JP5063998B2 - Optical component and optical scanning unit - Google Patents

Description

  The present invention relates to an optical component and an optical scanning unit using the same.

  An optical scanning device of a multicolor image forming apparatus that guides each beam emitted from a plurality of laser elements onto a photoconductor via a deflecting unit and an imaging unit, and forms an image on the photoconductor according to image information. There is. In recent years, in order to cope with higher speed and higher image quality of multicolor image forming apparatuses, four photosensitive drums are arranged in the direction of the output paper, and simultaneously exposed with beams corresponding to the respective photosensitive drums. Digital copying machines and laser printers have been put to practical use in which images developed by developing devices of different colors (yellow, magenta, cyan, and black) are sequentially transferred and superimposed to form a color image.

  In such an image forming apparatus, a plurality of scanning means corresponding to each color is used when performing optical scanning. However, a large space is required to arrange the scanning means, and the entire apparatus becomes large.

  For this reason, as in the invention disclosed in Patent Document 1, a method is proposed in which a plurality of beams are incident on a single deflector and scanned, and optical elements (imaging elements) are stacked and arranged.

  In order to compensate for the above-mentioned drawbacks, an image forming means for forming an image forming means is provided for each beam by allowing a plurality of beams to be incident on a single deflector and scanning, and forming an image on a corresponding photosensitive member for each beam. Patent Documents 1 and 2 disclose a method of integrally configuring image elements in a layered manner in the sub-scanning direction. By integrally forming the imaging elements in a layered manner in the sub-scanning direction, it is possible to shorten the interval of overlapping the polarizing means (polygon mirror), or it is possible to serve as a single polygon mirror. The load on the motor for rotating the motor can be reduced, and the size can be reduced.

  In addition, as a method of integrally configuring the imaging elements in a layered manner in the sub-scanning direction, a method of integrating the imaging elements corresponding to each beam by bonding (adhesion), or a layered imaging element is used. There is a method of forming by integral molding with resin.

In recent years, these imaging elements have been replaced from glass to plastic due to demands for cost reduction and advances in molding technology.
In the case where the imaging elements are manufactured by integral molding, the arrangement accuracy of each imaging element can be mold accuracy, so that high accuracy can be easily obtained, but on the other hand, the imaging element becomes thicker. For this reason, in order to form the optical surface with high accuracy, or when the imaging element is a lens, the inside of the lens is made uniform (with little internal distortion). Necessary. Furthermore, since a considerably long time is required for cooling the resin at the time of molding, there is a problem that the cost is increased.

  Further, when the imaging elements are integrated by coupling, high shape accuracy (flatness) is required for the joint surface of the imaging elements in order to obtain the placement accuracy of the imaging elements. However, when the imaging element is a lens, in order to obtain a desired imaging performance, the lens thickness (thickness in the direction of passage of light) is thick, and the lens thickness is partially changed to become an uneven thickness. For this reason, in order to process the lens surface shape with high accuracy and the inside to be uniform, a considerably advanced molding technique is required. In the case of molding this thick / uneven shape, sink marks are likely to occur in the conventional injection molding method due to large volume shrinkage during the resin cooling process. In particular, in the case of an uneven thickness shape, a molding failure called sink occurs in the thick portion. If the resin filling amount in the mold is increased in order to prevent this sink, the distortion inside the lens increases, which adversely affects the optical performance.

  Therefore, as a method for improving the drawbacks of the conventional injection molding method and forming a thick / uneven shape, molding is performed with low pressure and low filling as in the invention disclosed in Patent Document 3, and a non-transfer surface ( A method has been proposed in which concave portions (sink marks) due to non-transfer are forcibly generated on a surface that does not require functional shape transfer) to ensure the shape accuracy of the transfer surface while reducing internal distortion. FIG. 8 shows an example of such an optical element.

  However, as shown in FIG. 8, burrs 4 may occur on the outer periphery (contour) of the recess (sink) 3. FIG. 9 shows the state of the molded product in the mold. At the time of molding, the mold member 11 is slid to generate a recess (sink). Therefore, there is a gap between the mold members 10 and 11, but the resin that has entered the gap becomes the burr 4 shown in FIG. When these optical elements are laminated or bonded to the mounting surface, the burr 4 interferes to cause a problem that the mounting position accuracy is lowered or cannot be bonded.

In Patent Document 4, the above-mentioned problem is obtained by providing a concave surface not transferred to the mold wall surface forming the surface and at least one step surface (convex surface), and using this surface as a receiving surface at the time of joining. Has solved.
JP-A-4-127115 Japanese Patent Laid-Open No. 10-148777 JP-A-11-28745 JP 2003-177214 A

  However, in the invention disclosed in Patent Document 4, since the convex portion is provided on the optical element, the portion becomes thick, so that the end surface of the convex portion is sinked, and a sufficient joint surface (flatness) can be obtained. Have difficulty. In addition, the thickness of the optical element increases the cooling time of the optical element, leading to an increase in cost. Furthermore, because of the convex shape, the height dimension of the optical element is increased. If the height dimension of the stacked optical elements is increased, the distance between the optical axes of the optical elements is increased, and in the case of using one polarizing element (polygon mirror), the optical surface has to be widened. There is a problem that the cost increases.

  The present invention has been made in view of such problems, and an object thereof is to provide an optical component that can be combined with high accuracy and can be formed at low cost, and an optical scanning unit using the optical component.

In order to achieve the above object, the present invention provides an optical component in which a plurality of optical elements stacked in layers are integrated by bonding, and the surface is formed in a plane including at least one bonding surface of the optical elements. An incomplete transfer portion formed by incomplete transfer of the cavity shape of the mold to be formed, and a recess provided on a surface facing the incomplete transfer portion of another optical element adjacent to one optical element at the time of joining, Each of the plurality of optical elements is formed with the incomplete transfer portion and the concave portion, and the concave portion is formed by a convex-shaped portion in the mold, and it characterized in that it is formed to a size encompassing the contour of the incomplete transfer portion.

  According to the present invention, it is possible to provide an optical component that can be combined with high accuracy and can be formed at low cost, and an optical scanning unit using the optical component.

[First Embodiment]
A first embodiment in which the present invention is suitably implemented will be described. FIG. 1A shows the configuration of the optical element according to this embodiment. FIG. 1B shows the appearance of an optical component joined in layers.
In sink induction molding that forcibly creates a gap between the resin and the cavity piece, minute burrs 4 are generated on the outer periphery (contour) of an arbitrary sink shape 3. Here, the height dimension of the burr 4 is b. The surface 5 facing the sinking surface 2 has a sink shape 3 with a depth of a so that the optical elements 2 can be laminated with the sinking surface 2 and the surface 5 facing this surface without interference of the burr 4. A larger concave shape was provided. Here, a> b in order to prevent interference.
In addition, since the optical element is thinned by the depth of the concave shape, the cooling time of the molded product can be shortened, and the optical element can be molded at low cost.

  FIG. 2 shows a state of the mold in which the molded product has a gradient with respect to the mold release direction. Since the molded product has a gradient with respect to the mold release direction, the mold release resistance mainly due to friction is reduced, and the burden on the molded product when taking out is reduced. Thereby, the distortion of the optical element is reduced and the optical characteristics are improved. That is, since the deformation of the optical element is reduced, the shape accuracy of the transfer surface can be increased.

[Second Embodiment]
A second embodiment in which the present invention is suitably implemented will be described. FIG. 3A shows the configuration of the optical element according to this embodiment. In the present embodiment, as a method for avoiding interference, a sink surface is generated on the bottom surface of the concave amount a. Thereby, even if the burr | flash 4 arises on a sink surface outer periphery, as shown to Fig.3 (a), the interference at the time of joining is avoided. However, the concave amount a is a> b with respect to the burr height b.

  FIG. 3B shows the appearance of an optical component in which two optical elements are formed in layers. By reducing the thickness of the optical element by the depth of the concave shape, the cooling time of the molded product can be shortened, and the cost can be reduced.

  FIG. 4 shows a state of a mold in a case where a sink surface is provided on the concave bottom surface and the molded product has a gradient with respect to the mold release direction. Since the molded product has a gradient with respect to the mold release direction, the mold release resistance mainly due to friction is reduced, and the burden on the molded product when taking out is reduced. That is, since the deformation of the optical element is reduced, the shape accuracy of the transfer surface can be increased.

[Third Embodiment]
A third embodiment in which the present invention is preferably implemented will be described. FIG. 5A shows the configuration of the optical element according to this embodiment. In this embodiment, a sink surface is provided on both surfaces of the optical element. Even if burrs 4 occur on the outer periphery of the sink surface on both sides, interference at the time of joining is avoided by having the concave shape 6 on one side. FIG. 5B shows the appearance of an optical component in which two optical elements are joined in layers. Further, since the optical element is thinned by the depth of the concave shape 6, the cooling time of the molded product can be shortened, and the cost can be reduced.

  In any of the first to third embodiments described above, as a resin used for molding, a resin that transmits ultraviolet rays is used, and a plurality of optical elements are set in an adhesive jig so as to be layered, and ultraviolet rays are emitted. It is good to cure by irradiation. By using a photocurable adhesive, the adhesive can be cured after confirming the accuracy of the joining position. Further, since the curing time of the adhesive is short, the productivity can be improved as compared with the case of using another adhesive.

  Further, as shown in FIG. 6, the projection 12 added to the optical element can be positioned accurately and easily by abutting against the abutting member (reference position) 13. Thereby, an inexpensive optical component with high surface accuracy can be realized.

  In addition, as shown in FIG. 7, by making the thermal expansion coefficient of the optical element and the adhesive that are joined together in a plurality of layers substantially the same, the difference in expansion and contraction is reduced even in an environment where temperature changes can occur. Generation of distortion is avoided. When using an optical component with multiple optical elements in an environment where temperature changes occur, if the optical expansion coefficient of each optical element is different, the amount of deformation will be different. Acts, and this force deteriorates the shape accuracy and arrangement accuracy of the optical element itself. For this reason, by making the linear expansion coefficient the same, the amount of expansion and contraction becomes equal, and highly accurate joining can be maintained.

  In addition, when the optical elements are joined, the transmitted light is incident on the optical elements, and the joining position of the optical elements is adjusted while detecting the position of the emitted light with an eccentric microscope or the like, so that the optical elements can be positioned with high accuracy. Thereby, the arrangement accuracy of the optical element can be further improved, and the optical performance can be improved.

  In the optical scanning unit on which the optical component according to any of the first to third embodiments is mounted, when the optical component in which a plurality of optical elements are bonded in layers is bonded to the housing, the imperfect transfer portion is used as a bonding surface. Even if it is used, since it can be joined without interference of protrusions (burrs), it is not necessary to devise any means on the receiving surface of the housing. For this reason, the optical scanning unit can be manufactured with high accuracy and at low cost.

  In addition, the said embodiment is an example of suitable implementation of this invention, and various deformation | transformation are possible for this invention, without being limited to this.

It is a figure which shows the structure of the optical element concerning 1st Embodiment which implemented this invention suitably. It is a figure which shows the cross section of the optical element concerning 1st Embodiment, and the metal mold | die used for the shaping | molding. It is a figure which shows the structure of the optical element concerning 2nd Embodiment which implemented this invention suitably. It is a figure which shows the cross section of the optical element concerning 2nd Embodiment, and the metal mold | die used for the shaping | molding. It is a figure which shows the structure of the optical element concerning 3rd Embodiment which implemented this invention suitably. It is a figure which shows the structure of the optical element which provided the butting part. It is a figure which shows the optical component which joined the several optical element with substantially the same thermal expansion coefficient in layered form. It is a figure which shows the structure of the conventional optical element. It is a figure which shows the cross section of the metal mold | die used for the conventional optical element and its shaping | molding.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical element 2 Sink surface 3 Sink shape 4 Burr 5 Surface which faces a sink surface 6 Recessed part 7, 8, 9, 10, 11 Mold member 12 Protrusion 13 Abutting member

Claims (5)

An optical component in which a plurality of layered optical elements are integrated by bonding,
An incomplete transfer portion formed by incomplete transfer of a cavity shape of a mold forming the surface in a surface including at least one bonding surface of the optical element, and another adjacent to one optical element at the time of bonding A concave portion provided on a surface facing the incomplete transfer portion of the optical element ,
In each of the plurality of optical elements, the incomplete transfer portion and the recess are formed,
2. The optical component according to claim 1, wherein the concave portion is formed by a convex portion of the mold, and is formed in a size that includes the outline of the incomplete transfer portion in the optical element stacked in a layered manner.   The optical component according to claim 1, wherein the concave portion has a draft in a direction of releasing from the mold during molding.   3. The optical component according to claim 1, wherein the optical element is coupled to another optical element on the bonding surface by a photo-curing adhesive. The optical component according to any one of claims 1 to 3 , wherein the optical elements are bonded after optical axis alignment. An optical scanning unit on which the optical component according to any one of claims 1 to 4 is mounted.

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