JPH04283782A - Controller for fixing device using exothermic element - Google Patents

Abstract

PURPOSE:To prevent malfunction due to a noise and to improve the reliability by providing a means which continues to count regardless of the invalidation of an abnormal state after the abnormal state continues for longer than a certain time and a means which stops feeding electricity to a fixation heater for the continuance of the abnormal state. CONSTITUTION:When an overheating state detection comparator 11 enters a current suction state, a transistor(TR) 127 turns off and a capacitor 128 for clocking is charged. When the potential of the capacitor 128 rises above the inverted input voltage of the comparator 12 for clocking, a TR 14 turns on and a TR 139 turns off to cut off a relay 106, thereby stopping the power supply to a fixing heater (not shown in figure). When the potential of the capacitor 128 rises above the certain voltage, a TR 16 turns on and a TR 127 turns off to charge the capacitor 128 continuously. Once the abnormal state continues for longer than the certain time, the relay 106 is held off continuously.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a fixing device that is used in image forming apparatuses and the like and has a heating element.

0002

2. Description of the Related Art Image forming apparatuses that visualize images stored in memory by fixing toner on printing paper are typified by laser beam printers and copying machines. Since then, it has been widely used.

A printing operation in an image forming apparatus is completed by making the toner visible on the printing paper through known electrophotographic techniques, that is, the processes of exposure, development, and transfer, and finally fixing the toner on the printing paper.

[0004] In the process of fixing toner on printing paper, a method using heat, a method using pressure, or a method using a combination of heat and pressure is selected.

If the heat fixing method is selected, there is a possibility of a fire accident occurring because the printing paper, which can become an ignitable substance, is heated, and ensuring safety in this case is a very important technique.

FIG. 7 shows a control circuit for a fuser heater including the circuit for ensuring safety (hereinafter referred to as a safety circuit).

In FIG. 7, reference numeral 103 denotes a fixing device consisting of a fixing heater 101, which is a heating means for printing paper, and a thermistor 102, which detects the temperature of the fixing heater.
04 inputs the temperature detected by the thermistor as a voltage value, and based on this result, it instructs the opening/closing of the triax 105, which is a heater energization control circuit, and when any abnormality occurs, it immediately switches on the relay 10, which is a heater energization cutoff circuit.
This is a CPU that controls 6. This control circuit also includes a current detection circuit that detects the heater current and is made up of a current transformer 107, an overheating state detection circuit that detects the overheating state of the heater and is made up of a comparator 108, and the CPU 1
It has a flip-flop 109 that stores and holds information that a current is detected even though the heater 04 is not outputting an energization instruction, or that an overheated state of the heater is detected.

[0008] The circuits of each part will be explained in detail below.

[0009] 103 is a fixing device, and the electrical parts are AC
It is composed of a heater 101 inserted into the primary circuit and a thermistor 102 that monitors the temperature of the heater 101. The thermistor 1 is connected by a voltage divider circuit with a fixed resistor 110
The resistance value of 02 is converted into a voltage value and input to the A/D conversion circuit. The figure shows a CPU 10 with a built-in A/D conversion circuit.
4 was used, but the A/D conversion circuit may be externally attached.

The CPU 104 knows the temperature of the heater 101 through the thermistor 102, and if the temperature is high, it stops firing the triac 105 to open the AC primary circuit, and if the temperature is low, it starts firing the triac 105. to close the AC primary circuit. This controls the heater 101 of the fixing device 103 to maintain a constant temperature.

[0011] The CPU 104 outputs a firing signal for the triac 105 from the port PORT2 output. When the ignition signal of the triax 105 is set to a HIGH or LOW level signal, the CPU 104 may run out of control, and the output may be fixed in a direction that continues to heat the fixing heater 101. To avoid this problem,
The firing signal of the triax 105 is made into a pulse.

That is, the CPU board on which the CPU 104 is mounted outputs an ignition signal using an open collector formed by a transistor 111. By using an open collector output, it becomes a measure against disconnection of the harness between the CPU board and the safety circuit. That is, by installing the pull-up resistor 112 on the safety circuit side, when the harness is disconnected, it is connected to the power supply line with low impedance, so that pulse-like noise is not superimposed on the signal line.

113 is a DC cut capacitor. As a result, when the CPU 104 runs out of control or the harness is disconnected, the signal that has reached the DC level can be cut off.

[0014] The next stage, a resistor 114, a diode 115,
The capacitor 116 is a rectifier/smoothing circuit, and is used to obtain the envelope of the pulse waveform.

The transistor 117 drives the LED of the photo try coupler 118 and discharges the charge from the capacitor 128 for measuring abnormal current flow.

Built-in L of photo try-out coupler 118
When ED lights up, triac 105 fires and AC
The primary circuit is closed. Note that by using a photo try-out coupler with a built-in zero-cross comparator as 118, it is possible to suppress the generation of noise at the time of firing the try-out.

Reference numeral 107 is a current transformer, and a current value proportional to the current of the AC primary circuit is obtained in the secondary winding. Next, the resistor 119 converts the secondary winding current value into a current/voltage.

Resistors 120, 121, 122, and 123 and comparators 124 and 125 constitute a window comparator. The comparators 124 and 125 have open collector outputs, and when the inverted input voltage exceeds the non-inverted input voltage, current is sucked from the output terminals. The two comparators 124 and 125 are wired-ORed, and a LOW level is created by a resistor 126. The window width is determined by the ratio of the four resistors,
If the input voltage of the comparator is above or below the window width, the output will be at a LOW level.

Transistor 127 is connected to capacitor 128
When the transistor 127 is OFF, the capacitor 128 is charged via the resistors 129 and 130. When transistor 127 is ON, capacitor 128 is discharged via resistor 130 and the transistor.

When the charging of the capacitor 128 progresses and the potential across the capacitor exceeds the sum of the base-emitter voltage of the transistor 131 and the Zener voltage of the Zener diode 132, the transistor 131 is turned on.

Further, the overheating state of the fixing heater is detected by the overheating state detection comparator 108, and the transistor 133 is turned off.

[0022] The transistor 133 is connected to the capacitor 134.
When the transistor 133 is OFF, the capacitor 134 is charged via the resistors 135 and 136. transistor 133
is ON, the capacitor 134 is discharged via the resistor 136 and the transistor 133.

When charging of the capacitor 134 progresses and the potential across the capacitor 134 exceeds the sum of the base-emitter voltage of the transistor 137 and the Zener voltage of the Zener diode 138, the transistor 137 is turned on.
do.

The reference time for checking the duration of the overheating state is determined by the capacitance value of the capacitor 134 and the resistance value of the resistors 135 and 136.
The resistance value of the zener diode 138 is determined by the zener voltage value of the zener diode 138. By optimizing these values, it is possible to build a system that ensures safety while improving noise resistance.

Flip-flop 109 is used only for setting, and transistor 131 is ON or transistor 1 is ON.
37 is turned ON, the memory is retained.

In other words, the CPU 104 controls the fixing heater 101.
The flip-flop 109 may be turned on due to either of the following reasons: the energization state continues for a certain period of time even though no energization instruction is output to the fuser heater 101, or the overheating state of the fixing heater 101 continues for a certain period of time or more. It remembers and retains the fact that it is in an abnormal state.

106 is a relay, and the transistor 13
When 9 is ON and transistor 140 is ON, current flows through the relay winding and the relay contacts close.

[0028] The port PORT1 output of the CPU 104 is set to H.
By setting it to IGH, the transistor 141 is turned on, and thereby the transistor 140 is turned on. CPU10
In No. 4, the fixing heater can be immediately shut off by setting the port 1 output to LOW after detecting that some kind of failure has occurred. Port PORT1 output HIGH
The reason why it is enabled is that when the port PORT1 output harness is disconnected, the base of transistor 141
This is because the resistor inserted in parallel between the emitters allows the relay contacts to open in the direction that is most safe.

When flip-flop 109 is set, transistor 139 is turned off and the relay contact is opened.

[0030]

However, in the above conventional example, the internal state of the flip-flop 109 is changed by a single set input, even though the occurrence of the abnormal state continues for a certain period of time or more. Because of this configuration, the stability of the flip-flop 109 was a factor determining the reliability of the safety circuit.

In other words, even though no abnormal state has occurred to the set input of the flip-flop 109 due to a single noise application or a fluctuation in the flip-flop power supply voltage, the flip-flop 10
9 was set, causing the relay 106 to be cut off.

Furthermore, in the conventional example described above, the CPU 104, which controls the triac opening/closing instructions and relay control, cannot directly know the state of the flip-flop 109, which stores and holds the abnormal state.

In other words, the CPU 104
Since the temperature did not rise despite outputting the energization instruction No. 5, it was indirectly recognized that the flip-flop 109 was set.

[0034] For this reason, there is a possibility that recognition of an abnormal state is delayed and a problem occurs in which prompt error processing cannot be performed. Further, even though the temperature was at an appropriate temperature at the time of paper feeding, the temperature dropped during fixing, so there was a possibility that print paper with insufficient fixation would be ejected.

[0035] In order to solve this problem, the CPU 10
Regarding 4, it is possible to add a signal line to report the flip-flop status, but if the safety circuit and CPU board are separate units, the number of harnesses would increase, which would increase the cost of the device. .

Furthermore, in the above conventional example, if it becomes impossible to cut off the current flow at the relay contact due to fusion of the relay contact or shorting between the collector and emitter of the transistor that is the relay winding energization switch, the device Ignition/
This could have led to smoke.

[0037]

[Means and effects for solving the problem] According to the present invention, without using a flip-flop with low noise resistance, after an abnormal state continues for a certain period of time or more, regardless of the invalidity of the abnormal state, time measurement is performed. Since the fixing heater is provided with a means for continuing to hold the fixing heater and a means for stopping energization to the fixing heater during the duration of the abnormal state, the memorized result of the abnormal state will not be changed by a single application of noise.

Further, according to the present invention, for the control means,
By providing a reporting means for reporting the memory retention result of an abnormal state, and a means for making the signal line for the reporting means also used as another control line, it is possible to report the abnormal state without increasing the number of harnesses. You can know directly about the occurrence.

Furthermore, according to the present invention, since the means for inhibiting the ignition of the triax during the duration of the overheating state of the fixing heater is provided, the energization of the fixing heater is prevented even by the triax during the overheating state. will be stopped.

[0040]

[Example] 1. In this example, the capacitor that measures the occurrence of the energization state when there is no instruction to energize the fusing heater and the capacitor that measures the overheating state of the fusing heater are combined into one capacitor, and the capacitor potential When the voltage exceeds a certain level, the relay is cut off and the capacitor continues to be charged.

FIG. 1 shows a safety circuit for explaining this embodiment.

[0042] In the figure, parts with the same numbers as those in the conventional example and other circuits not shown are the same as those in the conventional example, so explanations thereof will be omitted.

[0043] In the conventional example, the relay control signal is set to HI.
By setting it to GH, the transistor 141 is turned on and the PN
One side of the relay winding was driven by turning on the P transistor 140, but in this embodiment, the relay winding is driven only by the NPN transistor 139. This eliminates the need for a PNP transistor that requires a sufficient drive current, resulting in cost reduction.

The operation of the circuit shown in FIG. 1 will be explained below.

11 is an overheating state detection comparator;
Unlike the conventional comparator 108, since it is an open collector output, current will be sucked from the output when the non-inverting input voltage falls below the inverting input voltage (that is, when the temperature detected by the thermistor becomes abnormal). .

Window comparators 124 and 125, overheating state detection comparator 11, and transistor 1 to be described later
6 are wired-ORed, and when one of them becomes a current sink, it is pulled LOW by the pull-up resistor 126.
level, and the transistor 127 is turned off.

If all the wired-ORed elements do not sink current, these elements are equivalent to not being connected, and the transistor 127 is turned on by the pull-up resistor 126.

When the transistor 127 is OFF, the clock capacitor 1 is connected via the resistors 129 and 130.
28 is charged and the potential increases.

When the transistor 127 is on, the timekeeping capacitor 128 is discharged between the resistor 130 and the collector-emitter of the transistor 127.
The potential drops.

When the potential of the capacitor 128 (non-inverting input voltage of the comparator 12) is lower than the inverting input voltage of the time-keeping comparator 12, current is sucked from the output, and the pull-up resistor 13 turns it to LOW level, causing the transistor 14, 16 and 17 are turned off.

When the potential of the capacitor 128 rises and exceeds the inverted input voltage of the timekeeping comparator 12,
The output of the comparator 12 is electrically disconnected, and the pull-up resistor 13 turns on the transistors 14, 16, and 17.

Transistor 14 and transistor 15 are wired-ORed, and when either one is turned on, transistor 139 is turned off and relay 106 is cut off. Conversely, when both transistors 14 and 15 are turned off, transistor 139 is turned on and the contact of relay 106 is closed. Incidentally, the condition for transistor 15 to be turned off is that a CPU (not shown) drives a relay control signal and transistor 141 is turned on.

When the potential of the capacitor 128 rises and the transistor 16 turns on, the transistor 127 turns on and continues charging the capacitor 128.

In other words, through this loop, once the abnormal state continues for a certain period of time or more (if the potential of the capacitor 128 rises above a certain voltage), this state is maintained,
Thereafter, the relay 106 will continue to be cut off.

By driving the triac ignition signal in a pulsed manner, the open collector output of the comparator 18 is electrically disconnected, and the transistors 117 and 19 are turned off.
Do N. When the transistor 19 is turned on, the capacitor 128 is discharged. In this case, as in the conventional example, the triax 105 is fired and the current transformer 107 is turned on.
This is a consideration to prevent the relay 106 from being cut off during normal operation when the current is detected by.

However, once the abnormal state continues for a certain period of time, the transistor 17 is turned on, and the transistor 19 is turned on regardless of the output level of the comparator 18.
It becomes FF, and the capacitor 128 is not discharged.

2. In this embodiment, when there is no instruction to energize the fixing heater and the capacitor measures the occurrence of energization, when this potential exceeds a certain voltage, the relay is cut off and the capacitor is turned off. The configuration is such that charging continues.

FIG. 2 shows a safety circuit for realizing this embodiment.

The present embodiment has a configuration in which the overheating state detection comparator 11 in FIG. 1 is removed, and an abnormality is detected only when the energization state continues for a certain period of time even though there is no instruction to energize the fixing heater. It determines that there is one and shuts off the relay.

3. In this embodiment, in the capacitor that measures the overheating state of the fixing heater, when the potential of the capacitor exceeds a certain voltage, the relay is shut off and the capacitor continues to be charged.

FIG. 3 shows a safety circuit for realizing this embodiment.

In this embodiment, the current transformer 107 including the window comparators 124 and 125 in FIG.
This configuration eliminates the energizing current detection circuit in , and only when the overheating state of the fixing heater continues for a certain period of time, it is determined that there is an abnormality and the relay is shut off.

Incidentally, the transistors 17 and 19 are also omitted since they are unnecessary for this embodiment.

4. In this embodiment, the signal line for reporting the state of the flip-flop is used as the triac firing signal from the CPU board.

FIG. 4 shows a circuit for explaining this embodiment.

In the figure, a CPU 104, a transistor 111 for outputting a triac ignition signal, a pull-up resistor 112,
The flip-flop 109 and other circuits not shown are the same as those in the prior art example, so their explanation will be omitted.

Reference numeral 51 denotes a transistor, and when the flip-flop 109 is set to generate an abnormal state, the transistor 51 turns O
Do N.

Reference numeral 52 denotes a signal line, which becomes LOW level when the transistor 51 is turned on.

The CPU 104 receives the HIGH or LOW level of the signal line 52 from the port PORT3.

During normal operation, flip-flop 109
is not set, transistor 11 is OFF.
are doing. At this time, the presence of the transistor 11 does not affect other circuits, so the pulsed triac ignition signal sent from the CPU 104 becomes valid.

To check the state of the flip-flop 109, the CPU 104 first sets the port PORT2 to the LOW level, and then inputs the HIGH or LOW level of the signal line 52 from the port PORT3.

[0072] The CPU 104 turns the port PORT2 LOW.
By setting the level, the triac ignition signal output transistor 111 is turned off.

When the flip-flop 109 is not set in a normal state, the transistor 51 is turned off, and together with the fact that the transistor 111 is turned off, the pull-up resistor 112 causes the signal line 52 to go to the HIGH level. By inputting this level from the port PORT3, the CPU 104 recognizes that the safety circuit is in a normal state.

An abnormal state occurs and the flip-flop 109
is set, the transistor 51 is turned on,
Even though the transistor 111 is OFF, the signal line 52 is at a LOW level. Port this level to PO
By receiving the input from RT3, the CPU 104 recognizes that an abnormal state has occurred in the safety circuit.

Above, an example in which the input level of the port PORT3 is polled is shown, but when the input level of the port PORT3 is
It goes without saying that if the interrupt input is replaced with an OW active interrupt input, it becomes possible to recognize an abnormal state even more quickly.

5. In this embodiment, the relay control signal from the CPU board and the signal line for reporting the state of the flip-flop are used together.

FIG. 5 shows a circuit for explaining this embodiment.

In the figure, the CPU 104, the relay control transistor 141, the flip-flop 109, and other circuits not shown are the same as those in the conventional example, so their explanation will be omitted.

[0079] However, the port PORT1 of the CPU 104
The resistor connected between the base of the transistor 141 and the base of the transistor 141 is
Moved to the CPU board.

Reference numeral 21 denotes a transistor, which turns O when the flip-flop 109 is set to generate an abnormal state.
Do N.

Reference numeral 22 denotes a pull-up resistor, which guarantees a LOW level when the transistor 21 is turned on.

Reference numeral 23 denotes a signal line, which becomes LOW level when the transistor 21 is turned on.

The CPU 104 receives the HIGH or LOW level of the signal line 23 from the port PORT3.

During normal operation, flip-flop 109
is not set, transistor 21 is OFF.
are doing. At this time, the presence of the transistor 21 does not affect other circuits, so the relay control signal sent from the CPU 104 becomes valid.

To check the state of the flip-flop 109, the CPU 104 connects the signal line 23 to the HIGH level from the port PORT3 while keeping the port PORT1 at the HIGH level.
It is sufficient to input H or LOW level.

When the flip-flop 109 is not set in a normal state, the transistor 21 is OFF, but the port PORT1 of the CPU 104 is HIGH.
Since the signal line 23 is at a high level, the signal line 23 becomes a high level. By inputting this level from the port PORT3, the CPU 104 recognizes that the safety circuit is in a normal state.

When an abnormal state occurs and the flip-flop is set, the transistor 21 is turned on.
Although the port PORT1 of the CPU 104 is at a HIGH level, the signal line 23 is at a LOW level. By inputting this level from port PORT3, CP
U104 recognizes that an abnormal condition has occurred in the safety circuit.

[0088] Above, an embodiment in which the input level of the port PORT3 is polled is shown, but when the input level of the port PORT3 is polled,
It goes without saying that if the interrupt input is replaced with an OW active interrupt input, even faster recognition of the abnormal state becomes possible.

6. In this embodiment, the signal line indicating the temperature detection result from the CPU board and the signal line reporting the state of the flip-flop 109 are used.

FIG. 6 shows a circuit for explaining this embodiment.

In the figure, the CPU 104, the overheating state detection comparator 108, the pull-up resistor 110, the flip-flop 109, and other circuits not shown are the same as those in the prior art example, so their explanation will be omitted.

Reference numeral 31 denotes a transistor, which turns O when the flip-flop 109 is set to generate an abnormal state.
Do N.

During normal operation, flip-flop 109
is not set, transistor 31 is OFF.
are doing. At this time, the presence of transistor 31 does not affect other circuits.

An abnormal state occurs and the flip-flop 109
is set, the transistor 31 is turned on,
The input voltage of the A/D conversion circuit becomes approximately zero. This state is equivalent to the thermistor detecting an abnormal temperature, and the CPU 104 recognizes that an abnormal state has occurred in the safety circuit.

In this case, since the relay is shut off and the temperature does not gradually decrease, the CPU 104 does not need to track temperature changes and can quickly recognize the occurrence of an abnormal state.

Although the embodiment for checking the input voltage of the A/D conversion circuit has been described above, it goes without saying that if it is additionally connected to a LOW active interrupt input, it becomes possible to recognize an abnormal state even more quickly.

7. In this embodiment, when an overheating condition is detected, by connecting the input terminal of the triax firing signal from the CPU board to the ground line with low impedance,
Disables the pulsed triac firing signal.

FIG. 7 shows a control circuit for a photo try coupler LED for explaining this embodiment.

In the figure, a transistor 111 for outputting a triax ignition signal, a pull-up resistor 112, a capacitor 113 for cutting DC, a resistor 114 for rectification and smoothing, a diode 115, a capacitor 116, and a phototriax coupler L.
The ED driving transistor 117, the photo-triack coupler 118, the overheating state detection comparator 108, and other circuits (not shown) are the same as those in the conventional example, so their explanation will be omitted.

Reference numeral 61 denotes a transistor, which is turned off when the overheating state detection comparator 108 detects an overheating state of the fixing heater.

A transistor 62 is also turned on when the transistor 61 is turned off.

When the transistor 62 is turned on, the voltage at the triax firing signal input terminal becomes the saturated collector-emitter voltage of the transistor 62, and becomes almost zero, regardless of the triax firing signal from the CPU board via the transistor 111. Become. In other words, this is equivalent to connecting the triac ignition signal input terminal to the ground line with low impedance.

At this time, CP via the transistor 111
Even if a pulsed triax firing signal is sent from the U board, the triax firing signal becomes invalid and the phototriax coupler LED driving transistor 11
7 is turned off, and the built-in LED of the photo try-out coupler 118 does not light up, so the try-out does not ignite and the power supply to the fixing heater is stopped.

8. In this embodiment, when an overheating state is detected, the rectification and smoothing of the pulsed triac firing signal is disabled.

FIG. 8 shows a control circuit for the photo try coupler KED for explaining this embodiment.

In the figure, a pull-up resistor 112, a DC cut capacitor 113, a rectifying/smoothing resistor 114, a diode 115, a capacitor 116, a photo-triac coupler LED driving transistor 117, a photo-triac coupler 118, and an overheating state detection comparator. 108
Since the other circuits not shown are the same as those in the conventional example, their explanation will be omitted.

Further, the transistor 61 is the same as that of the seventh embodiment described above.
Since the functions are similar to those in FIG. 7, the same numbers as in FIG. 7 are given.

[0108] When the overheating state of the fixing heater is detected by the overheating state detection comparator 108, the transistor 61 is turned off and the transistor 21 is turned on.

When the transistor 21 turns on, the resistor 11
Since the current flowing through transistor 4 passes between the collector and emitter of transistor 21, it does not charge capacitor 116. Therefore, the potential of the capacitor 116 does not rise, and the photo-triack coupler LED driving transistor 117 is turned off.
Continuing to FF, the built-in L of the photo try-out coupler 118
Since the ED is not lit, the triac is not ignited and the fixing heater is also de-energized.

9. In this embodiment, when an overheating state is detected, the photo-triack coupler LED driving transistor is disabled.

FIG. 9 shows a control circuit for a photo try coupler LED for explaining this embodiment.

In the figure, a pull-up resistor 112, a DC cut capacitor 113, a rectifying/smoothing resistor 114, a diode 115, a capacitor 116, a photo-triac coupler LED driving transistor 117, a photo-triac coupler 118, and an overheating state detection comparator. 108
Since the other circuits not shown are the same as those in the conventional example, their explanations will be omitted.

Further, since the transistor 61 has the same function as in the seventh embodiment described above, it is given the same number as in FIG.

[0114] When the overheating state of the fixing heater is detected by the overheating state detection comparator 108, the transistor 61 is turned off and the transistor 31 is turned on.

When the transistor 31 is turned on, the photo try coupler LED driving transistor 117 is turned on.
Continuing to FF, the built-in L of the photo try-out coupler 118
Since the ED is not lit, the triac is not fired and the fixing heater is de-energized.

[0116] In each of the above embodiments, the overheating state is memorized and retained, but the relay may be cut off every time an overheating state is detected, and the relay may be restored when the overheating state is eliminated.

[0117] In any of the embodiments, in Examples 7 to 9, the power supply to the heater is cut off when the overheating state of the fixing heater continues for a certain period of time or more. It is also possible to prevent malfunctions caused by noise.

[0118]

[Effects of the Invention] As explained above, according to the present invention,
By providing a means for continuing to measure time after the abnormal state continues for a certain period of time or more, regardless of whether the abnormal state is invalid, and a means for stopping power supply to the fixing heater while the abnormal state continues, The memorized result of the abnormal state is not changed by a single noise application, and the malfunction of the relay cutoff during normal operation is eliminated, thereby achieving the effect of significantly improving the reliability of the fixing device control device.

Further, according to the present invention, for the control means,
By providing a means for reporting the memory retention result of an abnormal state and a means for making the signal line for the reporting means also used as another control line, it is possible to prevent the occurrence of an abnormal state without increasing the number of harnesses. , it is possible to directly know the problems, while suppressing the increase in equipment costs. 1) Rapid failure recognition and error handling 2) Preventing problems where print paper with insufficient fixation is ejected. The effect of

Further, according to the present invention, since the means for inhibiting the ignition of the triax while the fixing heater is in an overheated state is provided, the power supply to the fixing heater can be prevented even by the triax during the overheating state. is stopped, so
Even if it becomes impossible to cut off the current using the relay, it is possible to prevent the device from igniting or emitting smoke.

[Brief explanation of the drawing]

FIG. 1 is an electrical circuit diagram showing the configuration of a first embodiment of the present invention.

FIG. 2 is an electric circuit diagram showing the configuration of a second embodiment of the present invention.

FIG. 3 is an electrical circuit diagram showing the configuration of a third embodiment of the present invention.

FIG. 4 is an electric circuit diagram showing the main part configuration of a fourth embodiment of the present invention.

FIG. 5 is an electric circuit diagram showing the main part configuration of a fifth embodiment of the present invention.

FIG. 6 is an electric circuit diagram showing the main part configuration of a sixth embodiment of the present invention.

FIG. 7 is an electric circuit diagram showing the main part configuration of a seventh embodiment of the present invention.

FIG. 8 is an electric circuit diagram showing the main part configuration of an eighth embodiment of the present invention.

FIG. 9 is an electric circuit diagram showing the main part configuration of a ninth embodiment of the present invention.

FIG. 10 is an electrical circuit diagram showing the configuration of a conventional fixing device control device.

[Explanation of symbols]

11, 12, 18, 108, 124, 125 Comparators 13, 22, 112, 114, 119-123, 126
, 129, 130 Resistors 14-17, 19, 21, 31, 51, 61, 62, 1
11, 117, 127, 139, 141 Transistor 105 Triack 106 Relay 107 Current transformer 109 Flip-flop 113, 116, 128 Capacitor 115 Diode 118 Phototriack coupler

Claims (8)

[Claims] 1. A device for controlling a fixing device for fixing an image formed on a sheet by a developer using a heating element, the device comprising: a detection means for detecting an abnormality in the fixing device; and a detection device for detecting an abnormality in the fixing device; a clocking means for increasing the clocking time in a state in which the means detects an abnormality and decreasing the increased clocking time in a state in which the detecting means does not detect an abnormality, and a clocking time of the clocking means to a predetermined value. a cutoff means for cutting off the power supply to the heat generating element when the timer reaches a predetermined value; 1. A control device for a fixing device using a heating element, comprising a forcing means for forcing the time to increase. 2. The control device according to claim 1,
The detecting means includes a temperature detecting means for detecting the temperature of the heat generating element, and a determining means for determining that the fixing device is abnormal when the temperature detecting means detects an overheated state of the heat generating element. A control device characterized by: 3. The control device according to claim 1,
The detection means includes a current detection means for detecting a current flowing to the heat generating element, and when the current detection means detects a state of energization to the heat generating element when there is no instruction to energize the heat generating element; and determining means for determining that the fixing device is abnormal. 4. A device for controlling a fixing device for fixing an image formed on a sheet by a developer using a heat generating element, comprising: a control means for controlling energization to the heat generating element; a detection means for detecting an abnormality in the fixing device; a holding means for storing a state in which the abnormality is detected by the detection means for a predetermined period of time; and a notification of the storage result of the holding means to the control means. 1. A control device comprising a notification means for communicating a control signal from the control means and a signal from the notification means using the same signal line. 5. A device for controlling a fixing device for fixing an image formed on a sheet by a developer using a heat generating element, comprising: temperature detection means for detecting the temperature of the heat generating element; control means for instructing energization of the heating element based on a detection output from the temperature detection means; energization control means for controlling opening/closing of an energization circuit to the heating element based on the energization instruction from the control means; determining means for determining the overheating state of the heat generating element based on the detection output of the detecting means; 1. A control device for a fixing device using a heat generating element, comprising: forcing means for forcing the energization circuit into an open state by means of energization control means. 6. A heating means for thermally fixing a recording medium onto a printing paper, a temperature detection means for detecting the temperature of the heating means, and an instruction to energize the heating means based on a detection result of the temperature detection means. energization control means for controlling energization to the heating means depending on the presence or absence of an energization instruction from the control means; current detection means for detecting the energization current to the heating means; A first determining means determines that the heating means is in an abnormal state when the current detecting means detects an energization state when there is no energization instruction; a second determining means for determining the duration of the abnormal state determined by the first or second determining means; In an image forming apparatus, the image forming apparatus includes a means for setting the counting means in a decreasing direction when there is no abnormal state, and a comparing means for determining that the counted value of the counting means has exceeded a certain value, wherein the comparing means is compared. means for setting the counting means in an increasing direction depending on the result, regardless of the judgment result of the first or second judgment means;
An image forming apparatus comprising: an energization cutoff means for cutting off energization to the heating means according to a comparison result of the comparison means. 7. A heating means for thermally fixing a recording medium to a printing paper, a temperature detection means for detecting the temperature of the heating means, and an instruction to energize the heating means based on a detection result of the temperature detection means. an energization control means for controlling energization to the heating means depending on the presence or absence of an energization instruction from the control means; a current detection means for detecting the energization current to the heating means; Abnormal temperature is detected based on the detection result of the temperature detection means and a first determination means that determines that an abnormal state is present when the current detection means detects that the heating means is energized even though there is no energization instruction. a second determining means for determining that the heating means is in an overheating state when By the means for storing the continuation and the result of storing the continuation,
In the image forming apparatus, the image forming apparatus includes a current cutoff means for stopping power supply to the heating means, a reporting means for reporting the memory retention result to the control means, and a signal line for the reporting means connected to another An image forming apparatus characterized by comprising means for serving also as a control line. 8. A heating means for thermally fixing a recording medium onto a printing paper, a temperature detection means for detecting the temperature of the heating means, and an instruction to energize the heating means based on a detection result of the temperature detection means. a control means for controlling the opening and closing of the energized circuit depending on the presence or absence of an energization instruction from the control means; a current detection means for detecting the energization current by the control means; and no energization instruction for the heating means. Nevertheless, an abnormality detecting means detects the occurrence of an abnormal state in which electricity is applied, a determining means determines an overheating state that is an abnormal temperature based on the temperature detection result of the heating means, and a timer for confirming that at least one of the overheating conditions continues for a predetermined period of time; a retention means for storing and retaining the continuation of the abnormal condition or the overheating condition; 1. An image forming apparatus having an energization cutoff means for stopping energization, characterized in that the image forming apparatus is further provided with means for fixing the energization circuit opening/closing control means in an open state during the duration of the overheating state.