JPS6395473A - Control method for switching developing device of picture forming device - Google Patents

Abstract

PURPOSE:To quickly complete switching of developing devices when the switching operation is stopped in the course of the switching and the same developing device is again selected, by setting the restarted developing device switching operation time shorter by the quantity corresponding to the progress of the switching operation and performing the switching operation. CONSTITUTION:When a switching stopping signal is inputted from the outside during the course of the switching operation, the switching operation is stopped. If the developing device of which the switching operation is stopped is again selected and its selecting signal and print switch turning-on signal is inputted thereafter, time counting is started by setting the switching operation time shorter that a prescribed switching operation time by taking the already spent switching operation time into consideration and, at the same time, switching operation of the developing device is restarted. Then it is regarded that the switching operation is completed when the set switching operation time has passed and the picture forming operation is caused to be started. This developing device switching control is executed by means of the software of a microprocessor. Therefore, the switching operation can be made in a period which is shorter than the ordinary switching operation and no time loss occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling switching of developing devices in an image forming apparatus equipped with a plurality of developing devices that can be selectively switched and used.

[Conventional technology]

An electrostatic photographic image forming apparatus is equipped with multiple developing devices for the purpose of making color copies in addition to black copies, and the desired developing device is operated by selecting one of these using the operation/ξ channel selection key. A device having such a configuration is publicly known.

In this type of image forming apparatus, the switching operation of the developing device,
For example, when it is desired to make a color copy after making a black copy, an operation called a cutting operation is required to collect the smoked color developer remaining on the developing sleeve. If this operation is insufficient, black toner will also adhere during subsequent color copying, making it impossible to obtain a clear image. A predetermined time period, for example, about 4 seconds, is set for this switching operation of the second developing device to ensure that the developer on the developing sleeve is collected.

[Problem that the invention seeks to solve]

In the above-mentioned conventional image forming apparatus, after starting the switching operation of the developing device, if it is realized that there is no need to switch the developing device, the stop key is operated to stop the started switching operation of the developing device. Can be done. Then, when the same developer as the developer whose switching operation was previously stopped is selected again, a predetermined time is set again for the switching operation of the developing device, and the switching operation is started. In such a case, since the developer on the developing sleeve has been recovered to some extent by the switching operation of the developing device that was previously performed halfway, the restarted switching operation will take a shorter time than the normal switching operation. However, even in this case, the copying operation cannot be started until the predetermined switching operation time has elapsed, resulting in a corresponding loss of time.

[Failure to solve the problem]

In order to solve the above-mentioned problem, the present invention has been made such that when the switching operation of a selected developing device is started and then stopped, and the switching operation to the same developing device is started again, the restarted developing device switching operation is performed. This system sets a setting time shorter than the setting time for normal switching, and is equipped with a plurality of developing devices that can be selectively switched, based on a developing device selection signal input from the outside. In the image forming apparatus, the developing device switching control means selects a predetermined developing device from the plurality of developing devices and sets it in an operable state. The developer switching operation is started by setting a predetermined switching operation time based on When a developer selection signal for reselecting a developer is input, the developer switching operation is restarted by setting a switching operation time shorter than the predetermined switching operation time, and when the switching operation time has elapsed, the image forming operation is started. It is characterized by making it possible.

[For production]

A developer selection signal is input to the developer switching control means from a key switch on the operation panel of the image forming apparatus, and when the print switch is turned on, the developer switching control means selects a predetermined value based on the input developer switching signal. The switching operation time is set and timing is started, and at the same time, the switching operation of the developing device is started.

If a switching stop signal is input from outside during switching operation, the switching operation will be stopped. After that, when the developer whose switching operation was stopped is selected again and its selection signal and print switch ON signal are input, the predetermined switching operation time is shorter considering the elapsed time of the switching operation performed earlier. The switching operation time is set and timing is started, and at the same time, the switching operation of the developing device is restarted. Then, when the set switching operation time has elapsed, it is determined that the switching has been completed, and the image forming operation is started. More developer switching N? fJH is executed by microprocessor software.

〔Example〕

An embodiment of the present invention will be described below.

In this embodiment, the invention of this application is applied to a copying machine equipped with two developing units.

FIG. 1 is a cross-sectional view showing the main structure of a copying machine.
2 is a copying machine, and 2 is a photosensitive drum. The photosensitive drum 2 can be rotated and moved slightly in a counterclockwise direction by a main motor (not shown). The photosensitive drum 2
A charger 3, an inter-image eraser 4, first and second developers 5.
6, a transfer charger 7, a separation charger 8, a cleaner device 9, and a main motor 10 are arranged, and an optical system 0 is arranged above the photoreceptor drum 2 and its peripheral equipment.
A paper feed system P is provided on the left side, and a fixing device 11 is provided on the right side. Note that three or more developing devices may be provided.

The optical system 0 includes a scanning unit 14 formed by integrating a slit exposure type light beam 12 and a first exciter mirror 13;
It is composed of second and third movable mirrors 16 and 17 held by a common holder 15, a lens 18, and a fixed mirror 19. Then, the inter-image eraser 4 erases the photosensitive drum 2.
The charger 3 is designed to remove charges between the images, that is, in the area corresponding to before the front edge in the scanning direction and after the rear edge in the scanning direction of the original (not shown) set between the original glass 20 and the original holder 21. By positively charging the area corresponding to the original on the surface of the photosensitive drum 2, turning on the light source 12, and scanning the original while moving the scanning unit 14 to the left in the figure using a scanning motor (not shown). ,
An electrostatic latent image corresponding to the image of the original is formed on the photosensitive drum 2.

The moving speed V of the scanning unit 14 is
The circumferential speed of V. , if the copying magnification is m, then V=Vo/m is set, and the second and third movable mirrors 16 and 17 are set at V during scanning. / 2 m to the left in the diagram. Further, the scanning unit 14
is the fixed position switch 22 at all times, that is, during non-scanning.
to send a fixed position signal (to be described later) to the first CPU 200.
When the scanning unit 14 moves to the left by a predetermined distance after the start of scanning, in order to synchronize the scanning unit 14 and the paper feed system P. Then, the timing switch 23 is touched, and a timing signal (at the time when the scanning unit 14 touches the timing switch 23,
1'').

Negatively charged toner supplied from the selectively used first or second developing device 5 or 6 is attached to the surface of the photosensitive drum 2, and this toner forms the electrostatic latent image. is visualized (developed) to form a toner image corresponding to the image of the document. Subsequently, the toner image is transferred by the transfer charger 7 from the timing roller 24 located at the most downstream side of the paper feeding system P to a copy paper (not shown) that is supplied to the surface of the photosensitive drum 2 in synchronization with the above-mentioned timing signal. The transferred copy paper is further separated from the surface of the photosensitive drum 2 by a separation charger 8. Photosensitive drum 2
The copy paper separated from the paper is conveyed by the conveyor belt 25 to the fixing device 11, where the toner image is heated and
After being fixed, it is discharged onto the tray 2G.

The residual toner on the surface of the photoreceptor drum 2 is removed by the cleaner device 9 and collected in the cleaner device 9, and the residual charge on the surface of the photoreceptor drum 2 is removed by the main motor, which is always lit while the main motor is driving. 10.

The paper feeding system P includes a manual paper feeding section 27, a first cassette paper feeding section 28 (hereinafter simply referred to as the first paper feeding section 28), and a second cassette paper feeding section 30 (hereinafter simply referred to as the first paper feeding section 28). Copy paper inserted from the manual paper feed section 27 is conveyed to the timing roller 24 via the manual feed roller 31 and the intermediate roller 32, and
Cassettes 28a and 30a attached to paper feed section 28.3o
The copy paper inside is fed by the first and second paper feed rollers 331.3
4. The paper is conveyed to the timing roller 2.1 via an intermediate roller 32.

Each of the rollers 2, 1, 31, 32, 33, and 34 is driven by a main motor via a clutch (not shown), respectively. The rollers are detachably connected to the drive system, and by turning on the clutch of each roller, the rollers are connected to the drive system and rotated and driven by the main motor. Note that each cassette 28a.

In the vicinity of 30a, each cassette) 28a, 3Oa
size detection sensors 35, 36 for detecting the size of copy paper stored in the cassettes 28a, 37, 38 for detecting when the copy paper in each cassette 28a, 3Oa is exhausted. is installed.

Next, the structure of the developing device will be explained. FIGS. 1 and 2 are external views of the first developing device 5. Since the second developing device 6 is also almost the same, the first developing device will be explained. Note that the reference numerals in the figure enclosed in parentheses are the reference numerals of the second developing device.

A bracket 40 is provided at one longitudinal end of the first developing device 5, and a toner supply bottle 45 for replenishing toner into the first developing device 5 is detachably attached to the bracket 40. The toner replenishment bottle 45 is rotated by a replenishment motor (not shown) to be supplied with toner, and a developing motor (not shown) transports the replenished toner into the first developing device 5 and rotates the developing sleeve. , stirring operation is performed.

Near the toner replenishment bottle 45, there is a toner replenishment bottle presence sensor 41 that detects whether or not the toner replenishment bottle is attached.
A toner empty sensor 46 is attached to detect the presence or absence of toner in the toner supply bottle.

Magnets 47 and 48 that identify the color of the toner inside the developer can be attached to the upper part of the outer casing of the developer, and the attached magnet is attached to the side of the copying machine that faces the magnet 47 and 48. Eleventh and second reed switches 49,50 are provided for detection. As a result, for example, in the case of black toner, if two magnets 47 and 48 are attached, the first and second reed switches that detect this will both turn ON, and an identification signal indicating that it is black toner will be sent. is output. The length of the magnet 4'148 is 4.
Since the types can be combined, it is possible to identify the four colors of toner.

Next, the internal structure of the developing device will be explained with reference to FIGS. 3 and 4, and for convenience of explanation, the explanation will be given starting from the second developing device 6.

It is assumed that the second developing device 6 is loaded with black toner and is disposed on the downstream side in the rotational direction of the photosensitive drum with respect to the first developing device loaded with color toner.

In FIG. 3, reference numeral 71 denotes a toner replenishment gutter, in which the toner replenished from the toner replenishment bottle 58 described above is conveyed by a screw or the like (not shown) so that the toner is replenished uniformly in the width direction of the photosensitive drum. 72 is a packet for stirring the toner and magnetic carrier, 73 is a shutter and a developing sleeve 76
It replenishes developer (a mixture of toner and carrier) and blocks it.

FIG. 5 is a perspective view showing the shutter portion of the developing device,
Normally, the shutter 73 is in the open position shown in FIG. 3 under the action of an arm 79 pulled up by a spring 78.

Further, when the second developing device 6 is inactive and the ear cutting operation is performed, the ear cutting solenoid 80 is energized and the arm 79 is pulled down until it hits the stone ε-81.
Nyatta 73 assumes the closed position shown in FIG.

75 is a cylindrical magnet (hereinafter referred to as magnet) with seven magnetic poles formed on the periphery, S6 is fitted on the outer periphery of this magnet,
This is a developing sleeve rotated and driven by a developing motor (not shown).

When the second developing device 6 has the operating state button, the packet 72,
The developing sleeves 76 rotate in the directions of arrows a and b in the figure, and the developer is supplied from the packet 72 to the developing sleeve 76 through the upper surface of the printer 73 in the direction of arrow P in the figure. The developer supplied onto the developing sleeve 76 is carried in the direction of the arrow as the developing sleeve 76 rotates, but the magnet 7
When it comes to the top of the magnetic pole No. 5, a raised ear 77 is formed. When this spike 77 touches the electrostatic latent image on the photosensitive drum 2, toner adheres to the electrostatic latent image and development is performed. Thereafter, the developer is further carried along with the rotation of the sleeve 76, and the developer is further transported to the magnet 7.
It peels off from the sleeve 76 at the portion C where the magnetic pole of No. 5 is missing, moves in the direction of arrow R in the figure, and is collected into the packet 72.

When the second developing device 6 is placed in an inoperative state, the shutter 73
takes the closed position shown in FIG. The missing part of the magnetic pole C
The developer is peeled off from the developing sleeve 76, moves in the direction of arrow R in the figure, and is collected in the packet 72, so that there is no developer on the developing sleeve 76. In this state, the developing sleeve 76
If you stop the rotation, the ear cutting solenoid 80 will be turned off.
Even if the shutter 73 is returned to the position shown in FIG. 3, the developing sleeve 76 remains free of developer.

Next, when returning to the developing state again, by rotating the developing sleeve 76, spikes of developer 77 are instantaneously formed on the sleeve S6.

The first developing device 5 is not equipped with the shutter 73 of the second developing device 6, and a fixed guide plate is provided at the position where the shutter 73 is in the open state (see FIG. 3). This is similar to the second developing device 6.

Since the first developing device 5 is loaded with color toner, when color development is performed, when the first developing device is activated, the ears formed on the developing sleeve are transferred to the photosensitive drum 2.
Developing the upper electrostatic latent image is the same as the operation of the second developing device 6 described above. At this time, the second developing device 6 is in an inactive state and no spikes of black developer are formed on the developing sleeve, so that the image developed with the color toner does not come out.

Further, when developing the electrostatic latent image on the photoreceptor drum 2 with the second developing device 6, the first developing device 5 is set to an inactive state,
Rotation of the developing sleeve is stopped. and the first developing device 5
The developing bias is changed to make it difficult for toner to adhere to the electrostatic latent image.

As a result, even if spikes of color developer are formed on the developing sleeve, toner does not adhere to the electrostatic latent image, and the electrostatic latent image is then developed with the black developer in the second developing device, making it practical. There is no problem at all.Next, the operation channels of the copying machine 1 will be explained.

At the top of the copying machine 1, there is an operation panel 1 as shown in FIG.
00 is equipped, and the operation/gune 7 and 100 are equipped with
Print key 102 for commanding the start of copying, interrupt key ~1
03. Stop copying immediately after copying starts or in the middle of multi-copying (successive copying of multiple sheets based on the same original), clear the number of copies set on the number of copies display section 104 consisting of a group of LEDs, and switch to standard mode. a clear/stop key 105 for returning to 1", numeric keys 106 to 115 for setting the number of copies on the copy number display section 104, and the light source 1.
Exposure up key 1 to increase or decrease the exposure amount from 2
16, an exposure down key 117, an LED group A that is selectively turned on to display the exposure amount, and the first or second paper feed section 28.
Paper source selection key 118 to select 30, LED I to display the size of copy paper fed from the selected paper source
20 to 123, a first developer selection key 124 and a second developer selection key 125 for selecting the first developer 5 and second developer 6, respectively; L for displaying the selected developer 5 or 6;
ED 126 and 127, LEDs 128 to 131 that display the color of toner in the selected developing device 5 or 6, and whether the toner supply bottle 41 or 53 attached to the selected developing device 5 or 6 is empty. ), an LED 132 is provided to display it. In addition, in this embodiment, L corresponding to four color toners is displayed on the operation panel.
Although EDs 128 to 131 are provided, there are only two developing devices, and only the LED corresponding to the installed developing device functions.

Next, a control circuit for controlling the copying machine, such as the copying operation of the copying machine and the selection control of the developing device when the first developing device or the second developing device is selected, will be described.

Figure 7 is a block diagram of the control circuit.
microprocessors (CPUs) 200 and 300, the inner cylinder 1 and the CPU 200 have an operation channel 10.
Various keys on 0, 1st. Second bottle presence sensor 41.5
3. First and second bottle empty sensors 46.60, first to fourth reed switches 49.50 for detecting toner color
．． A switch matrix S consisting of 63, 64, etc. arranged vertically and horizontally is connected, and the operation of each key is based on the operation of sensors to control the aforementioned main motor, various roller clutches, etc.
The ear cutting solenoid 80 and the like are operated and controlled by the first CPU 200, and various LEDs such as the copy number display section 10.1 are turned on and off via the decoder 133.

On the other hand, the second CPU 300 is connected with the localization η switch 22, timing switch 23, etc.
The CPU 300 mainly operates and controls the optical system O. The first CPU 200 and the second CPU 300 are connected to each other for mutual synchronization.

Next, an outline of the operation of the control circuit will be explained.

First, the first or second toner loaded with the desired color toner is loaded.
Copy machine operation/ξ channel 1 to select developer 5.6
When the developer selection key 124 or 125 on 00 is pressed, a developer selection signal is input to the first CPU 200. Copy paper size, number of copies, etc. are also input to the first CPU 200 from the keys on the operation channel 100.

The first CPU 200 first checks whether the same developing device as the currently set developing device is selected based on the input developing device selection signal and print switch ON signal, and if it is the same developing device, the developing device is Copying starts immediately without changing the device. The control of the copying operation is the same as that employed in known copying machines, so a description thereof will be omitted. If a developing device different from the currently set developing device is selected, it is determined whether the selected developing device is the first developing device or the second developing device, and the A predetermined switching operation time required for switching is set in a timer provided in the first CPU to start timing, and a signal indicating the color of toner loaded in the selected developer is output and an LED is output.
Any one of 128 to 131 is turned on, and the switching operation of the developing device is started.

If the developer is selected incorrectly while the timer is operating, that is, during the switching operation, press the clear stop key 105 on the operation knob to transmit the switching operation stop signal to the first CPU.
Enter 200. When the switching operation stop signal is input, the first CPU 200 stops counting the timer, stores the count value of the timer in the memo IJB, and stops the switching operation of the developing device.

After this, the developer whose switching operation was stopped is selected again, and the developer selection signal and print switch ON signal are switched to the first CP.
When inputting to U200, the elapsed time from the start of the switching operation of the developing device stored in the memory when the switching operation was stopped first until the time when it was stopped is read out, and this is subtracted by a certain ratio to ensure safety. The time subtracted from the predetermined switching operation time set in the normal switching of the developing device above is set in the timer to start measuring time, and at the same time, the switching operation of the developing device is started. As a result, the switching operation time is shortened by a time corresponding to the amount of time that the switching operation has progressed, such as part of the developer being recovered in the previously executed switching operation of the developing device.

When the timer finishes counting, the switching operation of the developing device has been completed, so the copying operation is started.

Next, the control of the copying machine executed by the microprocessor, particularly the switching control of the developing device, will be explained with reference to the flowcharts of FIGS. 8 and 9.

FIG. 8 shows an outline of the main routine for controlling the copying machine. In step S1, register settings, timer,
Set initial values of flags, etc.

In step S2, an internal timer that defines the operating time of the main routine is set and time measurement is started.

In step S3, switching control of the developing device is performed.

This will be explained in detail later. In step S4, signals input from the copying machine operation, ξ channel, various sensors, etc. are processed. In step S5, processing is performed such as outputting various signals for controlling the copying operation of the copying machine and displaying output signals such as operation status. In step S6, the process waits for the internal timer to finish counting, and then returns to step S2 to proceed to the next cycle of processing.

Next, the developing device switching control shown as step S3 in FIG. 8 will be explained with reference to the flowchart in FIG. 9.

First, it is checked whether copy processing is in progress (step 5ll), and if copy processing is in progress, the process returns to the main routine immediately without entering developer switching control, but if copy processing is not in progress, step S1
Proceed to step 2 to check whether the print switch is turned on and a trigger signal is input. When the trigger signal is input, the process moves to step 513, and flag F, which will be explained later, is input.
Determine whether l is 1 or not, F1=! When F1=1, the process advances to step S14, and when F1=1, the process advances to step S16. In step 514, it is determined whether a flag F2, which will be explained later, is 1. If F24=1, the process proceeds to step 515, and if F2=1, the process proceeds to step 516. In step 515, it is checked whether the same developing device as the already set developing device used in the previous copying operation has been selected. If the same developer is selected, step 541
and start the copying operation. If the same developing device is not selected, the process advances to step S16, and it is checked whether the first developing device is selected. If the first developing device is selected, the process advances to step S17, and it is checked whether the flag F1 is 1 or not. When the flag F1 is not set to 1, a predetermined set value N is set as the count value N of the timer.

(step 518), and when flag F1 is set to 1, the count f value stored in memory B, which will be explained later, is read out to the A register, and the content (A) of this A register is given a margin. For example, 0.8
The value obtained by multiplying by a constant k such as , and subtracting this from the count value N [:N-k(A))] is set as the count value N (
Steps 519.520).

The timer starts counting the timer using the count value N as the timer value, and starts the switching operation to the first developing device.Step S2
1.522), flags F1 and F2 are set to O, and the process returns to the main routine (step 523).

As a result of the determination in step 816, if the first developing device is not selected, the process moves to step S24, and it is checked whether the second developing device is selected. If the second developing device is not selected either, the process moves to step S23, flags F1 and F2 are reset, and the process returns to the main routine; however, if the second developing device is selected, the process moves to step S25, and the flag F2 is set to 1.
Find out whether or not. When the flag F2 is not set to 1, a predetermined set value M is set as the timer count value M. (step 826), and when the flag F2 is set to 1, the count value stored in memory B is read to the A register, and in order to provide a margin for the contents (A) of this A register, for example, 08 The value obtained by multiplying by a constant k such as , and subtracting this from the count value M (M - k
(A) ) is set as the count value M (steps S27 and S28). The timer starts measuring time using the count value M as the timer value, and the switching operation to the second developing device is started. Steps S29 and 530), Step S23
Move to.

As a result of the determination in step 2, if there is no trigger signal, the process moves to step S31, and it is checked whether the timer is measuring time or not. If the time is being counted, the process moves to step S32, and it is checked whether the clear stop key is ON to stop the started developer switching operation, and if it is not ON, that is, to continue the switching operation, the process returns to the main routine. When the clear stop key is ON, the timer stops counting, the count value of the counter at that time is stored in the memo IJB, and the switching operation of the developing device is stopped (steps 533 and 534).

Furthermore, it is checked whether the developing device selected at that time is the first developing device or the second developing device, and if it is the first developing device, the flag F1 is set to 1.
When the developing device is the second developing device, the flag F2 is set to 1 (steps 535 to 37). Steps 532-S
When the developing device whose switching operation was stopped is selected again by the processing in step 37, steps 517 to S20 described above are performed.
, steps 325 to 528, preparations have been made for the process of subtracting the time used for the developer switching operations performed up to that point by the predetermined switching operation time.

As a result of the judgment in step 531, if the timer is not counting time, the process advances to step S38, and it is checked whether the trigger signal outputted when the timer finishes timing is turned on, and if it is not outputted, the process returns to the main routine. If it is being output, the switching operation of the developing device is stopped, the flags F1 and F2 are reset to O (step S39.540), and the copying operation is started (step 5=11).

〔Effect of the invention〕

As explained above, in the present invention, when a developer operation signal for selecting a desired developer from a plurality of developer units is input and a print switch is turned on, a predetermined switching operation time required for switching the developer is set. If you set this and perform a switching operation, but if you cancel the switching operation in the middle of switching and select the same developer again, the switching operation may progress, such as some developer being collected by the previous switching operation. Therefore, the switching operation is performed by setting a shorter developing device switching operation time to be restarted by an amount corresponding to that time.

As a result, switching of the developing device can be completed earlier than in the conventional system, and no time is wasted in the switching operation.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the main structure of a copying machine suitable for carrying out the present invention, FIG. 2 is an external view of the developing device, and FIGS. 3 and 4 are cross-sectional views showing the main structure of the developing device. Figure 5 is a perspective view showing the shutter part inside the developing device, Figure 6 is a front view of the operation of the copying machine, and the front view of the F channel, Figure 7 is a block diagram of the control circuit, Figures 8 and 9. 1 is a flowchart showing signal processing within a microprocessor regarding developer switching control. 1: Copying machine, 2: Photosensitive drum, 5: First developing device, 6.
Second developing device, 72: bucket, 73: shutter, 75゛ cylindrical magnet, 76: developing sleeve. Patent applicant Minolta Camera Co., Ltd. Figure 4 No. 7

Claims (1)

[Claims] A developing device that is equipped with a plurality of selectively switchable developing devices, and selects a predetermined developing device from the plurality of developing devices in the previous unit based on a developing device selection signal inputted from the outside and sets it in an operable state. In the image forming apparatus equipped with a switching control means, the developer switching control means sets a predetermined switching operation time based on an input developer selection signal, starts the developer switching operation, and starts the developer switching operation. When a switching stop signal is input during the process, the developer switching operation is stopped, and then the developer whose switching operation was stopped is reselected.When a developer selection signal is input, the switching operation is performed for a shorter time than the predetermined switching operation time. 1. A method for controlling developer switching in an image forming apparatus, comprising: setting an operation time to restart the developer switching operation; and starting an image forming operation when the switching operation time has elapsed.