JPS5873276A - Optical scanning controller for laser beam printer - Google Patents

Abstract

PURPOSE:To improve the print speed with a simple means, by controlling a drive signal for a mirror motor rotating a scanning mirror and an optical modulation signal of a laser light source with a clock signal generated at a printer controller. CONSTITUTION:A clock signal is outputted from a printer controller 8 and inputted to a counter 12a. When the clock from the counter 12a is inputted to a clock synthesis circuit 11, mirror motor drive clocks phi1, phi2 and phi3 are outputted from the circuit 11. The clocks phi1, phi2 and phi3 drive a mirror motor 9. Further, a laser light source 7 is controlled with a print data D from the printer controller 8.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser beam printer, and more particularly to a laser beam scanning control device.

FIG. 1 is an optical system diagram showing an example of a conventional laser beam printer. 1 is a photosensitive drum, 2 is a reflective mirror, 5Fi
A photodetector, an ald scanning lens, 5 a hexagonal scanning mirror with 6 reflective surfaces, 6 a condensing lens, 7 ft, and a laser light source equipped with a modulator. That is, the laser beam emitted from the laser light source 7 is focused by the optical lens 6 and is incident on the reflective surface of the scanning mirror 5. Since the scanning mirror 5 is rotating, the laser beam reflected from its reflective surface passes through the scanning lens 4 and moves between the dashed and dotted lines.The area between the pair of dashed and dotted lines is the entire scanning area of the laser beam. The area between the pair of two-dot chain lines is an effective scanning area, and the modulation of the laser beam during this area is the photosensitive drum 1 rotating at a constant speed.
recorded as a latent image. A laser beam printer attaches toner to this latent image using a developing device (not shown), transfers it to a sheet of paper, develops it, and then brings it into close contact with the sheet of paper using a fixing device for blitting. That is, information is recorded using electronic photography.

A small reflecting mirror 2 and a photodetector 5 are installed outside the effective scanning area, and detect optical signals six times each time the scanning mirror 5 rotates once.

FIG. 2 is a block diagram of an irradiation control system using signals from the photodetector shown in FIG. 1. When light is detected by the photodetector 6, the signal a is outputted to the printer control device 8, and the light intensity of the laser light source 7 is changed by the laser light modulation signal from the splitter control device 18. That is, complex information is recorded while synchronizing the signals recorded in the effective scanning area of the photosensitive drum 1.

FIG. 6 is a time chart of the photodetection signal a and the laser beam modulation signal S shown in FIG. After a time t1 after the photodetector 5 detects the laser beam, the print data is output as a light modulation signal, and the transmission ends after a certain period of time. Thereafter, after a short pause, the laser light source 7 is excited after t2 hours to generate a laser light of a certain intensity. That is, the time t1 is the time from the solid line in Figure @1 to the left-hand dashed-dotted line, and the time t2 is the time from the solid line to the right-hand dashed-dotted line.

By repeating such control, scanning and modulation of the laser beam are automatically controlled.

However, the conventional Lebbeam printer has two reflecting mirrors.
In addition, a photodetector 6 is required, and its installation requires complicated support members and installation space, resulting in a large and expensive device.

Further, since the entire scanning area of the laser beam extends beyond the photosensitive drum 1, there is a drawback that scanning takes time and printing efficiency is low.

The present invention aims to eliminate the drawbacks of the above-mentioned prior art and provide a laser beam pre-/re light scanning control device that can improve printing speed by relatively simple means, and its features are as follows: The present invention is constructed so that the drive signal for the mirror motor that rotates the scanning mirror and the optical modulation signal for the laser light source are controlled by a clock signal suddenly generated by the printer control device.

FIG. 4 ta+ is an optical system diagram of an optical scanning control device that is an embodiment of the present invention, and FIG. 4 (1)) is a side view of the scanning mirror 5. The same parts as in FIG. As shown in the attached figure, since the reflecting mirror 2 and the photodetector 6 are removed in this case, the structure of the device is simplified. Note that the scanning mirror 5
is directly connected to the mirror motor 9, which is the same as in the conventional case.

FIG. 5 is a block diagram of the control circuit of the optical scanning control device of FIG. 4, and FIG. 6 is a time chart of the control circuit of FIG. 5. The clock signal output from the splitter control device i18 has a clock period six times that of the clock output from the counter i2a'6>.

Note that 6 times this value corresponds to the fact that the reflection surface force of the scanning mirror 5 is 61, and the reflection surface force of the scanning mirror 5 is 81. When this clock input is input to the clock configuration circuit 11, the mirror motor drive clocks φ1, φ2, and φ3 are outputted from this circuit 25.

The mirror motor driver 10 is operated by the clocks φ1, φ2, and φ3 to drive the mirror motor 9. In addition, the mirror motor 9 is a di-phase motor, and the upper 5 clock A
It is configured so that it rotates 11 times in 12 clocks.

As described above, since the scanning mirror 5 has six reflecting surfaces, one rotation of the mirror motor 9 scans the scanning area between one point and the line six times. The counter 12b in FIG. 5 is a hexadecimal counter, and outputs the clock B from this counter.

FIG. 6(1)) shows an enlarged view of one period ta of the clock B, and when the clock B is input to the delay circuit 13 in FIG. 5, a scanning start signal C is output. This scan start signal C is set to rise with a delay of t (1 hour) from the rise of clock B, and this delay time td is 0 to 1 hour.
It can be changed between ta.

In response to the scanning start signal Of, the splitter control device t8 in FIG.
Print data D is output from. In addition, in Fig. 6 (bl), the print data D is written at the ON signal, but it is natural that it is actually an ON and OFF signal.Also, the above delay time td can be changed greatly. Therefore, it is easy to match the scanning start signal C with the dashed dotted line on the left side of FIG.

The optical scanning control mounting of this embodiment provides the following effects.

(1) Since the conventional reflecting mirror 2 and photodetector 5 are omitted and the optical scanning area is reduced, the configuration is simple, small and inexpensive, and printing efficiency is improved.

(2) - Driving the mirror motor using mechanical control means 1
Since the light source is modulated by generating the control signal for the printer and the light source, it can operate at high speed and with high precision, greatly increasing the printing capacity.

-1: In the example, a 5-phase motor was used as the mirror motor 9, but the invention is not limited to this, and any type 7 motor can be used as long as it rotates in synchronization with a clock. Can be used. Further, although the number of reflective surfaces of the scanning mirror 5 was six in the embodiment, it is not limited to this number and can be set arbitrarily. When the number of surfaces is n, if color/re+2a in FIG. 5 is used as an n-ary counter, control similar to that described above becomes possible. Furthermore, the mirror motor 9
The clock A in FIG. 6 counts 12 clocks while it rotates, but if it is constructed so that it rotates once every m clocks, the same control can be performed as the counter 12 in FIG. Can be done.

Since the optical scanning control device for a laser beam printer of the present invention configures the scanning start signal within the control device, the mechanical structure is simple, small and inexpensive, and the printing speed 1 can be increased. is obtained.

[Brief explanation of drawings]

Figure 1 is an optical system diagram showing an example of a conventional laser beam printer. Figure 2 is a block diagram of the irradiation control system using the signal from the photodetector in Figure 1, Figure 6 is a time chart of the photodetection signal a and the laser beam modulation signal in Figure 2, and Figure 4 is the diagram of the present invention. 2 is an optical time chart that is an example of the above. DESCRIPTION OF SYMBOLS 1... Photosensitive drum, 4... Scanning lens, 5... Scanning lens, 6... Condensing lens, 7... Laser light source,
8...Printer control device, 9...Mirror motor, 1
0...Mirror motor driver, 11...Clock synthesis circuit, 12...Counter, 15...Delay circuit. Patent applicant name Hitachi Koki Co., Ltd.

Claims (1)

[Claims] t A laser beam generated from a laser light source is reflected by a plurality of side surfaces of a rotating polygonal scanning mirror, and by irradiating and scanning the rotating photosensitive drum surface with the reflected light, the photosensitive drum F is scanned. In a laser beam printer that records a light modulation signal of the laser light source, a drive signal of a mirror motor that rotates an eclipse mirror and F
1. An optical scanning control device for a laser beam pre/receiver, characterized in that the optical modulation signal of the laser light source is controlled by a clock signal generated by a pre-control device.