JPH01105905A - Optical scanner - Google Patents

Abstract

PURPOSE:To correct the scanning distortion so that a satisfactory picture drawing quality can be obtained in the whole scanning area by providing a beam splitter on the whole area on a scanning line and placing a sensor for detecting the scanning distortion of one light beam which has been split. CONSTITUTION:Between a photosensitive drum 13 and an image forming lens 14, a beam splitter 15 and a beam position detecting sensor 16 are provided extending over the whole area on a scanning line. A light beam which has been reflected by a rotary polygon mirror 12 passes through the image forming lens 14, split into two roughly vertically by the beam splitter 15, and one light beam is made incident on the detecting sensor 16, and blurring in the vertical direction against the scanning direction, namely, a scanning distortion is detected by the sensor 16. Subsequently, in accordance with its distortion quantity, an input frequency to an acousto-optical element 11 is adjusted by a controller 17, and by correcting the scanning distortion, recording on the scanning surface is executed. Therefore, since the distortion is detected in a real time and the correction is executed, a satisfactory picture drawing quality is obtained in the whole area on the scanning line.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical scanning device, and particularly to an optical scanning device having means for correcting original scanning distortion.

[Conventional technology]

As a conventional technique, for example, Japanese Patent Application Laid-Open No. 60-232770
As disclosed in the above publication, there is an optical scanning device that corrects scanning distortion by installing a sensor near the starting end on the main scanning axis.

A conventional optical scanning device includes an optical deflector that adjusts the optical axis, a scanning position detector installed near the starting end on the main scanning axis, inputs the output from the detector, and deflects the optical beam according to the input. and a controller that adjusts the carrier frequency of the device.

Next, a conventional optical scanning device will be explained with reference to the drawings.

FIG. 3 is a perspective view showing a conventional optical scanning device.

A laser beam from a laser oscillator 1 is modulated by an acousto-optic element 2 used as a light modulator and a light deflector, main-scanned by a rotating polygon mirror 3, passes through an imaging lens 4, and forms an image on a photoreceptor drum 5. At this time, the photosensitive drum 5 is rotationally driven to perform sub-scanning and record on a two-dimensional plane.

The amount of scanning distortion of the main scanning line due to axial vibration of the rotating polygon mirror 3, etc.
While correcting the scanning distortion by adjusting the input frequency to the acousto-optic element 2 by the controller 7 according to the amount of scanning distortion detected by the scanning position detector 6 installed near the starting end of the main scanning line, Recording is performed on the scanning surface.

[Problem that the invention seeks to solve]

The conventional optical scanning device described above corrects scanning distortion only near the scanning start end. However, scanning distortion due to surface tilt and axial vibration of the rotating polygon mirror.

Since the distortion occurs randomly from the start of the scan to the center to the end, conventional optical scanning devices have the disadvantage that the drawing quality deteriorates due to scanning distortion in areas other than the start of the scan.

[Means for solving problems]

The optical scanning device of the present invention includes a light source, a main scanning means for scanning a surface to be scanned using a rotating polygon mirror as scanning light using light emitted from the light source, and a main scanning means for scanning a surface to be scanned in a direction perpendicular to the main scanning direction. A sub-scanning means for driving a surface, an optical deflector for correcting surface inclination of the rotating polygon mirror, an optical modulator for modulating the scanning light according to an image signal, and a light splitter installed on the entire scanning optical path. and is installed on the optical path divided approximately perpendicularly to the original axis of the scanning light by the optical splitter, and covers the entire area of the divided scanning optical path, and detects scanning distortion occurring in the direction perpendicular to the scanning direction. and means for correcting the scanning light according to the amount of scanning distortion detected by the sensor.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of the present invention.

The optical scanning device shown in FIG. 1 scans a light source 10, light 20 emitted from the light source 10, an acousto-optic element 11 that modulates and deflects the light 20 according to an image signal input from the outside, and a source 20. a rotating polygon mirror 12 for forming an image on the photosensitive drum 13 from the light scanned by the rotating polygon mirror 12; a splitter 15; a beam position detection sensor 16 installed on the optical axis 21 split by the light splitter 15;
It is configured to include a controller 17 that processes the output of the beam position detection sensor 16 and inputs it to the acousto-optic element 11.

Light 20 emitted from the light source 10 is modulated and deflected by the acousto-optic element 11 and enters the rotating polygon @12. The light reflected by the rotating polygonal mirror 12 passes through the imaging lens 14 and is divided into two parts at approximately right angles to each other by the one-element splitter 15. One optical axis forms an image on the photoreceptor drum 14, and the other optical axis forms an image on the photoreceptor drum 14. enters the beam position detection sensor 16. Beam position detection sensor 16
Then, the pre-scanning distortion and the pinching scanning distortion in the direction perpendicular to the scanning direction are detected, and a voltage proportional to the amount of distortion with respect to the target value is outputted and inputted to the controller 17. The controller 17 deflects the multiple optical axes by adjusting the frequency for driving the acousto-optic element 11 according to the input voltage, thereby correcting scanning distortion in real time over the entire scanning line.

FIG. 2 is a side view showing the state of generation and detection of scanning distortion.

If scanning is performed with an optical axis that is deviated by θ from the ideal original axis 20 due to the rotation axis runout and surface tilt of the rotating polygon mirror 12, a scanning distortion of dl will occur on the photosensitive drum, causing a problem in the drawing quality. The light splitter 15 splits the scanning light 20 and the detection light 21, and the positional deviation ct of the detection light 21 is detected by the beam position detection sensor 16.
If detected by d2, since d and d are in a proportional relationship, d2
By performing correction according to the above, it is possible to obtain good drawing quality without scanning distortion.

〔Effect of the invention〕

In the optical scanning device of the present invention, instead of installing a sensor near the starting end of the scanning line, a light splitter is installed over the entire area on the scanning line, and the optical scanning device further scans one of the original scanning distortions divided by the light splitter. By providing a sensor that detects the entire scanning line, scanning distortion can be detected in real time across the entire scanning line, and correction can be made according to the detected amount of scanning distortion, resulting in good drawing quality over the entire scanning plane. There is an effect.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of the present invention, and FIG. 2 is a perspective view showing one embodiment of the present invention.
FIG. 3 is a side view of the optical scanning device shown in the figure, and FIG. 3 is a perspective view showing a conventional example. 1... Laser oscillator, 2.11... Foreword optical element,
3.12... Rotating polygon mirror, 4.13... Photosensitive drum, 5.17... Controller, 10... Light source, 1
4...Imaging lens, 15...Light splitter, 16...
Beam position detection sensor. Agent Patent Attorney Shin'o Uchihara Figure 1, 2nd indentation

Claims (1)

[Claims] a light source, a main scanning means for scanning a surface to be scanned using a rotating polygon mirror as scanning light emitted from the light source, and a sub-scanning means for driving the surface to be scanned in a direction perpendicular to the main scanning direction; an optical deflector that corrects surface tilt of the rotating polygon mirror;
an optical modulator that modulates the scanning light according to an image signal; a light splitter installed over the entire scanning optical path; a sensor installed to cover the entire area of the divided scanning optical path and detect scanning distortion occurring in a direction perpendicular to the scanning direction; and means for correcting the scanning light according to the amount of scanning distortion detected by the sensor. An optical scanning device comprising: