JPS63104870A - Image forming device - Google Patents

Abstract

PURPOSE:To enable the result of self-diagnosis to be securely maintained for a long time when a main power source is OFF, by providing a nonvolatile storage means for storing the result of detection of inability to form an image in an image forming device having a self-diagnosing function, and a means for judging the start of an image forming operation when a power source is turned ON, according to data stored in the storage means. CONSTITUTION:An EEPROM 27 is a nonvolatile memory capable of being written and erased by electrical signals, and comprises various flag registers having, for example, alarm flags 17a', 18a', 19a' turned from logic '0' to logic '1' when signals indicating the respective breakage of thermistors 17a, 18a, 19a are inputted, alarm flags 17b', 18b', 19b' turned from logic '0' to logic '1' when signals indicating the respective breakage of heaters 17b, 18b, 19b are inputted, and an alarm flag 14, indicating that a motor 14 is not in normal rotation. When any one of the alarm flags is set to '1' as a result of self- diagnosis, an abnormal state of the device is displayed. The data are securely maintained in the EEPROM 27 even when a main power source is turned OFF, until the power source is returned ON.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an image forming apparatus such as an electrophotographic copying machine or various printers, and in particular, to a so-called self-diagnosis function that allows the apparatus to confirm the readiness state of image formation by itself. The present invention relates to an image forming apparatus having the present invention.

[Traditional technique]

As an image forming apparatus, for example, a liquid crystal printer has a charger, an optical writing section,
A developing device, a transfer device, etc. are provided, and image information is written onto the circumferential surface of the photoreceptor drum, which is uniformly charged by a charger, from an optical writing section consisting of a light source such as a fluorescent lamp and a liquid crystal shutter. Perform exposure including After forming an electrostatic latent image on the circumferential surface of the photoreceptor drum, the electrostatic latent image is further developed using a developing device, and the developed image (toner image) is transferred to plain paper via a transfer device for use. 1E
Il! This is a device that obtains an image on plain paper by thermally fixing it using a thermal fixing device located on the feeding path.

Since such a liquid crystal printer performs the above-mentioned image formation, before starting image formation, it is checked whether the image forming members such as the photoreceptor drum, the light source in the optical writing section, the liquid crystal cell, the thermal fixing device, etc. are ready for image formation. It has a self-diagnosis function to check.

A specific example of this self-diagnosis function is, for example, when detecting disconnection of a thermistor that detects that the above-mentioned light source, liquid crystal cell, heat fixing device, etc. must reach a predetermined temperature before image formation. This is also a case of detecting a disconnection of a heater that heats and maintains the above-mentioned light source or the like at a predetermined temperature. Also, one of the self-diagnosis functions is to check whether a motor that rotates a rotating body such as a photoreceptor drum is rotating at a predetermined speed.

Conventionally, image forming apparatuses such as liquid crystal printers that have such a self-diagnosis function start image forming operations by determining data of self-diagnosis results such as the above-mentioned thermistor disconnection detection results.
Some devices control stoppage, but do not have the function of storing and retaining the above-mentioned self-diagnosis result data when the main power of the device is turned off.

On the other hand, a charging/discharging circuit of a capacitor and a resistor is provided in the image forming apparatus, and when the main power is turned off, the charge stored in the capacitor is discharged through the resistor, thereby retaining the data of the self-diagnosis results for a certain period of time. Image forming devices have also been used.

Furthermore, as an image forming apparatus that retains data on self-diagnosis results, the data on self-diagnosis results is stored in a storage element such as a volatile memory such as a RAM, and when the main power is turned off, the above-mentioned storage element is stored in a storage element such as a battery when the main power is turned off. Image forming apparatuses that retain stored contents are also used.

[Problems with conventional technology]

As mentioned above, there are two types of conventional image forming apparatuses: those that cannot retain the data of their self-diagnosis results when the power is turned off, and those that can retain the data, but each has the following problems. .

b) Image forming apparatuses that cannot retain self-diagnosis result data when the main power is turned off will perform self-diagnosis processing such as thermistor and heater disconnection detection, motor rotation speed detection, etc., when the main power is turned on again. Therefore, it takes a long time to start image formation after turning on the main power. for example,
Heater disconnection detection as described above usually involves determining whether the control signal to the heater switches (from high level to low level, or from low level to high level) within a certain period of time after the main power is turned on. It is being done. For this reason, heater disconnection cannot be detected until a certain period of time has passed after the main power is turned on. Therefore, it takes time to start the image forming operation.

In addition to this problem, if the main power source is repeatedly turned on and off even when image formation is not possible, it will adversely affect the apparatus. For example, if this heater is for heating a light source, even if a disconnection of this heater is detected when the main power is turned on, if the main power is turned on and off (repeatedly), if the ambient temperature is high, the The temperature of the tube wall of the light lamp may rise to the ready temperature. After this, the fluorescent lamp turns off as it reaches the ready temperature. It remains in this state for a long time (
If the printer is left in an idle state (no printing operation is performed), the fluorescent lamp heater will be disconnected and the temperature of the fluorescent lamp will drop rapidly, resulting in an insufficient amount of light from the fluorescent lamp during printing.

(7) Image forming devices that use a charging/discharging circuit using a capacitor and a resistor as an image forming device capable of retaining data on self-diagnosis results are fine as long as the main power is turned off for a short period of time, but if the period of time when the main power is turned off is prolonged, the charge stored in the capacitor will increase. There are also limits to
If the main power remains off for a long period of time, the charge in the capacitor will be completely discharged and the above data cannot be retained.

c) Furthermore, in an image forming apparatus that uses a battery as an image forming apparatus that can retain data of self-diagnosis results, the same problem as mentioned above occurs when the battery reaches the end of its life.
When connecting the battery to the circuit (when using the battery) or disconnecting the battery from the circuit, a special sequence circuit is required to stabilize the voltage supplied to the RAM, which increases the cost of the device.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the above-mentioned conventional drawbacks, it is an object of the present invention to provide an image forming apparatus that reliably retains data of self-diagnosis results for a long time when the main power is turned off, and does not increase the cost of the apparatus.

[Key points of the invention]

In order to achieve the above object, the present invention provides an image forming apparatus having a self-diagnosis function that detects an image formation impossible state inside the apparatus and prohibits image forming operation based on the detection result.
The apparatus further comprises: a writable and erasable nonvolatile storage means for storing a detection result of a state in which image formation is not possible in the apparatus; and a determination means for determining whether to start an image forming operation when the power is turned on according to data stored in the storage means. Features.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a diagram showing a schematic configuration of a liquid crystal printer as an image forming apparatus of the present invention having a self-diagnosis function.

In the figure, the inside of the liquid crystal printer 1 includes a photosensitive drum 2 for forming an image, a charger 3, a print head 4, and a developer rj.
I5, a transfer device 6, a cleaning device (cleaner) 7, a paper feed roller 9 disposed on a conveyance path 8 for conveying the paper P, a standby roll 10, a separation conveyance roll 11, a fixing device 12, and a paper discharge It is composed of a roll 13 and the like, and furthermore, a motor 14 for rotating the above-mentioned photosensitive drum 2 and various rolls 10, 11, etc. is disposed at a predetermined location.

A paper feed cassette 15 for storing the above-mentioned paper P is provided at the bottom of the liquid crystal printer 1, and a paper ejection tray 16 is provided at the side for ejecting the paper P on which an image has been formed in the liquid crystal printer 1. There is.

Further, a fluorescent lamp 17 is provided as a light source in the print head 4 described above.
A liquid crystal shutter 18 is provided at a position where the light from the fluorescent lamp 17 is irradiated.

The fluorescent lamp 17 and the liquid crystal shutter 18 must each reach a predetermined temperature during image formation, which will be described later, and each is equipped with thermistors 17a and 18a for temperature detection and heaters 17b and 18b for heating. It is provided.

Further, the fixing device 12 includes a lower roll 19 and a driven roll 2.
The lower roll 19 is provided with a thermistor 19a1 for detecting the surface temperature of the lower roll 19 and a heater 19b for heating the lower roll 19.

The liquid crystal printer 1 having such a mechanical configuration is provided with a control circuit 21 shown in FIG. 1 at a location not shown. This control circuit 21 includes a main controller 22 for controlling all of the liquid crystal printer 1 of this embodiment, a print head controller 23 for controlling the print head 4 described above, the fixing device 12 described above, the motor 14, It is composed of a fluorescent lamp 17, a liquid crystal shutter 18, and the like.

The main controller 22 has the liquid crystal printer 1 of this example inside.
A ROM 24 that stores a system program, a RAM 25 that stores various data such as flag data and counter data (described later) during image forming operation or standby, a CPU 26 that controls the apparatus according to the system program in the ROM 24, and an EEFROM (described later). It consists of an electrically erasable programmable ROM) 27, a gate array 28, a logic IC 29, and a dip switch 30.

The EEFROM 27 is a nonvolatile memory that can be written to and erased by electrical signals, and is composed of various flag registers. For example, alarm flags 17a', 18a', which change from logic "0" to "1" (hereinafter expressed as "0" → "1") when the thermistors 17a, 18a, 19a are disconnected and this signal is input, 19a', heater 17b1
When 18b and 19b are disconnected and this signal is input, the alarm flags 17b' and 1 change from logic "0" to 11.
8b', 19b', and an alarm flag 14' indicating that the motor 14 is not rotating normally. Also, R.A.
Inside M25, there is a safety flag 38' for prohibiting the operation of loads such as heaters and motors that are dangerous if they operate when an abnormality occurs, a fluorescent lamp 17, a liquid crystal shutter 18, and a fixing device 12.
When preparation for starting image formation is completed, logic “0” → “1”
” when ready flags 17', is', 12' and all ready flags are "1", logic "0" - "1"
It has an area for a warm-up completion flag 39', and also includes an area for a motor lock counter that confirms that the motor 14 is rotating at a predetermined number of revolutions together with the CPU 26, and a timer set for a predetermined time.

The main controller 22 having the RAM 25 and EEFROM 27 configured as above is the print head controller 2.
3. Input section 31 such as various switches and sensors, high pressure unit 32, output section 33 such as solenoids and relaunch, motor controller 34, fixing temperature control section 35, key human power section 36,
It is connected to a display section 37 and an external computer (not shown).

On the other hand, the print head controller 23 is connected to the main controller 22 described above, and also includes a fluorescent lamp 17, a liquid crystal shutter 18, and a thermistor 17a.

18a1 Heater 17bS 18b, Photo sensor 17c
It is connected to the.

Although not shown in the print head controller 23, there is a lighting circuit for the fluorescent lamp 17, a fluorescent lamp temperature control circuit for maintaining the tube wall temperature of the fluorescent lamp 17 at a predetermined temperature, and a liquid crystal shutter 18.
A liquid crystal shutter drive control circuit for controlling the opening and closing of a micro-shutter (not shown) inside, a liquid crystal shutter temperature control circuit for maintaining the temperature of the liquid crystal shutter 18 at a predetermined temperature, etc. are built in. Furthermore, a disconnection detection circuit for detecting disconnection of the thermistors 17a and 18a is also included.

The fluorescent lamp temperature control circuit and the liquid crystal shutter temperature control circuit determine whether the fluorescent lamp 17 and the liquid crystal shutter 18 have reached a predetermined temperature based on the temperature detection output of the thermistor 17a118a attached to each, and determine whether the predetermined temperature is reached. For example, in order to maintain the temperature, each heater 17b, 18
b) Outputs the heater on/off control signal, and simultaneously sends this predetermined temperature detection signal and heater on/off control signal to the main controller 22.
Outputs an off signal. This signal causes the aforementioned RAM25
The ready flags 17' and 18' in the logic “
0"-"1". Also, in the disconnection detection circuit, when the thermistors 17a and 18a are disconnected, a disconnection detection signal is output to the main controller 22, and each alarm flag 17a' and 18a' in the EEFROM 27 is set to logic as described above. “0”
−1″.

On the other hand, the main controller 22 receives various signals from sources other than the print/rad controller 23, such as control signals and image video signals from a computer.
Various detection signals (detection signals not related to the above-mentioned fluorescent lamp 17, liquid crystal shutter 18, fuser 12, and motor 14) are input from the input unit 31, and a signal indicating whether the motor 14, which will be described later, is rotating is input from the motor controller 34. enters,
A signal, which will be described later, is input from the fixing temperature control circuit 35, and an operator operation signal is input from the key power section 36.

Further, the motor controller 34 is connected to the aforementioned motor 14 and an encoder 14a that is attached to the rotation shaft (not shown) of the motor 14 and detects the rotation of the motor.A motor drive command signal is input from the CPU 26 in the main controller 22, and the encoder 14a Motor 14 detected by
A detection signal indicating the non-rotating state is output to the CPU 26.

Further, the fixing temperature control unit 35 is connected to the thermistor 19a and the heater 19b, and in order to maintain the temperature of the user roll 19 at a predetermined temperature, the fixing temperature controller 35 adjusts the temperature of the fuser 12 (the heater 19) according to the output of the thermistor 19a. ) and a disconnection detection circuit for the thermistor 19a, which sends an on/off signal for the fuser to the main controller 22, a predetermined temperature detection signal, and a disconnection detection circuit. Output a signal. In the main controller 22, when the above-mentioned predetermined temperature detection signal is input, the RA
When the ready flag 12' in M25 is set to logic "0" - 1 and the above-mentioned disconnection detection signal is input, the EEFROM 27
The alarm flag 19a' within is set to logic "O"-"1".

The operation of the liquid crystal printer 1 having the above configuration will be described below.

The main power of the liquid crystal printer 1 is turned on to perform a printing operation. By this operation, power is supplied to the main controller 22 and the print head controller 23, and the liquid crystal printer 1 starts its initial operation according to the flowchart shown in FIG.

First, the CPU 26 performs initial setting operations such as connecting the CPU 26 and the ROM 24 and controlling power supply to each part (
Step 5T1). Next, according to the system program in the ROM 24, the alarm flag 14' in the EEPROM 27 mentioned above is read.

17a', 17b', 18a', 18b'.

It is determined whether only one of the flags 19a' and 19b' is set to "1" (step 5T).
2). Here, alarm flags 14', 17a', 17
b', 18a', 18b'.

If "1" is not set in either of 19a' and 19b', heaters 17b, 18b, 19b and motor 14
Set "1" to the safety flag 38' provided in the RAM 25 to permit the operation of the
), then the process moves to execution of main processing for image forming operation (step 5T6). Here, the safety flag 38' in the RAM 25 means that when an abnormality is confirmed in the device by the self-diagnosis function, it forces the energization of the loads that would be dangerous if activated, such as the heaters 17b, 18b, 19b and the motor 14. This flag is used to prohibit each heater 17b during the main processing (step 5T6).

18b, 19b and the motor 14. When executing this operation, the safety flag 38' is checked, and if the safety flag 38' is not set to '1', the above-mentioned loads are controlled not to be energized.

That is, in the process of step ST2, after the main power is turned on and initial settings are made, the CPU 26 immediately performs the EE
Alarm flags 14', 17a', 1 in PROM27
Check the status of 7b', 18a', 18b', 19a', and 19b'. If all of these flags are not set to "1", the alarm flag state of the EPROM 27 when the main power was turned off before the main power was turned on may cause any problems for printing. What was not included is that the motor rotation abnormality did not occur when the main power was turned off last time, and each thermistor 17a, 1
8a, 19a, and each of the heaters 17b, 118b, and 19b were also shown to be in a state where they were not disconnected. Therefore, R
The safety flag 38' of AM25 is set to 1'' (step 5T5), and then the main processing is executed (step 5).
Perform T6).

On the other hand, on the other hand, the alarm flags 14' and 1 of the EPROM 27
7a', 17b', 18a', 18b'.

If either one of the flags 19a' and 19b' is 1'' (Y in step ST2), it is determined whether the dip switch 30 is turned on (step 5T3). ,1
When the disconnection repairs of 8a and 19a and the repair of the motor 14 are completed, and the cause of the failure that activates the self-diagnosis function is removed,
This is done by a repairman. Therefore, dip switch 3
If 0 is on, the alarm flag indicating that the thermistor 17a, 183, 193, etc. written in the IF and EPROM 27 is disconnected is cleared (10'') (step 5T4), and the above-mentioned safety flag 38'
(Step 5T5). However, if the dip switch 30 remains off, the thermistor 17a.

Since the repair of the disconnection of wires 18a and 19a has not been completed, the safety flag 38' is not set (step 5T5) and the process proceeds to the main process (step 5T6).

In the initial operation of the main process (step 5T6), the fluorescent lamp 17, liquid crystal shutter 18, and fixing device 12 are set at the set temperature! 3
(ready state), the heaters 17b and 18 of each part
19b, the worm amplifier operation is performed, and the initial rotation operation of the motor 14 is also performed. At this time,
No alarm flag is set in the EEPROM 27, and the safety flag 3 is set in step ST5 as described above.
8' is set and the main process (step 5T6) is executed as a normal operation, the heater 17b.

18b, 19. In this state, the self-diagnosis subroutine program shown in FIGS. 4(a), 4(b), and 4(c) is executed to detect abnormal conditions in each part.

FIG. 4(a) shows the fluorescent lamp 17. 4 (b) is a process for detecting the rotation of the motor 14; FIG. (C) is a fluorescent lamp 17. Heaters 17b and 1 attached to the liquid crystal shank 18 and the user roll 19 (fixing device 12)
This is a warm-up completion detection process that detects disconnection of wires 8b and 19b and detects the preparation completion state of each part.

Detection of disconnection of the thermistors 17a, ) 8a, 19a is processed according to the flowchart shown in FIG.
l). Next, if the thermistor 17a is disconnected, the disconnection detection circuit sends a disconnection detection signal to the main controller 22, and the alarm flag 17a' in the EEFROM 27 is set from 0'' to 1 (step U2). Return to the process (step 5T6). Also, the thermistor 17
If the thermistor 17b is not disconnected, then it is determined whether the thermistor 17b is disconnected (step U3). The disconnection of the thermistor 18a is detected by determining whether the thermistor 18a is disconnected by the aforementioned disconnection detection circuit in the print head controller 23, and if the thermistor 18a is disconnected, the disconnection detection circuit sends the disconnection detection circuit to the main controller 22. Sends a signal and sets alarm flag 18a' in EEPROM 27.
is set from "Q' to "1" (step U4).

Then, the process returns to the main process (step 5T6).

Furthermore, if the thermistor 18a is not disconnected, then it is determined whether the thermistor 19b is disconnected (step U5). The disconnection of the thermistor 19a is detected by determining whether the thermistor 19a is disconnected by the aforementioned disconnection detection circuit in the fixing temperature control unit 35, and if the thermistor 19a is disconnected, the disconnection detection circuit sends the disconnection detection circuit to the main controller 22. Sends a signal, E] Alarm flag 19 in EFROM 27
Set a' from "O" to "1" (step U6). Then, the process returns to the main process (step 5T6).

FIG. 4(b) shows the rotation detection process of the motor 14.

First, the CPU 26 determines whether a rotation-on signal for rotating the motor 14 is output (Step 1). If the rotation-on signal is not output, the CPU 26 detects the morph non-rotation (hereinafter referred to as motor lock) detection in the RAM 25. Clear the counter (step V3). On the other hand, if the rotation-on signal is output, it is determined whether the motor 14 is actually rotating (step V2). The rotation of the motor 14 is detected by the encoder 14 attached to the motor 14 as described above.
By detecting the signal from a, the rotation detection circuit in the motor controller 34 detects the rotation of the motor 1.
If the motor 4 is rotating, the counter in the RAM 25 is cleared as described above, but if the motor 14 is not rotating, a +1 signal is sent to the RAM 25 at a predetermined period, and when this counter reaches a predetermined value ( When counting up),
The alarm flag 14' indicating the motor lock state in the EEFROM 27 is set to "0" - "1" (step
V6). The reason why the counter is provided to delay the detection time is that there is a time delay between the sending of the rotation-on signal of the motor 14 and the time when the rotation detecting circuit detects this. If the motor is not rotating normally, the rotation detection circuit will not output a signal before the counter counts up and the counter cannot be reset, so the alarm flag 14' is set to "1".

FIG. 4(C) shows disconnection detection processing for the heaters 17b, 18b, and 19b. First, the CPU 26 determines whether the warm-up has been completed by checking whether the warm-up completion flag "O" in the RAM 25 is "1" (step Wl). At this time, if the warm-up completion flag of the RAM 25 is "1", the main processing continues as is, but if the warm-up is not completed, a timer that starts at the same time as the main power is turned on is activated for a preset time (this time). All heaters 17b and 18b are included in the timer.

If the operation of 19b is normal, it is determined whether the time (slightly longer than the time from turning on the main power to reach the ready state) has been reached (step W2), but this judgment immediately after turning on the main power turns out to be no. Thereafter, judgment is made as to whether the fluorescent lamp 17 has reached a predetermined temperature (completion of warm-up) (step W3), judgment as to whether the liquid crystal shutter 18 has reached a predetermined temperature (completion of warm-up) (step W5), It is determined whether the user roll 19 (thermal fixing device 12) has reached a predetermined temperature (warm-up completion) (step W7), and when each warm-up is completed, the corresponding R
Ready flag 17' in AM25.

18' and 12' are changed from "0" to "1" (Stella 7'W
4. W6. W8). And all the lady flags 17'
, 18', 12' are 1", and if they are 1", the warm-up completion flag 39' is set to 0"-"1".
(Step W9°Wlo). Furthermore, the above-mentioned timer is cleared (step W11).

On the other hand, in determining whether the timer has timed up (step W2), if the timer has timed up, at that point the fluorescent lamp 17. The liquid crystal shutter 18 and the heat fixing device 12 are heated to a predetermined temperature and the corresponding ready flags 17' and 18'
, 12' are 1'' (step Wl 2.
Wl 3).

The fact that any of the ready flags 17', 18', 12' is not l'' at the time the timer times up means that the corresponding heater 17b, 18b.

19b is broken. That is, the time-up time of the timer is determined by each heater 17b, 1 as described above.
If 8b and 19b are normal, the time is set to be enough to heat the fluorescent lamp 17, etc. to a predetermined temperature, but even if the timer times up, the fluorescent lamp 17, etc. does not reach the predetermined temperature. The corresponding heater 17b, 1
8b.

19b is determined to be disconnected.

Then, the heater 17b is activated according to the above determination result.

Alarm flags 17b', 18b', 19b' in the EEPROM 27 corresponding to 18b, 19b are changed from 0" to "1"
(Steps W14.W15°Wl6).

The alarm flags 14' and 17a' in the EEFROM 27 are set by the self-diagnosis process as described above.

17b', 18a', 18b', 19a'.

If even one of the bits 19b' is set to 1'', the same process as shown in FIG. 4(d) is performed during the execution of the main process (step 5T6).
, (e), the operation of the device is stopped and the detected abnormal state is displayed.

That is, as shown in FIG. dl, the alarm flags 14', 17a', and 17b' in the EEPROM 27.

If 1" is set in 18a', 18b', 19a', and 19b' (step Sl is Y), the display unit 37 performs an abnormal state display process by sounding or emitting light (step S2), and takes appropriate action. Thermistor 17a, 18a, 1
9a or the heaters 17b, 18b, 19b or the motor 14 is not rotating abnormally. At the same time, as shown in FIG.

If "1" is set in 18b', 19a', 19b' (step T1 is Y), the operation stop signal is sent to the CPU 2.
6, and the printing operation is stopped (step T2).

During main processing, EEPRO is set at step S1 and TI.
If the alarm flag M27 is not detected, normal display operation (step S3) and print operation (step T3) are performed.
and the main process is Il! Continue execution.

On the other hand, when the power is turned on, an alarm flag is written in the EEPROM 27, step ST5 is not executed as described above, and the safety flag 38' is "0".
When the initial operation of the main process (step 5T6) is executed, each heater 17b.

18b, 19b and the motor 14 are not energized, and therefore neither warm-up nor initial rotation of the motor is performed, and even if the main power is turned on and off repeatedly, there will be no meaningless heating or heating operation. No motor drive operation occurs.

Since the alarm flag has already been set in the EEPROM 27, the abnormality display and stop processing shown in Figure 4(d), +8) is immediately executed, so the device does not operate at all and the abnormality display is performed. Only.

As mentioned above, abnormality detection data (self-diagnosis results) of thermistors, heaters, motors, etc. are stored in the non-volatile EEFROM27.
By writing and holding each alarm flag in the EEPROM 27, even if the main power is subsequently turned off, the above-mentioned data will be reliably held in the EEPROM 27 until the power is turned on again. Therefore, if you turn on the main power again and perform the print operation again according to the flowchart in Figure 3,
The data in the EEPROM 27 is simply judged in step ST2, and the fourth
The abnormality display and stop processing shown in Figure (d) and (() can be performed immediately.

In addition, when the repair of the defective state detected by the above-mentioned self-diagnosis IJtf+ function is completed, the repairman will
If you turn on the power with 0 on, EEFROM27
All alarm flags within are cleared (step 5T
4) Normal printing operations can be performed.

In this printing operation, a uniform charge is applied in advance to the circumferential surface of the photoreceptor drum 2 by the charger 3, and as described above, the light from the fluorescent lamp 17 that reaches a predetermined temperature and is maintained at that temperature is emitted. Similarly, when a predetermined temperature is reached, exposure containing image information is performed on the circumferential surface of the photoreceptor drum 20 via the liquid crystal shutter 18 which is maintained at that temperature to form an electrostatic latent image. and,
Furthermore, the electrostatic latent image is visualized by the developing device 5, and the g image (toner image) is transferred to the paper P via the transfer device 6, and the paper 11! Thermal fixing is performed by a thermal fixing device 12 located on the feeding path 8.

At this time, the user roller 19 in the heat fixing device 12 is also heated and maintained at a predetermined temperature, so that efficient heat fixing is performed and the paper is fixed.
It forms a good image.

As described above, in this embodiment, the contents of the self-diagnosis results are stored in the EEFROM 27 using the EEFROM 27, and the contents are retained even when the main power is turned off.
No matter how many times the main power is turned on and off, the contents of the self-diagnosis results in the EEFROM 27 are retained, and the problems shown in the conventional example are solved.

In this embodiment, the EEFROM 27 is used as a non-volatile and writable storage means, but it is needless to say that it is not limited to the EEFROM 27.

In addition, in this embodiment, a liquid crystal printer 1 is used as an image forming apparatus.
Of course, the present invention is not limited to liquid crystal printers.

〔Effect of the invention〕

As explained in detail above, according to the present invention, the self-diagnosis results can be retained even when the power is turned off, so that the retained self-diagnosis results can be displayed immediately when the power is turned on again, so that the self-diagnosis results can be displayed even when the power is turned on again. Even if it is turned off, the condition of the device will not deteriorate because of this.

Furthermore, since no battery is used, there is no risk of losing self-diagnosis results due to a dead battery.

Furthermore, since it can be carried out simply by using an EEFROM, the self-diagnosis results can be held inexpensively and reliably.

[Brief explanation of the drawing]

Fig. 1 is a control circuit diagram of the liquid crystal printer of this embodiment, Fig. 2 is a schematic configuration diagram of the liquid crystal printer of this embodiment, Fig. 3 is an overall flowchart of the liquid crystal printer of this embodiment, and Fig. 4 (a) is a flowchart for detecting disconnection of the thermistor, FIG. 4(b) is a flowchart for detecting rotation of the motor, FIG. 4(C) is a flowchart for detecting disconnection of the heater,
FIG. 4(d) is a flowchart of the display processing of the display unit, and FIG. 4(e) is a flowchart of the operation processing of the liquid crystal printer. DESCRIPTION OF SYMBOLS 1... Liquid crystal printer, 2... Photosensitive drum, 4... Print head, 12... Fixing device, 14... Motor, 14a... Encoder, 17... Fluorescent lamp, 17a, 18a, 19a... thermistor, 18...
LCD shutter, 19...Hiuser roll, 26...CPU. 27 - EEPROM. 30...Dip switch, 34...Motor controller, 35...Fusing temperature control unit. Patent applicant Casio Electronics Industries Co., Ltd. Same as above
Casio Computer Co., Ltd. Figure 3 (a) Figure 4

Claims (1)

[Scope of Claims] An image forming apparatus having a self-diagnosis function that detects an image formation impossible state inside the apparatus and prohibits image forming operation based on the detection result, the image forming apparatus storing the detection result of the image formation impossible state inside the apparatus. 1. An image forming apparatus comprising: a writable and erasable nonvolatile storage means, and a determination means for determining whether to start an image forming operation at power-on according to data stored in the storage means.