JP2006171482A - Screen, fresnel lens sheet for use in the same, and image display device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide technology suitable to shorten the depth of a rear projection type image display device, while obtaining an image of high image quality. <P>SOLUTION: A Fresnel lens sheet (6) is provided with a total reflection prism part (10), formed on its image generation source side and a refraction prism part formed on its image observation side. The total reflection prism part (10) includes an incidence face (15), on which light is made incident and a total reflection face (16) from which incident light from the incidence face is reflected and emitted to the image observation side; and furthermore includes elements (17 and 18) for cutting a part of the incident light so as not to have a part of light impinging on the total reflection prism part emitted to the image observation side. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image display device that enlarges and projects an image of an image generation source and displays the image on a transmissive screen, and a screen and a Fresnel lens sheet used in the image display device.

  A projection-type image display device (hereinafter sometimes referred to as “set”) is a transmissive screen in which an image displayed on a projection-type cathode ray tube or a liquid crystal display device as a small image generation source is enlarged by a projection lens or the like. An image is formed on the transmissive screen by projecting onto the transmissive screen.

  Such an image display device is required to be thin (reduced in the depth of the set) in order to reduce weight and reduce cost and installation space. As a configuration of a transmissive screen for accommodating a thinned set, for example, a configuration described in Patent Document 1 is known.

WO / 02/27399

  Thinning the set (reducing the depth dimension) reduces the projection distance by widening the projection lens, and further shifts the optical axis center of the projection lens below the center of the transmission screen (e.g., the optical axis center of the projection lens). This is possible by aligning with the center of the lower end of the transmission screen.

  However, in such a configuration, for example, when the size of the screen (aspect ratio 16: 9) is 65 inches diagonal, the projection distance of the projection lens is 500 mm, and the depth of the set is 350 mm, from the projection lens to the transmissive screen The incident angle of the image light incident on the upper left and right ends is as large as 65.2 degrees. FIG. 10 is a diagram showing the relationship between the incident angle of light on the screen and the reflection loss in a general exit surface Fresnel lens. FIG. 10 shows that when the light incident angle is 65.2 degrees, the reflection loss of the screen is as large as 36%. Therefore, when the image display apparatus is further reduced in thickness, this loss increases rapidly, and the upper left and right ends of the screen become dark.

  In Patent Document 1, as a transmissive screen corresponding to such a thin set, a refractive prism portion and a total reflection prism portion are alternately provided on a light incident surface of a Fresnel lens sheet, and a light emitting surface is provided. A flat surface is disclosed. However, the configuration described in Patent Document 1 has a configuration in which a refractive prism portion is provided on the light incident surface of the Fresnel lens sheet, so that the efficiency is lowered. In particular, a mid-range image (a donut-shaped image on the screen) that is important as an image. Range) becomes darker.

  Further, in the case where the Fresnel lens sheet is provided with the refractive prism portion and the total reflection prism portion, the transmission between the refractive prism portion and the total reflection prism portion at the boundary portion between the refractive prism portion and the total reflection prism portion. Light discontinuity may occur due to the difference in rate. When the light discontinuity occurs, a discontinuous portion is generated in the image viewed from the front, which causes a deterioration in image quality.

  In this way, in a transmissive screen corresponding to the reduction in the thickness of the image display device, the reflection loss of light on the incident surface of the screen is reduced and the light use efficiency is improved, thereby brightening the image (that is, the brightness of the image). Suppressing reduction is an important issue. In addition, suppression of light discontinuity is also an important issue.

  The present invention has been made in view of the above problems, and an object thereof is to provide a technique suitable for shortening the depth of an image display device while obtaining a high-quality image. .

  In order to achieve the above object, in the present invention, a total reflection prism is applied to an area where light is incident at a predetermined incident angle (for example, approximately 42 degrees) or more on the image generation source side (light incident surface) of the Fresnel lens sheet. And a refractive prism portion was formed on the image viewing side (light exit surface). The total reflection prism unit includes an incident surface on which light is incident and a total reflection surface that reflects incident light from the incident surface and emits the incident light toward the image viewing side. The total reflection prism unit Further, an element for cutting a part of the incident light is provided so that a part of the light incident on the total reflection type prism portion is not emitted to the image viewing side. With this element, the transmittance for light incident on the total reflection prism portion is reduced. The element may be a light shielding part that shields a part of light incident on the total reflection prism part. The element may be a reflecting surface for reflecting a part of the light incident on the total reflection type prism unit in a direction not emitted to the image viewing side.

  Further, the decrease in transmittance due to the element of the total reflection prism portion provided at the position where the incident angle is large is smaller than the decrease in transmittance due to the element of the total reflection prism portion provided at the position where the incident angle is small. You can make it bigger. Further, the total reflection type prism unit causes the incident light beam to be at least a direction substantially perpendicular to the Fresnel lens sheet and more than the total reflection angle of the Fresnel lens sheet by the total reflection phenomenon after the first refraction phenomenon. It is possible to include at least two or more surfaces, an incident surface composed of a spherical surface or an aspherical surface, and a total reflection surface, which provide two or more incident surface exit angles in the direction facing the surface.

  Preferably, the total reflection type in the vicinity of the boundary between the total reflection prism portion and the refraction type prism portion (a portion where the total reflection type prism portion and the refraction type prism portion overlap in the normal direction of the Fresnel lens sheet). The transmittances of the prism portion and the refractive prism portion are made substantially equal.

  In the present invention, when the total reflection type prism portion is formed on the image generation source side of the Fresnel lens sheet and the refraction type prism portion is formed on the image viewing side as described above, the transmittance of the total reflection type prism portion is increased. An element to lower is provided. As a result, the transmittances of the total reflection prism portion and the refractive prism portion in the vicinity of the boundary between the total reflection prism portion and the refractive prism portion can be made substantially equal. Therefore, according to the present invention, it is possible to suppress a change in the brightness of the image displayed on the screen due to the viewing angle.

  According to the present invention, it is possible to reduce the thickness of an image display device while improving image quality.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partial cross-sectional perspective view of an image display device according to the present invention. The image source 1 is composed of a projection cathode ray tube, a reflective or transmissive liquid crystal panel, an image modulation element such as a display element having a plurality of minute mirrors, and the like, and displays a small image. The projection lens 2 enlarges the image and projects it on the transmissive screen 3. Since the projection distance of the projection lens 2 is generally long, the reflection mirror 4 is provided in the middle of the optical path (the path of light from the exit side of the projection lens to the screen) in order to reduce the depth of the image display device. ing. These elements are housed inside the housing 5 and fixed in place.

  FIG. 2 is a schematic diagram showing the structure of the transmission screen 3 according to the present invention. An enlarged projection image (not shown) projected from the direction of the arrow b is converted into substantially parallel light or light slightly inward by the Fresnel lens sheet 6 and enters the lenticular lens sheet 7. As shown in the figure, the lenticular lens sheet 7 has a shape in which a plurality of lenticular lenses whose longitudinal direction is the screen screen vertical direction are arranged in the horizontal direction of the screen screen, and diffuses the image light in the horizontal direction of the screen screen. To work. A black stripe 8 extending in the vertical direction of the screen is formed on the exit surface of the lenticular lens sheet 7 and absorbs external light incident from the screen exit side. Further, a diffusing material 9 is kneaded into the lenticular lens sheet 7 and functions to diffuse the image light in the horizontal and vertical directions of the screen screen.

  In the embodiment of the transmission screen according to the present invention shown in FIG. 2, a total reflection prism portion 10 is provided on the image generation source side of the Fresnel lens sheet. The total reflection prism unit 10 is provided in a range where the incident angle of the image light projected from the direction of the arrow b to the Fresnel lens sheet 6 is at least approximately 42 degrees or more. The total reflection type prism unit 10 totally refracts incident light by a first refraction phenomenon and totally reflects the light refracted by the refraction surface and emits the light to the image viewing side of the Fresnel lens sheet 6. Including a reflective surface. The light totally reflected by the total reflection surface is at least a first direction substantially perpendicular to the surface of the Fresnel lens sheet 6, and a second direction facing the inner side of the Fresnel lens sheet 6 more than the total reflection angle from the first direction. And emitted in two directions. The refracting surface and / or the total reflection surface of the total reflection type prism unit 10 is composed of at least two or more surfaces, a spherical surface or an aspherical surface, in order to emit light in such two directions. Further, in this embodiment, the refractive prism portion is in a range facing the region where the total reflection prism portion is not provided on the image viewing side of the Fresnel lens sheet 6 (a range where the incident angle is 42 degrees or less). 30 is provided. The refracting prism unit 30 refracts incident light by the second refraction phenomenon and emits light having a predetermined emission angle in the image viewing direction. In this embodiment, the total reflection prism unit 10 cuts a part of the incident light so that a part of the light incident on the total reflection prism unit 10 is not emitted to the image viewing side. The optical element for reducing the transmittance with respect to the incident light of the total reflection type prism unit 10 is included. The total reflection prism portion and the optical element of this embodiment will be described below with reference to FIGS. In the following description, for the sake of convenience, the entire total reflection type prism portion formed on the incident surface of the Fresnel lens sheet is formed on the incident surface total reflection type Fresnel (or the incident-side Fresnel) and the output surface of the Fresnel lens sheet. The entire refraction type prism portion is referred to as an exit surface refraction type Fresnel (or exit side Fresnel).

  First, the optical phenomenon that occurs when the total reflection prism portion is formed over the entire surface of the Fresnel lens sheet incident surface will be described with reference to FIGS. FIG. 3 is a diagram illustrating the transmittance characteristics of the exit-side Fresnel and the entrance-side Fresnel with respect to the incident angle of the light beam on the Fresnel lens sheet 6. In FIG. 3, the incident angle of the light ray to the Fresnel lens sheet is shown on the horizontal axis, and the transmittance of the outgoing side Fresnel and the incoming side Fresnel is shown on the vertical axis. The transmittance of the output-side Fresnel (broken line in FIG. 3) is represented by (1-k), where k is the reflection loss shown on the vertical axis in FIG. As is apparent from FIG. 3, the transmittance of the incident-side Fresnel (solid line in FIG. 3) decreases rapidly when the incident angle of the light beam is less than 42 degrees. Such a phenomenon occurs because stray light is generated by light incident at an incident angle of less than 42 degrees. FIG. 4 shows the generation mechanism of the stray light. FIG. 4 is a ray tracing diagram when light rays are incident on the sheet 11 on which the total reflection type prism portion is formed over the entire surface of the Fresnel lens sheet incident surface at an incident angle of, for example, less than 42 degrees. The light beam A incident obliquely from below is incident from the incident surface 12 of the sheet 11, most of which is totally reflected by the total reflection surface 13 and is emitted from the emission surface 14 of the sheet 11. However, if the light incident angle is less than 42 degrees, a part of the incident light cannot be totally reflected by the total reflection surface 13 but becomes a light beam directed directly to the emission surface 14. The luminous flux is totally reflected by the exit surface 14 and returns to the total reflection Fresnel surface constituted by the incident surface 12 and the total reflection surface 13 again. Since the total reflection Fresnel surface is a triangular prism composed of the incident surface 12 and the total reflection surface 13, these light beams make a U-turn and travel again toward the exit surface 14 of the sheet 11 as shown in the figure. This time, since these light beams are incident on the emission surface 14 at an angle smaller than the total reflection angle, they are emitted from the sheet 11 as stray light C. The stray light C not only lowers the transmission efficiency of the sheet 11 by C / A, but also emits light to the viewer side as a double image, which causes image quality degradation. As described above, when light is incident on the incident-side Fresnel at a angle less than the total reflection angle (for example, less than 42 degrees), stray light is generated as described above. For this reason, as described with reference to FIG. 3, the transmittance of the incident-side Fresnel with respect to light incident at less than the total reflection angle is drastically reduced as compared with the transmittance with respect to light incident at or above that angle.

  Therefore, in this embodiment, the total reflection prism portion is provided only in the region where the light incident angle is large (that is, the total reflection angle (for example, 42 degrees or more)) on the Fresnel lens sheet incident side, and the light incident angle is small (that is, total reflection). The corner (for example, less than 42 degrees) region is a flat portion without providing the total reflection prism portion. On the other hand, an efficient refractive prism portion is provided in a range including the region facing the region where the light incident angle is small (that is, the flat portion) on the Fresnel lens sheet emission side. In this embodiment, the region facing the total reflection prism portion on the Fresnel lens sheet emission side is a flat portion.

  At this time, a boundary portion between the total reflection prism portion and the refraction type prism portion (in the vicinity of a portion where the total reflection type prism portion and the refraction type prism portion overlap or are close to each other in the normal direction of the surface of the Fresnel lens sheet 6 (hereinafter referred to as “the vicinity”) , Simply referred to as “boundary portion”)), the transmittances of the two need to be substantially equal. As shown in FIG. 3, the stray light described above is generated in the incident-side Fresnel portion at the boundary portion (for example, the position where the light incident angle is 40.5 degrees), and the transmittance is rapidly increased in the vicinity of the boundary portion. This is because a decrease occurs. When the transmittance decreases near the boundary, when the image on the screen is observed, the vicinity of the boundary is visually recognized as a black band (a portion where the brightness is lower than the other portions). In addition, the above-mentioned double image is also generated, and the image quality is deteriorated. Therefore, in this embodiment, the transmittance of the incident-side Fresnel is lowered, and the boundary portion is set at a position where the stray light does not occur in the incident-side prism. FIG. 5 is a diagram for explaining this. In FIG. 3, the transmittance of the incident-side Fresnel according to this embodiment (solid line in FIG. 5) is added. The transmittance of the incident-side Fresnel indicated by a solid line in FIG. 3 is indicated by a two-dot chain line in FIG. As shown in FIG. 5, in this embodiment, the transmittance of the incident-side Fresnel is lowered by the amount of the white arrow as compared with that shown in FIG. That is, the transmittance characteristic of the incident-side Fresnel indicated by the solid line and the transmittance characteristic of the emission-side Fresnel indicated by the broken line are crossed at a position where stray light does not occur. Then, the crossing point (42.5 degrees in the embodiment of FIG. 5) is set as the boundary portion. As a result, the transmittances of the incident-side Fresnel (total reflection prism portion) and the emission-side Fresnel (refractive prism portion) are substantially equal to each other at the boundary, and the vicinity of the boundary is visually recognized as a black band. It is suppressed.

  When lowering the transmittance of the incident-side Fresnel, as shown in FIG. 4, the method of generating stray light emitted to the viewer side causes a significant decrease in image quality. Therefore, in this embodiment, a part of the incident light is cut and transmitted to the total reflection prism unit 10 so that a part of the light incident on the total reflection prism unit is not emitted to the image viewing side. An optical element was provided to reduce the rate. A specific example of this optical element is shown in FIG. FIG. 6 shows an inclined surface for guiding, as the optical element, a part of light incident on the total reflection prism unit 10 to be reflected in a direction not emitted to the image viewing side. In this example, 17 and the second reflecting surface 18 are provided. That is, the total reflection type prism unit 10 of the present embodiment includes the two-stage incident surface 15 and the two-stage total reflection surface 16. Most of the light beam D incident from below enters the incident surface 15, is totally reflected by the total reflection surface 16, and is emitted as a light beam E in a first direction substantially perpendicular to the Fresnel lens sheet. On the other hand, a part of the light beam D is incident on the inclined portion 17 provided on the incident surface 15, and the second total reflection surface 18 provided near the root of the total reflection surface 16 from the first direction. Is also totally reflected in the second direction facing inward beyond the total reflection angle of the Fresnel lens sheet. The luminous flux in the second direction is totally reflected by the exit surface 19 of the Fresnel lens sheet 6 because it is directed more inside than the first direction by the total reflection angle of the Fresnel lens sheet. The totally reflected light returns to the total reflection prism unit 10 as shown in FIG. The returned light is not incident on the total reflection surface 16 of the total reflection type prism unit 10 but is incident on the incident surface 15 and the inclined portion 17. The light incident on the inclined portion 17 passes through the inclined portion as it is and is emitted out of the Fresnel lens sheet 6. On the other hand, the light incident on the incident surface 15 is totally reflected by the incident surface 15, passes through the total reflection surface 16, is emitted as the light flux F outside the Fresnel lens sheet 6, and returns to the Fresnel lens sheet 6. It does n’t come. Therefore, according to the present embodiment, it is possible to reduce the transmittance of the Fresnel lens sheet 6 by a predetermined amount without greatly reducing the image quality.

  In FIG. 5, the transmittance of the incident-side Fresnel has been described as being lowered substantially uniformly as a whole. However, depending on the image display device using the Fresnel lens sheet, the brightness may decrease in the peripheral portion. In this case, the transmittance of the incident-side Fresnel is not lowered as a whole as shown in FIG. 5, but the transmittance is increased toward the periphery of the screen (the transmittance is not lowered). An example is shown in FIG.

  In the specific example shown in FIG. 6 described above, a part of the lower side of the light beam incident on the total reflection type prism unit (inner side with respect to the Fresnel center) is used as the root of the total reflection surface of the total reflection type prism unit. The partial light flux is reflected downward (inward with respect to the Fresnel center) by the total reflection surface provided there. Therefore, the entire surface of the total reflection surface of the total reflection type prism portion is used as a normal total reflection surface (total reflection surface for emitting light from the emission surface 16; hereinafter referred to as “effective reflection surface”). I can't. In the specific example of FIG. 6, the range used for the effective reflection surface is 63% of all the total reflection surfaces. When the range used for the effective reflection surface is narrowed, the minimum value of the light incident angle at which light can be emitted substantially perpendicularly to the Fresnel lens sheet as the total reflection Fresnel increases. This relationship is shown in FIG. When the area ratio is 1 (all reflecting surfaces are effective reflecting surfaces), the minimum value of the incident angle of light that can be emitted substantially perpendicular to the Fresnel lens sheet was 42 degrees, whereas the effective reflecting surface 63% It is 57 degrees. In this embodiment, the effective reflection surface is 83%, and the minimum value of the light incident angle is 48 degrees. However, it is difficult to realize the total reflection type prism portion shape below that. Since this minimum angle is the boundary with the output-side Fresnel, the smaller the smaller the angle, the higher the overall transmittance can be set.

  Another specific example of the optical element provided in the total reflection prism unit will be described with reference to FIG. FIG. 9 shows an example in which a light-shielding portion 23 that shields part of the light incident on the total reflection prism portion 20 is provided as the optical element. In other words, in the present embodiment, the total reflection type prism unit 20 includes an incident surface 21, a total reflection surface 22, and a light-shielding unit 23 provided with black paint. A light beam incident from below enters the incident surface 21, but part of the light is shielded by the light shielding unit 23. The light beam incident on the incident surface 21 is totally reflected by the total reflection surface 22 and is emitted in a direction substantially perpendicular to the Fresnel lens sheet. In this embodiment, the amount of light emitted from the incident light beam is reduced by the amount shielded by the light shielding portion 23. Therefore, the transmittance of the Fresnel lens sheet 6 can be adjusted by changing the ratio of the light shielding portion 23. As described above, it is possible to reduce the transmittance of the incident-side Fresnel substantially uniformly, or to increase the transmittance toward the periphery (do not lower the transmittance). Since the light-shielding part 23 in this embodiment is provided at the tip of the total reflection type prism part, it is possible to form the light-shielding part 23 by black coating with normal screen printing or hot stamping.

1 is a cross-sectional perspective view illustrating an example of an image display device to which the present invention is applied. The figure which shows one Example of the transmissive screen 3 which concerns on this invention. The figure which shows the transmittance | permeability of an output side Fresnel and an incident side Fresnel. The figure which shows the generation | occurrence | production mechanism of a stray light. The figure which showed the transmittance | permeability of the incident side Fresnel by the Example of this invention. The figure which shows one specific example of the optical element provided in the total reflection type prism part. The figure which shows the other example of the transmittance | permeability of the incident side Fresnel by the Example of this invention. It is a figure showing the relationship between the ratio of the effective reflective surface with respect to the total reflection surface of a total reflection type prism part, and a light ray incident angle. The figure which shows the other specific example of the optical element provided in the total reflection type prism part. The figure which showed the relationship between the light ray incident angle to the screen of a general output surface Fresnel lens, and reflection loss.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image generation source, 2 ... Projection lens, 3 ... Transmission type screen, 4 ... Reflection mirror, 5 ... Case, 6 ... Fresnel lens sheet, 7 ... Diffuse sheet, 10 ... Total reflection type prism part, 15 ... Stepped , 16... Two-stage total reflection surface, 17... Inclined portion, 18... Second total reflection surface, 23.

Claims (21)

On the screen where the light from the image source is projected,
A Fresnel lens sheet having a total reflection prism portion formed on the image generation source side and a refraction prism portion formed on the image viewing side;
A diffusion sheet disposed on the image viewing side of the Fresnel lens sheet and diffusing video light at least in the horizontal direction of the screen,
The total reflection prism portion is formed in a region where the light is incident at a predetermined incident angle or more on the image generation source side of the Fresnel lens sheet, and an incident surface on which the light is incident, and the incident surface A total reflection surface that reflects the incident light from the light and emits it to the image viewing side,
The refractive prism portion is formed in a region facing the region where the total reflection prism portion is not formed on the image viewing side of the Fresnel lens sheet, and refracts the light toward the image viewing side. Including the exiting refractive surface,
The total reflection prism unit includes an element for cutting a part of the incident light so that a part of the light incident on the total reflection prism unit is not emitted to the image viewing side. And screen.   The element of the total reflection prism unit is a reflection surface for reflecting a part of light incident on the total reflection prism unit in a direction not emitted to the image viewing side. The screen according to 1.   2. The screen according to claim 1, wherein the element of the total reflection type prism unit is a light blocking unit that blocks a part of light incident on the total reflection type prism unit. On the screen where the light from the image source is projected,
A Fresnel lens sheet having a total reflection prism portion formed on the image generation source side and a refraction prism portion formed on the image viewing side;
A diffusion sheet disposed on the image viewing side of the Fresnel lens sheet and diffusing video light at least in the horizontal direction of the screen,
The total reflection prism portion is formed in a region where the light is incident at a predetermined incident angle or more on the image generation source side of the Fresnel lens sheet, and an incident surface on which the light is incident, and the incident surface A total reflection surface that reflects the incident light from the light and emits it to the image viewing side,
The refractive prism portion is formed in a region facing the region where the total reflection prism portion is not formed on the image viewing side of the Fresnel lens sheet, and refracts the light toward the image viewing side. Including the exiting refractive surface,
The screen according to claim 1, wherein the total reflection prism unit includes an element that reduces a transmittance of light incident on the total reflection prism unit.   The decrease in transmittance due to the element of the total reflection prism portion provided at a position where the incident angle is large is lower than the decrease in transmittance due to the element of the total reflection prism portion provided at a position where the incident angle is small. The screen according to claim 4, wherein the screen is large.   The total reflection type prism unit causes the incident light beam to be directed inward at least in a direction substantially perpendicular to the Fresnel lens sheet and beyond the total reflection angle of the Fresnel lens sheet by the total reflection phenomenon after the first refraction phenomenon. 5. The method according to claim 4, further comprising at least two or more surfaces, an incident surface composed of a spherical surface or an aspherical surface, and a total reflection surface, each of which provides an incident surface exit angle in two or more directions. screen.   5. The screen according to claim 4, wherein the element of the total reflection type prism unit is a light blocking unit that blocks a part of light incident on the total reflection type prism unit. On the screen where the light from the image source is projected,
A Fresnel lens sheet having a total reflection prism portion formed on the image generation source side and a refraction prism portion formed on the image viewing side;
A diffusion sheet disposed on the image viewing side of the Fresnel lens sheet and diffusing video light at least in the horizontal direction of the screen,
The total reflection prism portion is formed in a region where the light is incident at a predetermined incident angle or more on the image generation source side of the Fresnel lens sheet, and an incident surface on which the light is incident, and the incident surface A total reflection surface that reflects the incident light from the light and emits it to the image viewing side,
The refractive prism portion is formed in a region facing the region where the total reflection prism portion is not formed on the image viewing side of the Fresnel lens sheet, and refracts the light toward the image viewing side. Including the exiting refractive surface,
In the vicinity of the boundary between the total reflection prism portion and the refractive prism portion, the transmittance of the total reflection prism portion and the refractive prism portion is substantially equal. In an image display device,
An image generation source, an optical component that magnifies and projects an image of the image generation source, and a transmissive screen that projects a projection image projected from the optical component,
The transmissive screen includes at least a Fresnel lens sheet disposed on the image generation source side, and a diffusion sheet disposed on the image viewing side and diffusing video light at least in the horizontal direction of the screen,
The Fresnel lens sheet includes a total reflection prism portion formed on the image generation source side, and a refraction prism portion formed on the image viewing side,
The total reflection prism portion is formed in a region where the light is incident at a predetermined incident angle or more on the image generation source side of the Fresnel lens sheet, and an incident surface on which the light is incident, and the incident surface A total reflection surface that reflects the incident light from the light and emits it to the image viewing side,
The refractive prism portion is formed in a region facing the region where the total reflection prism portion is not formed on the image viewing side of the Fresnel lens sheet, and refracts the light toward the image viewing side. Including the exiting refractive surface,
The total reflection prism unit includes an element for cutting a part of the incident light so that a part of the light incident on the total reflection prism unit is not emitted to the image viewing side. An image display device. In an image display device,
An image generation source, an optical component that magnifies and projects an image of the image generation source, and a transmissive screen that projects a projection image projected from the optical component,
The transmissive screen includes at least a Fresnel lens sheet disposed on the image generation source side, and a diffusion sheet disposed on the image viewing side and diffusing video light at least in the horizontal direction of the screen,
The Fresnel lens sheet includes a total reflection prism portion formed on the image generation source side, and a refraction prism portion formed on the image viewing side,
The total reflection prism portion is formed in a region where the light is incident at a predetermined incident angle or more on the image generation source side of the Fresnel lens sheet, and an incident surface on which the light is incident, and the incident surface A total reflection surface that reflects the incident light from the light and emits it to the image viewing side,
The refractive prism portion is formed in a region facing the region where the total reflection prism portion is not formed on the image viewing side of the Fresnel lens sheet, and refracts the light toward the image viewing side. Including the exiting refractive surface,
The image display apparatus according to claim 1, wherein the total reflection prism unit includes an element that reduces a transmittance for light incident on the total reflection prism unit.   The decrease in transmittance due to the element of the total reflection prism portion provided at a position where the incident angle is large is lower than the decrease in transmittance due to the element of the total reflection prism portion provided at a position where the incident angle is small. The image display device according to claim 10, wherein the image display device is large.   The total reflection type prism unit causes the incident light beam to be directed inward at least in a direction substantially perpendicular to the Fresnel lens sheet and beyond the total reflection angle of the Fresnel lens sheet by the total reflection phenomenon after the first refraction phenomenon. 11. The light emitting device according to claim 10, further comprising at least two or more surfaces, an incident surface made up of a spherical surface or an aspherical surface, and a total reflection surface, each of which provides an incident surface exit angle in two or more directions. Image display device.   The image display device according to claim 10, wherein the element of the total reflection type prism unit is a light blocking unit that blocks a part of light incident on the total reflection type prism unit. An image generation source, an optical component that magnifies and projects an image of the image generation source, and a transmissive screen that projects a projection image projected from the optical component,
The transmissive screen includes at least a Fresnel lens sheet disposed on the image generation source side, and a diffusion sheet disposed on the image viewing side and diffusing video light at least in the horizontal direction of the screen,
The Fresnel lens sheet includes a total reflection type prism portion formed on the image generation source side and a refraction type prism portion formed on the image viewing side, and the total reflection type prism portion is formed of the Fresnel lens sheet. It is formed on the image generation source side in the region where the light is incident at a predetermined incident angle or more,
The refractive prism portion is formed in a region facing the region where the total reflection prism portion is not formed on the image viewing side of the Fresnel lens sheet, and refracts the light toward the image viewing side. Including the exiting refractive surface,
An image display device characterized in that, in the vicinity of a boundary portion between the total reflection prism unit and the refraction type prism unit, the transmittances of the total reflection type prism unit and the refraction type prism unit are substantially equal. In a Fresnel lens sheet used for a transmissive screen on which light from an image source is projected,
A total reflection type prism portion formed on the image generation source side, and a refraction type prism portion formed on the image viewing side,
The total reflection prism portion is formed in a region where the light is incident at a predetermined incident angle or more on the image generation source side of the Fresnel lens sheet, and an incident surface on which the light is incident, and the incident surface A total reflection surface that reflects the incident light from the light and emits it to the image viewing side,
The refractive prism portion is formed in a region facing the region where the total reflection prism portion is not formed on the image viewing side of the Fresnel lens sheet, and refracts the light toward the image viewing side. Including the exiting refractive surface,
The total reflection prism unit includes an element for cutting a part of the incident light so that a part of the light incident on the total reflection prism unit is not emitted to the image viewing side. Fresnel lens sheet.   The element of the total reflection prism unit is a reflection surface for reflecting a part of light incident on the total reflection prism unit in a direction not emitted to the image viewing side. 15. The Fresnel lens sheet according to 15.   The Fresnel lens sheet according to claim 15, wherein the element of the total reflection prism unit is a light blocking unit that blocks a part of light incident on the total reflection prism unit. In a Fresnel lens sheet used for a transmissive screen on which light from an image source is projected,
A total reflection type prism portion formed on the image generation source side, and a refraction type prism portion formed on the image viewing side,
The total reflection prism portion is formed in a region where the light is incident at a predetermined incident angle or more on the image generation source side of the Fresnel lens sheet, and an incident surface on which the light is incident, and the incident surface A total reflection surface that reflects the incident light from the light and emits it to the image viewing side,
The refractive prism portion is formed in a region facing the region where the total reflection prism portion is not formed on the image viewing side of the Fresnel lens sheet, and refracts the light toward the image viewing side. Including the exiting refractive surface,
The Fresnel lens sheet, wherein the total reflection prism portion includes an element that reduces a transmittance for light incident on the total reflection prism portion. In a Fresnel lens sheet used for a transmissive screen on which light from an image source is projected,
A total reflection type prism portion formed on the image generation source side, and a refraction type prism portion formed on the image viewing side,
The total reflection type prism unit causes the incident light rays to be at least substantially perpendicular to the Fresnel lens sheet and more than the total reflection angle of the Fresnel lens sheet by the total reflection phenomenon after the first refraction phenomenon. A Fresnel lens sheet comprising an incident surface made up of at least two surfaces, a spherical surface or an aspherical surface, and a total reflection surface, each of which provides an incident surface exit angle in two or more directions with respect to a direction. In a Fresnel lens sheet used for a transmissive screen on which light from an image source is projected,
A total reflection type prism portion formed on the image generation source side, and a refraction type prism portion formed on the image viewing side,
The total reflection prism unit includes an incident surface on which light is incident, a total reflection surface that reflects the light incident on the incident surface, and a light shield that blocks a part of the light incident on the total reflection prism unit. And a Fresnel lens sheet. In a Fresnel lens sheet used for a transmissive screen on which light from an image source is projected,
A total reflection prism portion formed on the image generation source side, and a refraction type prism portion formed on the image viewing side, and in the vicinity of a boundary portion between the total reflection prism portion and the refraction type prism portion A Fresnel lens sheet characterized in that the transmittance of the total reflection type prism part and the refractive type prism part are substantially equal.

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