JPH0213303B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a copying machine controlled by a microcomputer. The present invention relates to a copying machine whose drive is controlled by a microcomputer.

FIG. 1 shows a slit exposure type electrophotographic copying apparatus 10 with a moving optical system. The optical system is configured to scan to the left in the figure, and to start the copying operation by turning on switch SW1, such as a reed switch, located at a position corresponding to the leading edge of the document. It constitutes a system scanning mechanism A. Original table 14
An original (not shown) placed on the screen is continuously irradiated by an exposure lamp 11, and the reflected light (shown as a straight line) is reflected by the reflecting mirrors 12, 13 and the imaging lens 1.
5. Photosensitive drum 18 via reflecting mirrors 16 and 17
It is starting to reach . The photosensitive drum 18 is rotationally driven in the counterclockwise direction in the figure by the rotational force of the drive motor being transmitted through an electromagnetic clutch (not shown), and its surface is charged by a charging charger 19. After that, image exposure is performed by the optical system to form an electrostatic latent image of the document, and the image is developed by the developing device 23 to form a visible image with toner, which constitutes the image forming mechanism B. There is.

On the other hand, the copy paper (not shown) of a predetermined size stored in the paper feed cassettes 20a and 20b, respectively, is transmitted with the rotational force of the drive motor.
A copy paper supply mechanism C having selectively driven paper feed rollers 21a and 21b feeds one sheet to the lower part of the photoreceptor drum 18, and a transfer mechanism D having a transfer charger 24 uses a magnetic brush method. Then, the toner image of the electrostatic latent image formed on the surface of the photosensitive drum 18 is transferred onto copy paper. The copy paper subjected to the transfer process is peeled off from the photoreceptor drum 18 by a separating claw 25, and
The sheet is transported to the fixing mechanism F by a copy paper transport mechanism E, which has a transport roller 22 driven by the rotational force of the drive motor, and a transport belt 27 incorporating a static elimination charger 26. The fixing mechanism F
has a heat roller 28 and a press roller 29,
The copy paper is passed between the rollers 28 and 29 to fuse and fix the toner image. Thereafter, the copy paper is discharged onto a tray 31 by a discharge roller 30, and the photosensitive drum 18 is driven to rotate for a predetermined period of time, and residual toner is removed by a cleaning device 32. In this way, one copy process is completed. It's starting to end.

The copying operation of the copying apparatus 10 having the above configuration will be explained with reference to the time chart shown in FIG.

First, when the print command signal generating means (not shown) is activated, if the lower cassette 20b of the two-stage cassette is selected, the lower paper feed roller 21
At the same time that the actuation signal b is output, a timer TA that defines the output time of the actuation signal is started. In response to the actuation signal, the lower paper feed roller 21
While the copy paper is fed by b, the exposure lamp 11 is preliminarily turned on at a predetermined constant voltage, and the power to the heater of the heat roller 28 of the fixing device F is turned off.
Then, the photosensitive drum 18 starts rotating. The time measured by the timer T-E is set to a time sufficient for the tip of the copy sheet sent out by the lower paper feed roller 21b to come into contact with the intermediate roller 22a and form a loop to some extent. . Then, when the timer TA ends, the paper feed roller 21b stops and its conveyance is temporarily stopped. Lower paper feed roller 21
Timer T-B starts at the same time as the drive of b stops. The timer T-B defines the charging start timing, and the charging charger 19 is turned on when the timer T-B times out.

When timer T-B times up, delay timer T-C starts. This delay timer T-C
This defines the ON timing of the scan clutch that scans and moves the intermediate roller 22a and the optical system, and the actual lighting start timing of the exposure lamp 11. When the delay timer T-C times up, the scan of the optical system and the exposure lamp 11 are The main lighting and driving of the intermediate roller 22a are started. At the same time as the driving of the intermediate roller 22a starts, the timer T-A
is activated again, and when the timer T-A times up, the driving of the intermediate roller 22a is stopped. still,
Intermediate roller 22a and registration roller 2
2b is configured to be equal to the distance from the upper paper feed roller 21a.

That is, when the print command signal is generated while the lower paper feed cassette 20b is selected,
In response to the print command signal, preliminary lighting of the exposure lamp 11 is started, and the lower paper feed roller 21b
Immediately turn on the
a, and at a predetermined timing (a series of Immediate T-A after the print command signal is generated,
After the time-up of T-B and T-C), the intermediate roller 22a is turned on and the copy paper is sent to the registration roller 22b. intermediate roller 2
2a stops driving when the timer T-A times up, and the conveyed copy paper forms a loop with its leading edge in contact with the registration roller 22b and stops.

On the other hand, if the print command signal is generated while the upper paper feed cassette 20a is selected,
Unlike when the lower paper feed cassette 20b is selected, the upper paper feed roller 21 is activated in response to a print command signal.
Preliminary lighting of the exposure lamp 11 is started without driving the a. Further, in response to the print command signal, timer TA and timer TB are operated in sequence, and the charging charger 19 is turned on at the timing when timer TB times out. Furthermore, at the same time as the charger 19 is turned on, the delay timer T-C is activated.
is activated, and at the time of time-up, driving of the upper paper feed roller 21a, scanning operation of the optical system, and main lighting of the exposure lamp 11 are started. Note that at this time, the intermediate roller 22a is not driven. Also, at the same time as the drive of the upper paper feed roller 21a starts, the timer T
-A is activated again, and when the timer T-A times out, the driving of the upper paper feed roller 21a is stopped. The leading edge of the copy paper conveyed by the upper paper feed roller 21a is transferred to the registration roller 2.
2b, it forms a loop and stops.

That is, when the print command signal is generated while the upper paper feed cassette 20a is selected,
In response to the print command signal, lower paper feed roller 2
1b, preliminary lighting of the exposure lamp 11 and driving of the charger 19 are started at a predetermined timing, and furthermore, after the print command signal is generated, a series of timers TA, T-B, T- is started. C
After the time has elapsed, the upper paper feed roller 21a is
Turn on and place the copy paper on registration roller 2.
I am sending it to 2b.

As described above, the distance from the upper paper feed cassette 20a to the registration roller 22b,
Although the distance from the lower paper feed cassette 20b to the registration roller 22b is different, the copy sheets are controlled to be fed to the registration roller 22b at the same timing regardless of this difference. In this embodiment, when the upper paper feed cassette 20a is selected, a series of timers T-A, T-B,
After the time-up of T-C, the upper paper feed roller 21a
If the lower paper feed cassette 20b is selected, a series of timers T-A, T-B, T- are activated after the print command signal is generated.
After the time-up of C, the intermediate roller 22a is driven, and in either case, after the print command signal is generated, a series of timers T-A, T-B,
After the time-up of TC and TA, the copy paper reaches the registration roller 22b.

Next, when the lower paper cassette 20b is selected, the intermediate roller 22a is started after a predetermined time after scanning of the original starts, and the intermediate roller 22a is activated.
When the timer T-E starts at the same time as the registration roller 2a,
b is started, and the copy paper is fed to the photosensitive drum 18. Further, the intermediate roller 22a stops when the timer T-K, which starts at the same time as the intermediate roller 22a, times up, and the registration roller 22b stops when the timer T-N, which starts at the same time as the intermediate roller 22a stops, times up.

On the other hand, when the timer T-G (the operating time of this timer is variable depending on the paper length and magnification) starts at the same time as the above-mentioned timers T-E and T-K, the scanning of the optical system stops and the lamp starts running. goes out, and the optical system starts returning when the timer TV, which starts at the same time as the scanning stops, times up. Furthermore, at the same time as the optical system stops scanning, the next (second) copy sheet is fed and sent to the position where it reaches the intermediate roll 22a. A second scan of the manuscript was then carried out,
After a predetermined time, the intermediate roller 22a is restarted, and the registration roller 22b is activated when the timer TE, which starts at the same time as the intermediate roller 22a, times up. Thereafter, the same operations as described above, such as stopping the intermediate roller 22a and stopping the registration roller 22b, are repeated.

On the other hand, when the upper paper feed cassette 20a is selected, the control after starting document scanning is substantially the same as that of the lower paper feed cassette described above, except that the intermediate roller 22a and the lower paper feed roller 21b are not driven. This is the same as the paper feeding control from 20b.

As described above, in a copying machine that uses a plurality of copy paper sizes, complicated sequence control and various types of time measurement are required. Furthermore, in order to increase the speed of copying during continuous copying, it is necessary to change the operating time of the registration roller depending on the size of the copying paper used. To meet these demands, conventional control circuits that combine relays, etc. are insufficient, but by using a microcomputer, complex sequence control and timekeeping functions can be achieved with a simple device. Extremely advantageous.

Microcomputers used in copying machines usually have a processing time of about 10 μsec for one instruction.
If the number of processing steps required to control a copying machine is, for example, 1000 steps, a microcomputer can handle approximately 1000 steps.
Process in 10msec (10μsec x 1000) (hereinafter, 1000
(The processing of each step is called one routine, and approximately 10 msec is called one routine time.) That is, the microcomputer executes sequence control of the copying machine by repeating the same process approximately every 10 msec.

In a conventional copying machine using such a microcomputer, the registration roller 22b is controlled using the signal of the exposure switch SW1 operated during scanning as a reference signal, for example, as shown in the flowchart of FIG. I was worried.

That is, in step 100, the exposure switch is
SW1 was turned on (the optical system was turned on by the exposure switch SW1).
) and then set the exposure switch SW.
If 1 is ON, timers T-K, TG, and TE are set in step S200. In step S300, it is determined whether or not the timer T-E has expired, and if it has finished, the process proceeds to step S4.
00 to output the registration roller drive signal. In step S500, it is determined whether or not the timer T-K has expired. If it has finished, the timer TN is set in step S600. In step S700, it is determined whether or not timer T-N has expired, and if it has finished, step S700 is performed.
At 800, driving of the registration roller 22b is stopped. Note that the flowchart specifically shows only the processing steps related to the control of the registration roller 22b, and describes other controls, such as determining various input signals, searching for sequence control switches, and outputting timing signals to each internal device. ,
Each abnormality process such as jam detection is composed of a plurality of process steps, which are expressed as four other processes.

A series of processing steps (one routine) starting from the above-mentioned processing and ending with the processing from step S100 to step S800 is executed at a cycle of about 10 msec. Each processing step appearing in one routine is executed only once in one routine. In other words, each processing step is approximately
Executed once every 10msec.

For example, the process of step S100 for determining the state of the exposure switch SW1 is executed at a predetermined timing in one routine, and then executed at a predetermined timing in the next routine. Therefore,
Step S at a predetermined timing in a certain routine
When step 100 was executed to determine the state of exposure switch SW1, exposure switch SW1 was not turned on, but immediately after that determination, for example, while executing the process indicated by process, exposure switch SW1 was turned on. Even if the exposure switch SW1 is used, it is no longer possible to determine the state of the exposure switch SW1 during that one routine. In times like this,
The process waits for the determination in step S100 of the next routine. Therefore, the microcomputer is
When the exposure switch SW1 is turned on, it is actually turned on.
Detection is performed after a delay of at most one routine processing time (10 msec) from the time when the detection occurs.

The mechanism by which the above delay occurs will be explained in more detail using the timing chart shown in FIG. In the microcomputer, the search signal IP is issued once during each routine, and whether the exposure switch SW1 is activated or not depends on the search signal.
The exposure switch SW1 judgment step S determines whether the switch SW1 is “H” during the IP pulse period.
This is done by making a determination based on 100. If the level is not "H", the timer TE, which determines when to start the registration roller 22b, is not driven. Therefore, as shown by the dashed line in Fig. 3, the switch SW1 goes high immediately after the signal IP ends.
, the search signal IP (IP
2) occurs, the timer TE is set for the first time. Then, the maximum error in the starting time of timer TE is the time required for one routine of the microcomputer. As described above, since the time required for one routine is about 10 msec, the activation timing of the registration roller 22b is delayed by 10 msec. Such a 10 msec timing deviation is hardly a problem in a copying machine with a slow copy paper feeding speed, but for example, in a high speed copying machine with a feeding speed of about 200 mm/sec, the above 10 msec timing deviation is corresponds to a deviation of 2 mm on the copy paper, which is a non-negligible size for the registration rollers that directly affect the position of the copied image, resulting in the problem that the copy cannot be made at an accurate position.

SUMMARY OF THE INVENTION An object of the present invention is to provide a copying machine controlled by a microcomputer that eliminates the problem that the image forming position shifts depending on the operating timing of the exposure switch.

An embodiment of the present invention will be described below with reference to the drawings.

The embodiments described below are applied to a copying machine having the configuration shown in FIG. 1 and operating according to a time chart roughly shown in FIG. 2.

In FIG. 4, 40 is a microcomputer, which includes a ROM, RAM, CPU, shift register (not shown), etc., and is controlled according to a predetermined program stored in the ROM.

Reference numeral 42 denotes a registration roller activation control unit according to the present invention, 43 a solenoid for a clutch for driving the registration roller, and 44 a switch for instructing activation of the registration roller. The switch 44 is provided in the middle of the movement path of the scanning device and is operated by a moving body for scanning the original. More specifically, the switch 44 is
The distance between the position corresponding to the leading edge of the original image formed on the photosensitive drum 18 and the transfer position becomes equal to the distance between the leading edge position of the copy paper held by the registration roller 22b and the transfer position. It is provided at a position where it is sometimes turned on by a moving object. The switch mounting position that satisfies the above conditions can be easily calculated and determined based on the moving speed of the moving body and the rotational speed of the photoreceptor.
This switch 44 is connected via a resistor 46 to the base of a transistor 47 that controls on/off the solenoid 43.
When turned on, the transistor 47 turns on,
The solenoid 43 is activated to start the registration roller 22b. In addition,
The switch 44 is kept on for a longer time than the time required for one routine of the microcomputer 40. That is, the registration roller 22b is activated by the switch 44, and is kept in an on state by the switch 44 for a longer time than the time required for one routine.

Transistor 48 is microcomputer 40
is an amplifier that matches the output of the transistor 47 with the required input value of the transistor 47. Its input side is connected to the output terminal of the microcomputer 40, and its output side is connected to the base of the transistor 47 via a resistor 46. There is.

50 is a DC power supply, 51 is a diode for preventing solenoid back electromotive force, and 52 is a current limiting resistor of the transistor 48.

One input terminal of the microcomputer 40 has an exposure switch that is turned on during the scan operation.
SW1 is connected, and this exposure switch SW
1 is connected to the output line 54 of the microcomputer 40, and from the microcomputer 40
When the search signal is issued once in each routine, the state of SW1 is checked, and if it is ON, it is input to the microcomputer 40 via the input line 53, and timer T-K, timer T-E, and timer T- It is now starting G.

As mentioned above, the switch 44 is set to remain on for a longer time than the time required for one routine of the microcomputer 40, so no matter what timing the switch 44 is turned on, it means that the microcomputer It is reliably detected by the search signal that is output once per routine.

When the timer TE times up, the microcomputer 40 outputs an output signal from the signal line 55. This output signal is applied to the base of transistor 48 via resistor 56, turning on transistor 47. When the transistor 47 is turned on, the collector and emitter of the transistor 47 are electrically connected, and the transistor 47 is turned on regardless of the state of the switch 44, and the solenoid 43 is turned on.
This output signal from the microcomputer is supplied until timer TN times up.

That is, the registration roller 22b starts to be driven at the timing when the switch 44 is turned on as the optical system moves, and while the switch 44 remains on, the microcomputer 40
The drive is continued by the output signal output from the microcomputer even after the switch 44 is turned off, and the drive is stopped when the output signal from the microcomputer is stopped when the timer TN times up.

The microcomputer 40 is provided with a clock mechanism that constitutes the timers TE, TK, TN, TG, TV, etc. This type of timekeeping mechanism is well known and consists of clock pulses, shift registers, and the like. Further, the microcomputer 40 is provided with a control section that performs charging, lamp blinking, forward/reverse scan, etc. according to the time chart shown in FIG. Furthermore, regarding the drive of the registration roller 22b, the control section outputs a registration roller 22 drive signal according to the procedure of the flowchart shown in FIG. 5, and also stops the registration roller 22b. It is programmed to carry out the control.

Next, the operation will be explained.

Assume that the electrophotographic copying machine shown in FIG. 1 is operated under the control of the microcomputer 40 to a position A in the time chart of FIG. 2 where scanning of an original starts.

While the original is being scanned, press the exposure switch SW.
1 is turned on, a signal from the exposure switch SW1 is applied to the microcomputer 40, and starts timers TE, TK, and TG.

Before the timer T-E times up, the switch 44 is turned on as the optical system scans, and the signal from the switch 44 is applied to the base of the transistor 47 via the resistor 46, turning on the transistor 47 and turning on the solenoid. 43 is turned on. As a result, the registration roller 22
b is activated immediately, and the copy paper is fed into the photosensitive drum 18.

On the other hand, when timer T-E times up,
The microcomputer 40 sends the signal to the transistor 47 via the amplifier 48 and the transistor 4
Drive 7.

As a result, even after the switch 44 is turned off, the transistor 47 remains on for a predetermined period of time, keeping the registration roller 22b in a driven state.

Further, the intermediate roller 22a stops after the timer T-K times out. At the same time, timer T-
After the time-up, the signal generated on the line 55 from the microcomputer 40 disappears, the output of the amplifier 48 is also turned off, the transistor 47 and the solenoid 43 are turned off, and the registration roller 22b is stopped. do.

When the second document is scanned and exposure switch SW1 is turned on, timers T-E and T
-K and T-G are restarted, and then the switch 44 is turned on in the middle of scanning, the transistor 47 is turned on again in the same manner as described above, and the registration roller 22b is activated. Thereafter, the same operations as described above are repeated.

As described above, according to the present invention, various timing and sequence controls are performed by a microcomputer, so the control system can be configured easily, and the registration roller can be started by an external start switch. Since this is done directly using the signal from the start switch, a discrepancy between the timing at which the start switch signal is generated and the scanning timing of the microcomputer can cause, for example, the start time of the registration roller in an electronic copying machine to shift. Problems such as misalignment of the copy position do not occur. In addition, since the activation timing of the registration roller is directly determined by the activation switch, the activation accuracy of the registration roller can be improved by accurately mounting the activation switch. Even if there is a discrepancy in the start timing of the registration roller, it can be easily adjusted by adjusting the mounting position of the start switch.

Furthermore, only the start time of the registration roller is determined by the start switch, and continuous drive control of the registration roller is performed by signals from the microcomputer as before, so the program of the microcomputer can be changed. There is no need to make any changes, and there is no need to provide a separate drive continuation control circuit, so an increase in cost can be avoided.

[Brief explanation of drawings]

Figure 1 shows an example of an electrophotographic copying machine, Figure 2 shows an example of an electrophotographic copying machine.
Figure 1 is a time chart showing the operation of the device shown in Figure 1, Figure 3 is a diagram showing the drawbacks that occur when time is measured by applying input from an exposure switch to a microcomputer, and Figure 4 is an example of an implementation of the present invention. FIG. 5 is a circuit diagram showing an example, and is a flowchart showing the main part of the operation of the microcomputer of the device shown in FIG. 18... Photosensitive drum, 22a... Intermediate roller, 22b... Registration roller, 40
... Microcomputer, 43 ... Solenoid, 44 ... Switch (for starting the registration roller), 47 ... Transistor, SW1 ...
Exposure switch.

Claims (1)

[Scope of Claims] 1. A copying cycle in which an image is formed on a rotating image carrier and the image on the image carrier is transferred in a transfer section onto a recording medium conveyed through a conveyance path. In a copying machine in which the copying cycle is controlled by a microcomputer repeatedly executing a routine consisting of a plurality of steps, a recording medium and an image carrier are provided in front of the transfer section and are conveyed. It is operated by a registration roller for synchronizing with the image on the image carrier, and a moving body driven in synchronization with the image forming operation on the image carrier, and is executed in one routine of the microcomputer. switching means for generating an actuation signal for a longer time than the required time; switching means for causing the actuation signal from the switching means to initiate the operation of the registration roller and for causing the operation of the registration roller to continue for the generation time of the actuation signal; A copying machine comprising: a control circuit that continues the operation of the registration roller by an operation control signal output from the microcomputer within the time period in which the operation signal from the switching means is generated.