JPH09311591A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of maintaining the durability of a cleaning blade by making the contact time of an image carrier with the cleaning blade as short as possible. SOLUTION: This device is provided with a press-contact releasing mechanism for releasing the press-contact of an electrifier, a write means, plural developing devices, a transfer roller and the cleaning blade with a photoreceptor drum, and a single step motor driving the press-contact releasing mechanism on the periphery of the photoreceptor drum. Furthermore, a CPU 510 is provided so that the transfer roller and the cleaning blade are released from the photoreceptor drum by driving a motor 79 in one direction in the case of shifting a mode to a sleep mode from an idling mode for controlling fixing temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus which controls a fixing temperature having an idling mode and a sleep mode particularly during non-printing, and more particularly to an image forming apparatus which has a driving mechanism for releasing pressure from a transfer device / cleaning blade. .

[0002]

2. Description of the Related Art An image forming apparatus adopting an electrophotographic process includes, for example, a fixing device including a heat roller and a pressure roller, and when a print start signal is received, the temperature is adjusted to a temperature higher than a standby temperature. Print,
There is a device that saves power during non-printing by controlling the standby temperature again. If the standby time becomes longer, the power consumption increases during the non-printing period. Therefore, it has been proposed to provide a sleep temperature lower than the standby temperature to maintain the speed of the first print time and save energy.

An image forming apparatus adopting such an electrophotographic image forming process cleans an image carrier to execute the next image process after completion of a charging process, an image exposure process, a developing process and a transfer process, as is well known. There is a transfer roller that employs a transfer roller that removes toner and the like remaining on the image bearing member by pressing the blade and causes less transfer deviation and lowers the transfer bias voltage. Such a transfer roller executes the transfer process in a state in which the recording paper is firmly pressed against the image forming body by the pressing mechanism. There is a cleaning blade used in a cleaning process as a device having a pressure contact mechanism.

The present applicant has proposed a drive mechanism in which the pressure release of the transfer device / cleaning blade is driven by a single step motor in order to reduce the number of parts of the drive mechanism.

[0005]

However, in the above-mentioned image forming apparatus, if the cleaning blade and the image carrier are left in contact with each other during non-printing, the deformation of the cleaning blade and the load applied to the blade and the holder. As a result, the adhesive strength is weakened and the drum cleaning performance is deteriorated.

An object of the present invention is to solve the above technical problems,
An object of the present invention is to provide an image forming apparatus capable of maintaining the durability of the cleaning blade by reducing the contact time between the cleaning blade and the image carrier as much as possible.

[0007]

The above object can be achieved by the following constitutions.

(1) A pressure release mechanism for pressing and releasing the charging device, the image exposure means, the plurality of developing devices, the transfer means and the cleaning means on the periphery of the image carrier, and the pressure release mechanism. An image forming apparatus provided with a single motor, wherein the transfer means and the cleaning means are driven by unidirectionally driving the step motor when shifting from an idling mode for fixing temperature control to a sleep mode. An image forming apparatus comprising a control unit for releasing the image carrier.

By providing the above configuration, for example, by holding the cleaning blade in a state of being released from the image carrier when shifting to the sleep mode, and shortening the contact time between the image carrier and the cleaning blade as much as possible. Since the deformation of the cleaning blade and the deterioration of the strength of the adhesive portion can be removed as much as possible, the durability of the cleaning blade can be maintained and the deterioration of the cleaning performance can be prevented.

[0010]

FIG. 1 is a sectional view showing a schematic configuration of an image forming apparatus according to the present embodiment, and FIG. 2 is a sectional view showing each cartridge according to the present embodiment.

The image forming apparatus according to the present embodiment has a main body 2 in which a cartridge containing various process members is loaded.
00, a double-sided paper feeding device 400 and a recording paper feeding device 600 are optionally provided.

First, the structure of each cartridge will be described with reference to FIGS.

As shown in FIG. 2, the equipment accommodated in the drum stand 30 includes a drum cartridge 40 in which the photosensitive drum 10 and others are incorporated, and a developing cartridge 50 in which each developing device 14 containing Y, M, and C developers is incorporated. Further, it is separately stored in the developing cartridge 50A in which only the developing device 14A containing the K developer is incorporated.

The drum cartridge 40 is the photosensitive drum 1.
In addition to 0, a PCL 11, a charger 12, and a cleaning device 22 are incorporated, and the openings 40A, 40B, and 40 corresponding to the areas of exposure, development, and transfer on the surface of the photoconductor are provided.
It covers all photoreceptor surfaces except C. In the drum cartridge 40, the bearing 41 of the photosensitive drum 10 is brought into contact with the vertical groove 30 </ b> A of the drum base 30, and the bottom part is brought into contact with a pair of position regulating pins P <b> 1 provided on both inner side surfaces of the drum base 30. In this way, after the rotation is prevented, the horizontal and vertical positions are regulated and each device to be accommodated is set to a predetermined image forming position.

As shown in FIG. 2, the opening 40A, which is the exposure area of the drum cartridge 40, is provided with a slidable shield plate 42 in an elongated slit hole having a width sufficient for a writing beam to pass therethrough. There is no way to get into.

On the other hand, the developing cartridges 50 and 50A
Are biased by the compression springs 52 in a state where the position regulating pins P2 of the respective developing devices projectingly engage with the elongated holes on both side surfaces. The developing cartridges 50 and 50A are pressed to the left by the pressing pin P3 or P4 provided on the side door 34 forming the right side surface of the drum base 30, and the abutting rollers (not shown) coaxial with the developing sleeves 141 are provided. The gap between the peripheral surface of each developing sleeve 141 and the peripheral surface of the photoconductor drum 10 is set by pressing the peripheral surface of the photoconductor drum 10 against the surface of the photoconductor drum.

The drum base 30 is a pedestal 30 installed above.
A plurality of toner replenishing means 300 for replenishing toner to each developing unit are provided integrally on the upper surface of B.

Each toner replenishing means 300 comprises a toner hopper 310 connected to each developing device by a toner carrying pipe (not shown) and a loading section 330 for mounting the toner cartridge 320 in a horizontal position. The toner replenishing means 300 are arranged adjacent to each other on the same plane in the axial direction of the developing sleeve 141 of the developing device 14. The developing sleeve 141 has a power source (not shown) for applying a DC bias and an AC bias set for each color, and the DC bias and the AC bias can be turned on / off individually under the control of the CPU 510.

The connection portion between the toner conveying pipe (not shown) and each developing device is released and connected in accordance with the withdrawal and insertion of each developing device. That is, when the drum base 30 is pulled out for jam processing, drum cartridge replacement, or the like, the connecting portion between the toner transport pipe (not shown) and the developing device does not separate, and the connecting portion is opened only when taking out each developing device. The toner stains were reduced because they were separated. Further, since it is not necessary to separate the toner replenishing means 300 from the developing device 14 when the drum base 30 is taken out, the construction of these devices is simplified and at the same time the handling operation is simplified.

As shown in FIG. 1, the image forming apparatus is provided with a recording paper passage detection sensor 70 for detecting the recording paper between the transfer roller 216 and the cleaning device 22.

The transfer roller 216 is equipped with a power source (not shown) capable of applying a positive polarity or negative polarity transfer bias.
Switching is performed under the control of the PU 510. When the recording paper exists at the transfer portion, the polarity of the bias voltage to the transfer roller 216 is set to the opposite polarity to the polarity of the toner. When the recording paper passes through the transfer roller 216 and the photosensitive drum 10 and the transfer roller 216 come into direct contact with each other at the transfer portion, the polarity of the bias voltage to the transfer roller 216 is made the same as the charging polarity of the toner. To do. When the recording paper is not present at the transfer portion, the polarity of the bias voltage to the transfer roller 216 is set to be the same as the polarity of the toner. By thus determining the operation of the transfer roller 216, when image formation is continuously performed, the transfer roller 216 can be quickly cleaned in the period between adjacent recording sheets. Such a control method is also effective when the size of the transfer material in the traveling direction is not known in advance, for example, for manual feeding.

As a means for removing the residual toner remaining on the surface of the photosensitive member without being transferred, an elastic body such as polyurethane rubber having excellent abrasion resistance is used as a cleaning blade. As the polyurethane elastic body, generally, polyurethane synthesized by addition reaction with isocyanate, polyol and various hydrogen-containing compounds is used.

As shown in FIG. 1, the main body 200 is provided with a manual paper feed mechanism 270. The manual paper feed mechanism 270 has an insertion hole 271 into which a recording sheet is inserted and a recording paper inserted into the insertion hole 271. A detection member for detecting the paper is provided. The leading end of the inserted recording paper hits the built-in paper feed roller 272 and stops. The recording paper is conveyed by the rotation of the paper feed roller 272, and is conveyed toward the registration rollers 209 via the conveyance path 273. The manual feed mechanism 270 is the main body 2
The shaft is fixed to the shaft at 00 and is slightly movable outward.
Further, a part of the outer member is supported by the shaft, and the insertion hole can be opened.

A paper feed cassette 203 containing a plurality of recording papers in the main body 200 is detachably provided as shown in FIG. A half-moon-shaped paper feed roller 202 for feeding recording paper is provided on the paper feed cassette 203, and the paper feed cassette 2
A push-up plate 204 for pressing the uppermost recording sheet against the separation claw 205 is provided in the inside of the sheet. The recording paper placed on the push-up plate 204 is constantly pushed upward by a spring (not shown), the leading end of the recording paper is locked by the separation claw 205, and the recording paper is fed by the operation of an electromagnetic clutch (not shown). Roller 202
Is driven, and the uppermost sheet of recording paper is separated by the separation claw 205 and fed. The fed recording sheet is driven and conveyed by the intermediate sheet feeding roller 206, and is guided to the registration roller 209. CPU downstream of the registration roller 209
A registration shutter 215 for opening and closing the registration unit in accordance with a control signal from 510 is provided. The detection member 219 is operated by the CPU 510, and when the detection member 219 detects the recording paper, the recording paper directly enters the registration roller 209 and is stopped by the registration shutter 215. Further, a sensor 189 for detecting the transparency of the recording paper surface is provided upstream of the registration roller 209 in the paper feeding. At this time, the leading end of the recording paper abuts on a projection provided on a part of the transmission sensor 189 which is rotatably fixed to a part of the main body 200 on the upper part of the guide member 213, and along the image forming surface of the recording paper. After the transmission sensor 189 is arranged at a predetermined position, the transparency of the image forming surface formed on the recording paper is detected.

A detection member for detecting the recording paper is provided above the paper feed cassette 203. Intermediate paper feed roller 20
Reference numeral 6 denotes a sheet cassette 203 and a curved reversing guide member 212.
It is provided between and.

The recording paper guide member 210 is the registration roller 2
The recording paper having passed through the transfer roller 09 is guided toward the transfer roller 216 which can be pressed and separated from the photosensitive drum 10.

The fixing device 220 is a device for fixing the image transferred on the recording paper, and comprises a heating roller 221 and a pressure roller 222. The heating roller 221 has a diameter of 245.7.
A 450 μm thick silicone rubber layer and a 50 μm thick PFA layer are formed on a substrate having an outer diameter of 1.6 mm and a diameter of 1.6 mm. The fixing heater 224 is provided in the base of the heating roller 221.
Has been inserted. The heating roller 221 detects the surface temperature by the fixing temperature sensor Th and controls it so that it is always constant. The fixing temperature sensor Th is composed of a thermistor or the like, detects the surface temperature of the heating roller 221 to turn on / off the fixing heater 224 of the heating roller 221, and detects the surface temperature of the heating roller 221 to detect an abnormally high temperature. It is used to stop the power supply to the fixing heater 224 when the temperature is reached. The fixing temperature sensor Th is provided in a non-transfer material region (a region that is not affected by toner, paper dust, etc.) in which the transfer material P and the heating roller 221 do not come into contact with each other when the transfer material P passes, and thus the fixing temperature sensor Th is related to the paper passing time. Therefore, the initial detection accuracy can be maintained. The pressure roller 222 has a surface layer such as rubber. The paper discharge roller 223 is the fixing device 2
The recording paper is ejected from the sheet 20, and the ejected recording paper is conveyed upward by the conveying roller 291. Conveyor roller 291
The recording paper conveyed upward by the main body 200 is discharged by the discharge rollers 292 provided in the discharge passage formed in the main body 200.
The recording surface is discharged face down on a paper discharge tray 210 provided on almost the entire surface of the upper part. A paper ejection detection sensor 229 is provided in the paper ejection path of the fixing device 220.

A motor (not shown) transmits a driving force to the sheet feeding roller 202 and the intermediate sheet feeding roller 206 via a reduction mechanism (not shown) via a toothed pulley and an intermediate gear group. It The paper feed roller 202 is intermittently driven by an electromagnetic clutch (not shown). On the other hand, the registration roller 209 and the intermediate sheet supply roller 206 are configured to be driven and rotated at all times.

Next, the pressure release of the transfer roller 216 and the cleaning blade 22A and the toner replenishment selection mechanism will be described with reference to FIGS.
This will be described with reference to FIG.

FIGS. 3 and 4 are diagrams of the pressure release mechanism of the transfer roller and the cleaning blade, and FIG. 5 is a time chart showing the operation timing of the drive mechanism shown in FIGS.

The motor 79 rotates clockwise outside the image formation, so that the gear G10 on the motor shaft also rotates the sun gear G13 clockwise through the gear G11 and the coaxially integrated gear G12. As shown in FIG. 3, the planetary gear G14 on the rotatable support plate 26 is revolved clockwise to drive the gear G15, and if necessary, for example, an operation such as color selection of toner to be supplied to the developing device 14 is performed.

The motor 79 rotates counterclockwise with the start of image formation to rotate the planet gear G14 as shown in FIG.
Revolves in the counterclockwise direction, and rotates the gear G20 connected to the pressing drive of the transfer roller 216 in the counterclockwise direction.

The gear G20 is a gear G21 integrally formed with the cam plate 30 via a gear G21 coaxially integrated with a gear G22.
To transmit the power rotating counterclockwise.

The cam plate 30 is integrally formed with a cylindrical cam C having two large and small radii of curvature R and r, and notches 30A and 30B corresponding to the fixed photosensors are provided at four equally divided positions on the outer peripheral edge thereof. , 30C and 30D and 30E.

A pressing member 40, which is bent in a U-shape and rotates around a shaft 40A as a fulcrum, presses the tip end portion 40B of the cam C by the urging force of a tension spring 41, and the pressing member 40 further presses the cam C. A pressure contact lever 50 that supports the transfer roller 216 is pressed against the pin 42 by the biasing force of the tension spring 51.

As shown in FIG. 3, the cam plate 30 defines the angle at which the notch 30A is detected by the photosensor as the rotational neutral position (NP), and at this angle the cam C has a large radius of curvature R. The tip portion 40B of the pressing member 40 is brought into pressure contact. Therefore, the pressing member 40 occupies the position rotated counterclockwise, and the pressing pin 42 presses the protrusion 42 of the pressing lever 50 to move the pressing lever 50 to the shaft 50.
It is placed in a position rotated clockwise with A as a fulcrum, whereby the transfer roller 216 is retracted to a position separated from the peripheral surface of the photoconductor drum 10 in the neutral position (N · P).

When the motor C rotates in the counterclockwise direction as shown in FIG. 4 to rotate the cam C to press the tip portion 40B of the pressing member 40 into contact with the portion having the small radius of curvature r, the pressing member 40 moves clockwise. Occupies a position rotated in the direction, and the pressing pin 42 is separated from the protrusion 52 of the pressing lever 50 to free the pressing lever 50, whereby the transfer roller 21.
6 is pressed against the peripheral surface of the photosensitive drum 10 by the urging force of the tension spring 51 to start the image transfer operation.

The rotation speed of the motor 79 is controlled by a detection signal generated by the photosensor sequentially detecting each notch of the cam plate 30 as shown in FIG. Notches 30D and 30E
Is continuously detected, the pressure contact of the transfer roller 216 is released, and the cam C is stopped again at the position where the notch 30A is detected.
Is again set to the initial position shown in FIG. 3, that is, the neutral position described above.

FIG. 6 is a flowchart showing the cam task.

Such a cam task judges whether the postcard mode and the normal size mode and whether it is multi-color or mono-color, and determines the pressure release speed of the transfer roller 216 and the blade depending on each recording paper mode. And a toner replenishment selection operation.

The CPU 510 sets the motor 79 to 50 according to the recording paper size mode input from the operation unit (not shown).
Whether the motor rotates at 0 PPS to detect the neutral position (power-on time) (step 101), the motor 79
Is rotated at 300 PPS to detect the neutral position (printing time) (step 102), or the motor 79 is rotated at 500 PPS to turn on the transfer roller and the cleaning blade 22A (step 103).
Make a judgment.

If the CPU 510 makes a positive determination in step 101, it rotates the motor 79 at 500 PPS (step 104), and removes 100 m to remove noise.
After waiting for sec (step 105), the neutral position detection process is performed (step 106).

If the CPU 510 makes a negative determination in step 101 and makes a positive determination in step 102, it rotates the motor 79 at 300 PPS (step 1
07), 20 msec is waited for noise removal (step 108), and neutral position detection processing is executed (step 106).

If the CPU 510 makes a negative determination in steps 101 and 102, and makes a positive determination in step 103, it rotates the motor 79 at 500 PPS (step 109) and waits for 1.5 seconds (monocolor printing). Sometimes used) (step 110), edge detection processing is performed (step 111).

If the CPU 510 makes a negative determination in steps 101 to 103, the CPU 510 sets the motor 79 to 30
It rotates at 0 PPS (step 112), waits 20 msec for noise removal (step 113), and executes edge detection processing (step 111).

By activating the above-mentioned cam task, the image forming apparatus according to the present embodiment can release the pressure from the transfer roller 216 and the blade at a speed corresponding to the recording paper size mode, and can also perform the toner replenishing operation. Since it is possible to follow the transfer roller 216, the transfer roller 216 can be used, for example, in a printing operation of a small size such as a postcard size.
Since the pressure release operation of the blade and the blade can be performed at high speed at 500 PPS, it is possible to prevent the transfer roller 216 from being soiled and the back surface of the recording paper to be soiled due to the delay of the pressure release operation of the transfer roller 216. In the normal recording size mode such as the B size, the transfer roller 216 and the cleaning blade 22A during the printing operation.
Since the pressure release operation can be performed at a low speed of 300 PPS, proper image reproduction can be performed without causing writing deviation due to vibration of the photosensitive drum 10.

The above is the schematic mechanism of the image forming apparatus according to the present embodiment.

Next, FIG. 7 shows a schematic configuration of the engine controller 500 used in the image forming apparatus according to the present embodiment.
This will be described with reference to FIG.

FIG. 7 is a block diagram showing an engine controller 500 according to this embodiment.

The engine controller 500 receives page data and print parameters from an external device such as a personal computer via a print controller (not shown), and writes the write device 230, the scorotron charger 12, the developing device 14, and the transfer device. The drive timing of the roller 216 and the cleaning device 22 is controlled, and the paper feeding device 4
00, the paper feed cassette 203, and the manual paper feed mechanism 270 control the paper feed timing of the recording paper, and further control the fixing temperature and the rotation of the electric fan 280. The engine controller 500 includes a CPU 510 and an SRAM 5
20 and a gate array 530 and the like. The configuration of each part will be described below.

The CPU 510 executes a sequence program for executing the electrophotographic process from the SRAM 520 by using a reference signal for one round of the drum, which is an external signal, as a trigger, and controls a driving state of a motor driver (not shown). , Passage detection sensors 70, 189, 219,
The conveyance state of the recording paper is controlled based on the detection signal from 229 (see FIG. 1), and the fixing temperature is controlled to a predetermined value for each operation mode via the gate array 530.

The CPU 510 has a built-in continuous print counter for counting the number of continuous print requests.

In the present embodiment, the set temperature for fixing the toner image on the plain paper is 165 ° C to 170 ° C.
The set temperature for fixing the toner image on the OHT is set in the range of 180 ° C to 185 ° C, and the set temperature of the idling period is set in the range of 135 ° C to 145 ° C. The standby temperature is set to 120 ° C. Therefore, the CPU 510
In various modes, the fixing lamp ON / OFF signal is sent so that the temperature falls within the upper and lower set temperatures of the set temperature range.

The SRAM 520 has a warm-up process, a multi-color print process, a mono-color print process, a letter size print sequence, a paper feed process including a postcard size print sequence and a purge process, and a manual paper feed. The data and programs for controlling the surface temperature of the heating roller 221 for each mode and the parameters necessary for executing the processing and the program corresponding to the double try sequence and various print sequences are stored.

[0055]

[Table 1]

Table 1 shows data for obtaining the low-speed rotation timing determined by the number of continuous prints and the color mode.

The gate array 530 has a developing device drive system, a transfer cleaning drive system, a paper feed drive system, and a fixing temperature control function. The developing device driving system controls the operation of the driving mechanism of the toner supply device by selecting the driving state of the driving mechanism of the developing device. The transfer cleaning drive system instructs the state of pressing / releasing the cleaning blade and the transfer roller 216 to and from the photosensitive drum 10 in the various sequences described above. The paper feed drive system controls the transport speed of the recording paper according to the print size, print mode, and the like.

The gate array 530 receives a signal indicating the fuse temperature, and achieves a watchdog function of cooling the heating roller 221 by forcibly stopping the heating operation of the fixing heater 224 by hardware at the time of program runaway.
Therefore, when the CPU 510 detects the runaway of the fixing temperature control program based on the input obtained from the gate array 530, the watchdog function is realized by cutting the main relay and the AC power supply 224a by the operation of the hardware. are doing.

The gate array 530 turns on / off the fixing heater 224 by sending a control signal of the fixing heater 224 to the fixing heater 224 according to each operation mode.
Controlled off. Specifically, the fixing heater 224 is
Heating time of 1.5 sec and 4 sec during non-paper feed period
The non-heating time is periodically repeated for plain paper and O
Heating time of 1 sec and 4 sec during the fixing operation of HT
The non-heating time of c is periodically repeated.

Fixing heater 224 in heating roller 221
Is an AC power supply 224a and a phototriac coupler 2
It is connected to 44b. Phototriac coupler 24
In 4b, the phototriac 244c is short-circuited, and the fixing heater 224 is supplied with an AC current. on the other hand,
The output port P2 of the gate array 530 is a resistor 224d.
Is connected to the resistor 224d to which the base and one end of the transistor 224e are connected. The transistor 224e has a grounded emitter, and the collector side is connected to the diode 244f. The anode of the diode 244f is connected to the resistor 244g. The resistor 244g is connected to the DC power source (+ 5V). Therefore, when the output port P2 of the gate array 530 is at the H level (ON state), the fixing heater 224 is energized, and when it is at the L level (OFF state), the fixing heater 224 is deenergized. Further, the thermistor 225a installed near the heating roller 221 has a DC power source (+5
V), and the other terminal is connected to the resistor 225b and the analog input port (A / D port) of the gate array 530. The gate array 530 detects the temperature of the heating roller 221 by the analog voltage V _T determined by the resistance values of the thermistor 225a and the resistor 225b.

The driver transistor 281 for driving the electric fan 280 is coupled to the gate array 530 via the base resistor 282. The counter electromotive force absorbing diode 283 of the electric fan 280 is connected between the collector of the driver transistor 281 and the 24V power source of the electric fan 280. The gate array 530 is the CPU 5
When the transistor 281 is turned on by the control of 10, the electric fan 280 is stopped.

The above is the schematic configuration of the engine controller 500 in the present embodiment.

FIG. 8 shows the surface temperature of the fixing roller and the change with time during the print sequence, and the turning on / off of the fixing heater.
It is a graph showing an off state.

First, when the power is turned on, the fixing heater 2
24 turning on, the surface temperature of the heating roller 221 is heated to the standby temperature (for example, 140 ° C.), and turns on the main motor, the temperature T _H of the heating roller 221 detected by the thermistor 225a is equal to or higher than the predetermined standby temperature To judge. In the following cases, the halogen lamp 94 is turned on and the main motor is kept on. This is called a warm-up state.

[0065] When the temperature T _H of the heating roller 221 reaches a predetermined idling temperature, turns off the main motor 23,
It is determined whether the temperature of the heating roller 221 is equal to or higher than the idling temperature, and if the temperature is equal to or higher than the idling temperature, the fixing heater 224.
Is turned off, and if the temperature of the heating roller 221 is lower than the standby temperature, the fixing heater 224 is turned on. The presence or absence of a print instruction from the external device is determined, and the above-described operation is repeated. This is the idling state. The heating roller 221
The surface temperature of is reduced by heat dissipation, so it is kept on and off repeatedly to maintain the idling temperature.

The heating roller 221 is adjusted to the standby temperature in the idling state. If it is determined that there is a print instruction in such a standby state, the main motor is turned on and the surface temperature of the heating roller 221 is raised to the print temperature (for example, 180 ° C.). Even during printing, the surface temperature of the heating roller 221 decreases due to heat dissipation, so the control signal is repeatedly turned on / off to maintain the printing temperature. If the temperature T _H of the heating roller 221 is equal to or higher than the print temperature T _{P, the} fixing heater 224 is turned off, and if not, the fixing heater 224 is turned on to determine whether or not there is a print instruction.
This is the print state.

Thereafter, when it is determined that the heating roller 221 is in the standby state, the surface temperature of the heating roller 221 is set to the sleep temperature (for example, 120 ° C.). Heating roller 2 even in the standby state
Since the surface temperature of 21 is lowered by heat radiation, the control signal is repeatedly turned on / off to keep the surface temperature of the heating roller 221 at the standby temperature.

A print sequence in the image forming apparatus of this embodiment will be described.

FIG. 9 is a flow chart showing a print sequence in this embodiment.

When the CPU 510 receives the print start request command, it starts the print start task (step 1). Specifically, as shown in FIG. 2, the CPU 510 (see FIG. 7) grounds the photoconductor drum 10 having the OPC photoconductor coated on the drum and drives and rotates the photoconductor drum 10 in the clockwise direction. The CPU 510 rotates a polygon mirror (not shown). This stabilizes the rotation of the photoconductor drum 10 and the polygon mirror. Further, the CPU 510 initializes the content of the print register α for determining whether continuous printing is performed to 0.

The CPU 510 activates the sequence start task (step 2). As a result, the CPU 51
0 sets various modes.

When the CPU 510 receives the reference interrupt signal in one rotation cycle of the photosensitive drum 10, it starts the image start task (step 3). Specifically, C
The PU 510 is a scorotron charger 12 that uniformly charges VH on the peripheral surface of the photoconductor drum 10 by corona discharge using a grid and a corona discharge wire whose potential is held at VG. Prior to the charging by the scorotron charger 12, in order to eliminate the history of the photoconductor up to the previous print, exposure is performed by the PCL 11 using a light emitting diode or the like to eliminate the charge on the peripheral surface of the photoconductor.

Writing device 2 after uniformly charging the photosensitive member
Image exposure is performed by 30 based on the image signal. The writing device 230 is a device in which an optical path is bent by a reflection mirror through a polygon mirror, a fθ lens, etc., which rotates using a laser diode (not shown) as a light source, and scanning is performed.
A latent image is formed by rotation (sub-scanning) of the photosensitive drum 10. In the present embodiment, a character portion is exposed to form a reversal latent image such that the character portion has a lower potential VL.

At the periphery of the photosensitive drum 10, there are provided developing units 14 each containing a developer consisting of toner such as yellow (Y), magenta (M), cyan (C) and black (K) and a carrier. First, the development of the first color is performed by the developing sleeve 141 which contains a magnet and holds the developer and rotates. The developer consists of a carrier in which ferrite is used as a core and is coated with an insulating resin around it, and a toner whose main component is polyester and pigments according to the color and charge control agents, silica, titanium oxide, etc. are added. The agent is regulated by the layer forming means to have a layer thickness (developer) of 100 to 600 μm on the developing sleeve 141 and is conveyed to the developing area. The gap between the developing sleeve 141 and the photosensitive drum 10 in the developing area is set to 0.2 to 1.0 mm, which is larger than the layer thickness (developer), and the AC bias of VAC and the DC bias of VDC are superposed and applied between them. It Since VDC and VH and the toner are charged in the same polarity, the toner that has been given the opportunity to be separated from the carrier by VAC does not adhere to the VH portion where the potential is higher than VDC, but adheres to the VL portion where the potential is lower than VDC. Then, visualization (reversal development) is performed.

When the CPU 510 receives the reference interrupt signal again after the visualization of the first color is finished, the CPU 510 enters the image forming process of the second color and performs the uniform charging by the scorotron charger 12 again to perform the image of the second color. A latent image with data is formed by the writing device 230. At this time, the charge elimination by the PCL 11 performed in the image forming process of the first color is not performed because the toner attached to the image portion of the first color scatters due to the sudden decrease in the potential around the image. Photoconductor drum 10 again
Of the photoconductors that have the potential of VH over the entire surface,
A latent image similar to that of the first color is formed and developed on the portion without the image of the first color, but in the portion where the image with the image of the first color is developed again, the toner attached to the first color causes The latent image of VM 'is formed by the light shielding and the electric charge of the toner itself, and the development is performed according to the potential difference between VDC and VM'. In the overlapping portion of the images of the first color and the second color, if the development of the first color is performed by forming a latent image of VL, the balance between the first color and the second color is lost, so that the exposure amount of the first color is reduced and VH> The intermediate potential is such that VM> VL. C
If the PU 510 receives the reference interrupt signal for the third and fourth colors in the same manner as the second color, the PU 510 executes the image forming process and forms a visible image of four colors on the peripheral surface of the photosensitive drum 10.

On the other hand, from the paper feeding cassette 203 to the paper feeding roller 2
The recording paper conveyed through the sheet No. 02 is temporarily stopped, and is fed to the transfer area by the rotation operation of the registration roller 209 when the transfer timing is adjusted. In the transfer area, a transfer roller 216 is pressed against the peripheral surface of the photosensitive drum 10 in synchronization with the transfer timing, and the fed recording paper is sandwiched to transfer the multicolor image at once. Next, the recording paper is separated into brushes 21 separated from each other at almost the same time as shown in FIG.
The charge is removed by 7 and is separated by the peripheral surface of the photoconductor drum 10 and conveyed to the fixing device 220. The toner is fused by heating and pressurizing the heating roller 221 and the pressure roller 222, and then discharged to the outside of the apparatus via the paper discharge roller 223. Is discharged.

After the sequence start task is activated, the CPU 510 activates the image end task for each paper size (step 4). Specifically, the CPU 510 stops the rotation of the developing sleeve 141 and turns off the developing bias and the like. The CPU 510 prepares for the next toner image by separating the transfer roller 216 and the separation brush 217 from the peripheral surface of the photosensitive drum 10 after passing the recording paper. On the other hand, CP
In U510, the photosensitive drum 10 from which the recording paper is separated is brought into pressure contact with the blade of the cleaning device 22. As a result, the residual toner is removed / cleaned, the charge is removed again by the PCL 11 and the charge by the charger 12, and the next image forming process starts. The blade moves immediately after the cleaning of the photoconductor surface and retracts from the peripheral surface of the photoconductor drum 10.

The CPU 510 activates the check task (step 5). As a result, the CPU 510 determines whether or not the next print start command is received from the print controller (not shown). When the CPU 510 receives the start command from the print controller (not shown) (step 6), the operations after step 2 are executed again. If the CPU 510 does not receive the start command from the print controller (not shown), the CPU 510 executes the print end task (step 7).
Specifically, the CPU 510 makes the rotation of the polygon mirror half speed, and stops the rotation of the photosensitive drum 10. This ends the print sequence.

The CPU 510 drives the standby task upon completion of the print end task (step 8).
As shown in Table 1, the CPU 510 waits for the time determined by the color mode and the number of continuous prints to elapse, and rotates the fan at half speed. The CPU 510 waits for the lapse of a time obtained by subtracting the time determined by the table shown in Table 1 below from 3 minutes, stops the polygon motor by this lapse of time, and sets the fixing set temperature to 165 ° C.

The above is the print sequence of the image forming apparatus according to the present embodiment.

Next, the communication task and sleep stop task will be described with reference to FIGS.

FIG. 10 is a flowchart showing communication tasks.

Here, the communication task is an operation of interpreting and executing the command transmitted from the print controller and returning the status.

The CPU 510 maintains the / CRDY signal in the low level state, accepts the command from the print controller, and sets the / CRDY signal to the high level when the basic status corresponding thereto is returned. In this way, the CPU 51
0 is connected to a print controller (not shown), / COMRQ signal, / CRDY signal, / READ
Judgment processing of various commands is performed while processing control signals such as Y signal and / ERROR signal (step 11).
0).

The CPU 510 determines whether or not the command whose contents are analyzed in step 110 is a sleep execution command (step 120).

If the CPU 510 determines in step 120 that the command is not a sleep command, it performs a reply process for returning the basic status corresponding to the command analyzed in step 110 (step 140). As a result, the CPU 51
0 sets the / CRDY signal to high level.

On the other hand, if the CPU 510 determines in step 120 that it is a sleep command, it activates a sleep stop task (step 130) and returns a status indicating that it is in sleep mode (step 14).
0). That is, the engine controller 500 returns a status indicating the sleep mode in response to a command received from a print controller (not shown) when shifting from the idling state to the sleep mode.

The above is the outline of the communication task in and after the sleep mode in the present embodiment.

FIG. 11 is a flowchart showing the sleep stop task.

The CPU 510 executes step 1 shown in FIG.
When the sleep stop task is activated at 30, the transfer roller 216 and the cleaning blade 22A are released as described with reference to FIG. 4 (step 13).
1).

Specifically, the motor 79 rotates counterclockwise with the start of image formation to revolve the planetary gear G14 counterclockwise as shown in FIG.
The gear G20 connected to the pressure contact drive of No. 6 is rotated counterclockwise. The gear G20 is the same as the coaxial gear G21 to the gear G21.
The power for rotating in the counterclockwise direction is transmitted to the gear G23 having the cam plate 30 as an integral unit via 22. As a result, the cam plate 30 is notched by the photo sensor as shown in FIG.
The angle at which A is detected is set as the rotational neutral position (N · P), and at this angle, the cam C presses the tip portion 40B of the pressing member 40 against the portion having the large radius of curvature R. Therefore, the pressing member 40 occupies the position rotated in the counterclockwise direction, and the pressing pin 42 causes the protruding portion 4 of the press contact lever 50 to move.
2 is pressed to place the pressing lever 50 in a position rotated clockwise about the shaft 50A as a fulcrum, whereby the transfer roller 216 is separated from the peripheral surface of the photosensitive drum 10 in the neutral position (N · P). Have been evacuated to.

The CPU 510 turns off various other loads (step 132), waits 100 msec (step 133), and turns off the 24V power supply (see FIG. 7) (step 134).

The CPU 510 waits for the lapse of 100 msec again (step 135), and the 5V power source (see FIG. 7).
Is turned off (step 136), and various buffers and flags are cleared (step 137). This puts the machine into sleep mode.

The return from the sleep mode is performed by the sleep mode release command from the print controller. At this time, the fixing heater 224 is warmed up and the transfer roller / cleaning blade is moved to N · P to wait for reception of a print start request command.

The image forming apparatus according to the present embodiment is provided with the above-described structure, and for example, when the cleaning blade 22A is released from the photoconductor drum 10 when the sleep mode is entered, the image forming apparatus holds the photoconductor drum 10 and the cleaning blade 22A. By shortening the contact time with the cleaning blade 22A as much as possible, the deformation of the cleaning blade 22A and the deterioration of the strength of the adhesive portion can be removed as much as possible.
It is possible to maintain the durability of the cleaning blade 22A and prevent deterioration of the cleaning performance.

[0096]

As described above, according to the present invention, the contact time between the image bearing member and the cleaning blade is maintained by keeping the cleaning blade released from the image bearing member when shifting to the sleep mode. By shortening as much as possible, the deformation of the cleaning blade,
Since the deterioration of the strength of the adhesive portion can be removed as much as possible, the durability of the cleaning blade can be maintained and the deterioration of the cleaning performance can be prevented.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus according to an embodiment.

FIG. 2 is a cross-sectional view showing each cartridge according to the embodiment.

FIG. 3 is a view showing a pressure release mechanism of a transfer roller and a cleaning blade.

FIG. 4 is a view showing a pressure release mechanism of a transfer roller and a cleaning blade.

5 is a time chart showing the operation timing of the drive mechanism shown in FIGS. 3 and 4. FIG.

FIG. 6 is a flowchart showing a cam task.

FIG. 7 is a block diagram showing an engine controller according to the present embodiment.

FIG. 8 is a graph showing a surface temperature of a fixing roller, a temporal change, and an ON / OFF state of a fixing heater during a print sequence.

FIG. 9 is a flowchart showing a print sequence according to the present embodiment.

FIG. 10 is a flowchart showing communication tasks.

FIG. 11 is a flowchart showing a sleep stop task.

[Explanation of symbols]

 10 Photosensitive Drum 12 Charging Device 14 Developing Device 22A Cleaning Blade 79 Motor 216 Transfer Roller 220 Fixing Device 221 Heating Roller 222 Pressing Roller 224 Fixing Heater 230 Writing Device 500 Engine Controller 510 CPU 520 SRAM 530 Gate Array

Claims (1)

[Claims] 1. A pressure release mechanism for releasing pressure from a charger, an image exposure unit, a plurality of developing units, a transfer unit and a cleaning unit on the periphery of an image carrier, and a single unit for driving the pressure release mechanism. In the image forming apparatus provided with one motor, the transfer means and the cleaning means are driven by driving the motor in one direction when the idle mode for fixing temperature control is changed to the sleep mode. An image forming apparatus, comprising: a control unit that releases the image from the image forming apparatus.