JP2002202448A - Automatic focusing module and molding method of its lens and molding die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the non-defective rate of a product by preventing the faulty assembly of an automatic focusing module, which is a problem in the conventional constitution. SOLUTION: In this automatic focusing module consisting of the assembly of a plastics lens, a light shielding box and an automatic focusing IC, the upper surfaces of flange parts 1a overhanging to the left and right sides from the lens parts 1L and 1R of the plastics lens 1 are made flat surfaces. At the assembling time of the module, the flange parts are fit between lens supporting projections formed at four corners of the periphery of the light shielding box, and the lens 1 is superposed on the end face of the light shielding box and also the flange parts are pressed down by the pressing pawl of an assembly tool from the upside. In such a state, the position of the optical system is adjusted and then the lens and the light shielding box are bonded to assemble the module. Thus, the inclination of the assembly caused by the bite of the pressing pawl at the flange part with the adjustment of the position of the optical system is eliminated, so that the assembling accuracy and the range- finding accuracy of the module are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autofocus module applied to an autofocus distance measuring device such as an autofocus camera, and more particularly to a shape and a molding method of a plastic lens thereof and a molding die thereof.

[0002]

2. Description of the Related Art The autofocus module described above is well known, and its assembling structure includes a two-lens plastic lens 1, a light-shielding box 2, and an autofocus IC 3, as shown in FIGS. 5 (a) to 5 (c). It consists of assembly. Here, as shown in FIGS. 6A and 6B, the plastic lens 1 has a pair of left and right convex lens portions 1L, 1R and 1L, 1L.
Flange (edge) 1 that protrudes laterally from both ends of R
This is a molded product of a transparent resin made of a, and is molded using an injection mold 5 shown in FIG. This molding die 7 is a fixed die 5
a, movable die 5b, lens core 5 combined with movable die 5b
c, and a pair of left and right ejector pins 5d. After molding resin is injected into a cavity 5e defined between the fixed mold 5a, the movable mold 5b, and the core 5c to form the plastic lens 1 of FIG. When ejecting the lens 1 from the mold 5, the ejector pin 5d is operated with the mold 5 opened, and the upper surface of the flange of the lens 1 is pushed (when the lens is pushed by the ejector pin 5d, the lens There is a possibility that a trace of a pin may be formed on the surface of the mold, so that an ejector pin is applied to a flange portion detached from the lens portion to protrude.) The molded product is released from the mold 5. In this case, in the protruding method in which the flange portion 1a of the lens 1 is pushed by the ejector pin 5d as described above, a large force is locally applied to the flange portion 1a. As shown in the figure, the upper surface side of the flange portion 1a is formed into a tapered (gradient angle α) surface, and the portion of the flange portion 1a where the protruding pin contacts is thickened to reinforce.

On the other hand, a light-shielding box 2 is provided with an auto-focus IC for shielding light from the surroundings, and
3 is a black resin molded product that serves to guide light to the photosensor array 3. A lens holding projection 2 a is formed upright at the periphery of the end surface on which the lens 1 is mounted. Note that the autofocus IC 3 is superposed and adhered to the lower surface side of the light-shielding box 2. Reference numeral 4 denotes an external lead-out terminal of the IC 3.

In the autofocus module having such a configuration, the plastic lens 1 is assembled in the following procedure. That is, the plastic lens 1 is mounted on the upper end side of the light-shielding box 2 on which the autofocus IC 3 is mounted,
In this state, the optical system is aligned so that the optical axes of the lens portions 1L and 1R of the lens 1 and the position of the photosensor array of the autofocus IC 3 are correctly aligned.
The flange 1a of the plastic lens 1 and the light-shielding box 2 are fixed with an adhesive.

Here, the assembling process of mounting the lens 1 in the light-shielding box 2 will be described in detail. The flange 1a of the lens 1 is fitted between the protrusions 2a formed on the peripheral edge of the light-shielding box 2 to mount the lens 1. The lens 1 is placed from above, and a pair of right and left holding claws 6a provided on an assembling device (jig) 6 as shown in FIG. In the pressed state, the position of the optical system is adjusted to position the lens 1, and an instant adhesive or the like is dropped on the periphery of the flange portion 1 a of the lens 1 to adhere to the light-shielding box 2. After the module is assembled, a transparent filler is injected into the light-shielding box 2 to seal and protect the sensor portion of the autofocus IC 3.

[0006]

However, the above-described assembly of the autofocus module has a problem that the non-defective product ratio is reduced, such as a decrease in distance measurement accuracy due to a defective assembly. As a result of the investigation, it was found that the cause of the assembly failure was as follows. That is, in the step of assembling the plastic lens 1 reinforced with a tapered upper surface of the flange portion 1a as shown in FIG. 6 to the light-shielding box 2, as described with reference to FIG. Is pressed against the upper surface of the flange portion 1a and pressed down from above. When the position of the optical system is adjusted and bonded in this state, the edge of the pressing claw 6a bites into the tapered surface of the flange portion 1a and the attitude of the assembly is slightly inclined. . For this reason, in the module assembly, the inclination (tilt angle θ) of the optical system remains as it is as shown in FIG. 8B, and an image height error occurs in the autofocus IC due to the assembly failure, and the distance measurement accuracy of the module is reduced. Lower.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to solve the above-mentioned problems and to prevent defective assembly which has been a problem in the conventional configuration and to improve the non-defective product rate. It is an object of the present invention to provide an autofocus module, a molding method and a molding die for the lens.

[0008]

According to the present invention, there is provided an autofocus module comprising an assembly of a plastic lens, a light-shielding box, and an autofocus IC. It has a flange part that protrudes laterally from both left and right ends, fits this flange part between lens supporting protrusions formed on the peripheral part of the light shielding box, overlaps the lens on the end face of the light shielding box, and assembles the flange. When the optical system is aligned and bonded while being held down by the holding claws of the jig and assembled, (1) The upper surface of the flange portion of the plastic lens is made a horizontal flat surface. On the end face of the light-shielding box, and in this state, use the assembly jig to align the optical system and It shall assemble I (claim 1).

According to the above configuration, even if the position of the optical system is adjusted in the module assembling step with the left and right flanges held down by the holding claws of the assembly jig, the edges of the holding claws bite into the flanges. The assembling attitude is not tilted, thereby preventing defective assembly and increasing the product non-defective rate of the autofocus module. (2) Further, according to the lens molding method of the present invention, (1)
The plastic lens of (1) is injection-molded, and when the lens is protruded from the molding die after molding, the surface area of the lens portion is pressed to be released from the mold (claim 2).

By adopting this lens forming method, it is not necessary to press the flange portion with the protruding pin when releasing the lens. Therefore, there is no need to reinforce the flange portion with a taper. (3) Further, according to the present invention, the molding die used in the lens molding method of the above item (2) comprises a fixed type, a movable type and an ejector lens core combined with a movable type, and a movable type cavity. As for the surface, a portion corresponding to the upper surface of the flange portion of the lens is horizontal, and when the injection molded lens is protruded from the mold, the lens molded product is released from the mold by the operation of pushing out the core. 3).

By using this molding die, the conventional protruding pins can be omitted, and the entire surface of the lens portion is pushed out by the lens portion insert when the lens molded product is released from the die. Therefore, the molded product of the lens can be released from the mold without leaving a trace on the lens surface.

[0012]

FIG. 1 is a block diagram showing an embodiment of the present invention.
4 to FIG. In the drawings of the embodiment, the same members as those in FIGS. 5 to 7 are denoted by the same reference numerals, and description thereof will be omitted. That is, the assembling structure of the autofocus module is the same as that of FIG. 5, but the plastic lens 1 to be mounted on the module is tapered on the upper surface of the flange portion 1a as shown in FIGS. (Fig. 6
Reference), and is formed on a flat surface parallel to the lower surface.

In the assembling step of placing the plastic lens 1 on the upper surface of the light-shielding box 2 and bonding the same, an assembling apparatus 6 similar to that shown in FIG. After the alignment of the optical system is performed in a state where the optical system is pressed against the upper surface, the flange portion 1a is fixed to the end surface of the light shielding box 2 with an adhesive. In this case,
Since the upper surface of the flange portion 1a is a flat surface, the optical system does not tilt slightly due to the pressing claw 6a biting into the flange surface, etc., resulting in a defective assembly which has been a problem in the conventional module assembly, and It is possible to prevent a decrease in the distance measurement accuracy of the module to be used.

FIG. 2 shows the plastic lens 1 shown in FIG.
FIG. 3 is a structural view of a molding die for manufacturing a mold. As shown in the figure, a molding die 5 is a fixed die 5a, a movable die 5b, and a movable lens core (cavity block) combined with the movable die 5b and also serving as an ejector. 5c, and the cavity surface of the movable mold 5b has a horizontal portion at a portion corresponding to the upper surface of the flange 1a of the plastic lens 1, and has a structure in which the projecting pin 5d in a conventional mold (see FIG. 7) is omitted. Become.

When the mold 5 is opened after the casting resin for the lens is injected into the cavity 5e in the molding process of the lens 1 and molded and cured, the lens 1 shown in FIG.
b, separate from the fixed mold 5a together with the lens core 5c.
Next, in the projecting step of releasing the formed product of the lens 1 from the mold 5, the lens portion core 5c is pushed out by a ram operation as an ejector, and the entire surface of the lens portions 1L and 1R is pressed to be released from the movable mold 5b.

By projecting a lens molded product from the mold using the lens core 5c as an ejector without using a projection pin, there is no possibility that traces will be formed on the surface of the lens portion, and a force is applied to the flange portion 1a. It can be released without any problems. This eliminates the need for a conventional tapered reinforcement for the flange portion 1a. Figures 3 and 4
FIG. 1 shows a structural diagram of a double-sided plastic lens having both surfaces of a lens portion as lens surfaces as an application example of the present invention, and a mold for molding the same. The flange portion 1a of the lens 1 is the same as in FIG. The upper and lower surfaces are horizontal flat surfaces. On the other hand, the mold 5 has a structure in which a lens core 5f corresponding to the lens surface on the lower surface side is combined with a fixed mold 5a, and a lens molded product using the lens core 5c combined with a movable mold 5b as an ejector as in FIG. To perform the protrusion operation. Note that the present invention is not limited to the illustrated embodiment described above,
The same can be applied to plastic lenses having different shapes.

[0017]

As described above, according to the present invention, the following effects can be obtained. (1) With the configuration of claim 1 in which the upper surface of the flange portion projecting left and right from the plastic lens is a horizontal flat surface, the assembly accuracy of the module assembly including the alignment of the optical system can be improved. As a result, it is possible to provide an autofocus module having a high non-defective product rate in addition to the improvement of the distance measurement performance.

(2) The plastic lens is injection-molded, and when the lens is protruded from the molding die after molding, the surface area of the lens portion is pressed to be released from the die. And the molding die according to claim 3 corresponding to this molding method, the lens is removed from the die without leaving any trace on the surface of the lens portion and without applying force to the flange portion of the lens. It can be released. Therefore, like the conventional molding die that protrudes the lens flange using the ejector pin,
It is not necessary to reinforce the flange by tapering it.

[Brief description of the drawings]

FIG. 1 is a structural view of a plastic lens according to an embodiment of the present invention, where (a) is a plan view and (b) is a side view.

FIG. 2 is a structural sectional view of a mold for molding the plastic lens of FIG. 1;

FIG. 3 is a sectional view showing the configuration of a plastic lens according to another embodiment of the present invention.

4 is a structural sectional view of a mold for molding the plastic lens of FIG.

FIG. 5 is an assembly structure diagram of the autofocus module, (a) is a plan view, (b) is a front view, and (c) is a side view.

6 (a) is a plan view and FIG. 6 (b) is a side view of the conventional plastic lens adopted in FIG.

7 is a structural sectional view of a mold for molding the plastic lens of FIG.

8 (a) and 8 (b) are views showing an assembled state using an assembling jig and a state after assembling, respectively.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plastic lens 1L, 1R Lens part 1a Flange part 2 Light-shielding box 3 Autofocus IC 4 External lead-out terminal 5 Molding die 5a Fixed type 5b Movable type 5c Lens part core also serving as ejector 5e Cavity 5f Lens part core 6 Assembly device 6a Pressing nail

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G02B 3/00 G02B 3/00 Z 7/30 B29L 11:00 // B29L 11:00 G02B 7/11 A

Claims (3)

[Claims] 1. An auto-focus module comprising an assembly of a plastic lens, a light-shielding box and an auto-focus IC, wherein the plastic lens has a flange extending laterally from both left and right ends of the lens. Positioning and bonding the optical system while fitting the lens between the lens support projections formed on the peripheral edge of the light-shielding box, placing the lens on the end surface of the light-shielding box, and pressing the flange with the holding claws of the assembly jig. Wherein the upper surface of the flange portion is formed as a horizontal flat surface. 2. The autofocus module according to claim 1, wherein the plastic lens is injection-molded, and when the lens is protruded from a molding die after molding,
A method of molding a lens of an autofocus module, wherein a surface area of a lens portion is pressed to release from a mold. 3. A lens molding method according to claim 2, wherein the lens molding die comprises a fixed die, a movable die, and a lens core which also serves as an ejector combined with the movable die, and the movable mold has a cavity surface having a lens surface. Wherein the portion corresponding to the upper surface of the flange portion is horizontal, and when the injection-molded lens is protruded from the mold, the lens molded product is released from the mold by the pushing operation of the core. Mold for molding the lens of the focus module.