JPH0894897A - Optical scanner - Google Patents

Abstract

PURPOSE: To provide an optical scanner whose structure is simple, whose assembly is easy and which is provided with lens fixed structure immune to impact. CONSTITUTION: In a optical scanner having a deflecting means, fθlenses 6 and 7 and an optical housing 1; plural fθ lenses exist and oblique notches 9 are formed at least at the parts of the upper ends of the opposed surfaces of two lenses 6 and 7 out of the fθlenses, and projections 18 and 21 are formed on the outside of a position where two lenses 6 and 7 should be fixed on the optical housing 1. Furthermore, a lens pressing member 10 coming into contact with the notched surfaces of two lenses 6 and 7 simultaneously and pressing means 11 and 12 pressing the member 10 downward are provided in the scanner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens fixing structure in an optical scanning device such as a digital copying machine or a printer.

[0002]

2. Description of the Related Art Conventionally, as a fixing structure for an fθ lens of an optical scanning device, many fixing structures using screws or springs have been proposed. When the lens is fixed with screws, there is no risk of displacement due to vibration or shock, but there was the problem that assembly was extremely poor. That is, if the vertical direction is fixed, the horizontal position will not match, and if the horizontal direction is fixed, the vertical position will not match.
It was necessary to carefully fix both directions simultaneously. On the other hand, when the lens is fixed by a spring, the displacement can be easily eliminated by temporarily applying a force after the assembly.

Japanese Utility Model Publication No. 2-48813 discloses a lens fixing structure in which an elastic member for pressing the lens is attached to a rigid body extending over a side wall. As shown in FIG. 3 of the publication, this structure has a structure in which an elastic member presses the lens from above onto a protruding seat provided in the optical box. In such a structure, since the lens is supported by the elastic member, the position of the lens may be displaced when vibration, impact, etc. are applied, which is more significant when the lens is large and heavy. It becomes remarkable. When the lens is displaced from the predetermined position, it is held at the displaced position and is not restored.

As an improvement plan of the above conventional example, FIG.
A lens fixing structure as shown in (1) has been proposed. In this structure, the reference protrusions 19, 20 and 22, 23 for mounting the two lenses 6, 7 on the optical housing 1 are provided, and the protrusion 1 that abuts on one surface of each lens.
8 and 21 are provided, and the surface on the side opposite to the protrusion is provided with the spring 3 respectively.
It is structured to be pressed by 5, 32. 33, 34
Is a screw for fixing the spring to the housing. Further, the lenses are pressed downward by the spring 30 from above the lenses 6 and 7. With such a structure, even if the lens moves due to vibration, impact, etc., it can be restored to its original position by the force of the spring.

[0005]

In the conventional lens fixing structure as shown in FIG. 4, for example, when the pressing force Fy of the spring 30 is too strong, when the horizontal position of the lens shifts,
Due to the frictional force between the lenses 6 and 7 and the protrusions 19, 20 or 22 and 23, there is a problem in that the lenses will not return to their original positions. Similarly, if the springs 32 and 35 are too strong, the vertical position will not return. Further, even if the spring force is balanced at the time of assembly, the spring force may be out of balance due to aging or the like. Further, there is a problem that the number of parts is large and the assembling process is also large. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems of the prior art and provide an optical scanning device having a lens fixing structure which has a simple structure, is easy to assemble, and is strong against impact.

[0006]

SUMMARY OF THE INVENTION The present invention is an optical scanning device having a deflecting means for deflecting a light beam, a lens for forming an image of the light beam deflected by the deflecting means, and an optical housing. There are a plurality of the lenses, of which 2
An oblique notch is provided in at least a part of the upper ends of the surfaces of the two lenses facing each other, and a projection is provided on the optical housing outside the position where the two lenses are to be fixed. A lens pressing member that is in contact with the cutout surfaces of the two lenses at the same time, and a pressing unit that presses the lens pressing member downward are characterized by being provided.

[0007]

In the present invention, a notch is provided at the upper end of the opposing surface of the two lenses, and the lens pressing member is provided with a notch.
Since the structure in which the one lens is pushed downward at the same time, the upper part of the lens as well as the lower part of the lens is supported in the horizontal direction by friction, and the displacement due to vibration, impact, etc. is less likely to occur. Further, the pressing force in the horizontal direction is always proportional to the pressing force in the vertical direction, and even if the lens position temporarily shifts due to a strong impact or the like, the lens immediately restores to its original position. Positional deviation of the lens due to pressure imbalance does not occur. In addition, the number of parts is small and the assemblability is improved.

[0008]

FIG. 2 is a diagram showing an example of an optical system of a printer using an optical scanning device to which the present invention is applied. The optical housing 1 includes a laser light source unit 2, a mirror 4, and a polygon unit (not shown) having a polygon mirror 5, and a first f for focusing the laser light on the photosensitive drum 2.
The θ lens 6 and the second fθ lens 7 are attached. 8
Indicates the optical axis, and the photosensitive drum 2 is scanned as the polygon mirror 5 rotates.

FIG. 1 shows an optical housing with a partly cutaway fθ.
It is a front view near a lens. The optical housing 1 has a first f
Three projections 22 and 23 that define a horizontal reference plane for supporting the θ lens 6 and a horizontal positioning projection 21 of the lens 6 are provided. Similarly, projections 19, 20 and 18 are provided for supporting and positioning the second fθ lens 7. Columnar members 16 for supporting the upper bridge member 12 extend from both side surfaces of the housing 1. First
The cross sections of the fθ lens 6 and the second fθ lens 7 are substantially rectangular, and an oblique notch 9 is provided at the upper end of the facing surface of the two lenses. The angle of inclination of the notch may be such that the lens does not fall over without the screws 14 and 15. However, the closer the angle is to the horizontal, the smaller the restoring force with respect to the displacement in the horizontal direction.

A lens pressing member 10 having a shape that is in contact with both of the notched surfaces at the same time is arranged across the notched portions 9 of the two lenses.
It is pressed downward by the pressing spring 11. Both surfaces of the lens pressing member 10 and the notch surface of the lens are processed so that a certain amount of frictional force is generated. The pressing spring 11 is fixed to the bridge member 12, and applies a restoring force to the vertical displacement of the lens and also generates a frictional force between the lens pressing member 10 and the notched surface of the lens. An overhanging portion 13 extends from the bridge member 12 to the upper portions of both lenses, and screws 14 and 15 provided on the overhanging portion 13 lightly contact the respective lenses. The screws 14 and 15 are provided to prevent the lens from being largely displaced by an impact or the like.

FIG. 3 is a plan view showing a lens portion of the optical housing according to the present invention. The first fθ lens 6 is supported by the three protrusions 22 and 23 and is in contact with the positioning protrusion 21. In addition, the second fθ lens has three protrusions 19,
It is supported by 20, and abuts on the positioning projection 18. The lens pressing screws 14 and 15 are arranged so as to press substantially the centers of the three vertical positioning projections. The pressing spring 11 has a substantially H shape, and is fixed to the bridge member 12 by, for example, an adhesive, a screw, a rivet or the like. The bridge member 12 is fixed to the columnar member 16 extending from the side surface of the optical housing 1 with a screw 17. The bridge member 12
Although the overhanging portion 13 extends from the left to the right, the width of the bridge member 12 may be wider than the distance between the screws 14 and 15 over the entire width.

When assembling the optical housing, similarly to the conventional fixing method using a spring, a force is temporarily applied in the horizontal direction after the assembly to position the lens at a predetermined position.
After that, the screws 14 and 15 are lightly tightened and fixed so as not to distort the lens. In this state, when the lens tries to move in the horizontal direction due to impact, there is friction between the lens and the lens pressing member 10, so that the lens pressing member 10 is pressed in the horizontal direction by one of the lenses. 10 does not move because it is hitting the other lens. Further, since the frictional force becomes extremely large with respect to sudden acceleration such as impact, the frictional force and the pressing spring 11
It becomes difficult to push up the lens pressing member upward against the force of. On the contrary, when the vibration is small, the frictional force becomes weak, but in this case, if the lens is displaced from the original position, the lens is pushed by the lens pressing member 10 and returns to the original position. .

FIG. 5 is a diagram showing the outline of another embodiment of the present invention. FIG. 5A shows an example in which the lens pressing member 10 is pressed by the spring spring 40, and any other kind, shape and number of springs can be used. Also in FIG.
(B) is an example in which the lens pressing member 10 is pressed by an arbitrary elastic member 12 such as rubber sandwiched between the lens pressing member 10 and the bridge member 12. Figure 5
(C) is an example in which the lens pressing member 10 is directly pressed by the screw 42. In this case, the lens pressing member 1
0, the stress due to elastic deformation of the bridge member 12, etc. acts instead of the force of the spring. FIG. 5D shows an elastic member 4 such as rubber.
This is an example in which the lens is directly pressed in 3. In this case, the shape or presence of the cutout portion of the lens does not matter so much. FIG. 5E shows an example in which the lens pressing member 44 is formed of an elastic member such as a leaf spring. In this example, the lens pressing member 44 is supported by the screw 45, but if the lens pressing member 44 is formed in such a shape that the lens pressing member 44 abuts on the bridge member 12, the screw 45 will be screwed.
Can be omitted.

Although the embodiments have been described above, the present invention may be modified as follows. Lens holding member 1
The contact between 0 and the notch of the lens does not have to be a surface,
For example, it may be a line or a point. That is, the notch surface of the lens and the inclined surface of the lens pressing member 10 do not have to be flat, and one or both surfaces of the lens or the lens pressing member are spherical surfaces, cylindrical surfaces, protrusions in a mountain range having a triangular cross section, or It may be a cylindrical depression or the like. In the example, a screw 14 fixing the top of the lens,
15 is not always necessary and may be replaced by another structure, for example, a member which extends from the bridge member 12 and constitutes an abutting surface.

Even if the lens has three or more lenses,
If two lens blocks are formed by adhesion, the present invention can be applied as it is. Further, other lenses may be present before or after or in the middle of the lenses 6 and 7 of the embodiment. In the embodiment, the pressing spring 11 does not need to be fixed to the bridge member 12, and only a structure such as a fitting pin or a recess for restricting the position of the spring 11 in a plane parallel to the bridge member 12 is provided. But it's okay. The lens fixing structure of the present invention can also be applied to fix one lens, in which case, instead of the second lens,
A member having a cutout portion may be used, or the other end of the lens pressing member 10 may be rotatably supported.

[0016]

As described above, according to the present invention,
A notch is provided at the upper end of the opposing surface of the two lenses,
Since the lens pressing member has a structure in which the two lenses are simultaneously pushed downward, the lower part of the lens and the upper part of the lens are supported in the horizontal direction by friction, and the displacement due to vibration or shock is unlikely to occur. Further, the pressing force in the horizontal direction is always proportional to the pressing force in the vertical direction, and even if the lens position temporarily shifts due to a strong impact or the like, the lens immediately restores to its original position. Positional deviation of the lens due to pressure imbalance does not occur. In addition, the number of parts is small and the assemblability is improved.

[Brief description of drawings]

FIG. 1 is a front view in the vicinity of an fθ lens with a part of an optical housing cut away.

FIG. 2 is a diagram showing an example of an optical system of a printer using an optical scanning device to which the present invention is applied.

FIG. 3 is a plan view showing a lens portion of an optical housing according to the present invention.

FIG. 4 is a front view of the vicinity of an fθ lens of a conventional optical housing.

FIG. 5 is a diagram showing an outline of another embodiment of the present invention.

[Explanation of symbols]

1 ... Optical housing, 2 ... Photosensitive drum, 3 ... Laser light source section,
4 ... Mirror, 5 ... Polygon mirror, 6 ... 1st f (theta) lens, 7 ... 2nd f (theta) lens, 8 ... Optical axis, 9 ... Notch part, 10 ... Lens pressing member, 11 ... Pressing spring, 12
... Bridge member, 13 ... Overhanging portion, 14, 15 ... Screw, 16 ... Columnar member, 18, 21 ... Positioning projection

Claims (1)

[Claims] 1. An optical scanning device having a deflecting means for deflecting a light beam, a lens for forming an image of the light beam deflected by the deflecting means, and an optical housing, wherein a plurality of the lenses are present, At least a part of the upper ends of the surfaces of the two lenses facing each other is provided with an oblique notch, and a projection is provided outside the position where the two lenses are to be fixed in the optical housing. A lens pressing member that is provided and that is in contact with the cutout surfaces of the two lenses at the same time;
An optical scanning device comprising: a pressing unit that presses the lens pressing member downward.