JPH06123801A - Light-transmissive plate and device using the same - Google Patents

Abstract

PURPOSE:To reduce ineffective light generated on the light-transmissive plate and in the device. CONSTITUTION:Many saw-tooth-sectioned projection stripes 25 or 31 are juxtaposed on at least one of the top and reverse surfaces of the light-transmissive optical plate where incident light from the top surface is projected from the reverse surface and the light-transmissive plate is so constituted that one of surfaces 25b and 31b constituting the projection stripes 25 and 31 are parallel to refracted light 29 or 32 made incident on the top surface at a specific angle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light-transmitting plate in which incident light from the front surface is emitted from the rear surface, and a large number of ridges having a saw-tooth cross section are juxtaposed on at least one of the front surface and the rear surface. The present invention relates to a device using a plate, and more particularly to a structure for improving light transmission efficiency and preventing ghost.

A Fresnel lens, which is a kind of translucent plate provided with a large number of serrated projections in cross section, has the advantage of being thinner and lighter than a curved lens, and is used in various optical systems. .

In a Fresnel lens having a structure in which a curved surface is replaced with a slant surface having a very small width and the gap between the slant surfaces is connected by an optically ineffective plane, the use efficiency of incident light is lowered by the action of the ineffective surface and a ghost is generated. . Therefore, the translucent plate provided with the Fresnel lens and the large number of serrated cross-sectional projections is desired to have a structure that suppresses the action of the ineffective surface.

[0004]

2. Description of the Related Art FIG. 8 is an explanatory view of a configuration of a conventional Fresnel lens and a ghost reduction method. In FIG. 8 (A), 1
Is a Fresnel lens made of acrylic resin, polycarbonate resin, or the like, 2 to 4 are incident lights that enter the surface of the Fresnel lens 1 from a predetermined direction, 5 is a ridge formed on the surface of the Fresnel lens 1, and 6 is the Fresnel lens 1. It is a ridge formed on the back surface.

A large number of juxtaposed ridges 5 are composed of an incident surface 5a for incident lights 2 to 4 and a vertical surface (ineffective surface) 5b. It is composed of an emission surface 6a from which the refracted light 7 is emitted and a vertical surface (ineffective surface) 6b.

The incident light 2 is incident on the incident surface 5a and is refracted, and is emitted as the emitted light 8 from the emitting surface 6a. Incident light 2
The incident angle of 1 and the outgoing angle of the outgoing light 8 have a constant angular relationship depending on the refractive index of the Fresnel lens 1.

The refracted light 7 of the incident light 3 enters through the incident surface 5a and exits through the exit surface 6a, then re-enters the Fresnel lens 1 through the ineffective surface 6b, and the ineffective light 9 comes from the tip of the adjacent exit surface 6a. Is emitted as. The reactive light 9 and the outgoing light 8 have different outgoing directions.

Incident light 4 enters through the incident surface 5a and is reflected by the ineffective surface 5b to become ineffective light 10 in the Fresnel lens 1. The reactive lights 9 and 10 impair the brightness of the emitted light 8 and act as a factor for generating a ghost.

In FIG. 8B, the light absorption films 11 and 12 are formed on the incident surface 5a and the emission surface 6a as a measure for preventing the above-mentioned action by the ineffective light 9 and 10. The light absorption film 11 on the incident surface 5a is
The incident light 4 is prevented from entering the Fresnel lens 1.
The light absorption film 12 on the emission surface 6a prevents the refracted light 7 of the incident light 3 from re-entering the Fresnel lens 1.

Therefore, although the Fresnel lens 1 having the light absorbing films 11 and 12 formed increases the brightness of the emitted light 8 and prevents ghosts, it absorbs all the incident light 2, 3 and 4. film
The ratio of incident light 2 used without being absorbed by 11,12 is about 50 to 90%.

[0011]

As described above,
The conventional ghost reduction method is a method in which incident light, which becomes invalid light, is absorbed by the light absorption films 11 and 12. Therefore, while it is possible to reduce ghost, 10% or more of the total incident light is not used, especially about 50% is used in the case where the ridge having the ineffective surface is formed on the front surface and the back surface as shown in FIG. There is a problem in that the light efficiency is lowered.

[0012]

FIG. 1 is an explanatory view of the basic constitution of the present invention, in which 21 and 22 are Fresnel lenses (transparent plates) according to the present invention, and 23 are Fresnel lenses (transparent plates) according to the present invention. It is a device using 24.

In FIG. 1 (A), 25 is a Fresnel lens 21.
The ridges with a saw-tooth cross section formed on the surface (surface on the light incident side), 27 and 28 are incident light from a predetermined direction, and the ridges 25 are composed of the light incident surface 25a and the invalid surface 25b. A light absorption film 26 is formed on the surface 25b.

The incident light 27 is incident on the Fresnel lens from the incident surface 24a.
While it is incident on the lens 21 and is refracted in the lens 21 to become refracted light 29 in a predetermined direction, the light absorbing film 25 on the ineffective surface 24b parallel to the refracted light 29
The incident light 28 radiated on is absorbed by the light absorption film 25 and disappears,
Ineffective light will not be generated in the Fresnel lens 21.

In FIG. 1B, 31 is a Fresnel lens 22.
Of the sawtooth shaped cross section formed on the back surface (surface on the light emission side) of the, the refracted light 32 is incident on the Fresnel lens 22 from a predetermined direction on the surface, and the projection 31 is formed on the light emission surface 31a and the invalid surface 31b. Consists of

The ineffective surface 31b is parallel to the refracted light 32. Therefore, the parallel refracted light 32 is emitted from the light emitting surface 31a, and the ineffective surface 31b does not interfere with the refracted light 32, so that the Fresnel lens 22 does not generate ineffective light.

In FIG. 1C, the optical device 23 comprises a Fresnel lens 24 having a ridge 40 formed on the surface thereof, and a flat plate 38 through which transmitted light 36, 37 in a predetermined direction is transmitted. Is composed of a light incident surface (first surface) 40a and an ineffective surface (second surface) 40b.

On the lower surface of the flat plate 38 is a light absorbing film 39 corresponding to the light absorbing film 26 of FIG. 1A, that is, transmitted light 36, 37 from a predetermined direction.
A light absorption film 39 that absorbs the transmitted light 37 that is about to enter the ineffective surface 40b is formed. Then, the transmitted light 36 becomes incident light 27 which is transmitted through the flat plate 38 and is incident on the Fresnel lens 24,
The invalid surface 40b is parallel to the refracted light 29 on which the incident light 27 is incident on the Fresnel lens 24.

Therefore, the Fresnel lens 24 is transmitted through the flat plate 38.
The incident light 27 irradiating the surface of the Fresnel lens 24 enters the Fresnel lens 24 and becomes refracted light 29.
The transmitted light 37 that is incident on is absorbed by the light absorbing film 39 and disappears, so that the ineffective light due to the ineffective surface 40b is not generated in the Fresnel lens 24.

[0020]

In the translucent plate according to the above means, the other surface of the ridge having one surface serving as the light incident surface or the light exit surface is made parallel to the refracted light which is incident on the translucent plate at a predetermined angle and is refracted. A light absorbing film is formed on the other surface.

Therefore, the refracted light in the light-transmitting plate is not irradiated to the other surface, which is 90% in the conventional method using the light absorbing film.
According to the present invention, the utilization efficiency of incident light, which was about 50%,
It will be improved to 95 to 25%.

Further, in a device using a translucent optical plate in which the light incident from the front surface is emitted from the rear surface, the light absorbing film according to the present invention can be used as a light transmissive plate by utilizing the principle of the translucent plate of the present invention. Other than the flat plate, the light utilization efficiency is improved and the light absorption film is easily formed.

[0023]

EXAMPLES Examples in which the present invention is applied to a Fresnel lens will be described below with reference to the drawings.

FIG. 2 is an explanatory view of a Fresnel lens according to the first embodiment of the present invention, FIG. 3 is an explanatory view of a Fresnel lens according to the second embodiment of the present invention, and FIG. 4 is a third embodiment of the present invention. 5 is an explanatory view of a Fresnel lens according to a fourth embodiment of the present invention, FIG. 6 is an explanatory view of an apparatus according to the first embodiment of the present invention, and FIG. 7 is a second view of the present invention.
FIG. 3 is an explanatory view of the device according to the embodiment of FIG.

In FIG. 2, a Fresnel lens (transparent plate) 41 having a flat back surface is formed by arranging a large number of protrusions 25 on the front surface. The ridge 25 includes a light incident surface 25a on which the incident light 27 from a predetermined direction is incident and an ineffective surface 25 parallel to the refracted light 29 of the incident light 27.
The light absorption film 26 formed on the ineffective surface 25b configured by b absorbs the incident light 28 from the same direction as the incident light 27, and
Eliminates the generation of scattered light at the joint between a and the invalid surface 25b.

A Fresnel lens 41 made of acrylic resin, polycarbonate resin, or the like, in which refracted light 29 is emitted from the back surface.
Is the light transmission efficiency (visibility) because the irradiation area of the incident light 27 is expanded with respect to the incident light 27, 28 inclined toward the light incident surface 25a as shown in the figure, and no ineffective light is generated inside. Will be improved and ghost will not occur.

In FIG. 3, a Fresnel lens (transparent plate) 42 having a flat surface has a large number of protrusions 31 arranged in parallel on the back surface. The ridges 31 are formed by refracted light 32 that has entered the surface from a predetermined direction
And an ineffective surface 31b parallel to the refracted light 32.

A Fresnel lens 42 made of acrylic resin, polycarbonate resin or the like, in which refracted light 32 is emitted from the back surface.
Eliminates the ineffective light without using the light absorption film, and all the incident light from the front surface is emitted from the rear surface, so that the light transmission efficiency is improved and the ghost does not occur.

However, if a light absorbing film (not shown) is formed on the invalid surface 31b, the invalid surface 31 may be formed due to a formation error of the protrusion 31 or the like.
The light absorption film absorbs the refracted light 32 radiated to b, and the ineffective surface 31
It is possible to eliminate the ineffective light that is scattered and generated at the junction between b and the exit surface 31a and the ineffective surface 31b.

In FIG. 4, Fresnel lens (transparent plate)
As for 43, a large number of ridges 51 having a saw-tooth cross-section are arranged in parallel on the front surface, and a large number of ridges 52 having a saw-tooth cross-section are arranged on the back surface in the same direction as the ridges 51.

The ridge 51 has the same shape as the conventional ridge 5,
An incident surface 51a on which the incident light 27 from a predetermined direction is incident and a vertical surface (ineffective surface) 51b are formed, and a light absorption film 53 is formed from the tip of the incident surface 51a to the ineffective surface 51b.

The portion formed on the incident surface 51a as a part of the light absorption film 53 absorbs the incident light 28 which is incident on the ineffective surface 51b by the refracted light when the incident light 27 is incident in parallel. The protrusion 52 has the same shape as the protrusion 31, that is, the emission surface 31a and the emission surface 31a.
The refracted light 29 further incident is joined to an ineffective surface 31b parallel to the refracted light 29, and a light absorption film 54 is formed on the ineffective surface 31b.

The Fresnel lens 43, which is made of acrylic resin, polycarbonate resin, or the like, and in which the refracted light 29 is emitted from the emission surface 31a, is absorbed by the light absorption film 53 of the incident light 28 that causes the invalid light (4). All of the refracted light 29 incident and refracted by the incident light 27 is emitted from the emission surface 31a without being disturbed by the ineffective surface 31b.

The light absorbing film 54 absorbs the light irradiating the ineffective surface 31b due to the formation error of the protrusions 52 and eliminates the ineffective light scattered and generated at the joint between the emitting surface 31a and the ineffective surface 31b. effective.

In FIG. 5, Fresnel lens (transparent plate)
Reference numeral 44 is a configuration in which the Fresnel lens 41 and the Fresnel lens 42 described above are integrated, and a large number of serrated ridges having a cross-sectional sawtooth shape are formed on the surface.
25 are juxtaposed, and a large number of projections 31 having a saw-tooth cross section are juxtaposed on the back surface in the same direction as the projections 25.

Therefore, the incident light 28 applied to the light absorbing film 26 is absorbed by the light absorbing film 26, but the incident light 27 enters the Fresnel lens 44 from the incident surface 25a, and all the refracted light 29 is invalid. The light is emitted from the emission surface 31a without being disturbed by the surface 31b.

Therefore, the Fresnel lens 44 has both the characteristics of the Fresnel lens 41 and the Fresnel lens 42, and further, by forming a light absorbing film on the invalid surface 31b, the invalid surface 31b is formed due to the formation error of the protrusion 31 and the like. Refraction light 32
It is possible to eliminate the ineffective light that is absorbed by the light absorption film and is scattered at the joints between the ineffective surface 31b and the emission surface 31a and the ineffective surface 31b.

In FIG. 6, the device 45 includes a light absorbing film 53 and a light absorbing film 54.
The transparent flat plate 55 is made to face the surface of the Fresnel lens 43, and the light incident surface (first surface) 51a and the vertical invalid surface are formed on the surface of the Fresnel lens 43 facing the flat plate 55.
(Second surface) A large number of ridges 51 formed of 51b are provided, and a large number of ridges 31 are provided on the back surface of the Fresnel lens 43.

The flat plate 55 is a surface light source or a display panel that emits incident light 56 toward the Fresnel lens 43, and is a flat plate.
A light-absorbing film 57 corresponding to the light-absorbing film 53 is formed on the back surface of the light-absorbing film 53, and the transmitted light 58 that enters the Fresnel lens 43 and generates the ineffective light 10 is formed as shown by the chain line in the figure. Absorbs.

Incident light that is not disturbed by the light absorption film 57
56 is incident on the Fresnel lens 43, and its refracted light 29 does not generate ineffective light in the Fresnel lens 43 and exit surface 31a.
It comes out more.

Since the light absorbing film 57 is formed on the flat back surface of the flat plate 55, it is easier to form the light absorbing film 53 on the ineffective surface 51b of the ridge 51. In FIG. 7, reference numeral 61 is a projection device, 62 is a surface light source, 63 is a transmissive liquid crystal display panel for forming a desired image in a pattern, and 64 is a lens group in which a large number of gradient index lenses are arranged. The image light 65 emitted from the lens group 64 is magnified by the Fresnel concave lens 66, becomes parallel light by the Fresnel convex lens 67, and is projected on the screen 68.

However, the Fresnel concave lens 66 and the Fresnel convex lens 67 are the lenses 41, 42 or 43 of the present invention or
44 is used, or the device 45 is used, whereby the ineffective rate of the emitted light of the light source 62 is reduced to about 1/2 of the conventional one, and the projected image on the screen 68 is sharpened.

In each of the above-described embodiments, the present invention is applied to the Fresnel lens having the annular protrusion. However, the present invention is not limited to a Fresnel lens, and is applied to an antiglare translucent plate in which a large number of ridges are arranged in a straight line for use as a front cover of a display panel, for example, to make an image on the display panel clear. Turn into.

[0044]

As described above, the light transmitting plate and the device using the light transmitting plate according to the present invention can reduce the conventional ineffective light to about 1/2, and improve the visibility of the optical image. There is an improved effect.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a basic configuration of the present invention.

FIG. 2 is an explanatory diagram of a Fresnel lens according to a first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a Fresnel lens according to a second embodiment of the present invention.

FIG. 4 is an explanatory diagram of a Fresnel lens according to a third embodiment of the present invention.

FIG. 5 is an explanatory diagram of a Fresnel lens according to a fourth embodiment of the present invention.

FIG. 6 is an explanatory diagram of a device according to a first embodiment of the present invention.

FIG. 7 is an explanatory diagram of an apparatus according to a second embodiment of the present invention.

FIG. 8 is an explanatory diagram of a configuration of a conventional Fresnel lens and a ghost reduction method.

[Explanation of symbols]

21,22,24,41,42,43,44,64,67 are Fresnel lenses (transparent plates) 23,45,61 are devices using transparent plates 25,31,40,51,52 are sawtooth cross sections The ridges 25a, 40a, 51a of the shape are light-incident surfaces of the ridges 25b, 31b, 40b are parallel to refracted light.The ridge-forming surfaces 26, 39, 53, 54, 57 are light absorbing films 27, 56 are transparent. Incident light 28 that enters the plate (Fresnel lens) is incident light that does not enter the transparent plate (Fresnel lens) 29,32 is refracted light inside the transparent plate (Fresnel lens) 36,37,58 is transmitted light 38,55 Is a transparent plate

Claims (4)

[Claims] 1. In a translucent optical plate in which incident light from the front surface is emitted from the rear surface, a large number of ridges (25, 31) having a sawtooth-shaped cross section are juxtaposed on at least one of the front surface and the rear surface, One surface (25a, 31a) forming the ridge (25, 31) is a light incident surface or a light emitting surface, and the other surface (25b, 31b) forming the ridge (25, 31) is A transparent plate which is parallel to refracted light (29, 32) incident on the surface at a predetermined angle. 2. A translucent optical plate in which incident light from the front surface is emitted from the rear surface, and a large number of cross sections of which one surface is an incident surface (51a) on which incident light (27) at a predetermined angle is incident. The sawtooth-shaped first ridges (25, 51) are arranged side by side, and on the back surface thereof, a surface (31b) parallel to the refracted light (29) of the incident light (27) and the refracted light
A translucent plate, characterized in that a large number of second protrusions (31, 52) having a saw-toothed cross section, which are composed of an emission surface (31a) from which (29) is emitted, are arranged in parallel. 3. The ridge (25,31) according to claim 1 or the second ridge (31,52) according to claim 2, wherein the refracted light (2
The transparent plate according to claim 1 or 2, wherein a surface (25b, 31b) parallel to 9,32) is provided with a light absorbing film (26, 54). 4. A first surface (40a, 51a) on which incident light (27, 56) at a predetermined angle is incident and a second surface (40b, 40b, 51a) intersecting the incident surface (40a, 51a) at an appropriate angle. The transparent plate (38, 55) faces the surface of the transparent plate (24, 43) in which a large number of ridges (40, 51) having a sawtooth cross section are arranged in parallel, and the transparent plate (38, 55) is formed. Sex plate (38,55)
In the device in which the incident light (27,56) transmitted through the transparent plate (24,43) is transmitted, the transparent flat plate (38,55) for emitting the incident light (27,56) is , The transparent plate (38,55) which is transmitted through the transparent plate (38,55) in the same direction as the incident light (27,56) and is about to enter the second surface (40b, 51b). ) Transmitted light (37,5
8), from the same direction as the incident light (27, 56), the first surface (40a, 5a
The light absorption film (39) which blocks the transmitted light (37, 58) of the transparent flat plate (38, 55) which is incident on the first surface (1a) and is refracted to irradiate the second surface (40b, 51b). , 57) is formed, and a device using a translucent plate.