JPS59124301A - Prism - Google Patents

Abstract

PURPOSE:To obtain a prism of which the sepn. angle hardly changes with a temp. change by pasting two sheets of transparent materials of which the ratio of the respective refractive indices is approximately equal to the ratio of the respective temp. coeffts., and using the boundary face thereof as a prism face. CONSTITUTION:A prism plate 18 is formed by pasting two transparent materials 18a and 18b having a prescribed angle alpha of inclination and the boundary face thereof is constituted as a prism face. A sepn. angle theta is determined by n2/n1 from the equation where the refractive index of the material 18a is designated as n1, the coefft. of temp. as DELTAn1, the refractive index of the material 18b as n2, the coefft. of temp. as DELTAn2, a solid line A as a prism face, an incident angle as alpha and the sepn. angle as theta. If the respective refractive indices upon changing of the temp. by DELTAt, as designated as n1(t), n2(t), are so selected as to make n2/n1 and DELTAn2/DELTAn1 approximately equal, the prism of which the sepn. angle theta hardly changes with the temp. change is obtd. as shown by the equation.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a prism suitable for application to a prism plate used, for example, in a projection television receiver.

BACKGROUND ART AND PROBLEMS A projection television receiver using a color cathode ray tube is basically constructed as shown in FIG.

In the same figure, (1) shows a color cathode ray tube in which the fluorescent surface (1a) is a striped color value light body.
Is the image light from above the projection lens (3)? The enlarged image (
5) is obtained. In this case, an enlarged image (5) is obtained on the screen (4), and at the same time, as shown in FIG.
The i9 turn (color stripe pattern) of the stripe-shaped color value light material that constitutes this fluorescent surface (1a) is also enlarged and projected on the screen (4) and becomes conspicuous. ) The enlarged image (5) above becomes difficult to see.

Conventionally, in order to make the nine turns of color striations on the screen (4) less noticeable, a predetermined angle of inclination was set between the projection lens (3) and the color cathode ray tube (1), as shown in Figure 3. It has been proposed to arrange a prism plate (6) having α. In this case, the image light from the point P on the fluorescent surface (la) of the color cathode ray tube (1) is transmitted to the prism surfaces (6a) and (6b) of one and the other prism plate (6).
), the optical path is divided into two parts and projected onto two points Pa and pb on the screen (4). Therefore, on the screen (4), as shown in FIG.
) is formed, and as a result, on the block IJ-n (4),
An enlarged image (5) is obtained by combining these enlarged images (5a) and (5b). In the end, the number of color stripes in the enlarged image (5) is doubled, so the screen (4)
), the color stripe f-turn becomes less noticeable.

However, in the example shown in FIG. changes, and the above-mentioned prism plate (6)
There was a drawback that the effect obtained by disposing the .

OBJECTS OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to propose a prism whose separation angle hardly changes even when the degree of popularity changes.

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a first
A first transparent material having a temperature coefficient of The ratio of the second refractive index and the ratio of the first temperature coefficient and the second temperature coefficient are selected to be approximately equal.

Since the present invention is configured in this manner, even if the refractive index changes due to temperature changes, the separation angle hardly changes.

EXAMPLE Hereinafter, an example in which the present invention is applied to a prism plate used in a projection type television receiver will be explained with reference to FIG. 5 and subsequent figures.

In FIG. 5, (11 p) is a color cathode ray tube whose fluorescent surface (XOa) is a striped color phosphor or turn, and (10b) is a face plate.

Further, α is a fixed frame on the side of the color cathode ray tube α1, and is made of aluminum, for example. On the outside of the fixed frame (11), an uneven heat dissipating portion (lla) and a collar portion (], xb) are formed. A convex fixing part (llc) is formed inside this fixing frame α force, and furthermore, the contact area with the liquid to be injected is made small at the tip of this fixing part (lie) as described later, A lid is formed which enhances the cooling effect. Moreover, the inside of this fixed frame 0η is processed to be black. This fixing frame a is adhesively fixed to the face gray (1ob) of the color cathode ray tube α0 using an adhesive (6) such as silicone resin. Further, a glass plate α for absorbing X-rays is adhesively fixed to the fixing portion (llc) of the fixing frame (11) using an adhesive α.

Further, α→ is a fixed frame on the projection lens side, and is made of aluminum, for example. The outside of this fixed frame α is provided with a flange (
14a) is formed, and a convex fixing part (14a) is formed inside it.
b) is formed. The inside of this fixed frame α→ is processed to be black.

This fixed frame Q4 is fixed to the above-mentioned fixed frame 0 through a gasket made of an elastic material such as rubber. llb) and (14a) are used, and Patsukin α is used in between.
→ is interposed between the bolt (16a) and the nut (1
6b). Note that the opening η is, for example, a spacer made of aluminum.

Furthermore, a prism plate α on which a plurality of prisms having a predetermined inclination angle α are formed is fixed with an adhesive (6) to the color cathode ray tube α side of the fixing portion (14b) of the fixing frame ←→. Further, a lens barrel to which a concave lens (19a) constituting the projection lens α is fixed with an adhesive (6) is fixed to the fixed frame α→. This lens barrel (A) is
For example, it is made of plastic, and the inside is painted black. A lens barrel Cυ to which convex lenses (19b) and (19c) constituting the projection lens (6) are fixed is fitted inside the lens barrel. This lens barrel (21) is also made of plastic, for example, and its interior is painted black.

In addition, in this example, a color cathode ray tube αQ and a glass plate (
6), between the glass plate α→ and the prism plate (c), and between the prism plate α and the concave lens (19a), a transparent liquid (for example, ethylene glycol) is injected.

In this case, for example, a through hole is formed in the aluminum spacer at a predetermined position η, and the through hole is passed through the spacer.
For example, a syringe needle is inserted through the skin α0, and a transparent liquid (22) is injected with this needle. In this case, for example, through holes are formed at the prism plate α and at the end of the glass plate (B), so that the transparent liquid (2) is uniformly injected into each space.

Further, the prism plate (A) has a structure in which two transparent materials (, 1B&) and (18b) are aligned and the interface thereof is a prism surface, as shown in FIG. 6B. Then, the refractive index of the transparent material (18a) is nl%, and the temperature coefficient is Δ
When n1 is the refractive index of the transparent material (18b) and n2 is the temperature coefficient, Δn2 is the refractive index of the transparent material (18b). l! The transparent materials (1sa) and (18b) are selected so that -akiJn2. For example, as a transparent material (18a), refractive index n1 (25°C) = 1.5
43, temperature coefficient Δnl = 1.35 x 10-'
An epoxy resin with a temperature of / °C and a refractive index n2 (25 °C) -1,508 is chosen as the transparent material (18b).

An epoxy resin crab with a temperature coefficient Δnz = -1,30X 10-'/°C is chosen. This is because, as shown in FIG. 6A, in a case made of a single transparent material (18e), the separation angle changes due to changes in the refractive index due to temperature changes, and the separation angle changes on the screen. This is to avoid the disadvantage that the shift amount of the enlarged image changes, making it impossible to obtain the above-mentioned effect by arranging the prism plate. That is, as shown in Fig. 7, when the solid line A is the prism surface, the incident angle is α, and the separation angle is θ, then n2 ratio α=n1sin (α-θ)...
・・・・・・・・・・・・The relationship in (1) is satisfied, and the separation angle θ is θ−α−5in−1('ρS stone α)・・・・・・・・・
It can be expressed as (2)1, and the separation angle θ is determined by the town. Here, when the temperature changes by Δt, each refractive index is nl(
1) and n2(1), it can be expressed as Δn2 mu n2. Here, if it is selected so that 亙−π, then = constant・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・(4) Therefore,
When the prism plate α is configured as in this example, there is almost no change in the separation angle θ due to temperature changes.

Further, this prism plate q is manufactured, for example, by a process as shown in FIG. First, as shown in the figure, a mold (23) for obtaining a predetermined prism surface is prepared.

Next, as shown in FIG. harden,
It is molded as shown in FIG. Next, as shown in the same figure, this molded transparent material (18a) and the glass plate C!
A spacer C25) is used to form an empty space between ◇, and the transparent material (18b) is injected into this space and cured. Then, by releasing the mold, transparent materials (1B &) and (18b) are formed, as shown in Figure E.
A prism plate 0→ is obtained by gluing them together.

In this way, according to this example, the prism board → is the same as the above-mentioned A
It has a structure in which two transparent materials (XSa) and (18b) are bonded together, and there is almost no change in the separation angle θ due to temperature changes, so the effect of arranging the prism plate can be fully demonstrated.

In addition, between the color cathode ray tube (10 and the glass plate (6),
Since a transparent liquid (22) is injected into the glass plate between the hole and the prism plate (1) and between the prism plate 0 frame and the concave lens (19a), the refraction is lower than when there is air between each. It is possible to reduce the reflection at the interface due to the difference in ratio.Therefore, it is possible to prevent the occurrence of multiple reflection images and a large loss of light quantity.Also, since the transparent liquid (22) is injected, this liquid cooling As a further advantage, the thermal expansion of each part can be suppressed to a low level, and the influence of optical path changes etc. due to this can be reduced.

In the above-mentioned embodiment, there is a gap between the glass plate α [present] and the prism plate α, and between the prism plate α and the concave lens (19a
), but in the case of ethylene glycol, it is absorbed into the resin forming the prism plate α and deteriorates the optical properties of the prism plate α. There is a buildup. Therefore 1. It is conceivable to use silicone oil for the tl of ethylene glycol. In this case, in addition to the above embodiment, the spaces on both sides of the glass plate 1 are isolated from each other.

Effects of the Invention According to the present invention described above, the first. and a second transparent material with a second refractive index.
a second transparent material having a temperature coefficient of
The interface is a prism surface, and the ratio of the first refractive index and the second refractive index and the ratio of the first temperature coefficient and the second temperature coefficient are selected to be approximately equal. However, the separation angle hardly changes. Therefore, as in the above-described embodiment, the present invention is suitable for application to a prism plate used in a projection television receiver, for example.

[Brief explanation of drawings]

1 and 3 are block diagrams showing an example of a conventional projection television receiver, respectively, FIG. 2 is a diagram for explaining the example in FIG. 1, and FIG. 4 is a diagram for explaining the example in FIG. 3. FIG. 5 is a configuration diagram showing one embodiment of the present invention, and FIGS. 6 to 8 are diagrams used to explain the prism plate. αQ is a color cathode ray tube, 6 o'clock is a prism plate, (18a)
and (18b) are transparent materials, a is a projection lens, (
2 is a transparent liquid. Fig. 1 Fig. 3 Fig. 2 C Fig. 4 c Fig. 5 Fig. 6 Fig. 7 Fig. 8 E 77 Kumafu: 1; Procedural Amendment 1, Indication of Case 1988 Patent Application No. 233195 2. Title of the invention Prism 3. Name of the person making the amendment (218) Norio Ohga, representative director of Sony Corporation 6. Number of inventions to be increased by the amendment (1) In the specification, the 11th negative 2nd line reads, “... will be made.” ”, change the line and add the following. r~' In the above-described embodiments, the prism plate Q8 can also be obtained by the casting method as shown in the above example. First, as a method of molding the transparent material (18a) constituting the prism plate α mallet, the methods shown in FIG. 9A, FIG. 10A, and 11
A method shown in Figure AJj can be considered. The one shown in FIG. 9A is an injection molding method, and R1/-"
The transparent material of SO LQ is plasticized and molded into a mold Q. After releasing the mold, a transparent material (18a) is obtained as shown in FIG. In addition, the one shown in FIG. 10A is a transfer molding method in which a transparent material (18a') in the form of a bullet is heated, then transferred and filled into a mold θ1), and then molded.
After molding, a 5JC transparent material (18a) as shown in the figure BIC is obtained. =11 The one shown in Figure A is formed by transferring the knee shape of a mold Cl0K made by heating a plate-shaped material (18,;) by compression molding. The transparent material (18a) is released from the mold as shown in Figure B.
is obtained. Next, as a method of molding and gluing the transparent material (18b) onto the transparent material (18a) thus obtained, the methods shown in FIGS. 12A and 13A, B, and CK can be considered. What is shown in FIG. 12 AVC is an injection molding method, in which a transparent material (18a) is inserted into a mold hole, and the transparent material (18a) is inserted into a mold.
A transparent material is injected into the space formed by a) and the mold. After releasing the mold, the transparent materials (18a) and (18b) are glued together as shown in FIG.
Prism plate a~ is obtained. The method shown in FIGS. 13A, B, and CVc is a casting method, in which a transparent material (18b') that is hardened by heat, infrared rays, ultraviolet rays, or other electron beams is prepared, and a prism 4 of the transparent material (18a) is prepared. It is injected (as shown in AVc in the same figure) or sprayed onto the human face, molded as shown in BK in the same figure, and then cured by irradiation with infrared rays, etc., as shown in CVc in the same figure. In the end, as shown in the figure, a prism plate (18) is obtained by gluing the transparent materials (18a) and (18b) together. In Figure 13, X, 1, C35+ is a spacer, (361
is a glass version. (2) Same, line 11m, line 20, ``This is a diagram.'' was corrected to ``Diagrams, Figures 91 to 13 are diagrams for explaining the manufacturing method of IJ Zumashi.'' do. (3) Figures 9 to 13 have been added to the drawings as shown in the attached sheet. Above Figure 9 Figure 12

Claims (1)

[Claims] A first transparent material having a first refractive index and a first temperature coefficient and a second transparent material having a second refractive index and a second temperature coefficient are bonded together, and the interface thereof is with the prism surface. is,
A prism characterized in that the ratio of the first refractive index and the second refractive index and the ratio of the first temperature coefficient and the second temperature coefficient are selected to be approximately equal.