JP2004181904A - Laser beam output correction control method for electrophotographic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam output correction control method for an electrophotographic device, which maintains the output level of laser beams to a constant value before and after exchange of print heads, to thereby obtain good printing quality and reliability of a suitable laser light source. <P>SOLUTION: There is provided a laser light source device having the laser light source for emitting laser beams on a predetermined optical path, which is comprised of an optical path switching means, a light detecting means, a laser output control means, and a memory means. The optical path switching means is arranged on a first optical path which is the aforementioned predetermined optical path, and leads the laser beams to a second optical path different from the first optical path. The light detecting means is arranged on the second optical path, for detecting the output level of the laser beams. The laser output control means controls the output level of the laser beams, based on an output from the light detecting means. The memory means stores therein the detected output level of the laser beams and a control correction value for obtaining the output level. The laser light source device automatically detects that a printing head as one of component part exchange units, and corrects the output level of laser beams as needed, to thereby maintain the output level to the constant value. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to laser beam output correction control of an electrophotographic apparatus provided with a laser light source that emits a laser beam.
[0002]
[Prior art]
FIG. 4 is a schematic diagram showing a laser scanning device provided with a conventional laser light source device. The print head 28 in the laser light source device 26 includes a laser light source 15 made of a semiconductor laser, and the laser light source 15 is driven by the laser drive circuit 14. The laser drive circuit 14 modulates the laser beam 3 according to a print information signal supplied from an external information processing device. The laser light source 15 has a built-in sensor (not shown) for detecting the output level of the laser beam 3, and the output of the sensor is input to the auto power control circuit 17. Further, the auto power control circuit 17 connected to the laser drive circuit 14 controls the laser drive circuit 14 so that the sensor output becomes constant, so that the laser beam 3 having a constant output level is output from the laser light source 15. Be injected. The laser beam 3 passes through the collimator lens 18, becomes parallel light, is reflected by the rotating polygon mirror 19 rotating at high speed in the direction of arrow b, passes through the Fθ lens 20, and scans the surface of the photosensitive drum 1. By repeatedly scanning the surface of the rotating photosensitive drum 1, an electrostatic latent image is formed on the uniformly charged surface of the photosensitive drum 1.
[0003]
The laser beam output is periodically corrected to prevent a change in the amount of laser light on the photosensitive drum 1 due to contamination of the collimator lens 18 and the like provided on the optical path between the laser light source 15 and the photosensitive drum 1. Perform control. That is, during the printing operation, the reflecting mirror 21 is disposed at a position retracted from the first optical path 1a (see FIG. 2) which is a predetermined optical path, so that the laser beam 3 is placed on the first optical path 1a. That is, since the light is emitted to the rotating polygon mirror 19, an electrostatic latent image is formed on the surface of the photosensitive drum 1.
[0004]
Next, during the operation of detecting the output level of the laser beam 3, the reflecting mirror 21 is disposed at a position inserted on the optical path 1a, so that the laser beam 3 is reflected by the reflecting mirror 21 and the second optical path 1b (See FIG. 2), and irradiates the photodetector 24. The output value of the light detection element 24 at this time is taken into a laser output control circuit 25, and the value is set to a predetermined target value (the light when the laser beam of the target output level is irradiated on the light detection element 24). The laser power command signal for determining the output level transmitted from the laser output control circuit 25 to the automatic power control circuit 17 is varied so as to be equal to the output value of the detection element 24). The correction value for changing is recorded in the memory A27, and this correction value is used until the next correction trigger. The trigger for performing the operation of detecting the output level of the laser beam 3 is a non-printing state (laser light source) after a printing time has passed a specified time in a cycle in which the amount of laser light on the photoreceptor 1 obtained from an experiment does not change. (A state in which no beam is emitted from the light source).
[0005]
Accordingly, even when the output level of the laser beam on the photosensitive drum 1 is reduced due to contamination of the collimator lens 18 provided on the optical path and the laser light source emission port, the state can be detected. Thus, the output level of the laser beam can be kept constant.
[0006]
[Problems to be solved by the invention]
However, since the memory A27 and the print head 28 are composed of different parts, when the print head 28 is replaced, the correction value of the laser beam output level stored in the memory A 27 before the print head 28 is replaced is used. When the laser light source 15 is driven, there arises a problem that a print quality defect occurs, or an improper load is applied to the laser light source 15, and the reliability of the laser light source 15 becomes lower than its actual ability.
[0007]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a laser light source for an electrophotographic apparatus capable of maintaining a constant output level of a laser beam before and after replacing a print head and obtaining good print quality and appropriate laser light source 15 reliability. It is to provide a device.
[0008]
[Means for Solving the Problems]
The object is to provide an electrophotographic apparatus including a laser light source that irradiates a laser beam, and a laser light source device that emits the laser beam onto a first optical path that is a predetermined optical path. Optical path switching means provided on the first optical path for guiding to a second optical path different from the first optical path; and light detecting means provided on the second optical path for detecting an output level of the laser beam. Laser output control means for controlling the output level of the laser beam based on the output level of the light detection means, and means for storing the output level of the detected laser beam and a control correction value for obtaining the output level. Achieved by automatically detecting that the print head, which is one of the component replacement units, has been replaced, correcting the laser beam output level as necessary, and keeping it constant. It is.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to FIGS. In this figure, the same parts as those in FIG. 4 are denoted by the same reference numerals.
[0010]
FIG. 1 shows the overall configuration of the electrophotographic apparatus. Reference numeral 1 denotes a photosensitive drum that forms a toner image by an electrophotographic process, and is supported by a spindle so as to rotate at a constant speed in the direction of arrow a. The charger 2 is arranged so as to face the surface of the photosensitive drum 1, and uniformly charges the surface of the photosensitive drum 1 passing so as to face the charger 2. The laser beam 3 for exposing the uniformly charged surface of the photosensitive drum 1 is modulated in accordance with a print information signal supplied from an information processing device to form an electrostatic latent image on the surface of the photosensitive drum 1. The developing device 4 is disposed so as to face the surface of the photosensitive drum 1 on which the electrostatic latent image has been formed. The developing device 4 has a developing function of forming a toner image by causing fine powder toner to adhere to the surface of the photosensitive drum 1 with electrostatic force of the electrostatic latent image. The paper hopper 7 accommodates a continuous band-shaped recording material (printing paper) 6 for transferring and fixing the toner image and performing image printing in a folded state. Conveyance rollers 8a and 8b constituting a part of the print paper conveyance means take in the print paper 6 from the hopper 7 and send it out toward the photosensitive drum 1. The printing paper 6 sent from the transport rollers 8a and 8b comes into contact with the surface of the photosensitive drum 1 so as to transfer the toner image to the surface. The transfer device 5 generates an electrostatic force for moving (transferring) the toner image to the surface of the printing paper 6 on the back surface of the printing paper 6 in contact with the surface of the photosensitive drum 1. Conveyance rollers 9a and 9b which form another part of the sheet conveyance means feed the printing paper 6 onto which the toner image has been transferred to the preheater 10. The preheater 10 is installed at a position on the front side of the fixing roll 11 and preheats the printing paper 6 by contacting the back surface of the printing paper 6 holding the toner image.
[0011]
The preheater 10 has a configuration in which, for example, an electric heating element is attached to the back surface of the heat transfer member with which the back surface of the printing paper 6 contacts, and the preheater 10 applies the printing paper 6 while the printing paper 6 moves while contacting the front surface. The printing paper 6 is heated to such an extent that the attached toner image is softened. The temperature of the preheater 10 is adjusted by controlling the current supplied to the electric heating element by the temperature control device 16.
[0012]
A pair of fixing rolls 11 composed of a heating roll 11a and a pressure roll 11b pressed against the heating roll 11a heat and pressurize the pre-heated printing paper 6 in contact with the pre-heater 10 to form a toner image on the printing paper 6. Settles on the surface. Inside the puller rollers 12a and 12b, the printing paper 6 sent out from the fixing roll 11 is drawn in, folded and accommodated in the stacker 13, or discharged outside the machine, and a second electrophotographic apparatus arranged at a subsequent stage or a rear electrophotographic apparatus. Or a processing device (not shown).
[0013]
FIG. 2 shows the configuration of the laser light source device according to the present invention. A support arm 22 having a reflecting mirror 21 attached to the tip is connected to a rotating shaft of a motor 23. The reflecting mirror 21 is provided at a position where the laser beam 3 emitted from the laser light source 15 can be inserted into the optical path 1a after the laser beam 3 passes through the collimator lens 18 and becomes parallel light. It is possible to arrange the reflecting mirror 21 at a position where the reflecting mirror 21 is inserted on the first optical path 1a, or at a position where the reflecting mirror 21 is retracted from the optical path 1a.
[0014]
The light detecting element 24 is disposed on the second optical path 1b through which the laser beam 3 reflected by the reflecting mirror 21 is guided when the reflecting mirror 21 is inserted on the optical path 1a.
[0015]
Next, the operation will be described with reference to FIG. During the printing operation, the reflecting mirror 21 is disposed at a position retracted from the optical path 1a, so that the laser beam 3 is emitted on the optical path 1a, that is, to the rotating polygon mirror 19, so that the laser beam 3 An electrostatic latent image is formed.
[0016]
Next, in the operation of correcting the output level of the laser beam, in order to detect the output level of the laser beam 3, the reflecting mirror 21 is disposed at a position inserted on the optical path 1a. The light is guided to the optical path 1b, and irradiates the light detecting element 24. The output value of the light detection element 24 at this time is taken into a laser output control circuit 25, and a predetermined target value (the light detection element 24 when the laser beam of the target output level is irradiated on the light detection element 24) is obtained. The laser power command signal for determining the output level transmitted from the laser output control circuit 25 to the automatic power control circuit 17 is changed so as to be equal to the output value of the laser power control circuit 25. The correction value for changing is recorded in the memory A27 and the memory B29 in the print head 28. The laser light source 15 is driven using the correction value of the memory B29 until the next correction trigger. When the power of the electrophotographic apparatus is turned on, the correction values of the laser beam outputs stored in the memories A27 and B29 are compared. If they are not the same, it is considered that the print head 28 has been replaced, and the laser beam output correction operation is performed. I do.
[0017]
As a result, even if the print head is replaced, the output of the laser beam can be kept constant, and good print quality and appropriate laser light source reliability can be obtained.
[0018]
【The invention's effect】
As described above, according to the present invention, it is possible to keep the output level of the laser beam constant before and after replacing the print head, thereby obtaining good print quality and appropriate reliability of the laser light source.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the overall configuration of an electrophotographic apparatus.
FIG. 2 is a perspective view of a main part showing a laser light source device according to the present invention.
FIG. 3 is a block diagram of a laser light source device control system according to the present invention.
FIG. 4 is a block diagram of a conventional laser light source device control system.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum, 1a ... 1st optical path, 1b ... 2nd optical path, 2 ... Charger, 3 ... Laser beam, 4 ... Developing device, 5 ... Transfer device, 6 printing paper, 7 hopper, 8a, 8b, 9a, 9b transport roller, 10 preheater, 11a heat roller, 11b pressure roller, 12a, 12b: puller roller, 13: stacker, 14: laser drive circuit, 15: laser light source, 16: temperature control device, 17: automatic power control circuit, 18 ... Collimator lens, 19: rotating polygon mirror, 20: Fθ lens, 21: reflecting mirror, 22: support arm, 23: motor, 24: photodetector, 25 ... Laser output control circuit, 26 laser light source device, 27 ... memory A, 8 ... print head, 29 ... memory B.

Claims (1)

An electrophotographic apparatus including a laser light source that irradiates a laser beam, and a laser light source device that emits the laser beam onto a predetermined optical path, wherein the laser beam is different from a first optical path that is the predetermined optical path An optical path switching means provided on the first optical path for guiding to a second optical path; a light detecting means provided on the second optical path for detecting an output level of the laser beam; A laser output control unit for controlling an output level of the laser beam based on an output; and a unit for storing a detected output level of the laser beam and a control correction value for obtaining the output level, and a component replacement unit. One of the features of the electrophotographic apparatus is that it automatically detects that the print head has been replaced, corrects the laser beam output level as needed, and keeps it constant. Zabimu output correction control method.

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