JP2000122488A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of adequately coping with jamming occurring with AC input interruption. SOLUTION: A power source unit 10 outputs a DC voltage based on AC input. The unit 10 has a circuit 12 detecting the zerocross of the AC input. A CPU 31 is driven by the DC voltage, and detects the interruption of the AC input based on the zerocross signal. When jamming occurrence is detected based on the output of a paper sensor 37, jamming data storing is started. In the case of the AC input interruption, only when the jamming data storing is finished before the AC input interruption is detected, the jamming data are assumed to be valid by displaying a jamming data storage finish flag, and the jamming data are utilized when a power source is to be turned on again.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as an electrophotographic copying machine, and more particularly to a method for coping with an unexpected interruption of an AC input.

[0002]

2. Description of the Related Art An image forming apparatus such as a copying machine usually includes a power supply unit for transforming, rectifying, and smoothing an AC input to generate a plurality of different DC voltages. The DC voltage is, for example, a relatively low voltage VL (5 V) for driving an electric circuit including a CPU and a relatively high voltage V for driving an electromechanical device such as a clutch, a solenoid, and a motor.
H (24 V).

[0003]

Such a power supply unit, due to its structure, includes a relatively large-capacity capacitor for storing electric charge, and when the AC input is cut off for some reason, the electric charge is lost. It takes a predetermined time until the output voltages of VH and VL become 0 after discharging. For this reason, even after the AC input is cut off, the C that uses VL as the input voltage is used.
Electronic components such as a PU and an ASIC continue to operate for a while. On the other hand, a motor or the like that uses VH as an input voltage requires more power, and thus immediately stops operating when AC input is cut off.

Incidentally, in an image forming apparatus such as a copying machine, there is a case where a jam occurs in which the paper stays on the transport path. For this reason, a paper sensor is arranged at a predetermined position on the paper transport path in the apparatus, and the occurrence of a jam is detected based on the sensor output. When such a jam occurs, the copy mode settings (the selected paper size, density, magnification, etc.) at that time, the number of copies in progress up to that point when a plurality of copies are designated, and the like. Data (jam data) indicating the copy state at that time is stored, and at the time of jam recovery after paper removal, the copy operation is continued based on the stored jam data. That is, copying is executed for the remaining number of copies in the same setting state.

When an unexpected AC disconnection such as opening of the front door or disconnection of the power plug occurs during the power-on of the apparatus, especially during the copying operation, even after the conveyance of the sheet by the voltage VH is stopped, the operation is continued for a while. During this time, a state occurs in which the jam detection operation using the voltage VL continues. For this reason, a jam is detected even though the jam is not caused by a normal conveyance failure. At this time, the device attempts to save the jam data as in the case of normal jam detection. However, since the operation in this case is an operation after the power is turned off, it is not guaranteed that the operation is performed normally. As a result, when the power is turned on again after the jam recovery,
The apparatus may read the wrong jam data and continue the copy operation.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus having a new function capable of appropriately coping with a jam occurring due to such an interruption of AC input.

[0007]

According to the present invention, there is provided an image forming apparatus comprising: a power supply unit for outputting a first DC voltage obtained based on an AC input and a second DC voltage lower than the first DC voltage; A sheet conveying unit that is driven by a DC voltage, conveys a sheet to an image forming unit, and discharges the sheet after forming an image, and operates at the second DC voltage to detect the presence or absence of a sheet on a sheet conveying path. A paper sensor and the second
A jam detection unit that operates with the DC voltage of the second and detects a jam based on the output of the paper sensor; an AC input disconnection detection unit that operates with the second DC voltage and detects the interruption of the AC input; Operates at a DC voltage of the predetermined value, and when the occurrence of a jam is detected by the jam detection means, starts storing predetermined data. When the data storage is completed, a data storage completion flag indicating that the data storage is completed. And control means for continuing the image forming operation based on the contents of the data when the data storage completion flag is set when the power is turned on again after the recovery from the jam.

The "predetermined data" is state data at that time, such as the contents of the operation mode and the number of intermediate images formed.

The jam detecting means and the control means are a CPU
Can be realized by the program processing. By setting a data storage completion flag and storing only when the predetermined data has been stored when a jam occurrence is detected,
The validity of the data can be determined. Therefore, when the power is turned on again after the recovery from the jam, the data can be used only when the data storage completion flag is set, and copy continuation from an erroneous state is avoided.

[0010] The data storage completion flag may be set not only when the data storage is completed but also when no AC input disconnection is detected at that time. In this case, if a jam occurs due to the interruption of the AC input, the jam data saving completion flag is not set even if the jam data saving is completed. As a result, the state can be unified when a jam occurs due to the interruption of the AC input, and the state can be initialized after the jam is recovered.

More specifically, the AC input disconnection detecting means includes: a zero cross signal generating means for detecting a zero cross of the AC input to generate a zero cross signal; a means for periodically counting the zero cross signal; Means for measuring the time from when the count value of the zero-cross signal is cleared to zero based on a clock; and the measured time becomes larger than a predetermined value before the count value of the zero-cross signal reaches a predetermined value. Means for judging the fact.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a block diagram of control hardware of a copying machine as an image forming apparatus to which the present invention is applied.

In FIG. 1, a power supply unit 10 for generating two output voltages of 24 V and 5 V, which are first and second DC voltages, from an AC input, and an operating voltage of 24 V and 5 V from the power supply unit 10. And a control unit 30 for controlling a heater drive circuit and the like (not shown), a sheet conveying unit 22 for conveying a sheet, and an operation unit 40 for providing an interface between the control unit 30 and a user. Although not shown, the operation unit 40 includes various operation keys and a display unit.

As is well known, the power supply unit 10 transforms, rectifies, and smoothes an AC input to generate DC voltages of 24 V and 5 V. The voltage output circuit has a relatively large-capacity capacitor 11. In the present embodiment,
The power supply unit 10 has a zero cross signal generation circuit 12 that detects a zero cross of the AC input voltage and generates a zero cross signal (pulse signal). This zero cross signal is used as an interrupt signal of the CPU 31 described later.

The control unit 30 includes a CPU 31 for controlling the entire operation of the copying machine (image exposure, development, fixing, sheet feeding, etc.), a memory 32 for storing an operation program of the CPU 31 and various data, and a periodic interruption. Has a timer 34 for generating Further, in the memory 32, C
Zero cross counter 321, timer counter 322, power supply OF updated by program control by PU31
F flag 323, jam data storage completion flag 324,
Each memory area of the jam data storage area 325 is provided. At least, the jam data storage area 325 stores data in a nonvolatile manner. The specific function of each of these memory areas will be described later.

In this embodiment, the CPU 31 and the memory 3
2. Electronic components such as the timer 34 operate at 5V, and the paper transport unit 22 including the motor operates at 24V.

Hereinafter, the operation of the present embodiment will be described.

First, when the power of the copying machine is turned on, FIG.
In the power-on processing described later, an initialization processing is executed (S51). Specifically, the CPU 31 starts zero-cross monitoring. That is, the timer 34 is reset, and the count of the zero-cross counter 321 and the count of the timer counter 322 are cleared to zero.
Further, the count of the number of times of zero crossing is started by permitting the zero cross interrupt by the zero cross signal, and the time measurement of the timer 34 is started by permitting the timer interrupt.

FIG. 2 shows a processing flow of a timer interrupt executed by the CPU 31 when the timer 34 interrupts the CPU 31.

In this embodiment, the timer 34 is set to 2 ms
A timer interrupt is generated for the CPU 31 every ec. Each time this timer interrupt occurs, the CPU 31 executes the timer interrupt process of FIG. That is, first, the timer counter 322 is incremented (+1 increment) (S1).
1). Next, this count value is equal to a predetermined value P (for example, “1”).
00 ") is checked (S12). If it is less than P, this process is terminated, and if it is more than P, the power-off flag 323 is set to" 1 "(S13). As described above, in a normal state where the power is on, the count value is cleared to zero before reaching the predetermined value P.

On the other hand, a zero-cross signal is also used as an interrupt signal to the CPU 31. In a normal state, this zero-cross interrupt occurs every 10 msec when the frequency of the AC input is 50 Hz, and every 8.3 msec when the frequency of the AC input is 60 Hz. FIG. 3 shows a process flow of a zero-cross input interrupt executed in response to an interrupt performed on the CPU 31 each time a zero-cross signal pulse is generated from the zero-cross signal generation circuit 12 of FIG.

In the process of FIG. 3, the CPU 31 first increments the zero-cross counter 321 (S31).
21), the value of which is a predetermined value N (here, “10”)
It is checked whether or not it has reached (S22). If the count value has not reached N, this zero-cross interrupt processing is terminated, and if it has reached, the processing of step S23 is performed. That is, both the timer counter 322 and the zero-cross counter 321 are cleared to zero, and the counting of the zero-cross signal and the time measurement by the timer are started again (S2).
3).

If the processing of FIGS. 2 and 3 is considered in combination, the zero-cross counter stops incrementing immediately upon the interruption of the AC input, so that the timer counter is not cleared (S23 in FIG. 3). Since the timer interrupt (FIG. 2) continues, the value of the timer counter exceeds P (FIG. 2, S12). In this way, the power OFF (AC input disconnection) is detected.

Next, FIG. 4 shows a flow example of a jam detection process for detecting the occurrence of a jam in the present embodiment.

First, at the start of the copy operation, time counting is started (S41). That is, 1 m as t = 0
t is incremented every second. Therefore, it waits until the time t exceeds the predetermined time Ta (S42). Here, Ta is represented by the following equation.

Ta = estimated sheet arrival time of paper + jam allowance time When the time t exceeds Ta, it is checked whether or not the paper sensor 37 detects the presence of paper (S43). If the presence of a sheet is not detected at this time, there is a high possibility that the sheet stays upstream of the sheet sensor 37 for some reason, and it is determined that a jam has occurred.

If the sheet is detected by the sheet sensor 37 in step S43, the process waits until the time t exceeds a predetermined time Tb (S44). Here, Tb is represented by the following equation. Tb = estimated time of paper passage through sensor + jam allowance time When the time t exceeds Tb, it is checked again whether or not the paper sensor 37 detects the presence of paper (S45). At this point, the paper should have already passed through the paper sensor 37. If the presence of the paper is still detected, there is a high possibility that the paper remains at the position of the paper sensor 37 for some reason, and a paper jam occurs. Is determined.

In this manner, occurrence of paper jam in the apparatus is detected. If the paper sensors are installed at a plurality of locations on the paper transport path, the above-described processing is performed for each of the different Ta and Tb.

FIG. 5 shows an example of the flow of a jam occurrence process performed when the occurrence of a jam is detected.

First, a jam data storage completion flag (JF
LG) (324 in FIG. 1) is initialized to “0” (S3
1) Then, the storage of the jam data as described above is started (S32).

Thereafter, it is confirmed whether the storage of the jam data is completed (S33). When the power-off is detected before the completion of the jam data storage (S33, No) (S3
6, Yes), this process ends with JFLG remaining at “0”. Power OFF is the power OFF flag 3 described above.
23 can be determined.

When the jam data saving is completed (S3
(3, Yes) also checks whether the power is off (S
34). If the power is off, this process ends with JFLG set to “0”. Unless the power is off, J
The FLG is set to "1" (S35), and this processing ends.
That is, only when the jam data storage completion flag JFLG is set to “1” in step S35, it is guaranteed that the jam data has been effectively stored.

The JFLG is referred to when the power is turned on again next time. FIG. 6 shows an example of a processing flow when the power is turned on. In addition, even when the jam detected in the jam detection process of FIG. 4 is not caused by the interruption of the AC input, the power is temporarily turned off in order to remove the paper related to the jam.

FIG. 6 shows a modification of the jam occurrence processing of FIG. In the process of FIG. 5, even after the completion of the jam data storage is confirmed in step S33, the power supply OF
F, and if only the power is not turned off, the step S
JFLG was set up at 35. However, it is not always necessary to confirm that the power is off after step S33. Therefore, in the process of FIG. 6, step S34 is deleted, and step S35 is always executed in S33 and Yes. As a result, if the completion of saving the jam data can be confirmed even when a jam occurs due to the interruption of the AC input, the JFL
G is set, and the copy process can be continued based on the jam data later.

If the JFLG cannot be set up in step S35 due to a voltage drop after the completion of the storage of the jam data in step S33 in FIG. 6, the result is the same as the result of the processing in FIG. Absent.

In FIG. 7, first, the above-described initialization processing is performed (S51), and then the value of JFLG is checked (S5).
2). If JFLG is "1", the jam data is effectively stored, and the jam data is restored (S53).
I do. Subsequent processing is performed based on the jam data. On the other hand, if JFLG is not "1", the copy state is initialized (S54). That is, jam data is not used.

In this way, the jam data can be used only when the jam data has been effectively saved.

Although the preferred embodiment of the present invention has been described above, various modifications and changes can be made without departing from the scope of the claims. For example, the detection of the AC input disconnection is performed based on the zero-cross signal of the AC input, but any means may be used as long as the AC input disconnection can be immediately detected.

[0040]

According to the present invention, the jam data can be used when the power is turned on again only when the jam data is effectively saved. Therefore, even when the jam occurs due to the interruption of the AC input, the proper jam can be removed. Recovery actions can be taken.

[0041]

[Brief description of the drawings]

FIG. 1 is a block diagram of control hardware of a copying machine as an image forming apparatus to which the present invention is applied.

FIG. 2 is a flowchart illustrating a timer interrupt process according to the embodiment of the present invention.

FIG. 3 is a flowchart illustrating a zero-cross input interrupt process according to the embodiment of the present invention.

FIG. 4 is a flowchart illustrating a jam detection process according to the embodiment of the present invention.

FIG. 5 is a flowchart showing a jam occurrence process according to the embodiment of the present invention.

FIG. 6 is a flowchart showing a modification of the jam occurrence processing of FIG. 5;

FIG. 7 is a flowchart illustrating a power-on process according to the present embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Power supply unit, 11 ... Capacitor, 12 ... Zero cross signal generation circuit, 22 ... Paper conveyance part, 30 ... Control unit, 31 ... CPU, 32 ... Memory, 37 ... Paper sensor, 40 ... Operation part.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masatoshi Tanabe 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. F-term (reference) 2H027 DA03 DC03 DC14 EE08 EF01 FA40 ZA01

Claims (3)

[Claims] A power supply unit for outputting a first DC voltage obtained based on an AC input and a second DC voltage lower than the first DC voltage; and a power supply unit driven by the first DC voltage to transfer a sheet to an image forming unit. A sheet conveyance unit for conveying and discharging after image formation; a sheet sensor for operating with the second DC voltage to detect presence / absence of a sheet on a sheet conveyance path; and an operation for the second DC voltage A jam detection unit that detects a jam based on an output of the paper sensor; an AC input disconnection detection unit that operates with the second DC voltage and detects an AC input disconnection; and operates with the second DC voltage When the occurrence of a jam is detected by the jam detecting means, predetermined data is started to be stored, and when the storage of this data is completed, a data storage completion flag indicating that the data storage is completed is set and stored. When the time power is turned on again after the jam recovery standing said data storage completion flag, an image forming apparatus characterized by comprising control means for continuing the image forming operation, a based on the content of the data. 2. The image forming apparatus according to claim 1, wherein the data storage completion flag is set when the interruption of the AC input is not detected when the data storage is completed. 3. The AC input disconnection detecting means detects a zero cross of the AC input and generates a zero cross signal, a means for periodically counting the zero cross signal, and a reference clock. Means for measuring the time after the count value of the zero-cross signal is cleared to zero, and determining that the measured time has become larger than a predetermined value before the count value of the zero-cross signal reaches a predetermined value. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises: