JPH1048752A - Lenticular sheet for transmission type screen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an invisible state of a screen because of decrease in brightness of the screen depending on the observation direction by specifying the numerical aperture which is determined by the pitch of convex cylindrical lenses, thickness of the lens from the top of the convex of the lens to the opposite flat surface, and width and thickness of a stripe light-shielding pattern formed on the flat surface. SOLUTION: This lenticular sheet which constitutes a transmission type screen in combination with a Fresnel lens sheet has a lens part where convex cylindrical lenses are arranged at a pitch P. The sheet has thickness D from the top of the convex of the cylindrical lens to the flat face opposite to the lens part, and on the flat face, a stripe light-shielding pattern having width P' and thickness D' is formed in the position corresponding to the non-focused part of each cylindrical lens. The numerical aperture defined by (θ-θ')/θ is controlled to >90%, wherein θ=tan<-1> (P-P')/2D} and θ'=tan<-1> (P-P')/2(D+D ')}.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lenticular sheet which, when combined with a Fresnel lens sheet, constitutes a transmission screen used in a liquid crystal projection television.

[0002]

2. Description of the Related Art A transmissive screen generally comprises a combination of a Fresnel lens sheet and a lenticular sheet. As shown in FIG. 1, the lenticular sheet has a convex cylindrical lens surface formed on both surfaces and a single surface (for image light). A projection is formed at the boundary between the cylindrical lenses on the emission side, and a light-shielding layer (light-absorbing black stripe; hereinafter, referred to as BS = black stripe) is formed above the projection. General. The convex cylindrical lens surface is formed on the front and back,
This is because, when the projector (light source) is a three-tube type CRT system, it is necessary to correct the deviation of three colors by the lens on the incident side.

[0003] In the above configuration, when observing obliquely, the observation optical path is blocked by the projections, so that the entire surface of the aperture through which the image light passes can be seen when obliquely observed. No, the screen feels dark. In addition, even if the lenticular sheet has a convex cylindrical lens surface formed only on one side, if the BS is formed on the upper part of the protrusion, the screen will look dark similarly when viewed obliquely. . (See Fig. 2)

After a synthetic resin film containing a light absorbing agent is integrated with the flat surface on the opposite side (observation side) of the lenticular sheet from the cylindrical lens surface, the light transmitting portion of the film is removed. And a strong and uniform thickness of B
A proposal for forming S is known from JP-A-60-17434.

In the proposal according to the above publication, the thickness of the film is assumed to be 0.1 to 0.3 mm. However, as described later, a fine pitch of 0.3 mm or less is required. The cylindrical lens
The thickness is a height corresponding to the above-mentioned protrusion.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lenticular sheet for a transmissive screen in which the brightness of the screen is not reduced due to the viewing direction. In particular, an object of the present invention is to provide the above-mentioned lenticular sheet even for a lenticular in which cylindrical lenses are juxtaposed at a fine pitch.

[0007]

According to the present invention, there is provided a lenticular sheet constituting a transmission type screen in combination with a Fresnel lens sheet, having a lens portion in which convex cylindrical lenses are juxtaposed at a pitch P. The flat surface of the lenticular sheet having a thickness D from the top of the convex portion to the flat surface on the opposite side of the lens portion has a width P ′ and a thickness at a position corresponding to the non-light-collecting portion of each cylindrical lens. When BS is formed in D ', the aperture ratio shown below is 90% or more. (See FIG. 6) θ = tan ⁻¹ {(PP ′) / 2D} θ ′ = tan ⁻¹ {(PP ′) / 2 (D + D ′)} aperture ratio = (θ−θ ′) / θ

In recent years, liquid crystal projection televisions have become widespread, and a transmission screen for observing the image has been demanded. Since the number of pixels of liquid crystal projectors has increased from hundreds of thousands of pixels to more than one million pixels with the increase in definition of video image quality, fine pitch of cylindrical lenses is also required for lenticular sheets. I have. The fine pitch reduces moire phenomenon caused by the periodicity of the pixels of the liquid crystal projector and the periodicity of the cylindrical lens. Specifically, a fine pitch of 0.3 mm or less is demanded from the current 0.7 mm.

The lenticular sheet is currently obtained by press molding a transparent thermoplastic resin sheet or by performing double-side molding at the same time as melt-extrusion. According to the method, it is very difficult to make the above fine pitch. The reason for this is that the temperature is non-uniform at the time of cooling after thermoforming, and the molded product is warped or the heat shrinkage is non-uniform.

As a manufacturing method suitable for molding a fine pitch lens sheet, various molding methods using a resin that is cured by irradiation with radiation such as ultraviolet rays or electron beams (hereinafter referred to as radiation curable resin) are used. Methods are known. A lenticular sheet with a fine pitch is suitable for a transmission screen for observation of a high-definition and high-quality liquid crystal projection television, and it is not necessary to have lens portions on both sides.
It is necessary to take measures to reduce the brightness of the screen.

According to a third aspect of the present invention, there is provided a transparent support on one side,
The cured product of the radiation-curable resin forms a lens portion in which convex cylindrical lenses are juxtaposed at a pitch of 0.3 mm or less, and a flat surface on the opposite side of the support is provided with a non-cylindrical lens of each cylindrical lens. In a case where the BS is formed at a position corresponding to the light-collecting portion, the above-mentioned aperture ratio is 90% or more.

Particularly, regardless of the thickness of the lenticular sheet and the lens pitch, the thickness of the BS is 10 μm.
The following are preferred.

<Operation> Due to the aperture ratio being 90% or more (the height of the BS being 10% or less of the lens thickness), even if the screen is observed from all directions, the observation optical path is blocked. In addition, since the entire surface of the opening through which the image light is transmitted can be seen, the screen feels bright. (Claims 1 and 2)

By using an ultraviolet (electron beam) curable resin, it is possible to make a fine pitch which cannot be realized by a molded article made of a thermoplastic resin, and to produce a fine pitch lenticular sheet having a minimum pitch of 50 μm. Even in the case of the lenticular sheet, by setting the thickness of the BS to 10 μm or less, the brightness of the image light does not decrease even when the viewpoint moves in the left-right direction, and the screen becomes brighter. felt. (Claim 4)

By forming the diffusion layer on the flat surface on the side opposite to the lens of the lenticular sheet, the viewing angle at the time of observation can be expanded not only in the left and right directions but also in the vertical direction.
(Claims 5 and 6) The diffusion layer is a diffusion film in which an inorganic powder such as SiO ₂ , Al ₂ O ₃ , CaCO ₃ is kneaded, or a diffusion coating in which the powder is mixed with a binder to form a paint. It is formed by laminating a film on the surface of a lenticular sheet.

A structure in which a film having an antistatic function or an antireflection function is laminated on the diffusion layer.
By setting 8), each function is exhibited when the lenticular sheet is used, and at the same time, it plays a role of protecting the diffusion layer.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a lenticular sheet made of a cured product of an ultraviolet curable resin will be described below with reference to FIG. 3, but the present invention is not limited to this, and a thermoplastic resin sheet is not limited thereto. The same applies to the case of a lenticular sheet formed by press molding.

The support film 1 is preferably a transparent resin film having a UV-transmitting property, and more preferably has been subjected to a UV-curable resin easy-adhesion treatment on the side where the lens portion is formed. Materials include polyethylene terephthalate (PET), polycarbonate (P
C), polyvinyl chloride (PVC) and the like are used.

The method of applying the ultraviolet curable resin is not particularly limited, but an application method such as a doctor blade or a die coat is preferable. The thickness of the UV curable resin applied to one side of the support film 1 varies depending on the shape of the lenticular lens to be formed.
mm is appropriate. Note that the coating thickness can be adjusted by the viscosity of the resin, the feed speed of the support film, and the like.

A lenticular shape is transferred onto the ultraviolet-curable resin layer of the support film with a lenticular molding stamper (not shown) at a lens pitch of 0.3 mm or less, and the resin is cured by irradiating ultraviolet rays. Let it.

Next, on the non-lens side of the support film 1 on which the lenticular lens 2 made of a cured product of an ultraviolet curable resin is formed, BS3 is formed on the non-light-collecting portion of each unit lens.

A method of forming a light-shielding pattern at a position corresponding to a boundary portion of a fine-pitch cylindrical lens is described in Japanese Patent Application Laid-Open No. Sho 59-121033 and Japanese Patent Application No. Hei.
No. -17482. The above proposal utilizes the presence or absence of adhesiveness between the exposed portion and the non-exposed portion of the photosensitive resin, and exposes the photosensitive resin layer formed on the back surface to the adhesive portion (non-exposed portion) by exposure from the lens portion side. The light-collecting portion is subjected to a light-shielding process.

In the present invention, the BS is formed on the flat surface of the lenticular sheet by utilizing the principle proposed above. A typical example of a photosensitive resin film in which the exposed portion becomes non-adhesive due to the reaction and the non-exposed portion retains the tackiness is a chromane film (trade name; manufactured by DuPont).

After laminating a chromin film on the opposite side of the support film 1 from the lens, and irradiating ultraviolet rays from the lens side, a non-light-collecting portion corresponding to a light-collecting portion and a non-light-collecting portion based on the light-collecting action of the lenticular lens is formed. The adhesive portion / adhesive portion is formed on an ultraviolet-sensitive resin film, and a black transfer layer is transferred only to the adhesive portion to form BS3. For the pressure transfer of BS3, for example, a chrominance ink foil (trade name; manufactured by DuPont) or the like is used.

In this embodiment, the thickness of BS3 is 10 μm
It is mandatory to: When a BS is formed by pressure transfer, a transfer sheet having a transferable black transfer layer of 10 μm or less must be used. If the thickness of the black transfer layer is too small, it is difficult to prepare the transfer sheet itself, and it is also difficult to provide a sufficient light shielding property.
As a result of the investigation, it has been found that the case where the thickness of BS3 is 10 μm or less is preferable, and the thickness of 5 to 10 μm is particularly preferable.

It is to be noted that the formation of the BS by adhering the black powder toner only to the adhesive portion does not deviate from the gist of the present invention. It is difficult to form a stripe, and the thickness of the BS must be increased in order to provide a sufficient light shielding property.

FIG. 4 shows a screen having a thick BS (a type in which the formed portions are raised by protrusions) and a BS having a thickness of 10 μm.
A description will be made by comparing the optical characteristics with the screen of the present embodiment in the case of m. Both have a lens pitch of 0.24m
m, when the opening width of the lens is 50% of the lens pitch (that is, the line width of the light-shielding pattern is 0.12 mm), and when observing from an oblique direction, when θ becomes FIG. 9 is an explanatory diagram showing whether the observation optical path is blocked by the BS and the opening of the lens cannot be seen (that is, the entire screen looks black). FIG.
In the screen shown in FIG. 4A, θ = 45 °, and FIG.
Is 85 ° in the screen of the present invention, and it is conspicuous that the screen of the present invention can provide a bright image for observation from a wide angle in the left and right directions.

In the case of FIG. 4, although the lens thickness is not considered at all, the above-mentioned aperture ratio is based on the ratio of the lens thickness to the thickness of the light shielding pattern (D '/ D) as a parameter. Can also be considered. The relationship between D '/ D and the aperture ratio is shown in the graph of FIG. From the figure, (D '/ D) is 1
It can be seen that when it is 0% or less, the screen becomes a bright screen having an aperture ratio of 90% or more.

After the formation of the BS3, the diffusion film 4 is laminated on the entire surface including the BS3. Diffusion film 4
For example, YS300 (trade name; manufactured by Somar Kogyo KK) or the like is used, and the side to be laminated on the lenticular sheet can be laminated at room temperature by applying an adhesive treatment.

Finally, a transparent resin film 5 having an antistatic function or an antireflection function is laminated according to the purpose. Examples of the transparent resin film having an antistatic function include a method in which a nonionic, anionic, or cationic surfactant is kneaded into the film, a method in which the surfactant is mixed with a binder and applied to the film surface, A method for forming a conductive film by vacuum-depositing a property imparting substance (for example, indium oxide doped with tin oxide) on the film surface can be used. Examples of the transparent resin film having an antireflection function include SiO ₂ , Al ₂ O ₃ , and CaCO _2.
It can be obtained by coating a film obtained by mixing an inorganic powder such as ₃ with a binder into a paint, and laminating a non-glare film having a roughened surface.

As described above, a lenticular sheet having the structure shown in FIG. 3A is manufactured. Note that FIG. 3 in which the order of forming the BS 3 and the diffusion film 4 is reversed.
It goes without saying that the same applies to the lenticular sheet having the configuration shown in FIG.

[0032]

According to the observation direction (front / diagonal),
Provided is a lenticular sheet for a transmission screen, in which the brightness of the screen does not change, and in particular, the screen does not feel dark when viewed obliquely.

[0033]

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view showing a conventional lenticular sheet.

FIG. 2 is an explanatory diagram showing optical characteristics of a conventional lenticular sheet.

FIG. 3 is an explanatory sectional view showing the lenticular sheets (a) and (b) of the present invention.

FIG. 4 is an explanatory diagram showing optical characteristics (a) and (b) of a lenticular sheet in comparison.

FIG. 5 is an explanatory diagram showing optical characteristics of a lenticular sheet.

FIG. 6 is an explanatory sectional view showing the design of the lenticular sheet of the present invention.

[Description of Signs] 1 ... Transparent support 2 ... Lens part 3 ... Light shielding pattern (BS) 4 ... Diffusion film 5 ... Transparent resin film

Claims (8)

[Claims] 1. A lenticular sheet which constitutes a transmissive screen in combination with a Fresnel lens sheet, comprising a lens portion in which convex cylindrical lenses are juxtaposed at a pitch P, wherein the lens portion is formed from the top of the convex portion of the cylindrical lens. The flat surface of the lenticular sheet having a thickness D up to the opposite flat surface has a width P ′ and a thickness D ′ at positions corresponding to the non-light-collecting portions of the cylindrical lenses.
A lenticular sheet for a transmissive screen, characterized in that the aperture ratio shown below is 90% or more when a stripe-shaped light-shielding pattern is formed on the lenticular sheet. θ = tan ⁻¹ {(PP ′) / 2D} θ ′ = tan ⁻¹ {(PP ′) / 2 (D + D ′)} aperture ratio = (θ−θ ′) / θ 2. The method according to claim 1, wherein the thickness from the top of the convex portion of the cylindrical lens to the flat surface on the opposite side of the lens portion is D, and the thickness of the stripe-shaped light shielding pattern is D '.
2. The lenticular sheet for a transmission screen according to claim 1, wherein D '/ D ≦ 10%. 3. A lens portion in which convex cylindrical lenses are juxtaposed at a pitch of 0.3 mm or less from a cured material of a radiation-curable resin on one surface of a transparent support, and the lens portion is opposite to the support. 2. A stripe-shaped light-shielding pattern is formed at a position corresponding to a non-light-collecting portion of each cylindrical lens on the flat surface on the side.
Or a lenticular sheet for a transmission screen according to claim 2. 4. The lenticular sheet for a transmission screen according to claim 1, wherein the light-shielding pattern has a thickness of 10 μm or less. 5. The lenticular sheet for a transmission screen according to claim 1, wherein the light-shielding pattern is formed via a diffusion layer formed on the flat surface on the side opposite to the lens portion. 6. The lenticular sheet for a transmission screen according to claim 1, wherein a diffusion layer is formed on the light-shielding pattern formed on the flat surface on the side opposite to the lens portion. 7. The lenticular sheet for a transmission screen according to claim 1, wherein a film having an antistatic function is laminated on the outermost surface on the side opposite to the lens portion. 8. The lenticular sheet for a transmission screen according to claim 1, wherein a film having an antireflection function is laminated on the outermost surface on the side opposite to the lens portion.