JPH0536408U - fθ lens holding structure - Google Patents

Abstract

(57) [Summary] [Purpose] By reducing the number of parts and assembling time, cost reduction can be achieved and application device can be made compact. In a holding structure in which the fθ lenses 5 and 6 are positioned by a positioning member provided in the housing 1 and fixed by a holding means, side surfaces of the fθ lenses 5 and 6 and the fθ lens among the positioning members are included. The space portions 17 and 18 are set between the space portions 17 and 18 that are in contact with the side surface portions of the above, and the fθ lens is fixed and held by the adhesive agent filled in the space portions 17 and 18. In addition, an elastic holding portion 21 is provided on the back surface of the cover 20 that covers the housing, and f is positioned by the positioning member.
The θ lenses 5 and 6 may be pressed and held by the elastic holding portion 21. Furthermore, the specified bonding means and the pressure holding means by the elastic holding portion 21 may be used together.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an fθ lens holding structure suitable for an optical scanning device such as a laser printer or a laser fax.

[0002]

[Prior art]

 The optical scanning device deflects the light beam emitted from the light source unit by using a rotary polygon mirror, and scans the image plane through an fθ lens. The fθ lens is usually a relatively long lens due to the incidence of deflected laser light, and is positioned by a positioning member in each direction provided in the device housing, and is fixedly held by spring means such as a leaf spring. Has been done. As an example of this holding structure, Japanese Utility Model Laid-Open No. 63-80514 can be cited. Using a position regulating member and a pressing member made of elastic metal members, the restoring force due to the deformation of each elastic metal member is used. By utilizing this, the front surface, side surface, and upper surface of the fθ lens are pressed and held toward the reference surfaces of the respective position regulating members.

[0003]

[Problems to be solved by the device]

 However, in the holding structure using the leaf spring, the leaf spring is expensive, and in addition to the need for accessory parts such as spring-fastening screws, the number of parts is large, and the number of assembling steps is large, resulting in a cost reduction. This is an obstacle to reduction. Further, in a plastic fθ lens, when it is locally pressed by a leaf spring, distortion occurs and the lens characteristics are disturbed.

Therefore, the present invention provides a holding structure for an fθ lens, which can reduce the number of parts and the assembling time, thereby achieving further cost reduction and contributing to downsizing. To aim.

[0005]

In order to achieve the above-mentioned object, the present invention has a rotary polygon mirror incorporated in a housing and an fθ lens for passing a light beam deflected by the rotary polygon mirror, In the holding structure of the fθ lens in which the fθ lens is positioned by the positioning member provided in the housing and is fixed by the holding means, the side surface of the fθ lens and the side surface part of the fθ lens of the positioning member. A space portion is set between the space portion and the one that is in contact with, and the fθ lens is fixedly held by an adhesive agent filled in the space portion. Further, the holding means may be provided with an elastic holding portion that extends to the back surface of the cover that covers the housing, and the fθ lens positioned by the positioning member may be pressed and held by the elastic holding portion. Further, a space portion is set between the side surface of the fθ lens and one of the positioning members that is in contact with the side surface portion of the fθ lens, and the fθ lens is fixedly held by the adhesive filled in the space portion. On the other hand, an elastic holding portion may be provided on the back surface of the cover that covers the housing, and the elastic holding portion may press and hold the fθ lens. In this case, a reliable holding force can be obtained with a simple structure. Here, when the elastic holding portion is pressed and held, at least one of the front surface, rear surface, side surface and upper surface of the fθ lens is pressed toward the reference surface of each positioning member.

[0006]

【Example】

 1 and 2 show a first embodiment of the present invention, and FIG. 1 is an assembly view showing a housing of an optical scanning device to which the present invention is applied. The optical scanning device shown in the figure is a light source unit 2 mounted on one side of a housing 1, a polygon mirror 3 installed inside the housing and rotating at an equal angular velocity, and a polygon mirror 3 which is arranged opposite to and deflected. Equipped with fθ lenses 5 and 6 for converting the laser light at a constant speed, a photosensitive drum (not shown) installed outside the housing 1, the laser light emitted from the light source unit 2 is deflected by the polygon mirror 3, and f The photosensitive drum is made to scan with the laser light that has been subjected to constant velocity conversion by the θ lenses 5 and 6. The fθ lenses 5 and 6 are disposed inside the housing 1 with a predetermined space therebetween, and are arranged opposite to the polygon mirror 3. The holding structure of the present invention is applied to the position regulation of the fθ lens 5 and the fθ lens 6, and they are fixedly held using an elastic adhesive in a state of being positioned and arranged by each positioning member. The fθ lens 5 is positioned by the positioning member 7 or 8 provided on either side of the lens as a reference and the cylindrical positioning members 9 and 10 provided on the lens front side, and the fθ lens 6 is positioned on both sides of the lens. The position is regulated by the positioning member 11 or 12 which is provided as a reference, and the cylindrical positioning members 13 and 14 provided on the rear surface side of the lens.

FIG. 2 shows a holding structure for the fθ lens 5, and the main part of the present invention will be described below with reference to FIG. The positioning members 7 and 8 are integrally installed on the inner surface of the housing 1 and have a substantially L-shaped cross section having a height substantially equal to the lens thickness. The L-shaped vertical wall 15 is provided with a concave portion 15a at a portion in contact with the lens side surface 5a. Due to the presence of the concave portion 15a, when the side surface 5a of the fθ lens 5 abuts on the inner surface of the vertical wall 15, the side surface 5a is formed. A first space portion 17 is formed between them. Further, the L-shaped vertical wall 16 is close to the taper surface 5c formed between the side surface 5a and the rear surface 5b of the fθ lens 5, and in that state, between the taper surface 5c and the vertical wall 16. The second space portion 18 is formed in.

Therefore, the position of the fθ lens 5 is regulated in the front-rear direction and the left-right direction by the positioning members 9 and 10 and the positioning members 7 and 8 with one of them as a reference, and in this state, two spaces are formed on the side surface of the lens. The parts 17 and 18 are formed. The space portions 17 and 18 are filled with an elastic adhesive 19 as shown on the right side of the figure, and the f.theta. Lens 5 is fixedly held at both sides thereof via the elastic adhesive 19. This also applies to the fθ lens 6. At this time, the filling operation of the elastic adhesive 19 uses the positioning members 9 and 10 provided at predetermined positions in addition to the space portions 17 and 18 being located on both sides of the fθ lens 5. As a result, automation on the assembly line becomes easier than manual operation. At the same time, it is possible to design the filling amount arbitrarily, and it is difficult for the characteristics of the lens to be affected by variations in the filling amount. Moreover, since the elastic adhesive 19 contacts both side surfaces 5a and the taper 5b of the f.theta. Lens 5 which is a rough surface, the contact area is increased and the adhesive effect is improved. It should be noted that the adhesive 19 does not necessarily have to be filled in both the space portions 17 and 18, but may be filled in only one of the space portions 17 and 18 depending on the size of the fθ lens 5 and the area of the side surface portion. It is also possible to satisfy the designed adhesive holding force.

3 and 4 show the essential parts of the second embodiment. The housing 1 is covered with a cover 20 made of synthetic resin, and the cover 20 has an elastic base portion 21 that slightly projects to the back side and elastic holding pieces 22 and 23 protruding from the elastic base 21. The elastic base portion 21 and the elastic holding pieces 22 and 23 serving as the elastic holding portions are such that the top surface, rear surface, and side surfaces of the f θ lens 5 face the reference surfaces of the respective positioning members with the cover 20 mounted on the housing 1. The cover 20 is pressed and fixed, and is integrally molded with the cover 20 by two-color molding or the like, and is relatively flexible and rich in elasticity. The positions of the elastic base portion 21 and the elastic holding pieces 22 and 23 and the amount of overhanging are the reference values of the positioning members such as the upper surface, the side surface, and the rear surface near the side portion 5a of the fθ lens 5 when the cover 20 is mounted on the housing 1. It is set so that it comes into contact with the surface with an appropriate pressing force. Therefore, the position of the fθ lens 5 is regulated in the front-rear direction and the left-right direction by the positioning members 9 and 10 and the positioning member 7 or 8 with one of them serving as a reference, as in the above-described embodiment. After that, by attaching the cover 20 to the housing 1, the elastic base portion 21 and the elastic holding pieces 22 and 23 press from the upper surface, the side surface, and the rear surface of the lens, respectively, and as a result, the fθ lens 5 is fixed and held with appropriate elasticity. It is.

It has been confirmed that this holding means can secure the designed holding force in the case of a relatively small fθ lens. If the fθ lens becomes large, the holding force tends to be insufficient. In such a case, as in the first embodiment, one of the space portions 17 and 18 on the side surface of the lens is filled with the adhesive 19 to make the fθ lens. It is preferable to fix them with a certain holding force. By using the fixing and holding by the adhesive material 19 and the pressing and holding by the elastic base portion 21 and the elastic holding pieces 22 and 23 together, the reliability with respect to the holding force can be improved, and the number of parts and the number of assembling steps can be greatly reduced.

[0011]

[Effect of the device]

 As described above, the holding structure of the fθ lens according to the present invention can reduce the number of parts and the assembling time as compared with the conventional one using the leaf spring, and can also make the applied device compact. Can contribute. In addition, by setting a space for filling the adhesive between the side surface of the fθ lens and the positioning member that is in contact with the side surface of the fθ lens, an excellent adhesive effect can be expected, and automation is also possible. It will be easy. Further, by utilizing the elastic holding portion provided on the back surface of the cover that covers the housing, it is possible to further reduce the number of parts and the assembly time. In this case, the holding force can be surely satisfied by using the adhesive together with the space.

[Brief description of drawings]

FIG. 1 is an assembly view showing a housing of an optical scanning device to which the present invention is applied.

FIG. 2 is a main part perspective view showing a holding structure of an fθ lens provided in the housing.

FIG. 3 is a main part perspective view showing another example of the holding structure.

FIG. 4 is a cross-sectional view of an essential part showing details of the holding structure.

[Explanation of symbols]

 1 Housing 2 Light Source Unit 3 Polygon Mirror (Rotating Polygonal Mirror) 7, 8, 9, 10 Positioning Member 11, 12, 13, 14 Positioning Member 17, 18 Space 19 Adhesive 20 Cover for Cover 21 Elastic Base (Elastic) Holding part) 22,23 Elastic holding piece (elastic holding part)

Claims (3)

[Scope of utility model registration request] 1. A rotary polygon mirror incorporated in a housing, and f for passing a light beam deflected by the rotary polygon mirror.
a lens and the fθ lens is positioned by a positioning member provided in the housing,
In the holding structure for the fθ lens fixed by the holding means, a space is set between the side surface of the fθ lens and one of the positioning members that is in contact with the side surface of the fθ lens, and the space is filled. A holding structure for an fθ lens, wherein the fθ lens is fixedly held by an adhesive. 2. A rotary polygon mirror incorporated in a housing, and f for passing a light beam deflected by the rotary polygon mirror.
a lens and the fθ lens is positioned by a positioning member provided in the housing,
In the holding structure of the fθ lens fixed by the holding means, the holding means is provided with an elastic holding portion that projects on the back surface of the cover that covers the housing, and the fθ lens positioned by the positioning member is held by the elastic holding portion. A holding structure for an fθ lens, which is characterized by being pressed and held. 3. A rotary polygon mirror incorporated in a housing, and f for passing a light beam deflected by the rotary polygon mirror.
a lens and the fθ lens is positioned by a positioning member provided in the housing,
In the holding structure of the fθ lens fixed by the holding means, in the side surface of the fθ lens and the positioning member, f
A space is formed between the θ lens and the side surface of the θ lens that is in contact with the side surface, and the fθ lens is fixed and held by an adhesive filled in the space, while the fθ lens is extended to the back surface of the cover that covers the housing. An elastic holding portion is provided, and the elastic holding portion presses and holds the fθ lens.
Lens holding structure.