JPH0540305A - Projecting lens device - Google Patents

Abstract

PURPOSE:To eliminate the nonuniform deformation of an OC lens which is induced by the shrinkage on maturation of an adhesive at the time of liquidtightly adhering the OC lens by the adhesive to an OC housing and to obviate the generation of a degradation in imaging performance with an optical coupling system for optically bonding the space between a cathode ray tube and the projecting lens with liquid having high transparency. CONSTITUTION:The spacer 23 consisting of a rubber material, etc., having the elasticity equiv. to the elasticity when the adhesive is matured by polymn. is interposed between the OC housing 21 and the lens 25 to be adhered, by which the housing and the lens are positioned and adhered. Even if the adhesive is shrunk by the polymn., the spacer 23 absorbs this shrinkage when the housing and the lens are adhered in such a manner. The generation of strains is thus eliminated without allowing nonuniform stresses to act on the lens. The initial imaging performance is thus maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection lens used for enlarging and projecting an image projected on a relatively small cathode ray tube or the like on a screen, and a projection television equipped with the projection lens.

[0002]

2. Description of the Related Art In order to obtain a television image on a large screen, a method of projecting a television image on a relatively small cathode ray tube (cathode ray tube) and enlarging and projecting it on a screen by a projection lens is a well-known technique. Recently, in many projection televisions, the space between the projection lens and the cathode ray tube is filled with a highly transparent liquid or gel-like substance,
By optically coupling, the emission light from the cathode ray tube is introduced into the projection lens efficiently by reducing the interface reflection.
A method of improving the sharpness and contrast of the projected image is adopted. Generally this is an optical coupling (O
C) method.

FIG. 2 shows one of the conventional examples. In the figure, reference numeral 1 is a projection lens, 2 is an OC housing, a cathode ray tube 3 for displaying an image is attached on the right side, and an OC located at the right end of a lens element group forming the projection lens 1 is on the left side. The lens 4 is liquid-tightly attached by adhesion. A seal rubber groove 5 is formed in the OC housing 2,
A seal rubber 6 is inserted in the groove. When the cathode ray tube 3 is placed on the OC housing 2 by pressing from the right side,
Since the seal rubber 6 is pressed and deformed and comes into close contact with the pressing surface, a sealing capable of liquid sealing is performed. OC housing 2,
An optical coupling liquid 7 (hereinafter referred to as OC liquid) is enclosed in a closed space surrounded by the cathode ray tube 3 and the OC lens 4.
After injecting a predetermined amount from the injection hole 8, the injection hole 8 is sealed so that the OC liquid 7 does not leak. At present, as the OC liquid, ethylene glycol, a mixture of ethylene glycol and glycerin, a mixture of ethylene glycol and water, and the like are generally often used.

When the OC lens 4 is bonded to the OC housing 2, highly accurate positioning is required. As the positioning in the optical axis direction, as shown in FIG. 3, the contact protrusions 10 are provided at several places around the adhesive white portion 9 of the OC housing 2.
Are formed. Further, as the radial positioning, an annular guide portion 11 is formed that fits smoothly with the outer peripheral edge of the OC lens 4 without rattling. The OC lens 4 is adhered to the adhesive housing 9 of the OC housing 2 by applying an appropriate amount of adhesive, and then fitting the OC lens 4 into the annular guide portion 11 while the outer peripheral adhesive portion of the OC lens 4 is in contact. Push in until it hits the protrusion 10. Then, while maintaining this state, it is carried into a constant temperature bath at about 80 ° C. and the adhesive is aged to complete the bonding of the OC lens 4.

[0005]

Generally, an adhesive contracts when it is polymerized and aged, and internal stress is generated such that the adherends facing each other with the adhesive layer sandwiched therebetween are attracted to each other. With the OC lens 4 bonding method as shown in the conventional example, the distance between the contact protrusion 10 and the contact protrusion 10 is maintained in the vicinity of the contact protrusion 10 because the lens and the contact protrusion 10 are in contact with each other even when the adhesive layer contracts. It However, the other parts are attracted by the contracting action of the adhesive, so that non-uniform deformation occurs. The effect also deforms the shape of the optically effective surface of the lens. The degree of this deformation is difficult to visually recognize, but has a great influence on the imaging performance of the projection lens.

The present invention provides a projection lens device which eliminates the non-uniform deformation of the OC lens 4 caused by such aging shrinkage of the adhesive and does not cause the deterioration of the imaging performance.

[0007]

When the OC lens, which is the object to be adhered, is placed on the OC housing, the positioning in the optical axis direction is made by abutting against the contact projection 10 in the conventional example. However, this causes the OC lens to deform after the polymerization shrinkage of the adhesive rubber. Therefore, in the present invention, the contact projection 11 is eliminated and replaced with an OC
As positioning in the optical axis direction when the lens is placed, a plurality of small blocks made of rubber are arranged or an O ring is arranged so that the OC lens is positioned and the thickness of the adhesive layer is secured at the same time. There is. It is desirable that the kind of the rubber of the small block or the O-ring is the same as that of the adhesive rubber, or that the rubber hardness is about the same as the hardness when the adhesive rubber is polymerized and aged.

[0008]

According to the present invention, when the OC lens is mounted on the OC housing, the positioning of the OC lens in the optical axis direction is performed by a small block of rubber material or an O-ring. The small block or the O-ring is deformed following without being stretched. Therefore, a non-uniform force does not act on the peripheral edge portion of the lens, distortion does not occur on the lens optical effective surface, and the imaging performance does not deteriorate.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view showing the overall structure of an embodiment of the present invention.

In the figure, the OC housing 21 has a circular groove-shaped O
A ring groove 22 is formed, and an O-ring 23 as a spacer having a substantially rectangular cross section is inserted therein. Now, on the left side of the OC housing 21, there is a projection lens 24.
Of the lens element group forming the
The lens 25 is present, and the edge flat portion 26 of the OC lens 25 is present.
However, when it comes into contact with the O-ring 23, it becomes a predetermined axial mounting position. At this time, the radial alignment is OC
An annular guide portion 27 is formed on the housing 21,
It is finished so as to fit smoothly with the outer peripheral edge of the C lens 25.

In order to secure the thickness of the adhesive layer, an adhesive space 30 of about 1 mm is provided between the edge flat portion 26 and the adhesive silo surface 28 of the OC housing 21 in a state where the edge flat portion 26 is in contact with the O-ring 23. It is formed. To attach the OC lens 25, a proper amount of rubber adhesive is annularly applied to this portion in advance, and then the OC lens 25 is placed, and if the edge flat portion 26 is pushed into contact with the O-ring 23, the rubber is attached. The adhesive is spread and spread evenly in the bonding space 30. If the rubber adhesive is polymerized and aged while maintaining this state, the bonding of the OC lens 25 is completed. The O-ring 23 has a ring shape having an outer diameter slightly smaller than the maximum diameter of the OC lens 25. The shape is not limited to the quadrangular shape, but may be a circular shape or another polygonal shape.

A cathode ray tube 29 is attached to the right side of the OC housing 21 as in the conventional example.

[0013]

As described above, according to the present invention, O
Even if the adhesive that adheres the C lens is polymerized and contracted, the spacer that also functions as positioning when the lens is placed uses a rubber material, so it is not necessary to stretch against the contraction of the adhesive. In other words, the induction of uneven stress in the outer peripheral portion of the lens is eliminated. As a result, the shape of the optically effective surface of the lens is kept the same as that before the attachment, and the image forming performance is not deteriorated.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a projection lens device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a projection lens device for explaining a conventional OC lens bonding method.

FIG. 3 is a front view of an OC housing in a conventional example.

[Explanation of symbols]

 21 OC Housing 22 O Ring Groove 23 O Ring 24 Projection Lens 25 OC Lens 26 Edge Flat Part 27 Annular Guide Part 28 Adhesive White Surface 29 CRT 30 Adhesive Space

Claims (3)

[Claims] 1. A display device such as a cathode ray tube or a liquid crystal panel for displaying an image, and a projection lens including a plurality of lens elements for enlarging the image,
When the lens element closest to the display device among the plurality of lens elements is bonded to the OC housing by using an adhesive such as a silicone rubber adhesive that causes rubber elasticity after aging, the OC housing and the lens element are separated from each other. A projection lens device characterized in that an elastic material spacer having rubber elasticity is interposed to form an adhesive layer between the two. 2. The projection lens device according to claim 1, wherein the elastic material spacer has a ring shape having an outer diameter slightly smaller than the maximum diameter of the lens element. 3. The projection lens apparatus according to claim 2, wherein the ring-shaped elastic material spacer has a circular, quadrangular or polygonal cross-sectional shape.