JP2753380B2 - Electrophotographic equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrophotographic apparatus such as a laser printer and a copying machine.

[Related Art] For example, a laser printer has a laser scanner unit for scanning a laser beam by controlling the rotation of a polygon mirror by a polygon motor. After charging the photoconductor of the photoconductor drum by the charging unit, the laser beam is radiated from the laser scanner unit to the photoconductor to record information as an electrostatic latent image. And visualized. on the other hand,
Transfer paper is sent from a paper feed unit provided with a paper feed cassette, and the transfer paper is transported to a transfer unit for transferring a toner image from the photosensitive drum, and toner is transferred from the photosensitive drum at a timing when the transfer paper reaches the transfer unit. The image is transferred to the transfer paper. Then, the transfer paper after the transfer is completed is discharged after being fixed by a fixing device.

In such a laser printer, a feed sensor is provided in the middle of the transport path, and the time until the transfer paper sent from the paper feeding unit is detected by the sensor is managed by a microprocessor constituting the control unit main body, The time from when the sensor detects the transfer paper to when it stops detecting the transfer paper is also managed by the microprocessor, and, for example, jam detection is performed.

[Problems to be Solved by the Invention] However, if the transfer state management of the transfer paper relies on the time management by the microprocessor as described above, there is a problem that the load on the microprocessor is correspondingly increased.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electrophotographic apparatus capable of reducing the load on the microprocessor in managing the transfer state of the transfer paper, and thus using a low-performance microprocessor.

Means for Solving the Problems The present invention has a laser scanner unit for scanning a laser beam by controlling the rotation of a polygon mirror by a polygon motor, and irradiating a charged photosensitive member with the laser beam from the laser scanner unit. In an electrophotographic apparatus that forms an electrostatic latent image, develops the electrostatic latent image and visualizes the electrostatic latent image, and transfers the latent image to a transfer paper that has been transported along a transport path, the transport paper in the transport path is transport-controlled. A feed motor,
The clear state is released by the feed sensor that detects the transfer paper passing the predetermined position of the transport path and the ON signal of the feed motor, and the ON signal of the polygon motor and the ON / OFF signal of the feed sensor are counted and various mode values are output. And a microprocessor for managing the transfer state of the transfer paper based on the various mode values output by the mode value output means.

[Operation] In the present invention having such a configuration, when the feed motor is in the off state, the mode value of the mode value output means is cleared and the mode value “0” is output. When the feed motor is turned on, the clear state of the mode value output means is released by the ON signal at that time. Even in this state, the mode value of the mode value output means does not change. Thereafter, the output of the mode value output means changes by counting the ON signal of the polygon motor and the ON / OFF signal of the feed sensor. The microprocessor can read the mode value output from the mode value output means to know the transfer state of the transfer sheet.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In this embodiment, an embodiment in which the present invention is applied to a laser printer will be described.

FIG. 1 is a structural view of a laser printer. As shown in the drawing, a photosensitive drum 2 having a surface made of a photosensitive material of a photoconductive substance is arranged at a substantially central portion in a housing 1. The photosensitive drum 2 is driven by a feed motor 3 to rotate in one direction, that is, clockwise in the figure. The photosensitive drum 2 is charged around the photosensitive drum 2 according to an electrophotographic process. Charging unit 4 to be charged, this charging unit 4
A laser scanner unit 5 for irradiating a laser beam to the charged photoconductor to expose and record information to form an electrostatic latent image, and to apply toner as a developer to the electrostatic latent image formed on the photoconductor. A developing unit 6 to be adhered; a transfer unit 7 for transferring a toner image from the photosensitive drum 2 to a fed transfer paper; a cleaning device 8 for removing residual toner from the transferred photosensitive drum 2; a transferred photosensitive drum 2 Are disposed in order.

A paper supply unit 10 is provided on one side of the housing 1, and a paper supply roller 12 and a paper supply roller 12 that can freely contact and separate from the upper surface of the transfer paper 11 stored therein are provided in the paper supply unit 10. Transfer paper sending means comprising a sheet feeding solenoid 13 for causing the sheet to contact and separate.

When the rotating paper feed roller 12 comes into contact with the transfer paper 11 for a predetermined time by the paper feed solenoid 13, the transfer paper 11
Are fed one by one from the paper feed unit 10 at a predetermined timing, and the fed transfer paper 11 is transported to the position of the transfer unit 7 via a transport path 14 provided with transport rollers (not shown). It has become. A feed sensor 15 is provided in the middle of the transport path 14.

The transfer paper 11 on which the toner image has been transferred from the photosensitive drum 2 in the transfer unit 7 is supplied to a heat fixing unit 16, where the transfer paper 11 is thermally fixed by the heat fixing unit 16, and then discharged by the discharge roller 17.
The paper is discharged out of the housing from a transfer paper discharge port 18 provided on the other side.

FIG. 2 is a detailed view of the laser scanner unit 5. As shown in the figure, a laser oscillator 21 for emitting a laser beam, a laser control circuit 22 for driving the laser oscillator 21, a start sensor 23 for detecting a start position of the laser beam, and a polygon mirror are rotationally controlled in the unit 5. A polygon motor 24, a polygon motor drive circuit 25 for controlling the drive of the motor 24, and a PLL control circuit 26 for controlling the number of rotations of the motor 24 by the drive circuit 25 are provided.

FIG. 3 is a block diagram showing a circuit configuration of the laser printer. In the figure, reference numeral 31 denotes a microprocessor constituting the control unit main body, 32 denotes an input / output port, and these are connected by a bus line 33.

The input / output port 32 includes a feed solenoid drive circuit 34 for driving the feed solenoid 13, a motor drive circuit 35 for driving the feed motor 3, the laser scanner unit 5, the charging unit 4, and the transfer unit 7. A high-voltage power supply 36 that supplies a high voltage, a fixing heater 37 of the heat fixing unit 16, an operation unit 38 provided with a start key and a key for setting the number of prints, a mode counter circuit 39, and various sensors 40 including the feed sensor 15 are provided. Sensor circuits 41 to be controlled are respectively connected.

FIG. 4 shows a main part configuration, wherein the mode counter circuit 39 comprises a mode counter 42, a one-shot timer 43,
An input OR gate 44, a rising / falling detection circuit 45, and a rising detection circuit 46.The sensor circuit 41 outputs a signal FSO indicating whether or not the feed sensor 15 is detecting that the transfer paper 11 is passing therethrough.・ Fall detection circuit 45
To supply. This signal FSO corresponds to the feed sensor 15
Is at a high level when the transfer paper 11 is not detected, and is inverted to a low level when the feed sensor 15 detects the transfer paper 11.

The I / O port 32 is an on / off signal P for the polygon motor.
SYN is supplied to the laser control circuit 22 and to the rising detection circuit 46. Meanwhile, the laser control circuit
Reference numeral 22 supplies the I / O port 32 with a signal STS indicating whether or not the start sensor 23 has detected the start of laser beam scanning. The signal STS is at a high level when the start sensor 23 does not detect the start of scanning, and is inverted to a low level when the start sensor 15 detects the start of scanning.

The I / O port 32 supplies a feed motor on / off signal ST1 / STOP to the motor drive circuit 35 and to a clear terminal CL of the mode counter 42.

The mode counter circuit 39 detects the rise and fall of the signal FSO from the sensor circuit 41 with the rise / fall detection circuit 45, and detects the rise of the polygon motor on / off signal PSYN with the rise detection circuit 46. Then, the detection signal is supplied to the one-shot timer 43 via the OR gate 44. This one-shot timer circuit 43
Converts the detection signal into a pulse signal MCK1 having a sufficient width and supplies it to the mode counter 42. The mode counter 42 counts the number of inputs of the pulse signal MCK1, and supplies the count value as a mode value MD to the I / O port 32.

In the present embodiment having such a configuration, the state before starting the printing is such that the feed motor on / off signal ST1 / STOP from the I / O port 32 is at the low level by the off signal, so that the mode counter 42 Has been cleared. Therefore, the count value of the mode counter 42 is “0”, that is, the mode value MD supplied to the I / O port 32 is “0”.

When the start key is operated to start printing in this state, the microprocessor 31 sets the feed motor on / off signal ST1 / STOP to a high level on signal via the I / O port 32. As a result, the clear state of the mode counter 42 is released, and the motor drive circuit 35 drives the feed motor 3 to rotate. Thus, the photosensitive drum 2, the transport roller, the paper feed roller 12, and the like rotate.

Subsequently, the microprocessor 31 is turned on for the polygon motor via the I / O port 32. The off signal PSYN is turned on, that is, set to a high level. Thus, the laser control circuit 22 activates the polygon motor 24 via the polygon motor drive circuit 25. Thus, the polygon mirror is driven to rotate, and scanning of the laser beam from the laser oscillator 21 is started. The rise of the polygon motor on / off signal PSYN is detected by the rise detection circuit 46. Then, a detection signal is supplied from the rise detection circuit 46 to the one-shot timer 43 via the OR gate 44, and the one-shot timer 43
Is converted into a pulse signal MCK1 and supplied to the mode counter. As a result, the mode counter 42 counts up by one and outputs the mode value “1”.

At this time, the microprocessor 31 also turns on the feed solenoid ON / OFF signal to the feed solenoid drive circuit 34 via the I / O port 32. As a result, the paper supply solenoid 13 is operated, the paper supply roller 12 is sucked for a certain time, and comes into contact with the upper surface of the transfer paper 11. In this way, the transfer paper 11 is sent out from the paper supply unit 10 to the one-sheet transport path 14.

However, if the polygon motor 24 or polygon mirror does not rotate normally due to some abnormality, the start sensor
The scanning start of the laser beam is not detected by 23, and the signal STS from the laser control circuit 22 remains at the high level. Therefore, if the signal STS does not become low level within a certain time after turning on the polygon motor on / off signal PSYN, the microprocessor 31 determines that the rotation of the polygon mirror is stopped or abnormal and generates an error.

On the other hand, the transfer paper 11 passing through the conveyance path 14 is
When the signal is detected by the signal 15, the signal FSO from the sensor circuit 41 falls from the high level to the low level. The falling of the signal FSO is detected by the rising / falling detection circuit 45. Then, the detection signal from the rise / fall detection circuit 45 is OR gated.
The pulse signal MCK1 is supplied to the one-shot timer 43 via 44, and is converted into a pulse signal MCK1 having a width sufficient for the operation of the counter 42 by the one-shot timer 43 and supplied to the mode counter 42. As a result, the mode counter 42 counts up by one and outputs the mode value “2”.

Further, when the transfer paper 11 passes through the feed sensor 15, the signal FSO from the sensor circuit 41 rises from a low level to a high level. The rising of the signal FSO is detected by a rising / falling detection circuit 45. The detection signal from the rise / fall detection circuit 45 is supplied to the one-shot timer via the OR gate 44.
43, and the one-shot timer 43
Is converted into a pulse signal MCK1 having a width sufficient for the operation described above and supplied to the mode counter 42. As a result, the mode counter 42
Counts up by one and outputs the mode value “3”.

Thereafter, the transfer paper 11 is transferred by the transfer unit 7 and thermally fixed by the heat fixing unit 16, and then is discharged from the transfer paper discharge port 18 to the outside of the housing by the discharge roller 17.

The feed motor on / off signal ST1 / STOP and polygon motor on / off signal PS from the I / O port 32
YN becomes an off signal and becomes low level. As a result, the operation of the feed motor 3 is stopped, and the mode counter 42 is cleared, and the mode value becomes “0”.

FIG. 5 shows the above operation in a timing chart.

Therefore, by reading the mode value MD from the mode counter 42 via the I / O port 32, the microprocessor 31 can easily know what transport state the transfer paper 11 is currently in.

That is, as shown in FIG. 6, if the mode value MD is "0", the microprocessor 31 continues to feed paper.
That is, it is determined whether the feed motor on / off signal ST1 / STOP is an on signal or an off signal. If the signal is an off signal, the operating state (A), that is, a state in which transfer paper is not transported at all, is determined. On / off signal ST for feed motor
If 1 / STOP is an ON signal, the operation state (B), that is, the state in which the sheet supply roller 12 and the conveyance roller are activated, is determined. Also, after a predetermined time has elapsed since the feed motor on / off signal ST1 / STOP was turned on, it is determined that the polygon motor on / off signal PSYN is turned on to start the polygon motor 24 in the laser scanner unit 5.

If the mode value MD is "1", it is determined whether or not the polygon mirror is rotating normally based on the state of the signal STS from the laser control circuit 22. If the rotation is not normal, an error is generated. On the other hand, when the rotation is normal, the operation state (C), that is, the paper feeding solenoid
13 is turned on, and the state in which the transfer paper 11 is sent from the paper supply unit 10 to the transport path 14 is determined.

If the mode value MD is "2", the operation state (D), that is, the state that the feed sensor 15 is detecting passage of the transfer paper 11 is determined.

Further, if the mode value MD is "3", the operation state (E),
That is, it is determined that the feed motor 3 and the polygon motor 24 are stopped after a predetermined time has passed after the transfer paper 11 has passed the feed sensor 15.

In this way, the microprocessor 31 can manage what transport state the transfer paper 11 is in by simply reading the mode value MD of the mode counter 42 via the I / O port 32. It is not necessary to provide a timer to manage the time from when the paper is fed to when the feed sensor detects the transfer paper or to manage the time when the transfer paper passes through the feed sensor. Therefore, the load on the microprocessor 31 can be reduced.

Accordingly, even if the transfer speed of the transfer paper is increased for high-speed printing, the microprocessor 31 can sufficiently cope with the problem, and sufficient control can be achieved even if the microprocessor is switched from the 8-bit type to the 4-bit type.

In the above embodiment, the mode signal is used to count the ON signal of the polygon motor and the ON / OFF signal of the feed sensor and output various mode values.
Various mode values may be output based on a predetermined logic based on a polygon motor ON signal and a feed sensor ON / OFF signal using a mode decoder. In the above embodiment, the present invention is applied to a laser printer. However, the present invention is not limited to this, and it is needless to say that the present invention can be applied to a copying machine using an electrophotographic process.

[Effects of the Invention] As described in detail above, according to the present invention, the load on the microprocessor in managing the transfer state of the transfer paper can be reduced,
Therefore, it is possible to provide an electrophotographic apparatus capable of using a low-performance microprocessor.

[Brief description of the drawings]

1 shows an embodiment in which the present invention is applied to a laser printer. FIG. 1 is an overall structural view, FIG. 2 is a detailed view of a laser scanner unit, FIG. 3 is a block diagram of a circuit configuration, and FIG. FIG. 5 is a flowchart showing the operation timing of each part in FIG. 4, and FIG. 6 is a flowchart showing the state determination processing when transferring the transfer paper by the microprocessor. 3: Feed motor, 5: Laser scanner unit, 15
... Feed sensor, 21 ... Laser oscillator, 22 ... Laser control circuit, 23 ... Start sensor, 24 ... Polygon motor, 31 ...
Microprocessor, 42: Mode counter, 45: Rise / fall detection circuit, 46: Rise detection circuit.

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FI G03G 15/00 518 G03G 15/00 526 526 15/04 15/04 H04N 1/00 108Q 21/14 G03G 21/00 372 H04N 1 / 00 108 B41J 3/00 D (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 21/00 370-540 G03G 15/00 510-534 G03G 15/04 B41J 11/42

Claims (1)

(57) [Claims] A laser scanner unit for scanning a laser beam by controlling the rotation of a polygon mirror by a polygon motor, and irradiating a charged photosensitive member with the laser beam from the laser scanner unit to form an electrostatic latent image. An electrophotographic apparatus that develops the electrostatic latent image and visualizes the electrostatic latent image, and then transfers the electrostatic latent image to transfer paper that has been transported along the transport path, comprising: a feed motor that controls transport of the transfer paper in the transport path;
A clear state is released by a feed sensor that detects a transfer sheet passing through a predetermined position of the transport path and an ON signal of the feed motor, and counts ON signals of the polygon motor and ON / OFF signals of the feed sensor to perform various operations. An electrophotographic apparatus comprising: a mode value output unit that outputs a mode value; and a microprocessor that manages a transfer state of the transfer sheet based on various mode values output by the mode value output unit.