JPH07199020A - Optical imaging lens system - Google Patents

Abstract

PURPOSE: To provide an optical imaging lens system which reduces degradation of the picture quality due to reflected light from the edge part of a lens and the inside wall surface of a lens barrel and can be easily set in the barrel which is made of synthetic resin for the purpose of miniaturization and reduction of the weight. CONSTITUTION: Light which is refracted in the edge parts of lenses and has large aberrations, light which is reflected by the inside wall surface of the lens barrel, etc., out of light transmitted through lenses in the lens barrel of a cam-coder 10, a camera, or the like are shielded by one or more light shielding members 30 set between lenses. This light shielding member 30 has a through groove 31 formed in the center part, namely, the part, where the optical axis passes, and is formed to have the light transmittance reduced successively toward the periphery, and therefore, most of light of small aberrations passing the center parts of lenses is transmitted, and light passing the edge parts of lenses and reflected light from the inside wall of the lens barrel are effectively more removed in more peripheral part of the light shielding member 30. This light shielding member 30 is easily set on the inside wall surface of the lens barrel made of synthetic resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical imaging lens system, and more particularly to an optical imaging lens system with corrected aberrations.

[0002]

2. Description of the Related Art An optical device such as a camcorder or a camera is a light source from an object, that is, an image pickup device (CC).
An optical imaging lens system composed of a large number of lenses is provided therein for focusing on D).
Such an optical imaging lens system does not affect the image quality because the aberration is low in the direction of the optical axis of the lens when the light source from the subject passes through many lenses, but the aberration in the outer direction of the lens is very small. Since it is very high, coma or ghost is generated to directly affect the image quality. Therefore, various techniques have been developed to correct such aberrations.

Among such techniques, in US Pat. No. 4,828,374, the aberration of light can be corrected by further installing a lens having a predetermined refractive index in the order of non-positive lens and positive lens. In addition to the above techniques, there is also known a technique for adjusting the light amount and additional aberrations with the stop when the stop reaches the stop position. Also disclosed is a technique in which a large number of thin connection grooves for reflection are provided on the inner wall surface of the lens barrel to suppress reflected light from participating in image formation through the connection grooves.

Such a conventional optical imaging lens system will be specifically described below with reference to FIG. A conventional optical imaging lens system includes a lens barrel and a plurality of lenses (L, L ...) Inside the lens barrel 1 in which a large number of lenses are aligned at predetermined intervals by spacers 2. The light source from the subject is focused through such a lens (L, L ...) And imaged on an image sensor (not shown).

[0005]

In this case, the aberration is low in the direction of the optical axis of the lens (L) and does not particularly affect the image quality, but the aberration is very large in the outer direction of the lens (L). Because it is high, it directly affects the image quality,
In particular, a part of the light source passing through the lenses (L, L ...) Is reflected by the inner wall surface of the lens barrel 1, the edge portion of the lens, a diaphragm (not shown), and the like, and then coupled to the image sensor. As a result of being imaged, it was a cause of deterioration in image quality.
That is, for example, a flare image or a ghost image is formed on the image pickup device, resulting in deterioration of image quality. Even when a lens having a predetermined refractive index is additionally installed for aberration correction as in the above-mentioned US Pat. No. 4,828,374, it is reflected by the inner wall surface of the lens barrel or the edge portion of the lens. There is a problem in that it is difficult to reduce the size of the optical device because it is not possible to prevent the deterioration of the image quality due to the reflected light, but rather to increase the number of lenses. In addition, among the above-mentioned conventional techniques, the technique of suppressing the transmission of reflected light by a large number of thin connecting grooves is possible only when the material of the lens barrel is a metal material (for example, an aluminum alloy), and is recently small and lightweight. However, in the case of a lens barrel made of a synthetic resin, it is not applicable to mold injection.

[0006]

SUMMARY OF THE INVENTION Therefore, in order to solve the above problems, an object of the present invention is to provide an optical system capable of minimizing the deterioration of the image quality due to the reflected light reflected on the edge portion of the lens and the inner wall surface of the lens barrel. It provides an imaging lens system. Still another object of the present invention is to provide an optical imaging lens system which can be easily installed in a lens barrel formed of synthetic resin for weight reduction.

In order to achieve the above-mentioned object of the present invention,
The present invention relates to a lens barrel; a plurality of lenses that are aligned while maintaining a predetermined interval by spacers formed on the inner surface of the lens barrel to form an image of a subject on an image sensor; An optical imaging lens system is provided that includes at least one light blocking member having a sequential transmittance between the plurality of lenses to block reflected light reflected from the inner wall surface.

According to one embodiment of the present invention, the light blocking member is installed between the lenses in a form that is aligned with the inner wall of the lens barrel in a direction perpendicular to the optical axis direction in the lens barrel. A through groove having a predetermined size is formed in the member around the optical axis direction of the lens barrel, and the light blocking member is a light blocking member whose transmittance gradually decreases toward the outer periphery around the through groove. It is formed.

According to one embodiment of the present invention, the light blocking member is supported on the inner peripheral surface of the spacer. Therefore, according to the present invention, it is possible to maximally prevent the light source from being reflected from a subject at a portion having a large aberration such as a lens edge portion, or being reflected at a lens barrel portion and being imaged on an image sensor. The image quality can be improved. Further, there is an advantage that the light shielding member can be easily installed on the inner wall surface of the lens barrel made of synthetic resin.

[0010]

The optical imaging lens system according to the present invention will be described in detail below with reference to the accompanying drawings.
2 is a schematic cross-sectional view of the optical imaging lens system according to the present invention, and FIG. 3 is a side view taken along the line AA of FIG.

Reference numeral 10 is a lens barrel of a camcorder (or camera). Inside the lens barrel 10, a plurality of lenses (L, L ...) Having a predetermined refractive index are arranged while maintaining an appropriate interval. In order to maintain the above-mentioned lenses at a constant distance from each other, spacers 20 are formed so as to project along the inner peripheral surface of the inner wall surface of the lens barrel between the lenses. In addition, one or more light-shielding members 30 are installed on the inner wall of the lens barrel in a direction perpendicular to the optical axis direction between the lenses in the lens barrel. For example, the outer peripheral surface of the member 30 is the inner circumference of the inner wall of the lens barrel. It is installed in such a manner that it is fitted and fixed in a groove having a predetermined depth formed along the surface. A through groove 31 of a predetermined size is formed in the center of the light blocking member 30 with the optical axis direction of the lens barrel as the center, and the light penetrates toward the outer portion of the light blocking member 30 with the through groove 31 as the center. The rates are arranged to be progressively lower. When a light source from a subject passes through the lens barrel and a plurality of lenses, it is reflected by the inner wall of the lens barrel or refracted or reflected at the edge of the lens, resulting in flare, ghost, etc. At least one or more suitable positions are provided between the lenses in order to appropriately remove light. Further, when the distance between the lenses (L, L ...) Is narrow, a groove 21 having a predetermined depth is formed on the inner peripheral surface of the spacer 20 provided to maintain the distance between the lenses L. It is preferable that the light-shielding member 30 is formed and the outer peripheral surface of the light-shielding member 30 is fitted and fixed in the groove.

The operation of the optical imaging lens system according to the present invention will be described below. The light scanned from the object is the plurality of lenses L inside the lens barrel.
An image is formed by passing through the image pickup device (not shown) and being focused. However, in this case
Since light having a relatively small aberration that passes through the vicinity of the center of the optical axis of the lens L passes through the through groove 31 of the light blocking member, it is completely blocked without being blocked by the light blocking member 30. On the other hand, the light having a relatively large aberration that is incident from a non-axis at a large angle and is refracted and transmitted at the edge portion of the lens (L, L ...) Or the reflected light reflected on the inner wall surface of the lens barrel 10 is The peripheral portion of the light blocking member 30 provided during (L, L ...) Is mainly scanned.
As described above, the light incident on the peripheral portion is partially shielded by the light shielding member 30. Here, since the reflected light and the aberration phenomenon described above become deeper toward the edge portion of the lens and the inner wall surface of the lens barrel, the transmittance of the light blocking member 30 increases toward the outer direction, that is, the inner wall surface of the lens barrel. The lower the lens, the more the image of a flare or the ghost can be suppressed.

[0013]

As described above, according to the optical imaging lens system of the present invention, in a light source that transmits a lens in a lens barrel in a camcorder, a camera or the like, light having a large aberration is refracted at an edge portion of the lens. Also, by blocking light or the like reflected on the inner wall of the lens barrel by one or more light blocking members installed between the lenses, a virtual image such as a shadow or the like generated as a result of being reflected on the inner wall and a faint image. The image is suppressed from being formed to the maximum, so that a clearer image can be formed on the image pickup device. The light-shielding member has a through groove formed in the central portion thereof, that is, a portion through which the optical axis passes, and is formed so as to have a lower light transmittance toward the peripheral portion thereof. Most of the low-aberration light that passes through the lens will be transmitted, and the light that passes through the edge of the lens and the light reflected by the inner wall of the lens barrel can be removed more effectively toward the periphery. , A clearer image can be obtained. Further, since the light shielding member of the present invention can be easily installed on the inner wall surface of the lens barrel made of synthetic resin, it is possible to reduce the size and weight of the product.

Although the present invention has been specifically described with reference to the above embodiments, the present invention is not limited to this, and modifications and improvements can be made within the scope of ordinary knowledge of those skilled in the art.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a conventional optical imaging lens system.

FIG. 2 is a schematic cross-sectional view of an optical imaging lens system according to the present invention.

3 is a side sectional view taken along the line AA of FIG.

[Explanation of symbols]

 10 Camcorder 21 Groove 20 Spacer 30 Light-shielding member 31 Through-groove

Claims (6)

[Claims] 1. A lens barrel; a plurality of lenses aligned for maintaining an image of a subject on an image pickup device by spacers formed on the inner surface of the lens barrel while maintaining a predetermined interval; An optical imaging lens system comprising at least one light blocking means having a predetermined transmittance between the plurality of lenses to block the reflected light reflected from the inner wall surface of the lens. 2. The optical imaging lens system according to claim 1, wherein the light-shielding means is formed of a light-shielding member whose transmittance gradually decreases toward its periphery. 3. The optical imaging lens system according to claim 1, wherein the light shielding means is formed with a through groove having a predetermined size centered on the optical axis direction of the lens barrel. 4. The optical imaging lens system according to claim 3, wherein the light-shielding means is formed of a light-shielding member whose transmittance gradually decreases toward its peripheral portion. 5. The light-shielding means is installed between the lenses in a manner that it is supported on the inner peripheral surface of the inner wall of the lens barrel in a direction perpendicular to the optical axis direction in the lens barrel. Item 1
The described optical imaging lens system. 6. The light shielding means is installed in a form supported by the inner peripheral surface of the spacer.
The described optical imaging system.