JPS6316735B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming apparatus using a program control method.

Although an electrophotographic apparatus will be described below as an example, the present invention can also be applied to a printer that prints out data. In general, a device for automatically repeatedly obtaining electrophotographic images includes a means for making a photoreceptor rotatable, sequentially forming electrostatic latent images on the photoreceptor along the direction of rotation around the photoreceptor, and a developing means for developing the latent image. , it is necessary to arrange a means for transferring a visible image onto a copying material and a means for cleaning the photoreceptor in order to form an electrostatic latent image on the photoreceptor again, and to operate operating equipment necessary for this process at a predetermined timing. There is.

Conventionally, the load for process processing is operated by a signal from a cam switch operated by a cam corresponding to the angle (operating position) of the rotating photoreceptor, or by counting a predetermined number of pulses generated by the rotation of the photoreceptor. I was getting used to it. In this case, if you input the cam signal and pulse signal into a computer and tried to output the timing operation signal sequentially, you would have to constantly monitor the generation of the cam signal and pulse signal. Other treatments were difficult. Furthermore, in the latter case, the frequency of the clock signal for data processing within the computer is much higher than that of the pulse signal (for example, 1 μsec ^-1 ), so it is necessary to provide some kind of synchronization between the computer operation and pulse counting. It was hot. Therefore, the amount of programs and memory required for timing processing was large. Furthermore, when the copying process is performed sequentially using a computer, even if a dangerous situation such as a paper jam occurs, because the copying machine operates according to a so-called program, the dangerous situation can only be detected at a specific time. cannot be detected. Therefore, safety measures may be taken too late, resulting in inconvenience.

In order to eliminate the above drawbacks, it is possible to use a program interrupt control method, but multiple interrupt input terminals are required to perform both timing signal generation and dangerous state detection. becomes.

The present invention enables processing for both the generation of a timing signal and the detection of a dangerous condition with a single interrupt input terminal, and includes a recording medium, an actuating means for forming an image on the recording medium, a pulse a generating means, a main program for controlling the actuating means to form an image, a processing routine for forming a timing control signal, and a processing routine for detecting an abnormality in the apparatus, to be executed during interruption of the main program. a program memory (ROM) that stores an interrupt program, and an input port (IB) for interrupting execution of the main program and executing the interrupt program;
control means including address storage means (STACK) for saving the address of the main program in the program memory while the interrupt program is being executed; the pulse generation means is connected to one of the input ports of the control means; and each time a pulse is input from the pulse generation means to the one input port, the address of the main program is saved in the address storage means and the program is interrupted, and the pulse is input to the one input port. For each input, the interrupt program having both a processing routine for forming the timing control signal and a processing routine for detecting an abnormality in the device is processed, and the processing routine for forming the timing control signal and detecting an abnormality in the device are processed. The present invention is characterized in that one of the processing routines for the program is selected in accordance with the sequence and the program is processed, and after the processing is completed, the save address stored in the address storage means is read out and returned to the original main program. This is an image forming apparatus using a program control method.

This allows the determination of operation timing signals and the processing for detecting abnormalities in the equipment to be performed on a priority basis without using interrupt terminals for each process, and allows multiple different processes to be performed easily. You can quickly run them separately in different configurations.

The above objects and other objects of the present invention will be made more concrete by the following examples.

FIG. 1 is a schematic cross-sectional view of an electrophotographic apparatus that is an example of the present invention. The process system of this device and the operation of the load for process processing will be explained.

A document is placed on a document table that constitutes a document placement surface, and is pressed down by a document pressure plate 10.
01, a moving reflecting mirror 6, a lens 17, and fixed reflecting mirrors 18 and 19. Therefore, the original is moved by the movable reflecting mirror 8 which moves in the direction indicated by the arrow A in the figure together with the illumination lamp 9, and by the movable reflecting mirror which moves in the same direction at a moving speed of 1/2 of this movable reflecting mirror 8. 6, while the optical path length is kept equal, the light is further subjected to slit exposure through a lens 17 and fixed reflection mirrors 18 and 19, and is imaged onto a rotating drum 30 having a photoreceptor on its surface. That is, the document is exposed to slit light while being scanned by an optical system (illumination section). The surface of the drum 30 has a photoreceptor whose photoreceptor layer is covered with a transparent insulating layer. Becomes electrically charged. Subsequently, when reaching the exposure section 16, the original on the original platen glass is illuminated by the illumination lamp 9, and an image is formed on the drum 30 by a moving reflection mirror, a lens, and a fixed reflection mirror, so that the photoreceptor is exposed to the original image. At the same time, the AC discharger 13 is supplied with AC high voltage current from the high voltage power supply.
Get static electricity removed.

Next, an electrostatic latent image is formed on the surface of the drum (photoreceptor) by full exposure by the full surface exposure lamp 33 and enters the developing device 31 .

Development is performed by powder development using a sleeve method, and the electrostatic latent image is visualized.

The above and the following process operations are performed while the drum is rotating.

Next, the transfer material is fed from the cassette 21 or 22 by the paper feed roller 24, conveyed by the first roller 25 and second roller 28, the timing roller clutch CL is turned on, the transfer material is temporarily stopped by the roller 29, and the CL is turned on by the registration signal. Then, the roller 29 is rotated and the paper is conveyed again. The registration signal is obtained from a switch RG that detects a specific passing position of the optical system. The switch OHP generates a signal indicating the optical system home position (stop position). This fed and conveyed transfer material comes into close contact with the drum, and the image on the drum is transferred onto the copy material by a transfer charger 27 using a positive high-voltage current from a high-voltage power source. After the copying material has been transferred, it is separated from the drum by a separation roller 26, guided to a heat fixing roller 4, and after being fixed, excess charge is removed by a static eliminator 3, and the material is ejected onto a tray 20 by an ejection roller. Ru. Copying is now complete, and the remaining toner on the drum is cleaned by the blade 11 pressed against the drum surface (photoreceptor), allowing the next cycle to be repeated. The switch DHP generates a drum home position signal and stops the drum at the position where the photoreceptor joint contacts the cleaner 11. 23a, 23b
2 is a well-known pair of a lamp for detecting the presence or absence of paper in a cassette and a light-receiving element that receives the light. Pair 2 is a well-known pair of a paper detection lamp and a light-receiving element for detecting paper delay and retention. They are a pair. Reference numeral 16 is a blank exposure lamp which exposes the photoreceptor to light to eliminate surface potential unevenness when imagewise exposure is not performed.
7 is a fixing motor, 15 is an optical motor, and 14 is a pre-exposure lamp that fatigues the photoreceptor in advance to make it uniform before the process. Further, 56 is a pulse generator composed of a plate that rotates in conjunction with the drum and an optical detector (not shown) that detects light pulses generated by holes in the plate.

Figure 2 shows the operation timing of representative equipment necessary for process processing. One pulse is generated from the pulse signal generator for every 1 degree of rotation angle of the photosensitive drum.

Here, an example of generating a timing signal using a computer without an interrupt function will be described with reference to FIGS. 3 and 4.

FIG. 3 is an example of a program for connecting a clock pulse generator to a so-called input terminal of a computer and counting clock pulses on drum rotation by the computer to generate a timing signal. The execution of this program is detailed in Japanese Patent Application No. 51-36614.

FIG. 4 shows a comparison between the operating clock CP' of the computer and the clock pulse CP generated by the rotation of the photosensitive drum, with the horizontal axis being the same time axis. Step STEP1-1 in FIG. 3 is executed between the clock numbers _t1 and _t2 in FIG. 4. Third
It is assumed that the minimum instruction step for executing each step in the figure is executed with one clock pulse of clock CP'.

The number of pulses that determine the process timing by executing STEP 1-1, for example, the timing of turning on the paper feed plunger, 250 pulses, is stored in the ROM that is stored in advance.
Read from the memory and store in the memory for calculation.
At time _t2 , the process moves to STEP1-2, but since CP=0, it passes through STEP1-2 and moves to STEP1-3.
Then, between t ₂ <t < t ₃ , the process does not proceed to the next step and steps 1 to 3 are repeated.

At time t ₃ , CP=1, so move to STEP 1-4. Then, STEP1− is performed several clocks from t ₃ to t ₄ .
Execute step 4 and set the number of clocks set in memory to -
Do 1. Furthermore, execute the next STEP 1-5 from t ₄ to _{t 5} , determine whether the subtracted value is 0, and repeat STEP 1-2.
Return to And since CP=1, t ₅ ~ _{t 6}
During this time, repeat STEP 1-2. CP at t ₆
When the value becomes 0 again, the process moves to STEP 3, and STEPs 1-3 are repeated until time _t7 . Here pulse between t ₁ and t ₇
Although one CP was input, by executing STEP1-4 when CP=1, one clock pulse was counted. STEP1−
In step 5, it is determined whether a predetermined clock pulse has been counted, and steps 1-1 to 1-4 are repeated until the counting is completed. Upon completion of counting, the computer outputs an operating signal for a predetermined operating device (STEP 1-6). For example, a signal that counts 250 CP and turns on the paper feed plunger is output from a specific output terminal of the computer. In this way, the synchronization of the clock pulse CP generated in synchronization with the rotation of the photosensitive drum and the operation of the computer is performed in STEP 1-2.
This is realized by STEP 1-3. That is, the rising and falling edges of the clock pulse CP are determined and counted by one. In this case, a large number of steps for clock counting are required for timing operations depending on the number of process control loads, and these step groups are incorporated in a time series in a sequence control program as shown in FIG. Moreover, it is almost impossible to control other operating devices between counting steps.

In the present invention, the drum clock generating means is connected to the interrupt port instead of the input port, thereby counting the clocks and controlling the output. This allows other operating devices to be controlled between clocks.

FIG. 6 shows its specific circuit configuration.

In the figure, μCOM is a well-known microcomputer, as shown in FIG. 7, whose internal circuit is shown.

IA and IB are interrupt ports; IB is connected to a light receiving element _D3 that generates a drum clock signal and _C1 that shapes a waveform, and IA is connected to a trouble detection circuit that occurs within the copying machine.

D ₁ and D ₂ are display units for displaying the number of copies, DIS is a warning display unit, Tr ₁ and Tr ₂ are transistors for increasing width,
COPY is a copy start button, K is a key button from 0 to 9 for setting the number of copies, and DHP is a micro switch for detecting the drum home position. display
D ₁ and D ₂ are connected to segment selection output ports U ₀ to _{U 6} via the driver, motor M ₁ and alarm
DIS etc. are connected to output port F, DHP is connected to port S, and COPY is connected to port K. i is an inverter.

COPY key and numeric keys are turned on at the output port
Scanned by time division signals from R ₀ ~ R ₃ , K ₀ ~
Dynamically input to the input port of _K3 .
The computer reads the input signal and drives the drum motor _M1 . When the drum rotates, the disc PT rotating in conjunction with the drum motor _M1 generates an intermittent optical signal, which is detected by the light receiving element _D3 and generates a drum clock pulse. When the DHP signal is generated by the optical detection switch at the drum home position, it starts counting 250 drum clocks CP to turn on the paper feed plunger PL. That is, by inputting the DHP ON signal to the input port _S3 , reception of the drum clock to the interrupt port IB is started. When a predetermined count is reached, a drive signal is output from the output port _F1 to turn on the paper feed plunger PL, and the constantly rotating paper feed roller is lowered to feed paper. After that, turn off the PL at 50 clocks, count 100 clocks from the next DHP signal, turn on the plunger OP for driving the optical system in the same way as above, move the optical system, and start exposure at the same time. . In addition, the turning off of these devices and the operation of other operating devices that require timing are similarly controlled.

Here, a computer having an interrupt function applied to the present invention will be briefly described. This is an element diagram of a 4-bit microcomputer, μPD545 manufactured by NEC Corporation, and the functional circuit blocks in it are shown in the seventh section.
As shown in the figure.

In the figure, ROM and RAM are memory, PAG is a page register for specifying a memory group in ROM,
POLY is a step counter that specifies the memory number within the group, DP is a data pointer that specifies a register address in RAM, DP′ is a data pointer that saves that address in the event of an interrupt,
STACK is the memory that saves the ROM address in the event of an interrupt, INSTDEC is the ROM instruction word disassembly decoder, F ₀ to _{F 7} are output ports, Q ₀ to _{Q 7} are serial-to-parallel conversion registers, R ₀ to 7, U ₀ ~7 is the output port, FA is the arithmetic circuit, ACC is the accumulator,
TR is an auxiliary register, IA and IB are interrupt input ports, S ₀ to 3 are input/output ports, and K ₀ to 3 are input ports. The input/output ports and interrupt ports mentioned above correspond to each port in the circuit array shown in FIG.

The above-mentioned ROM stores in advance a program with instruction codes and the number of control clocks for sequence control of the copying process, and the RAM temporarily stores data necessary for executing process control and sets flags for discrimination. used for.

Instruction code signals are sequentially outputted from the ROM by the computer clock and are decoded by the decoder INSTDEC to generate control signals for executing the program in the ROM.

FIG. 8 is an example of a flowchart of a main program stored in a ROM for processing.

The key entry of the Kodo key will be explained using the flow shown in FIG. 8a.

First, when the power is turned on and the computer starts operating, it specifies a ROM address according to the computer clock, outputs an instruction code, and executes the program in the ROM. In step 2-1, the first bit of register Q, ie, _Q0 , is set. In step 2-2, the 8 bits of this register Q ₀ to Q ₇ are
Output to R ₀ to 7. In step 2-3, the input data to the input port K is stored in the accumulator ACC.At this time, since _R0 is output, _K0
It is determined whether the COPY button is on or not based on the input on level. When data corresponding to K ₀ to 3 is stored in ACC, the bit corresponding to K ₀ becomes 1. In the next step 2-4, the memory RAM
Data specifying the address is set in register DP, and in step 2-5, the ACC data stored in step 2-3 is transferred to address (00) of the RAM specified by that register (Figure 13). In step 2-6, it is determined whether the 0th bit of this data is 1 or not. If it is 1 (yes), the next step 2-7 is executed, and data specifying the output port _F0 is output from the ROM and stored in the register TR. In step 2-8, the output port _F0 is set, and the output of this _F0 turns on the drum drive motor via the driver. If the 0th bit is 0 in step 2-6, the flow from step 2-1 is repeated again.

Next, referring to FIG. 8B, drum clock counting by the interrupt system will be explained using an example in which the drum clock is counted 250 times and the signal PL for driving the paper feed plunger is turned on.

In step 3-0, it is determined whether the drum home signal is input to the input port _S3 . This approach follows a similar program flow as described above. 250 code is output from ROM in step 3-1.
Stored in RAM. RAM in step 3-2
The flag B in the flag register of is set (set to 1). Interrupt port in step 3-3
Set up a flip-flop to accept IB interrupts to enable interrupts by drum clock pulses. Then, in the following step 3-4, settings are made for changing the digits of the display from R ₆ and R ₇ .
Outputs the time division signal by reset, outputs the segment signal from U ₀ to _{U 6} , and outputs the segment signal from the displays D ₁ and D _2.
lights up dynamically. In this step
It has many instruction code steps from reading the ROM code to outputting from the output port. This point is well known, so I will omit the details. D ₁ , D ₂ 7
The two light-emitting segments display the set number when a key is input, and each time a copy is completed, the number is -
Display the number of 1s. The display is performed intermittently in this step. At step 3-5, the subsequent state of the flag set in step 3-2 is determined, and if it remains the same, the process waits until the flag is reset. However, if a drum clock is generated during this time, the rise of the pulse to IB resets the F/F for accepting an interrupt and inputs an interrupt. As a result, the address specified in the ROM by the program counter POLY at that time is saved in the register STACK, and another specific address (for example, 100) in the ROM is set in the counter POLY. An interrupt routine program as shown in FIG. 9 is stored starting from number 100 in the ROM, and is executed at the rise of the drum clock pulse.
Therefore, the program being executed up to that point is interrupted and a drum clock pulse counting program is executed. When the program execution is finished, the address saved in the STACK register is counted again.
Set to POLY and execute the main program from the next address.

FIG. 9 is a program of the interrupt routine. Step 4-1 subtracts -1 from the memory value 250 stored in step 3-1, and
In step 2, it is determined whether the value has reached 0 or not. Since this is the first drum clock pulse after detecting the drum home signal DHP, it is not 0, so step 4-3 is skipped and the process proceeds to the next step. In step 4-4, the interrupt acceptance F/F is set so that an interrupt is applied again when returning to the main program. If the command at step 4-5 causes the drum clock to rise immediately before step 3-4, the program returns to step 3-4 of the main program.

Operate the indicators D ₁ and D ₂ again. When the next clock pulse CP is input to port IB, F/
Since F has been set, the F/F is reset at the rise of pulse CP and the interrupt counting routine is performed again.

While doing so, 250 clocks are counted, and when the subtraction result becomes 0, flag B is reset in step 4-3. Therefore, when returning to the main routine, step 3-4 is passed and step 3-5 is executed to set the output port _F1 and turn on the paper feed signal PL.

In this way, the other operating equipment is lamp _L1 , motor _M2 for driving the drum, clutch OP for advancing the optical system, primary charger _HV1 , secondary charger _HV2 ,
The clutch CL for driving the timing roller also controls the timing.

Signal A in FIG. 10 is an output signal of the F/F connected to interrupt port IB, and signal B is a drum clock signal input to IB. F/F
(Signal A) is reset by the rising edge of B signal,
Disable interrupts to port IB. Further, once the A signal is set by the acceptance command (step 3-34-4), it is not reset until the rising edge of the B signal is detected. The same applies to port IA. or,
Interrupt port IA is used for processing interrupts with a higher priority than IB.
By connecting a trouble detector to IA and the aforementioned clock generator to IB, when the trouble detector detects an accident within the copying machine, it is possible to immediately issue an alarm or stop the copying machine operation.

That is, the F/Fs of IA and IB are set, and IA and IB are set first.
When an interrupt signal is input to
Execute the ROM program. Therefore, clock signals to IB are not accepted. On the other hand, if a clock signal is first input to IB, only the F/F of IB is reset. Therefore, when a trouble signal is subsequently generated in IA, the trouble signal is input and the copying machine is stopped, regardless of whether an interrupt is being applied to IB (input of drum clock CL).

Figure 11 shows that after determining whether a COPY command has been issued in STEP 2, the IA F/F is set in STEP 11, and
This is a flowchart illustrating steps 3 and subsequent steps for clock counting described above to complete the copying process. No matter where the accident occurrence signal X occurs at any step in this process cycle, that step is interrupted and the IA-START interrupt flow is executed, and the high voltage power supplies HV ₁ , HV ₂ , heater H, lamp L ₂ ,
The developing device M ₂ and drive system OP are turned off, and the display device DIS is turned on to shift to the end cycle. This turns off the operation of the copying machine (drum motor M ₁ , lamp L ₁ , clutch CL). The alarm DIS is reset by pressing a reset button (not shown) after applying safety devices against this accident.

Here, the accident detection circuit includes a detection circuit for abnormal temperature inside the copying machine (inside the fixing device) and a paper ignition detection circuit. It is also possible to use a device that detects the absence of transfer paper and developer in the cassette (see Fig. 1, 23a,
b) Furthermore, it is also possible to detect a jam (paper jam) in the transfer paper path or to detect a paper feeding error from a cassette. In addition, if a circuit that detects paper jams or paper feeding errors is connected to the interrupt port, the generation of a detection signal causes the sequence to shift to the post-drum rotation cycle immediately before the end cycle, thereby removing static electricity from the surface of the drum. can be stopped in any state. As an example of a paper jam detection circuit, a timer is activated at the start of paper feeding, and if the paper detector 2 (Fig. 1) at the outlet of the passage detects paper within a predetermined time (timer), the timer is reset, and when no paper is detected, the timer output is used as a detection signal. This is possible by using the timer output as a detection signal when the paper does not pass through the detector 2 within a predetermined time (another timer).

In addition, the paper feed error detection circuit operates a timer when paper is fed, and when a paper detector (not shown) installed near the paper feed roller does not operate within a predetermined timer period, the timer output is used as a detection signal. There is one that detects the feed and uses it as a signal.

An example in which both sequence control and jam detection are executed by pulses input to the interrupt port IB will be described below. This allows a small number of interrupt ports to be effectively used for different types of processing.

12A, B, and C are detailed flowcharts of FIG. 11, shown in a command word mode similar to FIG. 8a. Each step corresponds to a μPD545 instruction code. The meaning of the code is μPD454
This is omitted as it is clear from the manual. To explain briefly, after turning on the power to μCOM (START) and prohibiting IA reception in step 1, the number of sheets is set.
Enter the copy key (step 2), enable IA reception (step 3), turn on the motor M, lamp _L1 , DC charger HV1, and roller clutch CL in step 4, and turn on the motor M, lamp L1, DC charger _HV1 , and roller clutch CL in step 5. It is determined that the drum home position has passed the switch DHP and AC charger HV ₂ is turned on (step 6). In step 7, set the number of clock pulses CP to turn on the paper feed roller to 250.
In step 8, the interrupt flag is set in RAM, and the F/F is set to enable IB reception.

FIG. 13 shows the RAM storage section. Furthermore, DP←
1, 13, DP←6 are respectively (DP _H ,
DP _L ) indicates the addresses (1, 13) and (0.6),
DP1 indicates the data of the 1st bit of this address. If the pulse CP is not input to port IB, the subroutine SUBP for display in step 9 is repeated. When pulse CP is input, resets the F/F corresponding to port IB and disables IB reception.
(disable) and interrupt routines
Migrate to INTERUPT SUBPOUTINE. 1st
At step 10 of the interrupt routine in Figure 2C, the data in the accumulator ACC and register TR are retired to appropriate addresses in the RAM. In step 11, it is determined whether the number of pulses for timing operation has been set, and if it has been set, the process proceeds to step 12 and -1 is subtracted from the set number. Subtraction result 0
If not, proceed to step 14 and determine whether the number of pulses for jam detection has been set.Since it is not set now, proceed to step 15, recall the ACC and TR data from RAM, and enable reception of port IB. (enabled) and return to step 9 to perform the display routine again. When 250 pulses are counted, the interrupt flag is reset in step 13,
Go through steps 14 and 15 and proceed to 16. In step 16, it is determined whether the stop key has been input, and if it has been input, chargers HV ₁ and HV ₂ are turned off (step 17), and reception to port IB is prohibited (step 18), and the drum home position is set to DHP. Rotate the drum until it is detected. Then turn off motor _M1 lamp _L1 and roller clutch CL (step
20), key entry routine again (step 2)
Return to

When the stop key is not input, the paper feed plunger is turned on, the timing roller is turned off, and paper is fed (step 21). In step 22, the number of pulses for driving the timing roller is set and counted to feed the paper so that the developed image and the leading edge of the paper coincide with each other in the transfer section. At step 23, the paper feed plunger is turned off and the timing roller is turned on. step 24
Perform several sets, counts, and turns off to turn off the timing roller. At steps 25 and 26, wait for DHP to turn on and turn off.
Activate exposure lamp L ₂ and development motor M ₂ (step
27) Then, count 22 pulses, turn on the optical system drive clutch OP and roller clutch CL, and start exposure scanning (steps 28 and 29).

At step 30, the number of pulses for completing the exposure scan is set and counted.

In step 31, it is determined whether a jam flag, which is set when a jam is detected, is set. Since the jam flag is not set now,
Proceed to step 32.

In step 32, the number of pulses 228 for jam detection is stored at addresses (1, 11) in the RAM. Then, the count flag at address (0, 6) is set. The pulse in this case is called CP ₂ .

At step 33, the lamp L ₂ and clutch OP are turned off, and the optical system is returned to the exposure starting position using a spring or the like.

In step 34, it is checked again whether the STOP key is on, and if it is off, the jam flag is determined again, and if the flag is not set,
Add 1 to the copy number of the specific RAM address and compare it with the RAM set number stored in the key entry in step 2. If they do not match, return to step 21.
Paper is fed again for the next copy.

If it is determined in steps 34, 35, and 36 that the STOP key is turned on or the jam flag is set, and that the copy number and set number match, the program proceeds to step 37 (not shown) and turns off the AC charge. Then, in step 38, count CP ₁ to 149, turn off the DC charger (step 39), rotate the drum once, and then turn the switch on.
Determine whether DHP is on (step 40) and proceed to step
41, reset F ₀ , F ₂ , F ₄ , and F ₅ and stop motor M, lamp L ₁ , clutch CL, and jam indicator. At step 42, IBIA reception is disabled, and at step 43, the CP ₁ and CP ₂ flags for pulse counting are reset, and the process returns to key entry (step 2). If the number of copies does not match the set number in step 36, and if the interruption is successful with a drum pulse in step 22, steps 10 to 14 are executed as described above, but CP ₂ for counting pulses for jam detection is executed. Since the flag is set, proceed to step 48. In this step, the set number 228 is subtracted by 1 in the same manner as step 12, and if it does not become 0, the process returns to the original state via step 15. After setting 228 (CP ₂ flag), an interrupt is generated to IB every time a pulse arrives and step 48 is executed. However, counting for timing output is inhibited at step 11 unless flag _CP1 is set. When the pulse count reaches 0, reset flag CP ₂ and check input port K ₄ (step
49). If paper is not detected in the exit detector 2 at this time, the input of IA is prohibited, _F9 is set, the jam indicator is turned on, the jam flags of RAMs 0 and 5 are set (steps 50 and 51), and the process returns. Then, reset _F6 (AC charger) via steps 22 and 28 (step 37). Transition to the end mode. If paper is detected, step 15
Go back through , set 228 again at the end of exposure, and repeat the above steps. During the step, ACC←→[DP] also changes the contents of the accumulator.
is to exchange the contents of the data pointer,
DP _H ←DP _H VO means not changing the row of RAM. As described above, each time a pulse is input to one input port IB, a processing routine for forming a timing control signal (steps 12 and 13) and a processing routine for detecting an abnormality in the device (steps 48 to 48) are executed.
51) and an interrupt program (12th-C)
), the former processing routine is executed under the flag condition (step 11) on the sequence, but the latter processing routine is executed under the other flag condition (step 11).
14). That is, each processing routine is selected in accordance with the sequence and is caused to process the interrupt program. Therefore, although one common interrupt terminal is used, different interrupt processing can be performed separately. Below are examples of other interrupt terminals IA. The interrupt routine INTERUPTSUBIA detects a paper feed error. When paper is fed diagonally from the cassette and a well-known skew detector (not shown) near the exit of roller 25 is activated, step 51 sets port _F5 , lights up the indicator, and jumps to step 17. It is. Further, the IA and IB ports are triggered when the input level exceeds a predetermined level. The present invention makes good use of this point, and even if analog changes in the detection voltage by the thermistor Th are directly input to the IA as shown in FIG. 6, the desired detection operation can be changed depending on the setting of the peripheral resistance value. In other words, there is no need to convert to digital quantities. For example, the above effect can be obtained even if a well-known optical detector for detecting toner concentration is connected here, and a predetermined decrease in concentration can be detected and toner replenishment control can be performed to maintain a constant concentration. Similarly, a change in the voltage of Th due to a temperature drop is detected by the IA, and energization of the fixing heater is controlled, thereby maintaining the temperature at a constant temperature. In addition, a surface electrometer is connected to this IA to detect changes in the surface potential of the photoreceptor and control the chargers HV ₁ , HV ₂ or developer bias voltage, thereby maintaining a constant potential or image density. .

IA has a high degree of urgency, such as the above constant control.
Things that can be relatively delayed, such as no paper or toner, are connected to the IB.

If there are three or more interrupt ports, it is effective to arrange and connect these detection units according to the degree of urgency.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a copying apparatus according to the present invention, FIG. 2 is an operation time chart of the apparatus of FIG. 1, and FIG.
The figure is an example of a flowchart for timing control, Figure 4 is a time chart of drum clock and computer clock, Figure 5 is an example of a flowchart for process sequence control according to Figure 3, and Figure 6 is a control according to the present invention. Circuit example: Figure 7 shows the internal circuit of the μCOM element in Figure 6, Figures 8a, b, and 9 are flowchart examples for sequence control in Figure 6, and Figure 10 shows the interrupt reception. The time chart shown in FIG. 11 is a further example flowchart according to FIG. 6 of the present invention, and FIG. 12-A,
12-B and 12-C are detailed flowcharts of FIG. 11, and FIG. 13 is a bit diagram of the RAM.

Claims (1)

[Scope of Claims] 1. A recording medium, an operating means for forming an image on the recording medium, a pulse generating means, a main program for controlling the operating means to form an image, and a program executed during interruption of the main program. a program memory storing an interrupt program having both a processing routine for forming a timing control signal and a processing routine for detecting an abnormality in the device; an input port of the control means, an address storage means for saving the address of the main program in the program memory while the interrupt program is being executed, and one of the input ports of the control means is connected to the pulse generation means. Each time a pulse is input from the pulse generating means to the one input port, the address of the main program is saved in the address storage means and the program is interrupted, and each time the pulse is input, the The interrupt program having both a processing routine for forming a timing control signal and a processing routine for detecting an abnormality in the device is processed, and the processing routine for forming the timing control signal and the processing routine for detecting an abnormality in the device are processed. A program control method characterized in that one of the following is selected according to the sequence and the program is processed, and after the processing is completed, the save address stored in the address storage means is read out and returned to the original main program. image forming device.