JPH0362048A - Image forming device - Google Patents

Abstract

PURPOSE:To exchange a unit without making a user feel a sense of incongruity by providing a control means which changes the transferring efficiency in a transferring means when a specified value is counted by a counting means which carried out a cumulative count of the number of images formed. CONSTITUTION:The number of images formed is counted by accumulating at the counting means, when this number reaches the specified value, and transferring voltage fed to the transferring means, for example, is changed to differ from a former transferring efficiency and carrying out image formation. Therefore, if the specified value is set responding to unit exchanging period, for example, when it becomes the unit exchanging period, deterioration can be generated in the image quality of the formed image. Thus, the user can respond to unit exchange without feeling the sense of incongruity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention (Industrial Application Field) The present invention relates to an image forming apparatus used in, for example, a laser printer, a digital copying machine, and the like.

(Prior Art) Conventionally, image formation in an image forming apparatus such as a laser printer is performed through various steps such as charging, exposure, development, transfer, peeling, cleaning, and fixing. In such an image forming apparatus, a charging device, an exposure device, a developing device, a transfer device, a peeling device, a cleaning device, etc. are sequentially arranged around the photoconductor, and a fixing device is further provided to receive the paper from the peeling device. By driving each of the devices described above in accordance with the rotational movement of the photoreceptor, each of the image forming steps described above is executed to form an image.

By the way, the photoreceptor, the developing device, the fixing device, etc. are so-called consumables that wear out with use.

Therefore, a replacement period (life span) is determined depending on the number of times of use, and replacement is required when the number of times of use reaches a predetermined value. In order to facilitate such replacement work, a unit structure is adopted in which a plurality of the above devices are integrated. For example, a photoconductor, charging device, exposure device, developing device, transfer device, peeling device, cleaning device, etc. are integrally constructed as a process unit, and a fixing device and its accessories are integrally constructed as a fixing device unit. has been done. By adopting such a unit structure, adjustment work performed when replacing the device becomes extremely simple, and maintenance work can be performed efficiently.

Such an image forming apparatus requires unit life management, which is performed as follows. In other words, the lifespan set for the unit is converted into the number of copies of paper of a predetermined size and stored in a non-volatile memory installed inside the device, and when the contents of this memory become zero, the unit is A message indicating that the unit should be replaced is displayed, and printing operations are not possible until the unit is replaced with a new unit.

However, in reality, there are cases in which printing can be performed with good image quality even after the time for replacing the unit has passed, and even in such cases, printing cannot be performed unless the unit is replaced with a new unit, so the user is not satisfied. The disadvantage was that the unit had to be replaced before it could be completed.

(Problems to be Solved by the Invention) As described above, the present invention is capable of printing with good image quality even after the time for replacing the unit has passed, and even in such cases, it is possible to replace the unit with a new one. This was done in order to eliminate the drawback that the user had to replace the unit without being satisfied with the printing operation because the printing operation could not be performed unless the user was satisfied with the image formation. The purpose is to provide equipment.

[Configuration of the Invention (Means for Solving the Problem) The image forming apparatus of the present invention includes a photoreceptor, a charging means for uniformly charging the photoreceptor, and a photosensitive member uniformly charged by the charging means. an exposure means for exposing a photoreceptor according to an image; a developing means for developing an electrostatic latent image formed on the photoreceptor by exposure of the exposure means; and a developer image obtained by the development of the developing means. In an image forming apparatus comprising a transfer means for transferring a developer image onto a transfer material, and a fixing means for fixing the transfer material to which a developer image has been transferred by the transfer means, a counter for cumulatively counting the number of images formed. The present invention is characterized in that it comprises a control means for changing the transfer efficiency of the transfer means when the counting means counts a predetermined value.

(Function) The present invention accumulates and counts the number of images formed by a counting means, and when this number reaches a predetermined value, changes the transfer voltage supplied to the transfer means to improve the transfer efficiency compared to the previous one. The image is formed by making the image different from the image.

By setting the predetermined value in accordance with, for example, the time to replace the unit, it is possible to cause deterioration in the image quality of the image formed when the time comes to replace the unit, making the user feel uncomfortable. The unit can be replaced without any problems.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 2 shows the external appearance of an electronic photorealistic image forming apparatus using a semiconductor laser, and FIG. 3 shows its internal configuration. This image forming device (laser printer) is connected to a host system (external device such as a computer or word processor).
(not shown) via a transmission controller such as an interface circuit. When receiving a print start signal from an external device, the image recording operation is started, and the image is recorded on paper as a transfer material and output.

This image forming apparatus has the following configuration. That is, numeral 1 in the figure is a main body of the apparatus, and a main control board 2 is disposed in the center of the main body 1, as shown in FIG. An electrophotographic process unit 3 for forming images is arranged behind the main control board 2 (to the right in the state shown in Fig. 3), and a plurality of function-adding controls are arranged at the lower front. A control board accommodating section 5 for accommodating a plurality of boards 4 is also provided with a paper discharge section 6 formed at the upper front thereof.

Up to three of the above control boards 4 for adding functions can be installed depending on the functions to be added (for example, adding types of fonts, 7! A characters, etc.). By inserting function-adding IC cards 17 into three IC card connectors 16 arranged on the front edge of the control board 4, other functions can be added. Furthermore, two interface connectors (not shown) are arranged on the left end surface of the function addition control board 4 located at the bottom, and these interface connectors are connected to the device main body 1.
It is exposed through an opening 18 (see FIG. 2) formed on the left side of the.

Further, a lower portion inside the apparatus main body 1 is a cassette accommodating section 8 that accommodates a paper feed cassette 7.

As shown in FIG. 2, the paper discharge section 6 consists of a recess formed on the front upper surface of the apparatus main body 1, and the front edge of the paper discharge section 6 is folded over the paper discharge section 6, A rotatable paper discharge tray 9 that can be unfolded as shown in FIG. This paper output tray 9
A notch 9a is formed in the center of the front end of the paper sheet, and the size of the rotatable U-shaped paper discharge section 6 that can be accommodated in the notch 9a or unfolded as shown in FIG. 3 can be adjusted. It looks like this. Further, on the upper surface of the left frame portion 1a of the main body of the apparatus located on the left side of the paper ejection portion 6, a display LED II is provided.
, a 7-segment display 12 for two-digit status display, and a control panel 14 with switches 13 are arranged, and a manual feed tray 15 is attached to the rear side of the main body 1 of the apparatus. There is.

Next, charging, exposure, development, transfer, peeling, cleaning, and fixing are performed.
The electrophotographic process unit 3 that performs electrophotographic processes such as electrophotography will be described with reference to FIGS. 3 and 4.

A drum-shaped photoreceptor 20 serving as an image carrier is disposed approximately in the center of the unit accommodating portion, and this photoreceptor 20
Around the , along the direction of rotation (direction of the arrow in the figure), there is a scorotron charger 21, an exposure section 22a1 of a laser exposure unit 22 as an exposure means for forming an electrostatic latent image, a developing process and a cleaning process. A magnetic brush type developing device 23 that simultaneously performs the above steps, a transfer charger 24 made of a scorotron, a memory removal brush 25 made of a brush member, and a pre-exposure lamp 26 are arranged in this order to constitute the process unit 3.

Also, inside the apparatus main body 1, paper P fed from the paper cassette 7 via the paper feeding means 27 and paper P manually fed from the manual tray 15 are transferred between the photoreceptor 20 and the transfer charger 24. A paper conveyance path 29 is formed which leads to a paper discharge section 6 provided on the upper surface side of the apparatus main body 1 via an image transfer section 28 between the two.

A pair of transport rollers 30. A pair of aligning rollers 31 and a pair of conveying rollers 32 are arranged, and a fixing unit 3 is arranged on the downstream side.
3 and a paper discharge roller unit 34 are arranged. Further, a cooling fan unit 35 is disposed above the location where the pair of conveyance rollers 32 are disposed.

Note that an aligning switch 36 is provided near the aligning roller pair 31, and an aligning switch 36 is provided near the aligning roller pair 31.
A conveyance guide 37 is provided near 8.

When a print start signal is received from the external device 401, the drum-shaped photoreceptor 20 rotates, and the photoreceptor 20 is charged by the charger 21.

Next, the laser beam a modulated in response to the dot image data from the external device 401 is transmitted to the laser exposure unit 22.
is used to perform scanning exposure on the photoreceptor 20 to form an electrostatic latent image on the photoreceptor 20 corresponding to the image signal. This electrostatic latent image on the photoreceptor 20 is developed by the toner t in the developer magnetic brush D' of the developing device 23, and is visualized to obtain a toner image.

Meanwhile, in synchronization with this toner image forming operation, the paper P taken out from the paper feed cassette 7 or manually fed from the manual feed tray l5 is sent to the image transfer section 28 via the aligning roller pair 31, and is fed to the photoreceptor. The toner image formed on the paper P is transferred to the paper P by the action of the transfer charger 24.
transcribed into. Next, the paper P passes through the paper transport path 29 and is sent to the fixing device unit 33, where the toner image is melted and fixed onto the paper P. After this, the paper ejection roller unit 3
4 and is discharged to the paper discharge section 6.

Note that after the toner image is transferred onto the paper P, the residual toner remaining on the photoreceptor 20 is removed by a memory removal brush 25 made of a conductive brush, thereby performing memory removal.

Further, as shown in FIG. 4, the fixing device unit 33 includes a heat roller 41 having a built-in heater lamp 40, and a pressure roller 42 that is in pressure contact with the heat roller 41. , 42, the toner image is fused and fixed on the paper P.

Further, the heat roller 41 and the pressure roller 42 are surrounded by a lower casing 43 and an upper casing 44, and are structured to prevent heat from escaping to the outside as much as possible to ensure a favorable temperature atmosphere necessary for fixing. ing.

A cleaner 45 is in contact with the heat roller 41, and the temperature is controlled by a thermistor 46 to maintain the temperature necessary for fixing. The structure is such that

Further, a paper guide 48 is disposed near the upstream side of the contact portion 47 between the heat roller 41 and the pressure roller 42 in the upper casing 44 to ensure that the leading edge of the paper P guided to the fixing unit 33 is heated. It is designed to be guided between the roller 41 and the pressure roller 42. A paper guide 49 is provided integrally with the lower casing 43 on the paper exit side of the fixing unit 33 and guides the paper P in the fixing unit to the paper discharge roller unit 34.

Further, the above-mentioned transport guide 37, which is disposed on the transport direction side of the transfer charger 24 and guides the non-image side of the paper P, is in a grounded state and functions to electrostatically attract and float the paper P. do.

Further, the paper ejection roller unit 34 includes a lower roller 50.
and an upper roller 51, and the paper P is
A static eliminating brush 52 is provided in contact with the non-image forming surface of the image forming apparatus. Upper roller 51 and static elimination brush 5
The upper half including the transport guide 37. The transfer charger 24 and the like are attached to the lower surface of the top cover of the main body 1 of the apparatus.

Further, as shown in FIG. 4, the laser exposure unit 2
2 is a semiconductor laser oscillator 90 (not shown in detail), a polygon scanner 93 consisting of a polygon mirror 91 and a mirror motor 92, a second lens 95 for fo, a second lens 95 for fθ, and a predetermined scanned laser beam a. It is composed of reflecting mirrors 96, 97, etc. for scanning to the position.

Further, the control board 101 of this laser exposure unit 22 is connected to the main control board 2 via a connector 102.

Furthermore, the laser exposure unit 22 is housed in a synthetic resin casing 103 that is open at the bottom, and the bottom opening of the casing 103 is connected to a metal shield plate 104.
At the same time, the casing 1
A shield cover 105 made of metal and also serving as a reinforcing plate is superimposed on the upper surface side of 03. A conductive contact piece 106 is connected to the shield cover 105.
When the laser exposure unit 22 is attached to a predetermined position via an attachment means (not shown), this contact piece 106 comes into contact with a metal guide rail that slidably guides the developing device 23, and the contact piece 106 comes into contact with a metal guide rail that slidably guides the developing device 23. This prevents malfunctions caused by the negative effects of static electricity on the inside.

Note that the photoreceptor 20 uses an organic photoconductor,
It has a structure in which a charge generation layer and a charge transport layer covering this charge generation layer are formed on the surface of an aluminum cylinder.

Further, in order to simplify the electrophotographic process, the developing device 23 employs a reversal developing method and also employs a method in which the residual toner t after transfer is removed at the same time as the developing. As shown in FIG. 4, this developing device 23 includes a photoreceptor 20 and a casing 121 having a developer storage section 120.
A developing roller 122 is provided opposite to the developing roller 122, and a toner (colored powder) t is provided in the developer storage section 120.
A two-component developer consisting of a carrier (magnetic powder) C and a carrier (magnetic powder) is contained therein. Further, a developer magnetic brush D' formed on the surface of the developing roller 122 is provided at a sliding contact portion with the photoreceptor 20, that is, on an upstream side in the rotational direction of the photoreceptor 20 than the development position 123. A doctor 124 is provided to regulate the thickness of '. Further, the developer storage section 120 includes a first. Second developer stirring body 12
5,126 are accommodated. Note that the developing device 23 is equipped with a toner cartridge (not shown) as a toner replenishing device, and is adapted to appropriately replenish the developer storage portion 120 with toner t.

Further, the developing roller 122 has three magnetic pole parts 127.12.
8, 129, and a non-magnetic sleeve 131 that is fitted onto the magnetic roll 130 and rotates clockwise in the figure. magnetic roll 130
Of the three magnetic pole parts 127, 128, 129, the magnetic pole part 128 facing the development position 123 is the north pole, and the other magnetic pole parts 127, 129 are the south pole.

Further, the angle e1 between the magnetic pole part 127 and the magnetic pole part 128 is 150'', and the angle e between the magnetic pole part 128 and the magnetic pole part 129 is 150''.
2 is set to 1206. The electrostatic charge on the photoreceptor 20 is caused by the potential difference between the mechanical scraping force caused by the magnetic brush development using the two-component developer, the charging potential caused by the reversal development, and the development bias applied to the magnetic brush D'. At the same time as the latent image is developed, residual toner t is collected mechanically and electrically.

Furthermore, this developing device 23 includes a photoconductor 20° charger 21. The memory removal brush 25 and the like are integrated into a process cartridge 85, and the process cartridge 85 can be taken in and out of the apparatus main body 1.

Further, a cleaning brush 144 for cleaning the lower roller 31a of the aligning roller pair 31 is attached to the upper surface of the process cartridge 85.

Next, the control system of the main image forming apparatus will be explained with reference to the block diagram shown in FIG. In the figure, 401 is an external device that is connected via the aforementioned interface connector. As this external device 401,
Electronic computers, word processors, image processing devices, etc. are connected. This external device 401 is electrically connected to the control circuit 402 of this device via a video interface.

The signals shown in FIG. 5 are prepared as signals for this video interface. In other words, the IVCLKO signal is an image clock (video clock) signal output from the main device 1 to the external device 401, and the external device 401 outputs video data IVD in synchronization with this image clock signal.
Output ATO. The IH8YNO signal is a horizontal synchronization signal that is output from the main device 1 to the external device 401 prior to transferring one scan's worth of image data.

The IDAT71-01 signals are bidirectional 8-bit data buses that receive commands from the external device 401 via this bus, and output statuses indicating the state of the main device 1 to the external device 401. Further, the external device 401 is capable of transmitting a status request command for knowing the status of the main device 1 at any time.

The ID5TAO signal is a signal that determines the direction of data transfer on the 8-bit data bus, and the 15TBO signal is a strobe signal for the main unit 1 to receive commands, both of which are output from the external device 401.

The IBSYO signal is a busy signal indicating that the main body device 1 is processing a command from the external device 401.

The IATNI signal is an attention signal output by the main device 1 when a situation that the external device 401 should immediately know about occurs in the main device 1.

The IPRDYO signal is a signal indicating that the main unit 1 is in a ready state. IPRIMEO signal is external device 4
01 is a reset signal output to the main device 1. l5
The CLRI signal is a clear signal that the main unit 1 outputs to the external device 401 when the main unit 1 is powered on and off.

The control circuit 402 shown in FIG. 1 includes a microcomputer (hereinafter referred to as rcPUJ), R
AM402a, ROM consisting of erasable FROM
A402bS It is composed of ROMB4O2c, etc., which is composed of an electrically erasable FROM, and the CPU processes seed data and performs various controls. The RAM 402a is used to temporarily store image data to be processed by the CPU, or to store various data required when the CPU operates. ROMA402b mainly uses CPU
It stores the program that runs the . Also,
ROMB4O2c is designed to store, for example, the cumulative number of printed sheets, etc., by taking advantage of the characteristics that the contents do not disappear even when the power is turned off and can be rewritten (details will be described later). .

This control circuit 402 includes a driver circuit 403.
Through the cooling fan unit 35, various solenoids 40
4. A main motor 405 and various switches 406 are connected. In addition to the laser exposure unit 22 and control panel 14 described above, it also controls the high voltage power supply 407,
Alternatively, a signal from the cassette size switch 408 is input. In addition, the main switch 41
0, 100V AC power is supplied to the AC power supply device 411, and from the output of this AC power supply device 411, DC power of the required voltage is generated in the DC power supply device 412, which is used in the control circuit 402 and other circuits. It is designed to be supplied to In addition, the fuser unit 3
3 is supplied with the output of an AC power supply device 411.

The main functions of the control circuit 402 are listed as follows:
It is as follows. (1) Video ink - decodes information from the face, that is, commands from the external device 401, and controls each part of the device according to the instructions. Further, the status corresponding to the command is output to the external device 401 via the video interface. Also IATNI
Controls the output of the signal, IPRDYO signal, and l5CLRI signal. (2) LED of control panel 14
The display contents are output to the 7-segment display 12. (3) The various solenoids 404 are controlled to turn on or off. (4) Various switches 406
Ingest and process information from.

(5) On/off control of the mirror motor 92 and power setting and power monitoring of laser emission are performed.

(6) Process toner concentration information from the toner concentration sensor. (7) Control the high voltage power supply 407. That is, output on/off control and output power setting for the charging charger 21, output on/off control and output power setting for the transfer charger 24, output on/off control and output power setting for the developing bias, and memory removal brush 25 Performs output on/off control and output power settings, etc. It also monitors whether each output is operating normally. (8) On/off control of the main motor 405 and monitoring of steady rotation are performed.

(9> Turn on/off the fan motor of the cooling fan unit 35
Off control is being performed. (10) Pre-exposure lamp 26
On/off control is performed. (1) The temperature of the heat roller 41 of the fixing unit 33 is monitored, and the heater lamp 40 is controlled on and off.

As briefly explained above, the control circuit 402
corresponds to the command unit of the main unit 1 and performs various controls.

Next, the operation of the above configuration will be explained with reference to the flowchart of FIG. 6 and the timing chart of FIG. 7.

First, when the main switch 410 of the image forming apparatus is turned on to supply power to the AC power supply device 411, +5V of the DC power supply device 412 is turned on.

At this time, a reset signal is generated by a reset signal generation circuit (not shown), and the CPU of the control circuit 402 is reset. Next, an initialization operation is performed. In other words,
In addition to initializing various circuits, data of the RAM 402a, I10 port (not shown), interface between external devices, etc. is initialized (step Sl). Next, an error check accompanying the initialization is performed (steps Sl and S2). The error check in this initialization operation is to check whether or not the cause of the operator call shown in FIG. 8 and the cause of the service call shown in FIG. 9 have occurred.

In FIG. 8, "Operator call (1)" is an operator call that occurs during initialization, "Operator call (2)" is an operator call that occurs during warming up after initialization, and "Operator call ( 3
)” is the print order waiting letter 7! ! An "operator call (4)" that occurs during (standby) is an operator call that occurs during printing operation. The "○" mark in the figure indicates the cause of the operator call check, and means that if an operator call occurs, the code will blink on the 7-segment display 12 on the control panel 14. .

Further, a "-" mark indicates a reason why an operator call check is not being performed, and means that even if an operator call occurs, the code will not be displayed. Additionally, if duplicate operator calls occur, the corresponding codes will be displayed blinking in sequence. Furthermore, if the cause of the operator call is removed, the code blinking will be canceled. Note that when "01 to 03" marked with "*" are lit up, the device is ready for use.

In Figure 8, "Service call (1)" is a service call that occurs during initialization operation, and "Service call (2)" is a service call that occurs during initialization operation.
)" is a service call that occurs during warming up after initialization, "Service call (3)" is a service call that occurs while waiting for a print command (standby), and "Service call (4)" is during print operation. This is a service call that occurs. And "○ mark" in the diagram
indicates the cause of the service call check, and means that if a service call occurs, the code will blink on the 7-segment display 12 on the control panel 14, and the "-" mark indicates the cause of the service call. This means that no check has been performed. Furthermore, after turning off the power, remove the cause of the service call, and then turning on the power again to cancel the service call.

When the error check in the above initialization operation is completed,
The heating of the fixing device 33 is started (step S4), and a warming-up operation is started. The temperature control of this fixing device 33 is as follows:
This is performed by a subroutine that is called every 30m5ec in the main routine. Note that this temperature control of the fixing device 33 is continued not only during warming up, but also during standby and printing.

During this warming up, the mirror motor 92 and main motor 405 are rotated (steps S5 and S6),
A mirror motor rotation check, a main motor rotation check, a laser emission check, an H8YNC detection check are performed, and in order to initialize the process control, the pre-exposure lamp 26, charger 21, memory removal brush 25, and developing device (not shown) are checked. Turn bias on/off sequentially. At this time, the attachment of the transfer charger 24 is checked by turning on the transfer output to the transfer charger 24 for a short time at the same time that the attachment of the charger 21 is checked.

In this state, when it is determined that the temperature of the fixing device 33 has reached the specified temperature and the warm-up has been completed without any service call or operator call (step S9), the main unit 1 becomes ready, and stops the mirror motor 92 and main motor 405 (step 5IO). Then, the ready signal I P
RDYO, an attention signal IATNI, and a print request signal as the status of the main device 1 are output (step 511). Then, the main device 1 enters a print command waiting state and waits for a print command to be issued while performing an error check (steps 812 to 812).
514).

On the other hand, the external device 401 receives the ready signal I PRDY.
O, receives the attention signal IATNI and the print request signal, resets the IATENI signal by transmitting an attention reset command, and reads the status of the main device (here, that it is in a printable state).

In this state, the external device 401 sends a print command to the main device 1, and the main device 1 starts a printing operation upon receiving this print command.

That is, when it is determined that a print command has been received (step 514), first, it is checked whether the process unit 3 or the fixing device unit 33 is past the replacement period (step 5TI). This replacement period is for ROM
B4O2c DVCO/DVCI area or FXCO/
The determination is made by referring to the contents of the FXC1 area (see FIG. 10). When it is determined that the replacement time has passed, a predetermined analog signal is supplied to the high voltage power supply 407 in order to reduce the transfer voltage according to the number of sheets printed after the replacement time has passed (step 5T2). . In the subsequent transfer operation, the toner image formed on the photoreceptor 20 is transferred to the paper P by supplying the transfer charger 24 with a transfer voltage corresponding to this analog voltage.

Next, the control temperature of the fixing device 33 is increased (step 51).
5). This is because the temperature of the fuser 33 is set to a lower temperature in the standby state than during the fixing operation, so the heater lamp 40 is forcibly turned on so that the fixing temperature is quickly reached at the same time as the printing operation starts. and set the control temperature high.

Next, the mirror motor 92 is rotated as shown in FIG. 7(j) (step 516), and then as shown in FIG. 7(a).
The main motor 405 is rotated as shown in (step 517). Furthermore, as shown in FIG. 7(b), the paper feed solenoid (not shown) is turned on for a predetermined period of time (step 5).
18). When this paper feed solenoid is turned on for a predetermined period of time, the half-moon-shaped paper feed roller 27 rotates once, and the paper P
is taken out from the paper feed cassette 7 and transported to the transport roller pair 32. With the start of transport of the paper P, as shown in Fig. 7 (
As shown in m), the status of main unit 1 indicates that paper is being transported.

When feeding paper from the paper feed cassette 7, the pair of transport rollers 32 is constantly rotating, and the paper is transported to the aligning roller 31 via the aligning switch 36. At this time, the CPU
checks whether or not the aligning switch 36 detects the paper P within a certain specified time after operating the paper feed solenoid (step 519), and if the paper P is not detected, it is treated as a paper feed section jam. (Step 541) The conveying speed during paper feeding is made faster than the conveying speed of the pair of conveying rollers 32 onwards, thereby stabilizing the paper feeding performance.

Now, when the paper P reaches the aligning roller 31, the aligning roller 31 has stopped, and the transport roller 32 further transports the paper P.

At this time, when the leading edge of the paper P comes into contact with the aligning roller 31, the transport roller 32 slips, and the paper P is controlled so as not to bend. On the other hand, in parallel with the conveyance of the paper P, as shown in FIG.
20).

After this, when a VSYNC command signal is received within 10 seconds (step 521), as shown in FIG. 7(C),
An aligning solenoid (not shown) is turned on, thereby causing the aligning roller 31 to rotate and the paper P to be conveyed to the photosensitive drum 20. On the other hand, within 10 seconds VSY
If the NC command signal is not received, it is processed as a VSYNC error service call (4) (step 542).

On the other hand, on the interface, upon reception of the VSYNC command, main unit 1 outputs a horizontal synchronization signal IH, which is a periodic pulse.
Sends SYNCO and image clock IVCLKO.

Since the external device 401 sends out image data IVDATO in synchronization with these signals, the main device 1 receives this image data IVDATO (step 522).
.

This image data IVDATO is stored in the control circuit 4.
02 to the laser unit driver 22a of the laser exposure unit 22, and is used as a signal to drive the semiconductor laser oscillator 90.

As a result, laser exposure is started as shown in FIG. 7(f). That is, the laser unit driver 22a modulates the laser beam by turning off/on the semiconductor laser oscillator 90 according to the signal level of the image data IVDATO. The modulated laser beam is corrected into parallel light by a collimator lens (not shown) and is incident on a polygon mirror 91. The polygon mirror 91 is directly driven by a mirror motor 92 and rotates at a constant speed. The laser beam reflected by this polygon mirror 91 passes through a second lens 95 for fθ, a reflecting mirror 96,
The light is focused onto the photoreceptor 20 via the reflection mirror 97 and the second fθ lens 95, and the beam spot scans the photoreceptor 20 at a constant speed.

At this time, H3YN (not shown) detects the position of the laser beam.
This is done using a C detection mirror. The laser beam reflected by the H5YNC detection mirror is incident on a pin diode (not shown) to generate a horizontal synchronization signal IHSYNCO. During this time, the main device 1 displays the status of data transfer as shown in FIG. 7(n).

Note that in parallel with the above operation, the photosensitive drum 20 is rotating as the paper P is transported, and as shown in FIG. As shown in Figure (g), the charging charger 21 is turned on and the surface of the photoreceptor 20 is uniformly charged. Charging is performed by corona discharging the output of the high-voltage power supply 407 using a scorotron charger, and the battery is charged to a negative potential.

Next, scanning exposure is performed using the laser beam, and an electrostatic latent image corresponding to the image data is formed on the photosensitive drum 20. This electrostatic latent image on the photosensitive drum 20 is transferred to a developing device 23.
The image is developed by the toner t in the magnetic brush D' and visualized.

On the other hand, the conveyed paper P is conveyed onto the photosensitive drum 20 by turning on the aligning solenoid (step 523), causing the aligning roller 31 to rotate. Then, the toner image formed on the photosensitive drum 20 is transferred onto the paper P by the action of the transfer charger 24 being turned on as shown in FIG. 7(d).

Next, the paper P passes through the paper transport path 29 and is sent to the fixing unit 33. This fixing device unit 33 is
It includes a heat roller 41 containing a heater lamp 40 and a pressure roller 42 pressed by the heat roller 41, and the toner image is fused and fixed by passing between these rollers 4142. Then, the paper passes through a paper ejection switch (not shown), reaches the paper ejection roller unit 34, and is ejected to the paper ejection section 6. Here again, the CPU checks whether the paper ejection switch detects the paper P within a certain specified time after operating the aligning roller 31 (step 524).
If the paper ejection switch does not detect the paper P at this time, it is treated as a paper ejection section jam (step 543).
). Note that after the toner image is transferred onto the paper P, the toner remaining on the photosensitive drum 2° is removed by a memory removal brush 25 made of a conductive brush, memory removal is performed, and the toner is collected during the next development process. It turns out.

Furthermore, an error check is performed during the printing operation, that is, until the end of image data transfer (step S2).
5.526) When an error occurs, service call (4) and operator call (4) are processed depending on the cause of the error. - On the other hand, when the image transfer is completed without any error (step 527), the image transfer end processing is performed (step 528).In other words, an attention signal is output, an IH3YNC signal, an IVCL
The output of the KO signal is ended, and the reception of the IVDATO signal is also ended. Furthermore, the status during data transfer shown in FIG. 7(n) is also reset.

Next, the aligning solenoid is turned off to stop the aligning roller 31 (step 529). Then, it is determined whether or not the paper discharge switch detects the paper P at a certain specified time after the aligning roller 31 stops operating (step 530). If the paper ejection switch does not detect the paper P at this time, it is treated as a paper ejection section jam (step 544). Meanwhile, the paper ejection switch is turned off.
That is, when it is determined that the paper discharge switch has detected the paper P (step 530), the mirror motor 92 and the main motor 405 are stopped (step 531), and the control temperature of the fixing device 33 is lowered (step 532). . As a result, the fixing device 33 returns to its original standby state and finishes printing one sheet.

If printing is to be continued, the process returns to step S12 and the same operation is repeated.

Note that the timing chart shown in FIG. 7 shows a case where A4 size paper P is stored in the paper feed cassette 7 and two sheets are successively printed by horizontal feeding.

FIG. 6(d) shows steps S41 and 34B.

The processing performed in S44 when a paper jam occurs is shown. That is, when a paper jam occurs, the error state is cleared by opening the cover (step 545) and then closing the cover (step 546).

In reality, the operator opens the cover, removes the jammed paper P, and then closes the cover. Then, when the error state is cleared, the process returns to step S2, and the series of processes described above except for the initialization process (step S1) are performed.

In this device, the size of the printing area and jam detection are performed depending on the size of the paper P used.

That is, the paper P stored in the paper feed cassette 7 is separated from the cassette size switch 408 (the first
(see figure) is turned on, various paper sizes are detected.

In addition, in order to manage the usage status of the main unit 1, the number of printed sheets P is counted in a non-volatile memory. At this time, as a counting standard, A4 size horizontal feed (210 m
m) is set as "1", and each sheet P is counted relative to 210 mm.

For example, in the case of A3 size, the length in the transport direction is 420 m.
m, the converted value is "2".

In this embodiment, a ROMB4O2c composed of an electrically erasable FROM is used as the counter for the number of printed sheets.

FIG. 10 shows the allocation of ROMB4O2c. To count the paper P, the time during which the aligning roller 31 is rotating is accumulated inside the RAM 402a, and when it rotates by the A4 horizontal size, the counting area TOTALC in the ROMB4O2C is set to r+IJL, and every time TOTALC is +50 , PRC3CO/PRC3CI, DVCO/
Each area of DVCI and FXCO/FXCI is incremented by "+1". In other words, the TOTALC stores the total number of printed sheets converted to A4 horizontal size, and the values obtained by converting this value into a 50-decimal number are used as the total count, process unit life count, and fuser life count, respectively on the PRC3CO/P
RC5CI, DVCO/DVCI, FXCO/FXCI
stored in the area. With this counting method, when the process unit 3 or the fixing device 33 reaches a predetermined value, C
Each PU is determined to be at the end of its life, displays a message to that effect, and indicates the end of life on the interface status. New process unit 3 installed and toner sensor normalization completed Shitatoki, DVCO/DVC
The I area is cleared to "o" and printing becomes possible again, and at the same time the process unit 3 starts counting from rOJ.

Further, FXCO/FXCI is cleared to "0" when the fixing device 33 is replaced with a new fixing device 33. Also, ROM8402C
(7) Each area is guaranteed to rewrite data only up to 10,000 times, whereas the lifespan of each unit is 30
A large amount such as 10,000 or 500,000, TOT A L
C+: When the count reaches 110,000, the next address is incremented by "+1" from "0", and thereafter the address is sequentially updated every 10,000 counts. That is, one storage area is abandoned every 10,000 counts. Therefore, it is necessary to manage the current address, and for this reason BANKOO
The current address is held in /BANKO1 and used as an address pointer. Also, if an unwritable area occurs during the process, the counting area is moved to the area indicated by the next address. However, when calculating the total count later, B
This is done by referring to the contents of ANK○0/BANKO1, so
If no action is taken, a maximum of 1
The count will increase by 0000. Therefore,
The number of defective areas is stored in BANK10/BANKII and used for correction when calculating the total count later.

However, in the above method, when printing one page immediately after turning on the power, when the paper P1 is smaller than A4 horizontal size, for example, B5 size paper P, TOTALC is "+1".
It will not be done. Therefore, when printing the first sheet immediately after the power is turned on, "+1" is always added when the sheet P passes, even if the sheet P is smaller in size than A4 horizontal size.

Furthermore, if the power is kept on at this time, the sizes of the second and subsequent sheets of paper P are counted in the RAM 402a, so that the counting error can be corrected.

The ROM B 302c is used as the counting area described above, and also stores top/left margins, initial values of the toner sensor, etc.

Next, toner density control of this apparatus will be explained.

The main device 1 uses a toner concentration detection sensor 500 to
The reflected light from the probe 20a provided on the side of the photoreceptor drum 20 is detected, and based on this reflected light, the new process unit 3 is detected, the toner concentration, etc. are detected, and toner is replenished as necessary. It is supposed to be done. It also determines whether the toner is empty.

The toner density control system is configured as shown in FIG. 11, and is realized by, for example, the processing shown in the flowchart of FIG. 12. The probe 20a provided on the side of the photoconductor 20 is powered by a temporary spring (not shown) from the process unit 3 so as to have a certain potential.
Normally, toner in proportion to the toner concentration within the process unit 3 is attached to the probe 20a. Light emitting diode 501 and photodiode 502
The toner concentration detection sensor 500 configured by the above outputs a toner concentration signal proportional to the reflected light from the probe 20a to the CPU of the control circuit 402. The CPU is
When it is determined that toner replenishment is necessary based on this toner concentration signal and the toner concentration control target value, toner replenishment solenoid 503 is operated to replenish toner from toner hopper 504.

Note that if the toner density does not increase even after toner replenishment, the main body device 1 temporarily stops the printing operation and only performs the toner replenishment operation. If the toner density becomes high, printing becomes possible, but if not, the toner is treated as empty.

Therefore, toner density control has four control levels.

First, there is a toner density control target value, and based on this, a control permissible level, an empty level, and a limit level are determined in stages (for example, if each of the above control levels is
7%, +13%, +25%, etc.). When the detected value by the toner concentration detection sensor 500 is within the control permissible level with respect to the control target value, sampling is performed periodically. Sensor detection values are always compared twice, and toner is replenished only when the newly detected value is larger.

Further, when the sensor detection value is smaller than the control target value, replenishment is not always performed. However, when the control tolerance level is exceeded, toner is always replenished, and when the empty level is exceeded, the toner is treated as empty. Furthermore, the amount of replenishment is not constant, but is changed in stages according to the amount of change in the sensor detection value.

Since the process unit 3 of this apparatus is removable, it is determined whether the process unit 3 is old or new when the power is turned on and when the cover is opened or closed. The auto toner probe 20a of the new process unit 3 is wrapped with black tape for detecting new and old. Therefore, when the new process unit 3 is installed, the output of the toner concentration detection sensor 500 is small. The main motor 405 rotates, and the probe 2
When the black tape wound around 0a is wound up, the output of the toner concentration detection sensor 500 suddenly increases.

Here, after turning on the main motor 405, the low level 0.4 V or less continues for 0.4 seconds or more, and then the high level 1
．． When the voltage of 5V or more continues for 064 seconds or more, it is determined that the new process unit 3 has been installed. When the CPU determines that the installed process unit 3 is new, it enters aging for 3 minutes. After this aging, when the amount of adhesion to the probe 20a becomes stable, the CPU stores the output of the toner concentration detection sensor 500 in the ROM as the toner concentration control target value.
Store in the TNS IO/TNS 11 area of B4O2c. In other words, the toner concentration control target value is always rewritten every time the process unit 3 is new. If the output value of the toner concentration detection sensor 500 at the end of 3 minutes of aging is abnormally large or small, the new process unit 3 is treated as defective, a service call (2) is displayed, and the external device The status is sent to 401.

Although the case of cassette paper feeding in which paper is fed from the paper cassette 7 has been described above, the case of manual paper feeding is basically the same. Printing by manual paper feeding starts when the main body device 1 receives a manual paper feeding command from the external device 401. When the manual paper feed command is received, the main body device 1 detects whether or not paper P is inserted into the manual paper feed tray 15 using a manual feed switch (not shown). If the paper P cannot be detected, operator calls (2) and (3) are displayed on the control panel 14 to notify the operator that there is no manual feed paper. When the paper P is inserted into the manual feed tray 15 and the paper P is detected by the manual feed switch, the mirror motor 92 and the main motor 405 are rotated, the paper P is transported by the transport roller 32 to the aligning roller 31, and then the paper P is transported to the outside. A print command from the device 401 is awaited. If the paper P is pulled out by the operator before the print command is accepted, the operator calls (2) and (3) are displayed again. When the paper P reaches the aligning roller 31, a print command and a VSYNC command are received from the external device 401, and when image data transfer begins, the aligning solenoid is turned on to rotate the aligning roller 31 and remove the paper. P is conveyed to the photoreceptor drum 20. Thereafter, the printing process, jam detection, etc. are performed in the same manner as for feeding paper from the paper feeding cassette 7 shown in FIG. However, regarding the paper size, a command for each paper size is received from the external device 401, and control such as counting the number of printed sheets is performed based on this data.

FIG. 13 is a partial block diagram of a control section that controls the transfer voltage applied to the transfer charger 24.

The control signal TRCHO in the figure is a transfer on/off signal, and when the TRCHO signal becomes active, the transfer voltage applied to the transfer charger 24 can be changed by an analog signal output from the control circuit 402. It has become.

Then, as explained in Fig. 6, it is checked whether the unit has passed the replacement time or not, and if the replacement time has passed, the process of lowering the transfer voltage according to the number of sheets printed from that point on is performed. It will be done.

As a result, as the number of printed sheets increases, the transfer efficiency decreases, and as shown in FIG. 14, the image quality gradually changes.

In other words, when the replacement period has passed, normal printing is possible as shown in ■ in the same figure, but as the number of sheets printed increases, the image quality gradually deteriorates as shown in ■, ■, and ■ in the same figure. The operator can easily accept that the unit should be replaced.

As explained above, in the above embodiment, the number of prints is cumulatively counted in ROMB4O2C, which is a non-volatile memory, and when this counted value reaches a predetermined value, the transfer voltage is supplied to the transfer charger 24, for example. By changing the transfer efficiency, printing is performed with a different transfer efficiency than before, so by setting the above predetermined value in accordance with, for example, the unit replacement time, when the unit replacement time has passed, printing will be performed after that time. Since this can cause deterioration in the image quality of the image, the user can replace the unit without feeling uncomfortable.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide an image forming apparatus in which the user can replace the unit without feeling uncomfortable.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is a block diagram showing the configuration of the overall control system, Fig. 2 is an external perspective view of the image forming apparatus, and Fig. 3 is a vertical side view, 4 is a partial vertical side view, FIG. 5 is a diagram for explaining video interface signals, FIG. 6 is a flowchart for explaining the operation, and FIG. 7 is a timing chart for explaining the operation. Figure 8 is a diagram for explaining the causes of operator calls, Figure 9 is a diagram for explaining the causes of service call, Figure 10 is a diagram for explaining ROMB area allocation, and Figure 11 is a diagram for explaining the causes of service call. A configuration diagram of the toner degree control system, FIG. 12 is a flowchart showing toner density control processing, FIG. 13 is a partial block diagram of a control section for the transfer voltage applied to the transfer charger, and FIG. 14 shows how the image density changes. It is a figure for explaining a state. 20... Photoreceptor, 21... Charger (charging means), 22... Laser exposure unit (exposure means), 2
3...Developing device (developing means), 24...Transfer charger (transfer means), 33...Fixer unit (fixing means), 90...Semiconductor laser oscillator, 402...Control circuit (3 , j) means), 402c...
ROMB (counting means), 500... toner concentration detection sensor, P... paper (transferring material).

Claims (1)

[Scope of Claims] A photoreceptor, a charging means for uniformly charging the photoreceptor, an exposure means for exposing the photoreceptor uniformly charged by the charging means according to an image, and an exposure means a developing means for developing the electrostatic latent image formed on the photoreceptor by exposure to light; a transfer means for transferring the developer image obtained by the development of the developing means onto a transfer material; An image forming apparatus comprising a fixing means for fixing a transferred material to which a dye image has been transferred, a counting means for cumulatively counting the number of images formed, and when the counting means counts a predetermined value, An image forming apparatus comprising: a control means for changing transfer efficiency in the means.