JPH01189288A - Lenticular lens for rear projection type projection television - Google Patents

Abstract

PURPOSE:To maintain a high contrast, a high resolving power, and a high luminance and, simultaneously, to enlarge even a visual angle in a vertical direction by forming many lenticulars to be lined in a direction right-angled to the pitch direction of a black stripe on an emitting surface. CONSTITUTION:First lenticulars 21 to be lined in making the horizontal direction of a screen into the pitch direction are formed at the back side of a lenticular lens 2, simultaneously, projecting parts 22 to be lined in the horizontal direction in the same pitch as the lenticulars 21 are formed at a face side, and black stripes 22a are prepared on the surfaces of the projecting parts 22 by printing, etc. Emitting surfaces 23 are formed by respective voids of respective black stripes 22a, second lenticulars 23a lined in the direction right-angled to the pitch direction of the black stripes 22a are formed on the surfaces of the emit ting surfaces 23 in a large number, and the second lenticulars 23a diffuse a light from the first lenticulars 21 side in the lengthwise direction of the black stripes 22.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a so-called rear projection type projection television in which an image of a projection tube is projected from the back of the screen and the projected image is viewed from the front of the screen. This invention relates to a lenticular lens used in front of a screen to increase the viewing angle and improve screen performance.

[Technical background of the invention and its problems]

Conventionally, in rear-projection type projection TVs such as those mentioned above, in order to be able to see a reasonably bright image even from an oblique direction in front of the screen, the projected light is diffused by a lenticular lens installed in front of the screen, and the output light is adjusted to a predetermined level. I am trying to give a directivity angle.

A large number of lenticules are formed on the back surface of the lenticular lens and are arranged with the horizontal direction of the screen as the pitch direction, and the projection light is mainly diffused by these lenticular lenses. Note that the normal viewing angle is generally about ±40° in the horizontal direction and ±5° in the vertical direction to suit the viewing position.

However, the reason why the directivity angle is large in the horizontal direction and small in the vertical direction as described above is not because it is set to correspond to the normal viewing position, but rather because the lenticular is diffused in the horizontal direction. In the vertical direction, this is due to the fact that a diffusing agent is mixed into the lenticular lens or the exit surface is made rough to achieve diffusion.

In other words, increasing the amount of diffusing agent reduces the light transmittance and causes blurring of the projected image, reducing contrast and resolution, so there is a limit to the amount of diffusing agent that can be mixed into a lenticular lens, and this limit It was not possible to increase the vertical directivity angle.

In addition, if diffusion is performed by mixing a diffusing agent or treating the surface with a rough surface, the diffusion effect will be further increased in the horizontal direction, where sufficient diffusion occurs due to the action of the lenticules, since the diffusion performance of the diffusing agent and the rough surface is isodirectional. This resulted in an inefficient method of imparting diffusion performance to the screen as a whole.

[Purpose of the invention]

The present invention solves the above-mentioned conventional problems in rear projection type projection televisions, and provides a lenticular lens that maintains high contrast, high resolution, and high brightness, and has a wide viewing angle not only in the horizontal direction but also in the vertical direction. The purpose is to

[Summary of the invention]

In a lenticular lens for a rear projection television, the present invention performs horizontal diffusion using the first lenticules on the back side that are aligned in a direction parallel to the pitch direction of the black stripes, and that The second lenticule formed on the exit surface performs vertical diffusion.

〔Example〕

FIG. 1 is a diagram showing a part of a screen using a lenticular lens and a Fresnel lens according to an embodiment of the present invention.
This screen is particularly suitable for use in an l-tube type projection television or a composite projection type projection television in which the emission points of the three tubes of blue, green, and red are set at one location using a dichroic ink mirror or the like. Further, FIG. 2 is a diagram showing the surface of the lenticular lens in detail, and (1)) and fc) in the same figure are A--A in FIG.
The A cross section and the 13-B cross section are shown, respectively.

In the cabinet, 1 is a Fresnel lens placed on the back side of the screen, and 2 is a lenticular lens placed on the front side of the screen.

The back side of the above lenticular lens 2 (Fresnel lens 1
The first lenticules 21 are formed on the side) with the horizontal direction of the screen as the pitch direction, and the first lenticular 21 are formed on the front side (projection light output side).
Projections 22 are formed that are arranged horizontally at the same pitch,
A black stripe 22a is provided on the surface of this protrusion 22.
(The shaded area) is formed by printing or the like.

The width of the black stripes 22a is smaller than the pitch width (P), and an output surface 23 is formed at each gap between each black stripe 22a.

A large number of second lenticules 238 are formed on the surface of the emission surface 23 in a direction perpendicular to the pitch direction of the black stripes 22a (the longitudinal direction of the black stripes 22a), and the second lenticules 238 are arranged in the direction perpendicular to the pitch direction of the black stripes 22a. The light from the lenticular 21 side is diffused in the longitudinal direction of the black stripe 22.

The Fresnel lens l macroscopically converges the projection light from a projection tube (not shown) and projects it as parallel light onto the back surface of the lenticular lens 2.
The projected light is microscopically diffused in the horizontal direction by the lenticular 21 and is emitted from the output surface 23.

At this time, the emitted light is diffused in the longitudinal direction of the black stripe 22a, that is, in the vertical direction of the screen, as shown by the arrow in FIG. viewing angle is expanded.

Note that the directivity angle of vertical diffusion by the lenticule 232 can be set by selecting the shape or radius of curvature of the exit surface of the lenticule 23a.

FIG. 3 is a diagram showing a mold roll used for extrusion molding the lenticular lens 2, and this mold roll 3 has many arcuate grooves formed on its surface as shown in FIG. It is manufactured using a cylindrical metal rod 3'.

That is, the cylindrical metal rod 3' is cut into black stripes 22 by a cutting tool having a cross-sectional shape of the protrusion 22.
Cutting is performed at a pitch of a to form peaks 3a for forming the emission surface 23 and valleys 3b for forming the protrusion 22.

During extrusion molding, the sheet to be molded as a lenticular lens is wound around the mold roll 3 and cooled, and the troughs 3b form the protrusions 22 and the peaks 3.
a forms the exit surface 23 and the second lenticule 23a on the surface thereof. Then, black stripes 22a are formed on the surface of the protrusion 220 by printing or the like.

According to the lenticular lens 2 described above, the external light incident on the exit surface 23 is disturbed at a wide angle by the lenticules 23a formed on the exit surface 23, so that the contrast 1- decreases due to reflection of the external light. can be prevented.

In addition, since there is no need to use a large amount of a diffusing agent, it is possible to obtain high resolution without blurring the projected image, and also to obtain a high-brightness screen because there is no unnecessary diffusion caused by the diffusing agent. be able to.

FIG. 5 is a diagram showing a cross section of the exit side of a lenticular lens used in a projection television using a three-tube horizontal juxtaposition system in which three projection tubes of blue, green, and red are arranged horizontally; The lenticular lens 4 has an aspherical cylindrical lens 41a formed on its exit surface 41 for color shift correction.

The screen in the above embodiment is particularly suitable for use in a one-tube type projection television or a composite projection type projection television, and there is no need to consider color shift as in the case of a three-tube horizontally juxtaposed type.
Aspherical cylindrical lens 413 as shown in the figure
There is no need to form .

Therefore, as the area ratios are shown in FIGS. 2 and 5, the lenticular lens 2 of the embodiment has a smaller area of the exit surface than the conventional lenticular lens 4, that is, the area ratio of the black stripe can be increased. , the contrast of the projected image can be increased compared to conventional ones.

〔Effect of the invention〕

As explained above, according to the lenticular lens of the present invention, the first lenticules on the back surface arranged in a direction parallel to the pitch direction of the black stripes perform diffusion in the horizontal direction, and also perform diffusion in the direction perpendicular to the pitch direction of the black stripes. A lenticular lens that maintains high contrast, high resolution, and high brightness as well as widening the viewing angle not only in the horizontal direction but also in the vertical direction because vertical diffusion is performed by the second lenticules formed side by side on the exit surface. can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a part of a screen using a lenticular lens according to an embodiment of the present invention, Fig. 2 is a diagram showing the surface of a lenticular lens according to an embodiment, and Fig. 3 is a diagram showing a part of a screen using a lenticular lens according to an embodiment. FIG. 4 is a diagram showing a cylindrical metal rod used for manufacturing the mold roll. FIG. 5 is a diagram showing a cross section of the surface of a lenticular lens for a three-tube horizontal juxtaposition system. 2... Lenticular lens, 21... First lenticular, 22a... Black stripe, 23...
...Emission surface, 23a...second lenticular.

Claims (1)

[Claims] A rear projection type projection television in which the gap between the black stripes formed on the front side is used as an exit surface for projection light, and a large number of lenticules arranged in a direction parallel to the pitch direction of the black stripes are formed on the back side. A lenticular lens for a rear projection television, characterized in that, in the lenticular lens, a large number of lenticules are formed on the exit surface in a direction perpendicular to the pitch direction of the black stripes.