JPS60146584A - Projecting device - Google Patents

Abstract

PURPOSE:To prevent a total reflection by an air layer, and to improve a picture quality of a video projected onto a screen by absorbing an incident light which is made incident on the air layer, just in front of the air layer by a non-reflecting substance. CONSTITUTION:A non-reflecting substance 14 is applied to a contact surface of a silicone gel 10 being a transparent substance and a sealing material 6. When the silicone gel 10 contracts by a drop of an ambient temperature, it is separated from the sealing material 6 in a state that the non-reflecting substance 10 is coupled with the silicone gel 10, and even if light emitted from a phosphor 13 advances in the direction of an air layer 2, it is absorbed by the non-reflecting substance 14 being just in front of the air layer 2. In this way, a total reflection by the air layer 2 is prevented, and a picture quality of a video projected onto a screen is improved. As for this non-reflecting substance 14, a black silicone gel or a black grease and a black clay-like substance are used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a projection device in which a cathode ray tube and a projection lens are optically coupled through a transparent body.

[Background of the invention]

FIG. 1 is an explanatory diagram for explaining interface reflection in a projection device, and FIG. 2 is a sectional view showing a conventional projection device in which interface reflection has been prevented.

In Figures 1 and 2, 1 is a cathode ray tube, 2 is an air layer, 3 is a lens group, 4 is interface reflected light, 5 is a transparent material, and 6
7 is a sealing material, 7 is a lug for mounting the cathode ray tube 1, 8 is a spacing tube, and 9 is a lug for mounting the lens group 6.

As shown in FIG. 1, in a projection device that has a lens group 6 immediately in front of a cathode ray tube 1 and projects and magnifies the image on the cathode ray tube 1, the cathode ray tube 1 and an air layer 2, and the air layer 2 and a lens group 3.
In order to prevent the interface reflected light 4 occurring at each interface, conventionally, as shown in FIG.
A method has been developed for preventing interfacial reflection by enclosing the space between the cathode ray tube 1 and the lens n5 with a sealing material 6, filling the transparent material 5 as a transparent material, and optically coupling the cathode ray tube 1 and the lens n5. Note that the distance between the cathode ray tube 1 and lens group 6 has a great effect on optical performance.
The mounting is kept constant by means of lugs 7.9 and via spacing tubes 8.

FIG. 3 is an explanatory diagram showing a state when silicone gel as a transparent substance contracts in a conventional projection device, and FIG. 4 is an explanatory diagram for explaining the state of total reflection in FIG. 3.

3 and 4, 10 is silicone gel, 1
1 is incident light, 12 is totally reflected light, and 15 is a phosphor.

Conventionally, for example, silicone gel 10 is used as the transparent material 5.
is used.

However, the silicone gel 10 contracts as shown in FIG. 3 when the ambient temperature decreases. Since the distance between the cathode ray tube 1 and the lens group 3 is constant, when the silicone gel 10 shrinks, the adhesive force between the silicone gel 10 and the sealant 6 is weak, so they are separated at this part, and the silicone gel 10 and the sealant 6 are separated. An air layer 2 is created between the two.

As shown in FIG. 4, when a part of the incident light 11 hits this air layer 2, the incident light 11 is totally reflected. The critical angle X in this case is calculated as follows.

Refractive index of silicone gel [1a:: 1. '1 Refractive index of air n1)=1 According to Snell's law, 1Xsio900=1.4Xsinx,°, x = 65.6°, so the critical angle is 456°.

Therefore, the incident light 11 that enters the air layer 2 at an angle greater than 456° is totally reflected. When such total reflection light 12 enters the surface of the screen (not shown), it becomes unnecessary light and causes deterioration in the image quality of the image projected on the screen.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a projection device that eliminates the drawbacks of the prior art described above and can prevent total reflection due to an air layer.

[Summary of the invention]

In order to achieve the above object, in the present invention, a non-reflective material for preventing reflection is provided between the transparent body and the sealing material.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to FIG. 5 and FIG.

FIG. 5 is a sectional view showing one embodiment of the present invention, and FIG.
It is an explanatory view showing a state when silicone gel contracts in the figure.

In FIGS. 5 and 6, 14 is a non-reflective material.

As shown in FIG. 5, silicone gel 10, which is a transparent material,
A non-reflective material 14 is applied to the contact surface between the sealing material 6 and the sealing material 6.

When the silicone gel 10 contracts as the ambient temperature decreases as shown in FIG. 6, the silicone gel 10 is separated from the sealant 6 with the non-reflective material 14 bonded to it.
Even if the light emitted from the phosphor 15 travels toward the air layer 2, it is absorbed by the non-reflective material 14 just in front of the air layer 2.

Therefore, total reflection by the air layer 2 can be prevented.

In addition to black silicone gel, this non-reflective material 14 includes
Possible substances include black grease and black clay-like substances.

For example, in this embodiment, when using black silicone gel as the non-reflective material 14, the black silicone gel is applied to the contact surface of the sealant 6 with the silicone gel 10 in advance and cured, and then the cathode ray tube 1 Assemble the lens 5 and then inject the silicone gel 10 into the area surrounded by the sealant 6 and harden it. If the temperature is lowered in this state, the silicone gel 10 will shrink and the sealing material 6 and the silicone gel 10 will separate, but since the black silicone gel has the property of adhering to the silicone gel 10, the surface of the silicone gel 10 will It is separated from the sealing material 6 while still attached to the surface.

Furthermore, if a release agent such as Teflon is applied in advance to the contact surface of the sealant 6 with the black silicone gel, the black silicone gel can be easily separated from the sealant 6.

In addition, to eliminate the repulsive force acting on the cathode ray tube 1 and the lens group A that occurs when the sealant 6 is compressed, the sealant 6 can be removed after the silicone gel 10 has hardened, and the sealant 6 can be removed without the sealant 6. Since there is still black silicone gel remaining, the light incident on this area is absorbed by the black silicone gel and is not totally reflected.

〔Effect of the invention〕

According to the present invention, since the incident light that is about to enter the air layer can be absorbed by the non-reflective material immediately before the air layer, total reflection by the air layer can be prevented and the image quality of images projected on the screen can be improved. effective.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram to explain interface reflection in a projection device, Figure 2 is a sectional view showing a conventional projection device with interface reflection prevention, and Figure 3 is a diagram showing the shrinkage of silicone gel in a conventional projection device. FIG. 4 is an explanatory diagram for explaining the state of total reflection in FIG. 3. FIG. 5 is a sectional view showing an embodiment of the present invention. FIG. It is an explanatory view showing a state when silicone gel contracts in the figure. 1 CRT, 2: Air layer, 3: Lens group, 4: Interface reflected light, 5: Transparent substance, 6: Sealing material, 10: Silicone gel, 11: Incident light, 12: Totally reflected light, 15: Fluorescence Body, 14: Non-reflective material. No. 3 / Figure 3 % 4

Claims (1)

[Claims] 1) In a projection device in which a transparent material is filled between a cathode ray tube and a projection lens and optically coupled to prevent interfacial reflection, there is an anti-reflection material between the transparent material and a sealing material that surrounds and holds the transparent material. A projection device characterized by being coated with a non-reflective material.