JP2004287119A - Transmission type screen and projection image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission type screen having a small difference of brightness in respective parts of the horizontal direction of a screen with respect to the transmission type screen using a total reflection lenticular lens, and to provide a projection image display device using the transmission type screen. <P>SOLUTION: The transmission type screen comprises at least a Fresnel lens sheet on the light source side and the total reflection lenticular lens sheet on the observer side. The lenticular lens sheet has a plurality of ridge-shaped unit deflection parts which makes a vertical direction of screen surface to the longitudinal direction in succession in the horizontal direction of the screen surface, on the surface of the observer side. The inclined surface in the unit deflection parts is allowed to be a total reflection surface that totally reflects the image light made incident from the light source side. Further, the Fresnel lens sheet has a focal distance (f) satisfying the following relation with respect to the set projection distance (f1) from the light source to the screen: the relation is f≥f1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

表１に示すように、光源から当該スクリーンまでの投射距離（ｆ１）に対し、当該フレネルレンズシートの焦点距離（ｆ）が、ｆ≧ｆ１を満たす条件とした実施例においては、ｆ＜ｆ１となる比較例１と比較して、スクリーン各位置に輝度差が少なく、良好な結果が得られた。
【００６３】
【発明の効果】
以上述べたように、本発明によれば、レンチキュラーレンズとして全反射レンチキュラーレンズを用いた透過型スクリーンにおいて、光源から当該スクリーンまでの投射距離（ｆ１）に対し、当該フレネルレンズシートの焦点距離（ｆ）が、ｆ≧ｆ１を満たすものとすることによって、スクリーンの横方向における輝度差を少ないものとすることができる。
【００６４】
さらに本発明においては、フレネルレンズシートの光源側の面に、スクリーン面の垂直方向の光量を補正する拡散要素を設ける、特に、前記拡散要素による光の拡散量が、スクリーンセンター高さ位置における量よりも、垂直方向の両端部における量の方が大きいものであるものとして設けることにより、上記したようなスクリーンの横方向における輝度差の低減を、スクリーンの縦方向における光量変化をもたらすことなく得ることができるものである。
【図面の簡単な説明】
【図１】全反射レンチキュラーレンズの単位偏向部における入射光の偏向の様子を模式的に示す図である。
【図２】（ａ）は、フレネルレンズが集光系として機能する場合における、スクリーンの横方向（水平方向）各部の光量分布を模式的に示すものであり、（ｂ）は、（ａ）に示すように、観察者がスクリーンの横方向からスクリーンを見た際のスクリーン各部の輝度の状態を模式的に示す図面である。
【図３】（ａ）は、フレネルレンズが発散系として機能する場合における、スクリーンの横方向（水平方向）各部の光量分布を模式的に示すものであり、また（ｂ）は、（ａ）に示すように、観察者がスクリーンの横方向からスクリーンを見た際のスクリーン各部の輝度の状態を模式的に示す図面である。
【図４】（ａ）は、フレネルレンズが発散系として機能する場合における、観察者がスクリーンセンター高さからスクリーンを見た際のスクリーンの縦方向（垂直方向）各部における輝度の状態を模式的に示す図面、（ｂ）は、フレネルレンズが発散系として機能する場合において、スクリーン面の垂直方向の光量を補正する拡散要素を設けた一例における、観察者がスクリーンセンター高さからスクリーンを見た際のスクリーンの縦方向（垂直方向）各部における輝度の状態を模式的に示す図面、また（ｃ）は、フレネルレンズが発散系として機能する場合において、スクリーン面の垂直方向の光量を補正するより好ましい拡散要素を設けた別の例における、観察者がスクリーンセンター高さからスクリーンを見た際のスクリーンの縦方向（垂直方向）各部における輝度の状態を模式的に示す図面である。
【図５】（ａ）本発明に係る透過型スクリーンの一実施態様の構成を模式的に示す図であり、（ｂ）〜（ｄ）は、それぞれ（ａ）に示すフレネルレンズシートのＤ，Ｅ，Ｆ部における形状を模式的に示す拡大図である。
【図６】本発明に係る透過型スクリーンに用いられる全反射レンチキュラーレンズシートの別例を模式的に示す図である。
【符号の説明】
１…単位偏向部
２ａ、２ｂ…傾斜面
３…出光面
４…光透過層
５…光吸収層
６…前面板
７…凹凸部
１０…透過型スクリーン
２０…フレネルレンズシート
２３…フレネル凸レンズ
２４…拡散要素（単位凸レンズ部）
３０…レンチキュラーレンズシート[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a transmissive screen used in a projection image display device such as a single light source projection television (PTV) such as a liquid crystal projector or a digital light processor (DLP).
[0002]
[Prior art]
A single light source projector for matrix display such as LCD and DLP is superior to a conventional CRT projector in terms of brightness, compactness, and the like, and has been commercialized in recent years.
[0003]
Conventionally, a transmissive screen used in such a single light source projector is generally configured to have at least a Fresnel lens on the light source side and a lenticular lens on the observer side.
[0004]
The Fresnel lens converges the projection light divergently incident from the center of the screen toward the periphery, and refracts the image light beam into substantially parallel light. Then, the lenticular lens is arranged on the front surface of the emission surface of the Fresnel lens, and the projection light converted into the substantially parallel light is diffused so that it can be recognized as an image from various angles.
[0005]
In the case of a transmissive screen for a CRT projector, a double-sided lenticular lens sheet is used as a lenticular lens in order to correct a color shift caused by a position difference between the three tubes projected by three tubes of RGB. In contrast, in the case of a transmission type screen for a single light source projector, since image light is projected through a single-lens lens and no color shift occurs due to a position difference, as a lenticular sheet, a single-sided lenticular having a lens portion on only one side is used. Lens sheets can be used.
[0006]
In other words, this lenticular sheet has a configuration in which a lens portion formed by continuously arranging a plurality of vertically long cylindrical lenses having a longitudinal direction in the vertical direction of the screen surface in the horizontal direction of the screen surface is formed on only one surface, and the image light is formed. It has the effect of refracting and diffusing in the horizontal direction.
[0007]
By the way, since such a single light source projector performs a matrix display using pixels, moire generated between the lens pitch of a lenticular lens of a transmissive screen for displaying an image and the pixel pitch of a projected image. ) Can be a problem.
[0008]
In order to avoid such moiré, the ratio of the pitch of the lenticular lens to the horizontal pitch of the pixel image projected on the screen is 1 / (N + 1/2) (N is an integer of 1 or more. ) Is known (see Patent Document 1). Here, N is usually a value of 2 or more. For example, if the pitch of the pixel images projected on the screen is 1.0 mm, the pitch of the lenticular lens satisfying the above equation is 0.4 mm if N is 2, 0.28 mm if N is 3, If N is 4, the value is as small as 0.222 mm. In recent years, since the screen has been refined and the pitch of the pixel images has been reduced, the pitch of the lenticular lens to be set is also set to a fine pitch of, for example, about 0.2 mm or less in order to avoid moire. There is a need.
[0009]
It is known that in a transmission screen, a light absorbing layer called a black stripe, a black matrix, or the like is effective as a means for reducing the adverse influence of external light. In the case where a black stripe is provided as a light absorbing layer on a lenticular lens sheet in which each lens has a semicircular or semi-elliptical cross section, each line of the black stripe is formed in a non-light-collecting portion through which refracted light does not pass. There is a need to.
[0010]
When the pitch of the conventional lenticular lens sheet is reduced as described above, the unit lens is reduced in size, so that the focusing distance is shortened. Therefore, the distance from the unit lens to the non-light-condensing portion also needs to be shortened, and the thickness of the lenticular lens sheet needs to be reduced. However, as described above, when the lenticular lens sheet becomes thinner due to miniaturization, a problem arises in that high-precision molding becomes difficult in general extrusion molding with high production efficiency, and the lenticular lens and the light absorbing layer It is necessary to perform high-accuracy alignment, which causes an increase in manufacturing equipment cost and a reduction in productivity.
[0011]
Therefore, as a lenticular lens that does not require alignment, the cross-sectional shape of the unit lens is not a substantially semicircular or semi-elliptical shape that condenses light, but rather a part that transmits incident light, a part that totally reflects light, and a part that totally reflects light. Patent Literature 2 proposes a lenticular lens having a concavo-convex shape in which a light absorbing layer is formed (hereinafter, referred to as a “total reflection lenticular lens”).
[Patent Document 1]
JP-A-2-97791
[Patent Document 2]
Japanese Patent Publication No. 2-22932
[0012]
[Problems to be solved by the invention]
However, in a transmissive screen using such a total reflection lenticular lens as a lenticular lens, when an observer views the screen from the lateral (horizontal) direction of the screen, the luminance difference in the lateral direction of the screen is large, and there is room for improvement. was there.
[0013]
Accordingly, an object of the present invention is to provide a transmission screen using a total reflection lenticular lens, which has a small difference in luminance at each part of the screen, and a projection image display device using the same.
[0014]
[Means for Solving the Problems]
The present invention for solving the above-mentioned problems is a transmission screen including at least a Fresnel lens sheet on the light source side and a lenticular lens sheet on the observer side, wherein the lenticular lens sheet has a surface on the observer side. A plurality of ridge-shaped unit deflecting units having a longitudinal direction perpendicular to the screen surface in a continuous manner in the horizontal direction of the screen surface, and the inclined surface of the unit deflecting unit totally reflecting image light incident from a light source side. The Fresnel lens sheet has a focal length (f) satisfying the following relationship with respect to a set projection distance (f1) from the light source to the screen. It is a transmission type screen that is a feature.
[0015]
f ≧ f1
Further, in the transmission screen of the present invention, it is preferable that the Fresnel lens sheet has a diffusion element for correcting the amount of light in a direction perpendicular to the screen surface on the light source side surface.
[0016]
Further, in the transmission screen of the present invention, it is preferable that the amount of light diffusion by the diffusing element is larger at both ends in the vertical direction than at the screen center height position.
[0017]
Further, in the transmission screen according to the present invention, it is more preferable that the direction of light diffusion by the diffusing element at both ends in the vertical direction of the Fresnel lens sheet is more toward the screen center.
[0018]
The present invention for solving the above-mentioned problems is further directed to a projection image display device having a light source, and a transmissive screen having a Fresnel lens sheet on the light source side and a lenticular lens sheet on the viewer side. The lens sheet has a plurality of ridge-shaped unit deflecting parts having a longitudinal direction perpendicular to the screen surface in a continuous direction in the horizontal direction of the screen surface on a surface on the observer side, and an inclined surface in the unit deflecting unit as a light source. The Fresnel lens sheet has a total reflection surface that totally reflects image light incident from the side, and the Fresnel lens sheet has a focal length (f1) with respect to a projection distance (f1) from the light source to the screen. f) is arranged at a position satisfying the following relationship:
[0019]
f ≧ f1
Further, in the projection image display device according to the present invention, it is preferable that the Fresnel lens sheet has a diffusion element for correcting a light amount in a direction perpendicular to a screen surface on a surface on a light source side.
[0020]
Further, in the projection image display device of the present invention, it is preferable that the amount of light diffusion by the diffusing element is larger at both ends in the vertical direction than at the screen center height position.
[0021]
Further, in the projection image display device of the present invention, it is more preferable that the direction of light diffusion by the diffusing element at both ends in the vertical direction of the Fresnel lens sheet is directed more toward the screen center.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
The present inventors have found that, in a transmission screen using such a total reflection lenticular lens as a lenticular lens, when an observer views the screen from the horizontal (horizontal) direction of the screen, a luminance difference occurs in the horizontal direction of the screen. As a result of diligent research and investigation into the cause, we found that this phenomenon was caused by the distance from the light source to the screen (f1) and the focal length of the Fresnel lens (f), and changed this point. As a result, the present inventors have concluded that this problem can be improved, and have reached the present invention. Hereinafter, this point will be described in detail.
[0023]
FIG. 1 is a view schematically showing how incident light is deflected in a unit deflection unit of a total reflection lenticular lens.
[0024]
Light incident on the total reflection lenticular lens at a certain angle is totally reflected by the left and right inclined surfaces (total reflection surfaces) 2a and 2b in the unit deflecting unit 1 and transmitted from the light exit surface 3 as shown in FIG. Is divided into light that does not hit the inclined surface and passes through the light emitting surface 3 as it is. Except for light that passes through the light emitting surface 3 as it is, a larger amount of light is emitted in the direction opposite to the incident angle to the unit deflection unit. Is done.
[0025]
Conventionally, even in a transmission type screen using a total reflection lenticular lens as a lenticular lens, a Fresnel lens is collected as in the case where each lens of the optical system uses a lenticular lens sheet having a semicircular or semielliptical cross section. In order to form an optical system, the focal length (f) of the Fresnel lens sheet is designed to be smaller than the projection distance (f1) from the light source to the screen, that is, f <f1.
[0026]
FIG. 2A shows a case where the focal length (f) of the Fresnel lens is smaller than the projection distance (f1) (f <f1), and the Fresnel lens functions as a light collecting system. FIG. 2B schematically shows a light amount distribution in each portion in a horizontal direction (horizontal direction) of the screen. FIG. 2B shows a view of the screen from a horizontal direction of the screen as shown in FIG. 5 is a drawing schematically showing the state of the brightness of each part of the screen when it is turned on.
[0027]
In this case, since the image light from the light source side is condensed by the Fresnel lens, light having an incident angle inclined toward the center of the screen near the both ends in the horizontal direction of the screen is generated by the total reflection surface of the lenticular lens. The light is totally reflected, becomes outgoing light having an angle inclined to the screen outer side O opposite to the incident angle, and a large amount of light is emitted. For this reason, as shown in the figure, the light amount distribution in each portion of the screen in the horizontal direction (horizontal direction) has a higher peak near the side edges (points A and C) of the screen. For this reason, when the observer looks at the screen from one side end (point A) of the screen, as shown in FIG. 2B, the side end (point A) close to itself is considerably bright, On the other hand, there is a disadvantage that the opposite side end (point C) which is far from itself appears quite dark, and the luminance difference between point A and point C becomes extremely large.
[0028]
On the other hand, in the present invention, as described above, the position of the Fresnel lens relative to the light source is such that the Fresnel lens is located at a projection distance (f1) from the light source to the screen so that the Fresnel lens becomes a divergent system. The focal length (f) of the sheet is set to be large or equal, that is, f ≧ f1.
[0029]
FIG. 3A shows a case where the focal length (f) of the Fresnel lens is longer than or equal to the projection distance (f1) (f ≧ f1) as in the present invention, and the Fresnel lens functions as a diverging system. 3A and 3B schematically show the light amount distribution in each part of the screen in the horizontal direction (horizontal direction). In FIG. 3B, as shown in FIG. 5 is a drawing schematically showing the state of the brightness of each part of the screen when viewing FIG.
[0030]
In this case, the image light from the light source side is converged to some extent by the Fresnel lens, but remains as a divergent system. Therefore, near both lateral ends of the screen, an incident angle inclined toward the outer side O of the screen. Is totally reflected by the total reflection surface of the lenticular lens, and is emitted light having an angle inclined toward the screen inner side I opposite to the incident angle, and a large amount of light is emitted. For this reason, as shown in the figure, the light amount distribution in each portion of the screen in the horizontal direction (horizontal direction) has a peak near the side edge (points A and C) of the screen more than in the case of f <f1 described above. It will be located on the center side. Therefore, when the observer views the screen from one side end (point A) of the screen, as shown in FIG. 3B, the side end (point A) close to the user and the opposite end far from the user. The luminance difference between the side end (point C) of the side is relatively small, and the uniformity of brightness is improved.
[0031]
However, since f ≧ f1 is set so that the Fresnel lens is a divergent system as described above, the divergent system is also provided in the vertical direction (vertical direction) of the screen, and therefore, the brightness uniformity in the vertical direction of the screen is maintained. Will decrease. That is, when the upper end in the vertical direction of the screen is D, the center is E, and the lower end is F, when viewed from the center height of the screen, as shown in FIG. , F and the central portion E have a large luminance difference.
[0032]
In order to improve such a problem of luminance in the vertical direction of the screen, in a preferred embodiment of the present invention, as described above, the Fresnel lens sheet has a light amount in the vertical direction of the screen surface on its light source side surface. It is assumed that a diffusion element to be corrected is provided. In particular, the amount of light diffusion by the diffusion element is larger at both ends in the vertical direction than at the screen center height position. By providing such a diffusion element, when observing the screen from the front in the center of the screen, the amount of light at the upper and lower ends of the screen increases, and as shown in FIG. The difference in luminance between the portion E and the portion E is smaller than that in the case of FIG. 4A, and the uniformity of brightness in the vertical direction is improved.
[0033]
Furthermore, in a more preferred embodiment of the present invention, the direction of light diffusion by the diffusing element at both ends in the vertical direction of the Fresnel lens sheet is directed more toward the screen center. As described above, when the diffusion direction of the light by the diffusion element is set to be more toward the screen center side, the light amount at the upper and lower ends of the screen is further increased in the observation from the front of the screen center, as shown in FIG. Thus, the difference in brightness between the upper and lower ends D and F of the screen and the center E is smaller than that in the case of FIG. 4B, and the uniformity of brightness in the vertical direction is further improved. It is.
[0034]
Next, the present invention will be described in detail based on preferred embodiments.
[0035]
FIGS. 5A to 5D are diagrams schematically showing the configuration of one embodiment of the transmission screen according to the present invention. As shown in FIG. 5A, the transmission screen 10 according to the present invention has at least a Fresnel lens sheet 20 on the light source side and a total reflection lenticular lens sheet 30 on the observer side.
[0036]
Thus, in the present invention, the Fresnel lens sheet has a relationship in which the focal length (f) of the Fresnel lens sheet satisfies f ≧ f1, with respect to the projection distance (f1) from the light source to the screen, more preferably. , F are 1.0 to 1.4 times f1, more preferably 1.0 to 1.25 times f1.
[0037]
As described above, when f <f1, the difference in brightness between the screen portions when the observer views the screen from the lateral direction of the screen becomes large, making the screen difficult to see.
[0038]
In the present invention, the Fresnel lens sheet may be, for example, a multifocal system having two or more focal points. In such an embodiment using a multifocal Fresnel lens sheet, any focal length of the Fresnel lens sheet satisfies the above-described expected condition with respect to the projection distance (f1) from the light source to the screen. It is necessary to arrange the Fresnel lens sheet at such a position.
[0039]
In general, the projection distance (f1) from the light source to the screen in a projection image display device having such a transmission screen is predetermined from the viewpoint of design such as the outer shape of the device. There are many cases. Therefore, in order to satisfy the above relationship in the present invention, it is necessary to improve the Fresnel lens sheet side. In this case, as compared with the Fresnel lens sheet satisfying f <f1, the lens sheet satisfying f ≧ f1 Since the lens angle of the Fresnel lens is reduced, it is expected that the brightness and the uniformity can be improved by reducing the reflection loss on the light exit surface.
[0040]
The configuration of the Fresnel lens sheet 20 used in the transmission screen according to the present invention is not particularly limited as long as the Fresnel convex lens 23 is formed on at least one of the observer side surface 21 and the light source side surface 22. Instead, any structure may be used. Typically, for example, the surface 22 on the light source side has a planar shape, and the shape of the surface 21 on the observer side has a Fresnel convex lens shape.
[0041]
However, in the present invention, it is preferable that the Fresnel lens sheet has, on its light source side surface 22, a diffusion element for correcting the amount of light in the vertical direction of the screen surface. It is desirable to arrange a diffusion element such that the amount of diffusion at both ends D and F in the vertical direction is larger than the amount at the screen center height position E.
[0042]
The diffusing element disposed on the light source side surface 22 of the Fresnel lens sheet is not particularly limited, and may be, for example, a mode formed by uneven portions physically formed on the sheet surface, or a resin or the like forming the sheet. An embodiment in which light diffusing particles and the like are mixed in the matrix can be adopted.
[0043]
In the example shown in FIG. 5, a plurality of ridge-shaped unit convex lens portions 24 whose longitudinal direction is the horizontal direction of the screen surface are continuously provided in the vertical direction of the screen surface as such diffusing elements on the surface 22 on the light source side. Have Then, as shown in FIGS. 5B to 5D, the positions at both ends D and F in the vertical direction are larger than the amounts at the screen center height position E. The optical axes of the unit convex lenses at D and F are formed so as to be shifted from the optical axes of the unit convex lenses at the screen center height position E.
[0044]
Although not particularly limited, the diffusion angle of light in the screen vertical direction by a diffusion element disposed on the light source side surface 22, for example, the unit convex lens in FIG. 5, is, for example, in a range of about 1 to 5 °. In particular, it is desirable to set the light diffusion angles at both end positions D and F to be larger than the light diffusion angles at the screen center height position E by about 1 to 3 °. .
[0045]
In the present invention, more preferably, with respect to the diffusion element disposed on the light source side surface 22 of the Fresnel lens sheet, the direction of light diffusion by the diffusion element at both ends D and F in the vertical direction is largely toward the screen center. It is assumed. The specific configuration for causing the diffusion direction to be directed to the screen center side in this way is not particularly limited. For example, as described above, for example, as shown in FIGS. This is performed by shifting the optical axis of the unit convex lens at the partial positions D and F toward the screen center, or making the curvature of the unit convex lens at both end positions D and F larger than the lens curvature at the center position E. Can be done.
[0046]
The lens shape and the like of the Fresnel convex lens 23 of the Fresnel lens sheet 20 are not particularly limited, and depend on the size of the screen and the like, but the lens pitch is, for example, about 0.05 to 0.2 mm. The focal length can be, for example, about 600 to 900 mm.
[0047]
Further, the material forming the Fresnel lens sheet 20 is not particularly limited, and may be any known material conventionally used as an optical material. For example, (meth) acrylic resin, polystyrene resin And highly translucent resins such as (meth) acrylate-styrene copolymer resin, polycarbonate resin and vinyl chloride resin. Particularly, a (meth) acrylic resin is preferable because of its high light transmittance. In addition to the thermoplastic resin composition, various resin compositions such as thermosetting, ultraviolet curable, and electron beam curable can be used in order to facilitate lens processing. In addition, transparent glass, ceramics, and the like may be used.
[0048]
The lenticular lens sheet 30 used in the transmission screen according to the present invention is formed of a light-transmitting material such as a light-transmitting resin. Are provided in parallel with the horizontal direction H of the screen surface. As shown in FIG. 5, for example, the ridge-shaped unit deflection section 1 has a substantially trapezoidal cross section, and its inclined surfaces 2a, 2b are totally reflected to totally reflect image light incident from the light source side. The surface on the top side of the ridge, which is substantially perpendicular to the thickness direction of the lens sheet, is the light emitting surface 3.
[0049]
FIG. 6 is a view schematically showing another preferred example of such a total reflection lenticular lens sheet.
[0050]
In this example, the lenticular lens sheet has a light transmitting layer 4 and a light absorbing layer 5. That is, the light transmitting layer 4 in the lenticular lens sheet shown in FIG. 6 corresponds to the real part of the lenticular lens sheet shown in FIG. The light absorbing layer 5 is a so-called black stripe or the like, and fills the V-shaped groove between the ridge-shaped unit deflection parts 1 in the example shown in FIG. The formed line has a longitudinal direction that is the vertical direction V of the screen surface, and a plurality of lines are arranged in parallel with the horizontal direction H. Therefore, the light absorbing layer 5 exists only above the inclined surfaces 2a and 2b (as viewed from the light source side) of the unit deflecting unit 1 provided on the surface of the light transmitting layer 4 on the observer side. 1 does not exist above the light exit surface 3.
[0051]
The light absorbing layer 5 generally has a lower refractive index than the light transmitting material of the light transmitting layer 4 so that the inclined surfaces 2a and 2b function as a total reflection surface with respect to the incident light from the light source. However, if a low-refractive-index layer (not shown) is separately provided at the interface with the inclined surfaces 2a and 2b, the material constituting the light-absorbing layer 5 has no such restriction on the refractive index. The light absorbing layer 5 functions to absorb light (external light) incident from the observer side and reduce the amount of light reflected to the observer side. As will be described later, it is composed of a resin matrix in which various coloring agents such as pigments and dyes are blended.
[0052]
In the total reflection lenticular lens sheet 30 shown in FIG. 6, a front plate 6 is adhered on the surface of the light transmitting layer 4 and the light absorbing layer 5 on the observer side (light emitting portion side). Further, on the surface on the light source side, uneven portions 7 having a fine pitch are provided.
[0053]
The front plate 6 can function as a diffusion layer by mixing a diffusing agent, for example, and the unidirectional light emitted from each unit deflection unit 1 is diffused by the diffusing agent in the front plate 6. Since the light travels in a plurality of directions, it is possible to reduce unevenness in the brightness of the image due to the position of the observer. In addition, the front plate 6 can function as an ultraviolet absorbing layer by blending an ultraviolet absorbing agent, for example, and can prevent deterioration of a plastic material constituting an internal optical system. Further, a hard coat layer, an anti-reflection layer, and the like for providing scratch resistance can be formed on the light emitting side surface of the front plate 6.
[0054]
The fine pitch irregularities 7 provided on the side of the light source of the lenticular lens sheet 30 improve the contrast of an image by scattering external light that enters the lenticular lens sheet 30 from the observer side. Since the pitch of the concavo-convex portions 7 is considerably smaller than the pitch of the unit deflecting portions 1, there is no particular need for alignment between the unit deflecting portions 1 and the concavo-convex portions 7. .
[0055]
However, as described above, the lenticular lens sheet 30 used in the present invention may be a so-called total reflection type, in which the unit deflection unit has a total reflection surface that totally reflects the image light incident from the light source. For example, the above-described examples are not particularly limited, and any types may be used.
[0056]
For example, as for the shape of the unit deflecting unit, the light emitting surface 3 is flat, convex, concave, or the like, and the inclined surfaces 2a, 2b face each other with the same inclination angle, or Various modes such as those having different inclination angles from each other, and those in which one inclined surface changes its angle on the way so that incident light is deflected a plurality of times on the inclined surface of the unit deflector. Can be taken. In addition, for example, as in the above-described example, not only the deflecting portion (lens portion) provided on the surface on the observer side but also the deflecting portion (lens portion) provided on the surface on the light source side. Can also be used. Further, the pitch of the unit deflecting unit can be, for example, about 0.05 to 0.2 mm, although it is not particularly limited because it depends on the size of the screen and the like. , 2b may be about 5 to 12 °, and each light exit surface 3 may have a width of 45 to 80% of each unit deflection unit.
[0057]
Further, the material for forming the light transmitting layer of the lenticular lens sheet 30 is not particularly limited, and may be any known material conventionally used as an optical material. Resins having high light-transmitting properties, such as resins, polystyrene resins, (meth) acrylate-styrene copolymer resins, polycarbonate resins, and vinyl chloride resins can be used. Particularly, a (meth) acrylic resin is preferable because of its high light transmittance. In addition to the thermoplastic resin composition, various resin compositions such as thermosetting, ultraviolet curable, and electron beam curable can be used in order to facilitate lens processing. In addition, transparent glass, ceramics, and the like may be used.
[0058]
In the case where the light absorbing layer 5 is formed on the lenticular lens sheet 30, the material serving as the matrix of the absorbing layer is a material having a lower refractive index than the light transmitting material forming the light transmitting layer 4. However, the present invention is not particularly limited, and the same resins as those exemplified as those forming the light transmitting layer 4 and low refractive index acrylate resins into which silicon or fluorine is introduced can be used. Further, the light absorbing agent blended in the resin matrix of the light absorbing layer 4 is not particularly limited, and any known light absorbing agent can be used. For example, carbon black, titanium black, etc. Black or other various pigments such as red, blue and yellow color pigments, extender pigments, various dyes such as azo dyes and phthalocyanine dyes, or acrylic crosslinked particles colored with these pigments and / or dyes Can be used alone or in combination.
[0059]
Further, the projection image display device according to the present invention is a projection image display device having a light source and the transmission screen according to the present invention as described above, and by using the transmission screen as described above, The luminance difference in the horizontal direction is small, and the visibility is improved.
[0060]
The projection image display device according to the present invention includes various types such as a projection type television receiver, and the light source is not limited to a single light source. For example, a three tube type light source (RGB type) or the like may be used. A plurality of light sources may be used.
[0061]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples.
Examples 1 and 2 and Comparative Example 1
A projection image display device was manufactured using the following conditions and materials, and the difference in luminance from the horizontal direction of the screen due to the difference in the focal length of the used Fresnel lens was examined. Table 1 shows the obtained results.
Conditions and materials:
・ Distance from LCD projector (Epson, ELP-53) to screen (f1)
f1 = 650 mm
・ Lenticular lens sheet
The total reflection surface of the unit deflecting unit 1 has an inclination angle of 6 °, the light emitting surface 3 of the unit deflecting unit 1 has a width of 40% (60 μm) of the unit deflecting unit, and the pitch between the unit deflecting units. (150 μm). The unit deflecting part of this lenticular lens sheet is formed by transferring from a mold with a urethane acrylate-based UV-curable resin, and a light diffusing agent is added to the light emitting surface side (observer side) of the unit deflecting part. (The vertical direction half-value angle was 9 °).
・ Fresnel lens sheet
Three types of Fresnel lenses having a focal length (f: 570 mm (Comparative Example 1), 650 mm (Example 1), and 790 mm (Example 2)) were used. In addition, this Fresnel lens sheet is formed by transferring a Fresnel convex lens having such a focal length from a mold on a viewer-side surface of an acrylic resin sheet using a urethane acrylate-based UV-curable resin, The surface on the light source side was a flat surface of an acrylic resin sheet.
・ Screen size and measurement point
The screen size (horizontal direction) was 1100 mm, and the measurement was made at three places, that is, both right and left ends (A, C) and a screen center (B).
・ Measurement distance and position
The screen was observed at an angle of 45 ° to the left from the screen center and from a position 2 m away from the screen. The measurement height was the same as the height of the screen center.
· measuring device
The luminance was measured in a dark room environment using a luminance meter (LS-110, manufactured by Minolta) as a luminance measuring device.
[0062]
[Table 1]

As shown in Table 1, with respect to the projection distance (f1) from the light source to the screen, in the embodiment where the focal length (f) of the Fresnel lens sheet satisfies f ≧ f1, f <f1. Compared with Comparative Example 1, the difference in luminance at each position on the screen was small, and good results were obtained.
[0063]
【The invention's effect】
As described above, according to the present invention, in a transmission type screen using a total reflection lenticular lens as a lenticular lens, the focal length (f1) of the Fresnel lens sheet with respect to the projection distance (f1) from the light source to the screen. ) Satisfies f ≧ f1, so that the luminance difference in the horizontal direction of the screen can be reduced.
[0064]
Further, in the present invention, a diffusion element for correcting the amount of light in the vertical direction of the screen surface is provided on the light source side surface of the Fresnel lens sheet. In particular, the amount of light diffusion by the diffusion element is an amount at a screen center height position. By providing a larger amount at both ends in the vertical direction than in the above, it is possible to reduce the luminance difference in the horizontal direction of the screen as described above without causing a change in the light amount in the vertical direction of the screen. Is what you can do.
[Brief description of the drawings]
FIG. 1 is a view schematically showing how incident light is deflected in a unit deflection unit of a total reflection lenticular lens.
FIG. 2 (a) schematically shows a light amount distribution in each portion of a screen in a horizontal direction (horizontal direction) when a Fresnel lens functions as a light condensing system, and FIG. 3 is a drawing schematically showing a state of luminance of each part of the screen when an observer looks at the screen from a lateral direction of the screen.
FIG. 3 (a) schematically shows a light amount distribution of each part in a horizontal direction (horizontal direction) of a screen when a Fresnel lens functions as a diverging system, and FIG. 3 is a drawing schematically showing a state of luminance of each part of the screen when an observer looks at the screen from a lateral direction of the screen.
FIG. 4A is a schematic diagram illustrating a state of luminance in each part of the screen in a vertical direction (vertical direction) when a viewer views the screen from the screen center height when the Fresnel lens functions as a diverging system. (B) shows an example in which, when the Fresnel lens functions as a divergent system, an observer viewed the screen from the screen center height in an example in which a diffusion element for correcting the amount of light in the vertical direction of the screen surface was provided. FIG. 3C is a diagram schematically showing the state of luminance in each part of the screen in the vertical direction (vertical direction) at the time, and FIG. 3C illustrates a case where the Fresnel lens functions as a divergent system and corrects the amount of light in the vertical direction on the screen surface. In another example with a preferred diffusing element, the vertical direction of the screen when the viewer views the screen from the screen center height The state of the luminance in the vertical direction) each part is a drawing schematically showing.
5A is a view schematically showing a configuration of an embodiment of a transmission screen according to the present invention, and FIGS. 5B to 5D respectively show D and D of the Fresnel lens sheet shown in FIG. It is an enlarged view which shows the shape in E and F part typically.
FIG. 6 is a view schematically showing another example of the total reflection lenticular lens sheet used for the transmission screen according to the present invention.
[Explanation of symbols]
1. Unit deflection unit
2a, 2b ... inclined surface
3. Light emitting surface
4: Light transmission layer
5 ... Light absorbing layer
6 ... Front plate
7. Uneven part
10 ... Transmissive screen
20 ... Fresnel lens sheet
23 ... Fresnel convex lens
24 ... Diffusion element (unit convex lens part)
30 Lenticular lens sheet

Claims (8)

A Fresnel lens sheet on the light source side, and a transmissive screen having at least a lenticular lens sheet on the observer side, wherein the lenticular lens sheet has a longitudinal direction on a surface on the observer side, a direction perpendicular to the screen surface. A plurality of ridge-shaped unit deflecting portions are continuously provided in the horizontal direction of the screen surface, and the inclined surface in the unit deflecting portion is a total reflection surface that totally reflects image light incident from the light source side, Further, the Fresnel lens sheet has a focal length (f) satisfying the following relationship with a set projection distance (f1) from the light source to the screen.
f ≧ f1 The transmission type screen according to claim 1, wherein the Fresnel lens sheet has a diffusion element for correcting a light amount in a direction perpendicular to a screen surface on a surface on a light source side thereof. The transmissive screen according to claim 2, wherein the amount of light diffusion by the diffusing element is greater at both ends in the vertical direction than at the screen center height position. 4. The transmission screen according to claim 2, wherein the direction of light diffusion by the diffusion element at both ends in the vertical direction of the Fresnel lens sheet is directed toward the screen center side. 5. A light source, a projection image display device having a transmissive screen in which a Fresnel lens sheet on the light source side and a lenticular lens sheet on the observer side are at least arranged, wherein the lenticular lens sheet has a viewer-side surface, It has a plurality of ridge-shaped unit deflecting parts continuously extending in the horizontal direction of the screen surface with the longitudinal direction being the vertical direction of the screen surface, and the inclined surface in the unit deflecting unit totally reflects the image light incident from the light source side. The Fresnel lens sheet is disposed at a position where the focal length (f) of the Fresnel lens sheet satisfies the following relationship with respect to the projection distance (f1) from the light source to the screen. A projection video display device characterized in that:
f ≧ f1 The projection image display device according to claim 5, wherein the Fresnel lens sheet has a diffusion element for correcting a light amount in a direction perpendicular to a screen surface on a surface on a light source side. 7. The projection image display device according to claim 6, wherein the amount of light diffusion by the diffusing element is larger at both ends in the vertical direction than at the screen center height position. 8. The projection image display device according to claim 6, wherein the direction of light diffusion by the diffusion element at both ends in the vertical direction of the Fresnel lens sheet is directed toward a screen center side. 9.

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