuit, so that the voltage exceeding the rated to the copy lamp is not applied
By the, preventing lamp breakage caused by over-voltage
It is possible, the life of the copy lamp is guaranteed can <br/> one coercive in standards.

In particular, according to the lighting control device according to the second and third aspects, the protection voltage can be switched in accordance with the fluctuation amount of the power supply voltage, so that the protection voltage can be maintained at an appropriate value by the fluctuation of the power supply voltage.

Further, according to the lighting control device of the fourth aspect, a circuit configuration that does not use an integrator for setting the prohibited area enables quick protection and reliable protection.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of the device of the present invention.

FIG. 2 is a circuit diagram of an embodiment of the present invention.

FIG. 3 is a time chart of the embodiment of the present invention.

FIG. 4 is a circuit diagram of an embodiment of the present invention.

FIG. 5 is an explanatory diagram of an embodiment of the present invention.

FIG. 6 is a circuit diagram of an embodiment of the present invention.

FIG. 7 is an explanatory diagram of an embodiment of the present invention.

FIG. 8 is a configuration diagram of a conventional device.

FIG. 9 is a time chart of the conventional device.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 Triac 2 Power transformer 3 Lamp load 4 AC power supply 5 Control circuit 21 Comparator 31 Full-wave rectified waveform 32 CPU (central processing unit) signal 33 Copy lamp signal 41 Comparator 61 Comparator 71 Copy lamp signal 72 Full-wave rectified waveform 73 Applied voltage 81 AC power supply 82 Shielding switch 83 Bidirectional thyristor (output adjustment element) 84 Lamp load 85 Control circuit 91 Control signal 92 Lamp state

Claims (4)

(57) [Claims] 1. A lighting control device for a copying machine in which a central processing circuit controls a voltage applied to a copy lamp to a copy lamp, wherein a voltage applied to the copy lamp when the copy lamp is turned on is detected.
And the detected copy lamp applied voltage is copied.
-If the rated voltage of the lamp is
A lighting control device comprising a lighting inhibition circuit for inhibiting a lamp . 2. The lighting control device according to claim 1, further comprising means for detecting a change in the input power supply, and means for switching the reference voltage of the lighting inhibition circuit to at least two levels based on the detection result. A lighting control device, characterized in that: 3. The lighting control device according to claim 1, wherein: a means for generating a full-wave rectified signal proportional to the input power; a means for integrating the full-wave rectified signal; A means for generating a lamp lighting prohibited area proportional to the lighting control device. 4. The lighting control device according to claim 1, wherein a means for generating a full-wave rectified signal proportional to the input power, a means for comparing the signal with a reference voltage, and an input power supply based on the signal output. Means for invalidating the lamp lighting signal only during a certain time period from the zero cross point of the waveform.