JP2008039988A - Optical member for transmission type screen and display device equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical member for a transmission type screen where a luminance difference due to stray light is effectively prevented, and a display device. <P>SOLUTION: Provided is the optical member for the transmission type screen equipped with an optical element (A) totally reflecting at least a part of light from a light source and an optical element (B) refracting and transmitting the light from the light source, and characterized by forming a transmitted light attenuating area in both of an area through which light made incident on the optical element (A) passes and an area through which light made incident on the optical element (B) passes, and attenuating the stray light by the transmitted light attenuating areas, thereby reducing irregular brightness of emitted light on the transmission type screen. Then, the display device is equipped with the optical member for the transmission type screen. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical member for a transmissive screen and a display device. More specifically, the present invention relates to an optical member for a transmissive screen suitable as a component of a rear projection type projection system such as a projection TV (hereinafter referred to as “PTV”), and more specifically, at least a part of image light. An optical member having both a lens group that totally reflects light and a prism group that refracts image light, and relates to an optical member for a transmission type screen in which unevenness in brightness is suppressed, and a display device including the optical member. is there.

  In recent years, a single light source PTV using a liquid crystal display (LCD) or a digital micro-mirror device (DMD) has started to appear on the market in place of a projection TV using three tubes of a conventional CRT. The single light source PTV is smaller in light source than the three-tube PTV, and the set size can be reduced.

  In general, in a three-tube type PTV, it is very difficult to shorten the projection distance due to color unevenness caused by different incident angles of light source light on the screen. On the other hand, the single light source PTV does not have this problem, and in order to further reduce the set size, the projection distance is greatly shortened.

  In order to cope with such shortening of the projection distance, it is necessary to shorten the focal length of the Fresnel lens. However, as the focal length is shortened, the lens angle increases at the outer periphery of the screen, resulting in large reflection loss and sufficient peripheral brightness. There is a problem that the outer peripheral portion becomes dark.

  One solution to this problem is to use a total reflection Fresnel lens. However, this method is very effective in reducing the reflection loss at the outer peripheral portion where the incident light angle to the screen is large, but total reflection cannot be caused in the portion where the incident light angle is small, and the light condensing performance is reduced. It is difficult to obtain.

  For this reason, considering the advantages of the refractive Fresnel lens and the total reflection lens, a compound type lens using a refractive Fresnel lens at a small incident light angle and a total reflection lens at a large incident light angle is considered. It has been. However, in such a case, since the generation state and emission state of stray light are different between the refraction part and the total reflection part, the refraction part and the total reflection part are observed when observed from a direction different from the main emission direction of the image light such as an oblique direction. As a result, it was found that a clear luminance difference was generated, which was confirmed as uneven brightness.

The present invention has been made to solve such problems.
Its purpose is a transmissive screen that does not feel uneven brightness due to stray light even when viewed from a direction different from the main emission direction of image light, using a refraction and total reflection composite lens that provides good brightness uniformity It is to provide an optical member for use.
In order to solve the above-described problems, a transmissive screen optical member according to a first aspect of the present invention includes an optical element [A] that totally reflects at least part of light from a light source, and refracting and transmitting light from the light source. An optical element [B] to form a transmitted light attenuation region in both a region through which the light incident on the optical element [A] passes and a region through which the light incident on the optical element [B] passes. It is characterized by that.

  Such an optical member for a transmissive screen according to the present invention preferably comprises the optical element [A] comprising a lens group and / or a prism group that totally reflects at least part of light from the light source, Preferably, it may be composed of a prism group in which a plurality of unit prisms are arranged.

  In such a transmissive screen optical member according to the present invention, preferably, the optical element [B] can be composed of a lens group and / or a prism group that refracts and transmits light from a light source. .

  Such an optical member for a transmissive screen according to the present invention is preferably formed with the optical element [B] at the center thereof on the basis of the center of a concentric circle, and outside the peripheral edge of the optical element [B]. The optical element [A] may be formed.

  In such a transmissive screen optical member according to the present invention, preferably, the transmitted light control region is colored, and the light transmittance in the visible light region is 50 to 50 of the transmittance of the non-colored one. It can be 98%.

  In such an optical member for a transmission type screen according to the present invention, preferably, either one or both of the optical element [A] and the optical element [B] is molded on a substrate with an electron beam curable resin. can do.

  In such a transmissive screen optical member according to the present invention, preferably, the transmitted light attenuation region may be formed on the substrate.

  In such an optical member for a transmission type screen according to the present invention, preferably, the base material is made of a resin having a hygroscopicity lower than that of an acrylic resin.

  In such a transmissive screen optical member according to the present invention, preferably, the transmitted light attenuation region is formed inside one or both of the optical element [A] and the optical element [B]. Can be.

  Such an optical member for a transmissive screen according to the present invention is preferably such that the optical element [A] and the optical element [B] are formed on the same substrate.

  In such a transmissive screen according to the present invention, preferably, the optical element [A] and the optical element [B] may be formed on different substrates.

  Such an optical member for a transmissive screen according to the present invention is preferably configured such that the transmissive screen is held while being stretched.

  Another transmissive screen optical member according to the present invention is characterized in that a diffusion sheet for diffusing the light emitted from any one of the transmissive screen optical members is further provided. Is.

  A display device according to the present invention comprises any one of the above-described optical members for a transmissive screen.

  In the transmissive screen optical member according to the present invention, the optical element [A] that totally reflects at least a part of the light from the light source is disposed in the portion having the large incident light angle, and the light source is disposed in the portion having the small incident light angle. Since the optical element [B] that refracts and transmits the light is disposed and the projection distance is short, the display device can be miniaturized. Usually, in the case of a transmissive screen optical member in which a plurality of optical elements having different stray light generation states and emission states are arranged, there is a difference in luminance particularly when observed from a direction different from the main emission direction of image light such as an oblique direction. However, in the transmissive screen optical member according to the present invention, the stray light is attenuated by the transmitted light attenuation region, so that the occurrence of the luminance difference is effectively prevented.

  An optical member for a transmissive screen according to the present invention includes an optical element [A] that totally reflects at least a part of light from a light source, and an optical element [B] that refracts and transmits light from the light source. A transmitted light attenuation region is formed in both the region through which the light incident on [A] passes and the region through which the light incident on the optical element [B] passes. .

  Here, the optical element [A] and the optical element [B] are preferably composed of a lens group and / or a prism group, and particularly preferably composed of a prism group in which a plurality of unit prisms are arranged. be able to.

  In the transmission screen optical member 1 shown in FIGS. 2A to 2C according to the present invention, the optical element [B] 3 is disposed in the center, while the optical element [A] 2 is the optical element. [B] It is arrange | positioned at the peripheral part 3 outer side. That is, an optical element [A] (for example, preferably a total reflection prism group) that totally reflects the light from the light source is disposed in a portion where the incident light angle of the light from the light source L is large, and the light from the light source is incident. An optical element [B] that refracts and transmits light from the light source is disposed in a portion where the light angle is small.

  The optical element [A] and the optical element [B] can be formed on separate sheets as shown in FIG. 2 (a), or one sheet as shown in FIG. 2 (b). It can also be formed on both sides of the sheet, or it can be formed on the same surface of one sheet as shown in FIG. The optical element [A] is usually formed on the light source side of the sheet, that is, on the light incident side of the sheet.

  In such a transmission screen optical member according to the present invention, as shown in FIG. 3 which is a perspective view of the transmission screen optical member 1 of FIG. The optical element [B] is formed at the center with respect to the center O of a concentric circle formed by connecting the points (or points on the screen where the incident light angles of the image light from the light source are equal). The optical element [A] can be formed by arranging a prism group in which unit prisms are arranged concentrically outside the peripheral edge of the element [B]. The concentric circle is usually a perfect circle, but may be an ellipse in some cases.

  In the transmissive screen optical member according to the present invention, the transmissive screen has both a region through which the light incident on the optical element [A] passes and a region through which the light incident on the optical element [B] passes. By forming a transmitted light attenuation region and attenuating stray light by the transmitted light attenuation region, uneven brightness of the light emitted from the transmission type screen is reduced.

  Here, the stray light means light other than light necessary for forming an image and adversely affecting the image. If such stray light is mixed in the outgoing light, it can cause double images (ghosts) and a decrease in contrast.

  In particular, in the case of a transmission type screen in which a plurality of types of optical elements having different surface shapes are formed, such as an optical member for a transmission type screen according to the present invention, luminance unevenness in emitted light, particularly when observed from an oblique direction, A clear luminance difference occurs between the optical element [A] and the optical element [B], which is confirmed as uneven brightness.

  When this problem was examined, the optical element [A] and the optical element [B] have different stray light generation states and light emission states between the optical elements, and the presence of the stray light. Has a great influence on the luminance unevenness, and that these stray lights are different in direction from the main emitted light connecting the target image and are transmitted through the transmission screen in an oblique direction.

  In the present invention, the main emitted light is also attenuated by the transmitted light control region, but the attenuation of the stray light passing through the longer optical path in the transmissive screen is larger, and as a result, the ratio of the stray light to the main emitted light is increased. And the various problems caused by the stray light are reduced.

  This transmitted light control region is preferably colored, and has a light transmittance in the visible light region of 50 to 98% of the non-colored one, preferably 85 to 95% of the non-colored one. be able to.

  A method for setting the light transmittance within the above range is arbitrary. For example, in the present invention, a colorant, a pigment or a dye can be used. Two or more of these can be used in combination. These blending amounts can be determined in consideration of light transmittance. The thickness of the transmitted light attenuation region can be determined within an appropriate range in consideration of the attenuation state of stray light and main emitted light, the effect of reducing brightness unevenness, the size of the screen, the manufacturing cost, and the like.

  Note that the light transmittance of the transmitted light attenuation region does not always have to be constant in all the regions, and may be partially different. For example, the light transmittance of the transmitted light control region formed in the region through which the light incident on the optical element [A] passes is set to be the light of the transmitted light control region formed in the region through which the light incident on the optical element [B] passes. It can be made higher (or lower) than the transmittance.

  Also, the light transmittance can be partially changed in the transmitted light attenuation region formed in the region through which the light incident on the optical element [A] passes. Similarly, the light transmittance can be partially changed in the transmitted light damping region formed in the region through which the light incident on the optical element [B] passes.

  The transmitted light attenuation region is a region through which light passes until the light enters the transmissive screen on which the optical element [A] and the optical element [B] according to the present invention are formed and is emitted from the screen. At least part of the light path, that is, at least part of the light path in the region that becomes the light path in the transmission screen. Therefore, the transmitted light attenuation region is formed outside the optical element [A] and / or the optical element [B] as being independent of the optical element [A] and / or the optical element [B], for example. It can also be formed inside the optical element [A] and / or the optical element [B].

  As one specific example of the transmitted light attenuation region formed outside the optical element, either one or both of the optical element [A] and the optical element [B] are shaped on a substrate. It can be illustrated that the transmitted light attenuation region is formed on this substrate.

  FIG. 1A shows a cross section of a transmissive screen in which the optical element [A] 2 is shaped on the substrate 5 and the transmitted light attenuation region 4 is formed on the substrate 5. In this figure, the light L1 from the light source is incident on the optical element [A] 2 of the transmission screen according to the present invention, totally reflected, and then emitted from the main outgoing light L2 and the optical element [A]. 2 shows the optical path of stray light L3 that enters 2 and exits without being totally reflected. Here, since the stray light L3 has a longer optical path in the transmitted light control region 4 than the main emission light L2, the stray light L3 is further attenuated.

  As said base material, various materials suitable as optical members for transmission screens, such as glass and resin, can be used. In general, acrylic resin has been used as a resin material for transmission screens due to its transparency. However, moisture absorption is large, and warpage changes due to the difference in dimensions between the front and back of the screen due to moisture absorption, so that light enters the screen at a design angle. In some cases, desired optical characteristics may not be obtained. From this viewpoint, in the present invention, those made of a resin having low hygroscopicity are preferable. By reducing the hygroscopicity, the warped state of the screen does not change, and light enters at an angle as designed, and desired characteristics can be obtained. Examples of the resin having lower hygroscopicity than the acrylic resin include acrylic-styrene copolymer resin (MS), polystyrene, polycarbonate, polypropylene (PP), and polyethylene terephthalate (PET). The resin base material can also contain fine particles having light diffusibility. Examples of such fine particles include resin beads made of acrylic resin, cross-linked acrylic-styrene copolymer resin, cross-linked styrene, glass, silica, alumina, and the like. The thickness of the resin substrate is usually 0.08 to 5.0 mm, preferably 0.15 to 2.0 mm. If the necessary conditions for the substrate are satisfied, a thinner thickness is advantageous in terms of product cost.

  As a preferable specific example of the electron beam curable resin when one or both of the optical element [A] or the optical element [B] according to the present invention is formed from an electron beam curable resin, for example, urethane resin Or an epoxy-type resin etc. can be illustrated.

  On the other hand, as a specific example of the case where the transmitted light control region is formed inside the optical element, the optical element [A] and / or the optical element [B] itself is colored and the optical element [ A) and / or the entire optical element [B] itself may be a transmitted light attenuation region.

  In FIG. 1 (b), the optical element [A] 2 is shaped on the substrate 5 and the transmitted light control region 4 is formed on the optical element [A] 2. It is shown. In this figure, the light L1 from the light source is incident on the optical element [A] 2 of the optical member for transmission type screen according to the present invention, and after being totally reflected, the optical path of the main outgoing light L2 emitted and the optical element [A] The optical path of the stray light L4 reflected without being incident on 2 is shown. Here, the stray light L4 is attenuated more because the stray light L4 has a longer optical path in the transmitted light attenuation region 4 than the main outgoing light L2.

  The optical member for a transmission screen according to the present invention as described above can be held while being stretched. The transmissive screen optical member according to the present invention, which is held while being stretched, can be effectively prevented from being affected by expansion and contraction due to heat and moisture absorption, wrinkles, etc., especially when the substrate thickness is thin. The state is maintained, and problems with optical characteristics and appearance due to wrinkles can be prevented.

  The transmission screen optical member according to the present invention may have other optical elements or configurations as needed in addition to the above-described configuration. For example, a lens sheet or a light diffusing element for diffusing light emitted from the optical member for a transmission type screen may be further provided. The lens sheet or the light diffusing element means both an object that diffuses light in the horizontal direction and an object that diffuses light in the vertical direction. Further, the transmission screen according to the present invention may have other configurations applicable to this type of transmission screen, for example, a hard coat layer, an antistatic layer, a moisture-proof layer, a supporting substrate, etc. in addition to a lenticular lens. Can be provided.

  The thickness of the transmissive screen optical member according to the present invention is preferably 0.5 to 5.0 mm, particularly preferably 1.0 to 2.0 mm.

  4 to 6 and FIGS. 8 to 13 show some preferred specific examples of the optical member for a transmissive screen according to the present invention.

  Among these, FIG. 8 shows an example in which a lenticular lens 6 a is added as a light diffusing element to a base material on which the optical element [A] 2 is formed, and a light diffusing plate is further provided as another light diffusing element 6. FIG. 9 shows an example in which a lenticular lens 6a is added as a light diffusing element to the substrate on which the optical element [A] 2 is formed, and another light diffusing element 6 is further provided on the optical element [B] 3 side. . FIG. 10 shows an example in which a lenticular lens is provided as a light diffusing element 6 on a separate sheet from the optical elements [A] and [B]. FIG. 11 shows an example in which an optical sheet using total reflection as the light diffusing element 6 is provided on a sheet different from the optical elements [A] and [B]. 12 and 13 show an example in which a lenticular lens having a light absorbing portion on the observer side is used as the light diffusing element 6.

<Example 1>
PTV: Size: 50 inches W (screen outer size: about 650 mm × 1130 mm), a DLP (Digital Light Processing) projector light source with a projection distance of 550 mm is used.
LL: A single-sided lenticular lens sheet having a lenticular lens group with a lens pitch of 0.143 mm on the light incident surface.
FL (B-1): A Fresnel lens group having a refractive Fresnel lens group with a focal length of 550 mm and a lens pitch of 0.112 mm within a radius of 343.4 mm from the center of the screen on the light exit surface side, and no lens within a radius of 343.4 mm or more. Lens sheet. The structure of this Fresnel lens sheet is a 2.5 mm colored transparent acrylic resin sheet with a dye added to the resin and 75% transmittance in the visible light region.
FL (A-1): A total reflection Fresnel lens group having a focal length of 550 mm and a lens pitch of 0.112 mm is within a radius of 343.4 mm from the screen center on the light incident surface side, and the lens is within a radius of 343.4 mm. No Fresnel lens sheet. The structure of this Fresnel lens sheet is based on a 1.5mm colored transparent acrylic resin sheet with a dye added to the resin and a visible light transmittance of 75%, and the lens shape is shaped by an electron beam curable resin.

  As shown in FIG. 4, from the light source side, the FL (A-1), FL (B-1), and LL were stacked in this order to produce a transmissive screen optical member. When this optical member for a transmissive screen is set on a PTV, even if the screen is observed from an oblique direction with respect to the screen, brightness unevenness with a radius of 343.4 mm as a boundary does not occur, and uniform brightness is obtained. An image with was obtained.

<Example 2>
PTV: Size: 50 inches W (screen external size: about 650 mm × 1130 mm), LCD (Liquid Crystal Display) projector light source with a projection distance of 550 mm is used.
LL: A single-sided lenticular lens sheet having a lenticular lens group with a lens pitch of 0.143 mm on the light incident surface.
FL: Refractive Fresnel lens group B with a focal length of 550 mm and a lens pitch of 0.112 mm is within a radius of 343.4 mm from the center of the screen on the light exit surface side, and there is no lens within the range of the light exit surface side radius of 343.4 mm or more. A Fresnel lens having a total reflection Fresnel lens group A having a distance of 550 mm and a lens pitch of 0.112 mm within a radius of 343.4 mm from the center of the screen on the light incident surface side and having no lens within a radius of 343.4 mm on the light incident surface side Sheet. The Fresnel lens sheet has a structure in which a lens group A is provided on the light incident surface side of a 1.0 mm colored transparent polycarbonate sheet in which a dye is added to the resin and the transmittance in the visible light region is 70%, and the lens group B is provided on the light exit surface side. The lens shape is shaped by electron beam curable resin.

  As shown in FIG. 5, from the light source side, the FL and LL were stacked in this order to produce a transmissive screen optical member. When this optical member for a transmissive screen is set on a PTV, even if the screen is observed from an oblique direction with respect to the screen, brightness unevenness with a radius of 343.4 mm as a boundary does not occur, and uniform brightness is obtained. An image with was obtained. In addition, even when left in a hot and humid environment, the Fresnel lens did not move and a good image was obtained.

<Example 3>
PTV: Size: 50 inches W (screen external size: about 650 mm × 1130 mm), using an LCD (Digital Light Processing) projector light source with a projection distance of 550 mm. A structure in which the four sides of the film-like screen are sandwiched independently by a jig, and the jig is stretched from the frame with a spring.
LL: A single-sided lenticular lens sheet having a lenticular lens group with a lens pitch of 0.143 mm on the light incident surface.
FL (B-4): A Fresnel lens group having a focal length of 550 mm and a lens pitch of 0.112 mm within a radius of 343.4 mm from the center of the screen on the light exit surface side, and having no lens within a radius of 343.4 mm or more. Lens sheet. The structure of this Fresnel lens sheet is that the lens shape is molded with an electron beam curable resin on a 0.188 mm colored transparent PET film with a visible light transmittance of 65%.
FL (A-4): Total reflection Fresnel lens group having a focal length of 550 mm and a lens pitch of 0.112 mm is within a radius of 343.4 mm from the center of the screen on the light incident surface side, and has a lens within a radius of 343.4 mm. No Fresnel lens sheet. The structure of this Fresnel lens sheet is made of 0.188 mm transparent PET with an electron beam curable resin.

  As shown in FIG. 6, from the light source side, the FL (A-4), FL (B-4), and LL were stacked in this order to produce a transmissive screen optical member. When this optical member for a transmissive screen is set on a PTV, even if the screen is observed from an oblique direction with respect to the screen, brightness unevenness with a radius of 343.4 mm as a boundary does not occur, and uniform brightness is obtained. An image with was obtained. In addition, the manufacturing cost could be reduced, and even when left in a hot and humid environment, the Fresnel lens did not move and a good image was obtained.

<Comparative Example 1>
PTV: An LCD projector light source with a size of 50 ″ W and a projection distance of 550 mm is used.
LL: A single-sided lenticular lens sheet having a lenticular lens group with a lens pitch of 0.143 mm on the light incident surface.
FL (B-5): a Fresnel lens group having a focal length of 550 mm and a lens pitch of 0.112 mm within a radius of 343.4 mm from the center of the screen on the light exit surface side, and no lens within a radius of 343.4 mm or more Lens sheet.
The structure of the Fresnel lens sheet is a 1.5 mm transparent acrylic resin sheet that is shaped by an electron beam curable resin.

  FL (A-5): A total reflection Fresnel lens group having a focal length of 550 mm and a lens pitch of 0.112 mm is within a radius of 343.4 mm from the center of the screen on the light incident surface side, and the lens is within a radius of 343.4 mm. No Fresnel lens sheet. The structure of this Fresnel lens sheet is a lens with a 1.5 mm transparent acrylic resin sheet that is shaped by an electron beam curable resin.

  As shown in FIG. 7, from the light source side, the FL (A-5), FL (B-5), and LL are stacked in this order to form an optical member for a transmissive screen and set on the PTV. Observation from an oblique direction revealed brightness unevenness with a radius of 343.4 mm as a boundary, and an image with a poor brightness balance was obtained.

1A and 1B are sectional views of an optical member for a transmission screen according to the present invention. 2A to 2C are sectional views of an optical member for a transmission screen according to the present invention. The perspective view which shows the outline | summary of the optical member for transmissive screens by this invention Sectional drawing of the optical member for transmissive | pervious screens by this invention of Example 1 Sectional drawing of the optical member for transmissive | pervious screens by this invention of Example 2 Sectional drawing of the optical member for transmissive | pervious screens by this invention of Example 3 Sectional drawing which shows the optical member for transmissive screens of the comparative example 1 Sectional drawing of the other specific example of the optical member for transmissive screens by this invention Sectional drawing of the other specific example of the optical member for transmissive screens by this invention Sectional drawing of the other specific example of the optical member for transmissive screens by this invention Sectional drawing of the other specific example of the optical member for transmissive screens by this invention Sectional drawing of the other specific example of the optical member for transmissive screens by this invention Sectional drawing of the other specific example of the optical member for transmissive screens by this invention

Explanation of symbols

1 Optical member for transmission screen 2 Optical element [A]
3 Optical elements [B]
4 Transmitted light control region 5 Resin substrate 6 Light diffusing element L Light source L1 Light from light source L2 Main outgoing light L3 Stray light O Concentric center

Claims (14)

  An optical element [A] that totally reflects at least part of light from the light source, and an optical element [B] that refracts and transmits light from the light source, and a region through which light incident on the optical element [A] passes. An optical member for a transmission type screen, wherein a transmitted light attenuation region is formed in both the region through which the light incident on the optical element [B] passes.   2. The optical member for a transmissive screen according to claim 1, wherein the optical element [A] is a lens group and / or a prism group, preferably a prism group in which a plurality of unit prisms are arranged. .   The optical member for transmission type screens according to claim 1 or 2, wherein said optical element [B] consists of a lens group and / or a prism group.   The optical element [B] is formed at the center of the center of the concentric circle, and the optical element [A] is formed outside the peripheral edge of the optical element [B]. The optical member for transmission type screens of any one of -3.   The said transmitted light attenuation | damping area | region is colored, The transmittance | permeability of the light in a visible light area | region is a thing of 50 to 98% of the transmittance | permeability of a non-colored thing, The any one of Claims 1-4. The optical member for transmissive screens described in 1.   Either one or both of the optical element [A] and the optical element [B] are made of an electron beam curable resin shaped on a substrate. Item 4. An optical member for a transmissive screen according to Item.   The optical member for transmissive screen according to claim 6, wherein the transmitted light attenuation region is formed on the base material.   The optical member for transmission type screens according to claim 6 or 7 in which said base material consists of resin whose hygroscopicity is lower than acrylic resin.   9. The transmitted light attenuation region according to claim 1, wherein the transmitted light attenuation region is formed inside one or both of the optical element [A] and the optical element [B]. An optical member for a transmissive screen.   The optical member for transmissive screen according to any one of claims 6 to 9, wherein the optical element [A] and the optical element [B] are formed on the same base material.   The optical member for transmissive screen according to any one of claims 6 to 9, wherein the optical element [A] and the optical element [B] are formed on different substrates.   The optical member for a transmissive screen according to any one of claims 1 to 11, wherein the transmissive screen is held while being stretched.   13. An optical member for a transmission type screen, further comprising a light diffusing element for diffusing light emitted from the optical member for a transmission type screen according to any one of claims 1 to 12. .   A display device comprising the optical member for a transmission screen according to any one of claims 1 to 13.

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