JPH09146318A - Copying machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deviation in transfer by controlling paper feeding by removing the malfunction of a resist shutter due to the erroneous detection of the trailing edge of transfer material caused by the deflection of the transfer material. SOLUTION: This copying machine is provided with a carrying roller 43 feeding the transfer material P fed from plural paper feeding paths toward a resist roller 44, and the resist shutter and a resist sensor on this side in the paper feeding direction of the roller 44. The scanning of a reading scanning unit 10 is started with the delay of a specified time after detecting the on-edge of a detection signal generated from the resist sensor, and the off-edge of the detection signal is not detected for the time t1 after detecting the on-edge of the detection signal. In such a state, the resist shutter is retreated and also the roller 44 is rotated to feed the transfer material so that the point of time when the leading edge of the transfer material P reaches a photoreceptor drum 31 may coincide with the point of time when the leading edge of an original image carried on the drum 31 reaches a transfer part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine, and more particularly to a copying machine provided with a paper feed control means for controlling the feeding of a transfer material.

[0002]

2. Description of the Related Art Generally, a copying machine starts scanning of a reading scanning unit with a delay of a predetermined time after detecting a leading edge detection signal generated by a registration sensor arranged in front of a transfer device on a paper feeding path. Therefore, the resist shutter should be retracted so that the time when the leading edge of the transfer material reaches the photosensitive drum after the leading edge detection signal is generated coincides with the time when the leading edge of the original image carried on the photosensitive drum reaches the transfer portion. This is what is called resist control. The reason why the reading and scanning unit starts driving with a predetermined delay after the leading edge detection signal is generated is to adjust the registration.

After the transfer / separation process is executed at the above-mentioned registration timing, the fixing process is carried out by the fixing device and the paper is discharged to the paper discharge tray. More specifically, the state of conveyance of the transfer material is stopped by the registration shutter in front of the registration roller by an amount corresponding to a distance for correcting the case where there is a slip between the transfer material and the sheet feeding mechanism. Such a registration shutter detects the trailing edge signal of the front page transfer material from the registration sensor in advance, and then projects onto the sheet feeding path to stop the next transfer material. The registration shutter retracts from the paper feed path at the registration timing described above. As a result, the transfer material is conveyed without stopping until it is fed to the nip portion of the registration roller by the rotation of the carry-out roller and then discharged.

[0004]

However, in the conventional copying machine, there is a case where a transfer deviation occurs due to an erroneous detection of the trailing edge of the transfer material or an erroneous operation of the shutter. This phenomenon is shown in FIG.
This will be described with reference to FIG.

FIG. 11A shows an erroneous detection of the trailing edge of the transfer material due to bending of the transfer material.

The office where the copying machine is installed can be controlled to some extent even in a warm and humid country such as Japan by fully equipped with an air conditioning system. However, the transfer material is easily affected by the temperature and humidity of the environment and may be bent. In addition, even when the transfer material does not smoothly enter the registration roller, the bending may occur.
FIG. 11A shows a state in which the bent transfer material has entered the registration roller. The transfer material must urge the actuator of the registration sensor to the position shown by the solid line, but the actuator will return to the position shown by the dotted line due to the bending of the transfer material. Under such a condition, the signal from the registration sensor has already sent the trailing edge detection signal. Due to such a phenomenon, the output signal from the registration sensor generates a pulse. The solenoid may be driven by such a pulse, and the resist shutter may project in the paper feed path. As a result, there has been a problem that the transfer speed of the transfer material is changed to cause transfer deviation (see FIG. 11B). Such malfunction has caused a problem in paper feed control.

FIG. 12 is a schematic diagram showing a transfer deviation caused by chattering of an actuator constituting a registration sensor.

The copying machine must be provided with a resist sensor having an actuator in order to be able to deal with transfer materials having different transparency such as OHP sheets and papers.

The registration sensor including such an actuator is provided with a spring or the like to suppress the chattering phenomenon so as to return to the initial position. Even with a resist sensor having such a device, a chattering phenomenon may occur when the number of continuous copies or the total number of copies increases. After the transfer material has passed through the actuator, it should have returned to the position shown by the solid line in the main body and stopped, but if the chattering phenomenon occurs in the above-mentioned situation,
Chattering may occur up to the position indicated by the dotted line.

Further, the above-mentioned conventional copying machine is provided with a double feed preventing mechanism. However, due to various bad conditions, there is a phenomenon in which an extra transfer material is fed in addition to the transfer material for the set number of copies due to a so-called "forwarding phenomenon". Such a feeding phenomenon is a phenomenon in which an extra transfer material is conveyed at a minute interval. A conventional copying machine does not have a function of detecting a sheet discharge by a trailing edge detection signal from a sheet discharge sensor and detecting a feed. In such a case, the transfer material may remain in the fixing device. There was a concern that such a transfer material would burn.

The conventional number of A4 copies per minute is 3
In the copying machine having 0 or less sheets, the mechanism other than the scanning / reading unit, especially the paper feeding mechanism and the developing sleeve, are simultaneously on / off controlled for cost reasons. Further, in the conventional copying machine, in order to reduce the whistling noise between the optical motor and the main motor, for example, the completion of paper ejection by the generation of the trailing edge detection signal from the paper ejection sensor and the return of the reading and scanning unit to the reference position are performed. The main motor was stopped by detecting both. Under such circumstances, the driving time of the developing device per maintenance volume is longer than necessary, and it is particularly noticeable in intermittent copying of small size and continuous copying of small size. Such a phenomenon has resulted in deterioration of the developer.

In view of the above technical problems, the first object of the present invention is to eliminate the malfunction of the resist shutter due to the false detection of the trailing edge of the transfer material due to the bending of the transfer material, and to control the sheet feeding to transfer misregistration. An object of the present invention is to provide a copying machine capable of preventing the occurrence of

In view of the above technical problems, a second object of the present invention is to provide a copying machine capable of preventing erroneous detection of a transfer material due to chattering of a registration sensor.

In view of the above technical problems, a third object of the present invention is to detect residual transfer material on a fixing device due to feeding, regardless of the output waveform from the transfer material sensor and the transfer timing of the transfer material sensor. Therefore, it is an object of the present invention to provide a copying machine capable of preventing the transfer material remaining in the fixing device from burning.

In view of the above technical problems, a fourth object of the present invention is to provide a copying machine capable of improving the durability of the developer by reducing the driving time of the developing device per maintenance copy volume. To do.

[0016]

[Means for Solving the Problems]

(1) A delivery roller that feeds transfer material fed from a plurality of paper feed paths toward a registration roller, and a registration shutter and a registration sensor are provided in front of the registration roller in the paper feeding direction. The scanning of the reading scanning unit is started with a delay of a predetermined time after detecting the on-edge of the generated detection signal, and the time when the leading edge of the transfer material reaches the photosensitive drum is detected after the on-edge of the detection signal is detected. A copier that controls the withdrawal of the registration shutter and the transfer of the transfer material by the registration roller so that the leading edge of the original image carried on the photosensitive drum reaches the transfer portion at the same time. Time t ₁ from when the on-edge of the detection signal is detected by making the rotation speed different from that of the registration roller
A copying machine comprising a control circuit for detecting an off edge after a lapse of time.

(2) The copying machine according to (1), wherein the coefficient of friction on the surface of the carry-out roller is different from the coefficient of friction on the surface of the registration roller.

(3) The copying machine according to (1), wherein the carry-out roller and the registration roller have different diameters.

By providing the configurations described in (1) to (3), it is possible to prevent erroneous detection of the trailing edge of the transfer material due to the bending of the transfer material, eliminate the malfunction of the resist shutter, and feed the paper. Since it can be controlled, the occurrence of transfer deviation can be prevented.

(4) A carry-out roller for feeding the transfer material fed from a plurality of paper feed paths toward the registration rollers,
A registration shutter and a registration sensor are provided in front of the registration roller in the sheet feeding direction, and after the on-edge of the detection signal generated from the registration sensor is detected, the scanning of the reading scanning unit is started with a delay of a predetermined time, and the detection is performed. The resist shutter is retracted so that the time when the front end of the transfer material reaches the photoconductor drum after the on-edge of the signal is detected coincides with the time when the front end of the original image carried on the photoconductor drum reaches the transfer portion. A copying machine controlled to be sent out by the registration rollers, comprising a control circuit that does not detect an on-edge until a time t _{2 has} elapsed after an off-edge of the detection signal was detected.

By providing the constitution (4),
It is possible to prevent erroneous detection of the transfer material due to chattering of the registration sensor.

(5) A copying machine provided with a control circuit for detecting an off edge of a detection signal sent from a paper discharge sensor provided in the fixing device, counting the off edge, and detecting the end of the set number of copies. The copying machine, wherein the control circuit detects the state of the output signal from the paper discharge sensor before the start of the copy operation and after the set number of copies is completed.

By providing the configuration mentioned in (5),
Regardless of the output waveform from the transfer material sensor and the passage timing of the transfer material sensor, it is possible to detect the transfer material remaining on the fixing device due to the feeding. In addition, this makes it possible to prevent the transfer material remaining in the fixing device from burning.

(6) A copying machine for controlling the timing of driving the main motor and the optical motor based on the output signals from the registration sensor and the paper discharge sensor arranged in the paper feed mechanism. The end of the set number is detected by counting the off edges of the sent detection signal,
A copying machine comprising a control circuit for controlling driving of the main motor when the set number of sheets is completed.

By providing the structure mentioned in (6),
The durability of the developer can be improved by reducing the driving time of the developing device per maintenance copy volume. Further, by providing the configuration described in (6), it is possible to reduce the driving time of the developing device in the intermittent copying of a small size, so that the durability of the developer can be improved. By providing the configuration described in (6), it is possible to reduce the driving time of the developing device even in the case of continuous copying of a small size, so that the durability of the developer can be improved.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a copying machine to which the present invention is applied will be described.

FIG. 1 is a schematic block diagram showing an embodiment of the copying apparatus of the present invention.

The copying apparatus according to this embodiment includes a reading / scanning unit 10, an image forming section 30, a paper feed mechanism 40, and a document placing section 5.
It consists of 0.

First, a normal copy operation of this image forming apparatus will be described.

Since the photosensitive drum 31 is rotated clockwise as shown by the arrow in FIG. 1 to perform pre-charge exposure, the charge is removed by the charge remover 36, and then the charge is given by the charger 32. Image exposure from the reading / scanning unit 10 forms an electrostatic latent image on the photosensitive drum 31 corresponding to the image of the original. After that, the electrostatic latent image on the photosensitive drum 31 is subjected to reversal development by the developer carried on the developing sleeve 33A to which the bias voltage of the developing device 33 is applied, and becomes a visible toner image.

On the other hand, the transfer material P of a specified size is carried out one by one from the paper feed cassette 41A or the paper feed cassette 41B loaded in the paper feed mechanism 40 by the carry-out roller 42A or the carry-out roller 42B, and the carry-out roller 43 and The sheet is fed toward the image transfer portion via the guide member 42. The transfer material P is sent onto the photosensitive drum 31 by the registration roller 44 which operates in synchronization with the toner image on the photosensitive drum 31. The toner image on the photoconductor drum 31 is transferred to the transfer material P by the action of the transfer device 34, separated from the photoconductor drum 31 by the charge removal action of the separator 35, and then fixed via the conveyor belt 45. Sent to vessel 37,
After being fused and fixed by the heating roller 37A and the pressure roller 37B, the sheet is discharged to the tray 54 outside the apparatus by the sheet discharge rollers 38 and 46.

The photoconductor drum 31 continues to rotate after the transfer material P is separated, and the toner remaining on the surface of the photoconductor drum 31 without being transferred is removed and cleaned by the cleaning blade 39A in pressure contact with the cleaning device 39, and the charge eliminator 36 is again removed.
After the charge is removed by, the electric charge is uniformly applied by the charger 32, and the next image forming process starts.

Next, a schematic structure of each member for executing the above-mentioned image forming process will be described.

The reading / scanning unit 10 includes an image forming section 30.
It is driven by an optical motor (not shown) separate from the main motor that drives the sheet feeding mechanism 40.

The reading / scanning unit 10 is provided with a document table 51 made of a transparent glass plate and a document placing section 50 having a document cover 52 for covering the document D placed on the document table 51. The first mirror unit 12, the second mirror unit 13, and
The imaging lens 14 and the reflection mirror 15 are included. Therefore, the image of the document D placed on the document table 51 is displayed by the illumination lamp 12
A first mirror unit 12 including A and a first mirror 12B
The parallel movement from the solid line to the position indicated by the broken line, and the first mirror unit 1 of the second mirror unit 13 that integrally includes the second mirror 13A and the third mirror 13B facing each other.
The entire surface is illuminated and scanned by the follow-up movement of 1/2 speed with respect to 2, and the image is reflected by the image pickup lens 14 through the first mirror 12B, the second mirror 13A, the third mirror 13B and the reflection mirror 15, and the photosensitive member. An image is formed on the drum 31. When scanning is completed, the first mirror unit 12 and the second mirror unit 13 return to their original positions, and stand by until the next image formation.

As shown in FIG. 1, the image forming section 30 comprises a photosensitive drum 31, a charging device 32, a developing device 33, a transferring device 34, a separator 35, a cleaning device 39, a discharging device 36 and a fixing device 37. .

The photosensitive drum 31 is an OP which is negatively charged.
C is a drum coated with a photoconductor, and its rotary shaft is provided with an encoder (not shown). The phase signal from this encoder is sent to the CPU 90 and used for process control that requires accurate knowledge of the image position.

The charger 32 is, for example, a scorotron charger, which prevents fog by uniformly charging the photosensitive drum 31 to a predetermined voltage and adjusting gradation reproducibility before the latent image forming process. .

The developing device 33 stirs the developer in which the toner and the carrier are controlled to have a predetermined concentration (weight%).
After stirring at C, a magnetic brush is formed on the outer circumference of the developing sleeve 33A that rotates outside the magnet roller, and a predetermined bias voltage is applied to the developing sleeve 33A to cause the latent image in the developing area facing the photoconductor drum 31. The image is visualized as a toner image.

In the developing device 33, a rotating shaft of a magnet roller covered with a developing sleeve 33A is fitted in a side wall of the housing in the vicinity of an opening facing the photosensitive drum 31, and a drive shaft of a stirring screw 33C is provided behind it. The drive shafts of the developing sleeve 33A and the stirring screw 33C, which are fitted into the side wall of the housing, can be connected to a drive system (not shown) via, for example, gears to change the rotational speed. There is. This control operation is performed by the CPU 90.

The magnetic permeability sensor TS provided at the bottom of the agitating screw 33C of the developing device 33 utilizes the fact that the magnetic permeability changes when the toner concentration of the developer changes, and thus the developing device 33 is used.
It is a sensor that monitors the toner concentration of the developer inside and sends the toner concentration information of the developer to the CPU 90. CPU 90
When the toner concentration decreases below a certain value based on the information of the magnetic permeability sensor TS, the toner replenishment instruction is sent to the toner replenishing unit (not shown) to replenish the toner, so that the toner concentration of the developer is always kept constant. can do.

The developer used is a two-component developer consisting of a polyester-based toner having a weight average particle diameter of 8.5 μm and a carrier having a resin coating on ferrite and a weight average particle diameter of 60 μm, and having a toner concentration of 6 to 9%. Therefore, the toner density variation is controlled to be within ± 0.3% by controlling the toner density.

As is well known, the transfer device 34 superimposes the transfer material P on the toner image electrostatically carried on the photosensitive drum 31,
The toner is transferred onto the transfer material P by discharging the electric charge from the back side of the transfer material P, and a scorotron discharger is preferable, but not limited to this, and a corotron charger or a charging device is used. Any material that electrostatically transfers the toner image onto the transfer material P such as a roller may be used.

As is well known, the separator 35 is the photosensitive drum 3
The transfer material P is separated by removing the charge from the transfer material P that is electrostatically adsorbed on 1.

The cleaning device 30 scrapes off the toner and dust adhering to the surface of the photosensitive drum 31 by bringing a blade or the like into contact with the surface of the photosensitive drum 31, and captures the toner and dust in the waste toner box.

As is well known, the fixing device 37 is a device for permanently fixing the toner image on the transfer material by applying heat or heat and pressure to the transfer material carrying the toner image. The fixing device 37 constitutes the image forming unit 30, but since it is also a part of the paper feeding mechanism, it will be described with reference to FIGS. 4 and 5.

FIG. 4 is a perspective view of a main part of the fixing device, and FIG.
FIG. 3 is a cross-sectional view of the fixing device.

As shown in FIGS. 4 and 5, the fixing device 37 includes a fixing roller 1, a pressure roller 2, a guide 3 for guiding the transfer material P between the rollers 1 and 2, and a transfer material P wound around the roller. It includes separation claws 4 and 5 for preventing and discharge rollers 6 and 7 for sending the transfer material P.

The fixing roller 1 has a surface layer made of a material such as Teflon, a heater 13 as a heating source is built in the center thereof, and the temperature detector 12 detects the surface temperature of the fixing roller 1. It is controlled so that it is always constant. The fixing roller 1 is coated with a release agent for preventing the unfixed toner N on the transfer material P from being offset, and a long cleaning web 8 for removing the offset toner when the offset occurs. Are arranged so as to rub against each other. The cleaning web 8 is stretched over shafts 9 and 10 that rotate at a very low speed, and the porous rubber roller 1 is used.
1, the fixing roller 1 is pressed against the fixing roller 1 with an appropriate pressure. The temperature detector 12 is composed of a thermistor or the like, and detects the surface temperature of the fixing roller 1 to turn on / off the heater 13 for heating the fixing roller 1. The pressure roller 2 has a surface layer such as rubber. The temperature protector 14 melts and fuses when the fixing roller 1 reaches an abnormally high temperature.
To stop the power supply to.

As shown in FIG. 1, the cleaning device 39 presses the cleaning blade 39A against the surface of the photosensitive drum 31 which further rotates after the transfer process, and removes and cleans the residual toner by the cleaning blade 39A.

The static eliminator 36 removes static electricity from the photosensitive drum 31 after the cleaning process.

The above is the schematic configuration of the document placing section 50, the reading / scanning unit 10, and the image forming section 30.

Next, the schematic structure of the paper feed mechanism 40 will be described with reference to FIGS. 1, 2 and 3.

FIG. 2 is a side view showing the main part of the paper feed mechanism of the copying apparatus of this embodiment, and FIG. 3 is a view showing the structure of the main part of the transfer material detection sensor of this embodiment. Yes, Figure 3
3A is a cross-sectional view, and FIG. 3B is a plan view.

The paper feeding mechanism 40 feeds the transfer material P to the transfer portion so as to register with the toner image carried on the photosensitive drum 31, and discharges it from the fixing device 37.
As shown in FIG.
Carry-out rollers 42A and 42B, guide members 42, carry-out rollers 43, registration rollers 44, paper feed cassettes 41A and 41B, manual paper feed table 53, and manual paper feed table 50. Ejection of the resist shutter 25, the transfer material detection sensor 20, and the fixing device 37 arranged between the carry-out roller 43 and the registration roller 44, where the guide member 42, which is the paper feed path, is gathered from the paper feed cassettes 41A and 41B. It comprises a paper discharge sensor 70 for jam detection which is arranged in front of the rollers 6 and 7 as shown in FIG.

In the sheet feeding mechanism 40 of this embodiment, the friction coefficient of the surface of the registration roller 44 and the friction coefficient of the surface of the carry-out roller 43 are changed in order to correct the bending of the transfer material P described above. The surface of the registration roller 44 is surface-treated to increase the coefficient of friction. Therefore, the coefficient of friction of the registration roller 44 is larger than that of the carry-out roller 43. With this configuration, even if the transfer material P bends between the registration roller 44 and the carry-out roller 43, the transfer material P is corrected from the difference in the transport speed.

Even if the registration roller 44 and the carry-out roller 43 have the same friction coefficient, the flexure correction function has a function that the carry-out roller 43 has a rotational speed higher than that of the register roller 44.
Even if the number of rotations is reduced, the same effect can be obtained. Further, even if the diameter of the registration roller 44 is made larger than the diameter of the carry-out roller 43 and the friction coefficients of both roller surfaces are the same, the same effect as described above can be obtained.

As shown in FIG. 2, the resist shutter 25 projects from the guide member 42 by the excitation operation of the solenoid S1 and stops the feeding of the transfer material P. As a result, the skew of the transfer material P is corrected to ensure the registration with the toner image carried on the photosensitive drum 31.

The transfer material detection sensor 20 is a registration sensor provided between the registration roller 44 and the carry-out roller as shown in FIG. Hereinafter, this is referred to as the registration sensor 20. The transfer material detection sensor 20 includes an actuator 21 and a photocoupler 22 as shown in FIG. The actuator 21 is rotatably supported by a shaft 21a, and the transfer material P
When it passes, it rotates in the direction shown by the dotted line. This allows
The optical path of the photo coupler 22 is blocked. Therefore, the photocoupler 22 turns on / off the output depending on whether or not the transfer material P has passed. Therefore, the CPU 90 controls the resist shutter 25 to project from the guide member 42 by the output signal from the transfer material detection sensor 20.

The paper feed cassettes 41A and 41B are universal cassettes that can store the transfer materials P of various sizes.
The paper feed cassettes 41A and 41B do not include a size detection unit for detecting the transfer material size.

The paper feed mechanism 40 having the above-described structure carries out the transfer material P of the designated size one by one from the paper feed cassettes 41A and 41B by the carry-out rollers 42A and 42B, and carries out the carry-out roller 43 and the guide member. The paper is fed toward the image transfer unit via 42. Transfer material P fed
Is sent onto the photosensitive drum 31 by the registration roller 44 which operates in synchronization with the toner image on the photosensitive drum 31. By the action of the transfer device 34, the transfer material P is
The toner image on the photosensitive drum 31 is transferred to the separator 35.
After being separated from the photosensitive drum 31 by the discharging action of the sheet, the sheet is sent to the fixing device 37 via the conveyor belt 45, and is fused and fixed by the heating roller 37A and the pressure roller 37B, and then the sheet is discharged by the sheet discharge rollers 38 and 46. Outside tray 5
It is discharged to 4.

With the configuration described above, the transfer material P is fed along the guide 3 from the left side in FIG. 5 at the time of fixing. The unfixed toner is heated and fixed on the transfer material P in the process of passing between the rollers 1 and 2. Thereafter, the transfer material P is sent out by the discharge rollers 6 and 7 while being prevented from being wound around the rollers by the separation claws 4 and 5. The above is the schematic configuration of the paper feed mechanism 40.

Next, the schematic structure of the control circuit of the copying machine of this embodiment will be described with reference to FIG.

FIG. 6 is a block diagram showing the control circuit of this embodiment.

The CPU 90 controls the entire control relating to the electrophotographic process, but in FIG.
The configuration relating to the control is mainly shown, and the registration control system 23, the fixing temperature control system 19, the paper discharge control system 71, the motor driver 80, and the solenoids S1 and S2 are connected.
The CPU 90 detects the leading edge of the transfer material P at the on edges of the pulse signals sent from the registration sensor 20 and the paper discharge sensor 70, and detects the transfer material P from the off edges of the pulse signals sent from the registration sensor 20 and the paper discharge sensor 70. The rear end is detected. The CPU 90 counts the maintenance copy volume by counting the off edges of the pulse signal sent from the paper discharge sensor 70,
Alternatively, the number of copies set from the operation panel (not shown) is counted. The CPU 90 stops the drive of the main motor M when the number of copies set on the operation panel (not shown) is reached by counting the off edges of the pulse signal sent from the paper discharge sensor 70.

The motor driver 80 drives the main motor M and an optical motor (not shown). The main motor M includes the rollers 43 and 4 that constitute the paper feeding mechanism 40.
4 and the like, the developing sleeve 33A of the developing device 33, the stirring screw 33C, the fixing roller 1 of the fixing device 37, and the like, and are the driving sources of all members other than the reading and scanning unit 10. In this embodiment, the CPU 90 independently controls the drive of the main motor M and the optical motor (not shown) via the motor driver 80.

Solenoids S2 and S3 are output rollers 42.
A and 42B are attached to and detached from the drive system, and the solenoid S1 drives the registration shutter 25.

The resist control system 23 uses the inverting circuit INV1,
INV2, resistance elements R1 to R4, and light emitting diode LED
It is composed of a phototransistor Tr1, an LED driving transistor Tr2 and a power supply. Resist control system 2
3 is connected to the output port PO of the CPU 90 that controls the LED and the input port of the CPU 90 that monitors the output of the phototransistor Tr1. The CPU 90 outputs a low level from the output port PO. As a result, the inverting circuit I
The transistor Tr2 is driven by the base current control resistor R1 and the base-emitter resistor R2 via NV1. As a result, the LED is energized via the resistor R4 and starts emitting light. The light from the LED1 is incident on the phototransistor Tr1 and passes through the collector resistor R3 to the inverting circuit INV2.
Is input to the CPU 90 as a low level signal.
Therefore, the CPU 90 controls the transfer material P from the registration control system 23.
When detecting the off-edge detecting the tip of the, the resist shutter 25 is housed according to the above-described predetermined sequence,
The internal timer is started, and the transport distance length L (mm) from the registration sensor 20 to the paper discharge sensor 70 and the transport speed S
(L / S) sec is the time required to reach the paper discharge sensor 70 from the registration sensor 20 from (mm / sec).
Is calculated, and after the timer starts (L ÷ S-α) sec
Count. If it is not detected that the transfer material P arrives at the paper discharge sensor 70 even after this time has elapsed, the CPU 9
Judge as a jam by 0.

The CPU 90 detects the transfer material P, and then determines the transfer material length Y (mm) according to the time T required for the transfer material P to pass the registration sensor 20 and the transport speed S (mm / sec) (T × S). ) Mm is selected to select a standard size that is closest to the length of the transfer material _P and is determined as the actual transfer material length Y _P. Note that α is a time in which a margin is taken into consideration by the device performance.

The paper discharge sensor 70 is connected to the CPU 90 as a paper discharge control system 71 shown in FIG. This also detects the transfer material P with the same configuration as the registration control system 23. After discharge sensor 70 detects the interruption of the light passage of the leading edge of the transfer material P, the actual transfer material after the length Y _P content of time calculated at the time of registration sensor passes also the passage of the trailing edge of the transfer material P When it is not detected by the incidence of light, the CPU 90 determines that there is a jam.

The fixing temperature control system 19 comprises a heater 13, a temperature protector 14, a solid state relay 15, and a heater power supply 17. The heater power source 17, the temperature protector 14, the heater 13, and the SSR 15 are connected in series, and are connected to the A / D conversion processing input port and the driving port OUT1 of the SSR 15.

FIG. 7 is a time chart showing a pulse signal sent from the registration sensor.

FIG. 7A shows the output from the registration sensor when the A4 size transfer material P is normally conveyed. The low level indicates a state in which the actuator is not biased by the transfer material P, and the high level indicates the transfer material P.
Shows the state where the actuator is energized. The on-edge is an edge that is displaced from a low level to a high level, and the off-edge is an edge that is displaced from a high level to a low level. t _s represents the minimum transfer material interval, and is a value set for each model in order to obtain a predetermined CPM.

FIG. 7 (b) shows the output from the registration sensor when the transfer material P of the minimum size is normally conveyed.

FIG. 7C is a time chart showing a drive signal given to the solenoid S1 for driving the resist shutter. The high level indicates the time during which the resist shutter 25 is raised from the transport guide 42 and is waiting for the transfer material P to arrive, and the low level indicates the resist shutter 2.
5 shows a period during which the transport guide 5 is retracted to the transport guide 42.
Therefore, the CPU 90 displaces the solenoid drive signal from the high level to the low level after a lapse of a predetermined time t _R from the time t _ON of the occurrence of the on edge shown in FIG. 7A. This indicates that the registration shutter 25 is retracted from the transport guide 42 and the waiting period is ended.

FIG. 7D shows the time when a part of the high level of the pulse output from the resist sensor 20 changes to the low level due to the bending of the transfer material P described with reference to FIG. It is a chart. 7 (c ') is shown in FIG.
(D) shows that the drive signal of the solenoid S1 for driving the resist shutter changes. CP
According to the conventional control method, the U90 turns on such a pulse signal after t _R from the off edge of the registration sensor 20, causing a malfunction. Here, t _L is the time required to pass through the interval between the registration roller 44 and the carry-out roller 43 at a predetermined transport speed, and according to the experiment by the applicant of the present invention, the registration roller 44 and the carry-out roller 43 take half the time t _L. It was found that the deflection correction function of worked. t _P represents the time until the transfer material _P of the minimum size passes. Therefore, the CPU 90 does not detect the off-edge of the output signal from the registration sensor 20 for a predetermined time t ₁ after detecting the on-edge from the registration sensor 20.
As a result, the CPU 90 can prevent malfunction due to the bending of the transfer material P. The predetermined time t ₁ is t _R + t ₀ +
It is longer than ½ × t _L and shorter than t _P.
Here, t ₀ is the time required for the transfer material P to reach the registration roller 44 from the registration shutter 25.

FIG. 7E is a time chart showing a pulse output from the resist sensor 20 for the chattering phenomenon described with reference to FIG. A pulse due to chattering occurs within the time period t _s . According to an experiment by the applicant, it has been confirmed that the period of the pulse due to chattering is constant regardless of the size of the transfer material P. The time t _a is the time required for returning to the photocoupler again due to a reaction when the actuator of the registration sensor 20 returns, and then returning to the photocoupler again. Therefore, the CPU 90 does not detect the on-edge in the period t ₂ after detecting the off-edge from the registration sensor 20. This is t
It indicates that the process for detecting the on-edge is executed after the lapse of ₂ . Such a time t ₂ is longer than t _a,
t ₂ is shorter than the time t _s at which the leading edge of the subsequent transfer material P can be detected.

As described above, the CPU 90 can prevent malfunction of the registration sensor 20 and malfunction of the registration shutter 25 due to chattering as described above.

Further, the CPU 90 can prevent erroneous detection of the trailing edge of the transfer material due to the bending of the transfer material P, eliminate erroneous operation of the resist shutter, and control paper feeding to prevent occurrence of transfer deviation. can do.

The CPU 90 can prevent erroneous detection of the transfer material P due to chattering of the registration sensor 20 as described above. Next, the operation state of the fixing device 27 will be described.

FIG. 8 is a time chart showing the input / output signals of the respective parts of the fixing device when the paper is fed.

FIG. 8A is a time chart showing the drive time of the main motor M, showing three consecutive copies. A low level indicates a stop, and a high level indicates a rotating state.

FIG. 8B shows a pulse signal output from the paper discharge sensor 70. The high level indicates that the transfer material P exists in the paper discharge sensor 70, and the low level indicates. It is shown that the transfer material P does not exist in the paper discharge sensor 70. Therefore, it is shown that the transfer material P is present in the paper discharge sensor 70 after the three transfer materials P successively pass through the paper discharge sensor 70. Conventionally, since the fixing heater 13 is not turned off in such a state, there is a risk of burning.

FIG. 8C shows the paper discharge sensor 70 of the CPU 90.
5 is a time chart showing a reference operation of an output signal from the. The CPU 90 shows the timing of detecting the output state from the paper discharge sensor 70 before and after the start of the copy operation. The CPU 90 indicates that the residual transfer material P is detected at time t ₁₀ . It should be noted that the CPU 90 detects off-edges from the set number of sheet discharge sensors 90 in order to detect a jam during the copy operation. Such CPU
The operation of 90 is omitted from FIG.

FIG. 8D is a time chart showing the driving state of the fixing heater 13. The high level shows the drive state of the fixing heater 13, and the low level shows the stop state of the fixing heater 13. The CPU 90 indicates that the fixing heater is stopped at time t ₁₀ when the residual transfer material P is detected.

FIG. 9 is a flow chart showing the control operation of the fixing temperature control section.

The CPU 90 performs a control sequence other than temperature control (step 1), and thereafter detects the presence of the transfer material P (step 2).

If the CPU 90 detects the presence of the transfer material in step 2, it sends a control signal to turn off the SSR 15 (step 3), and if it does not detect the presence of the transfer material in step 2, the process proceeds to step 5. Further, the CPU 90 executes the operation of turning off the SSR 15 in step 3, and then executes the abnormality processing in step 4. That is, the rotation of the fixing roller 1 is stopped and the paper jam lamp is turned on.

The CPU 90 receives a signal from the temperature detector 12 in step 5, sends an off command to the SSR 15 in step 7 when the fixing roller has reached the specified temperature, and has not reached the specified temperature in step 5. In this case, the ON command is sent to the SSR 15 in step 6. It should be noted that after the operation is completed in steps 6 and 7, the state returns to the start state.

As described above, the CPU 90 can detect the residual of the transfer material P on the fixing device 37 due to the feeding, regardless of the output waveform from the registration sensor 20 and the passage timing of the registration sensor 20, as described above. It is possible to prevent the transfer material P remaining in the fixing device 37 from burning.

FIG. 10 is a time chart showing the driving states of the optical motor and the main motor.

FIG. 10A shows the driving time of the entire copying machine of this embodiment. The high level is the total time for obtaining one copy, and the high level is the intermittent time when no copy processing is performed. It's time. FIG. 10B is a time chart showing the drive state of the optical motor, where the high level shows the drive state and the low level shows the stop state. FIG. 10C is a time chart showing the output signal from the paper discharge sensor 70. The high level shows that the transfer material P is passing, and the low level shows the state where the transfer material P does not exist. It is a thing. FIG. 10D is a time chart showing the drive state of the main motor M, where the high level shows the drive state and the low level shows the stop state.

According to such a time chart, the CPU 90
Indicates that the drive of the main motor M is stopped when the off-edge from the paper discharge sensor 90 is detected.
As a result, the copying machine of the present embodiment can improve the durability of the developer by reducing the drive time of the developing device 33 per maintenance copy volume.

Further, the copying machine of this embodiment can improve the durability of the developer by reducing the driving time of the developing device during the intermittent copying of a small size.

Furthermore, in the copying machine of this embodiment, the durability of the developer can be improved by reducing the driving time of the developing device even in the case of continuous copying of small size.

[0096]

According to the first to third aspects of the present invention, by providing the above configuration, the malfunction of the resist shutter due to the false detection of the trailing edge of the transfer material due to the bending of the transfer material can be eliminated. It was possible to provide a copying machine capable of controlling the paper feed and preventing the occurrence of transfer deviation.

The invention according to claim 4 is able to provide a copying machine which is provided with the above configuration and which can prevent erroneous detection of the transfer material due to chattering of the registration sensor.

According to the fifth aspect of the present invention, by virtue of the above configuration, it is possible to detect the transfer material remaining on the fixing device due to the feeding regardless of the output waveform from the transfer material sensor and the passage timing of the transfer material sensor. You can do this,
It was possible to provide a copying machine capable of preventing the transfer material remaining in the fixing device from burning.

According to the sixth aspect of the present invention, by providing the above-described structure, a copying machine capable of improving the durability of the developer by reducing the driving time of the developing unit per maintenance copy volume is provided. I was able to. The invention according to claim 4 is able to provide a copying machine which is provided with the above-mentioned configuration and which can reduce the driving time of the developing device and improve the durability of the developer in the intermittent copying of a small size. According to the invention described in claim 4, by providing the above configuration, it is possible to provide a copying machine capable of reducing the driving time of the developing device and improving the durability of the developer even in the case of continuous copying of a small size. .

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a copying apparatus of the present invention.

FIG. 2 is a side view showing a main part of a paper feed mechanism of the copying apparatus of this embodiment.

FIG. 3 is a diagram showing a main configuration of a transfer material detection sensor according to the present embodiment.

FIG. 4 is a perspective view of a main part of the fixing device.

FIG. 5 is a cross-sectional view of a fixing device.

FIG. 6 is a block diagram showing a control circuit of this embodiment.

FIG. 7 is a time chart showing a pulse signal sent from a registration sensor.

FIG. 8 is a time chart showing an input / output signal of each part of the fixing device when the paper is fed.

FIG. 9 is a flowchart showing a control operation of a fixing temperature control section.

FIG. 10 is a time chart showing driving states of an optical motor and a main motor.

FIG. 11 is a diagram showing transfer deviation due to erroneous detection of the trailing edge of the transfer material due to bending of the transfer material.

FIG. 12 is a schematic diagram showing erroneous detection of a transfer material due to chattering of an actuator forming a registration sensor.

[Explanation of symbols]

 10 Reading / scanning Unit 20 Registration Sensor 25 Registration Shutter 31 Photoreceptor Drum 44 Registration Roller 43 Discharge Roller 90 Control Circuit

Claims (6)

[Claims] 1. A carry-out roller for feeding transfer materials fed from a plurality of paper feed paths toward a registration roller, and a registration shutter and a registration sensor provided in front of the registration roller in the paper feeding direction. When the scanning of the reading scanning unit is started with a delay of a predetermined time after detecting the on-edge of the detection signal generated from the sensor, and when the leading edge of the transfer material reaches the photosensitive drum after the on-edge of the detection signal is detected. In a copying machine that controls to retract the resist shutter and send out the transfer material by the registration roller so that the front end of the original image carried on the photosensitive drum reaches the transfer portion at the same time,
A copying machine comprising a control circuit that makes the rotation speeds of the carry-out roller and the registration roller different from each other, and detects an off-edge after a lapse of time t ₁ after detecting an on-edge of the detection signal. 2. The copying machine according to claim 1, wherein the coefficient of friction on the surface of the carry-out roller and the coefficient of friction on the surface of the registration roller are different. 3. The copying machine according to claim 1, wherein the carry-out roller and the registration roller have different diameters. 4. A carry-out roller for feeding transfer material fed from a plurality of paper feed paths toward a registration roller, and a registration shutter and a registration sensor before the registration roller in the paper feeding direction. When the scanning of the reading scanning unit is started with a delay of a predetermined time after detecting the on-edge of the detection signal generated from the sensor, and when the leading edge of the transfer material reaches the photosensitive drum after the on-edge of the detection signal is detected. An off-edge of the detection signal is detected in a copying machine in which the registration shutter is retracted and the registration roller feeds the original image carried on the photoconductor drum at the time when the leading edge of the original image reaches the transfer portion. A copying machine comprising a control circuit that does not detect an on-edge until after a time t _{2 has} elapsed. 5. A copying machine provided with a control circuit for detecting an off edge of a detection signal sent from a paper discharge sensor provided in a fixing device, counting the off edge, and detecting the end of a set number of copies. The copying machine is characterized in that the circuit detects the state of the output signal from the paper ejection sensor before the start of the copy operation and after the end of the set number of copies. 6. A copying machine, which controls the timing of driving a main motor and an optical motor based on output signals from a registration sensor and a paper discharge sensor arranged in a paper feed mechanism, sends out from the paper discharge sensor. A copying machine comprising a control circuit for counting the number of off-edges of a detection signal to detect the end of a set number of sheets, and controlling the driving of the main motor by the end of the set number of sheets.