JPH10339915A - Back projection screen and its production, and picture display device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection screen for restraining moire trouble to tolerance so that the trouble may not be caused in terms of practical use. SOLUTION: This screen has laminating structure where a lenticular lens 15 sheet provided with a lenticular lens array 16 whose array pitch Ps is <=0.2 mm on either surface and provided with a light diffusing layer 14 and a light absorbing layer 13 on the other flat surface and having 0.3 mm thickness is optically coupled with a light transmissive member 11 having 1 mm to 5 mm thickness on the surface of the layer 13 with transparent adhesive 12. Then, the ratio of the pitch of the lenticular lens 15 to that of a picture element on the screen is selected to be very high so that moire may not occur.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear projection screen used for a rear projection type image display device, a method of manufacturing the same, and a rear projection type image display device using the same.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand from the market for developing a lightweight and compact rear projection type image display apparatus for displaying a large screen image. In the rear projection type image display device,
FIG. 7 schematically shows a state in which the rear projection screen is used.

[0003] An image on the CRT 201 is enlarged and projected by the projection lens 202 from the rear side of the rear projection screen 203, and formed on the rear projection screen 203. The user can watch the image formed from the front of the screen. When an image is viewed from a direction deviated from a direction directly facing the screen, the luminance of the image generally decreases in accordance with the deviation. The state of the change in the luminance is called a visual field characteristic. The rear projection screen 203 includes a Fresnel lens sheet 204 and a lenticular lens sheet 205.
It consists of. The Fresnel lens sheet 204 converts the projection light incident on the rear projection screen 203 from the projection lens 202 into substantially parallel light. Fresnel lens sheet 20
The incident light that has been converted into a parallel light beam at 4 is diffused by the lenticular lens sheet 205. The viewing characteristics of the screen are determined by the manner in which the incident light is diffused.

The lenticular lens sheet 205 is formed with a semi-cylindrical lenticular lens array arranged on the rear surface of the sheet with the vertical direction as the longitudinal direction, and a diffusing material is dispersed inside the lenticular lens sheet 205. .

[0005] The horizontal viewing angle is mainly obtained by refraction by a lenticular lens and is relatively wide, but diffusion by a diffusing material also contributes to expansion of the viewing angle. The vertical viewing angle is obtained only by the diffusion effect of the diffusion material, and is relatively narrow. The image display device sets the viewing angle of the screen in accordance with the viewing environment, thereby effectively utilizing the projection light to increase the brightness of the viewing area.

[0006] The view characteristics of the screen display device are preferably as wide as possible in terms of the range that can be viewed with respect to the screen, but the frontal luminance decreases as the view characteristics are widened. Therefore, the preferred viewing characteristics are
It is determined by effectively distributing the light in the required direction.

The screen of the screen display device is generally viewed from various angles in the horizontal direction. However, in the vertical direction, it is expected that the viewer will be viewed in a limited angle range that can be viewed from a sitting state or a standing state, so that the vertical viewing characteristics need not be wide. The viewing characteristics of rear projection screens are designed to meet their intended use. Therefore, the light diffusion characteristics of the rear projection screen require anisotropic diffusion characteristics that are wide horizontally and vertically narrow.

The lenticular lens sheet realizes its anisotropic light diffusion characteristics. That is, the light diffusion characteristic in the horizontal direction shows a large value in the horizontal direction due to the action of the lenticular lens having the vertical direction as the longitudinal direction, and a relatively small value in the vertical direction due only to the action of the light diffusion material disposed inside. Show.

The operation of the lenticular lens of the lenticular lens sheet 205 will be described with reference to FIG. Note that FIG. 8 does not show a light diffusing material that is usually blended, and thus only shows light diffusion in the horizontal direction due to the refraction of the lenticular lens.

[0010] In Fig. 8, the ray trajectory indicated by a solid line indicates a principal ray passing through the center of the pupil of the projection lens 202, and the broken line indicates a ray passing through the periphery of the projection lens.

As is apparent from the figure, the incident light that is incident on the light beam with a very directivity sharp (almost parallel) is diffused widely (at a wide angle) by the lenticular lens so that the image can be viewed from a wide field of view. become.

Since the thickness of the lenticular lens sheet 205 is substantially equal to the focal length of the lenticular lens, the projected light exits from a specific area on the exit surface of the lenticular lens sheet 205 and does not exit from other areas. Utilizing the fact that light is not emitted from this specific area (light opaque area), it is common practice to form a black stripe 206 using a light absorbing material in the light opaque area on the emission surface.

The lenticular lens sheet 205 can reduce the reflection of external light without losing the projected light by forming the black stripe 206 as described above.
The contrast of an image can be greatly improved.

However, as is clear from the above description,
The thickness of the lenticular lens sheet 205 needs to be approximately equal to the focal length of the lenticular lens element,
Appropriate horizontal viewing angle (± 30 ° to 4 at the angle at which the luminance is halved)
When setting 5 す る と), the lenticular lens pitch is 1.2
Times to 1.5 times.

The screen size of this type of device, typically a rear projection television, is typically 35 to 70 inches, while the lenticular lens pitch is 0.5 to 1.0.
mm.

The smaller the lenticular lens pitch is, the less the resolving power is reduced by the rear projection screen, and it is preferable that the CRT is used as an image source at the lenticular lens pitch of 0.5 to 1.0 mm. In the rear projection type image display device, a display quality having no practical problem has been obtained.

However, as is clear from the above description,
The black stripe must be formed so as to maintain a correct positional relationship with the corresponding lenticular lens. If the position is shifted, the light beam that should be emitted is absorbed, and the light efficiency is reduced.

The most common method of forming a black stripe is to form a lenticular lens sheet and to integrally form irregularities at a corresponding position on an emission surface together with the shape of the incident lenticular lens, and use the irregularities. Is the way. 0.5 which is currently commonly used in this method
The positional accuracy of the lenticular lens pitch from 1.0 mm to 1.0 mm has been obtained for the time being. However, the positioning accuracy between the mold that forms the lenticular lens shape and the mold that forms the irregularities is limited by the processing accuracy, and if the lenticular lens pitch is further reduced, the relative positional error increases, and the alignment accuracy is further reduced. It is becoming difficult to make a lenticular lens pitch.

Japanese Patent Application Laid-Open No. 8-254756 discloses a method of forming a black stripe at an accurate position irrespective of a mold by selectively exposing a photosensitive resin by a light condensing function of a lenticular lens. A method of forming a mask and using the same is disclosed.

[0020]

However, in recent years, a rear projection type image display device using a liquid crystal as an image source has been developed, and a finer lenticular lens pitch has been required. This is because in a rear projection type image display device using a liquid crystal as an image source, moire may be generated between the pixel arrangement of the liquid crystal and the lens arrangement of the lenticular lens. Until then, CRT
In the rear projection type image display device using the image source as the image source, the moiré did not occur because the periodicity of the scanning line of the CRT and the periodicity of the lenticular lens were spatially orthogonal to each other.

The moire caused by the pixel arrangement of the liquid crystal and the lens arrangement of the lenticular lens is related to the pitch ratio Rp = Pg / Ps between the pixel pitch Pg of the liquid crystal on the screen and the lenticular lens pitch Ps of the lenticular lens sheet. To make it less noticeable
The pitch ratio Rp is preferably a value close to a half-integer multiple, and the moire intensity decreases as the pitch ratio Rp increases.

Although the value of the pitch ratio Rp which does not cause a practical problem cannot be determined unconditionally in relation to the amount of the diffusing material to be mixed, according to our study, If it is less than 5, optimization by the half-integer value is required, and it is preferably about 4.5, and at least 2.5 or more.
When Rp is 5.5 or more, the moiré intensity becomes small, and the optimization by the half-integer value becomes unnecessary.

For example, the most common VGA (VIDEO GRA
When displaying an image of PHICS ARRY (640 horizontal pixels, 480 vertical pixels) specification on a rear projection type image display device using a liquid crystal as an image source with a screen size of 40 inches, the pixel pitch Pg on the rear projection screen is as follows. About 1.3mm
It is. Therefore, the maximum value of the usable lenticular pitch Ps is about 0.5 mm, which is 1/2. The lenticular pitch Ps of 0.5 mm can be accommodated by a lenticular lens sheet generally used at present.

However, as described above, in order for the lenticular lens sheet having a black stripe to maintain a predetermined viewing angle, the thickness of the lenticular lens sheet must be within 1.5 times the lenticular pitch, that is, 0.1 mm. It becomes 75 mm or less.

Such a lenticular lens sheet having a thickness of 0.75 mm or less causes a new problem that it is very flexible and difficult to hold.

Further, the lenticular lens sheet having a pitch of 0.5 mm can be used only with the number of pixels and the screen size. If the screen size is slightly different even with the same number of pixels, a moire having a large pitch is generated and cannot be used.

In the prior art, a diffusing material is disposed inside a lenticular lens sheet. In this case,
Due to the diffusing action of the diffusing material, the projected light reaches the black stripe portion in a diffused state, causing light loss.
Further, Japanese Patent Application Laid-Open No. 8-254756 discloses a method of forming a concavo-convex pattern or mask by selectively exposing a photosensitive resin by a light-condensing function of a lenticular lens in generating a black stripe. ing.

However, in this method, similarly, when a diffusing material is disposed inside the lenticular lens sheet, the irradiation light is diffused by the diffusing action of the diffusing material, and the exposure light such as the intensity of the irradiation light, the exposure time, etc. Slight changes in conditions,
Due to unevenness, it changes to the formation state of black stripe,
There is also a problem that unevenness occurs and it is difficult to form a stable black stripe.

In order to avoid these problems, a method of forming the lenticular lens sheet using only a transparent material and disposing the diffusion plate 108 on the side where the screen is viewed as shown in FIG.

However, in this method, diffuse reflection of external light cannot be sufficiently reduced, and the contrast of an image is reduced.

The basic concept will be described with reference to FIGS. 6A and 6B using a flat plate as a model.

FIG. 6 (A) shows a light-diffusing layer formed inside a transparent plate having a black stripe, and FIG. 6 (B)
In the figure, a diffusion plate is arranged in front of a transparent plate on which black stripes are formed. 107 is a light diffusion layer 110 at the center.
The other is a diffusion plate with a black stripe in which a black stripe 106 is formed on the surface of the transparent diffusion plate on the side on which the screen is viewed. The diffusion plate 108 has a light diffusion layer 110 in the center, and the others are transparent.
06 is a transparent plate with a black stripe, and the width of the black stripe 106 is half the period of the black stripe.

In the above model, the refractive index of the transparent material is 1.5
For convenience, it is assumed that the reflectance is 4% regardless of the angle of incidence and there is no absorption, and each surface is a mirror surface. The reflectance of the black stripe portion is 4%, and the others are absorbed and the transmittance is zero. Black stripes are formed on the black stripe surfaces 107a and 109a at a rate of 50%. The reflectance is 4%, the transmittance is 48%, the absorption is 48%, and the other surfaces on which no black stripe is formed have a reflectance of 4%. %, The transmittance is 96%, and the absorption is 0%.

Under the above assumptions, FIGS. 6A and 6
The diffuse reflection components in the two models (B) are examined. Note that the intensity of the incident light is set to 1, and the component reflected a plurality of times is ignored as a minute component.

In FIG. 6A, the black stripe surface 107 on the side where the screen of the diffusion plate 107 with the black stripe is viewed is shown.
It is assumed that external light having a light intensity of 1 is incident on a. 4% of the incident light is reflected, 48% is absorbed and 48% is transmitted and diffused by the light diffusion layer 110. 4% of the diffused 48% light is reflected by the 107b surface, and 48% of the
Is transmitted again through the black stripe surface 107a and returned to the observation direction. The component returning to the observation direction is (1) 10
The component transmitted through the surface 7a, reflected on the surface 107b, and transmitted through the surface 107a again is 0.04 × (0.48) 2 = 0.009, which is only 0.9% of the incident external light.

On the other hand, when the same examination is performed in FIG. 6B, 4% of the external light incident on the surface 108a of the diffusion plate 108 on the side of viewing the screen is reflected and 96% transmitted, and the external light is transmitted through the light diffusion layer 110. Spread. Of the 96% of the light diffused by the light diffusion layer 110, the component returned to the observation direction is (1) a component reflected on the 108b surface and transmitted through the 108a: 0.04 × 0.96 = 0.038 (2) 108b surface is transmitted, 109a surface is reflected, 108
0.04 × (0.96) 3 = 0.035 (3) Components that transmit through surfaces 108b and 109a, reflections through surface 109b, and components that transmit through surfaces 109a, 108b, and 108a. 04 × (0.96) 3 × (0.48) 2 = 0.008 and 0.96 × (0.038 + 0.035 + 0.008) =
0.078 That is, in the model of FIG. 6B, about 9% of the light of about 8% of the model of FIG. 5A and about 8% of the light is reflected to the viewer's side as diffused light. Deteriorate.

The method of disposing the diffusion plate in front of the lenticular lens sheet as described above has a problem of deteriorating the contrast of an image.

[0038]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lenticular lens sheet having a fine pitch of 0.2 mm or less so that moiré obstruction does not cause a practical problem. As a result, the thickness of the lenticular lens sheet must be reduced to 0.3 mm or less in order to obtain an image. It is an object of the present invention to provide a rear projection screen having a mechanical rigidity that is easy to use.

To solve this problem, a rear projection screen according to the present invention comprises a lenticular lens sheet having a lenticular lens array on one surface and a flat surface on the other surface, and a light transmitting member having flat surfaces on both surfaces. And a light-absorbing layer existing between a flat surface of the lenticular lens sheet and one surface of the light transmitting member, a light diffusing layer, and an optical coupling layer.

The rear projection screen and the method of manufacturing the same according to the present invention include the thin lenticular lens sheet and the thick light transmitting member, and include a light absorbing layer and a light diffusing layer between the lenticular lens sheet and the light transmitting member. Formed and glued to optically couple so that light does not reflect off the interface,
The integrated structure has mechanical rigidity and at the same time prevents light loss and flare due to reflection on the bonding surface.

By using the rear projection screen of the present invention, the projection type image display apparatus of the present invention can make the lenticular lens pitch finer when a liquid crystal is used as an image source.

[0042]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a lenticular lens sheet having a lenticular lens array on one surface and a flat surface on the other surface, a light transmitting member having flat surfaces on both sides, and a lenticular lens sheet. The present invention relates to a rear projection screen including a light absorbing layer existing between a flat surface and one surface of the light transmitting member, a light diffusing layer, and an optical coupling layer.

According to the present invention, there is provided a lenticular lens sheet having a lenticular lens array on one surface and a flat surface on the other surface; a light absorbing layer adjacent to the flat surface of the lenticular lens sheet; An optical coupling layer adjacent to the layer, a light diffusion layer adjacent to the optical coupling layer, and both surfaces adjacent to the light diffusion layer are formed of a flat light transmitting member, and a surface having the light absorption layer. The present invention relates to a rear projection screen in which a surface having the light diffusion layer is optically coupled.

The present invention provides a lenticular lens sheet having a lenticular lens array on the projection side and a flat surface on the other side, a light diffusion layer, and a light absorption layer in order from the projection side to the screen viewing side. And a rear projection screen comprising an optical coupling layer and a light transmitting member having flat surfaces on both sides, wherein the surface on which the light absorbing layer is formed and the light transmitting member are optically coupled.

According to the present invention, the lenticular lens sheet has a thickness substantially equal to a focal length of the lens of the lenticular lens array, and the light absorbing layer is formed in a light-impermeable region of a flat surface of the lenticular lens sheet. The present invention relates to the rear projection screen according to the invention, wherein a surface of a light diffusion layer formed on a surface on a projection side of the light transmitting member is optically coupled with a transparent adhesive.

According to the present invention, the lenticular lens sheet has a thickness substantially equal to the focal length of the lens of the lenticular lens array, and a flat surface of the lenticular lens sheet on which the light absorbing layer is formed in a light-impermeable region. The present invention relates to the rear projection screen of the invention, wherein a surface of a light diffusion layer formed on a projection side surface of the light transmitting member is optically coupled with a transparent adhesive.

According to the present invention, a step of forming a lenticular lens sheet on one surface and forming a lenticular lens sheet having a flat surface and a thickness substantially equal to the focal length of the lenticular lens by curing an ultraviolet curable resin. Forming a light-absorbing layer in a light-impermeable region of a flat surface of the transparent lenticular lens sheet by a lift-off method using an ultraviolet-curable resin; and forming the light-transmitting surface of the lenticular lens sheet with the light-absorbing layer. The present invention relates to the method for producing a rear projection screen according to the present invention, which comprises a step of joining a surface having a light diffusion layer of a member with a transparent adhesive.

According to the present invention, there is provided a process of forming a lenticular lens sheet on one surface and forming a lenticular lens sheet having a flat surface and a thickness substantially equal to the focal length of the lenticular lens by curing an ultraviolet curable resin. And providing a light diffusing layer in which a diffusing material for diffusing light isotropically dispersed on the flat surface of the transparent lenticular lens sheet; and curing the light absorbing layer in a light impermeable region above the light diffusing layer, by ultraviolet curing. The step of forming by a lift-off method using a resin, and the rear projection screen of the present invention in which the surface of the lenticular lens sheet having the light absorbing layer and the surface of the light transmitting member having the light diffusing layer are bonded with a transparent adhesive. The present invention relates to a rear projection type image display device using the same.

(Embodiment 1) FIG. 1 is a horizontal sectional view of a rear projection screen according to a first embodiment of the present invention, in which a lenticular lens sheet 15 and a light transmitting member 11 are made of a transparent adhesive 1.
It is a structure that is stuck at 2. The rear projection screen means a Fresnel lens sheet and a lenticular lens sheet as described in FIG. 6, but in the following description, the rear projection screen does not include the Fresnel lens sheet. The projection-type image display device projects an image from the lenticular lens sheet 15 side, and a viewer views the image from the light transmitting member 11 side.

On one surface of the lenticular lens sheet 15, a lenticular lens array 16 composed of lenticular lenses is formed. The lenticular lens has a semi-cylindrical shape, and many are arranged in an array. When used, the longitudinal direction of the semi-cylinder is arranged in a vertical direction.

The light diffusion layer 14 is formed on the entire other surface of the lenticular lens sheet 15. Light diffusion layer 14
Is dispersed with a diffusing material that diffuses light isotropically. The light absorption layer 13 is formed on the light diffusion layer 14. Since the light absorbing layer 13 is formed in a light-impermeable region generated as a result of the refraction of the lenticular lens sheet, the projected light is not lost. The light absorbing layer 13 is black and called a black stripe.

As described with reference to FIG. 8, the lenticular lens array 16 refracts incident light that is incident in the horizontal direction,
In the rear projection screen of the present invention, the lenticular lens pitch Ps is set to 0.2 mm or less to satisfy the above-described moiré reduction condition. The focal length of the lenticular lens is selected to be 1.2 to 1.5 times the pitch Ps. As a result, the rear projection screen of the present invention can obtain an appropriate horizontal viewing range with respect to the image display surface.

The lenticular lens array 16 refracts and diffuses the incident light horizontally to diffuse the light widely. However, the light diffusion layer 14 diffuses the light in directions other than the direction of diffusion by the lenticular lens. Also, it is possible to prevent a sudden decrease in luminance depending on the viewing angle. Further, the light is diffused in the vertical direction in which the refraction function of the lenticular lens array 16 does not act to provide a relatively small viewing area.

The thickness t1 of the lenticular lens sheet 15
Is set to a thickness equal to the focal length. As a result, the projection light is condensed on a limited area (surface) of the other surface and emitted from the limited area (plane). Therefore, the projection light passes through only a limited region (surface) on the other surface, and does not pass through the other region (surface). A region through which the light does not pass is called a light-impermeable region, and the light-absorbing layer 13 is provided in the light-impermeable region. The light absorbing layer 13 is provided with a black stripe so that the projected light is not lost. With this light absorbing layer, reflection of external light can be reduced without loss of projection light, and the contrast of an image can be improved.

As is apparent from the above description, the thickness t1 of the lenticular lens sheet 15 thus configured is 1.2 to 1.5 times the lenticular lens pitch Ps = 0.20 mm, so that the thickness t1 is at most 0.1. With this thinness, it is difficult to mount it alone as a rear projection screen on a projection type image display device.

Therefore, by bonding the lenticular lens sheet 15 to the thick light transmitting member 11, insufficient mechanical strength can be compensated. However, if the bonding condition of the two does not satisfy the optical coupling condition, light loss or flare occurs due to reflection at the bonding surface. A transparent pressure-sensitive adhesive 1 that satisfies the condition that the lenticular lens sheet 15 having a thickness t1 of 0.3 mm or less and the light transmitting member 11 having a thickness t2 of 1 mm to 5 mm can be optically coupled so that no reflection occurs at the interface.
Attach with 2 For example, an acrylic resin is used as the light transmitting member 11 and the lenticular lens sheet 15, and the light diffusing layer 1
4. If a resin containing an acrylic resin as a main component is used as the light absorbing layer 13 and an acrylic transparent adhesive is used as the transparent adhesive 12, the refractive indexes of the two are almost the same. This bonding forms an optical connection, and no light loss or flare occurs due to reflection at the connection surface. That is, in order to satisfy the optical coupling condition, the refractive indexes of the members need only be close to each other.

Since the mechanical strength of the screen is reinforced, it can be easily handled when it is mounted alone as a rear projection screen on a projection type image display device.

The thickness t2 of the light transmitting member 11 is 1 mm
If it is less than 5 mm, the strength will be insufficient, and if it is more than 5 mm, the weight will be too large, and handling will be difficult.

(Embodiment 2) FIG. 3 is a horizontal sectional view showing a rear projection screen according to a second embodiment of the present invention, in which a portion of the exit surface of the lenticular lens sheet 25 through which light does not pass, ie, a light impermeable region. A black stripe, that is, a light absorbing layer 23 is provided. A light diffusion layer 24 in which a diffusion material that diffuses light isotropically is formed on the entire surface of one surface of the light transmission member 21. The light absorbing layer 23 made of the black stripe and the light diffusing layer 24 made of the diffusing agent are optically coupled by the transparent adhesive 22 so that no reflection occurs at the interface, and the lenticular lens sheet 25 and the light transmitting member 21 are integrated. Be transformed into

With such a configuration, the lenticular lens array 26 performs the function of refracting and diffusing incident light that is incident in the horizontal direction. Since the light absorbing layer 23 is formed in the light non-transmissive region generated as a result of the refraction of the lenticular lens sheet, the projection light is not lost and the reflection of external light can be suppressed. The light diffusing layer 24 scatters the projected light because a diffusing material that diffuses light isotropically is dispersed in the light diffusing layer 24.

Further, the outside light diffused by the light diffusion layer 24 is not reflected on the black stripe surface, and the component reaching the black stripe is absorbed by 100%, and the component reaching the opening is transmitted by 100%. Can be reduced. In addition, a member in which the light diffusion layer 24 and the light transmission member 21 are integrated by double extrusion molding is manufactured, and a lenticular lens sheet having a light absorption layer is laminated with a transparent adhesive so as to be optically bonded, and integrated. good.

Although the surface of the light absorbing layer 23 and the light diffusing layer 24 are bonded by an adhesive, the same effect can be expected by using a transparent adhesive.

Next, the operation and effect of the rear projection screen of the present invention described in the first and second embodiments will be described.

First, the lenticular lens pitch Ps can be reduced to 0.2 mm or less. As a result, since the pixel pitch Pg in a rear projection type image display device having a screen size of 35 inches or more using a VGA liquid crystal panel is about 1.3 mm, the pitch ratio Pd / Ps is set to 5.5 times or more. Therefore, the moiré failure can be set within a practical range, and the first conventional problem can be solved.

Second, a lenticular lens sheet having a lenticular lens pitch Ps of 0.2 mm or less and a black stripe formed on the focal plane and having a thickness of 0.3 mm or less is used as a coupling surface with the surface on which the black stripe is formed. By using a structure that is optically bonded to a light transmitting member having a thickness of 1 mm or more, structural strength can be enhanced without impairing optical performance such as loss of light due to reflection or occurrence of flare. .

Third, by employing a structure in which the lenticular lens sheet and the light transmitting member are bonded so as to be optically coupled to each other, light loss can be reduced without impairing optical performance such as light loss or flare caused by reflection. Thus, a rear projection screen having an excellent effect of reducing external light reflection can be provided.

The light diffusion layer 24 has been described as being formed on the entire surface of one surface of the light transmitting member 21.
, The diffusing material may be dispersed throughout the lenticular lens sheet.

Further, a light absorbing material may be dispersed in the light transmitting member 21. In this case, the transmittance is reduced, but the reflection of external light can be reduced more than the loss of the projected light by the light transmitting member 21, and the contrast of the image can be improved.

Further, the rear projection screen can be provided with an added value by subjecting the surface of the light transmitting member to a known treatment such as an antireflection treatment, an antistatic treatment and a surface hardening treatment.

By using the rear projection screen having the above configuration in a rear projection type image display apparatus using a liquid crystal panel as an image source, the image quality is not limited to a screen of a specific size, and the image quality is deteriorated due to moire in various screen sizes. A rear-projection screen having excellent contrast characteristics and easy handling was obtained without causing any problem.

As described above, the rear projection screens of the first and second embodiments can be used for a rear projection type image display device as shown in FIG. The image on the liquid crystal panel 50 irradiated with the light of the lamp 51 is enlarged and projected by the projection lens 52, becomes parallel rays by the Fresnel lens sheet 54, and is formed on the lenticular lens sheet 55.

Further, in the rear projection type image display apparatus using the rear projection screen according to the first and second embodiments, the pitch ratio Pd / Ps can be made 5.5 times or more, and the moiré failure can be prevented. Within the practical range.
However, it goes without saying that the liquid crystal panel may be a video display device such as a CRT or a plasma display as shown in FIG.

(Embodiment 3) FIG. 4 is a view showing a lenticular lens sheet according to a third embodiment of the rear projection screen of the present invention.

On the flat surface side of the lenticular lens sheet 35, a black stripe is formed to form a light absorbing layer 33. A light diffusing layer 34 in which a diffusing material for diffusing light isotropically by printing, spraying or the like is directly formed thereon. At this time, the surface of the light diffusion layer 34 is made substantially smooth by setting the number of printing times to be plural or optimizing the viscosity of the spray material.

A lenticular lens sheet 35 having a light diffusion layer 34 and a light absorption layer 33 having a structure as shown in FIG.
When optically coupled with the light transmitting member, both sides are flat and have no irregularities, so no bubbles enter the transparent adhesive,
The formation of the optical coupling layer is facilitated.

(Embodiment 4) Next, a fourth embodiment of the present invention will be described with reference to the drawings. 5 (A), 5 (B), 5 (C), and 5 (D) are process diagrams showing an example of a method for manufacturing a lenticular lens sheet for a rear projection screen according to the present invention.

First, an uncured acrylic UV curable resin is filled in a mold processed into the reverse shape of the lenticular lens array, and a polyester film is placed thereon so that air bubbles do not enter the interface with the UV curable resin. Then, ultraviolet rays are irradiated from the polyester film side to cure the ultraviolet curable resin, thereby forming a film-like lenticular lens sheet 25 as shown in FIG. At this time, the thickness of the polyester film is set so that the total thickness of the lenticular lens and the polyester film substantially matches the focal length of the lenticular lens.

The light absorption layer 23 is formed on the lenticular lens sheet 25 by a lift-off method. After an ultraviolet curable resin is applied to the flat surface of the film-like lenticular lens sheet 25, ultraviolet light parallel to the optical axis of the lenticular lens is irradiated from the lenticular lens surface. By the ultraviolet irradiation, the ultraviolet curable resin in a portion that becomes a transmission portion through which light passes when used as a screen is cured. The uncured ultraviolet-curable resin that becomes a light-impermeable region through which light does not pass is removed in the developing step. In this way,
A lenticular lens sheet in which an ultraviolet curable resin is formed in a stripe shape in a light transmitting portion is obtained.

Next, a black ink is applied to the entire flat surface by printing or spraying, and dried. Using a chemical that dissolves the ultraviolet curable resin but does not dissolve the black ink, the black ink at the position corresponding to the light transmitting portion is removed together with the ultraviolet curable resin remaining in the light transmitting portion. In this way, the black ink remains only in the light-impermeable area, and FIG.
As shown in (B), a film-shaped lenticular lens sheet having a black stripe formed thereon, that is, having a light absorbing layer 23 is manufactured.

On the other hand, the light transmitting member 2 having the light diffusing layer 24
1 is manufactured by two-layer extrusion molding, and becomes as shown in FIG. The materials used here and their properties will be described. The material of the light transmitting member 21 serving as the base material is PMM.
A (acrylic resin) is used. The light diffusion layer 24 is formed by dispersing MS (polymer of acrylic and styrene) beads using PMMA as a dispersion medium. The light diffusion action is caused by the fact that the refractive index of the dispersion medium, PMMA, and that of the bead material, MS, are different, so that light is refracted at the bead interface. The desired diffusion characteristics can be obtained by adjusting the refractive index of the MS beads, the diameter of the beads, and the thickness of the dispersion layer. The refractive index of MS, which is a bead material, is 1.52 to 1.55, while the refractive index of PMMA, which is a dispersion medium, is 1.49.
If the bead particle size is set to 3 μm to 20 μm and the dispersion concentration is set to 5 to 20% in volume concentration, the thickness of the light diffusion layer becomes about 10
At 0 μm, the vertical viewing characteristics required for the screen can be realized.

Next, a light transmitting member 21 having a light diffusion layer 24 manufactured by two-layer extrusion molding (FIG. 5C).
A method for optically bonding the film-shaped lenticular lens sheet (FIG. 5B) on which the light absorbing layer 23 is formed with the transparent adhesive 22 will be described with reference to FIG. 4D.

The appropriate thickness of the light transmitting member 21 varies depending on the screen size, but after being combined with the lenticular lens sheet, a sufficient mechanical strength can be obtained as a whole, and 1 mm to 5 m so as not to be too heavy to be difficult to handle.
Set to the range of m. The lenticular lens sheet with the black stripe and the light transmitting member 21 are bonded by the acrylic transparent adhesive 22 (refractive index: 1.49) with the black stripe surface and the light diffusion layer surface as bonding surfaces.

As can be understood from the above description, each of the elements constituting the screen, that is, the lenticular lens sheet 25, the dispersion medium of the light diffusion layer 24, and the light transmitting member 21 are made of acrylic resin or acrylic resin as a main component. Yes,
The refractive index of the acrylic transparent adhesive 22 that bonds them is almost equal to that of the transparent adhesive, and satisfies the optical bonding condition, so that light is not reflected at the boundary between them.

According to this manufacturing method, an accurate and stable black stripe can be formed without the light diffusion layer becoming an obstacle in forming the black stripe. Further, since the light diffusion layer and the black stripe surface are optically coupled to each other and there is no reflective interface between them, there is no reduction in contrast due to reflection, and a high contrast image can be realized by light absorption of the black stripe.

Further, since the mechanical strength is increased by optically coupling to a diffusion plate having a relatively thick base material, the rear projection screen of the present invention can be used as a film-shaped lenticular lens sheet which is conventionally difficult to handle alone. This facilitates mounting on a projection type image display device.

In the above manufacturing method, two layers of the light diffusion layer 24 and the transparent light transmission member 21 were formed by extrusion molding. However, the film-like light diffusion layer was formed by a film-like lenticular lens sheet with black stripes. The acrylic transparent pressure-sensitive adhesive 2 is interposed between the light-transmitting member 21 which is a transparent layer.
The two may be optically coupled by 2 (refractive index: 1.49).

The film-like light diffusing layer is optically bonded to the lenticular lens sheet on which the film-like black stripe is not prepared by the acrylic transparent adhesive material 22, and the black stripe is formed thereon by the above-mentioned method. And the light transmitting member 21 may be optically coupled to the surface with the transparent adhesive 22.

As described above, according to the present invention, by setting the lenticular lens array pitch to 0.2 mm or less, image deterioration due to moire can be prevented even when used in a rear projection type image display apparatus using a liquid crystal panel as an image source. By forming a structure in which the lenticular lens sheet and the light transmitting member having a thickness of 1 mm to 5 mm are optically bonded to each other without being generated, the handling can be facilitated without impairing the optical characteristics.

[0089]

The rear projection screen and the method of manufacturing the same according to the present invention can be modified in various other ways. Accordingly, all modifications that come within the true spirit and scope of the invention are intended to be covered by the appended claims.

[Brief description of the drawings]

FIG. 1 is a horizontal sectional view of a rear projection screen according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a basic configuration of a projection type image display device of the present invention.

FIG. 3 is a horizontal sectional view of a rear projection screen according to the second embodiment of the present invention.

FIG. 4 is a cross-sectional view of a lenticular lens sheet of a rear projection screen according to a third embodiment of the present invention.

FIG. 5 is a process chart showing another embodiment of the method for manufacturing a rear projection screen according to the fourth embodiment of the present invention.

FIG. 6 is a cross-sectional view of a conventional flat plate model for explaining a diffuse reflection component of external light.

FIG. 7 is a schematic diagram showing a basic configuration of a conventional projection type image display device.

FIG. 8 is a sectional view of a lenticular lens sheet for explaining the operation of a conventional lenticular lens sheet.

[Explanation of symbols]

 11, 21 Light transmitting member 12, 22 Transparent adhesive 13, 23, 33 Light absorbing layer 14, 24, 34 Light diffusing layer 15, 25, 35 Lenticular lens sheet 16, 26 Lenticular lens array

Claims (22)

[Claims] 1. A lenticular lens sheet having a lenticular lens array on one surface and a flat surface on the other surface, a light transmitting member having flat surfaces on both sides, a flat surface of the lenticular lens sheet and the light A rear projection screen including a light absorbing layer, a light diffusing layer, and an optical coupling layer existing between one surface of the transmitting member. 2. A lenticular lens sheet having a lenticular lens array on one surface and a flat surface on the other surface; a light absorbing layer adjacent to the flat surface of the lenticular lens sheet; An optical coupling layer adjacent to the optical coupling layer, a light diffusion layer adjacent to the optical coupling layer, and a light transmission member having flat surfaces on both sides adjacent to the light diffusion layer, the surface having the light absorption layer and the light A rear projection screen in which a surface having a diffusion layer is optically coupled. 3. A lenticular lens sheet having a lenticular lens array on the projection side and a flat surface on the other side, in order from the projection side to the side viewing the screen, a light diffusion layer, a light absorption layer, A rear projection screen, comprising an optical coupling layer and a light transmitting member having flat surfaces on both sides, wherein the surface on which the light absorbing layer is formed and the light transmitting member are optically coupled. 4. The lenticular lens sheet has a thickness substantially equal to a focal length of a lens of the lenticular lens array, and a flat surface of the lenticular lens sheet on which the light absorbing layer is formed in a light opaque region. 3. The rear projection screen according to claim 2, wherein a surface of the light diffusion layer formed on the projection side surface of the light transmitting member is optically coupled with a transparent adhesive. 5. The rear projection screen according to claim 4, wherein the arrangement pitch of the lenses of the lenticular lens array is 0.2 mm or less. 6. The light transmitting member has a thickness of 1 mm or more and 5 m or more.
The rear projection screen according to claim 4, wherein m is equal to or less than m. 7. The rear projection screen according to claim 4, wherein a diffusion material that isotropically diffuses light is dispersed in the light diffusion layer. 8. The lens array pitch of the lenticular lens array is 0.2 mm or less, the thickness of the light transmitting member is 1 mm or more and 5 mm or less, and the light diffusion layer diffuses light isotropically. 5. The rear projection screen according to claim 4, wherein the diffusing material is dispersed. 9. The lenticular lens sheet has a thickness substantially equal to a focal length of a lens of the lenticular lens array, and a flat surface of the lenticular lens sheet on which the light absorbing layer is formed in a light opaque region. 4. The rear projection screen according to claim 3, wherein the surface of the light diffusion layer formed on the projection side surface of the light transmitting member is optically coupled with a transparent adhesive. 10. The rear projection screen according to claim 9, wherein an arrangement pitch of the lenses of the lenticular lens array is 0.2 mm or less. 11. The light transmitting member has a thickness of 1 mm or more and 5 mm or more.
10 mm or less. 12. The rear projection screen according to claim 9, wherein a diffusion material that isotropically diffuses light is dispersed in the light diffusion layer. 13. The lenticular lens array has a lens array pitch of 0.2 mm or less, the light transmitting member has a thickness of 1 mm or more and 5 mm or less, and the light diffusing layer diffuses light isotropically. 10. The rear projection screen according to claim 9, wherein the diffusing material is dispersed. 14. A step of forming a lenticular lens on one surface and forming a lenticular lens sheet having a flat surface and a thickness substantially equal to the focal length of the lenticular lens on the other surface by curing an ultraviolet curable resin; Forming a light-absorbing layer in a light-impermeable region on a flat surface of the transparent lenticular lens sheet by a lift-off method using an ultraviolet curable resin; and The method for manufacturing a rear projection screen according to claim 4, further comprising a step of bonding the surface having the light diffusion layer with a transparent adhesive. 15. The method according to claim 4, wherein the transparent adhesive is an acrylic transparent adhesive. 16. The method according to claim 4, wherein the light transmitting member having the light diffusing layer is formed by a two-layer extrusion molding method. 17. A step of forming a lenticular lens on one surface and forming a lenticular lens sheet having a flat surface and a thickness substantially equal to the focal length of the lenticular lens by curing an ultraviolet curing resin; A step of providing a light diffusion layer in which a diffusion material that diffuses light isotropically dispersed on the flat surface of the transparent lenticular lens sheet; a light absorption layer in a light impermeable region above the light diffusion layer; The back surface according to claim 9, further comprising: a step of forming by a lift-off method used; and a step of bonding a surface of the lenticular lens sheet having a light absorbing layer and a surface of the light transmitting member having a light diffusion layer with a transparent adhesive. Manufacturing method of projection screen. 18. The method according to claim 9, wherein the transparent adhesive is an acrylic transparent adhesive. 19. The method of manufacturing a rear projection screen according to claim 9, wherein the light transmitting member having the light diffusing layer is formed by a two-layer extrusion molding method. 20. A lenticular lens array, a light transmitting member, a light absorbing layer, a light diffusing layer, and a material having substantially the same refractive index as the optical coupling layer.
Or a rear projection screen according to 3. 21. A rear projection type image display device using the rear projection screen according to claim 1. 22. A rear projection type image display apparatus using a liquid crystal panel using the rear projection screen according to claim 1, as an image source.