JPH11271884A - Rear projection type screen equipped with prism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the peak gain of a screen and also to improve an ambient brightness ratio in the case an observer views a screen, without damaging the light using efficiency, as to a rear projection type screen. SOLUTION: As for the rear projection type screen 10 used in a projection optical system and for making projection light incident on the screen at right angle from behind the screen, the screen 10 is constituted of a fresnel lens sheet with a prism 11, a lenticular lens sheet 12 for dispersing the light projected from the sheet 11 in a horizontal direction. The fresnel lens sheet with a prism 11 is provided with a linear prism 13 on the projection light source 1 side, and also, the lens 11 is provided with a circular fresnel lens 14 on the observer P side, the linear prism 13 functions as a linear fresnel lens for condensing the video light in the screen height direction, and the circular fresnel lens 14 works for condensing the video light toward the center of the screen.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear projection type screen used for a rear projection type display.

[0002]

2. Description of the Related Art As shown in FIG. 15, a rear projection type display has a projection tube 1 for projecting an optical image, a projection lens 2 for enlarging an optical image projected from the projection tube 1, and an enlarged optical system. A rear projection type screen 3 for forming an image is formed. An observer P operates a projection tube 1 behind the screen 3.
To observe the optical image magnified and projected on the screen 3.

Here, as the rear projection type screen 3, a Fresnel lens sheet 4 for collecting a light beam projected from the projection tube 1 in the direction of the observer P, and a light emitted from the Fresnel lens sheet 4 in a horizontal direction of the screen ( A lenticular lens sheet 5 that is dispersed at a proper ratio at a predetermined angle in a screen width direction (screen width direction) and a screen height direction (screen height direction) to widen a viewing angle in a predetermined range. Many screens are used.

In recent years, in a rear projection type display, it has been required to shorten the distance between the projection lens 2 and the screen 3 in order to make the display thinner. In order to satisfy this requirement, it is necessary to increase the Fresnel angle of the Fresnel lens sheet 4. However, when the Fresnel angle is increased, the reflection loss at the outer peripheral portion of the Fresnel lens sheet 4 increases, and the ratio of the brightness of the corner of the screen 3 to the center of the screen 3 (so-called peripheral luminance ratio) decreases. The problem occurs.

Further, when the peak gain of the screen 3 is increased in order to increase the brightness of the rear projection display, it is necessary to adjust the dispersibility of the light emitted from the screen 3 in the constituent material of the screen 3. As the amount of diffusing material incorporated is reduced, the lowering of peripheral brightness becomes more and more problematic.

Conventionally, various countermeasures have been proposed for the problem of such a decrease in peripheral luminance. For example, FIG.
As shown in FIG. 2, a unit lens is formed by disposing minute cylindrical lenses 7u on the surface of the Fresnel lens sheet 4 opposite to the surface on the Fresnel lens 8 side so that the longitudinal direction thereof is horizontal. There is a method of forming a lenticular lens 7 for vertical diffusion provided in a large number in the direction (for example, JP-A-2-18540). The vertical diffusion of light of such a vertical diffusion lenticular lens is shown in FIG.
As shown in FIG. 7, there is also known a method of increasing the brightness at the peripheral portion as compared with the central portion of the screen, thereby suppressing a decrease in luminance at the peripheral portion (JP-A-7-134338).

Further, as shown in FIG. 18, a method of improving the brightness of the peripheral portion of the screen by combining two linear Fresnel and lenticular lenses 9a and 9b to direct the light in the vertical direction toward the observer. Yes (USP45
No. 31812).

There is also a method in which two linear Fresnel lenses for vertical and horizontal are combined to deflect image light in the vertical direction (US Pat. No. 5,477,380).

As a Fresnel lens sheet, there is also a method in which a Fresnel lens is provided on an incident surface of light from a projection tube and a linear prism for deflecting light in a vertical direction is provided on an exit surface (US Pat. No. 4,512,631).

[0010]

However, in the method using the vertical diffusion lenticular lens 7 shown in FIG. 16 described above, when the screen peak gain is low, the vertical light diffusion of the vertical diffusion lenticular lens 7 is prevented. The color unevenness (color shift) of the screen is not a problem due to the contribution of the property, but when the screen peak gain is a brightness exceeding about 7, the refractive index of the material is different due to the difference in color (difference in wavelength), so Fresnel There is a problem that the reflection loss at the lens differs depending on the color difference, which causes the color unevenness of the screen to deteriorate. Also, a lenticular lens 7 for vertical diffusion is used to increase the peripheral brightness.
When the diffusivity of the screen is increased, there is also a problem that the screen gain at the center of the screen decreases.

When a vertical lenticular lens is used in which the vertical diffusion of light is larger at the periphery than at the center of the screen, a vertical lenticular lens having a uniform vertical diffusion of light is used. 17, it is possible to achieve both the brightness of the peripheral portion of the screen and the brightness of the entire screen. However, in this case as well, in the peripheral portion of the screen, as shown in FIG. There is a problem that the light utilization efficiency cannot be improved because the light Lo diffuses into the ineffective area above and below the screen.

In the method using two linear Fresnel and lenticular lenses 9a and 9b in combination in FIG. 18, the linear Fresnel and lenticular lenses 9a and 9b are used.
However, there is a problem that the loss due to light reflection is large as compared with the case where a circular Fresnel lens is used. Further, in the screen using the linear Fresnel and lenticular lenses 9a and 9b, there is also a problem that light utilization efficiency in an effective area of the screen is reduced due to light diffusivity.

Even a screen that combines two vertical and horizontal linear Fresnel lenses and deflects image light in the vertical direction has a problem that light loss is large as compared with the case where a circular Fresnel lens is used.

In a screen using a Fresnel lens sheet having a Fresnel lens on the incident surface of light from the projection tube and a linear prism on the exit surface for deflecting light in the vertical direction, the light from the projection tube is used. There is a problem that the loss of light increases by providing the Fresnel lens on the incident surface of the light emitting device.

An object of the present invention is to solve the above-mentioned problems of the prior art by increasing the peak gain of the screen and improving the peripheral luminance ratio without impairing the light use efficiency. Aim.

[0016]

Means for Solving the Problems The present inventors have found that the peripheral luminance ratio of the screen is such that the vertical diffusion characteristic of the light is dominant, so that the light is applied vertically to the light incident side of the Fresnel lens sheet. By arranging a linear prism to control and condensing the light emitted from the corners of the Fresnel lens sheet in the direction of the observer, it was found that the peripheral brightness of the screen could be improved without impairing the light use efficiency. The invention has been completed.

That is, the present invention relates to a rear projection type screen used in a projection optical system in which projection light is vertically incident on a screen, wherein the screen comprises a Fresnel lens sheet with a prism and a lenticular lens sheet; The attached Fresnel lens sheet has a linear prism on the surface on the projection light source side, has a circular Fresnel lens on the surface on the observer side, and the linear prism is a linear Fresnel lens that condenses image light in the screen height direction. Acting, the circular Fresnel lens acts to condense the image light in the center direction of the screen, and the lenticular lens sheet acts to disperse the light emitted from the Fresnel lens sheet with the prism in the horizontal direction. A rear projection screen with a prism is provided.

In particular, regarding the shape of the linear prism of the rear projection screen, the sectional shape of the unit prism constituting the linear prism is such that the cross-sectional shape in the screen height direction of the screen is
It consists of a straight part and a curved part, and the unit prism pitch is p
(Mm), the radius when the shape of the curved part is approximated by a circle is r
(Mm), and when the height of the prism is h (mm), an embodiment is provided in which 0.1 ≦ r / p ≦ 4 (where p ≧ 0.05) and h ≧ 0.005.

[0019] Further, the prism angle of the linear prism is 0 ° at the center of the screen and 3 ° to 15 ° at a position outside 90% from the center of the screen in the screen height direction. provide.

In the rear projection screen described above, the lenticular lens sheet is a double-sided lenticular lens sheet having lenticular lenses on the incident side and the exit side of the image light, and the top of the lenticular lens on the exit side faces the incident side. An aspect is provided in which the lenticular lens is formed at a substantially condensing position.

According to the rear projection type screen of the present invention,
A linear prism acting as a linear Fresnel lens is formed on the light incident surface of the Fresnel lens sheet.
Whereas the lenticular lens for vertical diffusion used in conventional rear projection screens attempts to improve the peripheral brightness of the screen by using the light dispersion, this linear prism observes the light emitted from the screen Can be deflected in the direction of the user, so that the peripheral brightness in the height direction of the screen can be efficiently improved.

Further, if a circular Fresnel lens is formed on the light incident surface of the Fresnel lens sheet, the light incident on the rise surface of the circular Fresnel lens does not pass through the screen, so that the light use efficiency is reduced.
According to the present invention, since the circular Fresnel lens is formed on the light emission side surface of the Fresnel lens sheet,
Loss of incident light can be reduced.

Further, regarding the shape of the linear prism of the rear projection type screen, it is preferable that the cross-sectional shape of the unit prism constituting the linear prism is made up of a straight portion and a curved portion in the screen height direction of the screen (that is, the curved portion). If the prism has a rounded apex angle), the light incident on the prism from this curved portion is diffused, so that the ghost that occurs when the prism angle is a specific angle can be eliminated. Therefore, even when the screen is observed from a deep angle, the screen is observed brightly.

If the prism angle of the linear prism is 0 ° at the center of the screen and 3 ° to 15 ° outside the center of the screen in the height direction of the screen and 90% from the center of the screen, the angle of incidence on the incident side is determined. Light loss in the linear prism and the circular Fresnel lens on the emission side can be reduced, and the light transmittance of a sheet made of a combination of the linear prism and the circular Fresnel lens can be increased.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. In each of the drawings, the same reference numerals represent the same or equivalent components.

FIG. 1 is an external view of a rear projection screen 10 with a prism according to the present invention, and FIG.
FIG. 2 is an external view of a Fresnel lens sheet with a prism 11 used in FIG.

This screen 10, like the conventional rear projection screen shown in FIG. 15, is used in a projection optical system in which light projected from a projection tube enters the screen 10 perpendicularly from the back of the screen 10. It is.

As shown in FIG. 1, this screen 10
Is composed of a Fresnel lens sheet 11 with a prism and a lenticular lens sheet 12. As shown in FIG. 2, the Fresnel lens sheet 11 with a prism has a unit prism having a constant height in the screen horizontal direction x and a variable height in the screen height direction y on the projection light source side. 1
3u has a plurality of linear prisms 13 arranged in the screen height direction y. Further, a circular Fresnel lens 14 is provided on the observer side.

When the linear prism 13 is formed on the incident surface of the Fresnel lens sheet 11 as described above, the prism angles of the unit prisms 13u are made different in the vertical direction y of the screen of the Fresnel lens sheet 11 and the direction of the prism is changed. As shown in FIG. 2, the upper and lower portions in the screen height direction y can be formed symmetrically. Therefore, the light emitted from the Fresnel lens sheet 11 can be largely deflected as it goes to the upper and lower corners of the Fresnel lens sheet 11, and as shown in FIG. The light can be directed toward the observer P without impairing the light use efficiency.

The light-condensing action of the linear prism 13 is similar to the light-condensing action of the linear Fresnel lens for condensing the image light in the screen height direction y. Since the light is condensed and its refraction angle is large, the present invention uses the linear prism 13 in combination with the circular Fresnel lens 14, so that
The refraction angle can be reduced and the reflection loss is small.

The circular Fresnel lens 14 on the exit surface of the Fresnel lens sheet 11 condenses the light emitted from the projection tube 1 at a predetermined condensing position. On the other hand, the linear prism 13 on the incident surface of the Fresnel lens sheet 11 largely deflects the light emitted from the Fresnel lens sheet 11 as it goes to the upper and lower corners of the Fresnel lens sheet 11 as described above. Accordingly, as shown in FIG. 4, in the peripheral portion of the screen 10, the condensing distance D _v of the screen height direction y of the screen 10 is shorter than the condensing distance D _h of the screen horizontal direction x. In this case, in order to uniform the brightness of the screen 10, in the region of the outer center portion 10 ₀ from the screen 10% or more in height direction y of the screen 10, the screen condensing distance D _v of the height direction y screen condensing distance D _h in the horizontal direction x
It is preferable to make the length shorter.

Further, the focal length f of the circular Fresnel lens 14 which defines a condensing distance D _h of the screen horizontal direction x of the screen 10 (mm), the screen 10 from the viewpoint of improving the overall luminance, Fresnel from the projection light source Assuming that the distance to the lens sheet 11 is D _a (mm), it is preferable to set the distance to satisfy 0.8 <f / D _a <1.0.

FIG. 5A is a sectional view of a preferred shape of the unit prism 13 u of the linear prism 13. In the present invention, the sectional shape of the unit prism 13u is shown in FIG.
Although a triangle may be used as shown in FIG.
As shown in (a), the shape is preferably represented by a straight line part forming the prism surface 13a and a curved part 13b approximated by an arc. By forming the unit prism 13u in such a shape, light incident on the linear prism 13 from the curved portion 13b is diffused.
A ghost generated at a specific prism angle θ when the unit prism 13u has the sectional shape of FIG. 5B can be eliminated. Even when the observer observes the screen 10 from a deep angle, the screen 10 is observed brightly.

The sectional shape of the unit prism 13u may be such that the rise surface 13c of the prism has a concave lens shape as shown in FIG. 5 (c). This can also eliminate ghosts.

The shape of the unit prism 13u is, as shown in FIG.
c may have fine irregularities. This can also eliminate ghosts.

Further, regarding the sectional shape of the unit prism 13u, the radius r (m
m) 1 pitch length p (mm), prism height h
(Mm), from the viewpoint of maintaining the uniformity of the brightness of the entire screen when the screen 10 is observed from a position other than the position of the observer P shown in FIG. 3, 0.1 ≦ r / p ≦ 4 (However, p ≧ 0.05) and h ≧ 0.005 are preferable.

Also, the prism angle θ of the linear prism 13
(Deg) is 0 ° at the center of the screen, and 90% from the center of the screen in the screen height direction of the screen.
It is preferable that the angle is 3 ° to 15 ° at the outermost position.
As a result, as shown in FIG. 6, when the focusing distance of the Fresnel lens sheet with a prism 11 is constant, the light transmittance T (%) at the corner of the screen of the Fresnel lens sheet with a prism 11 is increased. And the loss of light can be reduced.

The prism angle θ (deg) in FIG.
And the light transmittance T (%) can be obtained by calculating the reflectance of the surface of the circular Fresnel lens 14 and the surface of the linear prism 13. The example shown in FIG. 6 is calculated in the case where the circular Fresnel lens 14 and the linear prism 13 are combined so that the focusing distance of the screen is constant.

As a mode of making the prism angle θ or the height h of the unit prism 13u different between the center of the screen and the upper and lower ends of the screen, for example, as shown in FIG. 7 or FIG. It is preferable to continuously change the distance Y from the screen center to the screen height direction. Further, as shown by a broken line in the drawing, a flat area where no unit prism is formed may be provided at the center of the screen.

The shape of the linear prism 13 having the above shape can be derived by the following (Equation 1).

[0041]

(Equation 1)

The prism angle θ (deg) can be obtained by the following (Equation 2).

[0043]

Θ = arcTAN (dH / dY) (Equation 2)

In the above (Equation 1) and (Equation 2), C,
K, D, E, F, and G are the shape factors of the change in prism height, Y is the distance from the center of the screen 10, and H is the prism depth.

On the other hand, the lenticular lens sheet 1 constituting the rear projection type screen 10 with a prism of the present invention.
As shown in FIG. 1, as shown in FIG. 1, an incident side lenticular lens 12 i is provided on the incident side of the image light, an output side lenticular lens 12 o is provided on the output side, and the top of the output side lenticular lens 12 o is an incident side lenticular. It is preferable to use a double-sided lenticular lens sheet formed at a substantially condensing position of the lens 12i. Further, it is preferable that the light absorbing layer 15 is formed on the non-light-collecting portion of the incident-side lenticular lens 12i of the emission-side lenticular lens 12o.

[0046]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments.

Examples 1 to 3, Comparative Examples 1 and 2 The screen shown in FIG. 1 (Examples 1 to 3), the screen shown in FIG. 15 (Comparative Example 1), or the lenticular lens and lenticular lens sheet for vertical diffusion shown in FIG. Using a screen (Comparative Example 2) consisting of an observer side), a 50-inch size rear projection display was manufactured.

Table 1 shows the shape factor when the shape of the Fresnel lens sheet of these screens is represented by the above (Equation 1). As the lenticular lens sheet constituting these screens, a double-sided lenticular lens sheet with a black stripe having a pitch of 0.72 mm was used.

The condensing distance (m) on the left and right (horizontal direction) of the screen, the condensing distance (m) on the up and down (height direction), the screen peak gain, the peripheral luminance ratio (%), and the CYE color coordinates of the screen corner The magnitude of the amount of shift from the color coordinates at the center of was determined. In this case, the distance between the projection tube and the screen is
In Examples 1 and 3 and Comparative Examples 1 and 2, it was 826 mm, and in Example 2, it was 866 mm. The measurement position of the above-mentioned evaluation item was a position 3 m in front of the screen. In order to adjust the screen peak gain to be constant, in the Fresnel lens sheet with prism and Comparative Example 1, a diffusing material was appropriately dispersed in the sheet.

Table 1 shows the results.

[0051]

[Table 1]

From the results in Table 1, it can be seen that in the screens of Examples 1 to 3 in which the linear prism is formed on the incident side surface of the Fresnel lens sheet of the screen, the peripheral luminance ratio (%) and the center of the CYE color coordinate at the corner of the screen. It can be seen that the magnitude of the shift amount from the color coordinates of the part is improved as compared with the screen of Comparative Example 1. Also, it can be seen that the screens of Examples 1 to 3 are superior in the peripheral luminance ratio to the screen of Comparative Example 2 having the lenticular lens for vertical diffusion on the incident side of the Fresnel lens sheet. Therefore, according to the present invention, it is understood that a screen having a high peripheral luminance ratio can be obtained.

Reference Example 1 Distance D _a (mm) from the projection light source to the Fresnel lens sheet
And to investigate the optimum relationship between the focal length f (mm) of the circular Fresnel lens, set the distance D _a to the Fresnel lens sheet to various values of 500~1200mm from the projection light source, whereas, (f / D _a ) was set to various values of 0.75 to 1.05, was calculated distance D _a and the (f / D _a) the distance between the focal point and the Fresnel lens sheet determined from the D _b (mm).

The results are shown in Table 2 and FIG.

Thus, when the value of (f / D _a ) is smaller than 1.0, it can be seen that the image light is converged in the direction of the observation point and the screen becomes bright. If the light is condensed too much when it is smaller than 0.8, there is a high risk of yellowing and cyan coloring at the periphery of the screen.

Therefore, the value of (f / D _a ) is
It turns out that 0.8-1.0 is preferable.

[0057]

[Table 2]

REFERENCE EXAMPLE 2 Regarding the sectional shape of the unit prism 13u of the linear prism (see FIG. 5A), the radius of an arc approximating the curved portion 13b is r (mm), and the length of one pitch is p (mm). )), To obtain the optimum value of r / p, the shape coefficients C and K of (Equation 1) representing the shape of the linear prism and the unit prism 1
Projection distance a of 3u prism surface 13a in the screen height direction
(mm) and the projection distance b (mm) of the curved portion 13b of the unit prism 13u in the screen height direction, using the unit prism 13
As u, the following four shapes were assumed, and for each, r / p in a region where the distance Y from the center of the screen to the screen height direction was up to 500 mm was determined. In addition,
These four shapes are shown in FIGS. In the drawing, the “r-free shape” means a case where the radius r of the curved part is 0, and the approximate shape means a case where the prism shape is approximated using the projection distances a and b.

(1) When the prism angle θ is small and the radius r of the curved part is large: C = 1.0E-4, K = −0.44, a = 0.7, b = 0.64 (2) The prism angle θ is small and the curve When the radius r of the portion is small: C = 1.0E-4, K = -0.44, a = 0.7, b = 0.30 (3) When the prism angle θ is large and the radius r of the curved portion is large: C = 5.0E- 4, K = −0.44, a = 0.7, b = 0.64 (4) When the prism angle θ is large and the radius r of the curved portion is small: C = 5.0E−4, K = −0.44, a = 0.7, b = 0.30

The results are shown in Table 3 and FIG. Thereby, the shape of the unit prism of the embodiment is such that r / p is 0.1
~ 4 was confirmed to be satisfied. When r / p is smaller than this range, the ghost light becomes strong, and
If p is larger than this range, light cannot be effectively collected. Therefore, it can be seen that the appropriate range of r / p is this range.

[0061]

[Table 3]

[0062]

According to the present invention, the peak gain of the screen is increased, and the efficiency of light utilization is not impaired.
The peripheral luminance ratio can be improved.

[Brief description of the drawings]

FIG. 1 is an external view of a rear projection screen with a prism according to the present invention.

FIG. 2 is an external view of a Fresnel lens sheet with a prism.

FIG. 3 is an explanatory view of light rays of a Fresnel lens sheet with a prism.

FIG. 4 is an explanatory view of light rays of a rear projection type screen with a prism.

FIG. 5 is a sectional view of a unit prism.

FIG. 6 is a relationship diagram between a prism angle and a light transmittance of a Fresnel lens sheet with a prism.

FIG. 7 is a diagram illustrating a relationship between a prism angle of a unit prism and a distance from a screen center to a screen height direction.

FIG. 8 is a diagram illustrating a relationship between a lens height of a unit prism and a distance from a screen center to a screen height direction.

[9] The ratio of the distance D _a between the focal length f of the circular Fresnel lens from the projection light source to the Fresnel lens sheet (f / D _a), the distance D _a from the projection light source to the Fresnel lens sheet, the focal point and it illustrates the relationship between the distance D _b between the Fresnel lens sheet.

FIG. 10 is a diagram showing the relationship between the distance Y from the center of the screen in the screen height direction and r / p.

FIG. 11 is a shape diagram of a representative cross section of a unit prism.

FIG. 12 is a shape diagram of a representative cross section of a unit prism.

FIG. 13 is a shape diagram of a representative cross section of a unit prism.

FIG. 14 is a shape diagram of a representative cross section of a unit prism.

FIG. 15 is an explanatory view of general rays of light of a rear projection display.

FIG. 16 is a cross-sectional view of a conventional Fresnel lens sheet.

FIG. 17 is a sectional view of a conventional Fresnel lens sheet.

FIG. 18 is a perspective view of a conventional Fresnel lens sheet.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Projection tube 2 Projection lens 3 Rear projection type screen 4 Fresnel lens sheet 5 Lenticular lens sheet 10 Rear projection type screen with prism 100 ₀ Center part of screen 11 Fresnel lens sheet with prism 12 Lenticular lens sheet 12i Incident side lenticular lens 12o Exit side Lenticular lens 13 Linear prism 13a Unit prism surface 13b Curved portion of unit prism 13c Rise surface of unit prism 13u Linear prism unit prism 14 Circular Fresnel lens 15 Light absorbing layer a Projection distance of prism surface of unit prism in screen height direction condensing distance D _h horizontal direction from the projection distance D _a projection light source to the screen height direction of the curved portion of the b unit prism until Fresnel lens sheet distance D _v screen height direction of the condenser Separation h Height of unit prism Lo Light diffused to invalid area P Observer p Length of one pitch of unit prism r Radius of curved part of unit prism T Light transmittance x Horizontal direction (width direction of screen) y Vertical direction (Screen height direction) Y Distance from screen center to screen height direction

Continued on front page (72) Inventor Hideki Kobayashi Kuraray Co., Ltd. 2-28 Kurashiki-cho, Nakajo-cho, Kitakanbara-gun, Niigata

Claims (6)

[Claims] 1. A rear projection type screen used in a projection optical system in which projection light is vertically incident on a screen, wherein the screen comprises: a prismatic Fresnel lens sheet;
A lenticular lens sheet, wherein the Fresnel lens sheet with a prism has a linear prism on a surface on a projection light source side and a circular Fresnel lens on a surface on an observer side, and the linear prism converts image light to a screen height. Acts as a linear Fresnel lens that focuses light in the direction, the circular Fresnel lens acts to focus image light in the direction of the center of the screen, and the lenticular lens sheet horizontally shifts light emitted from the Fresnel lens sheet with a prism. A rear projection screen with a prism, which has a function of dispersing in a direction. 2. The prism according to claim 1, wherein the condensing distance in the screen height direction of the screen is shorter than the condensing distance in the screen horizontal direction in a region outside the screen center by at least 10% of the screen height. With rear projection screen. Wherein the focal length of the circular Fresnel lens f, and the distance from the projection light source to the Fresnel lens sheet was set to _{D a, 0.8 <f / D} a <1.0 is a second aspect of the prism With rear projection screen. 4. A sectional shape of a unit prism constituting a linear prism includes a straight portion and a curved portion in a screen height direction of a screen, and a pitch of the unit prism is p (m).
m), and the radius when the shape of the curved portion is approximated by a circle is r (m
2. The rear projection with a prism according to claim 1, wherein, when m) and the height of the prism is h (mm), 0.1 ≦ r / p ≦ 4 (where p ≧ 0.05) and h ≧ 0.005. Type screen. 5. The prism angle of the linear prism is 0 ° at the center of the screen, and 3 ° to 15 ° at a position outside 90% from the center of the screen in the screen height direction. 2. A rear projection screen with a prism according to 1. 6. The lenticular lens sheet is a double-sided lenticular lens sheet having a lenticular lens on an incident side and an exit side of image light, and a top of the lenticular lens on the exit side is located substantially at a condensing position of the lenticular lens on the incident side. The rear projection type screen with a prism according to claim 1, which is formed.