An embodiment of the present invention will now be described through reference to the drawings.
The lens structure 10 applied to the optical device 1 (see
The lens structure 10 is formed by using a synthetic resin to integrally injection mold the lens portion 11 and the skirt portion 12. This injection molding can be carried out by injecting a synthetic resin such as an acrylic resin from a molding gate FG into a molding gate receiving portion 14. The molding gate receiving portion 14 is provided at an end of the skirt portion 12, and is configured to facilitate injection molding. In addition to an acrylic resin, the resin usable here can be a polycarbonate resin or the like.
The molding gate receiving portion 14 is similar to the skirt portion 12 in that it has two plane faces disposed parallel to a direction intersecting the optical axis direction of the lens portion 11. In other words, the molding gate receiving portion 14 can be formed at an end of the skirt portion 12 in the same manner as the skirt portion 12, which means that the structure of the mold used to form the molding gate receiving portion 14 can be simplified.
If the lens portion 11 has a small curvature and the lens diameter φ is large, then generally the thickness t2 of the edge 11t will be less, and as a result the thickness of the skirt portion 12 will also be less, and there will be greater resistance to the flow of the synthetic resin in injection molding.
According to this embodiment, however, since the molding gate receiving portion 14 is provided which has a thickness t3 that is greater than the thickness t2 of the edge 11t, it is possible to reduce resistance to the flow of the synthetic resin (molding resin) supplied from the molding gate FG (molding gate receiving portion 14) to the skirt portion 12 and the lens portion 11 during injection molding.
In other words, since a good flow of the molding resin to the skirt portion 12 and the lens portion 11 is ensured, and the resin will flow in more smoothly and stably, there is no loss of fluidity of the synthetic resin, the skirt portion and lens portion can be filled and molded smoothly and with good fluidity, stable lens portion 11 in which no sink marks or cracks occur can be formed at high precision, and stable injection molding can be performed at a high yield.
Because the thickness t2 of the edge 11t is less than the thickness t3 of the molding gate receiving portion 14, as mentioned above, it is possible to obtain a lens structure 10 having a lens portion 11 with a small curvature, a large lens diameter φ, and high precision. Also, the thickness t3 of the molding gate receiving portion 14 is designed to be less than the thickness t1 of the lens portion 11 in order to prevent the formation of sink marks on the lens portion 11. In other words, the relationship is such that the thickness t3 of the molding gate receiving portion 14<the thickness t1 of the lens portion 11.
When the lens diameter φ of the lens portion 11 was 10 mm, for example, and the thickness t1 of the lens portion 11 was from 3 to 5 mm, the thickness t3 of the molding gate receiving portion 14 could be set to about 2 to 3 mm, and the thickness t2 of the edge 11t could be set to 0.2 to 0.5 mm. When the thickness t2 of the edge 11t was less than 0.2 mm, there was more resistance to the resin flow and yield dropped off sharply. Accordingly, taking some extra yield into account, the thickness t2 of the edge 11t preferably is 0.3 to 0.5 mm.
It is undesirable for the thickness t2 of the edge 11t to be greater than 0.5 mm because this will hamper efforts at reducing the size of the lens structure 10. That is, by specifying the thickness t2 of the edge 11t, the desired lens structure 10 can be formed at a good yield and high precision.
The molding gate FG is disposed with respect to the molding gate receiving portion 14 so that its position is higher with respect to a plane as shown in cross section (
As mentioned above, a constitution which maintains the relationship: the thickness t2 of the edge 11t<the thickness t3 of the molding gate receiving portion 14<the thickness t1 of the lens portion 11 provides a lens portion 11 that has a smaller curvature, is thicker, and has a broader surface area, and short focus and high numerical aperture characteristics can be achieved. Also, because the lens structure 10 (lens portion 11) can be formed at high precision with fewer sink marks, cracks, and so forth, it is possible to form the lens portion 11 at high precision even when the lens portion 11 has an aspherical shape. Using an aspherical shape affords a compact and lightweight optical device 1 with no aberration.
The optical device 1 is equipped with the lens structure 10 in a housing 20 that is open at the rear. The lens structure 10 is constituted, for example, by a light emission lens structure 10e and a light reception lens structure 10r (
The lens structure 10 is shown as being separate from the housing 20, but the lens structure 10 and the housing 20 can be formed integrally by two-color molding, for example. Integral molding allows the assembly process of the optical device 1 to be simplified and its precision increased, and this affords a higher manufacturing yield and a reduction in manufacturing costs.
A printed substrate 21, in which a semiconductor light-emitting element 22e and a semiconductor light-receiving element 22r serving as optical semiconductor elements 22 are individually mounted, separate from one another, is inserted from the rear face of the housing 20, across from the lens structure 10. In other words, the semiconductor light-emitting element 22e and semiconductor light-receiving element 22r serving as the optical semiconductor elements are mounted on the surface of the printed substrate 21 (the side across from the lens structure 10) that is inserted inside the housing 20 (
A suitable wiring pattern is formed on the printed substrate 21, and the semiconductor light-emitting element 22e, the semiconductor light-receiving element 22r, and other circuit parts are suitably mounted as chip components. Also, the light emission lens structure 10e is disposed across from the semiconductor light-emitting element 22e, and the light reception lens structure 10r is disposed across from the semiconductor light-receiving element 22r.
A substrate fixing screw hole 21h, for inserting a screw that fixes the printed substrate 21 to the housing 20, is formed in the middle of the printed substrate 21. A substrate fixing column 20c into which is threaded the screw that fixes the printed substrate 21 to the housing 20 is erected (formed) in the middle of the inner bottom face of the housing 20. A screw hole 20h into which the screw is inserted is formed in the substrate fixing column 20c, corresponding to the substrate fixing screw hole 21h. This configuration makes it possible to screw and fix the printed substrate 21 to the housing 20 (the substrate fixing column 20c), and allows the optical semiconductor elements 22 and the lens structure 10 to be easily positioned and fixed across from each other.
The printed substrate 21 is configured so that it abuts a columnar anti-rotation portion 25 formed from the open side of an inner side face (inner wall 20w) of the housing 20 toward the inner bottom face (
A plurality of the anti-rotation portions 25 are disposed at opposing locations on the inner wall 20w, such that they lie along the longitudinal side of the printed substrate 21, and are formed so as to protrude in the form of semicircular columns from the inner wall 20w. This configuration ensures enough space between the printed substrate 21 and the housing 20, so the printed substrate 21 can be inserted easily and reliably into the housing 20, which improves work efficiency. The anti-rotation portion 25 may have a suitably curvature, and does not need to have a true semicircular shape.
Also, even if the printed substrate 21 is larger than the specified size due to nominal error in the external dimensions, when the printed substrate 21 is inserted into the housing 20, the printed substrate 21 can be easily and precisely inserted in a state in which the anti-rotation portions 25 in the form of semicircular columns shave the edges of the printed substrate 21, so the space between the printed substrate 21 and the anti-rotation portions 25 can be made very small (minimized), ensuring accurately positioning precision.
The substrate fixing column 20c is supported by a plurality of reinforcing plates 26 (reinforcing plates 26a, 26b, 26c, and 26d; hereinafter, when there is no need to distinguish the reinforcing plates 26a, 26b, 26c, and 26d from one another, they will merely be referred to as the reinforcing plates 26). Using the plurality of reinforcing plates 26 ensures that the substrate fixing column 20c will be supported reliably and securely, with enough strength, and securely fixes the printed substrate 21. Therefore, an optical device 1 of high reliability can be obtained.
The reinforcing plates 26 are erected on the inner bottom face just as is the substrate fixing column 20c, and link and integrate the inner wall 20w and the substrate fixing column 20c together. If spaces are provided between the plurality of reinforcing plates 26 (between the reinforcing plate 26a and the reinforcing plate 26b, and between the reinforcing plate 26c and the reinforcing plate 26d) to create thinned portions 26s, it will be possible to obtain a housing 20 in which distortion does not occur by preventing the occurrence of sink marks in the molding resin around the middle of the housing 20 (around the substrate fixing column 20c and the reinforcing plates 26), so an optical device 1 can be obtained at a higher yield.
The reinforcing plates 26 are disposed between the semiconductor light-emitting element 22e and the semiconductor light-receiving element 22r. Therefore, it is possible to prevent the occurrence of an optical path by which light from the semiconductor light-emitting element 22e reaches the semiconductor light-receiving element 22r directly, without passing through the lens structure 10, and to block any other stray light, which enhances the optical characteristics of the optical device 1.
Also, a light blocking plate 27 is disposed, in addition to the reinforcing plates 26, between the semiconductor light-emitting element 22e and the semiconductor light-receiving element 22r. Therefore, stray light can be eliminated more effectively, and the optical characteristics of the optical device 1 can be further enhanced. It is also possible to provide additional reinforcing plates between the reinforcing plates 26 and the light blocking plate 27.
The lens structure 10 is inserted to the inner bottom face of the housing 20, with the skirt portion 12 abutting the inner wall 20w, and is positioned and fixed. The semiconductor light-emitting element 22e is correspondingly disposed at a lens structure 10e, and the semiconductor light-receiving element 22r is correspondingly disposed at a lens structure 10r. The printed substrate 21 is fixed by being fastened with a screw 21v to the substrate fixing column 20c.
Because the anti-rotation portion 25 has a slanted portion 25s at its end (the side where the printed substrate 21 is inserted), the insertion opening is larger when the printed substrate 21 is inserted, and the printed substrate 21 can be easily and reliably inserted into the housing 20, which makes the work easier.
By forming the anti-rotation portion 25, the reinforcing plates 26, and the light blocking plate 27 integrally with the housing 20 using a suitable synthetic resin, it is possible to simplify the manufacturing process and reduce the manufacturing cost (assembly cost).
As discussed above, the optical device 1 has short focus and high numerical aperture characteristics, so a more compact size and higher resolution can be achieved, allowing the optical device 1 to be applied to a range-finding device, for example. A case in which the optical device 1 is used as a range-finding device that operates by optical triangulation will be described.
For example, a light beam BL emitted from a semiconductor light-emitting element 22e made up of light emitting diodes (LEDs), for example, is converged on the light emission lens structure 10e (lens portion 11), and is irradiated to a ranging object OBJ. The light beam BL irradiated to the ranging object OBJ is diffused and reflected by the surface of the ranging object OBJ, then enters the light reception lens structure 10r (lens portion 11) as reflected light BLR, is converged, and an image is formed on a semiconductor light-receiving element 22r made up of position detection elements (PSDs).
A triangle TA1 made up of the light beam BL and the reflected light BLR on the outside of the optical device 1, and a triangle TA2 made up of the light reception lens structure 10r and the semiconductor light-receiving element 22r in the optical device 1 are similar.
Here, the lens spacing distance Ler between the light emission lens structure 10e and the light reception lens structure 10r, and the focal length Lf of the light reception lens structure 10r are determined by the structure of the optical device 1. Therefore, by measuring the displacement distance Ls of the light spot converged on the semiconductor light-receiving element 22r (the deviation from a reference position), it is possible to obtain a measured distance La from the optical device 1 to the ranging object OBJ.
That is, the measured distance La can be obtained as (focal length Lf lens spacing distance Ler/displacement distance Ls) from the relationship of (the measured distance La from the optical device 1 to the ranging object OBJ)/(the lens spacing distance Ler between the light emission lens structure 10e and the light reception lens structure 10r)=(the focal length Lf of the light reception lens structure 10r)/(the displacement distance Ls of the light spot converged on the semiconductor light-receiving element 22r).
Because of manufacturing limitations, short focus and high numerical aperture characteristics could not be attained in the lens structure 10. When the lens structure 10 according to this embodiment is applied to the optical device 1, however, the device can be made smaller, and an optical triangulation range-finding device capable of measuring long distances can be obtained. That is, by applying the optical device 1 according to this embodiment to an optical triangulation range-finding device, it is possible to provide a compact high performance range-finding device that can measure long distances.
Because it is possible to measure the distance to a screen by installing the above-mentioned range-finding device (optical device 1) as an electronic device such as a projector, a projector can be obtained that has higher functionality such as auto-focus and is more compact through more efficient use of space.
Also, by installing this in an electronic device such as a lighting device, it is possible to detect the distance to (position of) a person over a wide range of distances, and thereby control the lighting device to turn on/off. Also, by varying the brightness according to the distance to a person, an auto-switch sensor that is more compact and has higher functionality can be obtained.
Also, since it is possible to manufacture a short-focus lens, smaller size and higher functionality can be achieved not only in the above-mentioned range-finding devices, but also in precision photointerrupters and other such electronic devices.
The present invention can be embodied in a variety of other forms without departing from the main characteristics or essence thereof. Accordingly, the embodiments given above are in all respects nothing more than examples, and should not be interpreted to be limiting in nature. The scope of the present invention is as indicated by the Claims, and is in no way restricted to the text of this Specification. Furthermore, changes and modifications falling within an equivalent scope of the Claims are all within the scope of the present invention.
Number | Date | Country | Kind |
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2006-199704 | Jul 2006 | JP | national |