JP2007127793A - Laser scanning optical apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a laser scanning optical apparatus in which the distortion of a long optical element due to the variation in temperature or the like is resolved with a simple structure. <P>SOLUTION: In the laser scanning optical apparatus, a long lens 7 is adhered and fixed on a housing 20 on which a slit 21 for passing light is formed. Protrusions 22 stretching in the longitudinal direction Y of the lens 7 are formed on the housing 20 corresponding to the adhered and fixed parts of both end parts of the lens 7. When the lens 7 is deformed due to a temperature rise, the adhesive is deformed in the longitudinal direction Y without being regulated by the protrusions 22 and the strain of the lens 7 is resolved. The protrusions 22 regulate the deformation of the adhesive in the Z-direction transverse to the Y-direction, and the lens 7 is not deformed in the Z-direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laser scanning optical apparatus, and more particularly to a laser scanning optical apparatus for forming an electrostatic latent image on a photosensitive member incorporated in an image forming apparatus such as an electrophotographic copying machine or printer.

  Conventionally, in an image forming apparatus such as a copying machine or a printer, a laser scanning optical device for forming an electrostatic latent image on a photosensitive member has a long optical element such as a lens. The position was fixed with high accuracy. In order to reduce the size and cost of laser scanning optical devices, it is common practice to bond and fix these optical elements to a housing.

  By the way, as shown in FIG. 18A, when the long optical element 55 is firmly bonded and fixed to the housing 50 by the adhesive 56 at both ends, the linear expansion integer of the optical element 55 is larger than that of the housing 50. Since it is large, as shown in FIG. 18B, the optical element 55 is stretched more than the housing 50 due to an increase in the in-machine temperature, the optical element 55 is distorted in a mountain shape, and the optical performance is adversely affected.

  Therefore, conventionally, as shown in FIG. 19A, the optical element 55 is elastically pressed and fixed onto the rib 51 formed on the housing 50 by the spring member 57, and the distortion of the optical element 55 caused by a temperature rise or the like. The optical element 55 has a structure that allows the optical element 55 to slide between the housing 50 and the spring member 57 (see FIG. 19B).

  Further, Patent Document 1 describes that the elasticity of an adhesive is used to absorb a difference in linear expansion coefficient by deformation of the adhesive to eliminate distortion of the optical element. Patent Document 2 describes that a hole is provided so as to surround the optical element fixing portion of the housing, and the distortion of the optical element is eliminated by making the housing elastic.

  However, in the structure using the spring member 57 shown in FIG. 19, the number of parts is increased, the cost is increased, and the distortion of the optical element 55 can be released in the arrow Y direction, but is released in the Z direction orthogonal thereto. May not be able to be controlled, and there is a risk of drawing line skew and the like.

  Further, as described in Patent Document 1 (see FIG. 20A), even in a structure in which the distortion of the optical element 55 is eliminated by the deformation of the adhesive 56, as shown in FIG. Can be escaped in the arrow Y direction, but it cannot be controlled to escape in the Z direction perpendicular to the arrow Y, and there is a possibility that a skew or the like may occur in the drawing line.

The displacement of the optical element in the arrow Z direction can be restricted by providing a guide member on the housing. However, the displacement amount of the optical element is on the order of several tens of μm, and it is difficult to accurately control such a minute displacement amount with the guide member.
JP-A-11-64715 Japanese Patent Laid-Open No. 2002-11697

  SUMMARY OF THE INVENTION An object of the present invention is to provide a laser scanning optical device that can eliminate distortion of a long optical element due to a temperature change or the like with a simple configuration.

  In order to achieve the above object, according to a first aspect of the present invention, in a laser scanning optical apparatus in which a long optical element is bonded and fixed to a housing, the optical element or an adhesive fixing portion of the housing extends in the longitudinal direction of the optical element. It is characterized in that an existing convex portion is provided.

  According to a second aspect of the present invention, in the laser scanning optical apparatus in which a long optical element is bonded and fixed to a housing, a concave portion extending in the longitudinal direction of the optical element is provided in the optical element or an adhesive fixing portion of the housing. Features.

  According to a third aspect of the present invention, in the laser scanning optical apparatus in which the long optical element is bonded and fixed to the housing, the optical element and the adhesive fixing portion of the housing are each provided with a convex portion extending in the longitudinal direction of the optical element, The respective convex portions are not in contact with each other.

  According to a fourth aspect of the present invention, in the laser scanning optical apparatus in which the long optical element is bonded and fixed to the housing, the optical element and the bonding fixed portion of the housing respectively extend in the longitudinal direction of the optical element and face each other. Protruding portions and recessed portions are provided.

  The present invention has a simple configuration in which concave portions and / or convex portions are formed in the optical element and / or the housing. When the concave and / or convex portions are formed in the adhesive fixing portion between the optical element and the housing, the extension in the shearing direction due to the internal stress of the adhesive caused by the distortion of the optical element is controlled by the concave and / or convex portions. can do. That is, since the concave portion and / or the convex portion extend in the longitudinal direction (Y direction) of the optical element, the adhesive is deformed by the shearing force in the longitudinal direction (Y direction) to eliminate the distortion. On the other hand, the adhesive is in a state of compressive deformation at the concave portion and / or the convex portion with respect to the shearing force in the Z direction perpendicular to the longitudinal direction. Does not deform. That is, the optical element is hardly displaced in the Z direction perpendicular to the longitudinal direction, and there is no possibility that a skew or the like occurs in the drawing line.

  In the present invention, the adhesive cannot exert a sufficient effect unless it is applied so as to come into contact with and cover the concave portions and / or convex portions.

  Embodiments of a laser scanning optical apparatus according to the present invention will be described below with reference to the accompanying drawings. In addition, in the 1st-6th Example shown below, the same code | symbol is attached | subjected to the same member and the overlapping description is abbreviate | omitted.

(Schematic configuration of laser scanning optical device, see FIG. 1)
FIG. 1 shows a schematic configuration of a laser scanning optical apparatus according to the present invention. The laser scanning optical device 1 condenses a laser beam emitted from a laser diode 2 on a reflecting surface of a polygon mirror 4 by a first optical system 3 including a collimator lens and a cylinder lens, and based on the rotation of the polygon mirror 4. The laser beam is deflected at a constant angular velocity in the main scanning direction Y, and then imaged / scanned by the second optical system 5 including the lenses 6 and 7 having an aberration correction function, and in the arrow direction A through the dust-proof glass 8. The photosensitive drum 10 that is driven to rotate is exposed in the main scanning direction Y.

  The configuration and operation of each optical element of this type of laser scanning optical apparatus 1 used for forming an image by electrophotography are well known and will not be described in detail.

(Refer to the first embodiment, FIG. 2 and FIG. 3)
In the first embodiment, as shown in FIGS. 2 and 3, the housing 20 is made of a highly rigid resin, and the long lens 7 is made of an optical resin. A slit 21 for transmitting a beam is formed in the housing 20, and convex portions 22 are formed along the longitudinal direction Y of the lens 7 at positions adjacent to both ends of the slit 21. The lens 7 is bonded and fixed on the housing 20 at both ends by an adhesive 30 applied to the convex portion 22 including its periphery.

In the above configuration, the temperature of the laser scanning optical device 1 increases with the heat generation of the drive motor (not shown) of the polygon mirror 4 and the internal temperature of the printer, depending on the operating state of the printer. The linear expansion coefficient of the housing 20 is approximately 3 × 10 ⁻⁵ , and the linear expansion coefficient of the lens 7 is 6 to 9 × 10 ⁻⁵ , and the lens 7 tends to expand more than the housing 20, and the lens 7 with respect to the adhesive 30. The shear deformation force in the longitudinal direction Y and the Z direction perpendicular thereto is applied.

  However, in the first embodiment, the convex portion 22 is formed in the adhesive fixing portion between the lens 7 and the housing 20, and the convex portion 22 extends in the longitudinal direction Y of the lens 7. No. 30 is deformed with respect to the shearing force in the longitudinal direction (Y direction) to eliminate the distortion of the lens 7. As a result, the optical performance of the lens 7 does not deteriorate. On the other hand, the adhesive 30 is compressed and deformed by the convex portion 22 with respect to the shearing force in the Z direction orthogonal to the longitudinal direction Y. To deform the adhesive 30, a force much larger than the shearing deformation force is required. Does not deform. That is, the lens 7 is hardly displaced in the Z direction, and there is no possibility that a skew or the like occurs in the drawing line. Even if the convex portions 22 are formed on the lower surface sides of the both end portions of the lens 7, the same effect can be obtained. This also applies to the following modified examples and examples.

(Modification of the first embodiment, see FIGS. 4 to 6)
In Modification 1 shown in FIG. 4, two convex portions 22 are formed on the housing 20. The operational effects of the first embodiment are further improved. In Modification 2 shown in FIG. 5, a plurality of thin convex portions 22 are formed on the housing 20. A narrow concave portion is formed between the convex portions 22, and the concave and convex portions prevent displacement of the lens 7 in the Z direction. This modification 2 is effective when the dimension in the longitudinal direction Y of the adhesive fixing portion of the lens 7 is short. In Modification 3 shown in FIG. 6, the cross section of the convex portion 22 provided on the housing 20 is triangular. In addition, the cross section of the convex part 22 may be various shapes such as a trapezoid in addition to a rectangle and a triangle.

(Refer to the second embodiment, FIG. 7)
In the second embodiment, as shown in FIG. 7, in addition to the configuration of the first embodiment, the housing 20 is provided with a projecting piece 25 facing the central portion in the longitudinal direction Y of the lens 7. The lens 7 is bonded and fixed to the central side surface with an adhesive. A convex portion 26 extending in the longitudinal direction Y is formed on the projecting piece 25, and the central portion of the lens 7 is bonded and fixed to the projecting piece 25 with the adhesive covering the convex portion 26. Since the convex part 26 extends in the longitudinal direction Y, the central part of the lens 7 can be restricted from being displaced in the Z direction and the X direction. Further, by providing the same projecting piece on the part facing the projecting piece 25 and the slit 21 and bonding and fixing both side surfaces of the lens 7, the displacement in the Z direction and the Y direction can be more effectively regulated. Can do.

(Refer to the third embodiment, FIGS. 8 and 9)
In the third embodiment, as shown in FIGS. 8 and 9, a convex portion 22 is formed in the housing 20 in the same manner as the first embodiment, and the convex portion extending in the longitudinal direction (Y direction) of the lens 7 is formed. 7a, 7a was formed. The convex portion 22 and the convex portions 7a and 7a are formed in a state where the positions thereof are shifted from each other in the Z direction, and do not face each other, and the convex portion 22 faces the concave portion 7b between the convex portions 7a and 7a. The adhesive 30 is filled from between the convex portion 22 and the concave portion 7b to the outside of the convex portions 7a and 7a, and the lens 7 is adhered and fixed on the housing 20 at both ends.

  Also in the third embodiment, since the convex portions 22, 7 a, 7 a formed on the adhesive fixing portion between the lens 7 and the housing 20 extend in the longitudinal direction Y of the lens 7, the adhesive 30 is in the longitudinal direction. Deforms the shearing force in the (Y direction) to eliminate the distortion of the lens 7. As a result, the optical performance of the lens 7 does not deteriorate. On the other hand, the adhesive is compressed and deformed by the convex portions 22, 7a and 7a with respect to the shearing force in the Z direction perpendicular to the longitudinal direction Y, and a larger shearing deformation force than that in the first embodiment is required for the deformation. And is not easily deformed. That is, the lens 7 is hardly displaced in the Z direction, and there is no possibility that a skew or the like occurs in the drawing line.

(Refer to the fourth embodiment, FIGS. 10 and 11)
In the fourth embodiment, as shown in FIGS. 10 and 11, a convex portion 22 is formed on the housing 20 in the same manner as the first to third embodiments, and the lens 7 extends in the longitudinal direction (Y direction). A slightly wide recess 7c was formed. The adhesive 30 is filled from between the convex portion 22 and the concave portion 7c to the outside of the concave portion 7c, and the lens 7 is bonded and fixed on the housing 20 at both ends.

  Also in the fourth embodiment, since the convex portion 22 and the concave portion 7c formed in the adhesive fixing portion between the lens 7 and the housing 20 extend in the longitudinal direction Y of the lens 7, the adhesive 30 is in the longitudinal direction ( The lens 7 is deformed to eliminate the distortion of the lens 7 with respect to the shearing force in the Y direction). As a result, the optical performance of the lens 7 does not deteriorate. On the other hand, the adhesive is compressed and deformed by the convex portion 22 and the concave portion 7c with respect to the shearing force in the Z direction perpendicular to the longitudinal direction Y, and a larger shear deformation force than that of the first embodiment is required for the deformation. Does not easily deform. That is, the lens 7 is hardly displaced in the Z direction, and there is no possibility that a skew or the like occurs in the drawing line.

(Refer to the fifth embodiment, FIG. 12)
In the fifth embodiment, as shown in FIG. 12, the housing 20 is formed with a convex portion 22 similar to the first embodiment adjacent to one end of the slit 21 and adjacent to the other end of the slit 21. Protrusions 23, 24, and 24 extending in the Y direction and the Z direction were formed. That is, since the deformation of the adhesive is restricted in the Y direction and the Z direction at the convex portions 23, 24, 24 at the other end, the position of the lens 7 is fixed at the other end, and the adhesive is applied at the convex portion 22 at the one end. By deforming in the Y direction, distortion of the lens 7 due to temperature rise is eliminated.

  The lens 7 is fixed at the other end in this manner by forming Y (yellow), M (magenta), C (cyan), and K (black) images on the four photosensitive drums arranged side by side. This is because the laser scanning optical device corresponding to a so-called tandem type image forming apparatus in which these images are primarily transferred and synthesized on the intermediate transfer member and then secondarily transferred onto the recording paper. In such a laser scanning optical device, four lenses 7 are arranged in parallel in the housing, but not only the optical performance of each lens 7 is ensured but also the relative optical performance of each lens 7 is improved. It is necessary to suppress the deviation. Therefore, in the laser scanning optical apparatus corresponding to the tandem type, the relative deviation of the optical performance is reduced with the other end of each lens 7 as a reference.

(Refer to the modified example of the fifth embodiment, FIG. 13 and FIG. 14)
In the modification shown in FIG. 13, a plurality of circular convex portions 31 are formed adjacent to the other end of the slit 21. A convex portion 22 is formed at a position adjacent to one end of the slit 21. Also in this modification, the displacement in the Y direction and the Z direction can be restricted at the other end of the lens 7 as in the fifth embodiment. This modification is effective when the end of the lens 7 is narrow in the Z direction.

  Note that in order to reduce the relative shift in optical performance by fixing the other end of the lens 7, the convex portions 32 to 34 having various shapes shown in FIGS. 14A to 14C may be formed. Good. Further, as shown in FIG. 14D, a convex portion 7d or the like that can restrict displacement in the Y direction and the Z direction may be formed on the back surface of the other end of the lens 7.

(See the sixth embodiment, FIG. 15)
As in the fifth embodiment, the sixth embodiment is a tandem type laser scanning optical apparatus, and as shown in FIG. 15, the central portion in the longitudinal direction of the lens 7 is used as a reference position that is not displaced in the Y direction. It is a function. That is, both end portions of the lens 7 can be displaced in the Y direction by the convex portion 22 and are restricted from being displaced in the Z direction. Further, the housing 20 is provided with a projecting piece 27 facing the central portion of the lens 7 in the longitudinal direction Y, and the projecting piece 27 and the side surface of the central portion of the lens 7 are bonded and fixed with an adhesive. A convex part 28 extending in the vertical direction X is formed on the projecting piece 27, and the central part of the lens 7 is bonded and fixed to the projecting piece 27 with the adhesive covering the convex part 28. Since the convex portion 28 extends in the vertical direction X, displacement of the central portion of the lens 7 in the Y direction and the Z direction is restricted. Furthermore, the function as a reference position can be improved by providing the same protrusion piece in the part which opposes the protrusion piece 27 and the slit 21 and bonding and fixing both side surfaces of the lens 7.

(Refer to the seventh embodiment, FIG. 16)
In the seventh embodiment, as shown in FIG. 16, a pair of projecting pieces 35, 35 are provided on the housing 20, and a long lens 7 is bonded and fixed on the projecting pieces 35, 35. In this case, the point which provided the convex part 22 extended in the longitudinal direction Y of the lens 7 on the protrusions 35 and 35 is the same as that of the said 1st Example. Of course, the protrusions 35 and 35 and the lens 7 may be provided with convex portions and concave portions similar to those in the second to fifth embodiments.

(Refer to the eighth embodiment, FIG. 17)
In the eighth embodiment, as shown in FIG. 17, in addition to the configuration of the seventh embodiment, a convex portion 29 is provided on the housing 20 so as to face the side surface of the central portion in the longitudinal direction Y of the lens 7. 29 is covered and fixed in a state of covering 29. The convex portion 29 extends in the Y direction, and restricts the central portion of the lens 7 from being displaced in the X direction. If the convex portion 29 is provided so as to extend in the X direction, the central portion of the lens 7 is restricted from being displaced in the Y direction, and the lens 7 is based on the central portion as in the sixth embodiment. Can be displaced.

(Other examples)
The laser scanning optical device according to the present invention is not limited to the above-described embodiments, and can be variously modified within the scope of the gist thereof.

  For example, a lens or a housing formed with a recess extending in the longitudinal direction of the lens may be used. Further, in the above-described embodiment, the one that eliminates the distortion of the long lens bonded and fixed to the housing is shown, but the distortion of the long folding mirror other than the lens may be eliminated.

  Furthermore, the materials of the housing and the lens shown in the above embodiments are merely examples, and it is needless to say that various materials can be used. As the housing, materials having different linear expansion coefficients such as a metal material such as aluminum can be used. The linear expansion coefficient of optical elements such as lenses and mirrors may be smaller than the linear expansion coefficient of the housing. Further, a long optical element such as a lens may be attached to the housing body via a holder. In this case, the optical member is bonded and fixed to the holder.

  In the present invention, various shapes can be adopted for the convex portions and the concave portions. The point is that the adhesive may be deformed with respect to the shearing force in the longitudinal direction of the optical element to eliminate the distortion of the optical element, and may be any shape that does not easily deform in the direction orthogonal to the longitudinal direction.

It is a schematic block diagram which shows an example of the laser scanning optical apparatus which concerns on this invention. It is a disassembled perspective view which shows the principal part of 1st Example. It is BB sectional drawing of FIG. It is a disassembled perspective view which shows the modification 1 of 1st Example. It is a disassembled perspective view which shows the modification 2 of 1st Example. It is a disassembled perspective view which shows the modification 3 of 1st Example. It is a disassembled perspective view which shows the principal part of 2nd Example. It is a disassembled perspective view which shows the principal part of 3rd Example. It is CC sectional drawing of FIG. It is a disassembled perspective view which shows the principal part of 4th Example. It is DD sectional drawing of FIG. It is a disassembled perspective view which shows the principal part of 5th Example. It is a disassembled perspective view which shows the modification of 5th Example. It is a perspective view which shows the various shapes of the convex part in 5th Example. It is a disassembled perspective view which shows the principal part of 6th Example. It is a disassembled perspective view which shows the principal part of 7th Example. It is a disassembled perspective view which shows the principal part of 8th Example. It is explanatory drawing which shows the fixing structure of the optical element by the conventional adhesive agent. It is explanatory drawing which shows the fixing structure of the optical element by the conventional spring member. It is explanatory drawing which shows the distortion prevention structure of the optical element by the deformation | transformation of the conventional adhesive agent.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laser scanning optical apparatus 7 ... Long lens 7a ... Convex part 7b, 7c ... Concave part 20 ... Housing 21 ... Slit 22-24, 31-34 ... Convex part 30 ... Adhesive

Claims (4)

  A laser scanning optical apparatus in which a long optical element is bonded and fixed to a housing, wherein the optical element or an adhesive fixing portion of the housing is provided with a convex portion extending in the longitudinal direction of the optical element. Optical device.   A laser scanning optical apparatus in which a long optical element is bonded and fixed to a housing, wherein the optical element or an adhesive fixing portion of the housing is provided with a recess extending in the longitudinal direction of the optical element. apparatus.   In the laser scanning optical apparatus in which a long optical element is bonded and fixed to a housing, a convex portion extending in the longitudinal direction of the optical element is provided on each of the optical element and the adhesive fixing portion of the housing. A laser scanning optical device characterized by not being opposed to each other. In the laser scanning optical apparatus in which a long optical element is bonded and fixed to a housing, a convex portion and a concave portion that extend in the longitudinal direction of the optical element and are opposed to each other are bonded to the optical element and the adhesive fixing portion of the housing, respectively. A laser scanning optical device provided.

Images