JP4196483B2 - Projection screen and projection-type image display device using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides a projection screen having directivity in light scattering characteristics and different scattering properties according to the incident angle of light (or having incident angle selectivity), and visibility of a display image using the projection screen ( The present invention relates to a projection type image display apparatus with improved brightness and contrast.
[0002]
As the above-mentioned projection type image display device, a projection image from a projection device (projector) is scattered and transmitted by a transmission type screen to be observed by an observer, or is reflected and reflected by a reflection type screen. And a reflective display device of the type that the viewer can see.
[0003]
[Prior art]
The projection type image display device includes a transmissive or reflective screen for enlarging and projecting a display image to be projected.
As a conventional transmission type screen, a light scattering sheet in which a resin sheet whose surface is processed into a mat shape, a resin sheet containing a diffusing material inside, or a lens sheet is used.
As the reflection type screen, a light scattering reflection sheet having a structure in which a light reflection layer is provided on the front surface (or back surface) of the light scattering sheet is used.
[0004]
In the case of a screen using a resin sheet whose surface is processed into a mat or a light scattering sheet containing a diffusing material inside, the directivity of light scattering (characteristics related to the range / direction of scattered outgoing light. It is difficult in principle to provide a function for controlling the control (referred to as “sex”), and such a function is not actually provided.
For this reason, there is a problem that scattered light of the display image is generated in an unnecessary direction, and as a result, the display luminance is lowered.
[0005]
In the screen combined with the lens sheet, the scattering directivity can be controlled by optimizing the refractive index of the sheet material and the lens shape, and the display brightness can be improved. There is a problem that the contrast of the display image is lowered due to scattering and reflection of unnecessary light and ambient light.
[0006]
[Problems to be solved by the invention]
The present invention provides a projection screen (and a projection-type image display device using the same) that controls the scattering directivity and eliminates the decrease in display brightness and contrast due to unnecessary scattering transmission (or scattering reflection). The purpose is to do.
[0007]
[Means for Solving the Problems]
The projection screen according to claim 1,
A light scattering layer made of a transparent resin layer is formed on one side of the transparent support substrate, and the transparent support substrate on the side where the light scattering layer is not formed, or between the transparent support substrate and the light scattering layer. A projection screen on which a light reflecting layer is formed,
Inside the resin layer, parts with different refractive indexes are randomly distributed in shape and size,
The structure is a light and shade pattern consisting of high and low refractive index,
The screen surface is exposed in a vertically or horizontally long shape,
The screen cross-section is distributed at a specific angle,
For light incident at an angle of a specific range, the range / direction is controlled to be scattered and reflected, and light incident at other angles is reflected without being scattered, and functions as a reflection type. .
[0009]
<Action>
The projection screen of the present invention can easily control the scattering directivity, can appropriately set the observation range (viewing zone) of the display image, and can improve the display luminance in the setting range. .
In addition, because it has incident angle selectivity, image light projected from the projector is scattered within an appropriate range, but light incident from other directions (eg, ambient light) is directly transmitted without being scattered. Contrast reduction due to light other than image light is not caused.
These are common regardless of the screen type (transmission type / reflection type).
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the drawings.
<Embodiment 1>
FIG. 1 is an explanatory view of a transmission screen according to claim 1, wherein the left side is a plan view and the right side is a cross-sectional view.
[0011]
The screen 1 is composed of a transparent support substrate 3 and a light scattering layer 2 formed thereon. Inside the light scattering layer 2, the shape and size are irregular parts with different refractive indexes (in the same figure). The portion shown in black is exposed in a horizontally long shape on the surface, and in the depth (thickness) direction, it is distributed at a specific angle so that a light and shade pattern consisting of a high and low refractive index is formed. It has a formed structure.
In the cross-sectional view of FIG. 1, the refractive index is uniform (the color does not change in the inclined direction) in the direction in which the portions having different refractive indexes are distributed.
[0012]
FIG. 2 is an explanatory view according to another embodiment of the transmissive screen according to claim 1, wherein the left side is a plan view and the right side is a cross-sectional view.
In the plan view of FIG. 2, on the surface of the screen, the portions having different refractive indexes are exposed in a vertically long shape. According to the cross-sectional view, the distribution direction of the portions having different refractive indexes is constant. The refractive index is irregularly distributed.
[0013]
The optical characteristics of the screens of FIGS. 1 and 2 are first considered in plan views.
When the shape of the part with different refractive index is vertically long (or horizontally long), when light incident on that part is scattered and emitted, the light scattering characteristics of the light emitted from each part are horizontally long (or vertically long). Anisotropy (scattering directivity).
[0014]
In FIG. 1, since the shape is horizontally long, the emitted light is scattered vertically. In FIG. 2, since the shape is vertically long, the emitted light is scattered horizontally.
This will be described later in the screen manufacturing process.
[0015]
Next, considering the cross-sectional view,
Light scattering occurs for light incident at an angle close to an angle along the direction in which the portions having different refractive indexes are directed (the direction of the arrow 4 in the figure, which forms an angle θ from the normal of the film). Become.
For light incident at an angle perpendicular to the above direction (the direction of arrow 5 in the figure), it functions as a simple transparent sheet, and the incident light is emitted without being scattered.
[0016]
FIG. 3 is an example of a graph showing the incident angle selectivity of the screen.
As indicated by the solid line 6 in the figure, the haze value is 80% or more for light in a specific incident angle range (0 to 60 degrees in the figure), and conversely, the incident angle (-60 in the figure is symmetrical). The haze value with respect to light of from 0 degree to 0 degree is 20% or less, which indicates the incident angle selectivity of the light scattering characteristic.
[0017]
As shown in the figure, the incident angle selectivity has a certain angle width, and as described above, the incident light is scattered in the range of 0 degree to 60 degrees, and the light from -60 degrees to 0 degree is scattered. Can be transmitted directly.
This angular width of 60 degrees is merely an example, and this angular width can be controlled by a manufacturing method and a manufacturing medium.
[0018]
In addition, as described above, when the shape of the portion having different refractive index is vertically long (or horizontally long), when the light incident on the portion is scattered and emitted, the light scattering characteristics of the emitted light from each portion However, it has anisotropy (scattering directivity) which becomes horizontally long (or vertically long).
For example, when the shape is horizontally long as shown in FIG. 1, the scattered emitted light from the screen has a distribution that becomes a vertically long ellipse as shown in FIG.
[0019]
Next, the structure of the screen 1 of the present invention will be described in detail.
The screen 1 of the present invention has a two-layer structure of a transparent support substrate 3 and a light scattering layer (resin layer) 2. The light scattering layer 2 is a light scattering layer made of a resin film, such as a transparent adhesive material (not shown). Laminated by. Or if it can provide the light-scattering layer 2 which has the effect of this invention on the transparent support substrate 3 not only by a lamination but by a coating | coating other system, there will be no limitation in the system in particular.
[0020]
Inside the resin layer 2, portions having different refractive indexes are irregularly shaped and sized, exposed on the surface in a vertically or horizontally elongated shape, and inclined at a specific angle in the depth (thickness) direction. As a result, a shading pattern having a high and low refractive index is formed.
[0021]
If the difference in refractive index is too small, the scattering property is deteriorated. On the other hand, if the difference is too large, light scattering occurs regardless of the angle at which light is incident. It becomes difficult.
[0022]
For this reason, light scattering does not occur only by the difference in refractive index on the surface, and it is necessary that the difference in refractive index be such that the light scattering layer 2 has sufficient scattering properties due to its thickness.
In the present invention, the refractive index difference is appropriately selected in the range of 0.001 to 0.2 so as to satisfy the above conditions, and the thickness of the light scattering layer 2 is similarly in the range of 1000 μm to 1 μm depending on the refractive index difference. Is selected as appropriate.
[0023]
As an example, a light and shade pattern is formed by distributing a portion having a refractive index of 1.56 (refractive index difference of 0.04) in the light scattering layer 2 having an average refractive index of 1.52 and a thickness of 20 μm. Thus, a screen 1 having sufficient scattering property and incident angle selectivity could be obtained.
[0024]
Since the refractive index difference that can be recorded is limited by the manufacturing method and the recording material, the light scattering layer 2 is made thin if it has a large refractive index difference, and the light scattering layer 2 is made thick if it has a small refractive index difference. Thus, the screen of the present invention can be realized.
[0025]
The sizes of the portions having different refractive indexes are random and non-regular in order to cause light scattering, but the average size is in the range of 0.1 μm to 300 μm in diameter in order to have the necessary scattering properties. Of these, it is appropriately selected according to the required light scattering characteristics for each application of the screen.
[0026]
As an example, a light-scattering characteristic having a scattering spread of about ± 40 degrees was realized by using a light and shade pattern consisting of high and low refractive indexes having an average size of 12 μm.
[0027]
<Embodiment 2>
FIG. 5 is an explanatory view (cross-sectional view) relating to a reflective screen according to claim 2.
The reflection type screen 7 is configured by providing a light reflection layer 8 on the transmission type screen 1 shown in FIGS. As shown in FIG. 5, the light reflection layer 8 may be formed between the light scattering layer 2 and the transparent support substrate 3, or the surface of the transparent support substrate 3 opposite to the light scattering layer 2 (not shown). But it ’s okay.
[0028]
The light reflecting layer 8 is formed, for example, by vapor-depositing a light reflecting metal on the back surface of the resin layer. In addition, the reflective screen 7 of the present invention can be obtained as long as a light reflective material can be applied to the back surface of the resin layer 2 by a technique such as lamination, coating, or sputtering.
[0029]
In FIG. 5, light scattering is applied to incident light at an angle close to an angle along the direction in which the portions having different refractive indices are directed (the direction of the arrow 4 in the figure, which forms an angle θ from the normal of the film). Will occur.
[0030]
For this reason, as shown in the figure, when incident light is incident from the direction of the arrow 5 in the figure, no light scattering occurs and the light passes through the resin layer 2, but after being reflected by the back reflection layer 8, the resin layer 2 again. Is incident from the direction of the arrow 4 in the figure, light scattering occurs.
However, the range in which the scattered light spreads depends on the shape of the shade pattern exposed on the screen surface, as in the case of the transmission screen.
[0031]
Alternatively, even if light is scattered at the time of incidence rather than at the time of light emission by changing the inclination angle of the portion having a different refractive index in the light scattering layer (the case where the incident light enters from the direction of the arrow 4) And the like, and light scattering may occur both at the time of incidence and at the time of emission.
[0032]
<Embodiment 3>
FIG. 6 is an explanatory diagram showing an outline of an example of a projection-type image display device.
The projection type image display device (transmission type) includes a light source 9, an image display unit 10, a projection lens system 11, and a projection screen 1 as shown in the figure.
[0033]
In the projection type image display apparatus of the present invention, the screen 1 is characterized as described above, and the light source 9, the image display unit 10, and the projection lens system 11 are not particularly limited, and the image display unit 10 and the light source 9 are illustrated. In addition, a so-called “liquid crystal projector” or “slide projector” which is a separate body, or a “CRT type projector” where they are the same body may be used.
[0034]
A small size image displayed on the image display unit 10 using the light of the light source 9 is enlarged and projected by the projection lens system 11 to form a large size image on the screen 1. The image light 13 scattered on the screen 1 reaches the eyes of the observer and the image is recognized. At this time, the range of the image light 13 scattered from the screen 1 is specified by the scattering directivity of the screen 1. The light is emitted in a limited range.
Therefore, if the light intensity of the image light 14 is the same, the amount of light incident on the observer's eyes is increased compared to a conventional screen in which the scattering range cannot be specified, thereby improving the display brightness.
[0035]
Although the display brightness is improved in the same manner as a screen using a lens sheet, the phenomenon of a decrease in display contrast due to unnecessary scattered light emitted from a lens end face or the like seen when using a lens sheet is the screen of the present invention. Then it does not happen.
[0036]
On the other hand, when ambient light 15 typified by room illumination light or the like is incident on the screen 1, even when a lens sheet is used in a conventional screen, scattering reflection occurs on the surface, leading to a decrease in display contrast. In the invention, the image display light 14 and the ambient light 15 have different incident angles with respect to the screen 1, so that the image 1 is directly transmitted without being scattered due to the incident angle selectivity of the screen 1.
For this reason, the display contrast is not lowered by the ambient light 15, and high-contrast image display is possible.
[0037]
<Embodiment 4>
FIG. 7 is an explanatory diagram showing an outline of another example (reflection type) of the projection type image display apparatus.
In the present embodiment, the screen 7 is a reflection type, and the image display unit 10 and the projection lens system 11 are on the observer side.
[0038]
The small size image displayed on the image display unit 10 using the light of the light source 9 is enlarged and projected by the projection lens system 11 to form a large size image on the screen 7. The image light 13 scattered and reflected by the screen 7 reaches the observer's eyes and the image is recognized. At this time, the range of the image light 13 that is scattered and reflected from the screen 7 depends on the scattering directivity of the screen 7. The light is emitted limited to a specific range.
Therefore, if the light intensity of the image light 14 is the same, the amount of light incident on the observer's eyes is increased compared to a conventional screen in which the scattering range cannot be specified, thereby improving the display brightness.
[0039]
Although the display brightness is improved in the same manner as a screen using a lens sheet, the phenomenon of a decrease in display contrast due to unnecessary scattered light emitted from a lens end face or the like seen when using a lens sheet is the screen of the present invention. Then it does not happen.
[0040]
On the other hand, when ambient light typified by room illumination light or the like is incident on the screen 7, even if a conventional screen uses a lens sheet, scattering reflection occurs and the display contrast is lowered. Since the incident angle to the screen 7 is different between the display light and the ambient light, it is directly reflected without being scattered due to the incident angle selectivity of the screen 7.
Since the direction of the reflected light 16 is emitted in the same direction as the reflection of the ambient illumination light source (such as a room lamp) on the outermost surface of the screen 7 (such as the protective layer), it is naturally different from the direction of the observer. It has no effect on display image observation. For this reason, the display contrast is not reduced by the ambient light 14, and high-contrast image display is possible.
[0041]
The means for producing the screen of the present invention will be described below.
The screen 1 (transmission type) of the present invention is produced by forming a light scattering layer (resin layer) 2 on a transparent support substrate 3.
The light scattering layer 2 can be obtained by imparting desired light scattering characteristics to the photosensitive resin film by optical exposure means.
[0042]
Adhesion between the light scattering layer 2 and the transparent support substrate 3 uses a transparent adhesive material.
In the case of the reflective screen 7, after the aluminum metal is vapor-deposited on the back surface (opposite to the observer) of the photosensitive resin film imparted with the desired light scattering characteristics by the optical exposure means, the transparent support substrate 3 is used. It is affixed using an adhesive material.
[0043]
Hereinafter, an example of a method for producing the light scattering layer (resin layer) 2 will be described.
FIG. 8 is an explanatory diagram showing an example of an optical system manufactured using a speckle pattern, which is a complicated interference pattern caused by scattered laser light.
[0044]
The ground glass 18 is irradiated with laser light emitted from the laser light source 17.
A photosensitive material 19 is arranged at a predetermined distance F on the surface opposite to the laser irradiation side of the frosted glass 18, and a speckle pattern which is a complicated interference pattern generated by laser light transmitted and scattered by the frosted glass 18 is a photosensitive material 19. Is exposed to light.
[0045]
At this time, as shown in the figure, the ground glass 18 and the photosensitive material 19 are arranged to be inclined at a predetermined angle α, so that the speckle pattern is exposed in the photosensitive material 19 at a predetermined angle.
[0046]
Since this angle corresponds to the inclination of the portion having a different refractive index in the light scattering layer 2 in the screen 1 (7) of the present invention (that is, the scattering peak angle θ of the incident angle selectivity), the angle is Depending on the incident angle of the display image light to the screen 1 (7), it is appropriately selected within the range of about 0 to 60 degrees.
[0047]
At this time, θ = 0 degrees means that the portions having different refractive indexes in the light scattering layer 2 are perpendicular to the front and back surfaces of the screen 1 (7). Alternatively, image light 14 coming from the front (in the case of a reflective screen) can be scattered and observed, and ambient light 15 coming from above the screen (such as the ceiling in the room) or below (floor) is directly transmitted (reflected). It has a function.
[0048]
The laser light source 17 used for recording can be used by appropriately selecting the wavelength of 514.5 nm, 488 nm or 457.9 nm of an argon ion laser according to the sensitivity of the photosensitive material 19.
Other than argon ion lasers, any laser light source with good coherency can be used. For example, a helium neon laser or a krypton ion laser can be used.
[0049]
The speckle pattern is a bright and dark speckle pattern that occurs when light with good coherence is scattered or reflected or transmitted by a rough surface, and occurs because light scattered by minute irregularities on the rough surface interferes with an irregular phase relationship. Is.
[0050]
According to the description (p.266-p.268) of “Optical Measurement Handbook Asakura Shoten, Toshiharu Tadashi et al., Published November 25, 1994”, speckle patterns with random values of concentration and phase depending on position ,
The average size of the pattern is determined in inverse proportion to the angle at which the ground glass 18 is viewed from the photosensitive material 19.
[0051]
Therefore, when the size of the ground glass 18 is increased in the vertical direction than in the horizontal direction, the pattern recorded on the photosensitive material 19 is finer in the vertical direction than in the horizontal direction.
In the speckle pattern by the manufacturing method in the optical system of FIG. 8, the wavelength λ of the laser light to be used, the size D of the ground glass 18 and the distance F between the ground glass 18 and the photosensitive material 19 are the average of the recorded speckle pattern. The size d is determined. Generally, d is expressed by the following equation.
d = 1.2λF / D
The average length t in the depth direction of the speckle pattern is t = 4.0λ (F / D) 2.
It is represented by
[0052]
As described above, by optimizing the values of λ and F / D, the light scattering layer 2 having a desired three-dimensional refractive index distribution so as to have a desired scattering property can be obtained.
As an example, when λ = 0.5 μm and F / D = 2, d = 1.2 μm, t = 8 μm, and the shading pattern on the surface of the light scattering layer 2 is distributed with an average of 1.2 μm. In the thickness direction of 2, the average size of 8 μm is distributed in the direction according to the inclination angle.
[0053]
However, these sizes are only average sizes. Actually, these sizes are centered on these sizes, and the portions with different refractive indexes are distributed on the surface and inclined in the depth direction. Thus, the light scattering layer 2 constituting the screen 1 (7) of the present invention as shown in FIGS. 1 and 2 is obtained.
[0054]
In order to give light scattering a scattering directivity, the size of the ground glass 18 can be made different vertically and horizontally so as to be rectangular or elliptical, so that the optical system shown in FIG. 8 can be used.
For example, the size D of the ground glass 18 is different in the vertical (y) direction and the horizontal (x) direction, and the above (F / Dx) = 2, (F / Dy) = 20, and other conditions are as described above. If it is the same, the average size dx = 1.2 μm in the horizontal direction of the speckle pattern and the average size dy = 12 μm in the vertical direction, and an average size speckle pattern with an aspect ratio of 1:10 is obtained.
[0055]
By exposing this, a light scattering layer 2 having scattering directivities with different vertical and horizontal scattering properties can be obtained, and by laminating on the transparent support substrate 3, the screen 1 (7) of the present invention can be obtained. .
[0056]
The above-described manufacturing means is merely an example, and the present invention is not limited to this. The screen of the present invention may be realized even in a manufacturing method that is not an optical exposure means. For example, there is a possibility that a transparent diffuser having a random rugby ball shape in a transparent resin may be produced by irregularly embedding a large number of transparent diffusers at a predetermined angle.
[0057]
【The invention's effect】
When the display image light is incident on the screen, the spread of the display scattered light has different scattering directivity, so that the display image light can be emitted only in the necessary direction. There is an effect of improving display brightness without causing necessary scattering.
In addition, the display image light incident on the screen expands the image observation viewing area by causing light scattering, and ambient light incident at a different angle from the display image light is directly transmitted or transmitted without causing light scattering. Since the reflected light scattering property has an incident angle selectivity, the display contrast is improved.
[0058]
[Brief description of the drawings]
FIG. 1 is an explanatory view showing an example of a transmission screen according to the present invention, a left side is a plan view and a right side is a cross-sectional view.
FIG. 2 is an explanatory diagram showing another example of the transmission screen according to the present invention, in which the left side is a plan view and the right side is a cross-sectional view.
FIG. 3 is a graph showing an example of incident angle selectivity of the screen of the present invention.
FIG. 4 is an explanatory diagram of light scattering directivity of the screen of the present invention.
FIG. 5 is a schematic cross-sectional view showing a reflective screen of the present invention.
FIG. 6 is an explanatory diagram conceptually showing a main part of a projection type image display apparatus (transmission type) according to the present invention.
FIG. 7 is an explanatory diagram conceptually showing the main part of another projection type image display apparatus (reflection type) according to the present invention.
FIG. 8 is an explanatory view showing an example of an optical system for producing a light scattering film having the structure shown in FIG. 2 using a speckle pattern.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Light-scattering film 2 ... Light-scattering layer 3 ... Transmission support substrate 4 ... Light incident from a scattering direction 5 ... Light incident from a transmission direction 6 ... Plot 7 of measured haze value ... Reflection screen 8 ... Reflection layer 9 ... Light source DESCRIPTION OF SYMBOLS 10 ... Image display part 11 ... Projection lens system 12 ... Collimator lens 13 ... Scattering display image light 14 ... Display image light 15 ... Ambient light 16 ... Direct reflection light 17 ... Laser light source 18 ... Ground glass 19 ... Photosensitive material 20 ... Laser light 21 ... Beam expander 22 ... Collimator lens

Claims (1)

A light scattering layer made of a transparent resin layer is formed on one side of the transparent support substrate, and the transparent support substrate on the side where the light scattering layer is not formed, or between the transparent support substrate and the light scattering layer. A projection screen on which a light reflecting layer is formed ,
Inside the resin layer, parts with different refractive indexes are randomly distributed in shape and size,
The structure is a light and shade pattern consisting of high and low refractive index,
The screen surface is exposed in a vertically or horizontally long shape,
The screen cross-section is distributed at a specific angle,
For light incident at an angle of a specific range, the range / direction is controlled to be scattered and reflected, and light incident at other angles is reflected without being scattered, and functions as a reflection type. Projection screen.

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