JPH0782194B2 - Lenticular lens sheet - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a transmissive screen for projecting an image from a picture tube of a projection television receiver, and more specifically, a Fresnel lens. The present invention relates to a lenticular lens sheet which is combined with a sheet to form the transmission screen.

[Conventional technology]

In general, the horizontal of the light emitted from such a transmissive screen,
The following two types are known as factors that define the directional characteristics in the vertical direction. One is the shape of the convex cylindrical lens formed on the lenticular lens sheet, and the other is the type and mixing ratio of the diffusing agent mixed in the lenticular sheet.

However, if the mixing ratio of the diffusing agent is increased by the latter method, the reflection of light is increased by the diffusing agent, which causes a problem that the amount of light emitted from the emission surface is reduced. There is also a problem that individual directional characteristics cannot be controlled.

Therefore, the control of the directional characteristics is performed mainly by the former method using the lens shape and in combination with the latter method using the diffusing agent.

As an example of a lenticular lens sheet adopting such a conventional directional characteristic control method, there is disclosed in JP-A-58-221833.
The examples described in Japanese Patent Publication can be given. In this example, 100% synthetic resin that is the base material of the lenticular lens sheet
The ratio of the light-scattering substance mixed with respect to the weight part and the particle size are specified, and the lens shapes and intervals of the incident surface and the exit surface are also specified.

A cross-sectional view of such a conventional lenticular lens sheet is shown in FIG. 4. As shown in FIG. 4, this shape eliminates the spherical aberration of the convex cylindrical lens 51 on the incident surface, and has a focal length of the convex cylindrical lens. The emission surfaces are arranged at the same position. Reference numeral 52 is a light absorber.

Further, in the conventional example as described in JP-A-58-205140,
The convex cylindrical lens forming the exit surface is arranged such that the center to center of the convex cylindrical lens forming the entrance surface correspond to each other. For this reason, the lights a, b, c, d, e, and f parallel to the optical axis of the incident surface converge to almost one point on the exit surface (as can be seen in FIG. 4).

Therefore, the area of the non-light-collecting portion of the emission surface can be made large, and by applying a coating film as the light absorber 52 to the non-light-collecting portion, it is possible to obtain an image with less contrast deterioration against external light. is doing.

However, in the above-mentioned prior art, no consideration has been given to light rays that are obliquely incident on the convex cylindrical lens that constitutes the incident surface.

[Problems to be solved by the invention]

The problems when the above-described lenticular lens sheet that has been conventionally used is used for a projection television (projection television receiver) will be described below with reference to the drawings.

FIG. 5 is a transverse sectional view generally showing an optical system of a projection television. As shown in the figure, the arrangement of the cathode ray tubes is based on the green cathode ray tube 42, and the blue cathode ray tubes are arranged on the left and right.
41 and a red cathode ray tube 43 are arranged inline laterally. Reference numeral 44 is a projection lens.

Therefore, in order to obtain a normal image without color shift on the screen, special structural consideration is required. This will be described below.

That is, the blue cathode ray tube 41 and the projection lens 44, and the red cathode ray tube 43 and the projection lens 44 do not directly face the Fresnel lens sheet 45, and the angle β ₁ (hereinafter, this angle is referred to as the concentration angle).
These cathode ray tubes 41 and
The light emitted from 43 is incident on the Fresnel lens sheet 45 at an angle of convergence β ₁ .

Further, the light emitted from the Fresnel lens sheet 45 and incident on the incident surface of the lenticular lens sheet 46 is inclined by the converging angle β ₁ as shown in FIG. 6, and the blue projection light and the red projection light are inclined with respect to the green projection light. Will have.

In such a situation, the conventional lenticular lens sheet does not have any special consideration for the light incident from an oblique direction.Therefore, when the image is viewed from the front of the lenticular lens sheet, the image shifts to the right or left. When viewed from a different position, the image becomes a bluish image with blue emphasized or a reddish image with red emphasized, causing a color shift and impairing image quality. .

The mechanism in which such color shift occurs will be specifically described below.

Generally, in a lens surface having a lens cross-sectional shape with a curved portion centered on an intersection with the long axis of an elliptic curve drawn with the reciprocal of the refractive index of the substance forming the lens as the eccentricity, a ray parallel to the optical axis is: It converges to its focal position with no aberration.

By utilizing this property, the cross-sectional shape of the convex cylindrical lens forming the incident surface of the lenticular lens sheet is set to the elliptic curve shape as described above.

FIG. 7 shows a tracing model diagram of incident light rays on such a lens.

In FIG. 7, S is a lens surface formed by the above elliptic curve,
P, P'is the focal point of the ellipse, t is the thickness of the lenticular lens sheet, t'is the height of the lens surface seen from the incident ray position,
h is the height from the optical axis (matching the x-axis) to the incident ray, θ ₃
Is the exit angle of light rays from the lenticular lens sheet, N ₂
Is the refractive index of the material forming the lenticular lens sheet, and N ₁ is the refractive index of air (1.00), the following equation holds and the exit angle θ ₃ is obtained as follows. First, according to the general formula of the ellipse t = a + ae (2) Now, let us say that the eccentricity e = 1 / N ₂ (3).

t ′ = a− {a ² −y ² / (1−e ² )} ^1/2 (4) N ₂ sin θ ₂ = N ₁ sin θ ₃ The above equation (5) is substituted into equation (6). Because y = h now However, N ₂ : Refractive index of screen material N ₁ : Refractive index of air (1.00) h: Incident ray height e: Reciprocal of N ₂ a = t / (1 + e) For any sheet material, pitch of convex cylindrical lens ( When the height of the incident ray passing through the outermost part of the lens surface is h, the pitch is 2h), and when the exit angle θ _{3 of the} ray passing through the outermost part of the lens surface is given, the above (7) By changing the equation, the thickness t of the lenticular lens sheet can be obtained.

As a conventional example, FIG. 6 referred to above is a lateral cross-sectional view showing the shape of a lenticular lens sheet in which the corner lens shapes of the entrance surface and the exit surface are formed according to the same elliptic curve portion. as seen in the light parallel to the optical axis of the convex cylindrical lenses according to the elliptical converged on one point on the exit surface, as shown by the solid line, but it is also possible to control the emission angle of each ray, it focused angle beta ₁ Light that is obliquely incident does not converge to a single point on the exit surface, and the exit angle of the exit light cannot be controlled.

Figure 8 is similar to that shown in FIG. 6, the entrance surface and the exit surface and the lens shape according to the elliptic curve, respectively, centralized angle beta ₁
8.9 degrees, the effective diameter of the entrance lens is 1.2 mm, the effective diameter of the exit lens is 0.6 mm, and the lens surface spacing is 1.5 mm.The conventional lenticular lens sheet is combined with the ordinary Fresnel lens sheet. FIG. 9 is a characteristic diagram showing the directional characteristics of a transmissive screen obtained by optical calculation.

In FIG. 8, when the directivity angle is 0 degree, the red, green, and blue image lights show almost the same relative brightness, but as the directivity angle shifts to the right, the relative brightness of the red image light changes to other images. It will be appreciated that the relative brightness of blue image light tends to be stronger than that of other image lights as it becomes stronger than that of light and the directional angle shifts to the left. In other words, referring to Fig. 5,
Fresnel lens sheet 45 and lenticular lens sheet
As a viewer 48, a transmissive screen composed of 46 is emphasized in blue image light when viewed obliquely from the left, and viewed from the opposite side, red image light is emphasized. In other words, so-called color shift occurs depending on the viewing position, and the image quality is impaired.

The present invention has a problem to be solved to eliminate the occurrence of such color shift in the transmission screen using the conventional lenticular lens sheet. It is therefore an object of the present invention to provide a lenticular lens sheet that enables the above.

[Means for solving problems]

FIG. 9 is a cross-sectional view showing the principle structure of the lenticular lens sheet according to the present invention.

Means for solving the problem will be described with reference to FIG. That is, the above-mentioned object is that in the lenticular lens sheet, the image light incident surface S ₁ side has a convex cylindrical lens shape, and, unlike the prior art, the design degree of freedom (parameter) of the incident surface S ₁ is different. A large number of aspherical shapes are given by the following equation (2).

In addition, the exit surface S ₂
It is also effective to make a non-spherical surface as shown in the following equation (2), like the entrance surface S ₁ .

Furthermore, in the present invention, the exit surface S ₂ side also has a convex cylindrical lens shape, and as the shape of the convex cylindrical lens forming the entrance surface S ₁ side, the center radius of curvature R ₁ is the following (a): Compared with the curvature radius R (= b ² / a) of the curved portion centered on the intersection with the major axis of the elliptic curve shown by the formula, it is within the range shown by the following formula (b), and the lens periphery The concave dimension (lens height) l ₅ ′ from the center of the lens along the lens center axis is within the range shown in the following formula (C), and the convex cylindrical lens forming the exit surface S ₂ side For the shape of, the following (2)
The absolute value of the value obtained by substituting the distance from the central axis of the lenticular lens into the formula obtained by d ² X / dY ² is
The following formula (a) is obtained by deriving the ^second derivative d ² x / dy ² with the lens center axis rather than the absolute value of the value obtained by substituting the distance from the center axis of the lenticular lens. It is small in the shape part near the lens center part along the orthogonal direction, and the distance l ₃ along the direction orthogonal to the lens center axis from the center part is the following (f) except the shape part near the lens center part. to the distance l of the formula, l ₃ <large in the range satisfying the relation of l, l _3> in the range satisfying the relation of l, according its radius of curvature R ₃ is the l ₃ becomes larger, gradually This is achieved by determining the aspherical surface coefficient in the following equation (2) so that the shape becomes smaller.

Note (x ² / a ² ) + (y ² / b ² ) = 1 (b) However, b ² = a ² (1-e ² ) e = 1 / N ₂ N ₂ constitutes a lenticular lens sheet. Refractive index of the material (N ₁ is the refractive index of air 1.00) y is the short axis, x is the long axis and coincides with the lens center axis 1.4R> R ₁ > R… (b) l ₅ > l ₅ ′ > 0.7l ₅ (c) where l ₅ is a lens such that the curve representing the surface shape of the lens is represented by the curved part centered on the intersection with the major axis of the elliptic curve represented by the formula (a). Of the lens periphery in the shape,
The dimension of depression (height of the lens surface) from the center of the lens along the lens axial direction is shown.

However, X is the X axis in the direction coinciding with the center axis of the lens,
It represents the height of the lens surface (function of Y) when the radial direction of the lens is taken as the Y axis, where Y represents the radial distance, RD,
CC, AD, AE, AF.AG ... A is an arbitrary constant, and n is an arbitrary natural number.

l = l ₁ (1-N ₂ ) tan β ₁ (f) where β ₁ is the incident angle and l ₁ is the lens interval.

[Action]

According to the lenticular lens sheet of the present invention, with respect to the green image light incident parallel to the optical axis of the convex cylindrical lens forming the image light incident surface, there is almost no spherical aberration, and the corresponding convex cylindrical lens has The convex cylindrical lens shape of the incident surface and the convex cylindrical lens interval of the incident surface are selected so as to converge on the exit surface. Further, since the shape of the incident surface S ₁ is an aspherical shape represented by the above formula (D), which has many degrees of freedom (parameters) in shape design, it is possible to control the directional characteristics of the screen more precisely than in the prior art. Further, the emission light distribution of the green image light is determined by the shape of the convex cylindrical lens on the emission surface near the optical axis.

On the other hand, the distribution of the outgoing light from the sheet of blue image light and red image light that enters the convex surface of the incident surface and the convex cylindrical lens obliquely depends on the shape of the peripheral portion away from the optical axis of the convex cylindrical lens that constitutes the exit surface. Since each can have an arbitrary distribution, it is possible to realize a screen capable of greatly reducing color shift.

As described above, in the exit surface S ₂ as well, in order to make a large difference between the vicinity of the optical axis and the peripheral portion, the lens shape obtained by the aspherical expression shown in the above equation (d) is required.

〔Example〕

 Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view in the horizontal direction of the screen screen showing the lens shape of a lenticular lens sheet as an embodiment of the present invention. In the figure, the lens pitch P
₀ is 1.2mm, which is equivalent to that of conventional lenticular lenses
And the refractive index of the sheet material is 1.56, and the effective diameter L ₁ of the exit surface is
Design values when the lens diameter L ₂ is 0.56 mm and the lens diameter L ₂ is 0.7 mm are shown below as specific examples.

First, how to read data will be described. A positive sign of the radius of curvature RD indicates that the center of curvature of the lens surface is located in the direction from the entrance surface 23 to the exit surface 22 on the optical axis.

Here, the aspherical surface coefficient is a coefficient when the surface shape is expressed by the following equation.

However, the height of the lens surface (function of Y) when the optical axis direction is X and the lens radial direction is Y axis, RD represents the radius of curvature, and n represents an arbitrary natural number. .

Therefore, if each coefficient of CC, AD, AE, AF, AG ... A is given, the height, that is, the shape of the lens surface is determined according to the above equation (d).

In the table below, as coefficients, CC, AD, AE, AF, AG
Up to the 10th order coefficient,
The present invention is not limited to this, and it is also possible to similarly set coefficients of 12th and higher even orders. Even in such a case, a lens surface that is axially symmetric with respect to the optical axis can be obtained.

t ₁ = 1.5311 mm, L ₁ = 0.56 mm, L ₂ = 0.7 mm, P ₀ = 1.2 mm The incident surface has a small amount of aspherical surface and is close to an elliptical shape. Optimal design is performed using equation (7). Therefore, the image light incident parallel to the optical axis X of the lens converges near the point on the optical axis of the exit surface with almost no influence of spherical aberration.

On the other hand, the image light that is obliquely incident on the incident surface by the concentration angle β ₁ is refracted on the incident surface and then on the exit surface from the optical axis. Converge to a position distant by. Therefore, the aspherical amount of the convex cylindrical lens is increased to The light distribution of the emitted light is optimized by greatly changing the shape in the vicinity.

The directional characteristics of the embodiment described above are shown in FIG. In the figure, the red and blue image lights both have a bimodal characteristic, and the entrance and exit surfaces are elliptical and the eccentricity is the reciprocal of the refractive index of the sheet material. Then, it will be recognized by referring to FIG. 8 that the color shift is improved by 50% at the directional angle of 25 degrees and improved by 64% at the directional angle of 20 degrees.

On the other hand, as can be seen in FIG. 1, the lenticular lens sheet according to this example is superior to the sheet according to the prior art in moldability for the following reasons.

(1) The average curvature of the convex cylindrical lens forming the entrance surface is large, and the amount of depression t ₄ is small.

(2) The amount t ₃ of depression from the projection 25 on the exit surface to the lower end of the lens surface is small.

(3) The average curvature of the convex cylindrical lens that constitutes the exit surface is large, and the amount of depression t ₂ is small.

(4) Between the protrusion 25 formed on the emitting surface and the effective portion L ₁ of the convex cylindrical lens forming the emitting surface, a flat portion (L ₂
The presence of −L ₁ ) / 2 improves the transferability of the lens surface.

Furthermore, by providing a light-shielding layer of the light absorber 24 on the flat portion of the protrusion 25, it is possible to obtain a sheet with little contrast deterioration with respect to external light.

The value of the second derivative of the shape shown in the equation (d) is the value of the second derivative of the lenticular lens surface having an elliptical shape in which the eccentricity, which is the conventional technique, is represented by the reciprocal of the refractive index of the lenticular lens sheet material. A comparison is shown in FIG.

The absolute value of the value obtained by substituting the distance from the lens center axis into the equation obtained by quadratic differentiating the equation showing the lens surface according to the prior art is obtained by quadratic differentiating the equation showing the lens shape according to the present invention. Compared with the absolute value of the value obtained by substituting the distance from the lens center axis into the formula obtained, it is larger near the center axis and is shown in FIG. It will be appreciated that it is growing nearby.

〔The invention's effect〕

 According to the present invention, the following effects can be expected.

(1) The color shift defined by the difference between the red image light and the blue image light can be significantly reduced by the shape of the convex cylindrical lens forming the emission surface.

(2) The amount of depression of the lens surface is small, and improvement in moldability can be expected as compared with the sheet of the related art.

(3) Further, since the convex cylindrical lens forming the entrance surface converges the light on the exit surface with almost no aberration, the area of the non-focusing part of the exit surface becomes large, and a light-shielding layer is provided at this part by a light absorber. By forming it, the contrast deterioration with respect to external light can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention, FIG. 2 is a characteristic diagram showing directional characteristics of an embodiment of the present invention, and FIG. FIG. 4 is a cross-sectional view showing an example of a conventional lenticular lens sheet, and FIG. 5 is a cross-sectional view generally showing an optical system of a projection television. FIG. 7 is a cross-sectional view of another example of a conventional lenticular lens sheet, FIG. 7 is a model diagram of ray tracing in a conventional convex cylindrical lens, and FIG. 8 is a combination of a conventional lenticular lens sheet and a Fresnel lens sheet. FIG. 9 is a characteristic diagram showing the directional characteristic of a conventional transmissive screen, and FIG. 9 is a cross-sectional view showing the principle structure of the lenticular lens sheet according to the present invention. Explanation of symbols 21,46,51,61 ... Lenticular lens sheet, 22 ... Emitting surface, 23 ... Incident surface, 24, 52 ... Light absorber, 25 ... Protrusion, 41 ... Blue cathode ray tube, 42 ... Green cathode ray tube, 43 … Red cathode ray tube, 44
… Projection lens, 45… Fresnel lens sheet, 52… Light absorber, 48… Viewer, N ₁ … Air refractive index, N ₂ … Lenticular lens sheet material refractive index, β ₁ … Incident angle, β ₂ … Refraction angle, β ₃ … Exit angle, R ₁ … Center radius of curvature

Claims (9)

[Claims] 1. A lenticular lens sheet forming a transmissive screen in combination with a Fresnel lens sheet, wherein the image light incident surface S ₁ side has a convex cylindrical lens shape, and the exit surface S ₂ side has the same convex cylindrical lens shape. As the shape of the convex cylindrical lens forming the incident surface S ₁ side, the center radius of curvature R ₁ is a curve centered on the intersection point with the major axis of the elliptic curve represented by the following equation (a). Compared with the radius of curvature R (= b ² / a) of the part, it is within the range shown by the following formula (B) and the size of the depression of the lens peripheral part from the lens center part along the lens center axis ( (Lens height) l ₅ ′ is within the range shown in the following formula (C) and the shape of the convex cylindrical lens forming the exit surface S ₂ side is expressed by the following formula (2) differential
The absolute value of the value obtained by substituting the distance from the central axis of the lenticular lens into the expression obtained by d ² X / dY ² ,
The following formula (a) is obtained by substituting the ^second derivative d ² x / dy ² into the formula obtained by substituting the distance from the central axis of the lenticular lens, and the absolute value of the value It is small in the shape part near the lens center part along the orthogonal direction, and the distance l ₃ along the direction orthogonal to the lens center axis from the center part is the following (f) except the shape part near the lens center part. to the distance l of the formula, l ₃ <large in the range satisfying the relation of l, l _3> in the range satisfying the relation of l, according its radius of curvature R ₃ is the l ₃ becomes larger, gradually A lenticular lens sheet characterized in that an aspherical coefficient in the following formula (2) is determined so that the shape becomes smaller. Note (x ² / a ² ) + (y ² / b ² ) = 1 (b) However, b ² = a ² (1-e ² ) e = 1 / N ₂ N ₂ constitutes a lenticular lens sheet. Refractive index of material y is the minor axis, x is the major axis and is the axis that coincides with the lens center axis 1.4R> R ₁ > R… (b) l ₅ > l ₅ ′> 0.7l ₅ … (c) where l ₅ Is a lens peripheral portion in a lens shape such that a curve representing the surface shape of the lens is represented by a curved portion centered on an intersection point with the long axis of the elliptic curve represented by the formula (a),
The dimension of depression (height of the lens surface) from the center of the lens along the lens axial direction is shown. However, X is the X axis in the direction coinciding with the center axis of the lens,
It represents the height of the lens surface (function of Y) when the radial direction of the lens is taken as the Y axis, where Y represents the radial distance, RD,
CD, AD, AE, AF.AG, ... A is an arbitrary constant and n is an arbitrary natural number. l = l ₁ (1 / N ₂ ) tan β ₁ (f) where β ₁ is the incident angle and l ₁ is the lens interval. 2. A lenticular lens sheet which constitutes a transmissive screen which transmits image light incident from an image generation source and outputs it to the image viewing side, wherein the screen shape on the image light generation side is a screen. A plurality of _first lenticular lenses S ₁ whose longitudinal direction is the screen vertical direction are continuously arranged in the horizontal direction of the screen screen, and the shape of the screen surface on the image viewing side is the vertical direction of the screen screen. A plurality of _second lenticular lenses S ₂ arranged in the longitudinal direction are formed so as to be substantially opposed to the first lenticular lens and continuously arranged in the horizontal direction of the screen screen, and at least the first lenticular lens S 2 is formed. The cross-sectional shape of the screen screen _{1 in} the horizontal direction has a shape that is convex toward the image generation source side, and from the tip of the shape that is convex, When the distance along the optical axis direction of the first lenticular lens is X and the radial distance of the lens from the optical axis is Y, A lenticular lens sheet having an aspherical shape given by the following formula. However, X is the X axis in the direction coinciding with the center axis of the lens,
It represents the height of the lens surface (function of Y) when the radial direction of the lens is taken as the Y axis, where Y represents the radial distance, RD,
CD, AD, AE, AF.AG, ... A is an arbitrary constant and n is an arbitrary natural number. 3. The lenticular lens sheet according to claim 2, wherein the first lenticular lens S ₁ has a fourth or higher order in the formula (d) representing the horizontal screen cross-sectional shape. The lenticular lens sheet, wherein at least one sign of the signs of the higher-order coefficients is different from the sign of the radius of curvature. 4. The lenticular lens sheet according to claim 2 or 3, wherein a light absorption layer having a finite width is provided at each boundary between the _second lenticular lenses S _2. Lenticular lens sheet characterized by being provided. 5. A lenticular lens sheet which constitutes a transmissive screen which transmits image light incident from an image generation source and outputs it to the image viewing side, wherein the screen shape of the image light generation source side is clean. The first lenticular lens whose longitudinal direction is the screen vertical direction
A plurality of S ₁ are arranged continuously in the horizontal direction of the screen screen, and the shape of the screen surface on the image viewing side is the second lenticular lens S ₂ whose longitudinal direction is the vertical direction of the screen screen. A plurality of the first lenticular lenses S ₁ are arranged to face each other in the horizontal direction of the screen screen substantially opposite to the first lenticular lens S ₁ , and at least the second lenticular lens S ₂ has a cross-sectional shape in the horizontal direction of the screen screen. , X is a distance along the optical axis direction of the first lenticular lens S ₁ from the tip of the convex shape which is convex on the image viewing side, and from the optical axis Y is the distance in the lens radial direction
When A lenticular lens sheet having an aspherical shape given by the following formula. However, X is the X axis in the direction coinciding with the center axis of the lens,
It represents the height of the lens surface (function of Y) when the radial direction of the lens is taken as the Y axis, where Y represents the radial distance, RD,
CD, AD, AE, AF.AG, ... A is an arbitrary constant and n is an arbitrary natural number. 6. The lenticular lens sheet according to claim 5, wherein the second lenticular lens S ₂ has a fourth or higher order in the formula (d) representing the horizontal screen cross-sectional shape of the second lenticular lens S _2. The lenticular lens sheet, wherein at least one sign of the signs of the higher-order coefficients is different from the sign of the radius of curvature. 7. The lenticular lens sheet according to claim 5 or 6, wherein a light absorption layer having a finite width is provided at each boundary between the _second lenticular lenses S _2. Lenticular lens sheet characterized by being provided. 8. A lenticular lens sheet which constitutes a transmissive screen which transmits image light incident from an image generation source and outputs it to the image viewing side, wherein the screen shape on the image light generation side is a screen. A plurality of _first lenticular lenses S ₁ whose longitudinal direction is the screen vertical direction are continuously arranged in the horizontal direction of the screen screen, and the shape of the screen surface on the image viewing side is long in the vertical direction of the screen screen. A plurality of _second lenticular lenses S ₂ oriented in a horizontal direction are formed substantially continuously facing the _first lenticular lens S ₁ and arranged continuously in the horizontal direction of the screen screen. The screen cross-section in the horizontal direction of the screen of ₁ is convex on the image source side. And the shape of the first lenticular lens S _{1 in} the vicinity of the optical axis is a shape that can be approximated by the equation of the elliptic curve obtained by the following equation (a), and the radius of curvature RD ( = B ² / a) and conic constant CC
^{(= B 2 / a 2 -1} ) below derived from a (i) formula coefficients a, b
With respect to the lens interval t obtained by substituting in the following equation (2), the surface distance t ₁ between the first lenticular lens S ₁ and the second lenticular lens S ₂ satisfies the relation of t> t _1. Lenticular lens sheet characterized by being. (X ² / a ² ) + (y ² / b ² ) = 1 (b) where b ² = a ² (1-e ² ) e = 1 / N ₂ N ₂ is the material that makes up the lenticular lens sheet Refractive index y is a minor axis, x is a major axis and is an axis that coincides with the lens center axis t = a + ae (2) 9. A lenticular lens sheet constituting a transmissive screen that transmits image light incident from the image generation source side and emits it to the image viewing side, wherein the screen shape of the image light generation source side is: A plurality of _first lenticular lenses S ₁ whose longitudinal direction is the screen screen vertical direction are continuously arranged in the screen screen horizontal direction, and the shape of the image viewing side screen surface is the screen screen vertical direction. A plurality of _second lenticular lenses S ₂ each having a lengthwise direction are formed so as to be substantially opposed to the _first lenticular lenses S ₁ and continuously arranged in the horizontal direction of the screen screen, and at least the first lenticular lenses S ₂ are arranged. sectional shape of the screen the screen horizontal direction of the lenticular lens S ₁ or the second lenticular lens S ₂ screen display horizontal cross section One of the shapes is a shape given as a function of the distance from the optical axis of the lenticular lens, and has a shape that is symmetrical with respect to the optical axis, and a function obtained by quadratic differentiating the function, When the distance from the optical axis is substituted for the vicinity of the optical axis and the peripheral portion, the rate of change of the value obtained thereby with respect to the distance from the optical axis differs between the vicinity of the optical axis and the peripheral portion. Lenticular lens sheet to be used.