JP5615666B2 - Lens unit and manufacturing method thereof - Google Patents

Description

  The present invention relates to a lens unit configured by stacking a plurality of resin lenses, and a manufacturing method thereof.

  A lens using a resin material such as plastic (hereinafter referred to as a resin lens) is known. Such a resin lens can be manufactured with high accuracy at a relatively low cost by die molding such as injection molding. For this reason, resin lenses are widely used in optical devices such as projectors.

  In an optical device, an optical system is often configured by stacking a plurality of resin lenses in the optical axis direction. In this case, each resin lens is individually bonded to the lens frame and attached to the optical device in a state of being held integrally with the lens frame. However, in recent years, with the demand for downsizing of the entire device, resin lenses and lens frames have also been downsized, and each resin lens has been individually attached to the lens frame. It is becoming difficult to bond.

  In order to solve such problems, it is possible to construct a lens unit in which each resin lens is integrated by directly bonding each resin lens with a plurality of resin lenses stacked in the optical axis direction. It is proposed in Document 1 and the like. If the lens unit is configured in this way and this lens unit is incorporated in the lens frame, it is not necessary to individually bond each resin lens to the lens frame, so that the resin lens and the lens frame can be easily reduced in size. it can.

  Moreover, in patent document 1, in the state which incorporated each resin lens in the jig | tool and performed positioning of each resin lens, it apply | coats an adhesive to the part of the side surface which each resin lens contacts, To be glued. If it carries out like this, it can carry out simply and appropriately only by integrating the optical axis alignment of each resin lens in a jig, and a highly accurate lens unit can be manufactured efficiently.

  By the way, in a resin lens manufactured by mold molding, a trace of an injection port (gate) for injecting resin into a hollow portion in the mold (hereinafter referred to as a gate trace) is inevitably generated. If the gate mark is projected from the side surface of the resin lens, when the lens unit is assembled into the lens frame, the gate mark becomes an obstacle and the lens unit is difficult to enter the lens frame. In addition, when the lens unit is assembled into the lens frame, the gate trace portion is in point contact with the lens frame, which causes backlash between the lens unit and the lens frame, and the optical axis shift of the lens unit. It becomes the factor of. It can be considered that the gate mark is flush with the side surface, but this increases the number of steps to be scraped, leading to a decrease in the productivity and cost of the lens unit.

  Therefore, in resin lenses, a so-called D-cut is used to form a recessed portion slightly recessed from the surroundings on the side surface, and a protruding gate mark is formed in the recessed portion so as not to protrude outward from the side surface. . In this way, the gate trace does not get in the way when incorporated into the mirror frame, and the gate trace portion does not make point contact with the mirror frame. Furthermore, since it is not necessary to clean the gate trace, the lens unit productivity is not reduced and the cost is not increased.

JP 2007-94241 A

  In the method of applying an adhesive to the side surface of each resin lens and bonding each resin lens as in Patent Document 1, the cured adhesive swells so as to protrude from the side surface of each resin lens, and the case of a gate trace Similarly to this, there is a problem that this raised part interferes with the incorporation into the lens frame and causes a shift in the optical axis. Although it is conceivable that the adhesive is thinly applied so as not to rise, there is a concern that the adhesion strength between the resin lenses may be easily peeled off due to an impact or the like due to insufficient adhesion strength.

  In addition, each resin lens is generally stacked with the surfaces (so-called edge surfaces) formed in the vicinity of the outer periphery in contact with each other, and an adhesive is applied to the contact surface to bond each resin lens. Is also possible. However, in the method of applying the adhesive to the contact surface, the adhesive protrudes into the inner space sealed by each resin lens, and the protruded adhesive adversely affects the optical characteristics of the lens unit. There is concern. Therefore, a method of applying an adhesive to the contact surface is also not realistic.

  The present invention has been made in view of the above problems, and in a lens unit configured by stacking a plurality of resin lenses, even when the resin lenses are bonded to each other, from the side surface of each resin lens. An object is to prevent the adhesive from protruding and to obtain sufficient adhesive strength.

  In order to achieve the above object, the present invention has a concave portion formed so as to cut out a part of a side surface, and a gate which is a trace at the time of mold forming in the concave portion so as not to protrude outward from the side surface. In a lens unit configured by stacking a plurality of resin lenses having traces, an adhesive in which the positions of the gate traces of adjacent ones are shifted around the optical axis and the resin lenses are superimposed and applied in the recesses The resin lenses are bonded to each other.

  It is preferable that the amount of deviation of the gate trace between the adjacent resin lenses around the optical axis is approximately 180 degrees.

  Each resin lens is formed with an annular plane portion that is a plane substantially orthogonal to the optical axis in the vicinity of the outer periphery of the front surface and the rear surface, and each resin lens is overlapped by contacting each of these plane portions. Preferably, the concave portion is formed shallower than the width of the planar portion, and is in contact with the planar portion of the adjacent resin lens.

  Each of the resin lenses is preferably formed in a disc shape, and the concave portion is formed in a shape in which the side surface which is a circumferential surface is cut out by a plane substantially parallel to the optical axis.

  It is preferable that the gate mark is formed in a protruding shape whose height is adjusted so as to be narrower than the width of the concave portion and not to protrude outward from the side surface, and is arranged near the center of the concave portion.

  In addition, the present invention has a plurality of sheets having a recessed portion formed so as to cut out a part of the side surface, and having a gate mark that is a mark at the time of molding a mold in the recessed portion so as not to protrude outward from the side surface. In the manufacturing method of the lens unit configured by stacking the resin lenses, the steps of stacking the resin lenses by shifting the position of the gate mark between adjacent ones around the optical axis, and applying an adhesive in the recess And a procedure for adhering the resin lenses to each other.

  In the present invention, the position of the gate mark between adjacent ones is shifted around the optical axis so that the respective resin lenses are overlapped, and the respective resin lenses are bonded to each other by the adhesive applied in the recess. Even when they are bonded to each other, the adhesive does not protrude from the side surface of each resin lens. And since an adhesive agent can be apply | coated thickly by the part of the depth of a recessed part, sufficient adhesive strength can also be acquired.

It is a perspective view which shows the structure of a lens unit. It is the front view and side view which show the structure of a lens unit. It is sectional drawing which shows the shape of each resin lens. It is sectional drawing which shows the state which accumulated each resin lens. It is explanatory drawing which shows that the adhesive agent is provided on both sides on both sides of the gate mark. It is a front view which shows the shape of the resin lens corresponding to a horizontally long aspect ratio.

  As shown in FIG. 1, the lens unit 2 includes first to fourth resin lenses 10 to 13. For each of the resin lenses 10 to 13, a known light-transmitting resin material such as plastic or acrylic is used. And each resin lens 10-13 is formed in the disk shape which has a substantially the same diameter by shape | molding such resin material by metal mold | die molding, such as an injection molding method. The lens unit 2 is configured as one lens in which the resin lenses 10 to 13 are integrated by superimposing these resin lenses 10 to 13 in the optical axis direction and bonding them to each other.

  As shown in FIGS. 1 and 2, the first resin lens 10 is provided with a recess 14 formed so as to cut out a part of the side surface 10a. The concave portion 14 is a so-called D-cut concave portion, and is formed in a shape in which a side surface 10a which is a circumferential surface of the disk-shaped first resin lens 10 is cut out by a plane substantially parallel to the optical axis. Accordingly, the recess 14 is a recess that is cut out continuously from the front side end to the rear side end of the side surface 10a. The second resin lens 11, the third resin lens 12, and the fourth resin lens 13 also have recesses 15, 16, and 17 formed on the side surfaces 11a, 12a, and 13a in the same manner as the recess 14 of the first resin lens 10, respectively. Is provided.

  Moreover, each resin lens 10-13 has the gate traces 20-23 in the recessed parts 14-17, respectively. The gate marks 20 to 23 are formed in a substantially rectangular protrusion shape whose width is narrower than the recesses 14 to 17 and whose height is adjusted so as not to protrude outward from the side surfaces 10a to 13a. Located near the center. The length of the gate marks 20 to 23 in the optical axis direction is substantially the same as the width of the side surfaces 10a to 13a, and both ends of the gate marks 20 to 23 are substantially the same as the front and rear surfaces of the resin lenses 10 to 13, respectively. It is the same.

  As shown in FIG. 3, which is a cross-sectional view taken along the line Aa in FIG. 2, the first resin lens 10 has an annular plane portion that is a plane substantially orthogonal to the optical axis in the vicinity of the outer periphery of the front and rear surfaces. 10b and 10c are formed. The second resin lens 11, the third resin lens 12, and the fourth resin lens 13 are also formed with flat portions 11 b, 11 c, 12 b, 12 c, 13 b, and 13 c similar to the first resin lens 10, respectively. These flat portions 10b, 10c, 11b, 11c, 12b, 12c, 13b, and 13c are so-called edge surfaces.

  As shown in FIG. 4, the 1st resin lens 10 and the 2nd resin lens 11 are piled up, making the plane part 10c and the plane part 11b contact, respectively. Similarly, the second resin lens 11 and the third resin lens 12 are overlapped with the flat surface portion 11c and the flat surface portion 12b contacting each other, and the third resin lens 12 and the fourth resin lens 13 are respectively flat surface portions. 12c and the flat surface portion 13b are brought into contact with each other and overlapped. Further, the resin lenses 10 to 13 are arranged so that the positions of the gate marks 20 to 23 of the adjacent ones are shifted by approximately 180 degrees around the optical axis, that is, so as to be substantially symmetric with respect to the optical axis. Overlapping is performed by shifting the position of 20-23. The flat portion 10b on the front surface side of the first resin lens 10 that does not come into contact with other lenses and the flat surface portion 13c on the rear surface side of the fourth resin lens 13 are not necessarily formed.

  The depths of the recesses 14 to 17 are shallower than the radial widths of the plane portions 10b, 10c, 11b, 11c, 12b, 12c, 13b, and 13c, and the portions of the effective radii of the resin lenses 10 to 13 are included. It is formed only in each of the flat portions 10b, 10c, 11b, 11c, 12b, 12c, 13b, and 13c. And since the recessed parts 14-17 are each notched from the edge part of the front side of the side surface 10a, 11a, 12a, 13a to the edge part of the rear surface side, respectively, as mentioned above, each resin lens 10-13 Are overlapped, both ends of the concave portions 14 to 17 in the optical axis direction also come into contact with the flat portions 10c, 11b, 11c, 12b, 12c, and 13b of the adjacent resin lenses 10 to 13, respectively.

  The gate trace 20 of the first resin lens 10 is formed so that both ends in the optical axis direction are substantially flush with the flat portions 10b and 10c. The other gate traces 21 to 23 are configured in the same manner as the gate trace 20 of the first resin lens 10. Accordingly, when the resin lenses 10 to 13 are overlapped as described above, both ends of the gate marks 21 to 23 in the optical axis direction are also flat portions 10c, 11b, 11c, 12b, and 12c of the adjacent resin lenses 10 to 13, respectively. , 13b.

  Each resin lens 10 in a state of being overlapped as described above is formed on each of the contact portions of the resin lenses 10-13 adjacent to the concave portions 14-17 with the flat portions 10c, 11b, 11c, 12b, 12c, 13b. An adhesive 25 for adhering 13 is applied. Each adhesive 25 is applied in the recesses 14 to 17 with a thickness corresponding to the depth of the recesses 14 to 17 so as not to protrude outward from the side surfaces 10a, 11a, 12a, and 13a. Further, since the gate marks 20 to 23 arranged in the vicinity of the center of the recesses 14 to 17 are also in contact with the flat portions 10c, 11b, 11c, 12b, 12c, and 13b, as shown in FIG. It is applied on both sides of the gate marks 20-23. For each adhesive 25, for example, an ultraviolet curable adhesive is used. Further, in FIGS. 1 and 2, the illustration of the adhesives 25 is omitted for the sake of convenience in consideration of easy viewing of the drawings.

  In this way, the resin lenses 10 to 13 are bonded to each other by the adhesives 25 to bring the flat portions 10c, 11b, 11c, 12b, 12c, and 13b into contact with each other and the gates of adjacent ones. The positions of the marks 20 to 23 are integrally held in a state where the marks 20 to 23 are overlapped by being shifted by about 180 degrees around the optical axis. At this time, since each adhesive 25 does not protrude outward from the side surfaces 10a, 11a, 12a, and 13a, each adhesive 25 interferes with assembling into the lens frame, and each adhesive 25 becomes a lens frame. In contrast, point contact is not a factor in optical axis misalignment. Furthermore, since each adhesive agent 25 can be thickly applied by the depth of the recesses 14 to 17, even when each adhesive agent 25 is prevented from protruding outward from the side surfaces 10a, 11a, 12a, 13a. Each adhesive 25 does not become thin, and sufficient adhesive strength can be obtained.

  When the resin lenses 10 to 13 are bonded, for example, a cylindrical shape having an inner diameter substantially the same as the outer diameter of the resin lenses 10 to 13 and openings that expose the concave portions 14 to 17 are provided on the side surfaces. It is preferable to use a prepared jig. With the resin lenses 10 to 13 being inserted into the jig, the resin lenses 10 to 13 are bonded by allowing the adhesive injectors to access the recesses 14 to 17 from the side openings. If it carries out like this, the optical axis of each resin lens 10-13 can be match | combined easily, and the efficiency of adhesion | attachment operation | work can be improved.

  In the above-described embodiment, the shift amount around the optical axis of the gate marks 20 to 23 between the adjacent resin lenses 10 to 13 is set to approximately 180 degrees, but the shift amount is not limited to this and may be an arbitrary angle. . Moreover, in the said embodiment, although the deviation | shift amount between each resin lens 10-13 was unified at about 180 degree | times, for example, the deviation | shift amount between the 1st resin lens 10 and the 2nd resin lens 11 is 90 degree | times, 2nd. The shift amount between the resin lenses 10 to 13 is such that the shift amount between the resin lens 11 and the third resin lens 12 is 120 degrees, and the shift amount between the third resin lens 12 and the fourth resin lens 13 is 180 degrees. May be changed as appropriate. However, since the holding between the adjacent resin lenses is held in a cantilever manner when the deviation amount is small, the deviation amount is preferably 90 degrees or more, and is appropriately held on both sides between the adjacent resin lenses. 180 degrees is most suitable.

  In the above embodiment, both ends of the gate marks 20 to 23 in the optical axis direction are in contact with the flat portions 10c, 11b, 11c, 12b, 12c, and 13b of the adjacent resin lenses 10 to 13, but the gate marks 20-23 may not necessarily be in contact with the plane portions 10c, 11b, 11c, 12b, 12c, 13b. In this case, it is preferable to apply the adhesive 25 also to the gaps between the gate marks 20 to 23 and the flat portions 10c, 11b, 11c, 12b, 12c, and 13b.

  In the said embodiment, although each disk-shaped resin lens 10-13 was shown, the shape of each resin lens 10-13 is not limited to this, Arbitrary shapes may be sufficient. For example, in recent years, many projectors that support a 16: 9 landscape aspect ratio have appeared, and in this case, the upper and lower parts of the disk-shaped lens are wasted. Therefore, as in the resin lens 30 shown in FIG. 6, the upper and lower portions of the disk-shaped lens may be cut according to the aspect ratio of 16: 9. In this case, the arc-shaped side surface 30a that is symmetric with the concave portion 31 and the gate trace 32, that is, the same direction as the concave portion 31 and the gate trace 32 when the two resin lenses 30 are rotated and rotated approximately 180 degrees. The side surface 30a that faces the target surface is the target side surface, and the concave portion 31 and the gate mark 32 may be formed so that the gate mark 32 and the adhesive 25 do not protrude outside the side surface 30a.

  In the said embodiment, although each resin lens 10-13 was made into the disk shape which has substantially the same diameter, ie, the cross-sectional shape of each resin lens 10-13 was substantially the same, the cross-sectional shape of each resin lens 10-13 is It is not necessarily the same. However, if each of the resin lenses 10 to 13 has a different cross-sectional shape, the adhesive 25 can be provided only on the side having a small area, and there is a concern that the holding of the resin lenses 10 to 13 may be cantilevered. Therefore, it is preferable that the cross-sectional shapes of the resin lenses 10 to 13 are substantially the same.

  In the above embodiment, the lens unit 2 including the four resin lenses 10 to 13 is shown. However, the number of resin lenses constituting the lens unit 2 may be two or three, or five or more. .

2 Lens unit 10 First resin lens 10a Side surface 10b, 10c Plane portion 11 Second resin lens 11a Side surface 11b, 11c Plane portion 12 Third resin lens 12a Side surface 12b, 12c Plane portion 13 Fourth resin lens 13a Side surface 13b, 13c Plane portion Part 14-17 Concave part 20-23 Gate trace 25 Adhesive

Claims (6)

A plurality of resin lenses having a concave portion formed so as to cut out a part of the side surface and having a gate mark that is a trace at the time of molding the mold are stacked on the concave portion so as not to protrude outward from the side surface. In the configured lens unit,
A lens unit characterized in that the positions of the gate marks of adjacent ones are shifted around the optical axis, the resin lenses are stacked, and the resin lenses are bonded to each other with an adhesive applied in the recess.   2. The lens unit according to claim 1, wherein a deviation amount of the gate mark between the adjacent resin lenses around the optical axis is approximately 180 degrees. Each of the resin lenses is formed with an annular plane portion that is a plane substantially orthogonal to the optical axis in the vicinity of the outer periphery of the front and rear surfaces,
Each of the resin lenses is overlapped by bringing these flat portions into contact with each other,
3. The lens unit according to claim 1, wherein the concave portion is formed shallower than a width of the planar portion and contacts the planar portion of the adjacent resin lens. Each resin lens is formed in a disc shape,
The lens unit according to any one of claims 1 to 3, wherein the concave portion is formed in a shape in which the side surface that is a circumferential surface is cut out by a plane substantially parallel to the optical axis.   The gate mark is formed in a protrusion shape whose height is adjusted so as to be narrower than the width of the recess and not to protrude outward from the side surface, and is disposed near the center of the recess. The lens unit according to any one of claims 1 to 4. A plurality of resin lenses having a concave portion formed so as to cut out a part of the side surface and having a gate mark that is a trace at the time of molding the mold are stacked on the concave portion so as not to protrude outward from the side surface. In the manufacturing method of the configured lens unit,
The procedure of overlapping each resin lens by shifting the position of the gate mark between adjacent ones around the optical axis;
A method of manufacturing a lens unit, comprising: adhering each resin lens to each other by applying an adhesive in the recess.

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