JPH11249052A - Optical scanning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical scanning device with which an electrostatic latent image can be recorded and formed on a body to be scanned such as a photosensitive drum with stable laser light intensity by arranging a temperature detecting means near an optical element driving means and driving a cooling means based on the output of the temperature detecting means. SOLUTION: An optical element driving device 4 is provided with a temperature detecting sensor 6 for detecting the temperature of the optical element driving device 4. Besides, a cooling device 7 such as a fan is provided near the optical element driving device 4. The cooling device 7 is driven by feeding back information detected by the temperature detecting sensor 6. The cooling device 7 can be stepwisely adjusted by the setting of an external resistor 8. Thus, since the temperature detecting sensor 6 and the cooling device 7 are provided near the optical element driving device 4, the temperature information is fed back from the temperature detecting sensor 6, the number of rotations of the cooling device 7 is stepwisely changed corresponding to the temperature information, and the optical element driving device 4 is cooled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device used in an electrophotographic apparatus such as a laser printer and a copying machine, and more particularly to an optical element for diffractively modulating a laser beam and an optical element for driving the optical element. The present invention relates to an optical scanning device provided with element driving means.

[0002]

2. Description of the Related Art The prior art will be described with reference to FIG. Laser light emitted from a laser light source (not shown) enters the optical element 5 and is subjected to diffraction modulation based on print data developed by a control device (not shown), and then an arbitrary modulation order light is selected. The modulated light is a rotating polygon mirror 1 that rotates at a constant speed.
And scans the photosensitive drum 3 through the Fθ lens 2 to form an electrostatic latent image on the photosensitive drum 3.

The optical element 5 is generally known as an acousto-optical element, and drives an oscillator attached to an element formed of TeO ₂ or the like by an oscillator, that is, an optical element driving device 4, and generates an ultrasonic wave in the optical element 5. And modulates the laser light. Further, the optical element driving device 4 transmits to the optical element 5 print data developed by a control device (not shown), that is, a modulation output at a carrier oscillation frequency according to the carrier wave.

[0004]

SUMMARY OF THE INVENTION Optical element driving device 4
Has an input / output characteristic in which the output power is reduced as shown in FIG. 3 with a rise in temperature such as self-heating of the optical element 5. On the other hand, in the optical element 5, the modulation efficiency, that is, the intensity of the emitted light of any modulation order changes depending on the input power. In other words, the intensity of the laser beam emitted from the optical element 5 depends on the temperature state of the optical element driving device 4, for example, at the beginning of printing when the temperature of the optical element driving device 4 is low, and when the temperature of the optical element driving device 4 is high. In the latter period, the laser beam intensity changes, and as a result, a problem such as a change in print density occurs.

It is an object of the present invention to provide an optical scanning device capable of recording and forming an electrostatic latent image on a scanned object such as a photosensitive drum with a stable laser beam intensity.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical scanning apparatus having an optical element for diffractively modulating a laser beam and an optical element driving means for driving the optical element. This is achieved by having a temperature detecting means for detecting the temperature, and a cooling means arranged near the optical element driving means and driven based on the output of the temperature detecting means.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In addition, the same reference numerals are given to members equivalent to those in the related art, and description thereof is omitted.

[0008] The optical element driving device 4 is provided with a temperature detecting sensor 6 for detecting the temperature of the optical element driving device 4. A cooling device 7 such as a fan is provided near the optical element driving device 4. The cooling device 7 is driven by feedback of information detected by the temperature detection sensor 6. The cooling device 7 can be adjusted stepwise by setting the external resistor 8. The temperature of the optical element driving device 4 has a temperature dependence of the input / output characteristics of the optical element driving device shown in FIG.

By providing the temperature detecting sensor 6 and the cooling device 7 near the optical element driving device 4 as described above, feedback of temperature information from the temperature detecting sensor 6 is performed.
The optical element driving device 4 is cooled by changing the rotation speed of the cooling device 7 stepwise according to the temperature information by setting the external resistor 8.

[0010]

As described above, according to the present invention, the temperature detecting means for detecting the temperature of the optical element driving means, and the temperature detecting means disposed near the optical element driving means and driven based on the output of the temperature detecting means. The provision of the cooling means makes it difficult for the laser light intensity to change due to the temperature change of the optical element driving means. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an optical scanning device of the present invention.

FIG. 2 is a schematic configuration diagram of a conventional optical scanning device.

FIG. 3 is an explanatory diagram relating to temperature dependence of input / output characteristics of an optical element driving device.

FIG. 4 is an explanatory diagram showing a relationship between output power and a rotation speed of a cooling device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rotating polygon mirror, 2 ... F (theta) lens, 3 ... Scanned object (photosensitive drum), 4 ... Optical element drive device, 5 ... Optical element, 6 ...
Temperature detection sensor, 7: cooling device, 8: external resistance.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigeo Nemoto 1060 Takeda, Hitachinaka-shi, Ibaraki Prefecture Within Hitachi Koki Co., Ltd.

Claims (1)

[Claims] 1. An optical scanning apparatus comprising: an optical element for diffractively modulating a laser beam; and an optical element driving means for driving the optical element, wherein a temperature detecting means for detecting a temperature of the optical element driving means; An optical scanning device comprising: a cooling unit disposed near the optical element driving unit and driven based on an output of the temperature detecting unit.