JP3310463B2 - Lenticular lens sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called transmission type projection television (hereinafter, television is abbreviated to TV) in which an image is projected onto a screen from the back side and an image transmitted through the screen is observed from the near side. The present invention relates to a lenticular lens sheet for a transmissive screen used in the above.

[0002]

2. Description of the Related Art Hitherto, a lenticular lens has been used for a screen used in a transmission type projection TV in order to widen a viewing angle in a horizontal direction and a vertical direction. In general, a lenticular lens sheet has been used in which diffusible fine particles having a different refractive index from the base material are uniformly mixed in a resin serving as the base material, and the shape of the lenticular lens is provided by an extrusion method or the like. However, in a lenticular lens in which a resin serving as a base material and a diffusing fine particle having a different refractive index from the resin serving as the base material are uniformly mixed, the incident light is incident, and then proceeds while being scattered by the diffusing fine particles. Reached the non-light-emitting portion (black stripe for absorbing external light), and a decrease in contrast and a decrease in light use efficiency were observed.

FIG. 3 shows an enlarged cross-sectional view of a conventional lenticular lens sheet. The light beam incident on the incident side lens 61 of the lenticular lens sheet is diffused in the horizontal and vertical directions by the diffusing fine particles 63 while passing through the lenticular lens sheet, and exits from the exit side surface 62. At this time, a part of the light beam is diffused by the diffusing fine particles, and is absorbed by the external light absorbing layer 64 as shown in FIG.

[0004] The enlarged sectional view of another conventional lenticular lens sheet shown in FIG. 4 (Gazette <br/> see JP-A-3-39944). Incident side lens 7 of lenticular lens sheet
The light rays incident on the light-receiving layer 1 pass through the incident-side lens layer 74 of the lenticular lens sheet and reach the emission-side layer 75. The diffusing fine particles 73 are mixed in the emission side layer, and the light rays are diffused in the horizontal and vertical directions and emitted from the emission side surface 72. Thus, since the configuration of the lenticular lens sheet containing no diffusing fine particles in the entrance-side lens layer, the light in passing through the incident-side lens layer is not to be diffused by the diffusing fine particles, FIG. 3 (e) There is no light that travels to and is absorbed by the external light absorbing layer 64 as seen in (1), and the light utilization efficiency is improved (see JP-A-5-61120).

[0005]

However, in FIG. 4 , the surface of the incident-side lens 71 is mirror-like because no diffusing fine particles are mixed in the incident-side lens layer. For this reason, the reflected light, which has been irregularly reflected by the light diffusing material particles on the incident side lens surface in the past, enters the adjacent incident side lens without being scattered as shown in FIG. However, it was found that the light proceeded through the incident-side lens layer and appeared on the screen as extraordinary light having high intensity.

SUMMARY OF THE INVENTION An object of the present invention is to provide a lenticular lens sheet which solves the above-mentioned conventional problems, has high light use efficiency, and does not generate extraordinary light caused by the incident side lens surface of the lenticular lens. It is in.

[0007]

According to the present invention, there is provided a lenticular lens sheet for solving the above-mentioned problems, comprising: an incident-side lens layer having a plurality of incident-side lenses; And an emission side layer having a plurality of emission surfaces on which the entrance side lens layer and the emission side layer are formed of a substantially transparent resin, and at least the emission side layer has light diffusing fine particles. And the following formulas (I) and (II):

(Equation 4) Is a lenticular lens sheet satisfying the following, and has the following characteristics.

(1) A lenticular lens sheet obtained by extrusion molding , wherein C ₁ ≠ 0 in the formula (I)
And [Delta] n 1 _{= 0} Dea is, a portion of the light diffusing fine particles incident
Present on the side lens surface. ( 2 ) Lenticular lenticular obtained by extrusion molding
And the following formula (II
I) (provided that C ₃ 満 足 0) is satisfied or the following formulas (IV) and (V)

(Equation 5) It has a light scattering layer which satisfies a portion of the light diffusing fine particles enter
Present on the launch lens surface.

[0009]

When the lenticular lens sheet shown in FIG. 4 is used as a transmission type projection screen,
For example, in a projection television in which CRTs of three colors of red, green, and blue are enlarged and projected by a projection lens, a lenticular lens having a high screen gain has four horizontal lines from the front.
0 When the eye from near ° observing the screen while moving to the left and right, is seen to circular extraordinary light in the red, as shown in FIG. 5 is moved over the screen to the left and right, horizontally from the front 50 °
70 when observing the screen while moving the eyes to the left and right from the vicinity °, red as shown in FIG. 6, green, blue vertical strip of abnormal light on defect occurs easily image like moves on the screen to the left and right Was a drawback.

[0010] Figure 7 is intended to extraordinary light in FIG. 5 were analyzed the causes for generating a light beam corresponding to + 10 ° to the incident angle when the light beam from the red CRT lenticular lens sheet shown in FIG. 4 enters FIG. 9 is a diagram showing a result of ray tracing when the light is incident. Most of the light rays incident at + 10 ° are refracted by the incident side lens, travel as indicated by the dotted line in the drawing, and exit from the exit lens. However, some light rays are reflected on the surface of the incident lens according to the angle of inclination of the incident lens at that position, enter the adjacent incident lens, and proceed as shown by the solid line in the figure, and pass through the external light absorbing layer. It was found that the light was emitted from the trapezoidal rising portion for the provision.
Here, when the rays incident on the points A and B on the incident lens were traced, the rays reflected at the point A proceeded as shown by a solid line A ′, and the exit angle was 37 °.
And the light reflected at point B travels as shown by the solid line B ', and emerges at an emission angle of 44 °. In addition, the intensity of these light rays was found to be extremely strong at 0.17, whereas the intensity of normal light rays emitted around 40 ° was 0.4 to 0.5 when the incident light was set to 1. Was. That is, it was found that light reflected at the incident lens surface of the light beam incident on the range of the point A at point B is the cause of the abnormal light shown in FIG.

[0011] Figure 8 is intended to extraordinary light in FIG 6 has analyze the cause of occurrence, 0 ° where the light from the green CRT lenticular lens shown in FIG. 4 corresponds to the angle of incidence upon the incident
FIG. 9 is a diagram showing a result of ray tracing when the light ray is incident. Next, FIG. 9 is a diagram illustrating a result of ray tracing performed when a light beam of −10 ° corresponding to an incident angle when a light beam from a blue CRT is incident on the lenticular lens illustrated in FIG. 4 . It is. A case where a ray of 0 ° corresponding to the incident light from the green CRT is incident and a blue CRT
When obtained by a light ray corresponding -10 ° to the incident light from, as shown in FIG. 7, as in the case where is incident rays at + 10 °, light rays largely refracted by the entrance lens Then, the light advances as indicated by the dotted line, and is emitted from the emission lens. However, some light rays are reflected on the surface of the incident lens according to the angle of inclination of the incident lens at that position, are incident on the adjacent incident lens, travel as shown by the solid line, and are trapezoidal for providing the external light absorbing layer. Out of the rising part of.

By the way, as shown in FIGS. 7 to 9 -
Light rays incident at 10 °, 0 °, and + 10 ° and reflected on the surface of the incident lens have different incident angles, and thus have different exit angles. For example, the reflected light of + 10 ° incident light corresponding to a red ray has an intensity of 0.08 in the direction of 59 ° and an intensity of 0.06 in the direction of 67 ° as shown in C ′ and D ′ (FIG. 7 ). The reflected light of the 0 ° incident light that is emitted and corresponds to the green ray is:
As shown in E ', F', G '(FIG. 8 ), an intensity of 0.09 in the direction of 47 °, an intensity of 0.06 in the direction of 60 °, 69
The reflected light of -10 ° incident light, which is emitted at an intensity of 0.05 in the direction of ° and corresponds to the blue light beam, becomes 0.05 ° in the direction of 62 ° as shown by I ′ and J ′ (FIG. 9 ). , And 0.04 in the direction of 71 °. 50 °,
The intensity of a normal ray emitted in the directions of 60 ° and 70 ° is
When the intensity of the incident light is 1, 0.2 to 0.3, respectively,
From 0.1 to 0.15 and 0.03 to 0.05, it was found that the intensity of the reflected light was extremely high.
In addition, since the emission angle of the reflected light is slightly shifted, when observing the screen from an angle of 45 ° at a distance of 2 m, for example,
Green corresponding to F 'at the center of the screen, blue corresponding to I' 149 mm deep from the center of the screen, red corresponding to C '68 mm before the center of the screen, and 660 m further
It was found that green vertically long strip-shaped extraordinary light corresponding to E 'was observed m in front.

As a result of the above analysis, it has become clear that these extraordinary lights are generated by the reflected light from the incident lens surface, which has not been taken into account. According to the lenticular lens sheet of the present invention, the reflected light on the incident lens surface is reduced, and the occurrence of the abnormal light can be suppressed.

[0014]

The present invention will be described below in detail with reference to examples.

Embodiment 1 In the formula (I), C ₁を 0, Δn ₁ = 0, assuming that abnormal light is reduced without lowering the light use efficiency as much as possible.
The lenticular lens sheet according to the first embodiment will be described. According to this lenticular lens sheet, FIG.
As shown in (2), a part of the light incident on the incident side lens 11 is reflected on the lens surface. However, due to the presence of the diffusing fine particles, irregular reflection in an indeterminate direction occurs as shown in (a), and the light is reflected on the adjacent incident side lens. The incident reflected light is also diffused by the diffusing fine particles existing on the lens surface, so that the intensity of the extraordinary light is reduced. On the other hand, the diffusing fine particles mixed in the incident side lens layer do not have a difference in refractive index from the substrate, so that the principal ray travels through the incident side lens layer without being refracted and is absorbed by the external light absorbing layer. No light is generated. Therefore, the intensity of the extraordinary light can be reduced without lowering the light use efficiency as much as possible.

A specific example of the lenticular lens sheet according to this embodiment will be described. Pitch (p) 0.6
1, the thickness (t) of the incident side lens layer was 0.8 mm, the thickness (t ₁ ) of the incident side lens layer was 0.8 mm, and the thickness (t ₂ ) of the exit side layer was 0.15 mm. A lenticular lens sheet having a structure was manufactured. As the resin for the incident lens layer, for example, a thermoplastic resin such as polymethyl methacrylate is used, and as the diffusing fine particles to be mixed therein, the particle diameter (d ₁ ) is 8 μm, and the difference in refractive index from the base resin (Δn)
₁ ) 3% by weight of 0 fine particles (for example, an organic material) (C
1) Used. Further, as the resin of the emission side layer, for example, a thermoplastic resin such as polymethyl methacrylate is used,
Particle size (d ₂ ) 17 as diffusible fine particles mixed therein
An extruded sheet was prepared using 5% by weight of microparticles (for example, an inorganic material) having a refractive index difference (Δn ₂ ) of 0.07 μm from the base resin. The shape of the lens is given by the following equation (V
In I), the curve is represented as a main curvature C = 3.2 and a conical constant K = −0.45 on the entrance side, and as a main curvature C = −2.9 and a conical constant K = 3.5 on the exit side. .

(Equation 6)

The sheet extruded under the above conditions was printed by a conventional method. Image evaluation was performed on a screen manufactured by combining the lenticular lens sheet manufactured in this manner with a Fresnel lens. As a result, a screen free of extraordinary light was obtained even in the range of 40 ° to 70 ° in the horizontal field of view. Further, when the total light transmittance was measured, it was 87%, and it was a screen with a small light amount loss .

Embodiment 2 The following formula (III) or
(IV) and the formula (V),

(Equation 7) A lenticular lens sheet according to a fifth embodiment provided with a light scattering layer 51 (see FIG. 2 ) satisfying the following conditions will be described.
In this case, as an example of a method of providing a light scattering layer further on the incident side of the incident side lens layer, when forming a lenticular lens sheet by an extrusion method, diffusion before passing through a roll for forming an incident side lens and an output side surface is performed. A method in which a film mixed with a material is supplied and subjected to thermal lamination, a method in which three layers are co-extruded, and a method in which a diffusing material is mixed in the first and third layers, and the like. Here, the incident side diffusion layer satisfies the above formula (III) or the above formulas (IV) and (V)
It is necessary to satisfy Otherwise, when the incident side diffusion layer is Δn ₃ = 0, there is almost no decrease in light use efficiency. However, when Δn ₃ ≠ 0, as the thickness of this layer increases, the light scattered to the external light absorbing portion is reduced. This increases the light use efficiency.

An example of a method for manufacturing a lenticular lens sheet according to this embodiment will be described in more detail. Figure
In order to produce a lenticular lens having the structure shown in FIG. 2 , molding can be performed by a three-layer coextrusion method using an extruder. That is, the resin extruded by the sub-extruder of the extruder was distributed to the light scattering layer and the emission side layer by using a three-layer co-extrusion junction block. Here, the light scattering layer was adjusted so as to be 20 μm thinner than the emission side layer. Light diffusing fine particles were not mixed into the entrance side lens layer by the main extruder. Polymethyl methacrylate is used as the base resin for the light scattering layer and the emission side layer, and the particle diameter (d ₂ = d ₃ ) is 17 μm as the diffusing fine particles mixed therein, and the refractive index difference (Δn ₂ ) from the base resin is used. = Δn ₃ ) 5% by weight of 0.07 fine particles were used. As in Example 1, a pair of lenticular lens-shaped engraved mold rolls were formed without using a surface roughening treatment.

The lenticular lens obtained was used in Example 1.
When the image was evaluated in combination with the Fresnel lens in the same manner as in the above, a screen free of abnormal light was obtained.

Table 1 summarizes the results of image evaluation and the like for the screens specifically described with numerical values in each embodiment.

[Table 1]

[0022]

According to the lenticular lens used in the transmission type screen, no abnormal light is generated due to the reflected light on the incident side lens surface, and a bright image with high light use efficiency can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a lenticular lens sheet according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view of a lenticular lens sheet according to a second embodiment of the present invention.

FIG. 3 is an optical path diagram of a conventional lenticular lens sheet.

FIG. 4 is an optical path diagram of another conventional lenticular lens sheet.

FIG. 5 is a view showing the appearance of extraordinary light when the screen is observed at a horizontal angle of 50 ° to 70 ° when the lenticular lens sheet shown in FIG. 4 is used.

6 is a diagram showing a state of extraordinary light when the screen is observed at a horizontal angle of 40 ° when the lenticular lens sheet shown in FIG. 4 is used.

FIG. 7 is a diagram showing an optical path condition when a light beam having an incident angle of + 10 ° is incident on the lenticular lens sheet shown in FIG. 4 ;

8 is a diagram showing an optical path status when obtained by a light ray incident angle of 0 ° on the lenticular lens sheet shown in FIG.

FIG. 9 is a view showing an optical path condition when a light beam having an incident angle of −10 ° is made incident on the lenticular lens sheet shown in FIG. 4 ;

[Explanation of symbols]

 Reference Signs List 11 incident side lens 12 base material 13 diffusible fine particles 31 incident side lens having light diffusing property 41 roughened exit side layer 51 light scattering layer

Claims (2)

(57) [Claims] 1. An incident side lens layer having a plurality of incident side lenses, and an exit side layer having a plurality of exit surfaces formed with exit surfaces at or near a light condensing point of the incident side lens, The incident-side lens layer and the exit-side layer are formed of a substantially transparent resin, and at least the exit-side layer contains light diffusing fine particles, and the following formulas (I) and (II): Lenticular lens sheet obtained by extrusion molding , wherein in formula (I), C ₁ ≠ 0 and Δ
n 1 _{= 0} der is, part of the light diffusing fine particles are incident lens
A lenticular lens sheet that is present on the surface . 2. An incident-side lens layer having a plurality of incident-side lenses, and an exit-side layer having a plurality of exit surfaces each having an exit surface formed at or near a light condensing point of the incident-side lens, The incident-side lens layer and the exit-side layer are formed of a substantially transparent resin, and at least the exit-side layer contains light-diffusing particles, and the following formulas (I) and (II): And a lenticular lens sheet obtained by extrusion molding , wherein the incident side of the incident side lens layer satisfies the following formula (III) (provided that C _{3 、} 0) or the following formula (III): IV) and (V), It has a light scattering layer which satisfies a portion of the light diffusing fine particles enter
A lenticular lens sheet, which is present on the surface of the projection lens .