JP2003341133A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a starting time before a steady rotation from changing because of an oil viscosity change due to an environmental temperature change in particularly a scanner motor comprising an oil-driven bearing. <P>SOLUTION: An imaging apparatus is provided, which has a rotary polyhedron including a bearing with a thermal behavior, a means for rotating the rotary polyhedron by a predetermined period, and a means for measuring an environmental temperature around the apparatus. The apparatus is configured to include a control means for forcibly rotating the rotary polyhedron regardless of an imaging start instruction in the case where the apparatus is left under a predetermined environment for not shorter than a predetermined time without driving to image. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus such as a copying machine, a printer or a FAX, which is composed of a laser scanner unit equipped with a polygon motor, and more particularly,
The present invention relates to control of a polygon motor that drives a polygon mirror to rotate.

[0002]

2. Description of the Related Art A polygon motor used in an electrophotographic apparatus that exposes an image with a laser beam is controlled to rotate at a high speed and to have a high rotational accuracy. Normally, the polygon motor is stopped when the image forming operation is not performed, and starts rotating based on the image forming start instruction. Image exposure is performed after reaching the desired rotation cycle required for image formation, and the image formation is stopped after the image formation is completed. Conventionally, the bearings of polygon motors often use ball bearings and oil, which are more cost-effective than air bearing types, and both ball bearings and oils are used as lubricating oil. Is used.

[0003]

In recent years, oil systems, which are more advantageous in terms of cost and noise, have become the mainstream. However, this type is affected by the temperature characteristics of the oil, and the viscosity of the oil increases especially in a low temperature environment, so the time from the start of the polygon motor to the steady rotation at the desired cycle becomes very long. . That is, it takes a long time until the image can be formed. Further, in recent years, a compact image forming apparatus has been desired, but in the conventional large-sized apparatus, it is the paper feeding time rather than the exposure that affects the first copy time. Exposure time is an important factor. Therefore, when providing a low-cost, low-noise, and small-sized image forming apparatus, the first copy time becomes long depending on the environmental temperature, especially in the polygon motor using oil in the bearing portion. .

Therefore, in the present invention, the delay of the first copy time can be suppressed especially in a low temperature environment by starting the polygon motor to a steady rotation in a stable time without being affected by the environmental temperature. An object is to provide a possible forming device.

[0005]

In order to achieve such an object, the present invention comprises, in the invention described in claim 1, a plurality of reflecting surfaces for reflecting laser light, and has a temperature characteristic of A BD that receives a rotating polyhedron provided with a certain bearing and the reflected light from the rotating polyhedron, and outputs a reference signal that serves as a reference for the writing start position of the main scanning line on the image carrier.
In an image forming apparatus including a sensor and a drive control unit for rotationally driving the rotating polyhedron at a predetermined cycle based on the reference signal, the environment (temperature, humidity) around the image forming apparatus is measured. Environment measuring means, and an inter-job drive control means for forcibly rotating and driving the rotating polyhedron regardless of an image formation start instruction when the apparatus is left in a predetermined environment for a predetermined time or more without performing an image forming operation. It is characterized by having.

Further, a pseudo reference signal generating means for generating a pseudo reference signal having a cycle equivalent to that of the reference signal without using a BD sensor is provided, and when the rotating polyhedron is rotationally driven by the inter-job drive control means. By controlling the rotation cycle based on the pseudo reference signal, the rotating polyhedron is steadily rotated at a desired cycle without emitting laser light.

Alternatively, if the temperature measuring means for measuring the temperature of the rotating polyhedron and the temperature detected by the temperature measuring means are lower than a predetermined temperature T1, the rotating polyhedron is irrelevant regardless of the image formation start instruction. In the method, the rotating polyhedron is started up to a desired rotation speed in a stable time also in a method characterized by having a rotating body temperature control means for forcibly rotating the rotating polyhedral body and continuing the rotating drive until a predetermined temperature T2 is reached. To enable that. Further, similarly to the inter-job drive control means, the rotation cycle can be controlled based on the pseudo reference signal.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of the image forming apparatus of this embodiment. The image forming apparatus of the present embodiment is an electrophotographic system, and will be described as a relatively small-sized, low-cost, high-speed color image output apparatus in which a plurality of image forming units are arranged in parallel.

The image output section 1P is roughly classified into the image forming section 1
0 (four stations a, b, c, and d are arranged in parallel and have the same configuration), a sheet feeding unit 20, an intermediate transfer unit 30, a fixing unit 40, and a control unit (not shown). To be done.

Further, each unit will be described in detail. The image forming unit 10 has the following configuration. Photosensitive drums 11a and 11b as image carriers,
11c and 11d are pivotally supported at their centers, and are rotationally driven in the direction of the arrow. The primary chargers 12a, 12b, 12 face the outer peripheral surfaces of the photosensitive drums 11a to 11d in the rotation direction thereof.
c, 12d, laser scanner units 13a, 13b,
13c, 13d, developing devices 14a, 14b, 14c, 1
4d is arranged. The primary chargers 12a to 12d apply a uniform amount of charge to the surfaces of the photosensitive drums 11a to 11d. Next, the laser scanner unit 13a-
13d exposes the photosensitive drums 11a to 11d with a light beam such as a laser beam modulated in accordance with a recording image signal, thereby forming an electrostatic latent image thereon. Details of the operation of the laser scanner unit will be described later.
Further, the electrostatic latent image is visualized by the developing devices 14a to 14d which respectively store four color developers (hereinafter, referred to as toners) of yellow, cyan, magenta, and black. Cleaning devices 15a, 15b, 15c, 15 are provided on the downstream side of the image transfer areas Ta, Tb, Tc, Td for transferring the visualized visible image to the intermediate transfer member.
The photosensitive drums 11a to 11a are not transferred to the transfer material by d.
The toner left on d is scraped off to clean the drum surface. By the process described above, image formation with each toner is sequentially performed.

The paper feeding unit 20 includes cassettes 21a and 21b for storing the recording material P and a manual feed tray 27, and pickup rollers 22a and 22b for feeding the recording material P one by one in the cassette or from the manual feed tray.
6, a paper feed roller pair 23 and a paper feed guide 24 for conveying the recording material P sent from each pickup roller to the registration rollers, and a secondary transfer area of the recording material P in accordance with the image forming timing of the image forming unit. It consists of registration rollers 25a and 25b for feeding to Te.

The intermediate transfer unit 30 will be described in detail. The intermediate transfer belt 31 (the material thereof is, for example, P
ET [polyethylene terephthalate] and PVdF [polyvinylidene fluoride] are used) to apply an appropriate tension to the intermediate transfer belt 31 by a driving roller 32 for transmitting drive to the intermediate transfer belt 31 and a spring (not shown). The applied tension roller 33 and the driven roller 34 which faces the secondary transfer area Te with the belt interposed therebetween are wound around. Of these, the primary transfer plane A is formed between the drive roller 32 and the tension roller 33. The drive roller 32 is a metal roller whose surface is coated with rubber (urethane or chloroprene) having a thickness of several mm to prevent slippage with the belt. The drive roller 32 is rotationally driven by a pulse motor (not shown). In the primary transfer areas Ta to Td where the photosensitive drums 11a to 11d and the intermediate transfer belt 31 face each other, the primary transfer charger 35a is provided on the back of the intermediate transfer belt 31.
~ 35d are arranged. A secondary transfer roller 36 is arranged so as to face the driven roller 34, and forms a secondary transfer area Te by a nip with the intermediate transfer belt 31. The secondary transfer roller 36 is pressed against the intermediate transfer body with an appropriate pressure. In addition, on the intermediate transfer belt, the secondary transfer area Te
A brush roller (not shown) for cleaning the image forming surface of the intermediate transfer belt 31 and a waste toner box (not shown) for storing waste toner are provided downstream of the above.

The fixing unit 40 has a fixing roller 41a having a heat source such as a halogen heater therein, a pressure roller 41b (which may also have a heat source), and a nip portion of the roller pair. The guide 43 includes a guide 43 for guiding the transfer material P to, and an inner paper discharge roller 44 and an outer paper discharge roller 45 for further guiding the transfer material P discharged from the roller pair to the outside of the apparatus.

The control unit comprises a control board and a motor drive board (not shown) for controlling the operation of the mechanism in each unit.

Further, the environment sensor 50 is arranged at the position shown so that the environment temperature and humidity around the apparatus can be accurately measured without being affected by the fixing unit 40 which is a heat source in the apparatus. Various controls are performed based on the sensor output.

Next, the structure of the laser scanner unit will be described below with reference to FIGS.

First, the four laser scanner units 13
a to 13d are arranged as shown in FIG. The same unit is used for each of these four units.
It corresponds to four colors of ow, Mazenta, Cyan, and Black. There is no particular regulation regarding the order of arrangement. Further, in FIG. 2, the laser scanner unit is positioned vertically to the photosensitive drum, but it may be positioned horizontally without using the reflecting mirror 106, and the laser optical path may be L-shaped.

Next, the inside of the laser scanner unit will be described in detail with reference to FIG. This figure shows the case where the laser optical path is L-shaped. Reference numeral 102 is a rotary polyhedron, and 103 is a laser scanner motor that rotationally drives the rotary polyhedron 102. The number of faces of the rotating polyhedron 102 is determined by parameters such as print speed and resolution. A laser diode 101 is a recording light source. The laser diode 101 is turned on or off according to an image signal or a control signal by a drive circuit (not shown), and the light-modulated laser light emitted from the laser diode 101 is emitted toward the rotating polyhedron 102.

The rotating polyhedron 102 is rotating in the direction of the arrow, and the laser light emitted from the laser diode 101 is reflected by the reflecting surface of the rotating polyhedron 102 as a modified beam whose angle is continuously changed. The reflected light undergoes correction of distortion and the like by a lens group (not shown) and scans in the main scanning direction of the photosensitive drum 11 via the reflecting mirror 105. One surface of the rotating polyhedron 102 corresponds to scanning of one line, and the laser light emitted from the laser diode 101 by the rotation of the rotating polyhedron 102 is one line at a time on the photosensitive drum 1.
1 in the main scanning direction.

Further, a BD sensor 52 is arranged to generate a scanning start position reference signal in the main scanning direction. In reality, ideally, it should be installed near the scanning start position (near the photosensitive drum 11), but by using the folding mirror 107, the BD sensor 52 is arranged in the laser scanner unit. That is, the laser light reflected by each reflecting surface of the rotating polyhedron 102 is detected by the BD sensor 52 before scanning one line. The detected BD signal is used as a scanning start reference signal in the main scanning direction, and the writing start position of each main scanning line is synchronized with this signal as a reference. Further, using the signal output from the BD sensor 52, phase control and rotation speed control of the laser scanner motor are performed.

Next, FIG. 4 is a block diagram showing a scanner motor control section which is a feature of the present invention, and the specific control will be described below.

A brushless motor is used as the laser scanner motor 103, and the inside of the broken line shows its equivalent circuit. The inductance 205 is star-connected and excited by the bridge circuit 200 to generate a rotating magnetic field. A magnetic pattern is magnetized on the rotor 204,
Rotation is performed by the rotating magnetic field of the inductance 205 to drive the rotation of the rotating polyhedron 102. Further, it is a configuration of an oil moving body bearing. The hall elements 201 to 203 are the rotor 20.
The magnetic field magnetized in 4 is detected, and the detected magnetic field is input to the rotating magnetic field control circuit 206. The rotating magnetic field control circuit 206 detects the rotational position of the rotor 204 based on the output signals of the Hall elements 201 to 203, and constantly detects the rotor 204.
Bridge circuit 2 to generate a magnetic field that causes rotational movement
00 is controlled. Further, an acceleration signal and a deceleration signal from the acceleration / deceleration control unit 207 are input to the rotating magnetic field control circuit 206, and the rotation control of the motor is performed based on the signals, thereby performing speed control and further phase control.

During normal image formation, the BD switching controller 60 controls the output signal of the BD sensor 52 to be input to the acceleration / deceleration controller 207 based on the image formation start signal generated by the controller 57. The rotation control of the scanner motor is performed based on the BD signal. Here, particularly in the characteristic part of the first embodiment, when the temperature around the apparatus detected by the environment sensor 56 is a predetermined value or less and the standby state continues for a predetermined time, the control unit 57 Forcibly laser scanner motor 103
A signal for starting the driving is generated, and based on the signal, a pseudo BD signal generation unit 59 generates a BD signal having a cycle substantially equal to the output signal from the BD sensor 52 during normal image formation.
The output is generated as a pseudo BD signal and input to the acceleration / deceleration control unit 207. As a result, the scanner motor is steadily rotated without turning on the laser. Then, the scanner motor 103 is rotationally driven for a predetermined time and then stopped. When an image formation start signal is input to the control unit 57 while the scanner motor is forcibly driven, the normal image formation operation mode is entered. When the image formation is completed, the standby state is entered, and the above control based on the environmental temperature detected by the environmental sensor 56 is performed again. Since the detailed control of the acceleration / deceleration control unit 207 is not directly related to the present invention,
Omit it.

Next, the flow of the control sequence that characterizes the first embodiment will be described below with reference to the flowchart of FIG.

First, the apparatus is in a standby state (501).
Upon entering, it is determined whether or not the ambient temperature around the device is below a predetermined temperature T [° C] (50).
2). If it is higher than T ° C, the standby state is maintained as it is. On the other hand, when it is below T ° C, Timer
The operation of -1 is started (503), and it is monitored how long the apparatus is left in the standby state in the environment of T ° C or lower. Then, it is judged whether or not the leaving time has reached a predetermined time m1 (504), and the predetermined time m1 is reached.
If the value reaches, the scanner motor is forcibly started regardless of the print start instruction. Further, at this time, a pseudo BD signal is generated in order to control the steady rotation of the scanner motor while the laser is off, and the rotation of the scanner motor is controlled (505). By doing so, the rotation of the scanner motor can be controlled by turning off the laser, so that the deterioration of the photosensitive drum due to the laser light can be prevented. When the forced drive is started, the time is displayed to monitor the time during which the scanner motor is forced to drive.
r-2 operates (506). The scanner motor is driven until Timer-2 reaches the predetermined time m2 (510). When the predetermined time m2 is reached, the scanner motor is stopped and the process returns to the standby state (501). on the other hand,
A print start instruction (50
7), the scanner motor forced drive mode is shifted to the normal image forming operation (508) to form an image. Then, when it is finished (509), the process returns to the standby state (501).

(Second Embodiment) Each scanner unit 13 of the image forming apparatus according to the first embodiment shown in FIG.
An image forming apparatus according to the second embodiment, which has a configuration in which a temperature sensor is arranged at a position close to a scanner motor (not shown) provided in a to 13d, will be described below. In the first embodiment, the basic operation described with reference to FIG.

Now, the scanner motor control section in the second embodiment will be described with reference to the block diagram shown in FIG. The description similar to that of the first embodiment is omitted.

The difference from the first embodiment is that the temperature of the scanner motor is detected and controlled by the scanner motor temperature sensor 63 instead of monitoring the environmental temperature around the apparatus. The control during normal image formation is the same as in the first embodiment.

The feature of this embodiment is that when the temperature detected by the scanner motor temperature sensor 63 is equal to or lower than the predetermined temperature T1 and the apparatus is in the standby state, the controller 57 forces the controller 57 to perform a forced operation. A signal for starting driving the laser scanner motor 103 is generated in the pseudo BD signal generation unit 59, and a BD signal having a cycle substantially equal to the output signal from the BD sensor 52 during normal image formation is generated based on the signal. , Output as a pseudo BD signal, and input to the acceleration / deceleration control unit 207. As in the first embodiment, this causes the scanner motor to rotate steadily without turning on the laser. And
The scanner motor 103 is rotationally driven until the temperature of the scanner motor reaches a predetermined temperature T2. In addition, the image forming start signal is sent to the control unit 57 while the scanner motor is forcibly driven.
When the input is made, the operation shifts to the normal image forming operation mode. When the image formation is completed, the standby state is entered, and the above control based on the temperature detected by the scanner motor temperature sensor 63 is performed again.

Next, the flow of the control sequence that characterizes the second embodiment will be described below with reference to the flowchart of FIG.

First, when the apparatus enters the standby state (701), it is determined whether or not the scanner motor temperature is below a predetermined temperature T1 (702). If it is higher than the predetermined temperature T1, the standby state (701) is maintained, but if it is lower than the predetermined temperature T1, the scanner motor is forcibly driven. Also, at this time, in order to rotate the scanner motor steadily with the laser off, a pseudo BD
Generates a signal to control the rotation of the scanner motor (7
03). By doing so, the deterioration of the photosensitive drum due to the laser light can be prevented as in the first embodiment. And the scanner motor temperature

[Outer 1]

The scanner motor is rotationally driven until the value reaches (707). However, when the printing operation is started during the forced driving (704), the mode shifts to the normal image forming operation mode (705). Then, when the image formation is completed (706), the process returns to the standby state (701) and the above series of operations are repeated. And so on.

[0034]

As described above, according to the present invention, particularly in an oil-based polygon motor, by reducing and stabilizing the viscosity change of the oil in a low temperature environment, the polygon motor is started at the time of first printing. It is possible to suppress the time delay, and in particular, in the image forming apparatus in which the activation time of the polygon motor affects the first print time, it is possible to perform the image output with a stable first print time.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a color image forming apparatus according to the present invention.

FIG. 2 is a layout view of four optical units.

FIG. 3 is a perspective view showing the configuration of an optical unit in detail.

FIG. 4 is a control block diagram of the laser scanner motor according to the first embodiment of the present invention.

FIG. 5 is a flowchart showing a flow of operations according to the first exemplary embodiment of the present invention.

FIG. 6 is a control block diagram of a laser scanner motor according to a second embodiment of the present invention.

FIG. 7 is a flowchart showing a flow of operations according to the second embodiment of the present invention.

Claims (4)

[Claims] 1. A rotating polyhedron comprising a plurality of reflecting surfaces for reflecting a laser beam and having a bearing having a temperature characteristic, and a reflected light from the rotating polyhedron is received to perform main scanning on an image carrier. An image forming apparatus including a BD sensor that outputs a reference signal serving as a reference of a line writing start position, and a drive control unit that rotationally drives the rotating polyhedron at a predetermined cycle based on the reference signal. An environment measuring unit that measures the environment (temperature and humidity) around the forming device, and if it is left in a predetermined environment for a predetermined time or more without performing an image forming operation, it is forcibly forced regardless of the image forming start instruction. Inter-job drive control means for rotationally driving the rotating polyhedron. 2. The image forming apparatus according to claim 1, further comprising pseudo reference signal generating means for generating a pseudo reference signal having a cycle equivalent to that of the reference signal without using a BD sensor. When the rotational polyhedron is rotationally driven by the inter-job drive control means, the rotational cycle is controlled based on the pseudo reference signal. 3. A rotating polyhedron comprising a plurality of reflecting surfaces for reflecting a laser beam and having a bearing having a temperature characteristic, and a reflected light from the rotating polyhedron is received to perform main scanning on an image carrier. An image forming apparatus comprising: a BD sensor that outputs a reference signal serving as a reference for a line writing start position; and a drive control unit that rotationally drives the rotary polyhedron based on the reference signal. When the temperature measurement means for measuring the temperature and the temperature detected by the temperature measurement means are equal to or lower than a predetermined temperature T1, the rotary polyhedron is forcibly driven to rotate regardless of an image formation start instruction, Temperature T2
And a rotary body temperature control means for continuing the rotary drive until the temperature reaches. 4. The image forming apparatus according to claim 3, further comprising pseudo reference signal generating means for generating a pseudo reference signal having a cycle equivalent to that of the reference signal without using a BD sensor. When rotating the rotating polyhedron forcibly in the rotating body temperature control means, the rotation cycle is controlled based on the pseudo reference signal.