JP2007171561A - Screen and rear projection display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission screen capable of projecting a clear image by a simple configuration and a rear projection display apparatus provided with the screen. <P>SOLUTION: Since a horizontal compound lens surface 2 is a compound lens surface obtained by superposing a horizontal linear Fresnel lens surface and a horizontal lenticular lens surface and a vertical compound lens surface 4 is a compound lens surface obtained by superposing a vertical linear Fresnel lens surface and a vertical lenticular lens surface, the screen 13 achieves a refractive action based on a circular Fresnel lens, a horizontal lenticular lens and a vertical lenticular lens only by two lens surfaces, i.e. the horizontal compound lens surface 2 and the vertical compound lens surface 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a transmissive screen and a rear projection display device including the screen.

The transmissive screen projects an image of projection light incident from the back onto a display surface in front of the screen. Such a transmission screen is often used in a rear projection display device (hereinafter also referred to as a “rear projector”) including a screen and a projection device that projects projection light within one individual.
In such a screen, the projection light incident on the screen while being magnified is condensed to form a parallel light beam substantially perpendicular to the screen surface, and the projection light is distributed horizontally on the display surface. And a horizontal lenticular lens that forms an image and improves the viewing angle dependency. Further, a screen having a total of three lens surfaces by adding a vertical lenticular lens that distributes projection light in the vertical direction has been known.
In addition, a circular Fresnel lens having a concentric shape is frequently used as the Fresnel lens, but it has problems such as difficulty in manufacturing and high cost.

FIG. 11 is a perspective sectional view of a main part of a conventional screen. In order to solve these problems, for example, a screen 200 of Patent Document 1 has been proposed.
As shown in FIG. 11, in the screen 200, the function of the circular Fresnel lens is distributed on two lens surfaces, a horizontal linear Fresnel lens 212 and a vertical linear Fresnel lens 214, which are easy to manufacture.
Further, a horizontal lenticular lens 216 and a micro lenticular lens 218 having a function of a vertical lenticular lens are provided and have a total of four lens surfaces.

FIG. 12 is a cross-sectional view of a main part of a conventional screen having a different mode.
Patent Document 2 proposes a screen 250 formed by superimposing a circular Fresnel lens and a horizontal lenticular lens.
In the screen 250, a primer layer 253 is provided on a base material sheet 252, and a horizontal lenticular lens layer 254 and a circular Fresnel lens layer 255 are laminated thereon. The horizontal lenticular lens layer 254 and the circular Fresnel lens layer 255 are made of transparent synthetic resins having different refractive indexes.

JP-A-6-350945 JP-A-5-88265

However, since the screen 200 of Patent Document 1 has four lens surfaces, the configuration becomes complicated. In addition, the amount of projection light is attenuated. In addition, there is a problem that it is difficult to obtain a clear image due to the difference in aberration caused by the manufacturing variation of each of the four lens surfaces and the assembling accuracy when incorporated in the screen.
In addition, in the screen 250 of Patent Document 2, the horizontal lenticular lens layer 254 and the circular Fresnel lens layer 255 are made of transparent synthetic resins having different refractive indexes. However, in the existing transparent resin, the refractive index is large. Different resins were not found, and it was difficult to increase the refractive index. For this reason, it is difficult to obtain the desired optical performance with a single laminated lens, and there is a problem that it is difficult to obtain a clear image. In addition, it is difficult to manufacture two lenses as a single laminated lens as much as or more than a conventional circular Fresnel lens.
As described above, the conventional screen has a problem that the configuration is complicated, that the production is difficult, and that it is difficult to obtain a vivid image.

  In order to solve the above-described problems, an object of the present invention is to provide a transmissive screen capable of projecting a clear image with a simple configuration and a rear projection display device including the screen.

  In order to achieve the above object, a screen of the present invention is a transmissive screen including a back surface on which projection light from a projection device is incident and a display surface on which an image by the projection light is projected. A horizontal linear Fresnel lens surface that condenses the horizontal component of the projection light into a parallel light beam that is substantially perpendicular to the display surface, and a parallel light beam that condenses the vertical component of the projection light and is substantially perpendicular to the display surface A lenticular lens surface that distributes projection light to at least one of the two lens surfaces including a vertical linear Fresnel lens surface and any one of the lens surfaces. Are superimposed to form a compound lens surface.

In the present specification, “superimposition of lens surfaces” means that when there are a first lens surface and a second lens surface, each having a predetermined refractive action, the first lens surface and the second lens surface. A compound refraction effect obtained by continuously transmitting through a surface is achieved by a single compound lens surface.
According to this configuration, the lenticular lens surface that distributes the projection light is further superimposed on at least one of the provided lens surfaces to form a compound lens surface. One lens surface provides the refractive action of two lens surfaces.
Thus, unlike the conventional screen configuration, which is composed of three to four lens surfaces, a horizontal linear Fresnel lens surface, a vertical linear Fresnel lens surface, a horizontal lenticular lens surface, and preferably a vertical lenticular lens surface, The screen of the present invention can achieve the same function by two compound lens surfaces.
Furthermore, since the screen can be configured with a small number of compound lens surfaces, the effects of manufacturing variations due to the large number of lens surfaces and the effects of assembly accuracy can be reduced, so that the desired optical performance with less aberration can be obtained. .
Therefore, according to the present invention, it is possible to provide a transmissive screen capable of projecting a clear image with a simple configuration.

  According to the screen of the present invention, the horizontal linear Fresnel lens surface or the lenticular lens surface superimposed on the vertical linear Fresnel lens surface is a horizontal lenticular lens surface that distributes the projection light in the horizontal direction or the projection light. It is preferably one of vertical lenticular lens surfaces that distribute light in the vertical direction.

According to this configuration, since the lenticular lens surface superimposed on the horizontal linear Fresnel lens surface or the vertical linear Fresnel lens surface is either a horizontal lenticular lens surface or a vertical lenticular lens surface, four types are available. From the combination, a complex lens surface having a required refractive action can be formed.
In addition, a single compound lens surface provides the refractive action of the base Fresnel lens surface and the refracting action of the superimposed lenticular lens surface, so the configuration is simple and aberrations are also suppressed. Can do.
Therefore, according to the present invention, it is possible to provide a transmissive screen capable of projecting a clear image with a simple configuration.

  The screen according to the present invention includes a horizontal compound lens surface that is a horizontal linear Fresnel lens surface on which a horizontal lenticular lens surface is superimposed, and a vertical compound lens surface that is a vertical linear Fresnel lens surface on which a vertical lenticular lens surface is superimposed. It is preferable to provide.

According to this configuration, since the horizontal lenticular lens surface is superimposed on the horizontal linear Fresnel lens surface, and the vertical lenticular lens surface is superimposed on the vertical linear Fresnel lens surface, the screen has a compound refraction by four lens surfaces. It is configured with two lens surfaces having an action.
Therefore, unlike the conventional screen that achieves the refractive action of the circular Fresnel lens, the horizontal lenticular lens, and the vertical lenticular lens by the four lens surfaces, the screen of the present invention has the same function by the two lens surfaces. Can be achieved.
In addition, since the horizontal linear Fresnel lens surface and the horizontal lenticular lens surface each have a shape obtained by extending the end surface shape in the vertical direction, the composite lens is based on the horizontal linear Fresnel lens surface and the horizontal lenticular lens surface is superimposed on it. The surface also has a shape obtained by extending the end surface shape in the vertical direction. Therefore, manufacture is easy.
Therefore, according to the present invention, it is possible to provide a transmissive screen capable of projecting a clear image with a simple configuration.

  According to the screen of the present invention, the horizontal compound lens surface and the vertical compound lens surface are respectively provided on the front and back of the compound lens sheet having a flat plate shape, the horizontal compound lens surface and the vertical compound lens surface, It is preferable that they are arranged orthogonally.

According to this configuration, the horizontal compound lens surface and the vertical compound lens surface are provided on the front and back of the flat compound lens sheet, respectively, so that the horizontal compound lens surface and the vertical compound lens surface are orthogonal to each other. Therefore, the screen is composed of one composite lens sheet.
Therefore, according to the present invention, it is possible to provide a transmissive screen capable of projecting a clear image with a simple configuration.

  According to the screen of the present invention, the split pitch length of the horizontal lenticular lens surface and the vertical lenticular lens surface is equal to the split pitch length of the horizontal linear Fresnel lens surface and the vertical linear Fresnel lens surface on which the respective lens surfaces are superimposed. Or a pitch length of “1 / integer” of 1/2 or less.

According to this configuration, the division pitch length of each lenticular lens surface is equal to the division pitch length of each linear Fresnel lens surface on which each lens surface is superimposed, or a “1 / integer” pitch that is 1/2 or less. Because of the length, the lenticular lens surface is well superimposed on the linear Fresnel lens surface.
Therefore, it is possible to configure a superimposing lens surface with less aberration and excellent optical characteristics.
Therefore, according to the present invention, it is possible to provide a transmissive screen capable of projecting a clear image with a simple configuration.

  According to the screen of the present invention, a diffusing agent that diffuses incident projection light on the display surface is added to the vertical compound lens surface arranged on the display surface side, or the vertical compound lens surface It is preferable that a diffusion plate is further provided as a display surface for diffusing the projection light on the display surface.

According to this configuration, a diffusing agent is added to the vertical compound lens surface arranged on the display surface side, or a diffusion plate as a display surface is further provided on the vertical compound lens surface. An image with uniform brightness and improved visual dependency is displayed on the surface.
Therefore, according to the present invention, it is possible to provide a transmissive screen capable of projecting a clear image with a simple configuration.

  In order to achieve the above object, a screen of the present invention is a transmissive screen including a back surface on which projection light from a projection device is incident and a display surface on which an image by the projection light is projected. A horizontal linear Fresnel lens surface that condenses the horizontal component of the projection light into a parallel light beam that is substantially perpendicular to the display surface, and a parallel light beam that condenses the vertical component of the projection light and is substantially perpendicular to the display surface A plurality of microscopic surfaces that distribute projection light to at least one of the two lens surfaces, or one of the two lens surfaces, the vertical linear Fresnel lens surface. The lens is superimposed to form a compound lens surface.

According to this configuration, since the plurality of microlenses for distributing the projection light are further superimposed on at least one lens surface among the provided lens surfaces, a composite lens surface is obtained. Has a refractive action of two lens surfaces by one lens surface.
Thus, unlike the conventional screen configuration, which is composed of three to four lens surfaces, a horizontal linear Fresnel lens surface, a vertical linear Fresnel lens surface, a horizontal lenticular lens surface, and preferably a vertical lenticular lens surface, The screen of the present invention can achieve the same function by two compound lens surfaces.
Furthermore, since the screen can be configured with a small number of compound lens surfaces, the effects of manufacturing variations due to the large number of lens surfaces and the effects of assembly accuracy can be reduced, so that the desired optical performance with less aberration can be obtained. .
Therefore, according to the present invention, it is possible to provide a transmissive screen capable of projecting a clear image with a simple configuration.

  In order to achieve the above object, a screen of the present invention is a transmissive screen including a back surface on which projection light from a projection device is incident and a display surface on which an image by the projection light is projected. A circular Fresnel lens surface that condenses the projection light into a parallel light beam that is substantially perpendicular to the display surface, and a plurality of microlenses that distribute the projection light are superimposed on the surface of the circular Fresnel lens surface. It is characterized by being a surface.

According to this configuration, since the plurality of microlenses for distributing the projection light are superimposed on the circular Fresnel lens surface to form a compound lens surface, the compound lens surface is composed of two lenses by one lens surface. The surface has a refractive action.
Thus, unlike the conventional screen configuration, which is composed of three to four lens surfaces, a horizontal linear Fresnel lens surface, a vertical linear Fresnel lens surface, a horizontal lenticular lens surface, and preferably a vertical lenticular lens surface, The screen of the present invention can achieve the same function by two compound lens surfaces.
Furthermore, since the screen can be configured with a small number of compound lens surfaces, the effects of manufacturing variations due to the large number of lens surfaces and the effects of assembly accuracy can be reduced, so that the desired optical performance with less aberration can be obtained. .
Therefore, according to the present invention, it is possible to provide a transmissive screen capable of projecting a clear image with a simple configuration.

  According to the screen of the present invention, the vertical linear Fresnel lens surface on which the micro lens surface is superimposed, the horizontal linear Fresnel lens surface, or the display surface side of the circular Fresnel lens surface, It is preferable that a light shielding plate which is a light shielding mask having a plurality of openings according to the arrangement is provided.

According to this configuration, the display surface side of the vertical linear Fresnel lens surface, the horizontal linear Fresnel lens surface, or the circular Fresnel lens surface on which the microlens surface is superimposed is matched with the arrangement of each superimposed microlens. In addition, since the light shielding plate, which is a light shielding mask having a plurality of openings, is provided, external light incident from the display surface side is blocked by the light shielding plate.
Therefore, since the incidence of external light can be reduced by the light shielding plate, the contrast of the image displayed on the display surface can be improved.
Therefore, according to the present invention, it is possible to provide a transmissive screen capable of displaying a clear image.

  According to the screen of the present invention, on the display surface side of the light shielding plate, there is provided a diffusion plate that is a flat plate constituting the display surface and diffuses the projection light emitted from the opening of the light shielding plate. Is preferred.

According to this configuration, the display surface side of the light shielding plate is provided with the diffusion plate that diffuses the projection light emitted from the opening of the light shielding plate, which is a flat plate constituting the display surface. An image with uniform brightness and improved visual dependency is displayed on the surface.
Therefore, according to the present invention, it is possible to provide a transmissive screen capable of displaying a clear image.

  In order to achieve the above object, a rear projection display device of the present invention modulates light emitted from a screen and a light source into modulated light representing an image corresponding to an image signal by a light modulation element, and converts the modulated light. A projection apparatus that emits the enlarged projection light and a reflection optical unit that reflects the projection light and enters the back surface of the screen are provided.

According to this configuration, since the projection device of the rear projection display device includes the light modulation element, the light emitted from the light source unit can be efficiently converted into modulated light representing an image.
In addition, the rear projection display device includes a transmissive screen that can display a clear image with a simple configuration.
Therefore, according to the present invention, it is possible to provide a rear projection display device capable of projecting a clear image with a simple configuration.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(Embodiment 1)
<Outline of rear projector>
FIG. 1 is a schematic configuration diagram of a rear projector in an embodiment of the present invention.
A rear projector 100, which is a rear projection display device, expands the projection light L representing an image emitted from the built-in projection device 11, and projects the image on a transmissive screen 13 provided.
The rear projector 100 includes a reflection mirror 12 as a reflection optical unit in addition to the projection device 11 and the screen 13.
The reflection mirror 12 is a substantially flat plane mirror that totally reflects the projection light L about the optical axis Lc emitted from the projection device 11 and makes it incident on the back surface Sb of the screen 13. The reflection mirror 12 is configured by forming a highly reflective thin film layer such as aluminum or a dielectric multilayer film layer on the surface of a hard synthetic resin such as acrylic resin or glass.

The projection light L totally reflected by the reflection mirror 12 enters the back surface Sb of the screen 13 and projects an image on the display surface Sf of the screen 13.
In FIG. 1, the projection light L is incident with the optical axis Lc being substantially perpendicular (incident angle≈0 °) with respect to the screen 13 surface, but this is not restrictive. For example, it is possible to increase the incident angle of the projection light L with respect to the surface of the screen 13 and reduce the depth size of the rear projector 100 by adding one more reflecting mirror to the configuration of the reflecting optical unit. Alternatively, by using a reflection mirror including a curved surface, the incident angle may be changed and image formation may be corrected.
When the incident angle of the projection light L is increased, it is necessary that a later-described linear Fresnel lens surface on the back surface Sb of the screen 13 is matched with the incident angle.

<Projector overview>
FIG. 2 is a schematic configuration diagram centering on the optical unit of the projection apparatus.
The projection device 11 separates the light W emitted from the lamp 51, which is a light source, into three primary color components of red light R, green light G, and blue light B, and a liquid crystal for each color light as a light modulation element for each color light. This is a so-called “liquid crystal three-plate projector” that modulates the light valve 65R, 65G, 65B according to the image signal and enlarges and projects the combined full-color modulated light onto the screen 13 by the projection lens 68.
The projection device 11 includes an optical unit 50, a circuit unit 70, and the like.
The lamp 51 is a lamp capable of obtaining high brightness such as a high-pressure mercury lamp, a metal halide lamp, and a halogen lamp.

<Outline of optical section>
In addition to the lamp 51, the liquid crystal light valves 65R, 65G, and 65B and the projection lens 68, the optical unit 50 includes an integrator 52, a polarization conversion element 53, reflection mirrors 54, 56, 59, 61, and 67, and a red light transmission dichroic. It includes a mirror 55, a blue light transmitting dichroic mirror 57, relay lenses 58 and 60, a cross dichroic prism 66, and the like.
The integrator 52 has a configuration in which optical systems in which small lenses having a substantially rectangular outline as viewed from the illumination optical axis direction are arranged in a matrix form face each other, and the illuminance distribution of the light W from the lamp 51 is substantially uniform. To. Similarly, a configuration using a lot integrator having a function of making the illuminance distribution uniform may be used.
The polarization conversion element 53 is an optical element that converts light composed of two types of polarization components whose illuminance distribution is made uniform by the integrator 52 into one type of polarized light that can be modulated by the liquid crystal light valves 65R, 65G, and 65B. is there. Thereby, the utilization efficiency of light is improved.

The reflection mirror 54 reflects the light W converted into one type of polarized light by the polarization conversion element 53 toward the red light transmitting dichroic mirror 55 side.
The red light transmitting dichroic mirror 55 is an optical element including a dielectric multilayer film that reflects green light G and blue light B and transmits red light R, transmits red light R, and transmits green light G and blue light. B is reflected to the blue light transmitting dichroic mirror 57 side.
The reflection mirror 56 reflects the red light R transmitted through the red light transmission dichroic mirror 55 and makes it incident on the liquid crystal light valve 65R.
The blue light transmitting dichroic mirror 57 is an optical element including a dielectric multilayer film that transmits the blue light B and reflects the green light G. The blue light transmitting dichroic mirror 57 transmits the blue light B and reflects the green light G. The reflected green light G enters the liquid crystal light valve 65G.

The blue light B transmitted through the blue light transmitting dichroic mirror 57 is reflected by the reflecting mirror 59 via the relay lens 58 and further reflected by the reflecting mirror 61 via the relay lens 60, and then is reflected on the liquid crystal light valve 65B. Incident.
The relay lenses 58 and 60 have an action of preventing the attenuation of the light amount, and prevent the attenuation of the blue light B that passes through the optical path longer than the optical paths of the red light R and the green light G.
The cross dichroic prism 66 synthesizes modulated light representing an image for each color light emitted from the three liquid crystal light valves 65R, 65G, and 65B by two cross dichroic films 66a and 66b provided in a substantially X shape. Modulated light representing a full color image is emitted.
The cross dichroic film 66a is a dielectric multilayer film that reflects red light R and transmits green light G and blue light B, and the cross dichroic film 66b reflects blue light B and reflects red light R and green light. It is a dielectric multilayer film that transmits light G.

The reflection mirror 67 reflects the modulated light combined by the cross dichroic prism 66 to the projection lens 68 side.
The projection lens 68 as a projection unit is composed of a plurality of lenses, and emits projection light having a wide angle of modulated light to the upper surface side of the projection device 11. The emitted projection light is incident on the reflection mirror 12 of FIG. The reflection mirror 67 may be provided in the projection lens 68.
The modulated light modulated by the liquid crystal light valves 65R, 65G, and 65B having a plurality of pixels corresponding to the inherent resolution and the projection light obtained by enlarging the modulated light represent portions of the plurality of pixels. It can be captured as a bundle of projection light. For example, when the resolution is XGA (1024 × 768), the partial projection light corresponding to 786,432 pixels and when the resolution is SXGA (1280 × 1024) can be captured as a bundle of light beams.

<Outline of circuit section>
Next, an outline of the circuit unit 70 of the projection device 11 will be described.
The circuit unit 70 is suitable for displaying on the liquid crystal light valves 65R, 65G, and 65B by applying a plurality of image processing to an image signal representing an input image, and a power supply unit that supplies power to each unit of the rear projector 100. An image processing unit for generating the image signal, a liquid crystal driver for driving each liquid crystal light valve by the image signal generated by the image processing unit, and a control unit for controlling the functions of each unit and the entire rear projector 100 (not shown) )) Is included.
In addition to the scaling function that adjusts the resolution without changing the screen shape of the image, the image processing by the image processing unit is caused by the large incident angle of the projected light on the screen (also referred to as “tilt angle”). A trapezoid correction process for correcting trapezoidal distortion of a projected image to be performed is also included.

<About superimposing the lens surface on the screen>
FIG. 3 is a perspective view showing one aspect of a typical lens surface used for the screen. FIG. 4A is a cross-sectional view showing the lens surface superposition principle. FIG. 4B is a cross-sectional view of the compound lens surface.
Here, the types of lens surfaces used for the screen 13 and the superimposition of lens surfaces, which is a characteristic point of the present invention, will be described with reference to FIGS. 3, 4A, and 4B.
FIG. 3 shows a horizontal linear Fresnel lens sheet 31 having a horizontal linear Fresnel lens surface 32 and a horizontal lenticular lens sheet 35 having a horizontal lenticular lens surface 36 as lens surfaces used for the screen.
The horizontal linear Fresnel lens surface 32 is obtained by dividing a semi-cylindrical horizontal linear lens surface 33 that collects light in the horizontal direction by a division pitch length p and aligning it substantially flat. Moreover, the back surface of the horizontal linear Fresnel lens sheet 31 when the horizontal linear Fresnel lens surface 32 is the front surface is a flat surface.
The horizontal linear Fresnel lens sheet 31 has a shape obtained by extending the end surface shape 31d in the vertical direction (Y-axis direction).

On the horizontal lenticular lens surface 36, a plurality of small kamaboko-shaped lenses 37 that distribute light in the horizontal direction (X-axis direction) are arranged at a division pitch length p / 2. Further, the back surface of the horizontal lenticular lens sheet 35 when the horizontal lenticular lens surface 36 is the front surface is a flat surface.
The horizontal lenticular lens sheet 35 has a shape obtained by extending the end surface shape 35d in the vertical direction (Y-axis direction).
Thus, since both the horizontal linear Fresnel lens sheet 31 and the horizontal lenticular lens sheet 35 have the end face shape 31d or the end face shape 35d extended in the vertical direction, the end face shape 31d or the end face shape 35d is defined as a mold shape. It has the feature that it can be easily manufactured by extrusion molding.
When the horizontal linear Fresnel lens sheet 31 is rotated by 90 ° along the lens surface, the lens surface becomes a vertical linear Fresnel lens surface. Similarly, when the horizontal lenticular lens sheet 35 is rotated by 90 ° along the lens surface, the lens surface becomes a vertical lenticular lens surface.

In FIG. 3, a horizontal linear Fresnel lens surface 32 and a horizontal lenticular lens surface 36 are two independent lens surfaces provided on each lens sheet. However, in the screen 13 of the present invention, one lens surface is used. A horizontal lenticular lens surface 36 is superimposed on a certain horizontal linear Fresnel lens surface 32.
FIG. 4A shows the superposition principle of the lens surface, and a horizontal compound linear lens in which a kamaboko lens 37 of a horizontal lenticular lens surface is superimposed on a horizontal linear lens surface 33 which is a base of a horizontal linear Fresnel lens surface. The state of the surface 38 is shown. FIG. 4B shows a horizontal compound lens surface 39 obtained by planarizing the horizontal compound linear lens surface 38 of FIG. 4A with a divided pitch length p. For the sake of simplicity, the split pitch length of the semi-cylindrical lens 37 is set to the same split pitch length p as that of the horizontal linear Fresnel lens 33 surface.

The horizontal compound lens surface 39 is a lens surface obtained by synthesizing two lens surfaces of a horizontal linear Fresnel lens surface and a horizontal lenticular lens surface. Therefore, the refractive action of two lens surfaces combined by one lens surface is obtained. Have.
Specifically, the horizontal compound lens surface 39 condenses the horizontal component of the projection light that is incident on the back surface of the screen 13 while being magnified to form a parallel light beam that is substantially perpendicular to the screen surface. It has the effect of distributing light in the horizontal direction.

FIG. 5 is a cross-sectional view of a compound lens surface of a different mode.
On the horizontal compound lens surface 40, a plurality of semi-cylindrical lenses 37 having a divided pitch length (p / 2) are superimposed on the divided pitch length p of the horizontal linear Fresnel lens surface as a base.
As described above, the division pitch length of the semi-cylindrical lens 37 on the horizontal lenticular lens surface is equal to or equal to or less than 1/2 of “1 / integer” of the division pitch length p of the horizontal linear Fresnel lens surface serving as a base. It is desirable to design as follows.
As a result, the semi-cylindrical lens 37 fits well within the division pitch length p of the horizontal linear Fresnel lens surface as the base.

《Composite lens design method》
FIG. 6A is a diagram showing a design mode in one mode when a lenticular lens surface is superimposed on a linear lens surface. FIG.6 (b) is an enlarged view of the principal part of the said design aspect.
Here, with reference to FIGS. 6A and 6B, the design method for superimposing the semi-cylindrical lens 37 of the lenticular lens surface on the horizontal linear lens surface 33 will be described with reference to FIG. 4A as appropriate. To do.
FIG. 6A shows a dimensional relationship when the lenticular lens surface is overlapped on the horizontal linear lens surface 33 in FIG. 4A.
The horizontal linear lens surface 33 is shown as an arc of radius “R” centered on the origin “0”.
On the circular arc of the horizontal linear lens surface 33, a semi-cylindrical lens 37 having a radius “rM” centered on the center point “C” is provided. In addition, an angle formed by a straight line connecting the origin “0” of the horizontal linear lens surface 33 to the center point “C” of the semi-cylindrical lens 37 and the x axis is expressed as an angle “θ”.

FIG. 6B is an enlarged view of the vicinity of the semi-cylindrical lens 37 in FIG. 6A, and the projecting length of the semi-cylindrical lens 37 from the horizontal linear lens surface 33 is a projecting height “e”. In FIG. 6B, since the radius “R” of the horizontal linear lens surface 33 is very large compared to the radius “rM” of the semi-cylindrical lens 37, the horizontal linear lens surface 33 is a straight line (inclined surface). I consider it.
Here, the intersection of the straight line passing through the center point “C” of the circle from the origin “0” of the horizontal linear lens surface 33 and the horizontal linear lens surface 33 and the horizontal linear lens surface 33 is the intersection “J”. The intersection of the lens 37 and the horizontal linear lens surface 33 is defined as an intersection “K”. In addition, an angle formed by a straight line connecting the intersection “J” and the center point “C” and a straight line connecting the center point “C” and the intersection point “K” is an angle “α”, and the intersection “J” and the center point “ The x coordinate dimension up to “C” is defined as an offset amount “Δ”.
Further, the protrusion width of the semi-cylindrical lens 37 from the horizontal linear lens surface 33 is defined as a protrusion width “T” captured by the length of the horizontal linear lens surface 33 and a protrusion width “t” captured as a dimension in the x-axis direction. To express.

Let's sort out the above relationships.
First, the horizontal linear lens surface 33 in FIG. 6A is represented by the formula (f1).

式（ｆ１）を、ｙを求める式に展開すると、式（ｆ２）となる。

When formula (f1) is expanded into a formula for obtaining y, formula (f2) is obtained.

式（ｆ２）をｘで微分して水平リニアレンズ面３３の傾きを求めると、式（ｆ３）となる。

When the inclination of the horizontal linear lens surface 33 is obtained by differentiating Expression (f2) by x, Expression (f3) is obtained.

上記式（ｆ３）を用いて、水平リニアレンズ面３３の原点「０」からかまぼこ状レンズ３７の中心点「Ｃ」を結ぶ直線と、ｘ軸との成す角度θを求めると、式（ｆ４）となる。

Using the above equation (f3), when the angle θ formed by the straight line connecting the origin “0” of the horizontal linear lens surface 33 to the center point “C” of the semi-cylindrical lens 37 and the x axis is obtained, the equation (f4) It becomes.

続いて、図６（ｂ）を用いて説明する。
中心点「Ｃ」、および交点「Ｊ」、交点「Ｋ」による三角形ＣＪＫは、交点「Ｊ」の内角が直角である直角三角形であることから、三平方の定理により式（ｆ５）が求められる。

Next, description will be made with reference to FIG.
The triangle CJK by the center point “C”, the intersection point “J”, and the intersection point “K” is a right triangle whose inner angle of the intersection point “J” is a right angle. Therefore, the equation (f5) is obtained by the three-square theorem. .

式（ｆ５）を、水平リニアレンズ面３３からのかまぼこ状レンズ３７の突出高さ「ｅ」を求める式に展開すると、式（ｆ６）となる。

When Expression (f5) is developed into an expression for obtaining the protrusion height “e” of the semi-cylindrical lens 37 from the horizontal linear lens surface 33, Expression (f6) is obtained.

式（ｆ６）において、突出高さ「ｅ」は、半径「ｒＭ」より小さいので正負符号は負（−）を採用する。また、かまぼこ状レンズ３７の水平リニアレンズ面３３からの突出幅「Ｔ」と、ｘ軸方向の寸法として捕らえた突出幅「ｔ」との関係は、式（ｆ７）として表される。

In the formula (f6), since the protrusion height “e” is smaller than the radius “rM”, the sign (−) is used as the sign. In addition, the relationship between the protrusion width “T” of the semi-cylindrical lens 37 from the horizontal linear lens surface 33 and the protrusion width “t” captured as the dimension in the x-axis direction is expressed as Expression (f7).

式（ｆ６）に、式（ｆ７）を代入すると、突出高さ「ｅ」は、式（ｆ８）として表される。

When the formula (f7) is substituted into the formula (f6), the protrusion height “e” is expressed as the formula (f8).

また、交点「Ｊ」と中心点「Ｃ」までのｘ座標寸法であるオフセット量「Δ」は、式（ｆ９）として表される。

Further, an offset amount “Δ” that is an x-coordinate dimension between the intersection “J” and the center point “C” is expressed as Expression (f9).

式（ｆ９）に、式（ｆ８）を代入して整理すると、式（ｆ１０）が求められる。

When formula (f8) is substituted into formula (f9) and rearranged, formula (f10) is obtained.

複合レンズ面を設計する際には、このようにして求められた関係式を用いて、以下の手順にて行うことが望ましい。
（１）手順１として、複合レンズ面に必用な視野角依存特性に応じて、かまぼこ状レンズ３７の半径「ｒＭ」を決める。
（２）水平リニアレンズ面３３をフレネルレンズ化する際の分割ピッチ長さに応じて、突出幅「ｔ」を決定する。
（３）突出幅「ｔ」を複合レンズ面の分割ピッチ長さ内における正射影の分割ピッチ長さとして、中心のかまぼこ状レンズ３７を１番目とし、ｎ番目のかまぼこ状レンズ３７の中心点「Ｃ」のｘ座標を、式（ｆ１１）の位置に設定する。

When designing a complex lens surface, it is desirable to perform the following procedure using the relational expression thus obtained.
(1) As a procedure 1, the radius “rM” of the semi-cylindrical lens 37 is determined according to the viewing angle dependency characteristic necessary for the compound lens surface.
(2) The protrusion width “t” is determined according to the division pitch length when the horizontal linear lens surface 33 is formed into a Fresnel lens.
(3) The protrusion width “t” is the division pitch length of the orthogonal projection within the division pitch length of the compound lens surface, the central kamaboko lens 37 is the first, and the center point “n” of the nth kamaboko lens 37 The x coordinate of “C” is set to the position of the formula (f11).

（４）角度「θ」を、式（ｆ４）により求める。
（５）突出高さ「ｅ」を、式（ｆ８）により求める。
（６）オフセット量「Δ」を、式（ｆ１０）により求める。

(4) The angle “θ” is obtained by the equation (f4).
(5) The protrusion height “e” is obtained by the equation (f8).
(6) The offset amount “Δ” is obtained by the equation (f10).

The superposition shape of the semi-cylindrical lens 37 on the horizontal linear lens surface 33 in FIG. Then, the mold processed along the determined overlapping shape is divided for each division pitch length p and flattened, thereby forming the compound lens surface shown in FIG. 4B or FIG. A mold can be manufactured. In addition, machining methods, such as cutting and electric discharge machining, can be used for machining the mold.
In addition, a compound lens may be directly formed by processing a lens material such as acrylic resin or glass by the above method.

<< Schematic configuration of first screen >>
FIG. 7 is a schematic configuration diagram of a first screen in the first embodiment. Here, the configuration of the screen 13 as the first screen of the present invention will be described with reference to FIG.
The screen 13 includes a horizontal linear Fresnel lens sheet 3 and a vertical linear Fresnel lens sheet 5.

The horizontal linear Fresnel lens sheet 3 includes a horizontal compound lens surface 2 as a back surface Sb of the screen 13. Further, the back surface when the horizontal compound lens surface 2 is the front surface is a flat surface.
The horizontal compound lens surface 2 is a compound such as the horizontal compound lens surface 39 in FIG. 4B or the horizontal compound lens surface 40 in FIG. 5 in which a horizontal lenticular lens surface is superimposed on a horizontal linear Fresnel lens surface. It is a lens surface.
The vertical linear Fresnel lens sheet 5 includes a vertical compound lens surface 4 as a display surface Sf of the screen 13. Further, the back surface when the vertical compound lens surface 4 is the front surface is a flat surface.
The vertical compound lens surface 4 is a compound lens surface in which a vertical lenticular lens surface is superimposed on a vertical linear Fresnel lens surface. The vertical compound lens surface 4 is equivalent to the surface obtained by turning the horizontal compound lens surface 2 upside down and rotating 90 ° along the lens surface.
The horizontal compound lens surface 2 and the vertical compound lens surface 4 are designed using the design procedure described in FIGS. 6A and 6B according to the resolution of the projection light L emitted from the projection device 11 in FIG. Two lens surfaces are superimposed.

As the material of the horizontal linear Fresnel lens sheet 3 and the vertical linear Fresnel lens sheet 5, for example, an acrylic resin having excellent optical characteristics and molding processability is used. Note that the resin is not limited to an acrylic resin, and may be a polycarbonate resin, an olefin resin, a styrene resin, or the like as long as it is a transparent synthetic resin for optics.
The horizontal linear Fresnel lens sheet 3 and the vertical linear Fresnel lens sheet 5 have shapes obtained by extending the respective end surface shapes 3d and 5d. For this reason, the lens sheet can be easily manufactured by extruding these synthetic resins using a mold having end face shapes 3d and 5d.
The lens sheet can also be formed by a processing method such as hot pressing, emission molding, or roller transfer. Furthermore, when an injection mold provided so that the mold surfaces forming the horizontal compound lens surface 2 and the vertical compound lens surface 4 are opposed to each other, an integrated lens having two compound lens surfaces The sheet can be manufactured by a single injection molding.
The material of the lens sheet may be glass.

The horizontal linear Fresnel lens sheet 3 and the vertical linear Fresnel lens sheet 5 are bonded so that the flat back surfaces are in close contact with each other so that the horizontal compound lens surface 2 and the vertical compound lens surface 4 are orthogonal to each other.
Further, in the vicinity of the vertical compound lens surface 4 inside the vertical linear Fresnel lens sheet 5, a diffusing agent 7 having a function of diffusing light is mixed with a uniform dispersion degree. The diffusing agent 7, for _{example, SIO 2, CaCO 3, Al} 2 O 3, TIO 3, BaSO 4, ZnO or the like is used glass powder.

Next, an aspect of a projection image by the projection light L incident on the screen 13 having such a configuration will be described.
The projection light L that is incident on the horizontal compound lens surface 2 of the screen 13 while spreading radially, emits a principal ray substantially perpendicular to the screen surface due to the condensing action by the Fresnel components of the horizontal compound lens surface 2 and the vertical compound lens surface 4. It becomes a dispersion distribution light beam.
Further, the light is distributed and diffused on the vertical compound lens surface 4 as the display surface Sf by the diffusing action of the horizontal compound lens surface 2, the vertical compound lens surface 4 and the diffusing agent 7, and the bright dependency is improved. Project an image.
Since the main role of the lenticular lens surface is to improve visual dependency in the horizontal direction, for example, a configuration in which the horizontal lenticular lens surface is superimposed only on the horizontal compound lens surface 2 may be used. In this case, the diffusing agent 7 is responsible for improving the visual dependency in the vertical direction, and the vertical linear Fresnel lens sheet 5 is provided with only the vertical linear Fresnel lens surface in which the diffusing agent 7 is blended.

As described above, according to the present embodiment, the following effects can be obtained.
(1) Since at least one of the horizontal compound lens surface 2 and the vertical compound lens surface 4 is superposed with a lenticular lens surface that diffuses the projection light L on the display surface Sf, the screen 13 It is constituted by two lens surfaces having a compound refraction action by at least three lens surfaces.
Therefore, the screen 13 can achieve the condensing and light distribution functions of the projection light L by the two lens surfaces.
Furthermore, since the horizontal linear Fresnel lens sheet 3 and the vertical linear Fresnel lens sheet 5 have simple shapes obtained by extending the respective end surface shapes 3d and 5d, they are easy to manufacture. In addition, since there are two lens surfaces, the influence of manufacturing variations due to the large number of lens surfaces and the influence of assembly accuracy can be reduced, so that the desired optical performance with less aberration can be obtained.
Therefore, it is possible to provide a transmission screen 13 that can display a clear image with a simple configuration.

(2) The horizontal compound lens surface 2 is a compound lens surface in which a horizontal linear Fresnel lens surface and a horizontal lenticular lens surface are superimposed, and the vertical compound lens surface 4 includes a vertical linear Fresnel lens surface and a vertical lenticular lens surface. Since the compound lens surfaces are superposed, the screen 13 is composed of two compound lens surfaces having a compound refraction action by the four lens surfaces.
Therefore, the screen 13 achieves the refractive action by the circular Fresnel lens, the horizontal lenticular lens, and the vertical lenticular lens by the two lens surfaces of the horizontal compound lens surface 2 and the vertical compound lens surface 4.
Therefore, it is possible to provide a transmission screen 13 that can display a clear image with a simple configuration.

(3) A “1 / integer” that is equal to or less than or equal to ½ of the division pitch length p of the semi-cylindrical lens 37 on the horizontal lenticular lens surface with respect to the division pitch length p of the horizontal linear Fresnel lens surface serving as a base. By doing so, the semi-cylindrical lens 37 can be stored in the divided pitch length p with good separation of the lens surfaces.
Therefore, it is possible to configure a superimposing lens surface with less aberration and excellent optical characteristics.
Therefore, it is possible to provide a transmission screen 13 that can display a clear image with a simple configuration.

(4) The horizontal linear Fresnel lens sheet 3 and the vertical linear Fresnel lens sheet 5 are arranged so that the back surfaces which are planes are in close contact with each other and the horizontal compound lens surface 2 and the vertical compound lens surface 4 are orthogonal to each other. Thus, an integrated lens sheet is obtained.
Therefore, the function of at least three lens sheets, that is, a horizontal linear Fresnel lens sheet, a vertical linear Fresnel lens sheet, and a horizontal lenticular lens sheet can be achieved by this integrated lens sheet.
Therefore, it is possible to provide a transmission screen 13 that can display a clear image with a simple configuration.

(5) In the vicinity of the vertical compound lens surface 4 inside the vertical linear Fresnel lens sheet 5, the diffusing agent 7 having the function of diffusing light is mixed in with a uniform dispersion degree, so that the display surface Sf is bright. An image with a uniform thickness and improved visual dependency is displayed.
Further, since a diffusion plate is not required, the configuration is simple.
Therefore, it is possible to provide a transmission screen 13 that can display a clear image with a simple configuration.

(6) Since the projection device 11 of the rear projector 100 includes the liquid crystal light valves 65R, 65G, and 65B, which are transmissive liquid crystal panels, as light modulation elements, the light emitted from the lamp 51 is efficiently converted into modulated light that represents an image. Can be converted. Therefore, a clear projected image can be obtained.
The rear projector 100 includes a transmissive screen 13 that can display a clear image with a simple configuration.
Therefore, it is possible to provide the rear projector 100 capable of projecting a clear image with a simple configuration.

(Embodiment 2)
<< Schematic configuration of second screen >>
FIG. 8 is a schematic configuration diagram of a second screen according to the second embodiment of the present invention.
The screen 23 as the second screen has a configuration suitable as a screen of the rear projector 100. Here, a schematic configuration of the screen 23 will be described with reference to FIG.
In addition, the same number is attached | subjected about the component same as the screen 13 of Embodiment 1, and the overlapping description is abbreviate | omitted.

The screen 23 includes a vertical Fresnel microlens sheet 8, a light shielding plate 16, a diffusion plate 17 and the like in addition to the horizontal linear Fresnel lens sheet 3 described above.
In FIG. 8, the space between the vertical Fresnel microlens sheet 8 and the light shielding plate 16 is a space for the sake of drawing, but the actual screen is in close contact. Similarly, the light shielding plate 16 and the diffusion plate 17 are also in close contact with each other.
The vertical Fresnel microlens sheet 8 includes a vertical compound lens surface 9. Further, the back surface when the vertical compound lens surface 9 is the front surface is a flat surface.
The vertical compound lens surface 9 is a compound lens surface in which a plurality of microlenses 15 that distribute the projection light L in the vertical direction on the display surface Sf are superimposed on the vertical linear Fresnel lens surface.
The vertical Fresnel microlens sheet 8 is made of the same material as that of the horizontal linear Fresnel lens sheet 3, and is formed integrally with the horizontal linear Fresnel lens sheet 3 with its back surfaces in close contact with each other. In order to integrate them, a method of bonding the vertical Fresnel microlens sheet 8 and the horizontal linear Fresnel lens sheet 3 can be used. Alternatively, an integral lens provided with two compound lens surfaces using an injection mold provided so that the mold surfaces forming the horizontal compound lens surface 2 and the vertical compound lens surface 9 face each other. The sheet may be manufactured by one injection molding.
The vertical compound lens surface 9 has an optimal optical design such as the size and arrangement of the plurality of microlenses 15 according to the resolution of the projection light L emitted from the projection device 11 of FIG. 1, and the two lens surfaces are superimposed. ing.

The light shielding plate 16 is a light shielding mask having a plurality of openings in accordance with the arrangement of the plurality of microlenses 15 on the vertical compound lens surface 9. The light shielding plate 16 is made of an all-black synthetic resin plate, a thin metal plate, or the like, and is provided with a plurality of openings by pressing.
The light shielding plate 16 allows the partially projected light collected for each of the plurality of microlenses 15 to pass through the corresponding plurality of openings and absorbs external light incident from the display surface Sf.
The diffusion plate 17 constitutes the display surface Sf and diffuses the projection light emitted from the opening of the light shielding plate 16. The diffusing plate 17 is configured, for example, by mixing the diffusing agent 7 with a uniform degree of dispersion in a translucent synthetic resin plate.

Next, an aspect of a projected image by the projection light L incident on the screen 23 having such a configuration will be described.
The projection light L that is incident on the horizontal compound lens surface 2 of the screen 23 while spreading radially, emits a principal ray substantially perpendicular to the screen surface due to the condensing action by the Fresnel components of the horizontal compound lens surface 2 and the vertical compound lens surface 9. It becomes a dispersion distribution light beam.
Further, by the diffusing action of the horizontal compound lens surface 2, the vertical compound lens surface 9, and the diffusion plate 17, light is distributed and diffused on the display surface Sf, and a bright image with improved visual dependency is displayed. Further, external light incident from the display surface Sf is absorbed by the light shielding plate 16.
The plurality of microlenses 15 may be configured to diffuse light in both the horizontal and vertical directions, and the horizontal compound lens surface 2 may be configured to include only a horizontal linear Fresnel lens surface. Even in this configuration, a practically sufficient diffusion effect can be obtained on the display surface Sf by the action of the light shielding plate 16 and the diffusion plate 17.

Further, since the visual dependency in the horizontal direction on the screen 23 is a direction to be improved as compared with the vertical direction, for example, the shape of the microlens 15 may be an elliptical rotation shape that is long in the vertical direction. According to this configuration, the horizontal light distribution degree of the projection light on the display surface Sf can be increased more than the vertical direction.
In order to further increase the degree of light distribution in the horizontal direction, the division pitch length of the lenticular lens surface of the horizontal compound lens surface 2 may be shortened. Further, the degree of diffusion in the horizontal direction may be increased by adjusting the composition of the diffusing agent in the diffusing plate 17.

As described above, according to the present embodiment, the following effects can be obtained in addition to the corresponding effects of the first embodiment.
(1) The horizontal compound lens surface 2 is a compound lens surface in which a horizontal linear Fresnel lens surface and a horizontal lenticular lens surface are superimposed, and the vertical compound lens surface 9 displays the projection light L on the vertical linear Fresnel lens surface. Since the surface is a compound lens surface in which a plurality of microlenses 15 that are diffused in the vertical direction on the surface Sf are superposed, the screen 23 is composed of two compound lens surfaces having a compound refraction action of four lens surfaces.
Therefore, the screen 23 achieves the refraction action by the circular Fresnel lens, the horizontal lenticular lens, and the vertical lenticular lens by the two lens surfaces of the horizontal compound lens surface 2 and the vertical compound lens surface 9.
Therefore, it is possible to provide a transmissive screen 23 that can display a clear image with a simple configuration.

(2) The light shielding plate 16 allows the partial projection light collected for each of the plurality of microlenses 15 to pass through the corresponding plurality of openings and absorbs external light incident from the display surface Sf. External light incident from the surface Sf is blocked by the light shielding plate 16.
Therefore, since the incidence of external light can be reduced by the light shielding plate 16, the contrast of the image displayed on the display surface Sf can be improved.
Therefore, it is possible to provide a transmissive screen 23 that can display a clear image.

(3) The diffusion plate 17 constitutes the display surface Sf and diffuses the projection light emitted from the opening of the light shielding plate 16, so that the display surface Sf has uniform brightness and improved visual dependency. The displayed image is displayed.
Therefore, it is possible to provide a transmissive screen 23 that can display a clear image.

(4) The screen 23 is suitable for the rear projector 100 because it is a transmissive screen capable of projecting a clear image.
Therefore, it is possible to provide the rear projector 100 capable of projecting a clear image with a simple configuration.

  Note that the present invention is not limited to the above-described embodiment, and various modifications and improvements can be added to the above-described embodiment. A modification will be described below.

(Modification 1)
FIG. 9A is a perspective view showing one aspect of the horizontal Fresnel lens sheet and the vertical lenticular lens in Modification 1. FIG. FIG. 9B is a perspective view of the compound lens surface.
In the first embodiment, the horizontal compound lens surface 39 in FIG. 4B and the horizontal compound lens surface 40 in FIG. 5 are compound lens surfaces in which a horizontal lenticular lens surface is superimposed on a horizontal Fresnel lens surface. However, the present invention is not limited to this combination. For example, the vertical lenticular lens surface may be superimposed on the horizontal Fresnel lens surface.
In FIG. 9A, the horizontal linear Fresnel lens sheet 31 is provided with a horizontal linear Fresnel lens surface 32. Similarly, the vertical lenticular lens sheet 85 is provided with a vertical lenticular lens surface 86.

FIG. 9B shows a compound lens surface 88 in which a vertical lenticular lens surface 86 is superimposed on the horizontal linear Fresnel lens surface 32 of the horizontal linear Fresnel lens sheet 31. The compound lens surface 88 is a lens surface obtained by combining two lens surfaces of a horizontal linear Fresnel lens surface and a vertical lenticular lens surface, and therefore has a refractive action of two lens surfaces combined by one lens surface. is doing. Specifically, it has a horizontal light condensing function by the horizontal linear Fresnel lens surface and a vertical component light diffusing function by the vertical lenticular lens surface.
Similarly, a compound lens surface in which a horizontal lenticular lens surface is superimposed on a vertical linear Fresnel lens surface can also be formed.
Thus, according to the compound lens surface, it is possible to superimpose both lens surfaces regardless of the horizontal and vertical directions of the lens surface, and a plurality of images superimposed by one compound lens surface. The refractive action of the lens surface can be obtained.
Therefore, the screen using the compound lens can display a clear image with a simple configuration.

(Modification 2)
FIG. 10A is a front view of the compound lens surface in the second modification. FIG. 10B is a cross-sectional view of the compound lens surface.
In the second embodiment, the vertical compound lens surface 9 in FIG. 8 is a compound lens surface in which a plurality of microlenses 15 are superimposed on the vertical Fresnel lens surface, but is not limited to this combination. For example, a configuration in which a microlens is superimposed on a circular Fresnel lens surface may be used.
In FIG. 10A, the compound lens surface 96 in which a plurality of microlenses 95 are superimposed on the circular Fresnel lens surface is observed from the front. In order to increase the degree of light distribution in the horizontal direction as compared with the vertical direction, a plurality of microlenses 95 having the same shape that are long in the y-axis direction are densely arranged on the surface of the circular Fresnel lens.

FIG. 10B is a cross-sectional view of the compound lens surface 96 along the x axis. FIG. 10B shows a state in which a plurality of microlenses 95 are superimposed on the circular Fresnel lens surface 97 indicated by a dotted line to form a composite lens surface 96.
Since the compound lens surface 96 is a lens surface in which a plurality of microlenses 95 are superimposed on the circular Fresnel lens surface 97, the compound lens surface 96 has a refractive action of two lens surfaces combined by one lens surface. Specifically, the circular Fresnel lens surface 97 has a light collecting action in the horizontal and vertical directions, and the plurality of microlenses 95 have a light distribution action in the horizontal and vertical directions, respectively. The compound lens surface 96 can achieve the refractive action by the horizontal compound lens surface 2 and the vertical compound lens surface 9 of FIG.
Therefore, the screen having the compound lens surface 96 can display a clear image with a simple configuration.

(Modification 3)
This will be described with reference to FIG. In the first embodiment, the display surface Sf of the screen 13 is configured by the vertical compound lens surface 4 of the vertical linear Fresnel lens sheet 5, but is not limited thereto.
For example, a diffusion plate as the display surface Sf may be provided on the front surface of the vertical linear Fresnel lens sheet 5. In this case, it is not necessary to mix the diffusing agent 7 in the vertical linear Fresnel lens sheet 5. Moreover, as a diffusion plate, the thing equivalent to the diffusion plate 17 of FIG. 8 can be used.
According to this configuration, a clear image can be displayed, and the display surface Sf is a flat surface. Therefore, it is possible to provide a screen that is easy to care for when dust is attached.

(Modification 4)
This will be described with reference to FIG. In each of the above embodiments, the projection device 11 modulates the color light according to the image signal by the liquid crystal light valves 65R, 65G, 65B for each color light as the light modulation element, and re-synthesizes the full-color modulated light by the projection lens 68. Although the liquid crystal three-plate projector has been described as being enlarged and projected to 13, the present invention is not limited to this.
For example, the projection device 11 is configured to use a single-plate liquid crystal light valve in which red, green, and blue color filters are regularly arranged in a lattice pattern and can emit a full-color modulated light by one sheet. May be. Further, a configuration using a reflective liquid crystal display device or a tilt mirror device may be used. Note that, for example, in the case of a configuration using a tilt mirror device, the configuration of the optical unit 50 is different from the configuration of FIG. 2 depending on the light modulation element used, such that the polarization conversion element 53 is not necessary. Become.
Further, it may be a projection device having a configuration using a laser scanning optical system having a light modulation function, a spontaneous light modulation element array, or the like.
Even if it is these structures, the effect similar to each said embodiment can be acquired.

1 is a schematic configuration diagram of a rear projector in an embodiment. The schematic block diagram centering on the optical part of a projection apparatus. The perspective view which shows the one aspect | mode of the typical lens surface used for a screen. (A) Sectional drawing which shows the superimposition principle of a lens surface. (B) Sectional drawing of a compound lens surface. Sectional drawing of the compound lens surface of a different aspect. (A) The figure which shows the design aspect in one form at the time of superimposing a lenticular lens surface on a linear lens surface. (B) The enlarged view of the principal part of the said design aspect. FIG. 3 is a schematic configuration diagram of a first screen in the first embodiment. FIG. 6 is a schematic configuration diagram of a second screen in the second embodiment. (A) The perspective view which shows the one aspect | mode of the horizontal Fresnel lens sheet and vertical lenticular lens in the modification 1. FIG. (B) The perspective view of a compound lens surface. (A) The front view of the compound lens surface in the modification 2. FIG. (B) Sectional drawing of a compound lens surface. The perspective sectional view of the principal part in the conventional screen. Sectional drawing of the principal part in the screen of the conventional different aspect.

Explanation of symbols

2, 39, 40: Horizontal compound lens surface which is a horizontal linear Fresnel lens surface on which horizontal lenticular lens surfaces are superimposed, 3 ... Horizontal linear Fresnel lens sheet, 4 ... Vertical linear Fresnel lens surface on which vertical lenticular lens surfaces are superimposed A vertical compound lens surface, 5 ... a vertical linear Fresnel lens sheet, 7 ... a diffusing agent, 8 ... a vertical Fresnel micro lens sheet, 9 ... a vertical compound lens surface as a vertical linear Fresnel lens surface on which micro lens surfaces are superimposed, 11 ... Projection device, 12 ... reflection mirror as reflection optical unit, 13, 23 ... screen, 15, 95 ... plural microlenses, 16 ... light shielding plate, 17 ... diffusion plate, 32 ... horizontal linear Fresnel lens surface, 33 ... horizontal linear Lens surface, 36 ... Horizontal lenticular lens surface, 37 ... Kamaboko lens, 88 ... Suspension Compound lens surface which is a horizontal linear Fresnel lens surface on which a lenticular lens surface is superimposed, 51... Lamp as a light source, 65R, 65G, 65B... Liquid crystal light valve as a light modulation element, 100. Projector, 96: Compound lens surface that is a circular Fresnel lens surface on which a plurality of microlenses are superimposed, 97: Circular Fresnel lens surface, Sf: Display surface, Sb: Back surface, L: Projected light, Lc: Optical axis.

Claims (11)

A transmissive screen including a back surface on which projection light from a projection device is incident and a display surface on which an image of the projection light is projected;
A horizontal linear Fresnel lens surface that condenses the horizontal component of the projection light to make a parallel light beam substantially perpendicular to the display surface, and a vertical component of the projection light that is substantially perpendicular to the display surface by condensing the vertical component. Two lens surfaces with a vertical linear Fresnel lens surface that is a parallel light beam, or one of the lens surfaces,
A screen characterized in that a lenticular lens surface for distributing the projection light is superimposed on at least one of the provided lens surfaces to form a compound lens surface. The horizontal linear Fresnel lens surface, or the lenticular lens surface superimposed on the vertical linear Fresnel lens surface,
2. The screen according to claim 1, wherein the screen is either a horizontal lenticular lens surface that distributes the projection light in a horizontal direction or a vertical lenticular lens surface that distributes the projection light in a vertical direction. A horizontal compound lens surface which is the horizontal linear Fresnel lens surface on which the horizontal lenticular lens surface is superimposed;
The screen according to claim 2, further comprising: a vertical compound lens surface that is the vertical linear Fresnel lens surface on which the vertical lenticular lens surface is superimposed. The horizontal compound lens surface and the vertical compound lens surface are respectively provided on the front and back of a compound lens sheet having a flat plate shape,
The screen according to claim 3, wherein the horizontal compound lens surface and the vertical compound lens surface are disposed so as to be orthogonal to each other.   The division pitch length of the horizontal lenticular lens surface and the vertical lenticular lens surface is equal to or 1/2 of the division pitch length of the horizontal linear Fresnel lens surface and the vertical linear Fresnel lens surface on which the respective lens surfaces are superimposed. The screen according to claim 2, wherein the screen has a pitch length of “1 / integer” below.   A diffusion agent for diffusing the incident projection light on the display surface is added to the vertical compound lens surface disposed on the display surface side, or on the front surface of the vertical compound lens surface, the The screen according to claim 3 or 4, further comprising a diffusion plate as the display surface for diffusing projection light on the display surface. A transmissive screen including a back surface on which projection light from a projection device is incident and a display surface on which an image of the projection light is projected;
A horizontal linear Fresnel lens surface that condenses the horizontal component of the projection light to make a parallel light beam substantially perpendicular to the display surface, and a vertical component of the projection light that is substantially perpendicular to the display surface by condensing the vertical component. Two lens surfaces with a vertical linear Fresnel lens surface that is a parallel light beam, or one of the lens surfaces,
A screen characterized in that a plurality of microlenses for distributing the projection light are superimposed on at least one of the provided lens surfaces to form a compound lens surface. A transmissive screen including a back surface on which projection light from a projection device is incident and a display surface on which an image of the projection light is projected;
A circular Fresnel lens surface that condenses the projection light to make a parallel light beam substantially perpendicular to the display surface;
A screen characterized in that a plurality of microlenses for distributing the projection light are superimposed on the surface of the circular Fresnel lens to form a compound lens surface. On the display surface side of the vertical linear Fresnel lens surface on which the microlens surface is superimposed, the horizontal linear Fresnel lens surface, or the circular Fresnel lens surface,
The screen according to claim 7 or 8, further comprising a light shielding plate which is a light shielding mask having a plurality of openings according to the arrangement of the superposed microlenses.   The diffusion plate for diffusing projection light emitted from the opening of the light shielding plate is provided on the display surface side of the light shielding plate, which is a flat plate constituting the display surface. Item 10. The screen according to Item 9. The screen according to any one of claims 1 to 10,
A projection device that modulates light emitted from a light source into modulated light representing an image corresponding to an image signal by a light modulation element, and emits projection light obtained by enlarging the modulated light;
A rear projection display device, comprising: a reflection optical unit that reflects the projection light to enter the back surface of the screen.

Images