JPS647384B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic copying machine provided with means for removing optical memory generated on a photoreceptor for forming an image.

Conventionally, in electrophotographic copying machines, it is necessary to perform various operations such as when copying paper jams, when cleaning areas contaminated with developer, etc., or when replacing or repairing photoreceptors and other consumable parts.
I had to open the front door of the copying machine and reach inside to treat the problem. Alternatively, it has sometimes been necessary to remove the rear or upper exterior, and sometimes even unrelated parts within the main body. Therefore, recently, a copying machine has appeared in which the main body can be separated vertically from one end along the copying machine feeding/conveying path, and it has become possible to considerably alleviate the above-mentioned difficulties.

However, since separation is possible in this manner, the photoreceptor is exposed to external light during separation, resulting in a large change in the characteristics of the portion of the photoreceptor exposed to the light. Therefore, when the separated upper and lower parts of the copying machine main body are closed again and a copy is made, an optical memory effect occurs, causing problems. For example, because not enough charge is placed on the photoreceptor, the first few copies may show white areas corresponding to the photoreceptor parts exposed to external light, or the colors of the formed images may become pale. There will be negative effects.

In particular, when a user encounters a paper jam, separates the top and bottom of such a copying machine, removes the jammed paper, closes it again, and makes a copy, the user is unable to output blank copy paper. I must say that this is extremely inconvenient for them.

In view of the above-mentioned drawbacks, the present invention has been proposed to separate the copying machine body substantially along the paper transport path, and in connection with this operation, remove the optical memory of the photoreceptor caused by exposure to external light. An object of the present invention is to provide an electrophotographic copying machine, which is equipped with a means for removing optical memory, and in which the optical memory removing means is driven in accordance with temperature detection of a heat fixing device.

As mentioned above, the photoreceptor is exposed to external light mainly when the upper and lower parts of the main body are separated and opened due to a paper jam or maintenance, and therefore, the photoreceptor is exposed to external light when the upper and lower parts of the main body are separated and opened. It is only necessary to activate the optical memory removing means. When separating the top and bottom of a copying machine, power supply to the main parts inside the copying machine is generally stopped for safety reasons. Therefore, according to the present invention, when the vertical separation of the copying machine main body is detected, the removal means for removing the optical memory is driven when power is resupplied to the copying machine main body. In particular, the power switch is connected in series with a door switch, etc. for opening the main body of the copying machine vertically, so the door switch opens in connection with the vertical separation, and in response, some parts are opened for safety. The power supply will be cut off.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a cross-sectional view schematically showing a copying machine according to the present invention, and FIG. 2 is an external view showing the main body of the copying machine separated into upper and lower parts. In the figure, reference numeral 1 denotes a drum-shaped photoreceptor that is rotationally driven in the direction of the arrow. On the circumferential surface of the photoreceptor 1, various copying processes for image formation are arranged facing each other. Reference numeral 2 denotes a corona charger for uniformly charging a photoreceptor disposed facing around the rotating circumference of the photoreceptor 1; 3 a corona charger for exposing an image of an original 5 on an original platen 4 to the uniformly charged surface of the photoreceptor; 6 is an illumination device that illuminates the original 5; 7 is a developing device that visualizes the electrostatic latent image formed on the surface of the photoreceptor 1 as a toner image after image exposure; 8 is a system that a corona charger for electrostatically transferring the toner image onto the copy paper 9 sent by the
Reference numeral 10 indicates a corona charger for removing charges remaining on the photoreceptor 1, and reference numeral 11 indicates an optical charge remover using a lamp. In the copying machine shown in FIG. 1, the developing device 7 also serves as a cleaning device to remove toner remaining on the surface of the photoreceptor. Also, 1
2 is a heat fixing roller for fixing the toner image on the copy paper 9, and 13 is a discharge roller for discharging the copy paper 9 after fixing.

In the copying machine shown in FIG. 1, an upper part 15 and a lower part 16 are separated from each other about a support shaft 14 on the paper feed side in order to separate the copy paper 9 into upper and lower parts along the conveying path (the part indicated by the dotted line). It is configured so that it can be rotated against. Various copying processes provided around the photoreceptor 1 are attached to the upper part 15, and only a corona charger for transfer is attached to the lower part 16 side. In this case, upper and lower rollers of the conveyance system are provided respectively. A spring 17 is attached between the upper part 15 and the lower part 16 of the copying machine body, and the upper part 15 is connected to the support shaft 14.
It is always urged upwards with the center at . Also, the upper part 15
is fixed to the lower part 16 by a locking member 18 provided on the upper part 15 being locked with a locking member (not shown) provided in the lower part 16. In other words,
When the locking member 18 is released, the upper portion 15 is opened by the biasing force of the spring 17 as shown in FIG. At this time, a part 1a of the photoreceptor 1 attached to the upper part 15 is exposed to external light 19, and optical memory is generated in that part.

In addition, 20 in the figure is a detection micro switch for detecting opening/closing of the upper part 15 of the copying machine main body, and when the upper part 15 changes from the closed state to the open state and then to the closed state again, the copying machine is separated into the upper and lower parts. This is to detect when something has happened. This micro switch 20
is attached to the lower part 16 main body side. Further, numeral 21 is a power switch, and 22 is a door switch. The door switch 22 changes from a closed state to an open state when the exterior of the copying machine (not shown) is removed, and detects the state in which the exterior of the copying machine is removed.This allows the power supply to be switched off for safety. Cut off. Moreover, the exterior is removed, for example, when opening the upper part 15.

Generally, a copying machine uses the same driving source to maintain a synchronous relationship between the conveyance speed of the copy paper 9 and the rotational speed of the photoconductor 1. This is a configuration in which both are driven. Therefore, the same drive source as that for driving the copy paper conveyance means is used to drive the heat fixing roller 12 disposed in the conveyance path of the copy paper 9. Therefore, when the main motor that drives the photoreceptor 1 and the like is rotated, the fixing roller 12 is also rotated at the same time. Therefore, the heat fixing roller 12 does not require a transmission clutch or the like for rotation control and is directly connected to the main motor. The above-mentioned transport system also has a similar configuration.

Next, a specific example of optical memory removal according to the present invention in the copying machine configured as described above will be described in detail. First, the copying operation of the copying machine of the present invention will be explained. When you press the copy switch, photoconductor 1
starts rotating. A synchronization disk 23 in which a slit for synchronization is formed is provided on the same axis of the photoconductor 1. Upon receiving a signal from the synchronization disk 23, the copy control circuit sequentially transfers data to the photoconductor 1. The various copying processes (image forming means) for repeatedly forming images are driven and controlled. This copy control circuit is
This is a conventionally well-known device that sequentially controls a copying machine. First, the corona charger 2 is driven to sequentially and uniformly charge the photoreceptor 1. When the image forming start tip of the photoconductor 1 reaches the exposure start position, the document table 4 starts moving, and at the same time the photoconductor 1
Image exposure is then performed via the optical system 3. Next, the latent image formed by the image exposure is visualized as a toner image when it reaches the position of the developing device 7, and is transferred onto the copying paper 9 fed through the conveying system by the action of the copying corona charger 8. The toner image is transferred.
After this transfer, the photoreceptor 1 is charged with a corona charger 10 for charge removal.
The remaining charge is removed by a photostatic eliminator 11, and the photostatic charge is further removed by a photostatic eliminator 11. Then, when the photoreceptor 1 passes through the corona charger 2, if it reaches the developing device 7 without being corona charged and without being subjected to image exposure, residual toner is removed and the photoreceptor 1 is prepared for the next image formation. In other words, one copy is made by the photoreceptor 1 rotating twice.

On the other hand, the copy paper on which the toner image has been transferred is peeled off from the photoreceptor 1, passes through a heat fixing roller 12, is fixed, and is discharged from the copying machine via a paper discharge roller 13. During the copying operation described above, the copy paper 9
If paper is jammed in the conveyance path, the upper part 15 of the copying machine main body is released from the lower part 16 by releasing the locking member 18, and the jammed paper is removed. In this case, since the copying machine main body upper part 15 is separated along the conveyance system, it can be easily removed. After this removal, the upper part of the copier main body 1
5 to the lower part 16. In this case, when the upper part 15 is opened, the part 1a of the photoreceptor 1 is irradiated with the external light 19, and in order to remove this optical memory, the copying machine main body is separated from the top and bottom from the closed state to the open state and from the open state. According to the present invention, the optical memory removing means is driven in response to the detection operation by the detection switch 20 that detects a change in the temperature of the fixing roller 12.

Next, the optical memory removing device for the photoreceptor 1 will be described in detail. Particularly, in the present invention, the thermal fixing roller 12 is driven by the rotation of the photoreceptor 1, and the optical memory removal device is driven by detecting that the thermal fixing roller 12 reaches a temperature slightly lower than the set temperature.
This is done in view of the fact that the heat fixing roller 12 reaches the set temperature after the optical memory is removed.

FIG. 3 is a diagram showing a specific example of the drive circuit of the optical memory removal device. The apparatus of the present invention drives each copying process to remove the optical memory. In other words, the synchronizing disk 23 is used, and each copying process described above is driven by signals from the disk 23. As shown in FIG. 4, the synchronous disk 23 has seven slits Pa- ₀ to Pa- ₆ formed therein, and the slits are detected by a detector consisting of a light emitting diode 24 and a phototransistor 25. In addition, synchronous disk 23
is shown without the slit for copying. In the synchronization disk 23, the position of the slit Pa- ₀ corresponds to the start position (standby position) of the photoreceptor 1, and determines the tip of the photoreceptor at which image formation starts.

In the circuit diagram of FIG. 3, the emitter output of the phototransistor 25 is supplied to a one-shot multivibrator (hereinafter referred to as MB) 26 and is also supplied to one input terminal of an AND gate 27. The other input terminal of AND gate 27 is
The output of MB26 is supplied. When the MB26 receives the slit signal PA from the synchronous disk 23, its output becomes "H" for a certain period of time _.
The time is set to be slightly longer than the period t during which PA- ₀ is output. In other words, slit Pa- ₆
The starting position of the photoreceptor 1 is detected by making the distance between Pa- 0 and Pa- ₀ close to each other. Therefore, when the signal PA- ₀ of the slit Pa- ₀ is detected while the output of the MB26 is "H", the AND gate 27 opens and outputs the signal SPS indicating the starting position of the photoconductor via the inverter 28. do. The flip-flop 29 is connected to the reset terminal R side of the flip-flop 29 via a series circuit including a close detection switch 20, a resistor R, and the like to a DC power supply +V whose supply is interrupted by opening and closing of the power switch 21. Further, one end of the resistor R is grounded via a capacitor C.

Then, the power switch 21 and the door switch 22
If either of the detection switches 20 and 20 is opened and the resistor R is left without power +V, an internal resistance (not shown) between the reset terminal of the flip-flop 29 and ground causes the capacitor to close. The charge accumulated in C is discharged, and the voltage at the reset terminal of flip-flop 29 becomes "L". Then, when the power switch 21, door switch 22, and detection switch 20 are all closed, power +V is supplied to the circuit of the resistor and capacitor C, and the voltage between the terminals of the capacitor gradually shifts to "H".

Therefore, the set terminal S of flip-flop 29
is supplied with the signal SPS from the inverter 28, and until this signal becomes "L", the set output Q (IRA signal) of the flip-flop 29 is
The "L" state will be maintained. The flip-flop 29 and the following flip-flops are set or reset when an "L" signal is supplied to each input terminal.

Further, the output of the AND gate 27 is supplied to one input terminal of a NAND gate 30, and the output terminals A and C of a binary counter (hereinafter referred to as a counter) 31 are supplied to the other input terminal of the NAND gate 30. The output of a NAND gate 32 that inputs a signal is supplied. The counter 31 is a counter that is reset when the initial reset signal IRA is "L", and counts up by one when the output from the NAND gate 30 is "L". In other words,
The counter 31 counts every time the signal SPS is output. Therefore, when the counter 31 counts "5", the output terminals A and C become "H",
The output of the NAND gate 32 is inverted to "L" and subsequent counting is stopped. nand gate 32
The output of the inverter 33 becomes the signal ISB. This signal ISB is a signal obtained by counting the start position detection signal of the photoreceptor 1 five times, and is used as a stop signal for the optical memory removing means.

On the other hand, the slit detection signal PA is input to the decimal counter 34 and counted. Decimal counter 3
4 includes a decoder, and the decoded output is used as a driving signal for each copying process. Decimal counter 34
is an AND gate 35 with input signals IRA and SPS.
It is reset by a signal from slit signal PA-1, and when it counts six slit signals, it is reset and starts counting from slit signal PA- ₁ .

Signals and signals from the above decimal counter 34
Each copying process is controlled by ISB and IRA. In other words, control is performed to remove the optical memory of the photoreceptor 1. Examples of the drive circuit are shown in FIGS. 5a to 5f. In FIG. 5a, the signal ISB is applied through an inverter 36 to one input terminal of a NAND gate 37, and the output of the NAND gate 37 is applied to the set input terminal of a flip-flop 38. The set output of flip-flop 38 is applied to the base of transistor 39 to switch it. The emitter of the transistor 39 is grounded, and the collector is connected to a power source Vo via a main motor relay 40. Further, the reset input terminal of the flip-flop 38 is supplied with a signal (slit Pa- ₆ ) from the decimal counter 34 via an amplifier 41 and a differentiating circuit 42 and an AND gate 43. The other end of the AND gate 43 has an integral circuit 4.
The output from 4 is provided. This integrating circuit 44
When separating the upper part 15 of the copying machine main body, the power supply +
Since V, etc. are not supplied, the charge accumulated in the capacitor is discharged by the internal resistance (not shown) of the AND gate 43, and one input terminal of the AND gate 43 becomes in the "L" state. When the upper part 15 of the copying machine body is closed, the detection switch 20
When the power switch 21 and the like are closed, power +V is supplied. When power is supplied, a reset signal "L" is supplied to the flip-flop 38, and thereafter becomes "H". The main motor relay 40 includes, for example, the power switch 21,
When the door switch 22 is closed, the detection switch 2
2 changes from the open state to the closed state, the signal ISB
is “L”, so flip-flop 5
The Q output of 2 becomes “H” and the transistor 55
is turned on, so by closing the detection switch 20,
When the power source Vo is supplied, its contacts are closed, power is supplied to a main motor (not shown), the main motor is rotated, and the photoreceptor 1 is rotated.
At this time, the fixing roller 12 and the copy paper conveyance system are also rotated at the same time.

In the present invention, the flip-flop 38 detects the temperature of the heat fixing roller 12, and the temperature is close to the set temperature of 180°C (for example, the temperature that reaches the set temperature in the time it takes for the photoreceptor to rotate several times).
It is configured to be set when the temperature reaches 160℃.
In other words, the other input terminals of the NAND gate 37
A signal from a comparator 45 for detecting a temperature of 160° C. is supplied. + of comparator 45
The voltage of R ₁ · V / R ₂ + R ₁ divided by the resistors R ₂ and R 1 is applied to the terminal on the side, and the voltage on the negative side is applied to the voltage divided by the resistors R ₂ and R ₁ .
A voltage of R _{T h} ·V/R ₃ +R ₄ +R _T h divided by _R 3 and R T h is applied. Here, the resistance R _T h is the resistance of a thermistor that detects the surface temperature of the fixing roller 12, and the resistance value of this thermistor decreases as the temperature increases. For this reason, temperatures above 160℃
If each resistor R ₁ to R ₄ is selected so that R T / _{R 3} +R 4 +R T h<R _{1 /} R ₁ +R ₂ , then if the voltage on the negative side of the comparator ₄₅ is lower than the voltage on the + side (or (equally) output becomes “H”.

On the other hand, the comparator 46 detects the heat fixing roller 12.
This is for setting the temperature to 180℃, and connect R1 and _R1 to the + side terminal.
The voltage at the connection point of R ₂ is supplied to the negative terminal, and the voltage at the connection point of R ₄ and R ₃ is supplied to the negative terminal. Comparator 46 supplies its output via inverter 47 to the base of transistor 48. Therefore transistor 48
If the temperature of the heat fixing roller 12 exceeds 180°C,
The state becomes non-conductive and the supply of power Vo to the heater lamp relay 49 is blocked. In addition, the above set temperature is 180
Each resistance value is determined so that R ₃ +R _T h/R ₃ +R ₄ +R _T h≦R ₁ /R ₁ +R ₂ at temperatures above ℃.

Also, in FIG. 5b, the signal from the decimal counter 34 is supplied to the set input terminal of a flip-flop 52 via an inverter 50 and a differentiating circuit 51. The signal is inputted together with the signal ISB to a NAND gate 53, and the output of this NAND gate 53 is supplied to the reset input terminal of the flip-flop 52 through an AND gate 54 which inputs the signal IRA to one input terminal. The set output of flip-flop 52 is supplied to the base of transistor 55, and
It controls the 5th switch. transistor 5
The emitter 5 is grounded, and the collector is supplied with power V _AC via the high voltage generating circuit 56 of the corona charger 2.

Similarly, the lamp 59 of the lighting device 6 in FIG.
is driven through transistor 58 which is turned on by the set output of flip-flop 57. The set and reset input terminals of the flip-flop 57 are
The signals ISB and IRA are supplied via a circuit similar to that in FIG. 5b, surrounded by dotted lines.

In addition, each of the transfer corona charger 8, the charge eliminating corona charger 10, the optical charge remover 11, the high voltage generating circuits 62, 65, and the charge eliminating lamp 68 in FIGS. By being set, it is driven through the respective husband transistors 61, 64, and 67.

In the circuit configuration as described above, the removal operation of the optical memory according to the present invention will be explained with reference to the time chart of FIG. Therefore, after opening the upper part 15 of the copying machine main body due to a paper jam, etc., the upper part 15 is moved to the lower part 16.
When the switch is closed, the detection switch 20 is closed. At this time, power switch 21 and door switch 2
2 is closed, power supply +V is supplied to the series circuit of resistor R and capacitor C, which resets flip-flop 29 as described above, and its set output Q, that is, signal IRA, becomes "L". . Then, the counter 31 is reset and the signal
ISB becomes “L”. At the same time, the flip-flop 38 is instantaneously brought to "L" by the integrating circuit 44 in the same way as the flip-flop 29 described above, and is in a reset state. At this time, the temperature of the heat fixing roller 12 is
If it is 160°C or higher, the output of the comparator 45 is "H" and the output of the NAND gate 37 is "L".
Then, the flip-flop 38 is set.
However, if the upper part 15 of the copying machine main body is open for a long time, the temperature of the heat fixing roller 12 will drop below 160 DEG C., and the flip-flop 38 will not be set.

Therefore, the heater lamp relay 49 is activated, and the temperature of the heat fixing roller 12 is controlled to the set temperature of 180°C. During this process, the heat fixing roller 12
When the temperature reaches 160℃, the output of NAND gate 37 becomes “L”
The flip-flop 38 is set.
As a result, the transistor 39 becomes conductive and the power source Vo is supplied to the main motor relay 40, causing the main motor to rotate. Due to this rotation, the photoreceptor 1 is rotated, and the heat fixing roller 12 is also rotated at the same time.

As the photoreceptor 1 rotates, a slit signal PA is outputted through the synchronizing disk 23, and this is counted by a decimal counter 34. Therefore, during the period when the slit signal PA- ₆ is output and then the PA- ₀ is output, the MB26 outputs an "H" signal, so the AND gate 27 opens and the inverter 28
A flip-flop 29 is set via the .
At this time, the gate 35 is opened by the output of the inverter 28, that is, the signal SPS, and the set output signal IRA of the flip-flop 29, and the decimal counter 34 is reset. In other words, the starting position of the rotation of the photoreceptor 1 is detected, and thereafter the operation of removing the optical memory of the photoreceptor is performed. This is to search for the start position of the photoreceptor 1 when the photoreceptor 1 is not stopped at the start position due to a paper jam or the like. The signal SPS that detected this start position is
It is counted by the counter 31. counter 31
counts “1”.

After the above, when the starting position of the photoreceptor is detected, the decimal counter 34 is reset and starts counting the next slit signal. Therefore, when the image forming start tip corresponding to the start position of the photoreceptor 1 faces the corona charger 2 in synchronization with the rotation of the photoreceptor 1, the slit signal PA- ₁ of the disk 23 is output. The decimal counter 34 counts and outputs a signal. The flip-flop 52 is set by this signal, and the high voltage generation circuit 5
A power supply V _AC is supplied to the corona charger 6, and the corona charger 2 uniformly charges the photoreceptor 1 from the tip where image formation starts.

Next, when the image forming start end of the photoreceptor 1 reaches the exposure start position, the slit signal PA- ₂ is output, and the flip-flop 57 is set by the signal. Therefore, the exposure lamp 59 is turned on and exposure is performed through the optical system. At this time, the document table 4 is not moved but is stopped at the initial position, and the lower surface 4a of the document table 4 is formed to cause diffuse reflection so that the light from the lamp 59 is irradiated onto the photoreceptor 1. There is.

On the other hand, in the same way as described above, each circuit 62, 65, 68 is driven by the image forming start tip of the photoconductor facing each of the transfer corona charger 8, the charge eliminating corona charger 10, and the optical charge remover 11. be done. The above photoreceptor 1
rotates once, and its starting position (image formation start tip) is
When the starting position is reached, the output of the signal SPS becomes "L", thereby resetting the decimal counter 34. Further, since the output of the NAND gate 32 is "H", the counter 31 receives a signal via the NAND gate 30 in response to the "H" signal from the AND gate 27, and counts this signal. At this time,
The counter 31 is set to “2” along with the start signal from earlier.
This means that it has been counted. Here, in the flip-flop 36 for driving the main motor relay 40, a reset signal is applied to the reset input terminal of the flip-flop 36 via the differentiating circuit 42 based on a signal before the start position of the photoreceptor 1 is detected. However, the signal applied to the set input terminal of flip-flop 38
ISB remains "L" until the signal SPS is output five times and the counter 31 counts "5", and even if the above signal is applied as a reset signal, the flip-flop 38 is not reset and maintains the set state. There is.

After that, the photoconductor 1 rotates, and if it rotates four times from the time when the first signal SPS was output, the counter 31
counts “5”. As a result, the output of the NAND gate 32 is inverted to "L", and the inverter 3
The signal ISB is inverted to "H" through the signal ISB. Therefore, the output of the NAND gate 30 becomes "H", and from now on, the start position signal SPS due to the rotation of the photoconductor is
The counter 31 never counts. This prevents malfunctions by not counting the rotation of the photoreceptor 1 during normal copying operations.

Subsequently, the signal ISB is inverted to "H", and since the photoreceptor continues to rotate, the starting position faces the corona charger 2, and a signal is output. As a result, the output of the NAND gate 53 becomes the signal
Since ISB is "H", it is inverted to "L", the reset terminal of the flip-flop 52 becomes "L", the flip-flop 52 is reset, and the operation of the corona charger 2 is stopped. Thereafter, similarly, the lamp 59 is turned off by a signal, the operation of the transfer corona charger 8 is stopped by a signal, the operation of the charge eliminating corona charger 10 is stopped by a signal, and the lamp 59 is stopped by a signal.
is turned off.

Photoconductor 1 continues to rotate, and the slit signal PA
- When ₆ is output, a corresponding signal is output from the decimal counter 34. This signal is applied to the reset input terminal of flip-flop 38 to amplifier 4.
1 and is added via the differentiating circuit 42,
Flip-flop 38 is reset since the set input terminal is at "H". Therefore, the driving of the main motor relay 40 is stopped, the main motor is stopped, and the starting position of the photoreceptor 1 is made to coincide with the starting position and stopped. When the above-described operation is completed, the optical memory effect caused by opening the upper part 15 of the copying machine main body is removed.

In addition to paper jams, the upper part 15 of the copying machine body is opened for maintenance and the like. in this case,
After opening the power switch 21 or the door switch 22, the upper part 15 and the lower part 16 are separated, and after the maintenance is completed, the upper part 15 and the lower part 16 are closed. Then, when the power switch 21 or the door switch 22 is closed again, driving is performed to eliminate the optical memory effect described above. In other words, the reset terminal R of the flip-flop 29 is set to "L".
The flip-flop 29 is reset when the copying machine is closed and the power is supplied, and the signal is
Since IRA starts from "L", the above-described operation is performed in the same manner.

In the above explanation, the photoreceptor 1 is rotated four times, and during that time, the corona chargers 2, 8, 10 and the lamp 5 are
9 and 68, however, the number of times is not necessarily limited to this, as it changes depending on the conditions of various devices including the photoreceptor 1, the intensity of the external light 19, its irradiation time, the expected safety factor, etc. .

Further, in the above explanation, the corona charger 2 is driven to uniformly charge the photoreceptor 1 to the polarity required for image formation, and then so-called uniform exposure is performed, but the charged charges are discharged by this exposure. . However, in order to charge the photoreceptor 1 to the polarity required for image formation,
Even if the corona charger 2 is not driven, the transfer corona charger 8 may be driven. Therefore, at least the corona charger 8 for transfer and the corona charger 1 for neutralization are provided.
0 and optical static eliminator 11, the object of the present invention can be achieved. In other words, the corona charger 2 and the lamp 59 need not be driven by the signal from the decimal counter 34, and the circuits shown in FIGS. 4b and 4c can be omitted.

Next, an example will be described.

Organic semiconductor photoreceptor 1 as external light 19
After irradiating at 3000 lx for 5 minutes, it was rotated at a circumferential speed of 150 mm/sec. When this photoreceptor 1 was charged with a corona charger 2 with a discharge voltage of 7.2K and a current of 1.2mA, its surface potential increased to 40 to 60% of the charged potential of 500V before irradiation due to the optical memory effect. decreased.

Subsequently, for optical memory removal according to the present invention,
Corona charger for transfer 8, corona charger for charge removal 10
After driving the optical static eliminator 11 and rotating the photoreceptor once, driving the corona charger 2 in the same manner as described above,
Upon charging, the surface potential of the photoreceptor was restored to approximately 85%.

Thereafter, after repeating the above operation four times and charging in the same way, the surface potential of the photoreceptor will recover to about 95%, and even if you copy at this point, the quality will be almost the same as the copy before irradiation. No difference was observed.

As explained above, according to the electrophotographic copying machine of the present invention, in connection with the separation operation of the copying machine where external light is irradiated and optical memory is generated on the photoreceptor, by detecting the closed state of the copying machine rather than the open state, Since the optical memory removal means is driven in conjunction with the power supply to the copying machine main body, there is no need to provide a special means for detecting the optical memory generated on the photoreceptor in the copying machine, and the copying machine main body is used for jam processing, etc. Optical memory can be reliably removed not only when separating for maintenance or other reasons.

In addition, when driving the optical memory removing means, the waiting time of the copying machine, that is, the time when the copying machine becomes available for use, is effectively utilized, and after the optical memory removing means is driven, the copying machine is placed in a ready-to-copy state. This eliminates unnecessary driving of the photoreceptor.

Therefore, when using the copying machine, the main body of the copying machine is always kept in a normal state, and the copying quality after opening and the copying before opening can be maintained at the same quality.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a schematic configuration of an electrophotographic copying machine according to the present invention, FIG. 2 is an external view showing the main body of the copying machine separated into upper and lower parts, and FIG. 3 is a control circuit for removing an optical memory according to the present invention. 4 is a plan view showing an example of a synchronous disk; FIGS. 5 a to 5 are circuit diagrams showing an example of a drive circuit for driving each copying process; FIG. The figure is a time chart for explaining the operations of FIGS. 4 and 5. 1: Photoreceptor, 2: Corona charger, 6: Illumination device, 8: Corona charger for transfer, 9: Copy paper, 1
0: Corona charger for static elimination, 11: Optical static eliminator, 1
2: Heat fixing roller, 15, 16: Upper and lower parts of the copying machine body, 17: Spring, 19: External light, 2
0: Detection switch, 21: Power switch, 22:
Door switch, 40: Main motor relay, 4
7, 53, 56: High voltage generation circuit, 50, 59: Lamp, SPS: Photoconductor start position signal, IRA:
Initial reset signal, ISB: Signal SPS (5
) count signal, R _T h: resistance of thermistor.

Claims (1)

[Scope of Claims] 1. A photoreceptor; an image forming means disposed around the photoreceptor and provided with steps for repeatedly forming images on the photoreceptor; and a means for transferring images formed on the photoreceptor. a means for thermally fixing the image on the copy paper, and a copying machine that accommodates the photoreceptor, the heat fixing device, and the image forming means, and is configured to be separable substantially along the conveyance path of the copy paper. In connection with the separation operation of the copying machine main body, a detection means for detecting the switching of the copying machine main body from an open state to a closed state and outputting a signal responsive thereto when power is supplied; and separation of the copying machine main body. In order to remove the optical memory caused by irradiation of the photoreceptor with external light, the photoreceptor is rotated multiple times and the rotating photoreceptor is charged, and in order to remove this charged charge, the image formation is performed. an optical memory removing means for operating a part of the process of the means; a temperature detecting means for detecting the temperature of the heat fixing means; and a temperature detecting means for detecting a temperature close to a set temperature of the fixing temperature of the heat fixing means. an output means for outputting a signal by the copying machine body; and in response to power supply after the copying machine main body is in a closed state, the optical memory is removed based on the detection signal output by the upper and lower separation by the detection means and the signal from the output means. An electrophotographic copying machine comprising: a control means for energizing the means; and a control means for energizing the means.