JP6107096B2 - Scanning lens - Google Patents

Description

  The present invention relates to a scanning lens formed of resin.

  As a scanning lens formed of resin, which is used in an optical scanning device of a laser printer, etc., a lens portion formed in a long shape in the main scanning direction, and a flange portion provided outside the lens portion in the main scanning direction, In addition, a lens provided with a lens portion and rib portions provided on both sides of the flange portion in the sub-scanning direction is known (see Patent Document 1).

JP 2008-241817 A

  By the way, in the conventional scanning lens, since the corner formed by the flange portion and the rib portion is angular, when the resin is injected into the mold to mold the scanning lens, the corner of the flange portion and the rib portion is formed. There was a problem that the fluidity of the resin deteriorated and molding defects were likely to occur.

  Therefore, an object of the present invention is to provide a scanning lens that can suppress the occurrence of molding defects.

The present invention for achieving the above-described object is a scanning lens formed of resin, which is formed in an elongated shape in the main scanning direction, and the thickness in the optical axis direction of the central portion in the main scanning direction is the main scanning. A lens part larger than the thickness in the optical axis direction at the end of the direction, a flange part extending from one end part in the main scanning direction of the lens part toward the outside in the main scanning direction, and a boundary part between the lens part and the flange part in the sub-scanning direction on both sides, and a rib portion formed respectively so as to extend along the main scanning direction.
The flange portion includes a first surface located on the outer side in the optical axis direction than the one end portion of the lens portion, and a second surface connecting the first surface and the one end portion. The ridgeline of the second surface is formed in a curved shape that is convex outward in the main scanning direction when viewed from the optical axis direction.
The thickness in the optical axis direction of the flange portion is larger than the thickness in the optical axis direction of the one end portion of the lens portion, and smaller than the thickness in the optical axis direction of the central portion of the lens portion in the main scanning direction. The flange portion is located on the inner side in the optical axis direction than the central portion of the lens surface of the lens portion in the main scanning direction.

  According to such a configuration, the cross-sectional shape near the corners of the flange portion and the rib portion can be gradually changed in the main scanning direction, so the vicinity of the flange portion and the rib portion corner when the scanning lens is molded. The fluidity of the resin can be improved. Thereby, generation | occurrence | production of the shaping | molding defect of a scanning lens can be suppressed.

  In the scanning lens described above, the rib portion has a third surface located outside the one end portion in the optical axis direction, and the first surface and the third surface are flush with each other. it can.

  According to this, since no step is formed between the first surface of the flange portion and the third surface of the rib portion, the fluidity of the resin from the rib portion to the flange portion can be improved, and the scanning lens The occurrence of molding defects can be further suppressed.

  In the scanning lens described above, the first surface may be a plane orthogonal to the optical axis direction.

  According to this, since the first surface of the flange portion can be used as a positioning surface when the scanning lens is attached to a frame such as an optical scanning device, the attachment property when the scanning lens is attached to the frame is improved. Can do. Further, the shape of the scanning lens can be simplified as compared with the case where the portion functioning as the positioning is formed separately from the first surface.

  The scanning lens described above can be configured to have a gate portion corresponding to the gate of the mold on the end surface close to the one end portion of the end surface in the main scanning direction of the scanning lens.

  According to this, when the resin is injected from the gate, the pressure of the resin flowing from the flange portion toward the rib portion becomes high, and the flow of the resin near the corner portions of the flange portion and the rib portion is likely to be disturbed. According to the present invention in which the cross-sectional shape in the vicinity of the corner can be gradually changed, the resin flow can be stabilized.

  Further, the scanning lens described above may be configured to have a gate portion corresponding to the gate of the mold on the end surface far from the one end portion of the end surface in the main scanning direction of the scanning lens.

  According to this, since the pressure of the resin injected from the gate decreases near the flange portion, the resin is less likely to flow compared to the gate side, but the cross-sectional shape near the corners of the flange portion and the rib portion is moderated. According to the present invention that can be changed, the resin can flow well from the gate toward the end face of the flange portion.

  In the above-described scanning lens, the flange portion may be provided at both ends of the lens portion in the main scanning direction.

  According to this, the resin injected from the gate can be satisfactorily flowed over the entire main scanning direction of the scanning lens.

  According to the present invention, it is possible to suppress the occurrence of molding defects in a resin scanning lens.

It is a perspective view which shows schematic structure of the optical scanning device provided with the scanning lens of this invention. It is a perspective view of the frame of the scanning lens and optical scanning device concerning one embodiment. It is the figure which looked at the scanning lens from the 1st protrusion part side. It is sectional drawing which cut | disconnected the scanning lens by the surface orthogonal to a subscanning direction. It is the figure which looked at the scanning lens from the emission side of the laser beam. It is the enlarged view of the edge part of the side far from the gate part of a scanning lens, the figure (a) seen from the 1st protrusion part side, and the figure (b) seen from the emission side of the laser beam. It is the enlarged view of the edge part near the gate part of a scanning lens, the figure (a) seen from the 1st protrusion part side, and the figure (b) seen from the emission side of the laser beam.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, the main scanning direction is the scanning direction of laser light on the surface to be scanned such as a photosensitive drum, and is the same as the longitudinal direction of the scanning lens, and the sub-scanning direction is the main scanning direction. This direction is orthogonal to both the direction and the optical axis direction of the scanning lens.

First, a schematic configuration of an optical scanning device using the scanning lens of the present invention will be described.
As shown in FIG. 1, an optical scanning device 1 according to the present embodiment includes a semiconductor laser 2 as an example of a light source, an aperture stop 3, a coupling lens 4, and a polygon mirror 5 as an example of a deflector. A scanning lens 100 and a frame 10 to which an optical component such as the scanning lens 100 is attached are mainly provided so that the laser light emitted from the semiconductor laser 2 is condensed in a dot shape on a scanning surface (not shown) and scanned. It is configured.

The semiconductor laser 2 is a known element that emits laser light.
The aperture stop 3 is formed by forming an opening 3A on a wall provided inside the frame 10, and is provided integrally with the frame 10 in this embodiment. The aperture stop 3 defines the widths of the laser light emitted from the semiconductor laser 2 in the main scanning direction and the sub-scanning direction.

The coupling lens 4 is a lens that converts the laser light that has passed through the aperture stop 3 into a light beam substantially parallel to the main scanning direction and forms an image on the mirror surface 5A of the polygon mirror 5 in the sub scanning direction.
The polygon mirror 5 is a member in which four mirror surfaces 5A are arranged at an equal distance from the rotation shaft 5B, and reflects the laser light that has passed through the coupling lens 4 by rotating at a constant speed around the rotation shaft 5B. Thus, it is deflected in the main scanning direction.

  The scanning lens 100 is a lens through which the laser light deflected by the polygon mirror 5 passes. The scanning lens 100 forms an image of a laser beam in a dot shape on a surface to be scanned (not shown) and corrects the tilt of the mirror surface 5A of the polygon mirror 5. Further, the scanning lens 100 has an fθ characteristic such that the laser beam deflected at a constant angular velocity by the polygon mirror 5 is scanned on the surface to be scanned at a constant velocity.

Next, a detailed configuration of the scanning lens 100 related to the characteristic part of the present invention will be described.
The scanning lens 100 shown in FIG. 2 is molded by injecting a molten resin into a mold having a cavity corresponding to the shape and hardening the resin. In the present invention, the specific method for molding the scanning lens is not particularly limited, and for example, an injection molding method or the like can be employed. As shown in FIG. 3, the scanning lens 100 molded by such a molding method has a parting line PL extending linearly along the main scanning direction, and further, the end surfaces 101 and 102 in the main scanning direction. One of the end faces 101 has a gate portion G corresponding to a mold gate, with the remaining gate being convex as an example.

  As shown in FIGS. 2 and 3, the scanning lens 100 includes a lens part 110, a pair of flange parts 120, a pair of rib parts 130, a first protrusion part 140, a second protrusion part 150, and a third part. The projecting portion 160 and the fourth projecting portion 170 are mainly provided. FIG. 3 shows a state where the scanning lens 100 shown in FIG. 2 is viewed from below.

  As shown in FIGS. 3 and 4, the lens unit 110 is formed in an elongated shape in the main scanning direction, and has a lens surface 110A on which laser light is incident and a lens surface 110B that emits laser light. doing. The thickness of the lens unit 110 in the optical axis direction is larger in the central portion in the main scanning direction than the end portions 111 and 112 and gradually decreases toward the end portions 111 and 112.

  The flange portion 120 extends in the main scanning direction of the lens unit 110 so as to extend from the ends 111 and 112 of the lens unit 110 in the main scanning direction to the outside in the main scanning direction, that is, in a direction away from the center of the lens unit 110. Provided at the end portions 111 and 112, respectively.

  Of the surfaces in the optical axis direction of the flange portion 120, the incident side surface 121 that is the surface on the laser beam incident side is formed so as to continuously extend from the lens surface 110A toward the end surfaces 101 and 102 of the scanning lens 100. ing. A portion of the incident side surface 121 outside the first protrusion 140 and the third protrusion 160 in the main scanning direction is formed as a plane orthogonal to the optical axis direction, and as shown in FIGS. 1 and 2, the scanning lens When 100 is attached to the frame 10, it functions as a positioning unit that determines the position of the scanning lens 100 in the optical axis direction with respect to the frame 10 by abutting against a pair of ribs 13 provided inside the frame 10.

  Returning to FIGS. 3 and 4, the emission side surface 122, which is the surface on the laser beam emission side, includes a first surface 123 positioned on the outer side in the optical axis direction than the end portions 111 and 112 of the lens unit 110, and the first surface 123. It has a surface 123 and a second surface 124 that connects the ends 111 and 112. In other words, the flange portion 120 is formed so as to protrude in the optical axis direction from the end portions 111 and 112 of the lens portion 110. As a result, the scanning lens 100 has a concave portion 103 that is recessed in the optical axis direction in the vicinity of the boundary portions B1 and B2 between the lens portion 110 and the flange portion 120. Of the emission side surface 122, the first surface 123 is formed as a plane orthogonal to the optical axis direction, and the second surface 124 is formed as a surface inclined with respect to the optical axis direction.

  As shown in FIGS. 1 and 2, the frame 10 is provided with the ribs 13 at both ends in the main scanning direction, which serve as a reference for the position in the optical axis direction when the scanning lens 100 is attached. Further, plate-like resin springs 14 are provided at positions facing the ribs 13, respectively. In the scanning lens 100, the flange 120 is inserted between the rib 13 and the resin spring 14, and the first surface 123 is urged by the resin spring 14, so that the incident side surface 121 is pressed against the rib 13. In this state, the frame 10 is supported. In the present embodiment, since the first surface 123 is a plane orthogonal to the optical axis direction, the flange portion 120 can be stably urged toward the rib 13 by the resin spring 14.

  As shown in FIGS. 3 and 5, the rib portion 130 includes the boundary portions B <b> 1 and B <b> 2 between the lens portion 110 and the flange portion 120, along the main scanning direction on both sides of the lens portion 110 and the flange portion 120 in the sub-scanning direction. Are formed to extend. More specifically, when viewed from the sub-scanning direction, the rib portion 130 includes a wide portion 130A that is a central portion in the main scanning direction, a narrow portion 130B that is both side portions in the main scanning direction, a wide portion 130A, and a narrow portion. It has the connection part 130C which connects 130B.

  The narrow portion 130B protrudes in the optical axis direction from the bottom of the concave portion 103 (see FIG. 4) formed by the lens portion 110 and the flange portion 120. The third surface 132 that is the surface on the laser beam emission side of the narrow portion 130 </ b> B is formed to be flush with the first surface 123 of the flange portion 120.

  At the center in the main scanning direction of the wide portion 130A, a convex portion 133 that protrudes outward in the optical axis direction is provided. As shown in FIGS. 1 and 2, one of the convex parts 133 is engaged with the concave part 11 provided in the frame 10 when the scanning lens 100 is attached to the frame 10, so that the scanning lens for the frame 10 is engaged. It functions as a positioning unit that determines the position of 100 in the main scanning direction.

  As shown in FIG. 6B and FIG. 7B, the ridgeline EL of the first surface 123 and the second surface 124 of each flange portion 120 is viewed as a whole in the main scanning direction when viewed from the optical axis direction. It has a curved shape that protrudes outward, and is formed so as to be continuous with the inner edge of the rib portion 130 in the sub-scanning direction. More specifically, in the present embodiment, the ridgeline EL is a central portion in the sub-scanning direction and extends substantially straight along the sub-scanning direction, and from the end of the straight portion EL1 to the edge of the rib portion 130. It mainly includes a curved portion EL2 that extends while curving so as to be continuous. In the present invention, the ridgeline between the first surface and the second surface has a curved portion that is larger than the roundness of corners and corners that are normally formed when the scanning lens is molded. For the ridgeline EL, L1 <L2, where L1 is the length of the straight line portion EL1 in the sub-scanning direction and L2 is the length of the curved portion EL2 in the sub-scanning direction.

  The curved shape of the curved portion EL2 and the curved shape of the corner portions 113 of the end portions 111 and 112 of the lens portion 110 are different from each other. The curved shape is gentler than that of the portion 113. The portions on both sides of the second surface 124 in the sub-scanning direction have the first surface 123 and the end portions 111 and 112 so that the curved shape gradually approaches the shape of the corner portion 113 as it goes from the curved portion EL2 to the corner portion 113. And is connected smoothly.

  As shown in FIG. 5, the first protrusion 140 and the third protrusion 160 are on one side in the sub-scanning direction of the scanning lens 100, specifically on the outer side in the sub-scanning direction from the side surface 134 of one rib 130. It is formed so as to protrude downward. Further, the second protrusion 150 and the fourth protrusion 170 are on the side opposite to the above-described one side of the scanning lens 100, specifically on the upper side in the sub-scanning direction from the side 135 of the other rib part 130. It is formed so as to protrude toward.

  More specifically, as shown in FIGS. 6A and 6B, the first projecting portion 140 includes a boundary portion B2 between the lens portion 110 and the flange portion 120, and the lens portion 110 and the flange as viewed from the sub-scanning direction. It is provided at a position overlapping both of the recesses 103 formed by the portion 120. On the other hand, the 2nd protrusion part 150 is formed in the symmetrical position and the symmetrical shape with the 1st protrusion part 140 on both sides of boundary part B2.

  Further, as shown in FIGS. 7A and 7B, the third projecting portion 160 is located on the outer side in the main scanning direction than the boundary portion B1 between the lens portion 110 and the flange portion 120 when viewed from the sub scanning direction. , Provided at a position adjacent to the boundary portion B1. On the other hand, the 4th protrusion part 170 is formed in the symmetrical position and the symmetrical shape with the 3rd protrusion part 160 on both sides of the flange part 120. As shown in FIG.

  The first protrusion 140 and the third protrusion 160 are provided at symmetrical positions with respect to the centers of the lens surfaces 110A and 110B, and the second protrusion 150 and the fourth protrusion 170 are the lens surfaces 110A and 110B. It is provided at a symmetrical position with respect to the center.

  The first protrusion 140, the second protrusion 150, the third protrusion 160, and the fourth protrusion 170 are respectively separated from the parting line PL as shown in FIG. 6A and FIG. It is formed in a substantially chevron shape so that the width in the main scanning direction gradually decreases as it moves away in the optical axis direction. Thus, when the scanning lens 100 is molded, the projections 140 to 170 are less likely to become resistance when the scanning lens 100 is taken out of the mold, so that the scanning lens 100 can be easily taken out of the mold. 100 productivity can be improved.

  The first protrusion 140, the second protrusion 150, the third protrusion 160, and the fourth protrusion 170 are each formed in a planar shape in which the outer surface in the sub-scanning direction is orthogonal to the sub-scanning direction. Yes. The sub-scanning direction outer surfaces 141 and 161 of the first protrusion 140 and the third protrusion 160 are the bottom walls of the frame 10 when the scanning lens 100 is attached to the frame 10 as shown in FIGS. 12 functions as a positioning unit that determines the position of the scanning lens 100 in the sub-scanning direction with respect to the frame 10.

According to this embodiment described above, the following effects can be obtained.
The scanning lens 100 is formed by the flange portion 120 and the rib portion 130 because the ridgeline EL of the first surface 123 and the second surface 124 is formed in a curved shape that is convex outward in the main scanning direction. Since the corners to be formed are not angular, the cross-sectional shape in the vicinity of the corners can be gradually changed in the main scanning direction. Thereby, since the fluidity | liquidity of resin near the corner part of the flange part 120 and the rib part 130 at the time of shaping | molding the scanning lens 100 can be improved, generation | occurrence | production of the shaping | molding defect of the scanning lens 100 can be suppressed.

  Further, since the first surface 123 of the flange portion 120 and the third surface 132 of the rib portion 130 are flush with each other, no step is formed between the first surface 123 and the third surface 132. The fluidity of the resin from the rib part 130 to the flange part 120 can be improved, and the occurrence of defective molding of the scanning lens 100 can be further suppressed.

  Further, since the ridge line EL of the flange portion 120 having the gate portion G is formed in the above-described curved shape, the fluidity of the resin can be stabilized when the scanning lens 100 is molded. In the vicinity of the flange portion 120 having the gate portion G, the resin is injected from the gate, so that the pressure of the resin increases and the flow of the resin near the corner portions of the flange portion 120 and the rib portion 130 tends to be disturbed. This is because, in the embodiment, the cross-sectional shapes near the corners of the flange portion 120 and the rib portion 130 change gently.

  On the other hand, the ridgeline EL of the flange portion 120 on the side far from the gate portion G is formed in the above-described curved shape, so that the resin injected from the gate is good toward the end surface 102 on the side opposite to the gate portion G side. Can be shed. Since the pressure of the injected resin decreases near the flange portion 120 on the side far from the gate portion G, the resin is less likely to flow compared to the gate portion G side, but in this embodiment, the flange portion 120 and the rib portion 130 are used. This is because the cross-sectional shape in the vicinity of the corner changes gradually.

  Further, in each of the flange portions 120 provided at both end portions of the lens portion 110, the ridgeline EL is formed in the above-described curved shape, so that the resin injected from the gate is spread over the entire main scanning direction of the scanning lens 100. It can flow well.

  The scanning lens 100 has a concave portion 103 near the boundary portion B2 between the lens portion 110 and the flange portion 120, thereby reducing the thickness in the optical axis direction. However, the first protrusion 140 and the rib portion 130 are near the boundary portion B2. Is provided, the cross-sectional area in the vicinity of the boundary portion B2 can be increased as compared with the case where the first projecting portion 140 and the rib portion 130 are not provided. In other words, the scanning lens 100 can mitigate the reduction in the cross-sectional area near the boundary portion B <b> 2 with respect to the cross-sectional area of the flange portion 120. Thereby, since the fluidity | liquidity of resin of the boundary part B2 vicinity at the time of shape | molding the scanning lens 100 can be improved, the moldability of the scanning lens 100 can be improved.

  In particular, in the present embodiment, the second protrusion 150 is provided on the opposite side of the first protrusion 140, and each protrusion 140, 150 is provided at a position overlapping both the boundary portion B2 and the recess 103. Since each protrusion part 140,150 becomes long by being in an optical axis direction, the cross-sectional area of boundary part B2 vicinity can be enlarged more. In the present embodiment, since the first protrusion 140 and the second protrusion 150 are formed symmetrically, the flow of resin near the boundary portion B2 can be made substantially uniform on both sides in the sub-scanning direction. Accordingly, the fluidity of the resin in the vicinity of the boundary portion B2 at the time of molding can be further improved, so that the moldability of the scanning lens 100 can be further improved.

  In addition, in the configuration where the thickness of the lens part in the optical axis direction is larger in the center part than in the end part, it is necessary to secure a certain thickness of the end part in order to ensure the fluidity of the resin near the end part during molding. However, in this embodiment, the fluidity of the resin in the vicinity of the boundary portion B2 (end portion 112) can be improved, so that the thickness of the end portion 112 can be made thinner than the conventional one. In particular, in the present embodiment, the thickness of the end portion 112 in the optical axis direction is the smallest (thin) among the thicknesses of the lens portion 110 in the optical axis direction. Thereby, the scanning lens 100 can be thinned in the optical axis direction as a whole.

  Further, in the configuration having the gate portion G on the end surface 101 on the side far from the first projecting portion 140, the pressure of the resin injected from the gate is reduced in the vicinity of the boundary portion B2. In the embodiment, since the fluidity of the resin in the vicinity of the boundary portion B <b> 2 can be improved, the resin can flow well from the end surface 101 on the gate side toward the end surface 102.

  In the present embodiment, since the surface 141 as the positioning portion is provided on the first projecting portion 140 formed in the vicinity of the boundary portion B2, the surface 141 can be formed with high accuracy. This is because in the vicinity of the boundary portion B2, the cavity of the mold is narrower than that of the flange portion 120, and the pressure of the resin is increased during molding, so that sink marks and the like are unlikely to occur.

  In the present embodiment, since the thickness in the optical axis direction is larger than the boundary portions B1 and B2 between the lens portion 110 and the flange portion 120, the incident side surface 121 as a positioning portion is provided on the flange portion 120 having high strength. Therefore, deformation of the scanning lens 100 when the scanning lens 100 is attached to the frame 10 can be suppressed.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. About a concrete structure, it can change suitably in the range which does not deviate from the meaning of this invention as follows.

  In the embodiment, the first protrusion 140 is provided at a position overlapping both the boundary portion B2 between the lens portion 110 and the flange portion 120 and the concave portion 103 formed by the lens portion 110 and the flange portion 120. However, the present invention is not limited to this. For example, the 1st protrusion part may be provided so that only the position which overlaps the boundary part of a lens part and a flange part may be provided.

  In the above embodiment, the first protrusion 140 provided at a position overlapping the boundary portion between the lens portion 110 and the flange portion 120 is formed only on one side of the scanning lens 100 in the main scanning direction. It is not limited to this. For example, the first protrusions of the present invention may be formed on both sides of the scanning lens 100 in the main scanning direction. Specifically, for example, in the above embodiment, the third protrusion 160 may be provided at a position overlapping the boundary portion B1.

In the said embodiment, although the 2nd protrusion part 150 was provided in the other side of the 1st protrusion part 140, this invention is not limited to this, For example, the structure which is not provided with a 2nd protrusion part may be sufficient. .
In addition, the specific structure of the protrusion parts 140-170 shown by the said embodiment is an example, and this invention is not limited to the structure of the said embodiment. For example, the projecting portion may be formed in a columnar shape or may be formed in a substantially hemispherical shape.

  In the above-described embodiment, the incident side surface 121 of the flange portion 120 illustrated as a positioning portion for determining the position of the scanning lens 100 in the optical axis direction. However, the present invention is not limited to this, and is not limited to this. The form which the 1st surface 123 which is a plane orthogonal to may function as a positioning part may be sufficient. As described above, since the scanning lens has the positioning portion, the attachment property of the scanning lens to the frame of the optical scanning device can be improved. Further, the shape of the scanning lens can be simplified as compared with the configuration in which the portion functioning as the positioning is formed separately from the incident side surface 121 and the first surface 123 of the above embodiment.

  In the above-described embodiment, the flange portion 120 is provided at each of the end portions 111 and 112 of the lens portion 110. However, the present invention is not limited to this, for example, only at one end portion of the lens portion in the main scanning direction. It may be provided. When the flange portion is provided only at one end portion of the lens portion, the scanning lens may have a gate portion on an end surface close to one end portion of the lens portion in the end surface in the main scanning direction. And the structure which has a gate part in the end surface far from the one end part of a lens part among the end surfaces of a main scanning direction may be sufficient.

  The specific configuration of the rib portion 130 shown in the embodiment is an example, and the present invention is not limited to the configuration of the embodiment. For example, the rib portion may be formed so as to completely cover both the lens portion and the flange portion when viewed from the sub-scanning direction.

  The specific configurations of the lens unit 110 and the flange unit 120 shown in the embodiment are examples, and the present invention is not limited to the configuration of the embodiment. For example, the flange portion may have a curved first surface.

  In the embodiment described above, the scanning lens 100 has the parting line PL near the center of the lens unit 110 in the optical axis direction, but the present invention is not limited to this. That is, the position where the parting line is formed in the present invention is not particularly limited. For example, the scanning lens may have a parting line at the end of the lens unit in the optical axis direction.

  In the above embodiment, the polygon mirror 5 has four mirror surfaces 5A. However, the present invention is not limited to this, and for example, the number of mirror surfaces may be six. In the above embodiment, the polygon mirror 5 is exemplified as the deflector. However, the present invention is not limited to this, and may be, for example, a vibrating mirror that deflects light by swinging. Moreover, although the semiconductor laser 2 as a light source was illustrated in the said embodiment, this invention is not limited to this, Light sources other than a semiconductor laser may be sufficient.

DESCRIPTION OF SYMBOLS 100 Scan lens 101 End surface 102 End surface 110 Lens part 111 End part 112 End part 120 Flange part 123 1st surface 124 2nd surface 130 Rib part 132 3rd surface B1 Boundary part B2 Boundary part EL Ridge line G Gate part

Claims (9)

A scanning lens molded of resin,
A lens portion that is formed in an elongated shape in the main scanning direction, and the thickness of the central portion in the main scanning direction in the optical axis direction is larger than the thickness in the optical axis direction of the end portion in the main scanning direction ;
A flange portion extending from the one end portion in the main scanning direction of the lens portion toward the outside in the main scanning direction;
Rib portions respectively formed so as to extend along the main scanning direction on both sides in the sub scanning direction of the boundary portion between the lens portion and the flange portion,
The flange portion includes a first surface located outside the one end portion of the lens portion in the optical axis direction, and a second surface connecting the first surface and the one end portion,
The ridge lines of the first surface and the second surface are formed in a curved shape that protrudes outward in the main scanning direction when viewed from the optical axis direction .
The thickness of the flange portion in the optical axis direction is larger than the thickness of the one end portion of the lens portion in the optical axis direction and smaller than the thickness of the central portion of the lens portion in the main scanning direction. And
The scanning lens according to claim 1, wherein the flange portion is positioned on the inner side in the optical axis direction than the central portion of the lens surface of the lens portion in the main scanning direction . The rib portion has a third surface located outside the one end portion in the optical axis direction at a portion corresponding to the one end portion,
The scanning lens according to claim 1, wherein the first surface and the third surface are flush with each other.   The scanning lens according to claim 1, wherein the first surface is a plane orthogonal to the optical axis direction.   The gate part corresponding to the gate of a metal mold | die is provided in the end surface close | similar to the said one end part among the end surfaces of the scanning lens of the main scanning direction, The Claim 1 characterized by the above-mentioned. Scanning lens.   The gate part corresponding to the gate of a metal mold | die is provided in the end surface far from the said one end part among the end surfaces of the main scanning direction of a scanning lens, The Claim 1 characterized by the above-mentioned. Scanning lens.   The scanning lens according to any one of claims 1 to 3, wherein the flange portion is provided at each of both end portions of the lens portion in the main scanning direction. A protrusion that protrudes from the side surface in the sub-scanning direction of the scanning lens toward the outside in the sub-scanning direction;
The said protrusion part is provided in the position which overlaps with the boundary part of the said lens part and the said flange part seeing from a subscanning direction, The any one of Claim 1-6 characterized by the above-mentioned. Scanning lens. The rib portion has a third surface located outside the one end portion in the optical axis direction at a portion corresponding to the one end portion,
8. The scanning lens according to claim 1, wherein a central portion of the lens portion in the main scanning direction is located on the outer side in the optical axis direction than the third surface. 9. The rib portion is
A portion corresponding to a central portion of the lens portion in the main scanning direction, and a wide portion located outside the central portion of the lens surface of the lens portion in the main scanning direction in the optical axis direction;
A portion corresponding to the one end, and a narrow portion having the third surface;
It is a part which connects the said wide part and the said narrow part, It has a connection part from which the thickness of an optical axis direction becomes large continuously toward the said wide part from the said narrow part. Item 9. The scanning lens according to Item 8.

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