JPH0229712A - scanning optical device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a scanning optical device that performs exposure scanning using a light beam, such as a laser beam printer.

(Prior Art) Conventionally, this type of scanning optical device is explained by taking a laser beam printer as an example. A rotating photoreceptor drum or belt-shaped Exposure scanning is performed on the photoreceptor in a line in a direction perpendicular to the direction of movement of the photoreceptor (hereinafter referred to as the main scanning direction). Then, exposure scanning is performed sequentially in the rotational direction of the photoreceptor (hereinafter referred to as the sub-scanning direction), and one image is formed as a collection of the scanning lines.

(Problems to be Solved by the Invention) However, in the case of such prior art, for example, the photosensitive drum is provided with a gear on the outer periphery of one end thereof, and is driven via a gear train provided on the main body side. Therefore, when the drum is driven to rotate, the spacing between adjacent scanning lines arranged in the sub-scanning direction varies due to, for example, a fine gear pitch, resulting in unevenness in the image.

The present invention has been made to solve the problems of the prior art described above, and its purpose is to enable exposure scanning while the image carrier is stationary, and to reduce the spacing between scanning lines by gear pitch etc. The purpose is to prevent image unevenness due to variations.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, an image bearing member that moves relative to the scanning unit is placed on the image carrier in a direction crossing the moving direction. In a scanning optical device that performs image exposure sequentially in a moving direction while scanning a beam in a line, the exposure scanning surface of the image carrier is a flat surface, and the scanning unit is moved while the image carrier is stationary to expose the image. It is characterized by being provided with a moving means for scanning.

(Function) Thus, while the scanning unit scans the beam on the image carrier, the scanning unit is moved by the moving means, and images are sequentially exposed on the exposure scanning surface on the image carrier.

(Example) The present invention will be described below according to illustrated embodiments. In FIGS. 1 and 2 showing a scanning optical device according to an embodiment of the present invention, 1 is an endless image carrier. It is a belt-shaped photoreceptor, and is wound between a pair of rollers 5 and 6 that are arranged parallel to each other with a predetermined distance apart. One roller 6 is rotationally driven by a motor 22.

A pre-exposure device 12. -Next charger 1
1. Developing sleeve 21. A toner container 7, a waste toner cleaning container 20, and a transfer charger 9 are provided, and images are formed by a known electrophotographic process.

The photoreceptor 1 has an exposure scanning surface 4o whose upper surface side is flat, and a polygon scanner imaging system 4 as a scanning unit is disposed above the photoreceptor 1 at a predetermined distance from the exposure scanning surface 4o. has been done.

The polygon scanner imaging system 4 is movable along the guide rail 2 in the direction of movement of the photoreceptor 1 parallel to the exposure scanning surface 4o of the photoreceptor 1.
The movement is controlled by

The moving means 50 is constituted by a wire drive mechanism. That is, the polygon scanner imaging system 4 is fixed to a wire 14, and this wire 14 is wound around a driving pulley 15 and a driven pulley 13, and is rotated through the wire 14 by the rotation of a motor 16 directly connected to the driving pulley 15. The polygon scanner imaging system 4 is moved in the direction indicated by the arrow in the figure.

The polygon scanner imaging system 4 includes a laser emitting section 18. Polygon mirror 17. A mirror 19 and the like are provided, and the laser beam emitted from the laser emitting section 18 is scanned onto the photoreceptor.

The laser light emitted from the laser emitting unit 18 is scanned in the main scanning direction (direction of the rotation axis of the photoreceptor 1) on the stopped photoreceptor 1 by the rotation of the polygon mirror 17. Furthermore, the rotation of the motor 16 causes the driving force to be applied to the pulley 15.
The laser beam is transmitted to the wire 14, moves the polygon scanner imaging system 4 fixed to the wire 14 in the direction A, and performs scanning in the sub-scanning direction.

The polygon scanner imaging system 4 slides smoothly along the guide rail 2 during movement, and can obtain high-definition images without variations in the spacing between scanning lines.

After the photoreceptor 1 finishes scanning one page of paper, the rotation of the motor 22 transmits power to the roller 6, causing the photoreceptor 1 to rotate. After being developed by the developing sleeve 21, the image is transferred onto the paper 8 by the transfer charger 9, fixed by the fixing device 10, and then discharged.

3 and 4 show a second embodiment of the invention. Components that are the same as those in the first embodiment will be described with the same reference numerals. In this embodiment, an ultrasonic motor 30 is used as a moving means for the polygon scanner imaging system 4.
is used.

The ultrasonic motor 30 is composed of a piezoelectric element 23 and a stator 26, the polygon scanner imaging system 4 is placed on the stator 26 via a contact surface 25, and the piezoelectric element is placed below the stator 26. 23 is glued. The contact surface 25 is a rigid body made of aluminum, for example. Further, 24 is a guide rail for guiding the polygon scanner imaging system 4.

By applying an alternating current voltage to the piezoelectric element 23, vibrations having a frequency in the ultrasonic range are generated, and the vibration energy moves the polygon scanner imaging system 4 to the guide rail 24.
, and sub-scanning is performed in the same manner as in the first embodiment.

If such an ultrasonic motor 30 is used, there is no need for space for wires or the like as in the first embodiment, so the device can be made more compact.

In addition to the ultrasonic motor 30 described above, it is also possible to use a general linear motor that utilizes electromagnetic force.

Furthermore, in the above embodiment, a scanning unit using a laser light source was described, but other scanning units may be used, such as those using an LED array or a liquid crystal shutter array, which digitally expose and scan each pixel using a light beam. It is widely applicable to

(Effects of the Invention) The present invention has the above-described configuration and operation, and the image carrier is kept stationary and the scanning unit side is moved to perform exposure scanning. It is possible to prevent blurring of the image due to unevenness, and it is possible to obtain an effect that it is possible to form a high-quality image.

[Brief explanation of the drawing]

FIG. 1 is a front view showing a schematic configuration of a scanning optical device according to a first embodiment of the present invention, FIG. 2 is a schematic plan view of the device shown in FIG. 1, and FIG. FIG. 4 is a front view showing a schematic configuration of such a scanning optical device, and FIG. 4 is a schematic side view of the device shown in FIG. 3. Explanation of symbols 1...Photoreceptor 2...Guide rail 4...Polygon scanner imaging system 5.6...
Roller 13.15...Pulley 23...Piezoelectric element 26...Stator 14...Wire 16...Motor 24,...Guide rail 30...Ultrasonic motor

Claims (1)

[Scope of Claims] Scanning optics that sequentially exposes images in the moving direction while scanning a beam in a line in a direction intersecting the moving direction with the scanning unit on an image carrier that moves relatively to the scanning unit. A scanning optical device characterized in that the exposure scanning surface of the image carrier is a flat surface, and a moving means is provided for moving the scanning unit to perform exposure scanning while the image carrier is stationary.