JPS61210407A - Abnormal detecting system for high voltage electric power source device - Google Patents

Abstract

PURPOSE:To discriminate an abnormal condition without fail by judging that the abnormality occurs when the normal scope of the output power is set and the detected output power exceeds the setting scope. CONSTITUTION:When a high voltage power source enters the prescribed scope and a signal V1 is located at the scope from a graphic display VR1 to a VR2, an output signal DE of a window comparator 12 is an L level at the timing at which a timing signal TM is raised, and therefore, a signal OE goes to the L level and the usual control is executed. On the other hand, the power of the high voltage power source is not sufficiently outputted and an current signal Id does not go to be the prescribed value or above, the signal V1 is not located at the scope from the VR1 to the VR2, and therefore, the signal DE goes to be a H level and the signal OE rises to the H level. Thus, a control circuit 4 limits or stops the output, and it is discriminated at the main body control part that the abnormality occurs at a charger 101 part. When the over-load condition is obtained and the output goes to be an overcurrent, the abnormality is also discriminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an abnormality detection method for a high-voltage power supply device that detects an abnormality in a high-voltage generating section or the like of a copying machine.

[Prior Art] In devices equipped with a high-voltage power supply, such as a copying machine, the state of the high-voltage power supply is monitored to determine when a part using high voltage becomes abnormal.

Taking a copying machine as an example, if a person touches a high-voltage part or the output contacts the ground, causing a short circuit, the high-voltage part, such as the charger, may experience intermittent or continuous abnormal discharge.
If this condition continues, or if the thin wire that is the discharge electrode of the charger is disconnected and becomes a no-load or short-circuit condition, if the insulation of the charger block deteriorates and leakage current increases, or furthermore, This is the case when the transfer paper or a piece of the transfer paper has entered the charger, or when the paper dust or toner accumulated in the charger is moist.

Conventionally, in order to deal with such various abnormalities, constant voltage control types detect overcurrent, and constant current control types detect overvoltage and limit or cut off the output to prevent accidents. ing. Furthermore, it is possible to increase the output resistance of the high voltage power supply and connect a resistor between the power supply output and the load to prevent the power supply from being destroyed when there is no load.
The output is limited or cut off when the output current exceeds a predetermined short-time abnormal setting value or when the intermittent current exceeds a predetermined value and the frequency thereof exceeds a predetermined value within a predetermined time.

However, even with this conventional method, it is not possible to deal with the above-mentioned abnormalities such as transfer paper or pieces of it entering the charger, or situations where paper dust or toner accumulated in the charger is moist. The problem was that I couldn't do it.

[Objective] The present invention has been made to solve the above-mentioned disadvantages of the conventional technology, and an object of the present invention is to provide an abnormality detection method for a high-voltage power supply device that can reliably determine an abnormal state.

[Configuration] In order to achieve this objective, the present invention sets a normal range of output power, and determines that an abnormality has occurred when the detected output power exceeds this set range. .

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a high voltage power supply device according to an embodiment of the present invention. In this embodiment, a photoreceptor 100 is used in a copying machine.
This is a device that drives a charger (scorotron) 101 that charges .

In the same figure, the primary side circuit of transformer 1 is
It consists of a main transistor 3 that switches the primary winding 1a to which is connected, and a control circuit 4 that drives the main transistor 3 and controls the output at a constant voltage.

The secondary circuit of the transformer 1 includes a diode 5 that rectifies the voltage generated in the secondary winding 1b, a smoothing capacitor 6 that smoothes the rectified output, voltage dividing resistors 7 and 8 that detects the output voltage,
Output resistance9. It consists of a filter lO consisting of a capacitor and a resistor, and a voltage dividing signal Vd is generated by a voltage dividing resistor 7°8.
The current signal (feedback current) Id output from the filter 10 is fed back to the control circuit 4, respectively. Thereby, the control circuit 4 controls the duty of the main transistor 3 so that the divided voltage signal Vd becomes a predetermined value, and as a result, the output voltage is controlled to the set value. Also,
The control circuit 4 monitors the state of the current signal 1d.

Further, the current signal Id is converted into a voltage signal v1 by the voltage follower circuit 11, and this voltage signal v1 is
added to the window comparator 12.

The window comparator 12 has input resistors 12a and 12b.
, operational amplifiers 12c and 12d, upper limit value VRI and lower limit value V
Reference voltage setters 12e and 12f that respectively set R2
, and diodes 12g and 12h forming an OR circuit of the outputs of the operational amplifiers 12c and 12d.
When the range (VRI-VB2) set by g and 12f is exceeded, the output signal OE is raised to the logic IK level.

The output signal DB of this window comparator 12 is.

The AND circuit 13 is connected to one input terminal of the AND circuit 13.
When the timing signal TM applied to the other input terminal rises and the AND circuit 13 becomes operational, the signal DH is outputted as the signal ODE to the control circuit 4 and the main body control section.

Further, when the lighting command signal Do is output from the main body control section and the switch 14 is turned on, the control circuit 4 starts driving control of the main transistor 3, and further, when the signal OE is raised, the output voltage is forcibly set to a predetermined value. reduce the voltage to a low level.

In this embodiment, it is determined whether the current signal Id is within a predetermined range, but considering that the control circuit 4 performs constant voltage control, it is determined whether the output power is within a predetermined range. This is equivalent to determining the .

With the above configuration, the main body controller 1 raises the lighting control signal DO at a predetermined timing as shown in FIG. 2(a), and also raises the timing signal TM as shown in FIG. 2(b).
Output. In this case, the 1 lighting control signal 00 is raised, the control circuit 4 starts operating, and the main transistor 3
Since there is a slight time delay between the start of on/off driving and the actual generation of the high-voltage power supply, the timing signal TM rises a little later than the lighting control signal Do.

Therefore, when the high voltage power supply is within a predetermined range, the signal v1 is within the VRI as shown as part P1 in FIG.
to VB2, the timing signal TM
At the timing when OE rises, the output signal 1)E of the window comparator 12 is at a logic level, so the signal OE
becomes the logic L level (see (d) in the same figure), and normal control is performed.

On the other hand, the high voltage power supply does not output enough power, and the current signal I
If d does not exceed the predetermined value, the signal v1 is not within the range from VRI to VH2 as shown in part P2, so the output signal DH of the window comparator 12 becomes a logic H level, and therefore the timing signal TM rises. The signal OE rises to the logic H level at the timing determined by the signal.

As a result, the control circuit 4 limits or stops the output, and the main body control unit determines that an abnormality has occurred in the charger 101 portion.

Note that when an overload condition occurs and the output becomes an overcurrent condition, the signal v1 becomes larger than the predetermined range, so
Abnormality detection is performed in the same manner as described above.

In this way, if the output power deviates from the predetermined range,
This is determined by the control circuit and main unit control unit as an abnormality, and the control circuit limits or stops the output of the high voltage power supply, and the main unit control unit determines that an abnormality has occurred in the high voltage section, and takes predetermined measures (for example, copying (stopping the process).

FIG. 3 shows another embodiment of the invention.

In this embodiment, voltage information and current information of high-voltage output are detected, power information is calculated based on them, and it is determined whether the calculation result is within a predetermined range. In addition,
In this figure, the same parts as in FIG. 1 are given the same reference numerals, and their explanation will be omitted.

In the figure, voltage signal Vd and current signal Id are applied to multiplication circuit 20 and multiplied, and the result is output to window comparator 12 as power detection signal Pd.

This multiplier circuit 20 includes an analog multiplier 20a, an operational amplifier 20b, and resistors 20c, 20d, 20e, 20
f, 20g.

It consists of 20h, 20i, 20j, 20k, and the resistance value of resistor 20 is RO, and the resistance value of resistor 20c, 20
The resistance values of resistors d, 20i, and 20j are set to R1, and the resistance values of resistors 20e, 20f, 20g, and 20h are set to R2. At this time, the power detection signal Pd, which is the output signal, is generated by the current signal 1d and the voltage signal Vd, which are the input signals, according to a linear equation.

Pd=(VdId)/10 Furthermore, the setting range of the window comparator 12 is set to the allowable range of the set output (rated output) of this power detection signal Pd.6 For example, in the case of a copying machine, the allowable power range is ,
Since it is set to approximately ±40% of the rated power, the setting range of the window comparator 12 is also set accordingly.

Note that since the operation of this embodiment is the same as that of the above-mentioned embodiment, the explanation thereof will be omitted.

FIG. 4 shows yet another embodiment of the present invention. In this embodiment, the control circuit 4 controls the output power supply with a constant current, and the LSI device [! Tex to 4a
A semiconductor device called Tl2O3 manufactured by AS Instruments is used. In this figure, the same parts as in FIG. 1 are given the same reference numerals, and their explanations will be omitted.

In the figure, the voltage signal Vd is applied to the window comparator 1.
2, and it is determined whether the range of the value exceeds a predetermined value. Further, the current signal Id is the control circuit 4
An error from a predetermined value is detected, and the duty of the main transistor 3 is controlled in accordance with the detected value, and as a result, the output current is controlled to a predetermined value.

Furthermore, when the signal OE is raised, the control circuit 4 limits or stops the output to prevent an accident from occurring.

Figure 5 is an LSI device! 4a shows internal functional blocks. This LSI device! 4a is a device that basically drives the main transistor 3 by PvM (Hals width modulation), and its oscillation frequency is determined by the resistance value of the resistor connected to the terminal RT of the oscillator O8 that generates the sawtooth wave and the terminal It is set by the capacitance of the capacitor connected to CT.

The output of this oscillator O8 is connected to a comparator CP1, in which a dead time setting voltage applied from a terminal DT is added to the comparison terminal to set the dead time, and two error amplifiers OA1. The output of OA2 is applied to the reference input terminal of comparator CP2, which is applied to the comparison input terminal.

Note that terminals IVI and IV2 are error amplifiers OAI and OA.
The inverting input terminal of the terminal 2 is connected to the terminal NII, and the non-inverting input terminal is connected to the terminal NI2, respectively, and the error amplifier OAI
.

The output end of OA2 is connected to terminal FB and drawn out to the outside. Therefore, by using an external circuit, the error amplifier O
Arbitrary characteristics are assigned to AI and OA2.

The outputs of these comparators CPI and CP2 are then sent to the steering flip-flop F via an OR circuit OR.
Trigger input terminal of F and output transistor Ql.

It is input to one end of the NOR circuits NRI and NR2 that drive Q2.

The output of the steering flip-flop FF is applied to one end of the AND circuit ADI, AD2, to which the signal input from the input terminal OC is applied, and the output of these AND circuits ADI, AD2 is applied to the NOR circuit NRI, NR2. is applied to the other end.

Further, this Tl2O3 has a built-in reference voltage generator RV, which stabilizes the voltage input to the terminal Vcc to generate a reference voltage, supplies it to the internal circuit, and outputs it to the outside from the terminal Vr. Note that the terminal GND is an external ground terminal, and the terminals CI and C2 have output transistors Ql and
The collector of Q2 is connected to the terminals El and E2, respectively, to the emitter.

Therefore, when the oscillator O5 is outputting a sawtooth wave SO as shown in FIG. 6(a), and the signal Sl is applied as the comparison input of the comparator CP2, the output transistors Ql and Q2 are , respectively in the same figure (
b) It operates on and off as shown in (c).

In this way, the main transistor 3 is turned on and off by the LSI device 4a, the output current is controlled to fall within a predetermined tolerance range from the rated value, and the signal O
When H is raised, the duty of the main transistor 3 is reduced to 0, and the output of the high voltage power supply is stopped.

As described above, if the output power of the high voltage power supply is not within the specified tolerance range from the rated value, it is determined that some kind of abnormality has occurred in the high voltage section, and the output of the high voltage power supply is restricted or stopped. Therefore, it is possible to reliably detect events that could not be determined as abnormalities in the past, and improve the reliability of the device.

In the above embodiment, the output power of the high-voltage power supply is determined by an analog circuit, but the determination device is not limited to this. For example, the detection signal may be converted into a digital signal by an analog/digital converter. , output power can be determined by arithmetic processing by a microcomputer.

[Effects] As explained above, according to the present invention, a normal range of output power is set, and when the detected output power exceeds this set range, it is determined that an abnormality has occurred. Therefore, there is an advantage that an abnormal state can be reliably determined.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a device according to an embodiment of the present invention, FIGS. 2(a) to (d) are waveform diagrams for explaining the operation of the device shown in FIG. 1, and FIG. is a circuit diagram showing a device according to another embodiment of the present invention, FIG. 4 is a circuit diagram showing a device according to still another embodiment of the present invention, and FIG. A block diagram showing an example of an LSI device constituting a control circuit, and FIGS. 6(a) to 6(c) are waveform diagrams for explaining the operation of the LSI device shown in FIG. l...Transformer, 4...Control circuit, 4a...LS
I device, 1.8... voltage dividing resistor, lO... filter,
11... Voltage follower circuit, 12... Window comparator. 13...AND circuit, 14...switch, 2o...
・Multiplication circuit.

Claims (1)

[Claims] In an abnormality detection method for a high-voltage power supply device that controls the output voltage or output current to a predetermined value, a power detection means for detecting output power and a detection means for detecting that the detected output of the power detection means exceeds a predetermined range. An abnormality detection method for a high-voltage power supply device, characterized in that the output voltage or output current is limited or stopped based on the output of the detection means.