JPH02198413A - Optical wiring device for laser printer or the like - Google Patents

Abstract

PURPOSE:To contrive the cost-down by simplifying the structure and the assembly work by providing a holder for holding a cylindrical lens so as to be freely movable in the optical path length direction and so as to be freely turnable around the axis center being parallel to its optical path length direction. CONSTITUTION:A holder 35 for holding a cylindrical lens 26 is provided so as to be freely movable in the optical path length direction and so as to be freely turnable around the axis center being parallel to its optical path length direction. Accordingly, by displacing the holder 35 together with the cylindrical lens 26 in the optical path length direction, the diameter of a laser light in the sub-scanning direction is minimized, and by turning the holder 35 together with the cylindrical lens 26, a bus of the cylindrical lens 26 is made parallel to a bus of an ftheta lens 28. Also, by fixing the cylindrical lens 26 to one holder 35 having a moving mechanism and a turning mechanism in the optical path length direction, the number of parts can be decreased. In such a way, by simplifying the structure and the assembly work, the cost-down can be contrived.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical writing device such as a laser printer.

Conventional technology FIG. 8 shows the basic arrangement of optical elements in the optical path from the LD unit 25 to the oPC belt 8. The laser beam from the LD unit 25 passes through the cylindrical lens 2.
6, is reflected by the reflecting surface of the rotating polygon mirror 27, and is further scanned through the fθ lens 28 onto the PC belt 8 as a photosensitive surface. At this time, the diameter d of the laser beam in the sub-scanning direction (paper passing direction) is narrowed down by the cylindrical lens 26 and the fO lens 28. Further, the diameter of the laser beam in the main scanning direction perpendicular to the sub-scanning direction is narrowed down by the FE lens 28. In order to minimize the diameter of the laser beam in the sub-scanning direction, the cylindrical lens 26 must be moved in the optical path length direction, and the generatrix of the cylindrical lens 28 must be adjusted to be parallel to the generatrix of the FE lens. .

Conventionally, as shown in FIG. 9, a cylindrical second holder 102 is rotatably provided on a first holder 101 that is slidably held in a housing 100.
2, the first holder 101 is moved in the optical path length direction to minimize the diameter of the laser beam in the sub-scanning direction, and the second holder 102 is moved in the optical path length direction. By rotating around parallel axes, the angle of the generatrix 103 of the cylindrical lens 26 with respect to the generatrix of the fθ lens 28 is adjusted with an accuracy of 10' order.

Problems to be Solved by the Invention Conventionally, the second holder 102 rotates together with the cylindrical lens 26, and the first holder 101 displaces the second holder 102 together with the cylindrical lens 26 in the optical path length direction. Since two holders 101 and 102 are required, and a structure for supporting these holders 101 and 102 is required, the number of parts increases. In addition, variations are added due to the increase in the number of parts, and variations in the relative positions of the cylindrical lens 26 and the fθ lens 28 become large, resulting in problems such as increased costs.

Means for Solving the Problems In an optical writing device such as a laser printer in which a laser beam irradiated from a light source through a cylindrical lens is reflected by a scanning unit and scanned on a photosensitive surface through an FCL lens, a holder holding the cylindrical lens is used. It is provided to be movable in the optical path length direction and rotatable around an axis parallel to the optical path length direction.

By displacing the working holder together with the cylindrical lens in the optical path length direction, the diameter of the laser beam in the sub-scanning direction is minimized, and by rotating the holder together with the cylindrical lens, the generatrix of the cylindrical lens is adjusted to f.
e parallel to the generatrix of the lens. Further, by fixing the cylindrical lens to one holder having a movement mechanism in the direction of the optical path length and a rotation mechanism, the number of parts can be reduced.

Embodiment An embodiment of the present invention will be explained based on FIGS. 1 to 7. FIG. 7 is a side view showing the internal mechanism of the laser printer. In the figure, 1 is a housing, and at the bottom of this housing L,
A paper feed cassette 2, a paper feed roller 3 that pulls out the paper in the paper feed cassette 2, and a power source 4 are arranged. An engine drive board 6 and a controller board 7 are arranged, and an OPC belt 8, which is a photosensitive surface, is connected to a motor and rotatably held in the center of the housing 1. There are 200 PCs around this ○PC belt 8.
A charger 9 that charges the belt 8, an optical unit 10 that forms a latent image on the portion charged by the charger 9, and a developing unit 13 that includes a toner cartridge 11 and a developing roller 12 and develops the latent image. and O
A transfer charger 14 that transfers the developed image on the PC belt 8 to paper, a cleaning unit 15 that wipes off residual toner on the OPC belt 8, and a static elimination lamp 16 that erases the latent image on the OPC belt 8 are arranged. There is. Furthermore, in the paper feed path from the paper feed tray 5 to the transfer charger 14, a pickup roller 17, a grip roller 18, and a registration roller are provided so as to sequentially convey the paper on the paper feed tray 5. 19 are arranged.

Further, in the paper ejection path downstream of the paper feed path, a belt 20 for conveying the paper, a hot roller 21, a pressure roller 22, a paper ejection roller 23, and an fD paper ejection unit 24 are sequentially arranged. has been done. 25a is a heat radiation duct.

Next, the structure of the optical unit 10 will be explained with reference to FIGS. 4 and 5. FIG. 4 is a side view, and FIG. 5 is a plan view. As is clear from these figures, the LD which is the light source
unit 25, cylindrical lens 26, rotating polygon mirror 27 as a scanning section, fθ lens 28, first mirror 29, second mirror 30, and third mirror 31
are arranged in the optical path. In addition, a second mirror 30
An information recording device 32 is disposed on the reflected optical path of the optical fiber cable 33.
It is connected to the synchronization detection unit 34 via. The arrangement of optical elements in the optical path is as shown in the block diagram of FIG.

Next, the support structure of the holder 35 to which the cylindrical lens 26 is fixed is shown in FIGS. 1 and 2. 1st
The figure is a plan view, and FIG. 2 is a side view seen from the direction of arrow B in FIG. As shown in FIG.
A stepped screw 38 is loosely fitted into the holder 35, a compression spring 38 is wound around the stepped screw 37, and an adjusting screw 39 whose tip abuts against the housing 36 is provided at the end of the holder 35. They are screwed together. Therefore, the holder 35
receives the biasing force of the compression spring 38 via the washer 41, and by turning the adjustment screw 39, it is rotated in the optical path length direction using the abutting portion between the edge 40 on the opposite side of the adjustment screw 39 and the housing 36 as a fulcrum. It is supported so that it can rotate about parallel axes. Furthermore, for example, a stepped screw 37
The holder 35 is held movably in the optical path length direction (in the direction of the arrow in FIG. 1) by forming a long hole in the holder 35 that is slidably fitted in the optical path length direction. There is. That is, the holder 35 has a moving mechanism in the optical path length direction and a rotation mechanism that rotates in the optical path length direction. The mechanism for moving the holder 35 in the optical path length direction is
For example, the housing 36 is configured by providing a push screw (not shown) for pressing the holder 35. In addition,
FIG. 3 shows the shape of the cylindrical shins 26 when viewed from the direction of arrow C in FIG.

In such a configuration, when the laser beam is irradiated from the LD unit 25 to the rotating polygon mirror 27 through the cylindrical lens 26 during the process of rotating the rotating polygon mirror 27,
This laser beam is scanned by a rotating polygon mirror 27, and this scanning beam is reflected multiple times by a first mirror 29 and a second mirror 30, and then is reflected by a third mirror 31 onto the OPC belt 8. , an electrostatic latent image is written on the OPC belt 8. On the other hand, the information recording device 32 is irradiated with the scanning light that deviates from one end of the third mirror 31 . The optical information input to the information recording device 32 is input to the synchronization detection unit 34 via an optical fiber cable 33.

Although the laser beam is scanned as described above, the holder 35 is moved along with the cylindrical lens 26 in the optical path length direction (first
The diameter of the laser beam in the sub-scanning direction can be adjusted to a minimum of 8 by displacing the laser beam in the direction indicated by the arrow in the figure. At this time, since the holder 35 receives pressure from the compression spring 38 via the washer 41 and the edge 40 is pressed against the housing 36, the holder 35 can be kept stationary at any position in the optical path length direction. Furthermore, as the adjustment screw 39 is tightened to increase the length of the protrusion of the tip from the holder 35, the holder 35 rotates in the upright direction about the abutment between the edge 40 and the housing 36, and the adjustment screw 39 is rotated in the opposite direction. By turning the holder 35 in the direction shown in FIG. As a result, the generatrix 42 of the cylindrical lens 26 is aligned a in parallel to the generatrix of the ff9 lens 28.

As described above, by fixing the cylindrical lens 26 to one holder 35 having a movement mechanism in the optical path length direction and a rotation mechanism about an axis parallel to the optical path length direction, the number of parts can be reduced. The number can be reduced.

Effects of the Invention Since the present invention is configured as described above, the diameter of the laser beam in the sub-scanning direction is minimized by displacing the holder together with the cylindrical lens in the optical path length direction, and the holder is rotated together with the cylindrical lens. This allows the generatrix of the cylindrical lens to be parallel to the generatrix of the fθ lens, and also includes a movement mechanism in the optical path length direction and a rotation mechanism around an axis parallel to the optical path length direction. By fixing the cylindrical lens to one holder having a cylindrical lens, it is possible to reduce the number of parts, thereby simplifying the structure and assembly work and reducing costs.

FIG. 2 is a side view of the cylindrical lens seen from the direction of arrow B in FIG. 1, and FIG. 3 is a front view of the cylindrical lens seen from the direction of arrow C in FIG. 2. Figure 4 is a side view of the optical unit, Figure 5 is a plan view of the optical unit, Figure 6 is a block diagram showing the arrangement of optical elements in the optical path, and Figure 7 is a side view showing the internal structure of the laser printer. 8 is an explanatory view showing the basic arrangement of optical elements in the optical path from the light source to the photosensitive surface, and FIG. 9 is a side view showing the support structure of a conventional cylindrical lens.

25...Light source, 26...Cylindrical lens, 27...Scanning section, 28...Fθ lens, 35...Holder

[Brief explanation of the drawing]

Claims (1)

[Claims] In an optical writing device such as a laser printer, in which a laser beam irradiated from a light source through a cylindrical lens is reflected by a scanning unit and scanned onto a photosensitive surface through an fθ lens, a holder holding the cylindrical lens is movable in the optical path length direction. An optical writing device, such as a laser printer, characterized in that it is rotatably provided around an axis parallel to the optical path length direction.