JPH02184812A - Image forming device - Google Patents

Abstract

PURPOSE:To always form excellent image information by permitting at least one mirror, which is closer to a photosensitive plane, among plural reflecting mirrors to be a displacable optical path length adjusting mirror and adjusting the optical path length to the photosensitive body. CONSTITUTION:The reflecting mirrors 3 and 4 are positioned so as to permit (a) < (b), when the distance between the reflecting mirror 3 and the photosensitive body 5 is (b) and the distance between the reflecting mirror 4 and the photosensitive body 5 is (a). The reflecting mirrors 11 and 12 are fixed and the reflecting mirror 4, which is closest to the photosensitive body 5, is displaced in the arrowed direction as the optical path length adjusting mirror. Then the optical path length of luminous flux A is changed and the scanning widths in the sub scanning directions by the two luminous flux A and B formed on the plane of the photosensitive body 5 are adjusted. Thus, all the horizontal scanning widths based on the plural laser beam flux are easily equalized and the excellent image is formed without image deviation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an image forming apparatus, and particularly to an image forming apparatus that uses a plurality of laser beams modulated by signals based on image information from a computer, facsimile, document reading device, or word processor. An image forming apparatus that guides light to a rotating polygon mirror as a light scanning means and rotates the rotating polygon mirror to simultaneously scan a plurality of positions on a photoreceptor surface of a photosensitive drum list and form image information. It is related to.

(Prior Art) Conventionally, an image forming apparatus using a light beam modulated based on image information, such as a light beam from a semiconductor laser, was disclosed in Japanese Patent Laid-Open No. 6
This method has been proposed in JP-A No. 1-13759, Japanese Unexamined Patent Publication No. 57-102609, and the like.

FIG. 3 is a schematic diagram of main parts of a conventional image forming apparatus. In the image forming apparatus shown in the figure, image information is converted into current pulses, a plurality of modulated light beams are emitted from a light source 100 such as a semiconductor laser, and the plurality of light beams are focused in a predetermined direction by a cylindrical lens 101. Rear rotation multi-faceted fit 0
The light flux is deflected by a rotating polygon mirror 102 which is rotated at a constant speed, and then guided onto a photoreceptor surface 103 such as a photoreceptor drum through an f-theta lens 104. Scanning multiple locations simultaneously.

Image information is formed on the photoreceptor surface 103 while continuously rotating the photoreceptor 103 in a sub-scanning direction perpendicular to the main-scanning direction.

In the figure, reference numeral 105 is a mirror, and reference numeral 106 is a photodetector, which receives a portion of the laser beam to obtain a horizontal synchronization signal.

As shown in FIG. 3, image information can be efficiently formed on a photosensitive surface by using a plurality of laser beams in a conventional image forming apparatus.

However, due to manufacturing errors, the optical path length of each light beam to the photoreceptor surface is different, and the horizontal scanning width on the photoreceptor surface is different, so if images are produced based on each light beam, There was a problem that the image width shifted and the image quality deteriorated.

(Problems to be Solved by the Invention) Is the present invention modulated based on image information? When forming image information by simultaneously scanning the photoconductor surface with I number of laser beams incident on different positions on the photoconductor surface, at least one folding mirror placed near the photoconductor surface is used to adjust the optical path length. By having a movable structure that can adjust the width of the laser beam, the scan width in the main scanning direction (horizontal scanning direction) when forming image information on the photoreceptor surface using multiple laser beams can be adjusted. It is an object of the present invention to provide an image forming apparatus that can always form good image information.

(Means for Solving the Problems) The present invention deflects a plurality of light beams modulated based on image information by a light scanning means, and then deflects each light beam to different beams on the photoreceptor surface via at least two folding mirrors. an optical path length capable of displacing at least one mirror on the side closer to the photoreceptor surface among the plurality of folding mirrors when guiding light to a position and simultaneously scanning the photoreceptor surface with a plurality of light beams to form image information; It is characterized by being an adjustable mirror, which allows the length of the optical path up to the photoreceptor to be adjusted.

In particular, the optical path length adjusting mirror is characterized in that its inclination can be adjusted in the direction of the central axis of the scanning light beam and in the direction perpendicular to the central axis.

(Embodiment) FIG. 1 is a schematic diagram of a main part of an embodiment of an image forming apparatus of the present invention.

In the figure, l denotes an optical unit that emits a plurality of laser beams modulated based on image information, in the figure two laser beams A and B.

The optical unit l includes a light source that emits a plurality of laser beams modulated based on image information, a drive circuit that drives and controls the light beams from the light source based on the image information, and a scanning device that deflects the plurality of laser beams in a predetermined direction. It houses optical scanning means and the like.

A laser beam A from the optical unit 1 is reflected by two folding mirrors 11.4, and then is incident on the surface of the photoreceptor 5. Further, the laser beam B is reflected by the two folding mirrors 12.3 and then is incident on the surface of the photoreceptor 5.

In this embodiment, when the distance from the folding mirror 3 to the photoconductor 5 is b, and the distance from the folding mirror 4 to the photoconductor 5 is a, the folding mirror 3.4 is adjusted so that a<b.
are placed.

Then, the folding mirrors 11 and 12 are fixed, and the photoreceptor 5
The folding mirror 4 closest to is used as an optical path length adjustment mirror and is displaced in the direction of the arrow. By changing the optical path length of the laser beam A, the scanning width in the sub-scanning direction by the two beams A and B formed on the surface of the photoreceptor 5 is adjusted.

In this embodiment, the photoreceptor 5 of the folding mirror is
The optical path length of the folding mirror 4 closest to the mirror 4 can be adjusted. That is, a mirror that can easily make fine adjustments on the surface of the photoreceptor 5 in response to parallel movement of the folding mirror, that is, a mirror that moves a large amount of mirror movement but moves only slightly on the drum, is used as the optical path length adjustment mirror. There is.

Further, by adopting such a configuration, even if the folding mirror 2, for example, changes slightly due to vibration or the like, there is no change in the scanning width on the surface of the photoreceptor 5 at all.

In this embodiment, the folding mirror 3 is constructed so that it can be tilted and shifted.

In this embodiment, when the optical path length is changed by displacing the optical path length adjustment mirror 4, the position where the laser beam A is incident on the surface of the photoreceptor 5 changes. Therefore, the tilt of the optical path length adjusting mirror is made adjustable.

In other words, the configuration is such that the inclination of the scanning light beam can be adjusted in the direction of the central axis (optical axis) 13 and in the direction orthogonal to the central axis 13, so that the inclination of the laser beam A when the optical path length is changed is The incident position on the photoreceptor surface remains unchanged before and after adjusting the optical path length.

In this embodiment, the above-described configuration prevents image shift from occurring when image information is formed on the surface of the photoreceptor 5 by the two laser beams A and B.

FIG. 2 is a schematic diagram of an embodiment showing a method of displacing the optical path length adjustment mirror 4 of FIG. 1.

Figures (A), (B), and (C) are a front view, a top view, and a right side view, respectively.

In the figure, 37 is an immovable member, 37a and 37a are a pair of bottles installed vertically on the outer surface of the immovable member, and 25 is a translation plate applied to the outer surface of the immovable member, and the surface of the erroneous translation plate 25 is is a pair of upper and lower bottles 37a and 37a on the above-mentioned immovable member surface.
Guide elongated holes 2 whose lengths are in the vertical direction into which they are fitted and engaged, respectively.
5a and 25a, and guide elongated holes 25b and 25b provided on the left and right sides of which the longitudinal direction is the vertical direction, and this guide elongated hole 2
The parallel moving plate 25 is attached to the stationary member 37 by inserting setscrews 25c and 25c into the fixed screws 5b and 25b and screwing them into the screw holes 37b (37b) on the stationary member 37 side. By loosening the setscrews 25c and 25c, the parallel moving plate 25 is aligned with the fixed member 37 through the long holes 25b and 25b.
It can be moved vertically in parallel within the length range of , and can be fixed at the parallel movement position by tightening the screws 25c.

Reference numeral 25d denotes a right angle bent plate portion provided in series on the upper side of the parallel displacement plate 25. 25e, 25f, and 25g are three positioning screw pins screwed upward, two at one end of the plate at intervals and one at the other end; 22 is a mirror stopper plate; The mirror 4 is the stop member 22a
・It is fixed immovably at 22a. 22b and 22b are through holes formed on both ends of the long side of the mirror stopper plate 22;
1 is a set screw that is inserted into the through hole 22b, 22b and screwed into the screw hole 25b, 25b provided in the right angle bent plate portion 25dl, and 21a, 21a is the head of the set screw and the mirror stop plate. This is a biasing spring that is compressed between the upper surfaces of 22.

The mirror stopper plate 22 is bent at a right angle by the biasing spring mentioned above.
The receiver is pressed in the direction of 5d and is fixed to the lower surface or the L end of the three positioning screw pins 25e, 25f, and 25g.

By individually adjusting the screw holes of the three positioning screw bottles, the angle of inclination of the mirror stopper 22, that is, the mirror 4
The degree of inclination can be adjusted.

Therefore, the vertical translation position of the translation plate 25 and the above 3
By adjusting the inclination of the mirror 4 using the book racks 25e, 25f, and 25g, the optical path length to the photoreceptor 5 can be adjusted using the mirror 4 as an optical path length adjusting mirror. Then, the time during sub-scanning that hits the drum is changed.

(Effects of the Invention) As described above, according to the present invention, when forming image information on a photoreceptor surface by making a plurality of laser beams modulated based on image information enter different positions on the photoreceptor surface, Optical path length m with magnification adjustment function for folding mirrors like !
! ! By using a mirror, the horizontal scanning widths based on a plurality of laser beams can be easily made equal, and an image forming apparatus capable of forming a good image without image shift can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the main parts of one embodiment of the present invention, and FIG.
FIG. 3 is a schematic diagram of a conventional image forming apparatus. In the figure, 1 is an optical unit, 11.12.3 is a folding mirror, 4 is an optical path length adjustment mirror, 5 is a photoreceptor, 21 is a set screw, 22 is a mirror stopper plate, 23 is a set screw, 25 is a translation plate, 26 is a positioning bin.

Claims (2)

[Claims] (1) After deflecting a plurality of light fluxes modulated based on image information by an optical scanning means, each light beam is guided to different positions on the photoreceptor surface via at least two folding mirrors,
When forming image information by simultaneously scanning the surface of the photoreceptor with a plurality of light beams, at least one mirror closer to the photoreceptor surface among the plurality of folding mirrors is a displaceable optical path length adjustment mirror; An image forming apparatus characterized in that the length of an optical path up to a photoreceptor can be adjusted. (2) The image forming apparatus according to claim 1, wherein the optical path length adjusting mirror is configured so that its inclination can be adjusted in the direction of the central axis of the scanning light beam and in the direction perpendicular to the central axis.