JPH1152108A - Resin-molded lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin molded lens for photography in which flares are suppressed from occurring without lowering the accuracy of the surface of the lens and whose assembling to a lens holding member is easy. SOLUTION: A lens 20 is constituted by providing a core lens part 22 at the outer periphery of the effective lens part 21 in which a lens surface 21b is formed. The length in the radial direction of the core lens part 22 is formed long so that the light quantity of the reflected light at a lens peripheral surface 23 beomes the degree to which it does not lower the contrast of a subject. Moreover, one pair of engaging parts 26, 27 are provided in the up and down parts of an effective light beam passing range 25 in the core lens part 22. Thicknesses of the parts 26, 27 ate constituted to be thinner than the thickness at the outermost peripheral part of an effective lens part 21 and the volume of the outer peripheral part of the lens 20 is suppressed from being increased. Since the engaging part 16, 17 are engaged in one of groove part provided in a lens holding member by bending the whole of the lens 20, the lens 20 is held in the holding member and, is fixed to it simultaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shape of a resin molded lens for photography.

[0002]

2. Description of the Related Art At present, a great number of types of cameras for photographing are manufactured and sold according to applications and functions. In recent years, a lens-equipped film unit in which an unexposed photographic film is built in advance in a unit body incorporating a photographic mechanism such as a photographic lens and a shutter device has been sold so that photographers can easily enjoy photography at any time. . Such a film unit with a lens is generally widely used because it is easy to take a photograph immediately upon purchase, and it is easy to take the photographer directly to a developing dealer after the photographing.

[0003] In such a film unit with a lens or a camera in a low-priced range, a resin lens molded by an injection molding method is generally used as a photographing lens. The resin lens is positioned by being held by a lens holding member. Conventionally, when a lens is held by a lens holding member, the holding member is held by the lens holding member together with the lens, or a part of the lens holding member is swaged to the periphery of the lens, or the lens and the lens holding member are The gap between the lens and the lens holding member is eliminated by a method such as bonding. Thereby, the lens is prevented from rattling in the lens holding member, and the optical performance of the lens is maintained in a good state.

It is known that a phenomenon called flare occurs when a photograph is taken in a place having a bright light source such as the sun or a room light. This phenomenon occurs because strong light such as sunlight is reflected on the peripheral surface of the taking lens or the inner wall of the lens holding member and gives stray light to a part or the whole of the taking picture, which lowers the contrast of the subject image. Let it.

FIG. 6 shows a general configuration of a resin molded lens used as a photographing lens. Lens 5
Has a structure in which a core lens portion 7 is integrally provided on an outer periphery of an effective lens portion 6 on which lens surfaces 6a and 6b are formed. The core lens portion 7 is held by a lens holding frame 9 and positioned. In such a lens 5, for example, as shown in FIG. 7, the length L in the radiation direction of the core lens portion 7 is configured to be long, and the distance between the lens surfaces 6 a and 6 b and the lens peripheral surface 8 is increased, thereby Flare phenomenon can be reduced. That is, as the length L increases, the area of the lens peripheral surface 8 that enters the optical path of the incident light decreases, so that the amount of light reflected by the lens peripheral surface 8 and traveling toward the photographing screen also decreases. The occurrence of flare can be suppressed.

[0006]

However, when this method is used for a negative lens having a concave lens surface, the volume of the peripheral portion of the lens increases, and the light is emitted between the central portion and the peripheral portion of the lens. A large difference occurs in the shrinkage ratio of the resin after molding. For this reason, the lens surface easily bends after injection molding, and it becomes difficult to maintain a high surface accuracy of the lens.

As described above, in order to fix the lens in the lens holding member, after the lens is held by the lens holding member, a process such as mounting, crimping, and bonding of the pressing member must be performed. No. For this reason, in the conventional lens, not only many man-hours are required for assembling to the lens holding member, but also high assembling accuracy is required.

The present invention has been made in view of the above circumstances, and provides a resin molded lens that suppresses the occurrence of flare and that can be easily assembled to a lens holding member without lowering the surface accuracy of the lens. The purpose is to:

[0009]

In order to achieve the above object, a resin molded lens according to the present invention comprises a core lens portion for providing a certain amount of margin on the outer periphery of an effective lens portion having a lens surface formed thereon. And chamfering a corner formed by the object-side surface of the core lens portion and the lens peripheral surface within a range that does not block the optical path of the incident light.

According to a second aspect of the present invention, there is provided a resin molded lens, wherein a core lens portion is provided on the outer periphery of the effective lens portion on which the lens surface is formed so as to have a certain amount of margin, and the core lens portion is provided. A pair of locking portions is provided in which the peripheral portion of the lens is configured to be thinner than the thickness at the outermost peripheral portion of the effective lens portion, the entire lens is bent, and a pair of locking portions is provided on the lens holding member. It is fixed to the lens holding member by fitting it into the groove. It is preferable that the pair of locking portions be provided at an upper portion and a lower portion of an effective light beam passing range through which a light beam directed to the horizontally long exposure screen passes.

[0011]

FIG. 1 shows a first embodiment of a resin molded lens according to the present invention. The lens 10 is a negative lens having a concave lens surface, and is injection-molded with resin. The lens 10 has a core lens portion 12 on the outer periphery of the effective lens portion 11 having lens surfaces 11a and 11b formed thereon.
Are provided integrally. The core lens portion 12 is provided with a support portion 13 protruding stepwise out of the optical path of the incident light at a position close to the effective lens portion 11. The lens 10 is positioned on the back side of the lens opening 14a by bringing the support portion 13 into contact with the inner wall of the lens holding frame 14.

Light incident at an acute angle with respect to the object-side lens surface 11a is reflected by the lens peripheral surface 15 into an exposure screen (not shown), causing a flare phenomenon. However, as the length L in the radiation direction of the core lens portion 12 increases, the area of the lens peripheral surface 15 that enters the optical path of the incident light decreases, so that the amount of reflected light in the exposure screen decreases. Therefore,
The length L in the radial direction of the core lens unit 12 is equal to the lens peripheral surface 1.
The light quantity of the reflected light at 5 is determined so as not to lower the contrast of the subject image formed on the exposure screen, and is configured to be longer than usual.

As shown in FIG. 2, the core lens unit 12
Corner 16 composed of object-side surface 12a and lens peripheral surface 15
Is chamfered. This corner 16 is formed on the lens surface 11a.
The chamfered surface 16a formed by the chamfering does not intersect with the optical path of the incident light so as not to block the optical path of the light incident from the light source.

In the lens 10 configured as described above, since the core lens portion 12 is provided integrally with the outer periphery of the effective lens portion 11, the volume of the peripheral portion is increased. However, since the corner 16 formed by the object side surface 12a of the core lens portion 12 and the lens peripheral surface 15 is chamfered to reduce the volume, the volume ratio between the central portion and the peripheral portion of the lens 10 increases. Is suppressed, and the difference in shrinkage of the resin is reduced. Also, since the chamfered surface 16a formed by chamfering the corner 16 does not intersect with the optical path of the incident light from the lens surface 11a,
The incident light is not reflected on the chamfered surface 16a and enters the exposure screen. Therefore, while the lens 10 is configured to have a large outer diameter in order to suppress the occurrence of flare, bending of the lens due to contraction of the resin after injection molding is suppressed, and the surface accuracy of the lens surface can be maintained at a high level. .

Next, a second embodiment of the resin molded lens of the present invention will be described with reference to FIGS. As shown in FIGS. 3 and 4, the lens 20 is a negative lens having a concave lens surface, and is formed by injection molding with a resin. This lens 20 has lens surfaces 21a, 21b
The configuration is such that a core lens portion 22 is provided on the outer periphery of the effective lens portion 21 on which (see FIG. 5) is formed. The length L in the radiation direction is configured to be long so that the amount of reflected light on the lens peripheral surface 23 does not decrease the contrast of the subject image formed on the exposure screen. I have.

The core lens portion 22 is parallel to the upper and lower sides of an effective light beam passing range 25 through which light beams traveling toward the exposure screen 24 defined in the horizontal direction pass, and the effective lens portion 2.
A pair of upper and lower locking portions 26 and 27 having the bases at the boundary portions 26a and 27a in contact with the contour portion 1 are provided.

As shown in FIG. 5, the lens 20 is held by a lens holding frame 30. The lens holding frame 30 is formed with a lens opening 31 for restricting light incident on the lens 20, and a pair of upper and lower portions of the lens opening 31 projecting toward the inner wall 30 a of the lens holding frame 30. Locking claws 32 and 33 are provided. The lens 20 is positioned and fixed on the back surface of the lens opening 31 by bending the entire lens and fitting the locking portions 26 and 27 into the gaps between the locking claws 32 and 33 and the inner wall 30 b of the lens holding frame 30. Is done. The locking portions 26 and 27 have respective thicknesses Dc.
Is formed to be thinner than the thickness De at the outermost peripheral portion of the effective lens portion 21.

The lens 20 is held in the lens holding frame 30 at the same time as the lens 20 is fixed in the lens holding frame 30. There is no need to perform processing such as mounting of a pressing member, crimping, and bonding unlike a conventional lens. Therefore, the assembling work is simplified. Further, since the locking portions 26 and 27 are defined above and below the effective light beam passing range 25 where the distance from the periphery of the lens 20 to the effective light beam passing range 25 is longest, the force for pressing the locking portions 26 and 27 is small. It does not extend into the effective light beam passing range 25. Therefore, the lens 20 is
The surface condition of 1a, 21b is at least the effective light ray passing range 2
5 is well maintained.

Since the thickness Dc of the locking portions 26 and 27 is configured to be smaller than the thickness De at the outermost peripheral portion of the effective lens portion 21, the lens 20 has a volume between the central portion and the peripheral portion. The ratio becomes small, and bending due to shrinkage of the resin after injection molding is prevented. Thereby, the surface state of the lens surfaces 21a and 21b is favorably maintained.

In the second embodiment, the locking claw is provided on the lens holding frame, and the locking portion of the lens is fitted between the locking claw and the inner wall of the lens holding frame. A pair of grooves may be formed on the inner wall of the lens holding frame at a distance substantially equal to the outer diameter of the lens and opposed to each other, and the edge of the locking portion may be fitted into this groove. According to this embodiment, since the shape of the lens holding frame is simplified as compared with the case where the locking claws are protruded, the molding can be easily performed.

In the lens of the second embodiment, similarly to the lens of the first embodiment, if the corner formed by the object-side surface of the core lens portion and the lens peripheral surface is chamfered, the peripheral portion of the lens can be obtained. Is further reduced, and bending of the lens after injection molding can be reliably prevented.

[0022]

As described above, according to the resin molded lens of the present invention, a core lens portion for providing a certain amount of margin on the outer periphery of the effective lens portion having the lens surface is provided.
Since the distance between the lens surface and the lens peripheral surface is configured to be long, the amount of light entering the lens peripheral surface into the optical path is reduced. This reduces the amount of reflected light into the exposure screen and suppresses flare. Furthermore, since the volume of the peripheral portion of the lens is reduced by chamfering the corner portion of the core lens portion, an increase in the volume ratio between the central portion and the peripheral portion of the lens is suppressed, and the difference in shrinkage of the resin is reduced. Therefore, in the resin molded lens of the present invention, the bending of the lens due to the contraction of the resin after the injection molding is suppressed, and the surface accuracy of the lens surface can be maintained at a high level. Further, since the corner of the core lens portion is chamfered in a range that does not block the optical path of the incident light, the incident light is prevented from being reflected by the chamfered surface and entering the exposure screen.

In the resin molded lens of the present invention, the entire lens is bent, and the engaging portions provided on the peripheral portion are fitted into the grooves provided in the lens holding member, so that the lens is inserted into the lens holding member. Since the lens is fixed, the lens is held at the same time as being held by the lens holding member. Therefore, since no processing step is required other than the lens holding step, the lens can be easily assembled.

Further, by providing the pair of locking portions above and below the effective light beam passing range where the distance from the periphery of the lens to the effective light beam passing range is longest, the pressing force applied to the locking portions can be reduced. To the inside. Thereby, the surface state of the lens surface is favorably maintained at least within the effective light beam passage range.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a resin molded lens of the present invention.

FIG. 2 is a schematic view showing a main part of the resin molded lens shown in FIG.

FIG. 3 is a perspective view showing another configuration of the resin molded lens of the present invention.

FIG. 4 is a front view of the resin molded lens shown in FIG.

FIG. 5 is a cross-sectional view showing a state where the resin molded lens shown in FIG. 3 is held by a lens holding frame.

FIG. 6 is a sectional view showing a configuration of a conventional resin molded lens.

FIG. 7 is an explanatory diagram showing a relationship between the size of the core lens unit shown in FIG. 6 and a reflection area of the lens peripheral surface with respect to incident light.

[Explanation of symbols]

5, 10, 20 lens 6, 11, 21 effective lens portion 6a, 6b, 11a, 11b, 21a, 21b lens surface 7, 12, 22 core lens portion 8, 15, 23 lens peripheral surface 9, 14, 30 lens holding Frame 16 Corner 16a Chamfered surface 25 Effective light passage range 26,27 Locking portion 32,33 Locking claw

Claims (3)

[Claims] 1. A core lens for providing a certain amount of margin on an outer periphery of an effective lens portion having a lens surface formed by injection molding with a resin, and an object side of the core lens portion. A resin molded lens characterized in that a corner formed by the surface of (1) and the lens peripheral surface is chamfered in a range not to block the optical path of incident light. 2. A photographic lens which is injection-molded with a resin and is used while being held by a lens holding member, wherein the effective lens portion on which the lens surface is formed has a certain margin on the outer periphery thereof. The core lens portion is provided, and a pair of locking portions configured so that a peripheral portion of the core lens portion is thinner than a thickness of an outermost peripheral portion of the effective lens portion is provided, and the entire lens is bent. A resin molded lens, wherein the pair of locking portions are fixed to the lens holding member by being fitted into a pair of grooves provided in the lens holding member. 3. The apparatus according to claim 2, wherein the pair of locking portions are provided at an upper portion and a lower portion of an effective light beam passing range through which a light beam directed to the horizontally long exposure screen passes.
The resin-molded lens according to the above.