JPH0387819A - Translucent type projection screen - Google Patents

Abstract

PURPOSE:To remove upper and lower external light and to obtain a high contrast by providing an interfacial lens surface between a light-incidence-side and a light-projection-side lens surface, providing a lenticular lens which is specified in their direction, and forming a light absorbing layer on the light projection surface. CONSTITUTION:A lenticular lens 14a is formed perpendicularly on the lens surface 14 of the incidence-side sheet part 11 of the transmission type projection screen 1 and a lenticular lens 15 is formed perpendicularly on the lens surface 15 of the projection-side sheet part 12. The interfacial lens surface 13 is provided between both the sheet parts 11 and 12 and a lenticular lens 13a is formed in parallel to them; and the projection-side lens surface 15 has its projection surface arranged nearby the focus of the interfacial lens surface 13 and the light absorbing layer 16 is provided to the light nonprojection part of the projection surface. Consequently, the vertical external light is removed effectively and the high-contrast screen is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a transmission type projection screen used in a projection television set, etc., and in particular, the refractive index becomes discontinuous at an interface inside the screen, and the interface This relates to a transmission type projection screen having a lens shape.

[Conventional technology]

A transmissive projection screen has the original function of diffusing the light projected from the light source side to the viewing side, and at the same time, when projecting with a color TV projector whose brightness is not very high, the transmissive projection screen has the function of diffusing the light projected from the light source side to the viewing side. is reflected on the screen surface, lowering the contrast of the projected image and impairing visibility, so it is required to reduce the reflection of external light.

Conventionally, this type of transmission projection screen has been made by combining multiple lens sheets, including lenticular lens sheets arranged so that the travel lines of the lenticular lenses (the axes of the cylindrical lenses) are parallel. It is known that a light absorbing layer (black stripe) for preventing reflection of external light is provided on a non-light emitting part of a light emitting surface of a lens sheet disposed closest to the observation side.

Such a transmissive projection screen uses a combination of multiple lens sheets, so when projecting with a color TV projector that does not have very high brightness as mentioned above, the brightness decreases as the number of lens sheets increases. There was a problem.

In order to solve this problem, Utility Model Application Publication No. 64-40836 ``Rear Projection Screen'' proposes ``a screen with two transparent sheets with different optical refractive indexes attached to each other at a predetermined interval on the front surface of the back of the screen. In addition to providing black stripes, a large number of condensing lens surfaces are provided on the boundary surfaces of the transparent sheets on the front and back sides of the screen body to condense incident light from the back side of the screen toward the light output area between each black stripe on the front side of the screen body. A configuration is disclosed in which "a continuous series of ".

[Problem to be solved by the invention]

However, in the screen disclosed in Utility Model Application Publication No. 64-40836, the light absorption layer is simply provided in a vertical line, so external light incident from above and below is reflected. There is a problem in that the effect of preventing this is small and the contrast of the projected image is reduced.

An object of the present invention is to provide a transmissive projection screen that increases the ratio of the light absorption layer to the light exit surface, effectively prevents reflection of external light from above and below, and reduces the decrease in contrast of the projected image. It is.

[Means to solve the problem]

In order to solve the above problems, the transmission type projection screen according to the present invention is a transmission type projection screen in which a light entrance side sheet part and a light output side sheet part having different refractive indexes are provided in close contact at an interface having a lens shape. , an interface lens surface on which a plurality of interfacial lenticular lenses are arranged such that the running lines are parallel to the interface between the two sheet parts, and the interfacial lenticular lenses and the running lines are on the light input side of the light input side sheet part. A light-input side lenticular lens is arranged such that the light-input-side lens surface on which the light-input-side lenticular lens is arranged orthogonally intersects, and the light-output side lenticular lens is arranged on the light-emission side of the light-output-side sheet part so that a running line is parallel or perpendicular to the interface lenticular lens. and a light-emitting side lens surface.

In this case, the light-emitting surface of the light-emitting side lens surface can be provided near the focal point of the interface lenticular lens, and a light absorption layer can be provided on the non-light-emitting portion of the light-emitting surface.

Further, the light-emitting side lens surface is provided with a convex portion on the non-light-emitting portion of the light-emitting surface, and a light absorption layer can be provided on the convex portion.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings and the like.

FIG. 1 is a perspective view schematically showing an embodiment of a transmission type projection screen according to the present invention, FIG. 2 is a sectional view showing a part of the same embodiment screen with an optical path attached, and FIG. 3 FIG. 2 is a diagram showing an optical system of a projection TV using the same embodiment screen.

The transmission projection screen 1 consists of two layers: a light-inlet side sheet part 11 and a light-output side sheet part 12, and each sheet part 11.
12 have different refractive indexes.
．． An interface lens surface 13 is formed at the interface 12. The interface lens surface 13 is an interface lenticular lens 13
A is formed in large numbers parallel to each other, the traveling line thereof is in the horizontal direction, and each interface lenticular lens 13a is arranged so as to be convex toward the light incident side.

On the light incident side of the light incident side sheet portion 11, a light incident side lens surface 14 is provided.
is formed. The light entrance side lens surface 14 has a large number of light entrance side lenticular lenses 14a formed in parallel, and is arranged so that the running line thereof is in the vertical direction.

A light-emitting side lens surface 15 is provided on the light-emitting side of the light-emitting side sheet portion 12.
is formed. The light-emitting side lens surface 15 has a large number of light-emitting side lenticular lenses 15a formed in parallel, and is arranged so that the running line thereof is in the vertical direction.

Here, each lenticular lens 13a, 14a, 15
The shape and arrangement of a will be further explained.

The interface lenticular lens 13a is attached to the light entrance side sheet part I.
An ellipse with an eccentricity ε equal to the ratio of the refractive index n1 of I and the refractive index n of the light-emitting sheet portion 12, that is, when the major axis of the ellipse is a and the minor axis is b, "" (1-(b /a)”
) + z * Cod n, /n weight ... By making the interface lenticular lens 13
As shown in Figure 2, the light incident parallel to the optical axis of a is
can be focused with almost no aberration.

For example, as for the refractive index of each sheet part 11, 12, if acrylic resin is used as the base material of the light entrance side sheet part 11 and polystyrene resin is used as the base material of the light output side sheet part 12, the light entrance side The refractive index of is 1.49. The refractive index on the light exit side is 1.60. Therefore, the ratio of refractive indices is n+
/nt -1,49/ 1-60-0.931.

At this time, if an ellipse or a part thereof is used as the interface lenticular lens 13a, for example, the ratio of the major axis a to the minor axis is t:o, ae4, then the eccentricity is c, g-(1(
0,18210,5)”)””-〇, becomes 931.

With this setting, the light that enters the interface lenticular lens 13a in parallel is focused at the focal point of the ellipse forming the shape of the interface lenticular lens 13a, as shown in FIG.

Further, if the interface lenticular lens 13a is an ellipse as described above, and the major axis of the ellipse is 1, the distance between the focal point and the apex of the ellipse is 1.93. Therefore, if the light-emitting side lenticular lens 15a is arranged so that the vicinity of the focal point of this ellipse becomes the light-emitting surface, a part of the light-emitting surface in the vertical direction can be made into a non-light-emitting part. Therefore, by providing the light absorbing layer 16 also in the horizontal direction in the non-light emitting portion of the light emitting side lenticular lens 15a, the light absorbing layer 16 can be provided in a matrix.

Light entrance side and light exit side lenticular lenses 14a, 15
Although the shape and characteristics of a are not particularly limited, the distance between the light exit surface and the interface may be set so that the light exit surface of the light exit side lenticular lens 15a is near the focal point of the interface lenticular lens 13a.

Conversely, when the thickness of the screen is fixed, the pitch of the interface lenticular lenses 13a may be set so that the distance between the light-emitting side lens surface 15 and the interface lens surface 13 is smaller than the thickness of the screen.

The material for manufacturing the transmission projection screen 1 may be any material as long as it is transparent and can be shaped into a sheet-like bottom, such as acrylic resin such as polymethyl methacrylate or polyester resin.

Resins such as cellulose resins, polyvinyl chloride resins, polystyrene resins, and polycarbonate resins, or glass are preferably used.

In addition, the transmission projection screen l can be formed by forming the bottom shape by coextrusion using the above-mentioned resin, or by using a casting method, an aging molding method, a radiation curing method, etc. ．． 1 in the shape of one of the light-emitting side sheet parts 12
After making the bottom shape using one resin and glass, we used another resin with a different refractive index.

Glass can be used to bottom the other shape.

The transmission type projection screen 1 can be used in a projector TV having the configuration as shown in FIG. 0 projected on screen 1
Normally, the projector 3 has green light G at its center, and light sources for blue light B and red light R are arranged on the left and right sides thereof.

Next, a specific manufacturing example corresponding to the first example will be further explained.

First, the light output side sheet part 12 was molded on the interface side of the light input side sheet part 11 using a polystyrene resin having a refractive index of 1.60 by thermoforming.

Next, the light entrance side sheet portion 11 was molded using an acrylic resin with a refractive index of 1.49 by an ionizing radiation curing method.

At this time, the interface lens surface 13 is a part of an ellipse with a major axis of 0.5 mm, and the ratio of the major axis a to the minor axis a is 1:0.3.
A large number of interfacial lenticular lenses 13a each having a width of 0.3 mm are formed in the horizontal direction. Therefore, the formula ■ is a −(1−(0,182
10,5) ” ) ”” = 0.931.

Further, on the light entrance side lens surface 14, a large number of light entrance side lenticular lenses 14a each having a width of 0.9 mm are vertically formed using a part of a circle with a radius of 0.8 mm.

Therefore, the light input side sheet part 11 and the light output side sheet part 12
The ratio of the refractive index is n+/nt-acrylic resin/polystyrene resin-1,49/1.60-0.931.

A portion of a circle with a radius of 0.6 mm is used for the light-emitting side lens surface 15, and a plurality of light-emitting side lenticular lenses 15a each having a width of 0.9 mm are formed in the vertical direction. As a result, the distance from the valley of the light entrance side lens surface 14 to the apex of the light exit side lens surface 15 is 1.0 mm.

On the light-emitting side lens surface 15, a light absorption layer 16 having a width of 0.6 mm is formed in the valley of the light-emitting side lenticular lens 15a. Furthermore, by setting the distance between the apex of the interface lenticular lens 13a and the apex of the light-emitting side lenticular lens 15a to approximately 0.96 mm, the light-emitting side lens surface 1
60% of the light emitting surface of No. 5 could be made into a non-light emitting part. As a result, the light absorbing layer 16 can be formed even on the peaks of the non-light emitting part of the light emitting side lenticular lens 15a, so the ratio of the light absorbing layer 16 can be adjusted horizontally and vertically to
We were able to reduce it to 6%.

4 to 7 are perspective views schematically showing other embodiments of the transmission type projection screen according to the present invention.

In each of the embodiments described below, parts that perform the same functions as those in the embodiment shown in FIG. 1 are given the same suffixes.

In the transmission type projection screen 4 shown in FIG. 4, the traveling line of the interface lenticular lens 43a formed on the interface lens surface 43 is arranged in the vertical direction, and the light entrance side lenticular lens formed on the light entrance side lens surface 44 is arranged vertically. The running line of the light emitting side lenticular lens 44a is arranged in the horizontal direction, and the running line of the light exiting side lenticular lens 45a formed on the light exiting side lens surface 45 is arranged in the vertical direction.

This transmissive projection screen 4 can be suitably used when the vertical viewing angle is desired to be larger than the horizontal viewing angle.

The transmission type projection screen 5 shown in FIG. 5 has a band-shaped convex portion 55b formed in the valley portion of the light-emitting side lenticular lens 55a on the light-emitting side lens surface 55. Light absorbing layer 5
6 was formed.

In this transmission type projection screen 5, it is easy to form the light absorption layer 56, and if the horizontal portion of the light absorption layer 56 is also made convex, manufacturing can be made easier.

In the transmission type projection screen 6 shown in FIG. 6, the running line of the interface lenticular lens 63a formed on the interface lens surface 63 is arranged in the horizontal direction, and the light entrance side lenticular lens formed on the light entrance side lens surface 64 is arranged horizontally. The running line of 64a is arranged in the vertical direction, and the running line of the light-emitting side lenticular lens 65a formed on the light-emitting side lens surface 65 is arranged in the horizontal direction.

By using this transmissive projection screen 6 when the three-tube light source is arranged vertically, color shift can be corrected and an image with good color balance can be obtained.

In the transmission type projection screen 7 shown in FIG. 7, an interface lenticular lens 73a formed on an interface lens surface 73 is arranged so as to be convex toward the light output side. In this case, the refractive index of the light entrance side sheet part 71 is set high, and the refractive index of the light exit side sheet part 72 is set low.

This transmission type projection screen 7 is similar in application to the one shown in FIG.
After producing the light input side sheet part 71, the light output side sheet part 7 is manufactured.
It is reversed to make 2.

The present invention is not limited to the embodiments described in detail above, and various modifications such as replacement of elements or partial changes in each embodiment are possible.

For example, the convex portion of the non-light emitting portion can be similarly provided in other screens than those shown in FIG. 5, and the arrangement in which the interface lens surface is convex toward the viewing side can also be applied to screens other than those shown in FIG. 7.

〔Effect of the invention〕

As explained in detail above, according to the present invention, it is possible to form a light absorption layer also in the horizontal direction, so that the influence of external light from above and below can be effectively removed, so that a high-contrast transmission projection screen can be formed. I was able to realize this.

In other words, by specifying the relationship between the refractive index (ratio) and the lens shape and improving the light gathering ability, it is possible to increase the formation area of the light absorption layer compared to the conventional example, and the contrast can be improved. I was able to improve it significantly.

[Brief explanation of drawings]

FIG. 1 is a perspective view schematically showing an embodiment of a transmission type projection screen according to the present invention, FIG. 2 is a sectional view showing a part of the same embodiment screen with an optical path attached, and FIG. 3 FIG. 2 is a diagram showing an optical system of a projection TV using the same embodiment screen. 4 to 7 are perspective views schematically showing other embodiments of the transmission type projection screen according to the present invention. Engineering: Transmissive projection screen 11... Light entrance side sheet part 12... Light exit side sheet part 13... Interface lens surface 14... Light entrance side lens surface 15... Light exit side lens surface 16 ...Light absorption layer 2...Optical path 3...Projector

Claims (3)

[Claims] (1) In a transmissive projection screen in which a light input side sheet part and a light output side sheet part with different refractive indexes are provided in close contact at a lens-shaped interface, the running line is parallel to the interface between the two sheet parts. an interface lens surface on which a plurality of interface lenticular lenses are arranged, and a light input side lenticular lens arranged on the light input side of the light input side sheet part so that the traveling line is orthogonal to the interface lenticular lens. A light-emitting lens surface comprising: a side lens surface; and a light-emitting side lens surface in which a light-emitting side lenticular lens is arranged on the light-emitting side of the light-emitting side sheet part so that a traveling line is parallel or orthogonal to the interface lenticular lens. shape projection screen. (2) The light-emitting side lens surface is characterized in that the light-emitting surface is provided near the focal point of the interface lenticular lens, and a light absorption layer is provided on the non-light-emitting portion of the light-emitting surface. ) Transmissive projection screen. (3) Claim (1) characterized in that the light-emitting side lens surface is provided with a convex portion on a non-light-emitting portion of the light-emitting surface, and a light absorption layer is provided on the convex portion. Or a transmission type projection screen according to claim (2).