JPH04320282A - Form carrying device for laser printer - Google Patents

Abstract

PURPOSE:To execute first printing as soon as possible at the time of starting printing and further, to prevent a carrying motor from being continuously driven more than required at the time of stopping the printing. CONSTITUTION:The form carry device is provided with a synchronizaion detecting means 15 detecting whether a polygon motor is rotated at constant speed or not, a paper feeding solenoid 23 controlling the carrying of a form, a feeding motor 13, and a microprocesser 31 starting the carrying of the form 21 by the paper feeding solenoid 23 after the synchronization detecting means 15 detects that the polygon motor is rotated at the constant speed, at the time of starting the printing, and stopping the carrying of the form by the feeding motor 14 after the synchronization detecting means 15 detects that the polygon motor is not rotated at the constant speed, at the time of stopping the printing.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper conveying device for a laser printer.

0002

[Prior Art] Laser beam output from a laser generator
The laser scanner unit has a laser scanner unit that scans a photoreceptor by reflecting the image on a polygon mirror rotated by a polygon motor. Laser printers are widely used in which printing is performed by irradiating a laser beam to form an electrostatic latent image, developing this electrostatic latent image to make it visible, and then transferring it to paper that is being transported. Are known. Incidentally, the laser beam irradiation from the laser scanner unit was controlled on and off in response to the on and off of the irradiation permission signal input to the unit.

[0003] Time-series operations when printing with a conventional laser printer will be explained. To start printing, first drive the polygon motor, and after a set time (for example, 6 seconds) after driving, turn on the irradiation permission signal to start irradiation with the laser beam, and at the same time turn on the transport motor. The printer was driven and printing started. On the other hand, when printing is to be stopped, the drive of the polygon motor is stopped and the irradiation permission signal is turned off, and then, after a set time, the drive of the transport motor is stopped and printing is stopped.

0004

[Problem to be Solved by the Invention] The set time from when the polygon motor is driven at the start of printing to when the transport motor starts to be driven is such that the polygon motor rotates at a constant speed considering the worst conditions. is set to a sufficient amount of time required for Therefore, even if the polygon motor is rotating at a constant speed before the set time has elapsed, it is necessary to wait until the set time has elapsed before starting driving the transport motor. For this reason, there was a problem that printing on the first sheet (first printing) could not be performed quickly.

Furthermore, when printing is stopped, the polygon motor is stopped and then the transport motor is stopped after a set time has elapsed, so the transport motor may be driven more than necessary. There was a problem with continuing.

The present invention has been made in view of the above points, and its purpose is to be able to perform the first print as quickly as possible when printing starts, and to continue driving the transport motor more than necessary when printing is stopped. An object of the present invention is to provide a paper conveyance device for a laser printer that can prevent such problems.

[0007]

[Means for Solving the Problems] The present invention provides a laser beam that scans a photoconductor by reflecting a laser beam output from a laser generator by a polygon mirror rotated by a polygon motor. It has a scanner unit and irradiates the charged photoconductor with a laser beam from the laser scanner unit to form an electrostatic latent image, and after this electrostatic latent image is developed and visualized. In a laser printer that performs printing by transferring onto paper that is being conveyed, a synchronization detection means that detects whether the polygon motor is rotating at a constant speed, a conveying means that conveys the paper, and a means that starts printing. If printing is to be stopped, the synchronization detection means detects that the polygon motor is rotating at a constant speed, and then the transport means is driven. A sheet conveyance device for a laser printer, characterized in that it comprises a control means for stopping the driving of the conveyance means after it is detected that the paper conveyance device stops rotating.

[0008]

[Operation] At the start of printing, the synchronization detection means detects whether the polygon motor is rotating at a constant speed, and after this synchronization detection means detects that the polygon motor is rotating at a constant speed, paper conveyance is started. When the printing is stopped, the synchronization detection means detects that the polygon motor is no longer rotating at a constant speed, and then the conveyance of the paper is stopped.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A paper conveying device for a laser printer according to an embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a photosensitive drum 12 whose surface is made of a photoconductive material is disposed approximately at the center of the housing 11. As shown in FIG. The photoreceptor drum 12 is rotated in one direction, that is, clockwise in the figure, by a feed motor 13 composed of, for example, a stepping motor. Charging unit 1 that charges the photoreceptor of the drum 12
4. A laser scanner unit 15 that irradiates the photoconductor charged by the charging unit 14 with a laser beam to record information by exposure to form a electrostatic latent image, and a developer is applied to the electrostatic latent image formed on the photoconductor. a developing section 16 to which toner is attached;
A transfer unit 17 that transfers the toner image from the photoconductor drum 12 to the paper being fed, a cleaning device 18 that removes residual toner from the photoconductor drum 12 that has already been transferred, and a static eliminator 19 that eliminates the static electricity from the photoconductor drum 12 that has already been transferred. They are arranged in order.

A paper feed section 20 is provided on one side of the housing 11, and the paper 2 stored inside the paper feed section 20 is provided with a paper feed section 20.
A paper feed roller 22 that can move toward and away from the paper feed roller 22 and a paper feed solenoid 23 that moves the paper feed roller 22 toward and away from each other are provided on the upper surface of the paper feed roller 1 .

The paper feed roller 22 rotated by the paper feed solenoid 23 contacts the paper 21 for a predetermined time, so that the paper 21 is removed from the paper feed section 20 at a predetermined timing.
The paper 21 is fed in sheet by sheet, and the fed paper 21 is conveyed to the transfer section 17 via a conveyance path 24 provided with conveyance rollers (not shown). A feed sensor 25 is provided in the middle of the conveyance path 24.

In the transfer section 17, the photosensitive drum 12
The paper 21 on which the toner image has been transferred is supplied to a heat fixing section 26, and after being heat-fixed in the heat fixing section 26, the paper 21 is discharged from a paper discharge port 28 provided on the other side of the housing 11 by a discharge roller 27. It is designed to be discharged outside the casing.

FIG. 2 is a block diagram showing the circuit configuration.
Reference numeral 1 denotes a microprocessor constituting the main body of the control unit, 32 an input/output port, and these are connected by a bus line 33. Note that a control program for performing the processing shown in FIG. 4 is stored in the memory of this microprocessor 31.

The input/output port 32 includes a paper feed solenoid drive circuit 34 that drives the paper feed solenoid 23, a motor drive circuit 35 that drives the feed motor 13,
A high voltage power source 36 that supplies high voltage to the charging section 14 and the transfer section 17, a fixing heater 37 of the thermal fixing section 26, an operation section 38 provided with a start key, a key for setting the number of prints, etc., and the feed sensor 25. A sensor circuit 42 for controlling various sensors 41 included therein and the laser scanner unit 15 are connected to each other.

Further, the laser scanner unit 15 is shown in FIG.
As shown in FIG. 2, a laser diode 51 that emits a laser beam, a laser control unit 52 that drives the laser diode 21, and a light receiver that detects the starting position of the laser beam. Start sensor 5 consisting of an element such as a PIN diode
3. A polygon motor drive circuit 55 that drives and controls a polygon motor (not shown) that rotates the polygon mirror 54.
It is composed of etc.

The laser control section 52 is composed of a microprocessor and its peripheral circuits.
Its enable terminal EN is connected to the I/O port 32. Then, a laser diode ON enable signal (irradiation permission signal) is input to the enable terminal EN.
When turned on, the laser control section 52 starts controlling the laser diode 51 to emit a laser beam. On the other hand, when the laser diode ON enable signal (irradiation permission signal) input to the enable terminal EN is turned off, the laser control section 52 controls the laser diode 51 to
The control for irradiating the beam is stopped. The laser beam emitted from the laser diode 51 is reflected by one surface of the rotating polygon mirror 54, and after being reflected by the mirror 57, the photosensitive drum 12 is scanned. The physical position of the start sensor 53 is set so that it receives the reflected beam when the laser beam enters a specific area of the mirror 57. The polygon mirror 54 is rotated at a constant speed by a polygon motor (not shown).
When the start sensor 53 rotates at a constant speed, a reflected beam is incident on the start sensor 53 at regular intervals. The laser control section 52 detects the reflected beam incident on the start sensor 53, measures the time interval at which the reflected beam is incident, and controls the polygon mirror 54 (or polygon motor). A synchronization determination means is provided for determining whether the rotation is at a constant speed.

Furthermore, the polygon motor drive circuit 55
is connected to the I/O port 32, and controls driving and non-driving of a polygon motor (not shown) in response to control signals output from the microprocessor 31.

Next, the operation of one embodiment of the present invention constructed as described above will be explained with reference to the flowchart of FIG. First, when the temperature of the heat fixing section 26 reaches the printable area after the power is turned on, the printer enters a stage 0 standby state. In this state of stage 0, when the microprocessor 31 receives a print start command, the process shown in FIG. 4 is started under the control of the microprocessor 31. first,
As shown in step S1, a control signal is output from the microprocessor 31 to the polygon motor drive circuit 55 via the I/O interface 32, and the polygon motor drive circuit 55 is driven. As a result, a polygon motor (not shown) is driven and the polygon mirror 54 starts rotating. Furthermore, a control signal is output to the feed motor drive circuit 35 via the I/O interface 32, and the feed
Rotation of the motor 13 is started (stage 1). Note that a timer (not shown) in the microprocessor 31 starts counting the time from when the polygon motor (not shown) starts rotating. From this stage 1, the microprocessor 31 monitors whether a polygon motor (not shown) is rotating at a constant speed. That is, it is monitored whether or not the synchronization detection means determines that the polygon motor (not shown) is rotating at a constant speed. In step S2, it is determined that the polygon motors are synchronized, that is, the synchronization detection means determines that the polygon motors (not shown) are rotating at a constant speed. While the determination in step S2 is "NO", the process proceeds to step S3, where it is determined whether the time counted by the timer is less than or equal to B seconds. As long as the time counted by the timer is equal to or less than B seconds, the monitoring in step S2 is repeated.

After the polygon motor (not shown) starts rotating, the polygon motor reaches constant speed rotation, and the synchronization detection means determines that the polygon motor is rotating at a constant speed. And, in step S2 above, "Y
ES'', the microprocessor 31 turns on and outputs a laser diode ON enable signal to the EN terminal of the laser control circuit 52 (step S4). As a result, the laser diode 51 is driven by the laser control section 52, and a laser beam is emitted from the laser diode 51. This laser beam is reflected on one surface of the polygon mirror 54 rotating at a constant speed, and is reflected onto the photoreceptor drum 1.
2 (stage 2).

[0021] Then, after a certain period of time has passed since the determination in step S2 is ``YES'', the microprocessor 31
is the paper feed solenoid drive circuit 3 via the I/O port 32.
4 to operate the paper feed solenoid 23 for a certain period of time (step S5, stage 4). As a result, the paper feed roller 22 is attracted for a certain period of time and comes into contact with the upper surface of the paper 21, and one paper is sent from the paper feed section 20 to the transport path 24 (step S6). Thereafter, toner is attached to the electrostatic latent image formed on the photoreceptor of the photoreceptor drum 12 in the developing section 16, and this toner image is transferred onto the paper 21 in the transfer section 17. Then, the paper 21 is supplied to a heat fixing section 26, and after being thermally fixed in the heat fixing section 26, the paper 21 is ejected from the casing through a paper ejection port 28 provided on the other side of the casing 11 by an ejection roller 27. (Step S7).

[0022] In the above-mentioned operation, when there is a plurality of pages to be printed, the processes of steps S5 to S6 are repeated. and,
When printing of the final page is completed, the microprocessor 31 connects the polygon motor drive circuit 55 via the I/O port 32.
A control signal is output to the polygon motor (not shown) to stop driving the polygon motor (not shown) (step S8, stage 5).

Thereafter, the microprocessor 31 monitors whether the synchronization of the polygon motor is off, that is, whether the polygon motor (not shown) no longer rotates at a constant speed using the synchronization detection means (step S9, stage 6). and,
If the determination in step S9 is YES, the microprocessor 31 turns off and outputs the laser diode ON enable signal to the EN terminal of the laser control circuit 52 via the I/O interface 32. (Step S
10, stage 7). Furthermore, the microprocessor 31
outputs a control signal to the feed motor drive circuit 35 via the I/O port 32 after a certain period of time after turning off and outputting the laser diode ON enable signal.
Control is performed to stop the rotation of the motor 13 (step S11, stage 11). Thereafter, the process returns to the standby state of stage 0.

[0024] Note that in step S1, the polygon model
If the polygon motor is still not rotating at a constant speed even after B seconds or more have elapsed since the motor (not shown) started driving, the determination in step S3 is "YES", and the determination in step S11 is Then, the polygon motor (not shown) is stopped. This is performed when the polygon motor or the motor drive circuit 55 is abnormal.

As described above, laser beam irradiation is started after the synchronous detection means detects that the polygon motor (not shown) rotates at a constant speed. The laser beam is never irradiated before constant speed rotation. For this reason, before the polygon motor rotates at a constant speed, the toner adheres to the electrostatic latent image formed on the photoreceptor of the photoreceptor drum 12 by the laser beam irradiation, and the excess toner image is removed. It is possible to prevent unnecessary consumption of toner.

Furthermore, since the conveyance of the paper 21 is started when it is detected that the polygon motor rotates at a constant speed,
First printing can be performed earlier than when conveyance of the paper 21 is started by time management as in the conventional case.

[0027] Also, when printing is stopped, the polygon mode is actually
After the motor leaves the constant speed rotation state, turn off the laser diode enable ON enable signal, and then turn off the laser diode enable signal.
Since the scanning of the polygon motor is stopped, the timing at which the polygon motor leaves the constant speed rotation state and the signal from the start sensor 53 is turned off can be synchronized, thereby simplifying the hardware design.

Furthermore, when printing is to be stopped, the synchronization detection means detects that the polygon motor is no longer rotating at a constant speed, and then the paper feed solenoid 23 stops conveying the paper. It is possible to prevent the transport motor from continuing to be driven more than necessary when the transport motor is stopped.

[0029]

Effects of the Invention As described in detail above, according to the present invention, first printing can be performed as quickly as possible when printing is started, and moreover, when printing is stopped, the transport mode can be used more than necessary.
Therefore, it is possible to provide a paper conveyance device for a laser printer that can prevent the printer from continuing to be driven.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a laser printer according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the overall configuration of the laser printer.

FIG. 3 is a block diagram showing the configuration of a laser scanner unit.

FIG. 4 is a flowchart showing a printing operation.

FIG. 5 is a timing chart showing the timing of printing operations.

[Explanation of symbols]

13...Feed motor, 15...Laser scanner unit, 23...Paper feed solenoid, 31...Microprocessor,
35...Motor drive circuit, 51...Laser diode, 53
...Start sensor, 54...Polygon mirror.

Claims (1)

[Claims] Claim 1: A polygon mirror rotated by a polygon motor that emits a laser beam output from a laser generator.
The laser scanner unit is equipped with a laser scanner unit that scans the photoreceptor by reflecting it onto the photoreceptor, and forms an electrostatic latent image by irradiating the charged photoreceptor with a laser beam from the laser scanner unit. In a laser printer that develops an electrostatic latent image to make it visible and then transfers it to a sheet of paper to be printed, synchronization detection means detects whether the polygon motor is rotating at a constant speed; The conveying means for conveying the paper and the synchronization detecting means to detect the polygon mode when printing is to be started.
When it is detected that the polygon motor is rotating at a constant speed, the conveyance means is driven and printing is stopped, the synchronization detection means detects that the polygon motor is no longer rotating at a constant speed, and then the 1. A paper conveyance device for a laser printer, comprising a control means for stopping driving of the conveyance means.