WO1997017633A1

WO1997017633A1 - Transmission-type screen, method of producing the same and backsurface projection image display using the same screen

Info

Publication number: WO1997017633A1
Application number: PCT/JP1995/002300
Authority: WO
Inventors: Koji Hirata; Takahiko Yoshida; Shigeru Inaoka
Original assignee: Hitachi, Ltd.
Priority date: 1995-11-10
Filing date: 1995-11-10
Publication date: 1997-05-15
Also published as: JP3689430B2

Abstract

A transmission-type screen comprising a plurality of screen sheets, wherein a plurality of lenses for collecting light are arranged in succession on a plane of image light incidence of at least one screen sheet, the lenses are focused inside the sheet, and a light-absorbing layer is provided on a region where the image light near the focal point does not pass through, in order to decrease multiple reflection and reflection of external light among the screen sheets and to improve focusing characteristics and contrast of the image. Moreover, the center of the region where the image light passes through is nearly brought into agreement with the optical axis of the lens provided on the plane of image light incidence. A predetermined decentering quantity d is imparted to the end portions, and a Fresnel lens is provided on the outgoing plane.

Description

Specification

TECHNICAL FIELD The present invention relates to a transmission screen, a method of manufacturing the same, and a rear projection type image display apparatus using the same.

The present invention relates to a transmission screen, a method of manufacturing the same, and a rear projection image display device using the same. Background art

Projection type cathode ray tube as image source ゃ Rear projection type image display such as a rear projection type television receiver that enlarges the image displayed on a liquid crystal display device etc. with a projection lens and projects it from the back onto a transmission type screen In recent years, devices have been remarkably improved in image quality and have a powerful large screen that allows them to enjoy a sense of presence.

In this rear-projection image display device, when a projection type cathode-ray tube is used as an image source, the three primary colors of red, green, and blue have been conventionally used in order to sufficiently increase the brightness of the screen on the screen. It is common practice to combine three primary color images on a screen by combining a projection tube and a projection lens.

FIG. 19 is a plan view showing an outline when the projection optical system is developed on a horizontal plane. In the figure, 16, 17, and 18 are blue, green, and red projection CRTs, 19 is the corresponding projection lens, and 20, 21, and 22 are blue, 綠, and red, respectively. This is the optical axis of the image light. As shown in Fig. 20, the optical system of the rear projection type image display device Most mirrors exist, but this mirror is omitted in Fig. 19.

FIG. 20 is a vertical sectional view showing a main part of the rear projection type image display device. The image displayed on the surface of the projection type cathode ray tube 28 is magnified by the projection lens 26, and is projected from the back onto the transmission screen 24 via the optical path bending mirror 23. ing.

In a rear projection type image display apparatus having this configuration, conventionally, for example, as described in Japanese Patent Application Laid-Open No. 56-117272, a screen sheet provided with a Fresnel lens on one side (see, for example, Hereafter, this is referred to as a Fresnel lens sheet.) And a screen sheet provided with a lenticular lens on both sides (hereinafter referred to as a lenticular lens sheet). Had been. Further, as a screen which discloses specific technical means for realizing diffusion of image light in the vertical direction of the screen, for example, Japanese Patent Application Laid-Open No. 58-192022 discloses a screen. In addition, a two-part transmission screen, which is a combination of a Fresnel lens sheet and a lenticular lens sheet in which fine particles that scatter light are dispersed, is generally used.

Hereinafter, these will be described.

FIG. 21 is a perspective view showing the main components of a transmission screen as an example of the prior art. In FIG. 21, reference numeral 38 denotes a transmission screen, which is composed of two lens sheets, a Fresnel lens sheet 36 and a lenticular lens sheet 7. The base material of each sheet is made of a transparent thermoplastic resin. Of these, fine particles of the light diffusing material 37 for scattering light are dispersed in the base material of the lenticular lens sheet.

The image light incident surface 35 of the Fresnel lens sheet 36 is flat. The exit surface of the Fresnel lens sheet 36 for the image light has a Fresnel convex lens shape 3. Reference numeral 6 denotes an image light incident surface of the lenticular lens sheet 7, and a lenticular lens (hereinafter, referred to as a “second lenticular lens”) having a longitudinal direction perpendicular to the screen is provided in the horizontal direction of the screen. It has a shape arranged continuously. Reference numeral 9 denotes an emission surface of the image light of the lenticular lens sheet 7, and a lenticular lens (hereinafter, referred to as a “third lenticular lens”) having a longitudinal direction perpendicular to the screen screen, It has a shape that is substantially opposed to the two lenticular lenses and is continuously arranged in the horizontal direction of the screen. The third lenticular-lens interface is provided with a convex protrusion 60 at the boundary between the lenses, and a light absorbing layer (black stripe) .8 having a finite width is provided thereon. It is designed to prevent image quality degradation due to the influence of external light such as sunlight and sunlight, and in particular, a decrease in contrast performance.

In the transmission screen shown in FIG. 21, the light flux emitted from each point of the display image on the projection screen of the Braun tube passes through a projection lens (neither of which is shown) to form a Fresnel lens sheet 36. Incident on the light incident surface 35 of the light source. Then, this incident light beam is converted into a substantially parallel light beam by the Fresnel convex lens 3 on the light exit surface of the Fresnel lens sheet 36, and enters the lenticular lens sheet 7. The light beam incident on the lenticular lens sheet 7 is directed to the focal point near the third lenticular lens surface on the light emitting surface 9 by the second lenticular lens on the incident surface 6, and diffuses from the focal point in the horizontal direction of the screen. At the same time, the light is diffused in the vertical and horizontal directions of the screen by the fine particles of the light diffusing material 37 dispersed in the base material and emitted to the viewer side. That is, the light passing through the lenticular lens sheet 7 is diffused in the horizontal direction of the screen depending on the shape of the entrance surface 6 of the lenticular lens-lens sheet 7 and diffused in the vertical direction of the screen by a light diffusing material 3 7. Is performed only by the action of In addition, in order to realize diffusion of image light in the vertical direction of the screen, for example, as described in Japanese Patent Application Laid-Open No. 58-93043, the image light is screened by a lens function. A transmission screen having a two-piece configuration is used in which a Fresnel lens sheet having a function of vertically diffusing and a lenticular lens sheet in which light scattering fine particles are dispersed are combined. Hereinafter, this will be described.

FIG. 22 is a perspective view showing a main part of a configuration of another embodiment of the transmission screen according to the prior art in the prior art. In FIG. 22, reference numeral 40 denotes a transmission screen, which is composed of two screen sheets, a Fresnel lens sheet 39 and a lenticular lens sheet 7. Each base material uses the same transparent thermoplastic resin as the structure shown in FIG.

In this example, a lenticular lens 38 (hereinafter referred to as a first lenticular lens) having a horizontal direction as a longitudinal direction is provided on the image light incident surface of the Fresnel lens sheet 39 in this example. The shape is continuous in the direction. Other configurations are the same as those in FIG.

In the transmission screen shown in FIG. 22, the first lenticular lens whose longitudinal direction is the horizontal direction of the screen screen is provided on the entrance surface of the Fresnel lens sheet 39, so that the incident light flux is The first lenticular lens provides diffusion characteristics in the vertical direction of the screen. Thereafter, the diffusion characteristics in the vertical direction of the screen are also provided by the fine particles of the light diffusing material 37 dispersed in the base material of the lenticular lens sheet 7.

The pitch of the first lenticular lens 38 is usually designed to be smaller than the pitch of the scanning lines of the projected image or the pitch of the pixels, and is about 0.1 mm at present. Thus, when an incident light beam is incident from the first lenticular lens surface 38 of the incident surface, each incident light beam will have the same scan line or the same image. Even if it is elementary, the angle of incidence differs depending on the incident position, so it will bend at a different angle and diffuse in the vertical direction of the screen. That is, the light passing through the transmission screen is diffused in the horizontal direction of the screen depending on the shape of the incident surface of the lenticular lens sheet 7, and the diffusion in the vertical direction is based on the action of the light diffusing material 37 and the screen. This is performed by the action of the first lenticular lens 38 whose longitudinal direction is the horizontal direction of the lean screen. In order to further increase the diffusion in the vertical direction, it is necessary to increase the amount of the light diffusing material 37 dispersed in the base material. As a solution to this, as shown in FIG. 23, the light diffusing material 37 dispersed in the base material of the lenticular lens sheet 7 is collected near the surface of the third lenticular lens. Transmission-type screens that prevent a decrease in focus performance and obtain a wide diffusion angle have also been proposed.

In the conventional transmission screen described above, as described above, a projection 60 is provided at the boundary between the third lens and the lens, and a light absorbing layer (black stripe) having a limited width is provided thereon. The configuration provided with 6 reduces reflection when external light such as room illumination light or sunlight enters the screen surface.

However, in a generally used transmission screen, the finite width of the light absorbing layer (black stripe) 6 accounts for only about 40% of the entire screen. The presence of extraneous light reflected on the surface of the third lenticular lens made it impossible to completely suppress the decrease in contrast. Furthermore, the image light rays are reflected multiple times on the entrance surface of the lenticular lens sheet 7 and the exit surfaces of the Fresnel lens sheet 36 and the Fresnel lens sheet 39, which not only reduces the contrast but also reduces the focus performance. The decline was also occurring.

In the conventional transmission screen shown in FIG. The image light beam is diffused and incident on the Fresnel lens provided on the viewing side by the action of a horizontally long lenticular lens provided on the image light incident surface of the lens sheet 39 for diffusing light in the direction perpendicular to the screen. This increases the angle of incidence on the Fresnel lens and increases the return loss. At the upper and lower ends of the screen, the incident angle to the Fresnel lens is particularly large, so that the transmittance of the image light is reduced and the brightness around the screen is reduced.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the prior art, and reduce the contrast of an image, the focus performance, and the brightness of the peripheral portion of a screen. Another object of the present invention is to provide a rear projection type image display device constituted by the method and the manufacturing method thereof. Disclosure of the invention

The present invention provides a means for preventing a decrease in contrast performance and focus performance, which is the first problem, by using at least one screen sheet constituting the transmission screen of the present invention. A plurality of lenses having a function of condensing image light are continuously arranged on the image source side (incident surface side) of the sheet, and the focal points of the individual lenses are present inside the screen. In the vicinity, a light absorbing part will be provided in a region where the image light does not pass. Further, an optical axis of a lens provided on the image source side (incident surface side) of the screen sheet and having a function of condensing image light, and a center of an area inside the screen sheet through which the image light passes. Are substantially matched at the center of the screen, and have a predetermined decentering amount d toward the edge of the screen, and the decentering amount d is gradually increased.

Next, as a solution to the above-mentioned second problem of lowering the brightness of the peripheral portion, the screen sheet is divided into a plurality of portions, each of which is refracted as a base material. A lens having a different ratio is used, and a lens for converting the image light beam into substantially parallel light is provided in a region of the lenticular lens substrate through which the image light beam passes.

Further, as a manufacturing method for easily obtaining the transmission type screen according to the present invention, the above-mentioned screen sheet is manufactured by being divided into a plurality of parts. That is, the first portion has a plurality of lenses having an action of condensing image light continuously arranged on one surface, and a notch portion is provided on the opposing surface near the focal point of each of the lenses, Further, a flat portion is provided in an area where the image light does not pass, and a light absorbing layer is printed or applied on the flat portion. The surface of the first portion (substrate) thus obtained is cured by ultraviolet light. A Fresnel lens is formed with a resin or the like, the second part is obtained, and finally the Fresnel lens sheet of the present invention is obtained.

Further, the rear projection type image display device of the present invention includes the above-mentioned transmission type screen according to the present invention, and combines an image source and a projection lens with a coupler to form a lens group constituting a projection lens. The lens located closest to the image source is a concave lens with a convex surface on the image source side and a concave surface on the screen side, and the liquid refrigerant is placed in the space between the image source and the concave lens in the coupler. The structure will be used in combination with the conventional contrast improvement technology of encapsulation.

In a rear-projection image display apparatus using a transmission screen having the above configuration, light emitted from an image generation source such as a projection CRT enters a transmission screen via a projection lens. The screen sheet arranged on the image generation source side of the transmission screen is composed of two types of base materials having different refractive indexes, and its entrance surface has a plurality of lenses that have the function of condensing the image light. Pieces are arranged continuously. For this reason, the image light beam is focused on the focal point of each lens existing inside the screen. Therefore, a light absorbing layer is provided in the area inside the screen where the image light does not pass, By absorbing the multiple reflection light and the like generated between the external light and the screen sheet incident on the screen from above through the light absorption layer, the contrast and the reduction in the performance of the thin film are greatly reduced.

Further, a lens having an action of converting image light into substantially parallel light is provided near the focal point of the lens provided on the incident surface. As a result, the image light rays become almost parallel light and enter the Fresnel lens provided on the viewing side, so that the angle of incidence on the Fresnel lens can be reduced, and the reflection loss can be reduced, resulting in lower brightness of the screen. do not do.

By providing Fresnel lenses on the opposing surfaces, the image light that has passed through the screen sheet (hereinafter referred to as the Fresnel lens sheet) becomes almost parallel light. Then, the light enters a lenticular lens sheet arranged on the image viewing side of the transmission screen, and a lenticular lens provided on the entrance and exit surfaces of the lenticular lens (perpendicular to the screen surface). The diffusion in the horizontal direction of the screen is controlled by the shape of a lenticular lens whose direction is the longitudinal direction. Also in the present invention, in order to temporarily collect the image light on the emission surface of the lenticular lens sheet, a projection 60 is provided in a region of the emission surface through which the image light does not pass, and the light absorption layer 8 ( Black stripes). For this reason, even if external light such as illumination light is incident on the exit surface of the transmission screen by combining with the light absorption layer provided on the above-mentioned Fresnel lens sheet, some of the incident light Since the light is absorbed in the light absorbing layer and is not reflected, the contrast when viewing an image in a bright place is further improved. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view showing a main part of a transmission screen as a first embodiment of the present invention. FIG. 2 is a perspective view showing a main part of a transmission screen as a second embodiment of the present invention.

FIG. 3 is a perspective view showing a main part of a transmission screen as a third embodiment of the present invention.

FIG. 4 is a vertical sectional view of the screen showing a main part of the Fresnel lens sheet 2 near the center of the screen in FIG.

FIG. 5 is a plan view schematically showing a vertical cross section of a projection optical system of a general rear projection type image display device, omitting an optical path turning mirror.

FIG. 6 is a vertical sectional view of a screen showing a main part of the Fresnel lens sheet 2 in FIG. 1, and is an explanatory diagram of lens shape data.

FIG. 7 is an explanatory diagram for explaining the definition of the lens shape.

FIG. 8 is an explanatory diagram for explaining a method of manufacturing a transmission screen of the present invention.

FIG. 9 is an explanatory diagram for explaining a method of manufacturing a transmission screen according to the present invention.

FIG. 10 is an explanatory diagram for explaining a method of manufacturing a transmission screen according to the present invention.

FIG. 11 is an explanatory diagram for explaining a method of manufacturing a transmission screen of the present invention.

FIG. 12 is an explanatory diagram for explaining a method of manufacturing a transmission screen according to the present invention.

FIG. 13 is an explanatory diagram for explaining a method of manufacturing a transmission screen of the present invention.

FIG. 14 is an explanatory diagram for explaining a method of manufacturing a transmission screen of the present invention. FIG. 15 is a vertical cross-sectional view of the Fresnel lens sheet 2 of the present invention, showing a main portion near the center of the screen.

FIG. 16 is a vertical sectional view of the Fresnel lens sheet 2 according to the present invention, showing a main portion near the center of the screen.

FIG. 17 is a vertical cross-sectional view of the Fresnel lens sheet 2 of the present invention, showing a main portion near the center of the screen.

FIG. 18 is a vertical cross-sectional view of the Fresnel lens sheet 2 of the present invention showing a main part near the center of the screen.

FIG. 19 is a plan view showing an outline when a projection optical system of a general rear projection type surface image display device is developed on a horizontal plane.

FIG. 20 is a schematic plan view of a vertical cross section showing a projection optical system of a general rear projection type image display device.

FIG. 21 is a perspective view showing a main part of an example of a transmission screen according to the prior art.

FIG. 22 is a perspective view showing a main part of another example of the transmission screen according to the prior art.

FIG. 23 is a perspective view showing a main part of another example of the transmission screen according to the prior art. BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described with reference to the drawings. First, a first embodiment of the present invention will be described.

FIG. 1 is a perspective view showing a main part of a transmission screen as a first embodiment of the present invention.

In FIG. 1, reference numeral 10 denotes a transmission screen, which is constituted by a Fresnel lens sheet 2. a lenticular lens sheet 7. Fresnel lens Sheet 2 and lenticular lens sheet 7 are fixed to each other at their ends (not shown). The Fresnel lens sheet 2 includes a lenticular lens substrate 46 and a Fresnel lens substrate 52. Lenticular lens base material 46 Refractive index n of 6. Is smaller than the refractive index η of the Fresnel lens substrate 52. The base material of the lenticular lens sheet 7 is also a substantially transparent thermoplastic resin material.

In this embodiment, the light incident surface of the Fresnel lens sheet 2 is formed by connecting a horizontally long lenticular lens 1 (hereinafter, referred to as a first lenticular lens) whose longitudinal direction is the screen screen in the screen vertical direction. The shape is arranged side by side. The focal points FF ₂ and F ₃ of the first lenticular lens are located inside the Fresnel lens sheet 2, and near the focal points F 1, F ₂ and F 3, almost once the focused image light rays are emitted. A horizontally long lenticular lens is provided as a lens element 5 for converting into a parallel light beam. Further, in a region through which the image light beam does not pass, a horizontally long light absorbing layer 4 whose longitudinal direction is the horizontal direction of the screen screen is provided. The emitting surface of the Fresnel lens sheet 2 for image light is a Fresnel convex lens 3. The light-incident surface of the lenticular lens lens 7 is composed of a vertically long lenticular lens 6 (hereinafter referred to as a second lenticular lens) whose longitudinal direction is perpendicular to the screen screen. It has a shape. Similarly, a vertical lenticular lens 9 (hereinafter, referred to as a third lenticular lens) having a longitudinal direction perpendicular to the screen screen is provided on the exit surface of the image light with a second lenticular lens 6 on the incident surface. It is arranged so as to face the screen and to be continuously arranged in the horizontal direction of the screen. Further, a protrusion 60 is provided at a boundary between the third lenticular lenses, and a vertically long light absorbing layer 8 having a finite width is provided thereon.

FIG. 4 shows the Fresnel lens in the first embodiment of the present invention shown in FIG. FIG. 6 is a vertical cross-sectional view of a main part near the center of the screen of the second sheet in the screen vertical direction. Image light rays from an image source (not shown) are converted into finely divided light beams by a first lenticular lens (horizontally elongated lenticular lens) provided on the incident surface of the Fresnel lens sheet 2, and each lenticular light is emitted. The lens focuses on the focal point F (F ,, F :, F ,, F "„ in the figure) that once exists inside the Fresnel lens sheet 2, and the individual luminous flux is focused most near the focal point State.

Since these luminous fluxes are continuously arranged in the vertical direction of the screen, the region where the image light rays existing between the adjacent focal points do not pass is similarly arranged in the vertical direction of the screen. Become. If the horizontally long light absorbing layer 4 is provided in the area where this image light does not pass, the outside light 43 such as indoor illumination light and sunlight, the Fresnel lens sheet emission surface and the lenticular sheet will be provided without affecting the image light. Since it absorbs multiple reflections generated at the entrance surface (not shown), it is possible to significantly reduce contrast and focus performance.

In the vicinity of each of the focal points F 1, F _z , and F 1 of the first lenticular lens, a lens element 5 for converting the once converged image light beam into a substantially parallel light beam is provided on the image viewing side. Is provided with a horizontally long wrench lens having a concave shape. By this lens action, the image light rays enter the Fresnel lens provided on the viewing side almost in parallel, so that the angle of incidence on the Fresnel lens can be reduced and the reflection loss can be reduced, thus lowering the brightness of the screen. Never. In this embodiment, since the refractive index η of the lenticular lens substrate 46 is smaller than the refractive index η of the lenticular lens substrate 52, the shape of the lens element 5 is concave toward the viewing side.

In the present embodiment, the optical axis of the first lenticular lens and the center of the area through which the image light rays inside the screen sheet pass are: The decentering amount d is set to be substantially the same, and has a predetermined decentering amount d toward the edge of the screen, and the decentering amount d gradually increases.

Hereinafter, the optimal decenter amount d will be described with reference to FIGS. 5 and 6. FIG. 5 is a plan view schematically showing a vertical cross section of a projection optical system of a general rear projection type image display device without a folded mirror. FIG. 6 is a schematic cross-sectional view in the vertical direction of the screen showing a main part of the Fresnel lens sheet 2 in the first embodiment of the present invention shown in FIG. (Partially omitted). In FIG. 5, when the distance from the tip of the projection lens to the transmission screen is (projection distance) L, the screen of the image light ray at the evaluation point P. The incident angle 0, is θο = t an ” ^l (D ₁ Lo) …… (Equation 1)

Required by Further, as shown in FIG. 6, if the refractive index of the lenticular lens substrate 46 of the Fresnel lens sheet 2 constituting the transmission screen is η, ', the angle 0

0o '= sin ~' (sin (t an-^ D! / Lo) / n.)) …… (Equation 2)

The image light flux entering the Fresnel lens sheet 2 from an image source (not shown) enters the Fresnel lens sheet 2 almost vertically at the center of the screen. For this reason, as shown in FIG. 6, the image light flux 42-1 is condensed on the focal point F, which is a distance L away from the lens surface of the lenticular lens 1 provided on the incident surface. However, the angle S, at which the image light flux enters the Fresnel lens sheet 2 gradually increases from the center of the screen to the middle area and further to the lower end. For example, in the middle area of the screen, the image light flux 4 2-2 becomes the lenticular lens 1. However, even if the light is condensed by the optical axis, the light is not condensed at the focal point F on the optical axis 1 されず but is condensed at a distance d from the optical axis 1 だけ. Therefore, the center position of the opening (light passage portion 5) formed by the light absorbing layer 4 is separated from the optical axis 1 by distance d, (decenter amount d,). Similarly, at the lower end of the surface, desired performance can be obtained if the center position of the opening (light passing portion 5) formed by the horizontally long light absorbing layer 4 is separated from the optical axis 11 'by a distance d, (a decenter amount d :). Can be.

The decentering amount d, is derived from equations 1 and 2 d = L tan (sin "'(sin (ta n' ^ D. / Lo) Z n 0)> ...... ( Equation 3)

Can be obtained by

Here, L is the focal length of the first lenticular lens.

Tables 1, 3, and 5 show examples of the cross-sectional shape (lens shape) of the horizontally long lenticular lens according to the embodiment of the present invention in the direction perpendicular to the surface. Table 2 shows the optimum decenter amount d at the distance from the center of the screen corresponding to the embodiment shown in Table 1. Similarly, Table 4 corresponds to Table 3 and Table 6 is the decentering quantity d corresponding to Table 5.

Next, how to read lens shape data will be described based on Tables 1 and 2. 5 Table 1

The lens shape of the horizontally long lenticular lens provided on the entrance surface has a radius of curvature of 0.9345 mm, a distance of 1 mm on the optical axis from the entrance surface to the focal point F is 2.5133.6 mm, It is shown that the refractive index n, of the base material with respect to light having a wavelength of 545 nm, is 1.540. Also, it can be seen that the effective diameter of the horizontally long wrench lens is 0.14 mm. At this time, the diameter of the light beam condensed at the focal point F is calculated to be 0.006 mm, but the manufacturing error due to the manufacturing method described later and the light beam when the image light beam enters the upper and lower ends of the screen will be described. In consideration of the spread, the opening (light passing portion 5) of the horizontally long light absorbing layer 4 is set to 0.05 mm. At this time, the width of the light passing portion 5 is 0.05 mm, while the lens pitch of the horizontally long lenticular lens is 0.14 mm, so that the ratio of the light absorbing layer is about 65%. . In the present embodiment, the refractive index η of the substrate from the horizontally long light absorbing layer 4 to the Fresnel lens surface with respect to light having a wavelength of 545 nm is also 1.540.

If the sign of the radius of curvature is positive, it indicates that the center of curvature of the lens surface is located in a direction from the optical axis toward Γ from the lens surface. The aspheric coefficients CC and AE are coefficients when the lens surface shape is expressed by the following equation. r ² / RD

Zhi) =

+-[1 + CC] ■ / RD ²

+ AE .r ⁴ + AF .Γ ^β + Α (τ · Γ ^β + ΑΗ · Hiro ¹ (Equation 4) Where Z is the height of the lens surface when the direction from 光 of the optical axis toward Γ is taken as the Z axis and the radial direction of the lens is taken as the r axis, as shown in FIG. Where r is the radial distance and R is the radius of curvature. Therefore, if the coefficients of CC, AE, AF, AG, and AH are given, the height of the lens surface, that is, the shape, is determined according to the above equation.

This is how to read the data shown in Table 1. The reading of the data of the other examples shown in Tables 3 to 5 is the same. table 1

Table 2 shows that, at the periphery of the screen, the image light flux from the image source (not shown) 4 2-2 and 4 2-3 force is incident on the Fresnel lens sheet 2. In the lenticular lens shape corresponding to the illustrated embodiment, an optimum decenter amount d at a distance from the screen center is shown. For example, the decenter amount d at a distance of 45.6 mm from the center of the screen in the vertical direction of the screen is 0.5344.22 mm. Table 3

Included RD 0.940 6 Radiation CC 6. 0755949 Surface AE 0.10655055 Exist δ radius P / 2 (mm) 0.085

2.53 13 Orifu (i = 545nm) 1.540 Ratio of light absorbing layer) 68 Table

Si (mm) decentering from screen center d (mm)

0 0. 0

97.1 0.10939

194.3 0.2 1820

29 1.4 0. 32585

388.5 0.43 184

485.6 0.53572 Table 5

Enter RD 0.99 121 Fire CC -0.997706 Surface AE

Effective radius P / 2 (mm) 0.1766 To Xiao et al. Ιϋ! (■) 2.500 lttM $ (i = 545nm) 1.540 Ratio of light absorption layer) 77.3 Table 6

S departure from screen center (■) Decenter amount d (mm)

0 0. 0

97.1 0.10820

194.3 0.2 1 580

29 1.4 0. 32210

388. 5 0. 42689

485.6 0.52937 As shown in Tables 1, 3 and 5 as examples of the present invention, the case where the refractive index n of the lenticular lens substrate is smaller than the refractive index η of the Fresnel lens substrate is shown. In addition, the refractive index of the base materials may be different, or the lens surface shape of the bonding surface of each base material may be the image collected by the first lenticular lens on the bonding surface of each base material. Needless to say, the present invention also includes a configuration having a lens function of converting a light beam into a substantially parallel light beam.

FIG. 2 is a perspective view showing a main part of a transmission screen as a second embodiment of the present invention. The difference from the first embodiment shown in FIG. 1 is that the light incident surface of the Fresnel lens sheet 2 faces the vertical lenticular lens 1 whose longitudinal direction is in the vertical direction of the screen in this embodiment. The point is that they are arranged continuously in the horizontal direction.

For this reason, the focal points F1, F2, and F3 of the lenticular lenses also exist inside the Fresnel lens sheet 2 as in the first embodiment. A vertically long light absorbing layer 13 whose longitudinal direction is perpendicular to the screen screen is provided in a portion where the image light rays near the focal point do not pass.

FIG. 3 is a perspective view showing a main part of a transmission screen as a third embodiment of the present invention. The difference from the first embodiment shown in FIG. 1 is that the transmission screen has a three-piece structure. In this embodiment, a Fresnel lens sheet 36 is arranged at a position closest to a video source (not shown), and the Fresnel lens 3 provided on the exit surface converts the video rays into substantially parallel rays. It is incident on the horizontal lenticular sheet 61. The image luminous flux is once condensed at the focal point F of each lens by the horizontal lenticular lens 1 provided on the entrance surface of the horizontal lenticular sheet 61, and diffuses from the matted emission surface. In the vicinity of the focal point F of the horizontally elongated lenticular lens 1 inside the horizontally elongated wrench sheet 6 1, as in the first embodiment, horizontally elongated light absorption is performed. Layer 4 is provided. The lenticular sheet 7 has the same function as that of the first embodiment, and the description is omitted here.

In the present embodiment, the case where the exit surface of the horizontally long lenticular sheet 61 is subjected to a matting process has been described. However, even if the entrance surface is a vertically long lenticular sheet having a vertically elongated lenticular lens, the case where the emission is flat Needless to say, this is substantially included in the present invention.

The method of manufacturing the Fresnel lens sheet and the horizontally long lenticular sheet shown in the examples of the present invention will be described below with reference to FIGS. 8 to _14c . A model of a molding machine for manufacturing The sheet base material 46 extruded from the extruder 43 is used to transfer a lenticular lens shape provided on the image light incident surface to a transfer drum 44, and a transfer drum 44 for printing a light absorbing layer. The desired shape is transferred by the transfer drum 441-1 for transferring the flat part and the notched part. Then, the desired light absorbing layer 4 is obtained on the surface of the flat part by the light absorbing layer printing drum 45.

9 and 10 show the cross-sectional shape of the sheet base material 46 after the sheet base material 46 has been formed by the transfer drums 441-1 and 441-2, respectively. FIG. 9 shows an embodiment in which the cutout portion 48 provided on the surface on which the light absorbing layer is printed has a U-shape. A lenticular lens is formed on the image light incident surface. FIG. 10 shows an embodiment in which the shape 50 of the cutout portion provided on the surface on which the light absorbing layer 4 is printed has a V-shape.

The cross-sectional shape of the sheet base material 46 after the desired light absorption layer is printed on the flat surface by the light absorption layer printing drum 45 shown in FIG. 8 is shown in FIGS. Figure 12 shows. FIG. 11 corresponds to FIG. 9, and FIG. 12 corresponds to FIG.

After printing the light absorbing layer 4, the sheet base material 46 is cut into desired dimensions, Proceed to the final step of forming the Fresnel lens. As a means for forming the Fresnel lens 3 on the sheet substrate 46 after the light absorbing layer 4 is printed, a 2P method using an ultraviolet curable resin for the substrate 52 is generally used.

FIGS. 13 and 14 show cross-sectional shapes of the embodiment of the present invention in which the Fresnel lens 3 is formed on the sheet base material 46 after the light absorbing layer 4 is printed. FIG. 13 corresponds to FIG. 11, and FIG. 14 corresponds to FIG.

FIGS. 15 and 16 show ray tracing results when an image light beam enters the embodiment of the present invention shown in FIGS. 13 and 14. FIG. In this embodiment, the refractive index n0 of the lenticular lens base material 46 is larger than the refractive index η of the Fresnel lens base material 52, and the bonding surface of each base material is the first lenticular lens base material. This figure shows the lens shape of the cemented surface and the results of ray tracing when the focal position of the lens is closer to the image light incident surface side.

FIG. 17 and FIG. 18 also show other lens shapes that can be taken by the joint surface under the same conditions, and the results of ray tracing. It has a concave lens shape on the viewing side, and is an optimal lens shape for the manufacturing method described above.

The method of manufacturing the Fresnel lens sheet as an embodiment of the present invention has been described above. In addition, for example, a flat mat surface or the like may be formed on the sheet base material 46 after the light absorbing layer is printed. The present invention includes a configuration in which a shape other than the Fresnel lens is formed. As described above, according to the present invention, a lens having a light condensing function is continuously provided on at least the image light incident surface of at least one screen sheet constituting the transmission screen. Since the light absorbing layer is provided in the area where the image light does not pass inside the lean sheet, unnecessary reflection light is reduced by absorbing multiple reflection between screen sheets and external light, etc., and the contrast of the image is improved. It is possible to reduce the deterioration and the focus characteristic. Further, a lens having an action of converting the image light into almost parallel light is provided near the focal point of the lens provided on the image light incident surface. As a result, the image light rays become almost parallel rays and enter the Fresnel lens provided on the viewing side, so that the angle of incidence on the Fresnel lens can be reduced and the reflection loss can be reduced, so that the brightness of the screen does not decrease. .

Further, since the Fresnel lens surface is formed after printing the light absorbing layer, the transmission screen having the light absorbing layer can be manufactured very easily. Industrial applicability

INDUSTRIAL APPLICABILITY As described above, the present invention is useful in the configuration of a projection-type image display device and the transmission-type screen used for the same, and in manufacturing the same, and in particular, reduces image contrast and focus characteristics. It is suitable for use as a transmission screen technology for preventing a decrease in screen brightness.

Claims

The scope of the claims

1. In a transmissive screen that transmits image light incident from the image source side and emits it to the image viewing side,

At least one of the screen sheets forming the screen has a configuration in which a plurality of base materials having different refractive indices are joined, and the screen surface on the image source side condenses the image light. The focal point of each lens is located near the joint surface of the base material, and the joint surface has a lens shape that converts the focused image light into substantially parallel light. A light absorbing layer is provided in an area where the image light near the focal point of the lens provided on the screen surface on the image generation source side does not pass, and a Fresnel lens is provided on the screen surface on the image viewing side. A transmission screen characterized by its configuration.

2. The transmission screen according to claim 1, wherein the screen surface on the image source side of the screen sheet is formed by continuously arranging a plurality of lenses for condensing image light. The focal point of each lens is located near the bonding surface of the base material, and the bonding surface has a lens shape for converting the focused image light into substantially parallel light, and the screen on the image generation source side. A light absorbing layer is provided in a region near the focal point of the lens provided on the surface where the image light does not pass, in parallel with the screen incident surface, and a Fresnel lens is provided on the screen surface on the image viewing side. A transmission screen characterized by a configuration.

3. The transmission-type screen according to claim 1, wherein the screen sheet includes a plurality of screens each having a screen-source-side screen surface whose longitudinal direction is the horizontal direction of the screen screen. It has a shape in which lenticular lenses are continuously arranged in the vertical direction of the screen, and the focal point of each lens is located near the bonding surface of the base material, and the bonding surface converts the condensed image light into substantially parallel light. A light absorbing layer is provided in an area where the image light near the focal point of the lens provided on the screen surface on the image source side does not pass through, and A transmission screen characterized by having a Fresnel lens on the side of the screen.

4. In a transmission screen that transmits image light incident from the image source side and emits it to the image viewing side,

(5) At least one screen of the screen sheet forming the screen has a screen surface on the image source side which is formed by arranging a plurality of lenses for condensing image light in a continuous gun, The screen sheet has a configuration in which a plurality of base materials having different refractive indices are joined to each other. The refractive index of the base material located on the image generation source side is n ·, and the refractive index of the base material located on the image viewing side is n. Where η is the rate

0 η,> η,

The focal point of each lens provided on the screen surface on the image source side is located closer to the image source than the joint surface of the base material, and the joint surface is concave on the image viewing side. A light-absorbing layer provided substantially in parallel with the screen incident surface 5 in an area where the image light near the focal point of the lens provided on the screen surface on the image source side does not pass through, having a lens shape; A transmissive screen characterized by a Fresnel lens provided on the viewing surface.

5. In a transmission screen that transmits the image light incident from the image source and exits to the image viewing side,

At least one screen of the screen sheet forming the screen has a screen surface on the image source side which is formed by continuously arranging a plurality of lenses for condensing image light. Has a configuration in which a plurality of base materials are joined, and the refractive index of the base material located on the image generation source side is n and the refractive index of the base material located on the image viewing side is η. In case

n <n.

The focal point of each lens provided on the screen surface on the image source side is located closer to the image viewing side than the bonding surface of the base material, and the bonding surface is concave toward the image viewing side. A light absorbing layer substantially parallel to the screen incident surface in a region where the image light does not pass near the focal point of a lens provided on the screen surface on the image generating source side and which has a lens shape, and A transmission screen characterized by a Fresnel lens provided on the screen surface on the image viewing side.

6. The transmission screen according to claim 1, wherein the screen sheet is composed of two types of base materials having different refractive indexes, and a screen surface on the image source side is perpendicular to the screen screen. The lens has a shape in which a plurality of lenticular lenses having a longitudinal direction are arranged continuously in the horizontal direction of the screen screen, and the focal point of each lens is located near the joint surface of the two types of base materials. The surface has a lens shape for converting the condensed image light into substantially parallel light, and a light absorbing layer is provided in a region where the image light near the focal point of the lens provided on the screen surface on the image source side does not pass through. A transmission screen characterized in that a Fresnel lens is provided on the screen surface on the image viewing side.

7. In a transmission screen that transmits image light incident from the image source side and emits it to the image viewing side,

At least one of the screen sheets forming the screen has a configuration in which base materials having different refractive indices are joined, and the screen surface on the image source side condenses the image light. The focal point of each lens is located near the bonding surface of the substrate, and the bonding surface has a lens shape that converts the focused image light into substantially parallel light. A light absorbing layer is provided in an area where the image light near the focal point of the lens provided on the screen surface on the image generation source side does not pass through, and the image viewing side screen surface is flat. Transmission screen.

8. In a transmissive screen that transmits image light incident from the image source side and emits it to the image viewing side,

At least one of the screen sheets forming the screen is bent. It has a structure in which substrates with different bending ratios are bonded, and the screen surface on the image source side is made up of a plurality of lenses that condense image light continuously arranged, and the focal point of each lens Is located near the bonding surface of the base material, the bonding surface having a lens shape for converting the focused image light into substantially parallel light, and a lens provided on the screen surface on the image generation source side. A transmission screen characterized in that a light absorbing layer is provided in a region near the focal point where video light does not pass, and the screen surface on the image viewing side is a light diffusing surface.

9. In a transmission screen that transmits image light incident from the image source side and emits it to the image viewing side,

At least one of the screen sheets forming the screen has a configuration in which substrates having different refractive indices are joined, and the screen surface on the image source side has a plurality of screens for condensing image light. The focal point of each lens is located near the bonding surface of the base material, and the optical axis of the lens and the image light provided on the bonding surface are converted into substantially parallel light. The optical axis of the lens to be adjusted substantially coincides with the center of the outer shape of the screen sheet, and the shift amount of the optical axis increases toward the upper and lower ends. A transmissive screen characterized by having a light absorbing layer in a region near the focal point of the provided lens through which image light does not pass and a Fresnel lens provided on a screen surface on the image viewing side.

10. In a transmission screen that transmits image light incident from the image source side and emits it to the image viewing side,

The screen is composed of a plurality of screen sheets, and the first screen sheet closest to the image generation source side of the screen sheets is formed by bonding substrates having different refractive indices. The screen surface on the image source side has a shape in which a plurality of first lenticular lenses having the longitudinal direction in the horizontal direction of the screen are continuously arranged in the vertical direction of the screen. Wherein the focal point of each lens is located near the bonding surface of the base material, and the bonding surface has a lens shape for converting the focused image light into substantially parallel light, and the image light near the focus A light-absorbing layer in an area through which no light passes, and a Fresnel lens on the image viewing-side screen surface, and a second screen sheet positioned on the image viewing side of the first screen sheet. The screen shape on the image source side has a shape in which a plurality of second lenticular lenses having a longitudinal direction perpendicular to the screen screen are arranged continuously in the horizontal direction of the screen screen. The screen surface on the viewing side has a shape in which a plurality of third lenticular lenses whose longitudinal direction is the screen screen vertical direction are substantially opposed to the second lenticular lens and are continuously arranged in the horizontal direction of the screen screen. Has Jo, the second is screen screen horizontal direction of the cross-sectional shape of the Renchikiyura first lens, the transmission type disk re Ichin a configuration in which the shape is convex to the image generation source side and feature.

1 1. In a transmission screen that transmits image light incident from the image source side and emits it to the image viewing side,

The screen is composed of a plurality of screen sheets, and among the screen sheets, a first screen sheet closest to the video source side has a screen surface on the video source side. A second screen sheet that is flat and has a Fresnel lens on the image viewing side screen surface, and a second screen sheet positioned on the image viewing side with respect to the first screen sheet has a different refractive index. The shape of the screen surface on the image source side is a shape in which a plurality of first lenticular lenses whose longitudinal direction is the horizontal direction of the screen screen are arranged continuously in the vertical direction of the screen screen. Wherein the focal point of each lens is located near the joint surface of the substrate, and the joint surface has a lens shape for converting the collected image light into substantially parallel light, and the image light near the focal point Light absorption layer in the area where does not pass Provided, and a plane or a light diffusing surface disk Li one down surface of the image viewing side The screen shape on the image source side of the third screen sheet located on the image viewing side of the second screen sheet has a plurality of screens whose longitudinal direction is the vertical direction of the screen screen. The second lenticular lens has a shape in which two second lenticular lenses are continuously arranged in the horizontal direction of the screen screen, and the shape of the screen surface on the image viewing side is a plurality of second lenticular lenses whose longitudinal direction is in the vertical direction of the screen screen. The third lenticular lens is arranged so as to be substantially continuously opposed to the second lenticular lens in the horizontal direction of the screen screen, and the cross-sectional shape of the second lenticular lens in the horizontal direction of the screen surface is projected. A transmissive screen characterized by a configuration that is convex toward the image source side.

1 2. A projection lens is arranged in front of the image source, and the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, and tenth of the claims are arranged on an image plane in front of the projection lens. Or a rear projection type image display device in which the transmission type screen according to item 11 is arranged.

13. A method of manufacturing a transmission screen using a screen sheet comprising first and second base materials having different refractive indices,

The first base material of the screen sheet is attached to a first die roll having a matrix having a shape of a light incident surface of the screen sheet and a bonding surface of the second base material of the screen sheet. A thermoplastic resin sheet is passed between a second mold roll having a matrix to be provided, and the shape of the incident surface and the shape of the joining surface are formed on the thermoplastic resin sheet. A light absorber is printed on the flat portion formed on the surface, and then the screen sheet is cut and manufactured. Further, a stamper having a matrix of the shape of the light emitting surface of the screen sheet is formed on the stamper. Filling the substrate 2 with an ultraviolet curable resin or an electron beam curable resin, bringing the substrate into contact with the contact surface of the screen sheet, and irradiating ultraviolet light or an electron beam to obtain the shape of the light emitting surface. A method for manufacturing a transmission screen characterized by the following.

1 4. A rear projection type image display device using a transmission screen manufactured by the method according to claim 13.