JP4444577B2 - Small plastic lens - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a small plastic lens having an outer diameter of 12 mm or less, and more particularly to a small plastic lens useful for a personal computer or a mobile phone having a camera function.
[0002]
[Prior art]
In a conventional plastic lens, a plastic material is injected into a cavity of an injection mold, and a molded product is taken out after cooling. Therefore, it was necessary to provide a draft to the mold used therefor so that the molded product can be easily taken out of the mold (for example, see Non-Patent Document 1).
[0003]
FIG. 4 shows a conventional injection mold in which a cavity 12 is formed between a mold plate 10 and a mold plate 11 and a draft 13 is formed in a part of the mold plate 10 where the cavity 12 is formed. . Further, nested molds 10A and 11A are provided at the lens surface molding locations. A molded product (lens) 100 injection-molded with this mold is assembled in the lens barrel 20 as shown in FIG. The lens barrel 20 has a bottom surface 20A formed at a portion protruding inward, and has an inner peripheral surface 20B orthogonal to or substantially orthogonal to the bottom surface 20A, and the molded product 100 is assembled to the lens barrel 20. In this assembly, the molded product 100 is brought into contact with and adhered to the bottom surface 20A and the inner peripheral surface 20B. The molded product 100 has a tapered surface 100A molded at the portion of the draft angle 13 of the template 10, so that the contact area between the bottom portion 100C and the bottom surface 20A of the flange 100B is reduced. In the example shown in FIG. 5, the width _{d 1} of the bottom 100C is less than half the width _{d 2} of the bottom surface 20A. A portion ahead of the tapered surface 100A forms a straight surface 100D, and most of the straight surface 100D is in contact with the inner peripheral surface 20B. The length _{l 2} of the length _{l 1} and the tapered surface 100A of the straight surface 100D, there as substantially the same.
[0004]
[Non-Patent Document 1]
“Introduction to Plastic Molding” written by Masatoshi Tsuji and Masanobu Motoyoshi, published by Nikkan Kogyo Shimbun on June 10, 1998, P298-P299
[0005]
[Problems to be solved by the invention]
If the size of the injection molded product as described above is such that the lens outer diameter R (see FIG. 5) exceeds 20 mm, for example, the taper surface 100A of the flange 100B can be molded, but the overall diameter is 12 mm. for the is small plastic lens or less, for example when the diameter (R) 10 mm, a width _{d 1} of the bottom 100C is becomes about 0.1 to 0.2 mm. In plastic lenses used for mobile phones and the like, not only miniaturization of the lens itself but also miniaturization of the lens barrel is required. For this purpose, the flange 100B must be made to have a minimum size. If the width _{d 1} of the flange bottom 100C and 0.1~0.2mm as described above, very difficult thing to process mold (template 10) in the draft 13 (1 ° to 5 °) Met. Further, even if such draft 13 can be processed and formed into the template 10, the plastic material hardly flows into the draft 13 of the template 10 at the time of injection, and an unfilled portion is generated. There was also a fear. Further, even if able to mold the lens substantially as designed, since the receiving surface margin of the lens in the lens barrel 100 (the bottom surface 20A) _{d 2} is about 0.2 to 0.6 mm, a bottom portion 100C and the bottom surface 20A of the lens If the plastic material does not sufficiently flow into the tapered portion, when the lens is assembled to the lens barrel 20, the lens will not be large. There is a risk that the optical performance may not be obtained due to tilting.
[0006]
Accordingly, the present invention provides a small plastic lens that facilitates the processing of a mold for molding, has high dimensional accuracy of the molded product, prevents tilting when the lens barrel is assembled, and obtains predetermined optical characteristics. With the goal.
[0007]
[Means for Solving the Problems]
To achieve the above object, the present invention provides a bottom portion of a flange that contacts the bottom surface of the lens barrel, and an outer peripheral surface and a flange of the flange that contact an inner peripheral surface of the lens barrel that is orthogonal or substantially orthogonal to the bottom surface of the lens barrel. and a inner lens surface, in a small plastic lens is injection-molded in the molding die, with contacting the whole and the entire bottom of the flange bottom surface of the barrel the entire surface, the bottom narrowing around from the bottom to the outer peripheral surface Conversely predetermined the entire outer peripheral surface of the long component is formed on the straight surface for totally surface contact with the inner peripheral surface of the barrel toward the side, the outer periphery of to the top of the previous flange from straight surface of the flange outer peripheral surface and The surface is formed on a tapered surface formed by a draft of a molding die so that the outer diameter gradually increases.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0009]
FIG. 1 shows a cross section of the upper half of a small plastic lens 1 according to the present invention assembled to a lens barrel 2. The lens barrel 2 has a bottom surface 2A serving as a receiving surface for the lens 1, and the bottom surface 2A. The lens barrel 2 has an inner peripheral surface 2B that is orthogonal or substantially orthogonal. The boundary between the bottom surface 2A and the inner peripheral surface 2B has a radius of curvature of 0.2 mm or less. In the lens 1, a lens barrel assembly flange 4 is formed on the outer periphery of the lens surface 3, and a bottom portion 4 </ b> A of the flange 4 contacts the previous bottom surface 2 </ b> A. The bottom surface 2A and the bottom portion 4A are in contact with each other on almost the entire surface. Further, the outer peripheral surface of the flange 4 is formed on the straight surface 4B on the inner peripheral surface 2B, and the straight surface 4B is in contact therewith. From the outer peripheral straight surface 4B, a tapered surface 4C is formed that gradually inclines in the direction in which the outer diameter increases. The gradient of the tapered surface 4C is about 1 ° to 5 °. The length of the straight surface 4B on the outer peripheral surface of the flange 4 is illustrated as l ₂ , and the length of the tapered surface 4C is illustrated as l ₁ . The length _{l 2} of the straight surface 4B in this embodiment was set to 1.8 mm. The diameter of the contact surface with the lens barrel 2 was 10 mm. The surface area d between the lens 1 and the lens barrel 2 was 0.25 mm.
[0010]
FIG. 2 shows an overall cross section of the lens 1 assembled to the lens barrel 2. The impact surface diameter of the lens 1 is indicated by the symbol R. The inner peripheral surface on the opening side of the lens barrel 2 is formed with a tapered portion 2C that matches the shape of the tapered surface 4C. The entire bottom surface 2A of the lens barrel 2 and the entire bottom portion 4A of the flange 4 are brought into almost complete contact, and the entire outer peripheral surface, that is, a predetermined length that goes from the bottom portion 4A to the outer peripheral surface and faces away from the bottom portion 4A. The surface 4B is in contact with the inner peripheral surface 2B of the lens barrel 2 almost entirely. Then, the outer peripheral surface from the straight surface 4B of the outer peripheral surface of the flange 4 is formed into a tapered surface 4C whose outer diameter gradually increases. The impact surface diameter R shown in FIG. 2 is 10 mm in this embodiment, but can be molded within a range of 2 mm as the minimum diameter and 12 mm as the maximum diameter. Preferably it is 2.5 mm-10 mm. Further, the impact surface cost d is preferably in the range of 0.25 to 0.60 mm in order to stabilize the lens assembly and ensure the optical characteristics.
[0011]
FIG. 3 shows a molding die for a small plastic lens according to the present invention. A cavity 7 is formed between the mold plate 5 and the mold plate 6, and a draft angle 8 is formed in the mold plate 5. . Further, telescopic molds 5A and 6A are provided at the lens surface molding points. In this cavity 7, the portion forming the bottom portion 4 </ b> A of the flange 4 is not tapered as in the conventional example. Conventionally, a draft is formed at this point (see FIG. 4), but in the injection mold of the present invention, a draft 8 is formed on the opposite side so that the diameter is increased. Accordingly, it is easy to process the draft 8 in the template 5, and since the tapered cavity portion is eliminated, the resin can be filled smoothly.
[0012]
It should be noted that the chamfering process (for example, about R0.2 mm) is performed on a portion where the bottom portion 4A of the flange intersects with the straight surface 4B to have a portion that is not in contact with the bottom surface 2A of the lens barrel and the inner peripheral surface 2B. Needless to say, it is included in the scope of the present invention.
[0013]
【The invention's effect】
As described above, according to the present invention, the bottom portion of the flange that contacts the bottom surface of the lens barrel, and the outer peripheral surface and flange of the flange that contact the inner peripheral surface of the lens barrel that is orthogonal or substantially orthogonal to the bottom surface of the lens barrel and a inner lens surface, in a small plastic lens is injection-molded in the molding die, with contacting the whole and the entire bottom of the flange bottom surface of the barrel the entire surface, the bottom narrowing around from the bottom to the outer peripheral surface Conversely predetermined the entire outer peripheral surface of the long component is formed on the straight surface for totally surface contact with the inner peripheral surface of the barrel toward the side, the outer periphery of to the top of the previous flange from straight surface of the flange outer peripheral surface and since a tapered surface gradually outer diameter surface is formed by draft of the mold so as to increase, processing of the molding die for molding the lens is also easy, and sneak plastic material Since Had points eliminated filled insufficient situation can also be prevented, the molded lens, it is possible to perform integration into the barrel accurately. In particular, this lens can be molded when the outer diameter is 2 mm to 12 mm or less, can be molded as designed, can be accurately assembled to the lens barrel, and has predetermined optical characteristics. You can also get
[Brief description of the drawings]
FIG. 1 is a partially enlarged sectional view showing a preferred embodiment of the present invention.
FIG. 2 is an overall cross-sectional view showing a state in which this lens is assembled in a lens barrel.
FIG. 3 is a cross-sectional view showing a mold for molding the lens of the present invention.
FIG. 4 is a cross-sectional view showing a conventional lens molding die.
FIG. 5 is a cross-sectional view showing a state in which a conventional lens is assembled in a lens barrel.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Lens 2 Lens barrel 2A Bottom surface 2B Inner peripheral surface 3 Lens surface 4 Flange 4A Bottom part 4B Straight surface 4C Tapered surface

Claims (4)

A molding die comprising a bottom portion of a flange that contacts the bottom surface of the lens barrel, an outer peripheral surface of the flange that contacts an inner peripheral surface of the lens barrel that is orthogonal or substantially orthogonal to the bottom surface of the lens barrel, and a lens surface inside the flange. In small plastic lenses that are injection molded in
A whole and the entire bottom of the flange bottom surface of the lens barrel with contacting the entire surface, the outer peripheral surface entire predetermined toward the side opposite to the bottom portion narrowing around the outer peripheral surface of the length fraction from the bottom on the inner peripheral surface of the barrel formed on the straight surface for totally surface contact,
A small plastic lens characterized in that the outer peripheral surface from the straight surface of the flange outer peripheral surface to the top of the previous flange is formed into a tapered surface formed by a draft of a molding die so that the outer diameter gradually increases. .   The small plastic lens according to claim 1, wherein an outer diameter is 2 mm to 12 mm or less.   The small plastic lens according to claim 1 or 2, wherein a width of a bottom surface of the flange is set to 0.25 to 0.60 mm.   The small plastic lens according to any one of claims 1 to 3, wherein a slope of the tapered surface is set to 1 ° to 5 °.

Images