JP2009198679A - Fixing structure and fixing method for optical element, laser beam scanner, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing structure and a fixing method for an optical element which can surely cure columnar resins for adhering fixation, and also includes stable characteristics, to provide a laser beam scanner, and to provide an image forming apparatus. <P>SOLUTION: The laser beam scanner includes: a laser diode 20; a collimator lens 21 for shaping a beam radiated from the laser diode 20; a holder 26 for holding the laser diode 20; and a base material 30 fixed with the holder 26 and the collimator 21. The holder 26 is inserted to the optical axis direction in a projecting piece 31 provided at the base material 30, photocuring type columnar resins 35 are arranged at gaps T, T', and the columnar resin 35 arranged at either gap T and the columnar resin 35 arranged at the other gap T' are cured with time shifted. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fixing structure of an optical element, in particular, a fixing structure and fixing method of a light shaping element such as a laser diode and a beam shaping element such as a collimator lens, a laser beam scanning apparatus including the fixing structure, and the laser beam scanning. The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile equipped with the apparatus.

  In a laser beam scanning apparatus mounted on an image forming apparatus such as a copying machine, a printer, or a facsimile, the light source unit includes a light emitting element (laser diode) and an optical element such as a collimator lens.

  As a structure for positioning and fixing this type of optical element, the techniques described in Patent Documents 1 and 2 are known. In Patent Documents 1 and 2, an intermediate holder is provided between a heat sink with a laser diode attached and a lens holder with a lens attached, and the heat sink and the intermediate holder, and the intermediate holder and the lens holder are respectively positioned and bonded and fixed. The structure is described.

  However, in the fixing structures described in Patent Documents 1 and 2, since the intermediate holder is provided between the heat dissipation plate to which the laser diode is attached and the lens holder, the number of parts increases, and the heat dissipation plate becomes an intermediate holder. There is a problem that the heat dissipation effect is not sufficient because of being closely fixed. In particular, as the adhesive, it is preferable to use a photo-curing adhesive that can be cured accurately and quickly. However, in these fixed structures, the irradiation light does not reach the bonded part, so it is not possible to use a photo-curing adhesive, or complete curing cannot be expected. It has a problem that the accuracy cannot be ensured.

  In addition, it is necessary to consider the shrinkage or curing over time when curing after adjusting the position as a problem when using a photo-curing type resin for adhesive fixation. If a gap that can secure the irradiation path of light is formed without bringing the two surfaces to be bonded into close contact, the resin is provided in a columnar shape and contracts in the height direction. When the optical system has optical sensitivity in the shrinking direction, the adjustment state before curing cannot be maintained, and it becomes difficult to use the optical system. Furthermore, although the amount of expansion and contraction is small due to changes in temperature and humidity during use as an optical system, optical performance is deteriorated.

As shown in FIG. 14, when the holder 26 to which the laser diode 20 is fixed is bonded and fixed to the base material 30 to which the collimator lens 21 is fixed with a columnar resin 35, the beam transmitted through the collimator lens 21 is parallel when the adjustment is completed. Even if it is shaped into the light a, when the columnar resin 35 contracts in the optical axis direction X during curing, the laser diode 20 moves in the optical axis direction X. Thereby, the parallel light a becomes divergent light b.
Japanese Patent Laid-Open No. 5-136852 Japanese Patent Application Laid-Open No. 5-273383

  Accordingly, an object of the present invention is to provide an optical element fixing structure and fixing method, a laser beam scanning apparatus, and an image forming apparatus capable of reliably curing a columnar resin for adhesive fixing and having stable characteristics. There is to do.

In order to achieve the above object, an optical element fixing structure according to an aspect of the present invention includes:
In a fixing structure of an optical element in which a holder for holding at least one light emitting element and a base material to which the holder is attached are fastened with a photo-curable columnar resin, one of the holder and the base material is lighted by the other. A photo-curable columnar resin is disposed in a gap located in the front and rear of the optical axis direction formed by the pinching, and the columnar resin arranged in one gap and the other gap. The columnar resin disposed in is characterized in that it is cured with a time lag.

  In the fixing structure of the optical element, the columnar resin is adjusted in three axial directions (alignment and optical axis direction) with the columnar resin having appropriate elasticity, and then disposed in one gap. And the columnar resin disposed in the other gap are cured with a time lag. The displacement in one direction due to the shrinkage of the resin cured earlier in time is canceled by the displacement in the other direction due to the shrinkage of the resin cured later. In other words, the curing shrinkage of the columnar resin acts substantially equally on the plus side and the minus side in the optical axis direction, and as a result, the optical element is prevented from changing its position in the optical axis direction.

  An optical element fixing method according to another aspect of the present invention is an optical element fixing method in which a holder for holding at least one optical element and a base material for mounting the holder are fastened with a photo-curable columnar resin. A step of placing either one of the holder and the base material so as to be sandwiched in the optical axis direction on the other side, and a photo-curing type in an uncured state in a gap located in the front and rear of the optical axis direction formed by the sandwiching Arranging the columnar resin; adjusting the position of the optical element; and curing the columnar resin arranged in one gap and the columnar resin arranged in the other gap over time. It is characterized by having.

  A laser beam scanning apparatus according to still another embodiment of the present invention is characterized by including the optical element fixing structure. According to still another aspect of the present invention, an image forming apparatus includes the laser beam scanning device.

  Embodiments of an optical element fixing structure and fixing method, a laser beam scanning apparatus, and an image forming apparatus according to the present invention will be described below with reference to the accompanying drawings.

(See the overall configuration, Fig. 1 and Fig. 2)
1 and 2 show an embodiment of a laser beam scanning apparatus and an image forming apparatus according to the present invention. The laser beam scanning device 1 is roughly composed of a light source unit 2, a polygon mirror 3, scanning lenses 4a and 4b, a cover glass 5, and a housing 10 for holding these members. It is mounted on the forming apparatus 100.

  The image forming apparatus 100 is a so-called four-cycle color printer. Around the photosensitive drum 50, a charger 102, a laser beam scanning device 1, a rotary developing device 103 containing four colors of toner of YMCK, A known belt is provided with an intermediate transfer belt 104 and the like. A YMCK electrostatic latent image is sequentially formed on the photosensitive drum 50 by the laser beam scanning device 1, and the electrostatic latent image is developed into a predetermined color by the developing unit 103 and sequentially transferred onto the intermediate transfer belt 104. Are synthesized. The synthesized toner image is secondarily transferred onto a sheet fed from the sheet feeding unit 105 one by one by an electric field applied from the secondary transfer roller 106. Subsequently, the sheet is heated and fixed on the toner image by the fixing unit 107, and is discharged to the upper surface of the printer main body.

  The beam emitted from the light source unit 2 is shaped into light substantially parallel to the main scanning direction Y and enters the polygon mirror 3. The beam incident on the polygon mirror 3 is deflected at an equal angular velocity in the main scanning direction Y, and is corrected for aberrations by passing through the scanning lenses 4a and 4b. Then, the beam passes through the cover glass 5 and forms an image on the photosensitive drum 50. . The photosensitive drum 50 is rotationally driven at a predetermined speed, and a two-dimensional image (electrostatic latent image) is formed by the main scanning by the beam and the sub scanning by the rotation of the drum 50.

(Adjustment of light source unit, see FIGS. 3 and 4)
Here, adjustment of the light source unit 2 will be described. As shown in FIG. 3, the light source unit 2 is generally composed of a laser diode 20, a collimator lens 21 held by a lens holder 25, and a cylindrical lens 22. These elements are conventionally known.

  Here, adjustment when the collimator lens 21 and the cylindrical lens 22 are individually attached will be described with reference to FIG. This adjustment itself is a conventional method.

  First, an alignment operation for aligning the center of the laser diode 20 and the optical axis of the collimator lens 21 is performed. This is an adjustment in the sub-scanning direction Z and the main scanning direction Y, and shows a state in which the collimator lens 21 is moved from the dotted line to the solid line in FIG. Further, the distance between the laser diode 20 and the collimator lens 21 is adjusted so that the beam from the collimator lens 21 becomes parallel light along the optical axis direction X in the main scanning direction Y and the sub-scanning direction Z. Since it is parallel light, the beam state hardly changes in the optical axis direction X from the collimator lens 21. For this reason, the adjustment up to this point is not affected by the cylindrical lens 22 and the like at the subsequent stage.

  In such a parallel light generation unit, the position of the collimator lens 21 is usually adjusted with reference to the position of the laser diode 20, so that the position adjustment of the laser diode 20 is unnecessary, and conventionally, at least with respect to the laser diode 20. Adjustment with a degree of freedom in the optical axis direction X is not performed.

  On the other hand, as shown in FIG. 4B, the position adjustment of the cylindrical lens 22 is performed at a position away from the reflecting surface of the polygon mirror 3 by a predetermined distance so that there is no tilt or misalignment with mechanical accuracy. . The cylindrical lens 22 has no optical power in the main scanning direction Y, and the optical power in the sub-scanning direction Z is less sensitive to deviation in the optical axis direction X than the collimator lens 21, so that the mechanical accuracy is also low. Can be placed enough. This adjustment is also made without being influenced by the collimator lens 21.

  Thereafter, the axis of the collimator lens 21 adjusted earlier and the axis of the cylindrical lens 22 are aligned to complete the adjustment of the condensing portion. At this time, since the accuracy of the distance between the collimator lens 21 and the cylindrical lens 22 is not required, the adjustment of the optical axis direction X of the collimator lens 21 is basically unnecessary.

  By the way, in this embodiment, either the collimator lens 21 alone is used as the condensing optical element, or the collimator lens 21 and the cylindrical lens 22 are fixed to a single lens holder 25. Also good. Alternatively, a DOE (Diffractive Optical Element) having both a collimator lens function and a cylindrical lens function may be used.

  Hereinafter, various examples of fixing structures and fixing methods of the laser diode 20 and the collimator lens 21 in the light source unit 2 will be described. In addition, in each figure which shows each Example, the same code | symbol is attached | subjected to the same member and part, and the overlapping description is abbreviate | omitted.

(Refer 1st Example and FIGS. 5-7)
As shown in FIGS. 5 and 6, the light source unit 2 according to the first embodiment includes a holder 26 (heat radiating plate) for holding the laser diode 20, a base material 30 for attaching the holder 26, and the base material 30. The collimator lens 21 is bonded and fixed. The beam emitted from the laser diode 20 is shaped into parallel light by the collimator lens 21 and is condensed in the sub-scanning direction Z by a cylindrical lens (not shown).

  The holder 26 is made of, for example, stainless steel and has a flat plate shape with the flange portion of the laser diode 20 extended (see FIG. 7). The laser diode 20 is fixed to the holder 26 by being press-fitted into a hole (not shown) formed in the holder 26. The base material 30 is a resin molded product, and includes two pairs of projecting pieces 31 arranged so as to sandwich the holder 26 between both main surfaces thereof, and a projecting piece 32 for holding the collimator lens 21.

  In the gaps T and T ′ between both main surfaces of the holder 26 and the projecting piece 31, resin 35 formed in a columnar shape is arranged at eight positions on the left and right and up and down. The columnar resin 35 is, for example, an ultraviolet curable photocurable adhesive. When the columnar resin 35 applied at a predetermined position is in an uncured normal temperature state (25 ° C.), the laser diode 20 is adjusted with respect to the collimator lens 21 fixed to the base material 30 in advance by using the tension of the resin material. After adjusting the position of the core and the optical axis direction in three axial directions (main scanning direction Y, sub-scanning direction Z, and optical axis direction X), the columnar resin 35 is cured by irradiating ultraviolet rays. Thus, the light source unit 2 is manufactured with high accuracy. Thereafter, the light source unit 2 is fixed after adjusting the position of the base material 30 to the housing 10.

  More specifically, both main surfaces of the holder 26 and the projecting pieces 31 of the base material 30 face each other in a direction perpendicular to the optical axis direction X, and the columnar resin 35 is interposed in the gaps T and T ′ in an uncured state. The beam shaping state is adjusted by moving the holder 26 in the optical axis direction X, and the alignment state is adjusted by moving the holder 26 in a direction orthogonal to the optical axis direction X. Thereafter, the columnar resin 35 is cured by being irradiated with ultraviolet rays.

  Conventionally, as shown in FIG. 14, a structure in which the holder 26 is bonded to one surface of the base material 30 with a resin 35 is generally used. However, with this fixed structure, deterioration of the optical performance due to the displacement of the laser diode 20 in the optical axis direction X due to the curing shrinkage of the resin 35 and the expansion and contraction due to the change with time cannot be solved.

  On the other hand, in the first embodiment, the holder 26 is disposed so as to be sandwiched between the projecting pieces 31 of the base material 30 in the optical axis direction X, and the gap on the minus side in the optical axis direction X formed by the sandwiching. A columnar resin 35 is disposed in the gap T ′ between T and the plus side. The gaps T and T ′ are, for example, 0.5 mm, and the adjustment allowance in the optical axis direction X is expected to be about 0.1 mm.

  After the adjustment, the columnar resin 35 disposed in one of the gaps T and T ′ is first cured, and then the columnar resin 35 disposed in the other is cured. For example, when the columnar resin 35 disposed in the gap T ′ is first cured, the holder 26 is slightly displaced to the plus side in the optical axis direction X due to the curing shrinkage. At this time, the columnar resin 35 disposed in the gap T is uncured. Next, the columnar resin 35 disposed in the gap T is cured. As a result, the holder 26 displaced to the plus side in the optical axis direction X is displaced to the minus side. FIG. 14 shows a difference between the previous curing condition and the subsequent curing condition because the regulating force acting on each columnar resin 35 and the height and cross-sectional area of the resin 35 at the start of curing differ. Thus, compared with the fixed structure in which the resin 35 is disposed only on one side, the positional deviation after adjustment can be effectively suppressed. Of course, the same applies to the case where the columnar resin 35 disposed in the gap T is first cured.

  The laser beam scanning device 1 including the light source unit 2 is mounted on the image forming apparatus 100. The columnar resin 35 expands when the temperature rises during actual use, and contracts when cooled. However, the expansion and contraction acts on the holder 26 almost equally on the plus side and the minus side in the optical axis direction X so that the expansion force and contraction force cancel each other. The position of is maintained within a range where there is no practical problem.

  By the way, the cross-sectional area of the columnar resin 35 is determined by the application amount of the resin and the gaps T and T ′ (the height of the resin). This is the same even when the columnar resin 35 is disposed at a plurality of positions on the same surface. In the case of multiple locations, it is necessary to consider the total total cross-sectional area. The curing shrinkage force has a correlation with the cross-sectional area of the columnar resin 35, and the shrinkage amount decreases as the regulation force applied at the time of curing increases. Providing a time difference in the curing of each of the columnar resins 35 arranged in the gaps T and T ′ changes the regulating force at the time of curing, and the regulating force for the resin 35 that is cured first afterwards is changed. Therefore, if the conditions for increasing the curing shrinkage force of the resin 35 to be cured later are set, the effect of suppressing the displacement of the holder 26 (laser diode 20) can be enhanced.

  Therefore, it is preferable to set the total cross-sectional areas of the columnar resins 35 in the gaps T and T ′ to be different, and it is more preferable to cure the columnar resin 35 having the smaller total cross-sectional area first. As a method of making the total cross-sectional areas different in the gaps T and T ′, (1) the gaps T and T ′ are made the same size and the amount of resin applied to the gaps T and T ′ is changed, or (2) the gap T , T ′ may have the same coating amount. In either case, although there is still a possibility of slight deviation from the complete optical adjustment position, the positional deviation is sufficiently suppressed as compared with the conventional fixing structure. In order to further enhance the suppression effect, the total cross-sectional area of the resin 35 on the side to be contracted may be increased or recured.

  In addition, the columnar resin 35 is disposed symmetrically in the optical axis direction X in one gap T and the other gap T ′, so that the direction of the curing shrinkage force is balanced, and displacement of the laser diode 20 can be effectively prevented. .

  Further, by disposing the holder 26 for holding the laser diode 20 with the gaps T and T ′, the heat dissipation is improved, and the influence of the temperature rise due to the high output of the laser diode 20 due to the high-speed drawing can be suppressed. it can. In addition, in order to fix the laser diode 20 to the holder 26, welding or adhesion may be used in addition to press-fitting. The collimator lens 21 does not necessarily have to be fixed to the base material 30 in advance, and is temporarily fixed by appropriate means, and when adjusting the positional relationship with the laser diode 20, the alignment adjustment is performed. To the base material 30.

(Refer to the second embodiment, FIGS. 8 and 9)
As shown in FIGS. 8 and 9, the light source unit 2 according to the second embodiment includes projecting pieces provided at one end of the base material 30 by projecting pieces 26 a and 26 b provided on the holder 26 holding the laser diode 20. 33 is disposed so as to be sandwiched in the optical axis direction X, and photocurable columnar resin 35 is disposed in the gaps T and T ′. Other configurations are the same as those of the first embodiment. The operational effects are the same as in the first embodiment.

  In the second embodiment, one columnar resin 35 is arranged in the gap T, two columnar resins 35 are arranged in the gap T ′, and the total cross-sectional area of the columnar resin 35 in the gaps T and T ′ is calculated. The columnar resin 35 having a smaller total cross-sectional area is hardened first. However, it is not always required to make the total cross-sectional areas of the columnar resins 35 different in the gaps T and T ′.

(Refer to the third embodiment, FIG. 10)
As shown in FIG. 10, the light source unit 2 according to the third embodiment has a columnar shape with a structure similar to that of the first embodiment between the projecting pieces 42 provided with the holder 39 for holding the collimator lens 21 on the base material 40. The resin 35 was adhesively fixed. The holder 26 for holding the laser diode 20 is also fixed between the projecting pieces 41 provided on the base material 40 by the columnar resin 35 as in the first embodiment. Further, a protrusion 11 is provided on the housing 10 of the laser beam scanning device 1, and the base material 40 is sandwiched in the optical axis direction X by the protrusion 11, and is formed between the protrusion 11 and both end faces of the base material 40. A columnar resin 35 is disposed in the gaps T and T ′.

  According to the third embodiment, the positions of the laser diode 20 and the collimator lens 21 are maintained without displacement by the respective columnar resins 35, and the positions of the base materials 40 are also maintained without displacement by the columnar resin 35.

(Characteristics required for columnar resin)
By the way, in the fixed structure, it is necessary to set the gaps T and T ′ to a dimension larger than that assuming that the processing error of the holder 26 and the base material 30 is at least 0.1 mm. When an uncured resin is formed in the gaps in a columnar shape, the resin is required to have a certain degree of viscosity. The required viscosity varies depending on the size of the gap and the assembly process. Assuming a gap of 0.1 to 1.0 mm, 6,000 to 30,000 millipascal seconds are necessary in a normal temperature environment (25 ° C.). Further, considering that the columnar resin relaxes the stress generated during curing, it is desirable that the resin has a low glass transition point. On the other hand, assuming a room temperature environment, the glass transition point is preferably about 60 ° C. or higher. Furthermore, assuming a harsh environment, if the glass transition point is too high, it causes peeling. For these reasons, the glass transition point required for the columnar resin material is desirably 110 ° C. or lower.

  By the way, the adhesive is usually used for fastening two articles in close contact with each other in a plane, but in this fixing structure, the columnar resin has an air bonding function, that is, an article (a holder and a substrate). ) At a predetermined interval as a spacer or a structure. As a result of various experiments leading to the present invention, the present inventor has found that the following various conditions exist in order to provide this function.

  First, (1) there is an affinity (adhesive force) for both the holder and the substrate, (2) it can withstand the linear expansion difference between the holder and the substrate, that is, it has the necessary elasticity. The linear expansion is intermediate between the holder and the substrate, or the deformation of the substrate having a relatively large elasticity can be regulated with a hardness equal to or higher than that of a holder having a relatively small elasticity. (3) To some extent in an uncured state It is necessary to satisfy the following requirements: (4) low irreversible deformation (creep).

  When an ordinary adhesive is applied to the member in an uncured state, for example, even if it is initially 3 mm in diameter and 1 mm in height, it expands to a diameter of 7 mm or more and a height of about 0.5 mm in a few minutes, forming a columnar shape. It is difficult to do. Although a method of maintaining the height by using a resin having a higher viscosity is conceivable, it is difficult to control the coating amount due to the high viscosity. Therefore, the height of the columnar resin can be maintained by using the following coating method.

  (1) Resin is applied to one member, the other member is immediately brought into contact with the resin, and a gap is slowly widened to form a desired interval to generate tension, thereby connecting the resin (columnar shape). maintain. (2) Resin is applied to each member, and the resin is brought into contact with each other to generate a tension to maintain the resin connection (columnar shape). (3) Resin is applied and connected at the end so as to be transmitted from one member to the other member with a gap provided between both members. In this case, the columnar resin is formed at the end of the member.

  As a result of the experiments by the present inventors, in any of the methods (1), (2), and (3), the columnar shape is provided with a wider interval than the method of maintaining the height by relying on the viscosity of the resin. I was able to maintain it. In particular, the above methods (2) and (3) are preferable, and in a room temperature environment (25 ° C.), a viscosity of 6,000 to 30,000 millipascal seconds can be formed in a columnar shape with an interval of about 1.0 mm.

  Further, as shown in FIG. 6B, the distance D from the end of the protruding piece 31 or the holder 26 to the center of the columnar resin 35 and the gap T satisfy the relationship of T ≧ 0.2 × D. Is preferred. In the case of using a photocurable adhesive as the columnar resin 35, it is necessary to increase the gap T proportionally as the distance D increases and to effectively irradiate the columnar resin 35 with light to be cured. For the convenience of assembling the light source unit 2, for example, when irradiating light from the direction of arrow E, if the distance D is large and the columnar resin 35 is hidden behind, the light does not reach the columnar resin 35. This is to avoid the problem. For example, the gap T is 0.1 mm and the dimension D is 0.5 mm.

  As the columnar resin, it is preferable to use an ultraviolet curable photocurable adhesive. This type of resin can form a joined state in a short time after position adjustment, can prevent misalignment until it is cured, and facilitates production in a short time. In addition, a monochromatic LED type irradiator for UV curing can be easily obtained, and can be cured while suppressing heat generation.

(Structure for arranging columnar resin, see FIGS. 11 to 13)
In FIG. 11, a depression 31 a for arranging the columnar resin 35 is formed on the protruding piece 31 of the base material 30. The recess 31a is formed smaller than the diameter of the columnar resin 35, but may have the same diameter or a larger diameter. The depression 31a serves as a mark when the resin is applied, and can prevent dripping in an uncured state. Furthermore, even if the projected area is the same, the ground contact area of the columnar resin 35 increases, and the bonding strength increases. Moreover, since the depression 31a functions to supply an uncured resin even when the resin 35 is cured and contracted, peeling at the time of curing is prevented. The same effect can be obtained even if the recess 31a is formed in the holder 26.

  In FIG. 12, the holder 26 is formed with a projection 26c for arranging the columnar resin 35. As shown in FIG. The protrusions 26c are formed smaller than the diameter of the columnar resin 35, but may have the same diameter or a larger diameter. The protrusion 26c can be a mark at the time of application as in the case of the recess 31a, and can form a large gap for allowing light to enter for curing. If the gap becomes large, stable photocuring can be realized without highly accurate positioning of the curing light irradiator. The same effect can be obtained even if the protrusion 26 c is formed on the protrusion 31 of the base material 30.

  In FIG. 13, holes 31 b and 26 d smaller than the diameter of the columnar resin 35 are formed in the protruding piece 31 and the holder 26 of the base material 30. The effect is the same as that of the said hollow 31a, Furthermore, it functions also as a window part of light irradiation. It is also possible to inject resin from this hole 31b.

(Summary of Examples)
In the optical element fixing structure and fixing method, the photocurable columnar resin disposed in one gap and the photocurable columnar resin disposed in the other gap may have different total cross-sectional areas. Good. In this case, it is preferable to harden the columnar resin having the smaller total cross-sectional area first. Moreover, it is preferable that columnar resin is arrange | positioned symmetrically in an optical axis direction in one clearance gap and the other clearance gap.

  The optical element may be a light emitting element or a beam shaping element. If it is a light emitting element, since the holder has a clearance gap and is fixed to a base material, heat dissipation becomes favorable. The holder may hold the light emitting element and the beam shaping element. In this case, the holder is attached to the housing of the laser beam scanning device.

  As the columnar resin, an ultraviolet curable adhesive can be suitably used. The ultraviolet curable adhesive hardly changes in quality from application to curing. The columnar resin has a glass transition point of 110 ° C. or lower and a viscosity in an uncured normal temperature state (25 ° C.) of 6,000 to 30, in order to maintain the columnar shape in an uncured state and prevent peeling or sagging. 000 millipascal seconds and a height dimension of 0.1 to 1.0 mm is preferred.

  The distance D from the end of the holder or base material to the center of the columnar resin and the gap T at the end satisfy the relationship of T ≧ 0.2 × D, that is, the distance D can be increased. For example, by increasing the gap proportionally, it is possible to effectively irradiate the columnar resin with light and realize stable photocuring.

  At least one of the holder and the base material may be provided with a recess or protrusion for arranging the columnar resin, or a hole smaller than the base of the columnar resin is formed at a position where the columnar resin is arranged. It may be. The depressions and protrusions serve as marks when the resin is applied, and can prevent dripping in an uncured state. Furthermore, even if the projection area is the same, the contact area of the columnar resin increases, and the bonding strength increases. In particular, the depression serves to supply an uncured resin when shrinking during curing, so that peeling during curing can be prevented. By forming the columnar resin on the protrusion, the substantial interval can be increased, and the path of light for curing is widened.

  The optical element fixing structure, fixing method, laser beam scanning apparatus, and image forming apparatus according to the present invention are not limited to the above-described embodiments, and can be variously modified within the scope of the gist thereof.

  For example, the arrangement and shape of the columnar resin are arbitrary. The configuration other than the light source unit is of course arbitrary, and may be a multi-beam type laser beam scanning device including a plurality of light source units.

  In particular, in the first embodiment, the holder 26 is not a simple flat plate shape, and protrusions and stepped portions may be partially formed. The holder 26 is made of metal (made of stainless steel) in consideration of heat dissipation, but may be a resin molded product other than metal if there is no problem with heat dissipation. Further, the holder 26 may be configured integrally with the laser diode 20.

1 is a schematic configuration diagram illustrating an embodiment of an image forming apparatus according to the present invention. It is a schematic perspective view which shows one Example of the laser beam scanning apparatus which concerns on this invention. It is sectional drawing of the subscanning direction which shows the light source unit provided with the collimator lens and the cylindrical lens. It is explanatory drawing which shows the method of adjusting a collimator lens and a cylindrical lens separately. It is a perspective view which shows 1st Example of the fixing structure of the optical element which concerns on this invention. The said 1st Example is shown, (A) is a top view, (B) is a front view. It is a perspective view which shows the holder which comprises the said 1st Example. It is a perspective view which shows 2nd Example of the fixing structure of the optical element which concerns on this invention. The said 2nd Example is shown, (A) is a top view, (B) is a front view. It is a front view which shows 3rd Example of the fixing structure of the optical element which concerns on this invention. The 1st example of the detail of the fixation structure of an optical element is shown, (A) is a front view, (B) is a perspective view of the principal part. The 2nd example of the detail of the fixing structure of an optical element is shown, (A) is a front view, (B) is a perspective view of a holder. It is a front view which shows the 3rd example of the detail of the fixing structure of an optical element. It is a front view which shows the fixing structure of the light source unit prior to this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laser beam scanning device 2 ... Light source unit 10 ... Housing 20 ... Laser diode 21 ... Collimator lens 26 ... Holder 26c ... Protrusion 26d ... Hole 30, 40 ... Base material 31a ... Depression 31b ... Hole 35 ... Columnar resin T, T ' ... Gap

Claims (16)

In a fixing structure of an optical element in which a holder for holding at least one optical element and a base material for attaching the holder are fastened with a photocurable columnar resin,
Arranged so that either the holder or the base material is sandwiched in the optical axis direction on the other side,
A photo-curable columnar resin is arranged in a gap located in the front and rear of the optical axis direction formed by the sandwiching,
The columnar resin disposed in one gap and the columnar resin disposed in the other gap are cured over time,
An optical element fixing structure.   2. The optical according to claim 1, wherein the photocurable columnar resin disposed in one gap and the photocurable columnar resin disposed in the other gap have different total cross-sectional areas. Element fixing structure.   3. The optical element fixing structure according to claim 1, wherein the photocurable columnar resin is arranged symmetrically in the optical axis direction in one gap and the other gap. 4.   The optical element fixing structure according to any one of claims 1 to 3, wherein the optical element is a light emitting element or a beam shaping element.   5. The optical element fixing structure according to claim 1, wherein the holder holds a light emitting element and a beam shaping element, and the base is a housing of a laser beam scanning device.   6. The fixing structure for an optical element according to claim 1, wherein the columnar resin is an ultraviolet curable adhesive.   The optical element fixing structure according to any one of claims 1 to 6, wherein the columnar resin has a glass transition point of 110 ° C or lower.   The columnar resin has a viscosity in an uncured room temperature state of 6,000 to 30,000 millipascal seconds, and a height dimension of 0.1 to 1.0 mm. An optical element fixing structure according to any one of the above.   The distance D from the end of the holder or the base material to the center of the columnar resin and the gap T at the end satisfy a relationship of T ≧ 0.2 × D. The optical element fixing structure according to claim 1.   The optical element fixing structure according to any one of claims 1 to 9, wherein a recess for arranging the columnar resin is formed in at least one of the holder and the base material.   The optical element fixing structure according to any one of claims 1 to 9, wherein a protrusion for arranging the columnar resin is formed on at least one of the holder and the base material.   The hole smaller than the base part of this columnar resin is formed in the location where the said columnar resin is arrange | positioned in at least one of the said holder and the said base material in any one of Claim 1 thru | or 9 characterized by the above-mentioned. The fixed structure of the optical element as described. In a fixing method of an optical element, in which a holder for holding at least one optical element and a base material for attaching the holder are fastened with a photo-curable columnar resin,
Arranging one of the holder and the base material so as to be sandwiched in the optical axis direction on the other side;
Arranging an uncured photo-curable columnar resin in a gap located before and after the optical axis direction formed by the sandwiching;
Adjusting the position of the optical element;
Curing the columnar resin disposed in one gap and the columnar resin disposed in the other gap over time; and
An optical element fixing method comprising the steps of:   The columnar resin disposed in one gap and the columnar resin disposed in the other gap have different total cross-sectional areas, and the columnar resin having the smaller total cross-sectional area is cured first. The method for fixing an optical element according to claim 13.   A laser beam scanning apparatus comprising the optical element fixing structure according to claim 1.   An image forming apparatus comprising the laser beam scanning device according to claim 15.

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