JP3123347B2 - Equipment abnormality detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting an abnormality in a device such as a printer, a copying machine, a facsimile or the like using a microcomputer as a control circuit.

[0002]

2. Description of the Related Art Conventionally, in this kind of electronic equipment, a CPU, which is a core of a control circuit, performs various processing operations based on a predetermined program, but may run away due to external noise or the like. . As a countermeasure against runaway of the CPU, a watchdog timer is generally used.
This watchdog timer is reset by a reset pulse output from the CPU at a predetermined cycle when the CPU is operating normally, and the reset pulse is not output from the CPU when the CPU becomes abnormal. The timer times out and resets the CPU. As a result, the CPU performs a reset operation, that is, an initialization operation in the same manner as when the power is turned on. In the initialization operation, for example, in the case of a laser printer, a scanner motor is driven to check whether the number of rotations has reached a normal speed, a laser diode is emitted to detect a beam, and the fixing device reaches a predetermined temperature. It is an operation to check whether or not it has been done. It is conceivable that the reset operation is repeated under the influence of external noise at the time of the laser emission or the like.

[0003]

However, as described above, when noise occurs frequently due to any failure, C
Due to the runaway of the PU, the watchdog timer repeatedly times out and repeats the initialization operation. A possible cause of the time-out of the watchdog timer is, for example, that a ground contact failure occurs at the screwed portion due to vibration of the device or the like, and electrical noise is likely to occur. In such a case, in particular, in the case of a high-voltage ground, a discharge may occur to the photosensitive drum used for the image recording process, and the photosensitive drum is destroyed. Therefore, when the initialization operation is repeated as described above, when a high voltage is applied during the initialization, the discharge to the photosensitive drum is repeated, and the photosensitive drum is repeatedly destroyed, thereby increasing machine damage. There was a problem. SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem . When a watchdog timer times out due to runaway of a CPU , a high voltage is applied.
Whether initialization operation processing is disabled depending on whether
An object of the present invention is to provide a device abnormality detection device that can prevent damage to component parts of a device by determining whether or not the component is defective.

[0004]

In order to achieve the above object, an apparatus abnormality detecting apparatus according to the first aspect of the present invention is provided with a predetermined professional
A CPU for controlling each part of the device according to the
When the PU is operating normally, a certain period
Reset timer by reset pulse output at
When the CPU is not normal, the reset pulse is output.
If the CPU is not activated and the timer times out,
Error detection of equipment equipped with initialization means for reset operation
In the output device, the device applies a high voltage to a required portion of the device.
A high voltage applying unit for applying the voltage, wherein the CPU comprises:
When the high voltage is not being applied by the high voltage applying means.
If the timer of the initialization means times out,
The CPU performs a reset operation, and the timer is triggered while a high voltage is being applied.
When timeout occurs, apply high voltage as error processing.
It includes operation control means for stopping .

[0005]

According to the apparatus for detecting abnormality of a device according to the first aspect of the present invention, when the CPU is operating normally, the C signal is detected.
The timer of the initialization means is reset by a reset pulse output from the PU at a constant cycle. When the CPU is not normal, the reset pulse is not output, and when the timer times out, the CPU is reset.
If the timer times out other than during high voltage application,
The CPU is reset and the timer is started while the high voltage is being applied.
When timeout occurs, high voltage cannot be applied as an error.
Noh.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a laser printer to which an abnormality detecting device according to the present invention is applied will be described with reference to the drawings. FIG. 1 is a schematic sectional side view of the laser printer 1. The laser printer 1
A recording process unit 3, a fixing unit 4, a laser scanner unit 5, and the like are built in the main body case 2,
A paper cassette 6 is detachably set on the upper surface of the main body case 2. A paper discharge tray 7 is set on the front of the main body case 2. The recording process unit 3 includes a photosensitive drum 8, a transfer roller 9, a developing roller 17, and a charger 10 for charging the photosensitive drum 8 facing the photosensitive drum 8. Further, the fixing unit 4
Has a heating roller 11 and a pressing roller 12, and the laser scanner unit 5 has a laser emitting unit 30, a scanner motor 13, a lens 14, and a reflecting mirror 15.

Further, a developing device 16 is provided adjacent to the recording process unit 3, and a developing roller 17 is disposed in the developing device 16 so as to face the photosensitive drum 8.
A toner cartridge 18 containing toner to be supplied to the developing roller 17 is mounted. A paper feed roller 19, a separation pad 20, a pair of transport rollers 21, a pair of paper discharge rollers 22, and the like are provided along a transport path of the paper P carried out from the paper feed cassette 6. Further, a power supply unit 23, a control circuit board 24, a laser drive circuit board 25, and the like are provided in the main body case 2. With one drive motor 31 (see FIG. 2), the feed roller 19 and the transport roller 21
And the like, and an operation of driving the image forming unit such as the photosensitive drum 8 is performed.

Next, a printing operation by the laser printer 1 having the above configuration will be described. The paper P is carried out of the paper supply cassette 6 by a paper supply roller 19, and is carried in by a conveyance roller 21 between the photosensitive drum 8 and the transfer roller 9.
On the other hand, the laser scanner unit 5 is connected to a personal computer (not shown) from an interface 32 (see FIG. 2).
A laser beam is applied to the photosensitive drum 8 based on the image data transmitted through the CPU 10 to form a latent image on the photosensitive drum 8. This latent image is developed into a toner image by the developing device 16 and transferred onto the paper P by the transfer roller 9. The image transferred onto the sheet P is fixed by the fixing unit 4, and the sheet P is discharged to the discharge tray 7 by the discharge rollers 22. In the laser printer 1, at the time of continuous printing, a plurality of sheets of paper P are continuously carried out one by one from the paper supply cassette 6, are formed as described above, and are sequentially discharged to the paper discharge tray.

Next, the control section of the laser printer 1 will be described with reference to FIG. The control unit performs a logical operation according to a predetermined program to control each unit of the printer.
33, a ROM 34 storing various programs executed by the CPU 33, and an R storing various data and the like.
An AM 35, an EEPROM 36 for storing whether or not a static elimination operation is performed when the power is turned off;
And a watchdog timer 37 that resets (initializes) the CPU 33 by interrupt processing when an abnormality in the operation of the CPU 33 is detected. In addition, the CPU 33
The ROM 34, the RAM 35, the EEPROM 36, and the watch dog timer 37 are connected, and the drive motor 31, the charger 10, the laser light emitting unit 30, and the developing roller 17 are connected via the respective drive circuits 38 to 41. . Further, the CPU 33 includes an interface 32 for receiving data from an external device such as a personal computer (not shown).
Is connected. The drive motor 31 is connected to the feed roller 19 and the transport roller 2 via a transmission mechanism (not shown).
1. The photosensitive drum 8, the heating roller 11, the paper discharge roller 22, and the like are rotationally driven.

The CPU 33, ROM 34, R
AM35, EEPROM36, watchdog timer 3
7 and each of the drive circuits 38 to 41 are connected to the control circuit board 24.
It is provided in. The watchdog timer 37 has a CP
When the U33 is operating normally, the watchdog timer 37 is reset by a reset pulse output from the CPU 33 at a constant cycle. However, when the CPU 33 runs out of control and stops operating normally, a reset pulse is output. The watchdog timer 37 times out. At this time, the CPU 33 performs a reset operation. Note that the drive circuits 39 and 40 constitute a high voltage application unit of the present invention.

The timeout output of the watchdog timer 37 is output from a non-maskable interrupt (NM
I) to the terminal, whereby the CPU 33 executes the reset program in the interrupt processing. Also, CP
U33 counts the number of reset operations due to the timeout of the watchdog timer 37, and
When the count reaches a predetermined number (for example, two or more), the reset operation is stopped and the printer is disabled. I have. That is, the CPU 33 or RA
M35 and the like constitute the counting means and the operation control means of the present invention.

Next, a non-maskable interrupt (NMI) process in the laser printer 1 configured as described above will be described with reference to FIG. First, when the watchdog timer 37 times out and enters non-maskable interrupt processing, first, the number of non-maskable interrupts N
(N immediately after turning on the power is zero) is added by +1 (S1), and it is checked whether or not the number N is 1 (S2). If the number N is 1 (YES in S2), the CPU 33 performs a reset process. (S3) to end the NMI process and return to the main routine.

The number N of non-maskable interrupts is 1
If not, that is, 2 or more (N in S2
O) Since the interrupt process is two or more times, the print process is disabled (S4), the NMI process ends, and the process returns to the main routine. Instead of the method of disabling the printing process by the number N of non-maskable interrupts to the CPU 33, the printing operation may be disabled when the reset process (operation) of the CPU 33 recurs within a predetermined time. Automatically limiting excessive reset operation in this manner is particularly useful in a device such as a facsimile device in which power is turned on and no person is near the device, and in the case of a facsimile device. Is convenient for the transmission partner.

Next, a main processing routine of the laser printer 1 thus configured will be described with reference to FIGS. When the power is turned on, first, an initialization process is executed (S10). The static elimination process shown in FIG. 5 is a part of the initialization process. First, it is determined whether or not it is necessary to neutralize the photosensitive drum 8 based on the data in the EEPROM 36. Normally, the charge is removed by rotating the photosensitive drum 8 immediately after the printing operation. However, when the power is turned off before the charge removal operation, the charge removal operation cannot be performed. Since it is necessary to perform the static elimination operation when the power is turned on, it is stored in the EEPROM 36 whether or not the static elimination operation is necessary before the printing operation when the power is turned on again, and it is determined based on this information. When the charge removal operation is required (YES in S11), the charger 10
And a high voltage (for example, 5 KV)
And 600 V) (S12), and simultaneously rotates the photosensitive drum 8 (S13). Then, after an arbitrary period of time, for example, two seconds, the lens 14 and the reflecting mirror 1
5 irradiates the photosensitive drum 8 with a laser beam (S
14).

Next, after a predetermined time, for example, one second, the application of the high voltage to the charger 10 and the developing roller 17 is sequentially stopped (S15). After three seconds (the time required for one rotation of the photosensitive drum 8), the irradiation of the laser beam to the photosensitive drum 8 is stopped (S16), and the rotation of the photosensitive drum 8 is stopped (S17). The charge elimination process after the re-input is completed, the NMI process and other initialization processes in the laser printer are performed, and the process returns to the main routine. On the other hand, when the static elimination operation is not necessary (N11 in S11)
O) Immediately ends the static elimination process and initializes the RAM 35
Other initialization processing in the laser printer such as NMI processing is performed, and the process returns to the main routine.

When the initialization process is completed (S1)
0), it is determined whether or not print processing is possible (S20). If print processing is possible (YES in S20), a ready output is output to an external device (S30), and a print start signal is sent from the external device. It is determined whether or not it has been received (S40). When a print start signal is sent (YES in S40), print processing is performed based on the sent print data (S5).
0). When the printing process is completed, the above-described S3
Return to 0. Further, when the printing process is disabled in the NMI process or when the toner remaining amount is detected by the toner remaining amount detecting process of the initialization process, it is determined that the printing process is not possible (NO in S20), and the state is determined. Wait until resolved.

In the above embodiment, whether or not the printing process is disabled is determined in accordance with the count of the reset operation of the CPU 33 by the counting means. However, when the watchdog timer 37 times out, Whether or not to disable the printing process may be determined based on whether or not a high voltage is being applied. That is, FIG. 6 shows a processing procedure in this case. In FIG. 6, when the watchdog timer 37 enters a non-maskable interrupt processing (NMI processing) due to a time-out, first, during application of a high voltage, that is, the charging device 10 and the developing roller 17 It is determined whether or not a high voltage is applied to each of them (S61). If the high voltage is not being applied (NO in S61), the CPU 33 is reset (S62), the NMI process ends, and the process returns to the main routine. If a high voltage is being applied (YES in S61), it is determined that an error has occurred and the charging device 10
The application of the high voltage to the developing roller 17 and the like is stopped, the printing process is disabled (S63), the NMI process ends, and the process returns to the main routine. By performing such processing, as described in the related art, it is possible to prevent the occurrence of repeated application of a high voltage to the photosensitive drum 8 many times due to some abnormality, thereby preventing the photosensitive drum from being destroyed. Can be.

It should be noted that the present invention is not limited to the above embodiment, and various modifications are possible. For example, a CP without an NMI terminal
In the case of U, a normal interrupt terminal may be used,
Also, the number of initializations is counted by hardware and the CPU
Can be controlled by using the reset terminal.

[0019]

As described above, according to the apparatus abnormality detecting apparatus of the first aspect , the interrupt processing is performed when the timer times out due to the runaway of the CPU.
If the timer times out other than during application, the CPU
Performs reset operation, but timer runs while high voltage is applied.
If it goes out, it is considered as an error that high voltage cannot be applied.
Therefore, the necessary reset operation is performed as usual,
It is possible to avoid a situation in which the pressure load is destroyed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a printer showing an example of a device in which an abnormality detection device of the present invention is implemented.

FIG. 2 is a block diagram of an abnormality detection device.

FIG. 3 is a flowchart of an interrupt process when an abnormality is detected.

FIG. 4 is a flowchart of a main process of the printer.

FIG. 5 is a flowchart of an initialization process.

FIG. 6 is a flowchart showing a process when a watchdog timer times out.

[Explanation of symbols]

 Reference Signs List 10 charger 17 developing roller 33 CPU 36 EEPROM 37 watchdog timer 39 drive circuit 41 drive circuit

Continuation of the front page (58) Fields investigated (Int.Cl. ⁷ , DB name) G06F 11/14 G06F 11/00 G03G 15 / 00,21 / 00 B41J 29/00-29/70

Claims (1)

(57) [Claims] 1. Each part of the device is controlled according to a predetermined program.
The controlling CPU and if this CPU is operating normally
Reset pulse output from the CPU
Resets the timer, and if the CPU is not normal
The reset pulse is not output and the timer
Initialization procedure to reset the CPU when it
And a step for detecting an abnormality of the device, the device comprising a step for applying a high voltage to a required portion of the device.
A voltage application unit, wherein the CPU is applying a high voltage by the high voltage application unit.
The timer of the initialization means has timed out
Resets the CPU and applies high voltage.
If the timer times out at
A device for detecting abnormality of a device, comprising an operation control means for stopping application of a high voltage .