JPS6259462A - Semiconductor laser scanner - Google Patents

Abstract

PURPOSE:To easily modulate the strength of an optical beam by providing plural semiconductor laser light sources, a drive circuit capable of individually turning on and off these light sources and an image forming optical system matching light beams from the plural laser beams. CONSTITUTION:Semiconductor laser 11a, 11b...11n are individually turned on and off respectively by drive circuits 12a, 12b...12n. The light beams Ra, Rb...Rn from the respective semiconductor lasers 11a, 11b-11n are transmitted or reflected by half mirrors of half prisms Ma, Mb-Mn of image forming systems and matched to one light Ro. The finally matched light beam Ro scans a recording surface or a display surface through a deflecting system. In this case, the modulation of the strength of the light beam is carried out for instance by turning on the laser 11a, and turning off the other and the modulating strength can be changed by changing a set value of a current of the respective semiconductor lasers.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a semiconductor laser scanning device applied to a laser beam printer or the like.

(Prior Art) As shown in FIG. 2, an electrostatic latent image carrier 1 such as a recording medium
is rotating in the direction of the arrow, and a charger 2, a developer 3, a transfer device 4, and a cleaning unit 5 are arranged around it, and a light beam modulated by an information signal is transmitted through a deflection spring 6 and a reflection mirror 7. An electrostatic latent image obtained by projecting onto the electrostatic latent image carrier surface (hereinafter referred to as recording surface) 1 is visualized by a developing device 3 and recorded on a transfer paper 8 by a transfer device 4. So-called laser beam printers are in practical use.

By the way, as a method for modulating the intensity of a light beam in such a laser beam printer, focusing on the fact that a semiconductor laser has an I-L characteristic in which the amount of output light changes depending on the injection current, injection into a semiconductor laser is performed. Intensity modulation of a light beam is known in which the amount of output light is changed by controlling the current.

However, the I-L characteristics of a semiconductor laser have a strong temperature dependence, and furthermore, the characteristics vary greatly depending on the device due to the non-uniformity of the composition of the semiconductor laser, so it has been very difficult to control the amount of output light by the injection current.

(Objective) The present invention was made in order to solve the above-mentioned problems, and an object of the present invention is to provide a semiconductor laser scanning device that can easily perform intensity modulation of a light beam.

(Configuration) FIG. 1 is a configuration diagram showing an example of a semiconductor laser scanning device of the present invention. In this figure, reference numeral 11a.

11b, . . . lln indicate semiconductor lasers, and each of the semiconductor lasers lla, ILL, . There is. Each semiconductor laser 11a.

The light beams Ra, Rb, . . . from 11b, .
A light beam R is transmitted by Mb and reflected by Mb.

is consistent with In this case, it goes without saying that the light beam Rn from the semiconductor laser lln located at the rightmost end in the figure is reflected by the reflecting mirror Mn and is aligned with the light beam RO like the other light beams Ra, Rh... do not have.

Then, this finally aligned light beam Ro is transferred to a deflector 6
(See FIG. 2) to scan the recording surface or display surface.

Next, in order to perform intensity modulation of the light beam, for example, turn on the semiconductor laser lla, and turn on the other semiconductor lasers 11b,
. . . lln may be turned off, or semiconductor lasers lla and llb may be turned on and the others may be turned off. In addition, the modulation intensity of each semiconductor laser Lla, ll
b, . . . Lln can be freely changed by changing the set value of the current value, and it is easy to control the output light amount at each lighting time to be constant. Furthermore, this control method can use a known method of feeding back the amount of error from the light amount detection circuit to the semiconductor laser drive circuit, making it possible to easily modulate the intensity of the light beam.

(Effects) As is clear from the above explanation, the present invention has the effect of easily modulating the intensity of a light beam and making it possible to express multiple gradations in a laser beam printer. It is something.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a schematic block diagram showing a laser beam printer. 11a, llb, . . . 1ln-・semiconductor laser, 1
2a, 12b, "...12n...Drive circuit, M
a r M b 7...Mn...Imaging optical system+
Ra, Rb,...Rn...Each light beam, Ro...
...aligned final light beam.

Claims (1)

[Claims] In a semiconductor laser scanning device in which a modulated light beam from a semiconductor laser is imaged onto a recording surface or a display surface by an imaging optical system, a plurality of semiconductor laser light sources are used, and each of these semiconductor laser light sources is turned on independently. - A semiconductor laser scanning device comprising: a drive circuit that can be turned off; and an imaging optical system that aligns light beams from the plurality of semiconductor laser light sources.