JP2003285468A - Laser control device - Google Patents

Abstract

[PROBLEMS] To obtain a BD output signal by scanning a BD sensor without scanning a photosensitive drum when a laser is turned on. SOLUTION: In an apparatus provided with a laser, a BD sensor, and a polygon motor with FG output, when the FG cycle becomes constant, the laser is turned on at a predetermined timing stored by a storage means for the FG output signal. A laser control device, characterized in that:

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for forming a latent image by scanning a photosensitive drum with a laser beam. [0002] A sensor for detecting a laser beam (hereinafter referred to as BD)
Image horizontal synchronization output signal (hereinafter referred to as BD)
Up to now, it has been necessary to turn on the laser at an indefinite timing after the polygon motor enters a stable rotation state and turn on the laser until the BD sensor is scanned. Therefore, by scanning the photosensitive drum for a maximum of several scans before scanning the BD sensor, the BD
Check the correlation between the position of the sensor and the polygon mirror,
Thereafter, the laser was controlled to be turned on before and after the BD sensor. However, when the laser is turned on at such a timing, the photosensitive drum is scanned for one to several scans, and there is a risk of damaging the surface layer of the photosensitive drum. As a countermeasure, by rotating the photosensitive drum before laser scanning to prevent at least the scanning of the stopped photosensitive drum, unevenness of the surface layer of the photosensitive drum is prevented and the life of the photosensitive drum is maintained. However, although the photosensitive drum is actually rotating, the APC (auto power supply) is stronger than a laser beam for forming a normal latent image.
When scanning with a control) level laser beam was repeated, the surface layer of the photosensitive drum caused considerable unevenness and shortened the life of the photosensitive drum. According to the present invention, there is provided, as one of means for solving the above problems, a laser for emitting a laser beam, and a method for scanning a photosensitive drum with the laser beam. A polygon motor control for driving a polygon mirror, and a sensor that outputs a horizontal synchronization signal of an image by detecting the laser beam, wherein an FG output signal when the polygon motor is in a stable rotation state; Means for storing a timing for turning on the laser at a predetermined timing with respect to the FG output signal; and turning on the laser at the timing stored in the storage means, causing the sensor to scan, and outputting the sensor. By turning off the laser after detecting a signal, the image is horizontally synchronized without scanning the photosensitive drum with the laser light. A signal can be obtained, and the surface layer of the photosensitive drum can be protected and its life can be extended. FIG. 1 is a diagram for explaining an embodiment of the present invention, and a description will be given below in accordance with specific operations. First, an exposure system of a printer having a laser will be described with reference to FIG. This printer scans a laser beam L1 internally modulated according to image data in parallel to the scanning direction of the drum 6 and records the laser beam L1 on the drum 6. In FIG. 6, the light emitted from the laser 1 is a laser beam L1 collected by a condenser lens 2 (hereinafter referred to as a collimator lens). The laser beam L1 is applied to the polygon mirror 3, is deflected, and passes through the imaging lens 4 to uniformly charge the surface of the drum 6.
Scanned up. The drum 6 is driven to rotate in synchronization with the scanning of the laser beam L1, and the laser beam L1 and the drum 6 move relatively in the sub-scanning direction to perform two-dimensional image recording. In this way, the laser light corresponding to the image data is scanned,
An electrostatic latent image is formed on drum 6. A toner charged in the opposite polarity adheres to the electrostatic latent image and development is performed, and an image is obtained by transferring the developed image onto recording paper. Here, the relationship between laser control and driving of a polygon motor according to the present invention will be described. In the conventional case, as shown in FIGS. 5 and 6, the laser is turned on at an indefinite timing β with respect to the FG output signal to detect the BD sensor, and the photosensitive drum 6 performs one scan to several scans. Was. Here, in the present invention, as shown in FIGS. 1 and 3, difference data α between the FG output signal and the BD detection signal, which has been measured in advance by factory adjustment to detect the BD sensor, is stored in the memory 9. After the polygon motor 7 reaches a certain rotation (FGLOCK signal detection), the laser is turned on at a timing according to the FG output signal and the difference data α of the memory, so that the laser beam is not scanned without scanning the photosensitive drum 6. By turning on the light, the surface layer of the photosensitive drum 6 can be protected and its life can be extended. Next, details of the present invention will be described based on embodiments. 2, the polygon motor driving unit 11 starts the polygon motor 7 to rotate the polygon mirror 3, and determines whether or not the output FG signal has a predetermined period. The FGLOCK signal flag is set by detecting that a certain period has been reached, and then the laser 1 is turned on at the timing of the delay data α set in the memory 9 for the FG signal via the laser driving unit 10. By turning off the laser after the laser is detected by the BD sensor 5, a BD detection signal can be obtained without scanning the photosensitive drum 6. Next, an operation chart of the present invention will be described with reference to FIG. In step 101 (S101), the polygon motor is driven. In S102, an FG signal output by rotation of the polygon is detected, and in S10
In step 3, the period of the FG signal is confirmed, and a comparison is made to determine whether the period has reached a predetermined period. If the comparison result in S103 matches, a predetermined laser lighting timing value is read into the memory in S104, and the laser is turned on at a timing shifted by the difference data α with respect to the FG signal in S105. In step S106, when the BD signal is detected by the laser scanning, the laser is turned off, and a series of scanning systems is terminated, so that a BD detection signal can be obtained without scanning the photosensitive drum. As described above, according to the present invention, the photosensitive drum is turned on at a predetermined timing with respect to the FG output signal when the polygon motor enters a stable rotation state. This makes it possible to obtain an image horizontal synchronizing signal without scanning the upper portion with the laser beam, thereby protecting the surface layer of the photosensitive drum and extending the life thereof.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a timing diagram representing the claims of the present invention. FIG. 2 is a block diagram showing the claims of the present invention. FIG. 3 is a diagram showing the claims of the present invention. FIG. 4 is a chart showing the claims of the present invention. FIG. 5 is a timing chart representing a conventional example. FIG. 6 is a diagram illustrating a conventional example. [Description of Signs] 1: Laser 2: Collimator lens 3: Rotating polygon mirror (polygon mirror) 4: Imaging lens 5: BD sensor 6: Drum 7: Polygon motor 8: Controller 9: Memory 10, Laser driving unit 11: Polygon motor drive unit 12: photosensitive drum drive unit L1: laser light

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H04N 1/113 H04N 1/04 104A F-term (Reference) 2C362 BA04 BA89 BB31 CB72 2H045 AA56 CB61 DA41 2H076 AB05 AB12 AB16 AB22 AB32 AB67 5C072 AA03 BA17 HA02 HA13 HB02 HB08 HB11 HB13 JA07 UA11 UA13

Claims (1)

1. A laser that emits laser light, a polygon motor control that drives a polygon mirror for scanning a photosensitive drum with the laser light, and an image that is detected by detecting the laser light. In an apparatus including a sensor that outputs a horizontal synchronization signal, an FG output signal when the polygon motor is in a stable rotation state, and a timing for lighting the laser at a predetermined timing with respect to the FG output signal. Means for storing, turning on the laser at the timing stored in the storage means, causing the sensor to scan, and turning off the laser after detecting the output signal of the sensor, whereby the laser light is irradiated on the photosensitive drum. 1. A laser control device comprising: means for obtaining an image horizontal synchronizing signal without scanning by a laser beam.