JP2006349962A - Fresnel base sheet, fresnel lens sheet, transmission type screen, and rear projection type display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a Fresnel base sheet capable of reducing uneven brightness and irregular color caused by polarization characteristics of video light and double refraction of a Fresnel base sheet, to provide a Fresnel lens sheet using the Fresnel base sheet, and to provide a transmission type screen and a rear projection type display apparatus. <P>SOLUTION: By using a member satisfying an expression of π-π/2≤R≤π+π/2, provided that the double refraction phase difference of the Fresnel base sheet 111 is expressed by R, uneven brightness and irregular color in the transmission type screen 100 caused by the polarization characteristics of the image light and the double refraction of the Fresnel base sheet 11 can be reduced, then, a rear projection television 1 of high image quality can be provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a Fresnel base sheet used as a base member of a Fresnel lens sheet having a Fresnel lens shape formed on the exit side, and a Fresnel lens sheet, a transmissive screen, and a rear projection display device using the same. is there.

2. Description of the Related Art Conventionally, a rear projection display device such as a rear projection television includes a light source for projecting image light, a transmission screen disposed on the image light image formation surface, and the like. A Fresnel lens sheet that emits image light to the observation surface side (exit side) and a lenticular lens sheet having a diffusion effect for diffusing the image light are used as a set of transmission screens.
In recent years, rear projection televisions of this type tend to be thinner and have a larger screen, so the projection distance of video light has become shorter, and the Fresnel lens provided on the light source side (incident side) of the transmissive screen The incident angle of the image light with respect to the sheet is increasing.

With this increase in screen size and thinning, the light source for projecting image light is not a CRT light source that has been used in the past, but it is a compact, brighter, higher quality image that can be provided by LCD, DMD, etc. Is used.
Here, since the LCD light source includes a polarizer or the like in the process of projecting image light, color unevenness, luminance unevenness, and the like due to polarization characteristics, which did not occur with a conventional CRT light source, are generated. There was a problem. It is known that the luminance unevenness and the color unevenness are particularly remarkable particularly in the outer peripheral portion of the transmission screen where the incident angle of the image light to the transmission screen is large.

  As a cause of such luminance unevenness and color unevenness, the influence of the birefringence of the Fresnel base sheet used as the base member of the Fresnel lens sheet on the image light, and the S-polarized component and the P-polarized component included in the polarized light The influence of the difference in transmittance on image light is regarded as important.

In Patent Document 1, the incident light having a specific polarization plane has an incident angle of 20 ° or more and a total reflection angle or less with respect to the Fresnel surface of the Fresnel lens sheet (incident side surface of the Fresnel lens portion). By using a Fresnel lens sheet in which the birefringence of the substrate of the lens sheet is 350 nm or less, luminance unevenness and color unevenness are reduced.
However, in the method disclosed in Patent Document 1, when the wavelength is 700 nm, the phase difference generated in the light is 350 nm, which is equal to the half wavelength, and the polarization state is greatly changed, so that the brightness is lowered. was there.

In Patent Document 2, the rate of change due to the birefringence position at a wavelength of 590 nm is 40 nm / cm or less, the maximum birefringence amount of the base sheet for a Fresnel lens sheet is 1000 nm or less, and the maximum value of the incident angle of image light on the Fresnel lens surface is 0 °. A method for reducing color unevenness by using a Fresnel lens sheet having a angle of 38 ° or less is disclosed.
However, the method disclosed in Patent Document 2 is limited to the case where the maximum incident angle is not less than 0 ° and not more than 38 °, and color unevenness occurs when the incident angle of video light is larger. There was a problem to do. Further, the birefringence amount in the base sheet has a problem in that uneven brightness tends to occur because the in-plane distribution is not uniform.

JP 2002-90891 A JP 2004-85736 A

FIG. 7 is a diagram showing changes in the transmittance depending on the incident angles of S-polarized light, P-polarized light, and circularly polarized light.
In FIG. 7, the vertical axis represents the transmittance, the horizontal axis represents the incident angle, and represents the transmittance when the light having a refractive index of 1.00 is incident on the Fresnel base sheet having a refractive index of 1.55. The transmittance when the light is incident on the Fresnel base sheet from the air and is emitted again to the air is the square of the value shown in FIG.
As shown in FIG. 7, as the incident angle of P-polarized light and S-polarized light increases, the transmittance of P-polarized light becomes higher than that of S-polarized light, and the value of circularly polarized light becomes a value therebetween.

Since the Fresnel base sheet is subjected to processing such as stretching in the manufacturing process, it has birefringence. Therefore, when the image light incident on the Fresnel base sheet is polarized light, the polarization state changes between the entrance interface and the exit interface due to a phase difference (birefringence phase difference) caused by the birefringence.
For this reason, there is a problem that uneven luminance and uneven color occur due to the difference in polarization state and the difference in transmittance between P-polarized light, S-polarized light, and circularly polarized light at the entrance and exit interfaces of the Fresnel base sheet. It was.

  An object of the present invention is to provide a Fresnel base sheet that can reduce luminance unevenness and color unevenness caused by polarization characteristics of image light and birefringence of the Fresnel base sheet, and a Fresnel lens sheet and a transmission screen using the same. It is to provide a rear projection type display device.

The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to the Example of this invention is attached | subjected and demonstrated, it is not limited to this.
The invention of claim 1 is a Fresnel base sheet used as a base member of a Fresnel lens sheet having a Fresnel lens shape formed on the exit side, and its birefringence phase difference R is π−π / 2 ≦ R ≦. It is a Fresnel base sheet (111) characterized by satisfying π + π / 2.
The invention according to claim 2 is the Fresnel base sheet according to claim 1, wherein the birefringence retardation R is uniform at any position in the plane. 111).
The invention according to claim 3 is the Fresnel base sheet according to claim 1 or 2, wherein the refractive index n satisfies 1.45 ≦ n ≦ 1.65. It is.
The invention of claim 4 is the Fresnel base sheet (111) according to any one of claims 1 to 3, and a Fresnel lens portion (112) formed on the exit side of the Fresnel base sheet. And a Fresnel lens sheet (110).
According to a fifth aspect of the present invention, in the Fresnel lens sheet according to the fourth aspect of the present invention, the Fresnel lens sheet is used for a transmissive screen used in a rear projection display device in which the maximum incident angle of image light projected onto the transmissive screen exceeds 45 °. This is a Fresnel lens sheet (110).
The invention of claim 6 is a transmission screen (100) comprising the Fresnel lens sheet (110) according to claim 4 or 5, and an optical sheet (120) for diffusing light.
The invention of claim 7 is a rear projection display device (1) comprising the transmission screen (100) according to claim 6 and a light source (20) for projecting image light.

According to the present invention, the following effects can be obtained.
(1) Since the birefringence phase difference R of the Fresnel base sheet of the present invention satisfies π−π / 2 ≦ R ≦ π + π / 2, the image light incident on the Fresnel base sheet as circularly polarized light is Video light that is emitted as a substantially circularly polarized light in the reverse direction and incident as linearly polarized light is emitted as a substantially linearly polarized light having a polarization plane in a direction orthogonal to the polarization plane of the linearly polarized light at the incident interface. Accordingly, the sum of reflection losses at the entrance interface and the exit interface is substantially equal for the components of S-polarized light and P-polarized light (polarized light having polarization planes orthogonal to each other) that form polarized light, and the transmittance is substantially equal. Therefore, luminance unevenness and color unevenness caused by the polarization characteristics of image light can be reduced.
(2) Since the birefringence phase difference R of the Fresnel base sheet of the present invention is uniform at any position in the plane, in-plane unevenness such as luminance caused by the polarization characteristics of image light is generated. Can be reduced.
(3) Since the refractive index n of the Fresnel base sheet of the present invention satisfies 1.45 ≦ n ≦ 1.65, a commonly used Fresnel base sheet material can be used, and the manufacture is easy. Therefore, the production cost can be suppressed.
(3) The Fresnel lens sheet of the present invention is used for a transmissive screen used in a rear projection display device in which the maximum incident angle of image light projected onto the transmissive screen exceeds 45 °. When the incident angle of the image light on the transmissive screen becomes 45 ° or more, the polarization characteristics of the image light begin to have a greater influence on the image quality of the transmissive screen. Therefore, even in such a transmission screen and a rear projection display device having a large incident angle, luminance unevenness and color unevenness caused by the polarization characteristics of image light can be reduced, and the rear projection television has a larger screen. Thinner.

  The present invention relates to a Fresnel base sheet capable of reducing brightness unevenness and color unevenness caused by polarization characteristics of image light and birefringence of the Fresnel base sheet, and a Fresnel lens sheet and a transmission screen using the same. For the purpose of providing a rear projection display device, it is assumed that the birefringence phase difference R of the Fresnel base sheet satisfies π−π / 2 ≦ R ≦ π + π / 2, and a Fresnel lens sheet using the same, transmission This is realized by using a mold screen and a rear projection display device.

FIG. 1 is a diagram schematically showing a cross section of a rear projection television using a Fresnel base sheet according to the present invention.
The rear projection television 1 includes a light source device 20, a mirror 30, and a transmissive screen 100. The light source device 20 is an LCD light source, and the transmissive screen 100 is disposed on the image plane of the image light A projected from the light source device 20.

FIG. 2 is a view showing a transmission screen using the Fresnel base sheet according to the present invention.
The transmission screen 100 includes a Fresnel lens sheet 110 and a lenticular lens sheet 120.
The Fresnel lens sheet 110 is disposed on the incident side (light source side) of the transmissive screen 100 and includes a Fresnel base sheet 111 and a Fresnel lens portion 112. The Fresnel base sheet 111 is a sheet-like member used as a base member of the Fresnel lens sheet 110, and the Fresnel lens-shaped Fresnel lens portion 112 on the emission side (observation surface side) is an acrylic ultraviolet curable resin or the like. Are formed integrally.

  The lenticular lens sheet 120 is an optical sheet that diffuses light. This lenticular lens sheet 120 has a lenticular lens portion 121 for diffusing the image light A in the horizontal direction of the transmission screen 100 on the incident side surface, and a predetermined area in a region where the image light A does not pass on the emission side surface. A light shielding layer 122 having a width is provided in stripes at predetermined intervals in the horizontal direction of the transmissive screen.

  Since the image light A is emitted as substantially parallel light by the Fresnel lens unit 112, it enters the lenticular lens sheet 120 at an incident angle of approximately 0 °. However, since the incident angle of the image light A with respect to the Fresnel lens sheet 110 is large, the influence of the polarization characteristics of the image light A and the birefringence of the Fresnel base sheet 111 on the image quality is greater than that of the lenticular lens sheet 120. . Therefore, the birefringence that affects the image light A may be considered for the Fresnel base sheet 111.

(Birefringence phase difference)
First, the birefringence phase difference R that is one of the parameters indicating birefringence will be described.
A birefringent member has a different refractive index depending on the vibration direction of light. Therefore, the P-polarized light component of the polarized light passing through the member having birefringence (a linearly polarized light component oscillating in the same plane as the plane formed by the traveling direction of the light beam and the normal of the incident surface) and the S-polarized light component (of the light beam) A phase difference occurs between the traveling direction and a linearly polarized light component oscillating in a plane perpendicular to the plane formed by the normal of the incident surface, and the polarization state changes. At this time, a phase difference caused by birefringence between the P-polarized component and the S-polarized component is a birefringent phase difference R.
This birefringence phase difference R is obtained when linearly polarized light having a phase difference of 0 between the P-polarized component and the S-polarized component is incident on the birefringent member and exits through the member. This is equivalent to the phase difference generated between the P-polarized component and the S-polarized component at the exit interface.

FIG. 3 is a diagram schematically illustrating how the polarized light enters the Fresnel base sheet.
In FIG. 3, although there is a deviation in the emission position of the P-polarized component and the S-polarized component, the Fresnel base sheet 111 is sufficiently thin and may be regarded as having no deviation in the emission position.
The birefringence phase difference R is such that the wave number of the incident linearly polarized light B ₁ is k, the wavelength is λ, the incident angle is θ, the distances through which the P-polarized component and S-polarized component pass at the incident interface are L _P , L _S , When the refractive indexes of the Fresnel base sheet 111 with respect to the vibration direction of the P-polarized component and the S-polarized component are n _P and n _S , respectively, and the thickness of the Fresnel base sheet 111 is d, the following expression is obtained.
R = | ΔnkL | = | n _P kL _P −n _S kL _S |
= | N _P 2πd / (λcos (sin ⁻¹ ((sin θ) / n _P ))) − n _S 2πd / (λ cos (sin ⁻¹ ((sin θ) / n _S ))) | )
Depending on the magnitude of the birefringence phase difference R, the polarization state of the polarized light B _{2 that} has passed through the Fresnel base sheet 111 changes, for example, linearly polarized light becomes circularly polarized light.

(Polarization state and transmittance)
Next, the polarization state and transmittance at each interface of the Fresnel base sheet 111 will be described.
When the image light A having polarization characteristics passes through the Fresnel base sheet 111, the transmittance varies at the incident interface and the output interface of the Fresnel base sheet 111 depending on the polarization state at the interface.
For example, when the image light A that is circularly polarized at the entrance interface becomes linearly polarized at the exit interface due to the birefringence phase difference R of the Fresnel base sheet 111, the linearly polarized P-polarized component and S-polarized component at the exit interface Since there is a difference in reflection loss (transmittance), luminance unevenness and color unevenness occur. Similarly, when the image light A that was linearly polarized at the entrance interface becomes circularly polarized at the exit interface due to the birefringence phase difference R of the Fresnel base sheet 111, the P-polarized component of the linearly polarized light at the entrance interface, Due to the difference in reflection loss of the S-polarized component, uneven brightness and uneven color occur.

  However, when the image light A is incident on the Fresnel substrate sheet 111 with linearly polarized light, the polarization state of the image light A changes due to the birefringence phase difference R of the Fresnel substrate sheet 111, and a straight line at the incident interface is formed at the exit interface. If linearly polarized light having a polarization plane orthogonal to the polarization plane of polarized light is obtained, reduction in luminance unevenness and color unevenness can be expected. This is because the P-polarized component and the S-polarized component at the incident interface are emitted as linearly polarized light having a polarization plane in a direction orthogonal to the polarization plane of the linearly polarized light at the incident interface, respectively. This is because it corresponds to the P-polarized light component, and the total amount of reflection loss generated at the incident interface and the outgoing interface of these two polarized light components becomes equal.

  In addition, when the image light A is circularly polarized and enters the Fresnel base sheet 111, the polarization state changes due to the birefringence phase difference R of the Fresnel base sheet 111 and becomes circularly polarized at the exit interface, or the reverse direction. If it is circularly polarized light, it can be expected to reduce luminance unevenness and color unevenness. This is because the polarization plane of circularly polarized light is constantly rotating.

  Therefore, the birefringence phase difference R of the Fresnel base sheet 111 is used to define the polarization state at the entrance interface and the exit interface, and the component amounts of the P-polarized component and S-polarized component of the polarized light emitted from the Fresnel base sheet 111 In order to reduce the luminance unevenness and the color unevenness by equalizing the ratio, when the light is incident on the Fresnel base sheet 111 with linearly polarized light, the light is emitted as linearly polarized light having a polarization plane orthogonal to the polarization plane of the incident linearly polarized light. However, when the light is incident as circularly polarized light, it may be emitted as circularly polarized light that is reverse to the incident circularly polarized light. Therefore, it is theoretically considered that the birefringence phase difference R = π is optimal. Therefore, the value of the birefringence phase difference R effective for reducing the luminance unevenness and the color unevenness was examined.

(Measurement example)
Here, in order to obtain the optimal birefringence phase difference R for reduction of luminance unevenness and color unevenness, the Fresnel base sheet of Measurement Example 1 formed of a polycarbonate resin having a refractive index of 1.585 with respect to light of 589 nm, A Fresnel base sheet of Measurement Example 2 formed of cellulose acetate propionate resin having a refractive index of 1.475 with respect to light of 589 nm was prepared, and each birefringence phase difference R changed from 0 ° to 360 °. In this case, the difference in transmittance between S-polarized light and P-polarized light was obtained by calculation. The difference in transmittance between S-polarized light and P-polarized light was calculated assuming that linearly polarized light corresponding to S-polarized light and P-polarized light was projected.

(Measurement result)
FIG. 4 is a diagram showing measurement results of the Fresnel base sheet of Measurement Example 1.
4A and 4B, the horizontal axis represents the birefringence phase difference R of the Fresnel base sheet of Measurement Example 1, and the vertical axis represents S at the incident interface of the Fresnel base sheet of Measurement Example 1. Difference in transmittance when polarized components corresponding to polarized light and P polarized light pass through the Fresnel base sheet in Measurement Example 1 (value obtained by subtracting the transmittance of the component corresponding to P polarized light from the transmittance of the component corresponding to S polarized light) ). FIG. 4A shows the measurement results from an incident angle of 0 ° to 40 °, and FIG. 4B shows the measurement results from an incident angle of 50 ° to 80 °.

FIG. 5 is a diagram showing the measurement results of the Fresnel base sheet of Measurement Example 2.
FIG. 5A shows measurement results from an incident angle of 0 ° to 40 °, and FIG. 5B shows measurement results from an incident angle of 50 ° to 80 °.
5A and 5B, the horizontal axis indicates the birefringence phase difference R of the Fresnel base sheet of Example 2, and the vertical axis indicates the Fresnel base sheet of Measurement Example 2, as in FIG. Difference in transmittance when the polarized components corresponding to S-polarized light and P-polarized light at the incident interface pass through the Fresnel base sheet of Measurement Example 2 (from the transmittance of the component corresponding to S-polarized light to the component corresponding to P-polarized light The value obtained by subtracting the transmittance).

  FIG. 6 is a diagram showing the birefringence phase difference R that minimizes the transmittance difference between the S-polarized light and the P-polarized light at each incident angle. FIG. 6A shows the Fresnel base sheet of Measurement Example 1, and FIG. 6B shows the Fresnel base sheet of Measurement Example 2.

  From the measurement results shown in FIG. 4 to FIG. 6, the transmittance difference between the component incident as S-polarized light and the component incident as P-polarized light at the incident interface becomes zero in any measurement example. When the angle is from 40 °, the birefringence phase difference is around 110 ° and around 250 °. When the incident angle is from 50 ° to 70 °, the birefringence phase difference is around 120 ° and around 230 °. The phase difference was around 180 °.

Here, regarding the Fresnel base sheet, if the transmittance difference between S-polarized light and P-polarized light is within about 20%, uneven luminance and uneven color are acceptable. Therefore, when the range of the birefringence phase difference R in which the transmittance difference between the S-polarized light and the P-polarized light is within the allowable range is obtained for the Fresnel base sheet of Measurement Example 1 and Measurement Example 2, the Fresnel of Measurement Example 1 is obtained. In the base material sheet, 110 ° ≦ R ≦ 250 °, and in the Fresnel base material sheet of Measurement Example 2, 110 ° ≦ R ≦ 250 °.
The above-mentioned conditions vary depending on the material used for the Fresnel base sheet, the incident angle when actually used as a transmission screen, etc., but the range of the birefringence phase difference R of the Fresnel base sheet is 90 ° = π. If −π / 2 ≦ R ≦ 270 ° = π + π / 2, luminance unevenness and color unevenness are acceptable. In addition, when the luminance unevenness and the color unevenness are further reduced to obtain a high-quality transmission type screen, it is desirable that the birefringence phase difference R of the Fresnel base sheet satisfies 110 ° ≦ R ≦ 250 °.

Regarding the Fresnel base sheet of Measurement Example 1, when the birefringence phase difference R satisfies π−π / 2 ≦ R ≦ π + π / 2, the maximum transmittance difference between S-polarized light and P-polarized light is 22.9%. Met. However, when the birefringence phase difference R does not satisfy π−π / 2 ≦ R ≦ π + π / 2, the transmittance difference between the S-polarized light and the P-polarized light is 47.6% at the maximum, resulting in luminance unevenness and color unevenness. Degradation of image quality due to etc. was great.
Regarding the Fresnel base sheet of Measurement Example 2, when the birefringence retardation R satisfies π−π / 2 ≦ R ≦ π + π / 2, the maximum transmittance difference between S-polarized light and P-polarized light is 19.5%. Met. However, when the birefringence phase difference R does not satisfy π−π / 2 ≦ R ≦ π + π / 2, the maximum transmittance difference between the S-polarized light and the P-polarized light is 44.7%. Similar to the base sheet, the image quality was greatly degraded due to uneven brightness and uneven color.
Therefore, in order to reduce the luminance unevenness generated on the transmission screen 100 of the rear projection television 1, the birefringence phase difference R of the Fresnel base sheet 111 satisfies π−π / 2 ≦ R ≦ π + π / 2. It is valid.

In general, when the refractive index is high, the transmittances of P-polarized light and S-polarized light both tend to be low. Therefore, the Fresnel base sheet of Measurement Example 1 has a refractive index of 1.585 with respect to 589 nm light, and Fresnel of Measurement Example 2. If the Fresnel substrate sheet has a refractive index of 1.45 or more and 1.65 or less, including a refractive index of 1.475 with respect to 589 nm light of the substrate sheet, it is between P-polarized light and S-polarized light. The birefringence phase difference R that minimizes the transmittance difference satisfies π−π / 2 ≦ R ≦ π + π / 2, and is effective in reducing the transmittance difference.
Further, the birefringence phase difference R takes a value satisfying π−π / 2 ≦ R ≦ π + π / 2 and is uniformly distributed in the plane of the Fresnel base sheet 111. Reduction of unevenness can be expected.
Further, this birefringence phase difference R satisfies π−π / 2 ≦ R ≦ π + π / 2 for image light in the range of 400 to 700 nm, which is the wavelength region of visible light, regardless of the wavelength. Therefore, it can be expected to reduce color unevenness.
For example, in the case of a Fresnel lens sheet having a refractive index of 1.585 with respect to 589 nm light, the refractive index varies from 1.58 to 1.60 with respect to 400 to 700 nm light. 1.45 or more and 1.65 or less are satisfied.
The Fresnel lens sheets of Measurement Example 1 and Measurement Example 2 have a refractive index of 1.475 and 1.585 for light of 589 nm, which are greatly different. However, because the difference in transmittance difference is about several percent, the difference in transmittance due to the difference in refractive index depending on the wavelength is even smaller and is not particularly limited.

  From the above, when the birefringence phase difference R of the Fresnel base sheet 111 satisfies π−π / 2 ≦ R ≦ π + π / 2, the polarization characteristics of the image light and the birefringence of the Fresnel base sheet This is effective in reducing luminance unevenness and color unevenness of the transmissive screen 100 due to the above.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications and changes are possible, and these are also within the equivalent scope of the present invention.
In the present embodiment, the Fresnel base sheet uses an example of using a polycarbonate resin or a cellulose acetate propionate resin. However, the present invention is not limited to this. For example, an acrylic resin or a styrene resin may be used.

It is a figure which shows typically the cross section of the rear projection television using the Fresnel base material sheet by this invention. It is a figure which shows the transmission type screen using the Fresnel base material sheet by this invention. It is the figure which showed typically a mode that polarized light entered into a Fresnel base material sheet. It is a figure which shows the measurement result of the Fresnel base material sheet of the measurement example 1. It is a figure which shows the measurement result of the Fresnel base material sheet of the measurement example 2. It is a figure which shows the birefringent phase difference R from which the transmittance | permeability difference of S polarized light and P polarized light becomes the minimum in each incident angle. It is a figure which shows the change of the transmittance | permeability by the incident angle of S polarized light, P polarized light, and circularly polarized light.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rear projection television 20 Light source device 30 Mirror 100 Transmission type screen 110 Fresnel lens sheet 111 Fresnel base material sheet 112 Fresnel lens part 120 Lenticular lens sheet 121 Lenticular lens part 122 Light-shielding layer

Claims (7)

A Fresnel base sheet used as a base member of a Fresnel lens sheet formed on the exit side with a Fresnel lens shape,
The birefringence phase difference R satisfies π−π / 2 ≦ R ≦ π + π / 2,
Fresnel base sheet characterized by this. In the Fresnel base sheet according to claim 1,
The birefringence phase difference R is uniform at any position in the plane,
Fresnel base sheet characterized by this. In the Fresnel base sheet according to claim 1 or 2,
The refractive index n satisfies 1.45 ≦ n ≦ 1.65,
Fresnel base sheet characterized by this. The Fresnel base sheet according to any one of claims 1 to 3,
A Fresnel lens portion formed on the exit side of the Fresnel base sheet;
Fresnel lens sheet with In the Fresnel lens sheet according to claim 4,
Used for a transmissive screen used in a rear projection display device in which the maximum incident angle of image light projected onto the transmissive screen exceeds 45 °;
Fresnel lens sheet characterized by The Fresnel lens sheet according to claim 4 or 5,
An optical sheet that diffuses light;
Transmission type screen with The transmission screen according to claim 6;
A light source for projecting image light;
A rear projection type display device.

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