JP2003167109A - Light diffusing body and display using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light diffusing body in which the emission range (visual range) of light is arbitrarily set, a display having a very high luminance is given by enhancing the utility efficiency of light, which has also a compact structure, and which is inexpensive, and further, is thin and light. <P>SOLUTION: The light diffusing body is composed of a plurality of square cells 4 composed of kinoform 3, which have a function with which diffracted light having a preliminarily defined special extension with respect to incident light which has a preliminarily defined incident angle and a specific wavelength is emitted, are disposed in a form of orthogonal matrix on a flat substrate 2, and the surface of each of the cells 4 is composed of a material having light reflectivity or each of the cells 4 is composed of a material having light transmissivity. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light diffuser for diffusing light and a display device using the light diffuser, and in particular, the emission range of light, that is, the visual range can be set by a diffractive optical action. The present invention relates to a light diffuser that enhances light utilization efficiency and enables display with extremely high brightness, and a display device using the light diffuser.

[0002]

2. Description of the Related Art Conventionally, as one of reflection type display devices, for example, external light such as natural light or room light incident from the front of a transmission type display body such as a liquid crystal display element for controlling transmission of light for display. Is reflected by a scattering reflection plate, and the transmissive display is illuminated by the reflected light from the back surface for display.

However, in the reflection type display device of this type, the light reflected by the scattering reflection plate is widely diffused to the direction in which it does not enter the transmission type display body, so that the reflection light which can be used as illumination light is a transmission type display. Only the light in the diffusion range that is incident on the body, the spread angle of the light that passes through the transmissive display and is emitted in front of it is large, and the intensity of the light that is emitted in the display viewing direction is low. Therefore, there is a problem that the display is dark.

Therefore, recently, as a means for solving such a problem, for example, "Japanese Patent Laid-Open No. 11-287991" has been proposed.
As shown in Japanese Patent Laid-Open Publication No. ", a reflection type display device using a diffusing means having a geometrical optical effect has been proposed.

That is, this reflection type display device is arranged so as to face the rear surface of the transmission type display body and reflect the incident light from the front of the transmission type display body in a predetermined direction with a spread angle smaller than the incident angle range. Diffuser having a geometrical optical effect on at least one of the front surface of the transmissive display body and the back surface of the transmissive display body and the front surface of the directional reflective plate while the reflective reflector is arranged. By providing the display, the display observed from a predetermined direction can be made sufficiently bright and the viewing angle can be widened.

[0006]

By the way, in the reflection type display device using the conventional diffusing means of this kind, the light is controlled by the diffusing means having a geometrical optical function. The diffusion means that has the
There are problems to be solved, such as the structure being relatively large and expensive, the thickness being thick, and the weight being heavy.

On the other hand, among the diffusing means having a geometrical optical effect, the scattering plate (diffusing plate) can be formed with a relatively simple structure, but it is difficult to control the light emission range. Is.

The object of the present invention is to allow the emission range (viewing area) of light to be arbitrarily set by the action of diffractive optics, and further to improve the utilization efficiency of light to display with extremely high brightness. An object of the present invention is to provide a light diffuser having a possible configuration that is small, inexpensive, and thin and lightweight, and a display device using the same.

[0009]

In order to achieve the above object, in the invention corresponding to claim 1, a reflection type light diffuser for diffusing light is predetermined on a flat substrate. The surface of each cell is formed by arranging a plurality of cells made of kinoform having a function of emitting diffracted light having a predefined spatial spread with respect to incident light of a specific wavelength at an incident angle. However, it is made of a material having light reflectivity.

Therefore, in the light diffuser of the invention according to claim 1, the light diffuser has a predetermined spatial spread on the plane substrate for the incident light of the specific wavelength of the predetermined incident angle. When a plurality of cells made of kinoform having a function of emitting diffracted light are arranged, and the surface of each cell is made of a material having light reflectivity, kinoform is formed when light enters. Due to the diffractive optical action of the foam, light can be emitted to a preset spatial region, so that the preset light diffusivity can be realized as the entire light scatterer. That is, by disposing a kinoform that has the function of emitting light in a spatial region (corresponding to the viewing region when observed) for each individual use, the light diffusion suitable for each is achieved. It is possible to obtain a light diffuser having properties. Here, as compared with the conventional non-directional diffusion (scattering), the light diffuser of the present invention eliminates the distribution of light to unnecessary spatial regions and emits light only to necessary spatial regions. Therefore, the light utilization efficiency can be improved (compared to the case where the function of diffusing light is realized by arranging cells composed of diffraction gratings in the related art, in the kinoform, 1
Generation of diffracted light other than the secondary diffracted light and the effect of diffraction due to the size and shape of the cell can be minimized, so that the light utilization efficiency can be increased. Furthermore, since the diffraction efficiency of each kinoform can be set to almost 100%, a light diffuser having extremely high light utilization efficiency can be obtained. Further, by using kinoform as a constituent element of the light diffuser, it is possible to make the light intensity distribution uniform in the spatial region where the emitted light is distributed, or to locally increase or decrease the intensity. That is, when the light intensity distribution is uniform, when observing from within the corresponding spatial region,
It looks stable and shines with the same brightness. On the other hand, when the intensity is locally increased, it is possible to easily realize a light diffuser that has the maximum brightness mainly from the viewpoint to be observed and gradually becomes darker as the position of the viewpoint shifts. .

Further, in the invention according to claim 2, in the transmission type light diffuser for diffusing light, the incident light of a specific wavelength having a predetermined incident angle is previously defined on a planar substrate. A plurality of cells made of kinoform having a function of emitting diffracted light having the above-described spatial spread are arranged, and each cell is made of a light-transmitting material.

Therefore, in the light diffuser of the invention according to claim 2, the light diffuser has a predetermined spatial spread on the plane substrate with respect to the incident light of the specific wavelength having the predetermined incident angle. A plurality of cells made of kinoform having a function of emitting diffracted light are arranged, and each cell is made of a light-transmitting material, so that the kinoform of Since light can be emitted to a preset spatial region by the diffractive optical effect, preset light diffusivity can be realized as the entire light scatterer. That is, by disposing a kinoform that has the function of emitting light in a spatial region (corresponding to the viewing region when observed) for each individual use, the light diffusion suitable for each is achieved. It is possible to obtain a light diffuser having properties. Here, compared to conventional omnidirectional diffusion (scattering),
In the light diffuser of the present invention, it is possible to eliminate the distribution of light to an unnecessary spatial area and to emit the light only to the necessary spatial area, so that it is possible to improve the light utilization efficiency (conventional). Compared to the case where cells with different diffraction gratings are arranged and the function of diffusing light is realized, kinoform minimizes the generation of diffracted light other than the first-order diffracted light and the effect of diffraction due to the size and shape of the cell. Therefore, the efficiency of light utilization can be increased). Furthermore, since the diffraction efficiency of each kinoform can be set to almost 100%, a light diffuser having extremely high light utilization efficiency can be obtained. Further, by using kinoform as a constituent element of the light diffuser, it is possible to make the light intensity distribution uniform in the spatial region where the emitted light is distributed, or to locally increase or decrease the intensity. That is, when the light intensity distribution is uniform, when observing from within the corresponding spatial region,
It looks stable and shines with the same brightness. On the other hand, when the intensity is locally increased, it is possible to easily realize a light diffuser that has the maximum brightness mainly from the viewpoint to be observed and gradually becomes darker as the position of the viewpoint shifts. .

On the other hand, in the invention according to claim 3, in the light diffuser of the invention according to claim 1 or 2, all the cells arranged on the planar substrate are the same as each other. It consists of a kinoform with a phase modulation pattern.

Therefore, in the light diffuser of the invention according to claim 3, all the cells arranged on the planar substrate are made of kinoforms having the same phase modulation pattern. The foam phase distribution may be designed in one kind and can be easily produced. Furthermore, if the observation distance is larger than a certain degree (for example, several times larger than the size of the light diffuser), it is possible to obtain high light utilization efficiency in the angular range corresponding to the set spatial region without depending on the observation distance. .

Further, in the invention according to claim 4, in the light diffuser of the invention according to claim 1 or claim 2, as a kinoform, for incident light of a specific wavelength of a predetermined incident angle, Therefore, the kinoform is used so that the diffracted light emitted from all the cells coincides with each other in a predefined spatial region.

Therefore, in the light diffuser of the invention according to claim 4, as the kinoform, the diffracted light emitted from all the cells is defined in advance with respect to the incident light of a specific wavelength having a predetermined incident angle. By using a kinoform that matches in a defined spatial area, the light distributed outside the spatial area can be minimized, and the desired light intensity distribution can be obtained in the predefined spatial area. Since the light can be formed under the condition that the light utilization efficiency is the highest, it is possible to make the entire light diffuser appear to shine evenly when viewed from a predefined spatial region.

Further, in the invention according to claim 5, in the light diffuser of the invention according to any one of claims 1 to 4, the angular range of the light emitted from each cell is horizontal. It has a spread of 12 ° or more in the direction.

Therefore, in the light diffuser of the invention according to claim 5, the angular range of the light emitted from each cell is
By having a spread of 12 ° or more in the horizontal direction, a wide viewing area can be secured in the horizontal direction, and in particular, diffracted light is incident on both eyes, so there is a difference in brightness between the eyes and flickering. It is possible to make observations with less discomfort.

On the other hand, in the invention according to claim 6, in the light diffuser of the invention according to any one of claims 1 to 5, the angular range of the light emitted from each cell is 3 It has a spread of more than °.

Therefore, in the light diffuser of the invention according to claim 6, the angular range of the light emitted from each cell is
By having a spread of 3 ° or more, when illuminated with white light, diffracted light of each wavelength in the visible light band spatially overlaps with each other, suppressing a drastic color change due to wavelength dispersion, It is possible to obtain whitish diffused light, and it is possible to prevent the observation color from changing with respect to a slight movement of the viewpoint, which makes it easier to obtain stable observation conditions.

Further, in the invention according to claim 7, in the light diffuser of the invention according to any one of claims 1 to 6, the maximum diffraction efficiency at a specific wavelength in the visible light band is obtained. Therefore, the amount of phase modulation on the kinoform is set.

Therefore, in the light diffuser of the invention according to claim 7, by setting the amount of phase modulation on the kinoform so that the maximum diffraction efficiency is obtained at a specific wavelength in the visible light band, the naked eye can see. It is possible to realize the maximum brightness at the selected wavelength when observing. Here, even when observing a wavelength different from the selected wavelength, a certain degree of high efficiency can be obtained in most of the visible wavelengths, so that a light diffuser that is highly efficient in the entire visible light and is optimal for observation with the naked eye can be easily obtained. Obtainable.

Further, in the invention according to claim 8, in the light diffuser of the invention according to any one of claims 1 to 7, the kinoform is a surface relief type.

Therefore, in the light diffuser of the invention according to claim 8, since the kenoform is of the surface relief type, it is suitable for mass production by the embossing technique, inexpensive mass production is possible, and the structure is inexpensive. In addition, it can be made thin and lightweight.

On the other hand, in the invention according to claim 9, the light diffuser of the invention according to any one of claims 1 and 3 to 8 is displayed by controlling the transmission of light. It is arranged so as to face the rear surface of the transmissive display.

Therefore, in the display device of the invention according to claim 9, the light diffuser of the invention according to any one of claims 1 and 3 to 8 is used to control the transmission of light. By arranging so as to face the back surface of the transmissive display body to be displayed, the spatial area of the light emitted by the light diffuser can be set as the viewing area of the display device, and an extremely bright display image can be obtained from within the viewing area. It can be observable. In this case, it is possible to make the observed brightness uniform in the viewing area and to suppress the color change in the viewing area.

Further, in the invention corresponding to claim 10, a transmissive display for displaying the light diffuser of the invention according to any one of claims 2 to 8 by controlling light transmission. It is placed facing the back or front of the.

Therefore, in the display device of the invention according to claim 10, the light diffuser of the invention according to any one of claims 2 to 8 is displayed by controlling the transmission of light. By arranging them so as to face the back or front of the transmissive display, the spatial area of the light emitted by the light diffuser can be used as the viewing area of the display device, and an extremely bright display image can be observed from within the viewing area. Can be In this case, it is possible to make the observed brightness uniform in the viewing area and to suppress the color change in the viewing area.

Further, in the invention corresponding to claim 11,
In the display device of the invention according to claim 9 or 10, when the transmissive display has a pixel structure,
At least one cell on the light diffuser for one pixel
I am trying to support more than one.

Therefore, in the display device of the invention according to claim 11, when the transmissive display has a pixel structure, at least one cell on the light diffuser corresponds to one pixel. By doing so, the display image by the display device can be observed as a high-quality image without flicker.

In the display device of the invention according to any of claims 9 to 11, when the illumination light is incident from the transmissive display side (a reflection type light diffuser is used), the illumination light is diffused. In both cases of incidence from the body side (using a transmissive light diffuser), the kinoform acts on the illumination light only once under the optimum conditions, so that the light utilization efficiency is high, An extremely bright display can be realized. Further, since external illumination light can be used with high efficiency, it is not necessary to incorporate a light source, and the display device can be made even thinner.

From the above, due to the diffractive optical action,
A light diffuser which is small in size, inexpensive, thin, and lightweight, and which has a configuration capable of arbitrarily setting the light emission range (viewing area) and further improving the light utilization efficiency to perform display with extremely high brightness, and the same. It is possible to obtain a display device using.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION First, the concept of the present invention will be described.

The light diffuser for diffusing light of the present invention emits diffracted light having a predetermined spatial spread to incident light of a specific wavelength having a predetermined incident angle on a planar substrate. A plurality of cells composed of functional kinoforms are arranged in an array or a matrix, and the surface of each cell is made of a material having light reflectivity or each cell is light transmissive. An external light source of a condition close to a predetermined incident light condition by being combined with a transmissive display body such as a transmissive liquid crystal display panel that controls and displays light transmission. By irradiating the illumination light from a highly efficient pre-designed spatial area, a display device that can display extremely bright images when viewed from this spatial area is configured. Is the gist that the Noh.

Here, the kinoform is an optical element for performing wavefront reproduction by recording only the phase of the wavefront of the object light (light having required characteristics), and the phase of the object light obtained by calculation. In order to create a reproduction light with a distribution, it is converted to the phase modulation amount that acts on the illumination light and recorded, and the amplitude of the illumination light is not changed during reproduction, so there is no loss due to light absorption and high diffraction efficiency. Can be obtained.

Further, an ideal kinoform does not generate many diffraction orders unlike ordinary holograms and diffraction grating patterns, so that the light utilization efficiency is extremely high.

Furthermore, by using the kinoform, it is possible to control the intensity distribution of the diffracted light in an arbitrary region and the emission direction with high accuracy.

The kinoform is disclosed, for example, in "" Holography ": Junpei Tsujiuchi; published by Sokabo Co., Ltd .: pages 45 to 47".

Hereinafter, embodiments of the present invention based on the above concept will be described in detail with reference to the drawings.

(First Embodiment: Corresponding to Claim 1, Claim 2, and Claim 5 to Claim 8) FIG. 1 is a front view showing a structural example of a light diffuser according to the present embodiment. .

That is, as shown in FIG. 1, the light diffuser 1 according to the present embodiment is preliminarily defined on a planar substrate 2 with respect to incident light of a specific wavelength having a predetermined incident angle. It is formed by arranging a plurality of quadrangular cells 4 formed of a kinoform 3 having a function of emitting a diffracted light having a spatial spread in an orthogonal matrix, and the surface of each cell 4 has light reflectivity. Or each cell 4 is made of a light-transmissive material.

Here, the angular range of the light emitted from each cell 4 has a spread of 12 ° or more in the horizontal direction.

Further, the angular range of the light emitted from each cell 4 has a spread of 3 ° or more.

Further, the amount of phase modulation on the kinoform 3 is set so as to maximize the diffraction efficiency at a specific wavelength in the visible light band.

Furthermore, the kinoform 3 is of a reflective surface relief type.

The enlarged view shown on the right side of FIG. 1 shows a configuration example of one cell 4, and the phase modulation pattern of the kinoform 3 constituting the cell 4 is represented in black and white.

For example, for light of a specific wavelength, black corresponds to the phase modulation amount = π, and white corresponds to the phase modulation amount = 0.

Although FIG. 1 is binarized for the sake of convenience, it is actually desirable that the pattern has a continuous phase modulation amount of 0 to 2π.

In order to realize such phase modulation,
Since it can be realized if the thickness is half the specific wavelength (in the case of a reflection type surface relief structure), an extremely thin light diffuser can be realized.

Next, in the light diffuser 1 according to this embodiment configured as described above, the kinoform 3 forming the cell 4 acts so as to modulate the local phase of the incident light, and An arbitrary diffracted light is emitted with respect to the determined incident light, and the phase modulation can be realized by, for example, a minute surface relief structure.

The kinoform 3 has a phase modulation amount of 0 to 2π with respect to light of a certain specific wavelength, so that the kinoform 3 functions most effectively, and is 100%. It is also possible to obtain the diffraction efficiency of.

Therefore, the light diffuser 1 according to this embodiment using such a kinoform 3 as the cell 4 also has
An extremely high light utilization efficiency can be obtained.

In particular, when used as the light diffuser 1 for display use, by selecting a specific wavelength within the wavelength band of visible light, the maximum brightness is provided at the selected wavelength when observed with the naked eye. be able to.

Even when the wavelength deviates from the selected wavelength, by setting the light of the visible wavelength to the specific wavelength, it is possible to expect a high efficiency to some extent in most of the visible wavelengths.

Here, preferably, by setting the vicinity of the center of the visible wavelength band (a wavelength of about 550 nm) as the specific wavelength, the kinoform 3 having the highest efficiency over the entire visible wavelength can be easily obtained, and the entire visible wavelength range can be easily obtained. The highly efficient light diffuser 1 can be formed throughout.

Further, in the light diffuser 1 according to the present embodiment, the cell 4 made of the kinoform 3 has a predetermined spatial spread with respect to the incident light of a specific wavelength having a predetermined incident angle. It is designed to emit diffracted light.

2 and 3 are conceptual diagrams showing examples of such spatial expansion.

FIG. 2 shows an example of the reflective kinoform 3 (when the surface of the cell 4 is made of a material having light reflectivity) when used as the reflective light diffuser 1, and FIG. An example of a transmissive kinoform 3 when used as the light diffuser 1 (the cell 4 is made of a light-transmissive material)
Is.

In FIG. 2 and FIG. 3, y ₁ is long in the x ₁ direction.
A rectangular region short in the direction is defined as a spatial region in which the diffracted light from the kinoform 3 is distributed.

Therefore, when the observer observes from this region or the angle range corresponding to this region by illuminating with incident light of a specific wavelength having a predetermined incident angle, the light diffuser 1 according to the present embodiment can be seen. The cell 4 in FIG.

On the other hand, since a large number of cells 4 are arranged side by side on the light diffuser 1 according to the present embodiment, the entire light diffuser 1 can be made to appear to shine.

If necessary, each cell 4 may emit diffracted light to different spatial areas on the light diffuser 1.

In any case, since the diffracted light can be concentrated only in a spatial region required according to the use, as in the conventional case described above, omnidirectional diffusion (scattering) or specular reflection light / direct transmission light can be performed. The utilization efficiency of incident light can be made extremely high as compared with the system that occurs.

Furthermore, the spatial region can be designed according to the application, and the light diffuser 1 diffuses widely only in the horizontal direction.
Etc. can be easily manufactured.

Similarly, in the spatial region, the light intensity distribution can be made uniform or the intensity can be locally provided.

That is, when the light intensity distribution is made uniform, when observed from within the corresponding spatial region, it is possible to stably shine and look with the same brightness.

When the intensity is locally increased, the light diffuser 1 appears to have the maximum brightness mainly from the viewpoint to be observed, and the light diffuser 1 appears to be gradually darker when the position of the viewpoint is deviated.
Can be easily realized.

Here, the angle range of the light emitted from the cell 4 is
If it has a spread of 12 ° or more in the horizontal direction,
When using the light diffuser 1 according to the present embodiment for display use, under general display observation conditions,
Both eyes of the observer can be placed within the spatial spread of the emitted light, and an easy-to-see display that does not cause a sense of discomfort due to the brightness difference between the two eyes can be provided.

For example, when an observer at a distance of 300 mm from the light diffuser 1 observes an eye distance of 65 mm between both eyes, the spread in the horizontal direction (direction in which both eyes are lined up) is about 12 °. Required.

Therefore, if there is a spread of 12 ° or more, diffused light can be incident on both eyes of the observer under many observation conditions.

Here, it has been described that the specific wavelength has the above-mentioned effect, but when the illumination light is white light, the diffracted light emitted from the kinoform 3 is slightly different for each wavelength. It is distributed in different spatial areas.

In the light diffuser 1 according to the present embodiment, since the spatial region has a spread, the diffracted light distributions of the respective wavelengths have regions overlapping with each other.

When an observer observes from a region where many wavelengths overlap, it is recognized as white. Therefore, in many applications, it is desirable for the light diffuser 1 to make the overlap region large to some extent. .

Particularly, the angle range of the light emitted from the cell 4 is 3
In the case of a spread of ≧ °, the wavelength distribution of the dominant wavelength of visible light due to diffraction is about 3 ° under general illumination conditions, so the size of the illumination light source generally has a certain size. This helps ensure that a spatial region where the dominant wavelengths of visible light overlap is obtained, and the above-mentioned white observable region can be easily formed.

Further, in the above description, the incident angle of the illumination light is a predetermined incident angle, but the deviation of the incident angle of the illumination light from the predetermined incident angle is
It mainly reflects on the exit angle of the diffracted light from the light diffuser 1.

Therefore, the light diffuser 1 according to the present embodiment can exhibit the same function as the case of a predetermined incident angle with respect to a certain change in the angle of the illumination light.

Further, the kenoform 3 is suitable for mass production by the embossing technology because it is a surface relief type.
In addition to being able to be mass-produced at low cost, it can be made inexpensive, thin and lightweight.

As described above, due to the action of diffractive optics, the emission range (viewing zone) of light can be set arbitrarily, and the ratio of the emitted light into the viewing zone with respect to the incident light can be made extremely high. It is possible to obtain a light diffuser that has a low cost, a thin structure, and a light intensity distribution in the viewing area that can be arbitrarily set, if necessary.

(Second Embodiment: Corresponding to Claim 3, Claim 5, and Claim 6) FIG. 4 is a perspective view showing a configuration example of a light diffuser according to the present embodiment, and FIGS. The same elements as those in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted. Here, only different portions will be described.

That is, as shown in FIG. 4, the light diffuser 1 according to the present embodiment is arranged on the flat substrate 2 in the light diffuser 1 having the structure of the above-described first embodiment. All the cells 4 formed are made of kinoforms 3 having the same phase modulation pattern as each other.

Next, in the light diffuser 1 according to the present embodiment configured as described above, all the cells 4 arranged on the planar substrate 2 have the same phase modulation pattern. Since the kinoform 3 is made of the foam 3, it is only necessary to design the phase distribution of the kinoform 3, and it is possible to arrange the identical kinoforms 3 in a very simple and extremely simple manner. It is possible to manufacture the light diffuser 1 having a property of forming a desired light intensity distribution in a spatial region where the light is diffused.

Also in the manufacturing process, it is relatively easy to arrange a large number of one kinoform, and the light diffuser 1 having a large area can be easily manufactured.

The light diffuser 1 according to the present embodiment shown in FIG.
In FIG. 3, the area where the diffracted light distributions from the cells 4 overlap with each other when illuminated with light of a specific wavelength is shown as a “common diffusion area”.

When it is necessary to recognize the entire light diffuser 1 as shining uniformly during the observation, this common diffusion area should be made large and the area around which it is insufficiently overlapped should be made small. Is desirable.

When the spread area of the diffracted light distribution from one cell 4 is sufficiently larger than the size of the light diffuser 1,
It is possible to recognize that the entire light diffuser 1 shines uniformly while increasing the light use efficiency.

Further, in the light diffuser 1 according to the present embodiment, if the observation distance (corresponding to the position in the z direction) is larger than a certain amount (for example, several times the size of the light diffuser or more),
The angular range of the common diffusion region is kept substantially constant without depending on the observation distance.

Therefore, at any observation distance,
It is possible to obtain an emission light distribution close to a desired light intensity distribution in an emission angle range corresponding to a preset spatial area.

(Third Embodiment: Claims 4 to 6)
FIG. 5 is a perspective view showing a configuration example of the light diffuser according to the present embodiment. The same elements as those in FIGS. 1 to 3 are designated by the same reference numerals, and the description thereof will be omitted. Only the part will be described.

That is, as shown in FIG. 5, the light diffuser 1 according to the present embodiment is predetermined as the kinoform 3 in the light diffuser 1 having the configuration of the above-described first embodiment. The kinoform 3 is used so that the diffracted light emitted from all the cells 4 coincides with the incident light having a specific wavelength at the incident angle in a predefined spatial region.

Next, in the light diffuser 1 according to the present embodiment configured as described above, as the kinoform 3,
By using the kinoform 3 in which the diffracted light emitted from all the cells 4 is matched in a predetermined spatial region with respect to the incident light of a specific wavelength having a predetermined incident angle, The light diffuser that can minimize the light distributed outside the target area and can form the desired light intensity distribution in the predefined spatial area under the condition that the light utilization efficiency is the highest. 1 can be obtained.

Further, when observing from a predefined spatial region, the entire light diffuser 1 can be made to appear to uniformly shine.

The light diffuser 1 according to the present embodiment shown in FIG.
2 shows a state in which light is diffracted into a spatial area (= predefined spatial area) common to each cell 4.

Even when white illumination light is incident on the light diffuser 1 according to the present embodiment, the influence of chromatic dispersion due to diffraction is relatively unlikely to occur in the vicinity of the spatial region defined in advance. When observed from the vicinity of a predefined spatial region, the light diffuser 1 can be made to appear to shine with a certain constant color (a color close to white).

In particular, if the width of the predefined spatial region is larger than the angle of wavelength dispersion due to diffraction with respect to the predefined incident direction of incident light (y direction in FIGS. 2 and 3), A viewpoint in which the light diffuser 1 is observed as white can be formed on the predefined spatial region, and the wider the predefined spatial region is, the more the range (viewing region) of the viewpoint becomes. Can be expanded.

(Fourth Embodiment: Claims 9 to 1)
FIG. 6 is a perspective view showing a configuration example of the display device according to the present embodiment, and the same elements as those in FIGS. 1 to 5 are designated by the same reference numerals.

That is, as shown in FIG. 6, the display device according to the present embodiment is a light diffuser having the configuration of any one of the first to third embodiments described above. 1 is arranged so as to face a rear surface of a transmissive display body 5 such as a liquid crystal display (LCD) panel which controls and displays light transmission, and illumination light is emitted from the rear surface side of the light diffuser 1. It is supposed to be incident.

Next, in the display device according to the present embodiment configured as described above, the light diffusion having the configuration of any one of the first to third embodiments described above is provided. The light diffuser 1 is formed by the function of the light diffuser 1 described above by disposing the body 1 so as to face the back surface of the transmissive display body 5 that controls and displays light transmission. The spatial area of the emitted light due to can be set as the viewing area of the display device, and it is possible to realize the display device in which an extremely bright display image can be observed from the range set as the viewing area.

In this case, similarly, the above-mentioned first to third
With the function of the light diffuser 1 having the configuration of any one of the embodiments, the brightness observed in the range set as the viewing area is made uniform, or the brightness is set as the viewing area. It is possible to suppress the color change within the range.

As described above, it is possible to observe a very bright and high quality display image in an arbitrary viewing area, and it is possible to obtain a thin display device.

(Modification 1) A display device according to this modification is
In the display device having the configuration as shown in FIG. 6, when the transmissive display body 5 has a pixel structure, at least one cell 4 on the light diffuser 1 corresponds to one pixel. I have to.

In the display device according to the present modification configured as described above, when the transmissive display body 5 has a pixel structure, at least one cell 4 on the light diffuser 1 is provided for one pixel. By supporting more than one,
The image displayed by the display device can be observed as a high-quality image without flicker.

(Modification 2) A display device according to this modification is
In the display device having the configuration as shown in FIG. 6, when the transmissive display body 5 has a pixel structure in which RGB is divided for each primary color, one minimum unit pixel (for example, R pixel)
On the other hand, one or more cells 4 on the light diffuser 1 correspond to each other.

Here, particularly when the transmissive display body 5 is composed of the minimum unit pixel for each primary color in this way, the kinoform 3 forming the primary color of each minimum unit pixel and the cell 4 at a position corresponding to the primary color. It is preferable to match a specific wavelength at the time of designing.

In the display device according to the present modification configured as described above, when the transmissive display body 5 has a pixel structure divided into primary colors such as RGB, one minimum unit pixel (for example, R Pixel), cell 4 on the light diffuser 1
Are associated with each other, the viewing zones for the respective primary colors are spatially coincident with each other, and a desired color display image can be observed within the range set as the viewing zone. The light utilization efficiency within the range set as can also be maximized.

When the viewpoint position can be fixed, the color filter or the like on the transmissive display 5 can be omitted, and the loss of light of the wavelength corresponding to each primary color can be reduced. The light utilization efficiency can be further improved.

(Modification 3) In the display device according to the present embodiment, when the illumination light is incident from the transmissive display body 5 side (a reflection type light diffuser is used), the illumination light is emitted from the light diffuser 1.
In any of the cases where the light is incident from the side (using the transmissive light diffuser 1), the light utilization efficiency is high and bright display can be realized.

Further, since external illumination light can be used with high efficiency, it is not necessary to incorporate a light source, and the display device can be made even thinner.

On the other hand, when used as a reflection type display device in which external illumination light is incident from the front surface, the light diffuser 1 is formed of a material having light transmissivity, and the light diffuser 1 is used for controlling light modulation during reflection. When it is arranged on the front surface of a reflection type display body such as a liquid crystal display element for performing display by external light, the external illumination light is emitted to the light diffuser 1 twice (before entering the display body 5 and before exiting from the display body 5). As will be described later, in designing the kinoform 3, the desired wavefront is set to 10 for both such forward and backward light waves.
Although it is difficult to obtain the efficiency of 0%, in the display device according to the present embodiment using the reflection type light diffuser 1,
Since the number of times the light diffuser 1 acts once is 10
An efficiency of 0% can be obtained, and extremely bright display can be performed.

(Fifth Embodiment: Claims 9 to 1)
FIG. 7 is a perspective view showing a configuration example of the display device according to the present embodiment, and the same elements as those in FIGS. 1 to 6 are designated by the same reference numerals.

That is, the display device according to the present embodiment allows the light diffuser 1 having the structure of any one of the first to third embodiments described above to transmit light. It is arranged so as to face the front surface of the transmissive display body 5 such as a liquid crystal display (LCD) panel which is controlled and displayed, and the illumination light is incident from the rear side of the transmissive display body 5. .

Next, also in the display device according to the present embodiment configured as described above, the same operational effect as that of the display device according to the above-described fourth embodiment can be obtained, and in addition, the transmission device is transparent. Since the light emitted from the mold display 5 is diffused, an arbitrary wavefront can be selected for the illumination light incident on the mold display 5, and the performance of the mold display 5 can be maximized. .

For example, when the transmissive display body 5 is a liquid crystal display element, light having a substantially plane wave shape is made incident on the transmissive display body to perform display with maximum contrast and the like. In addition, since the viewing area can be set separately by the function of the light diffuser 1, it is possible to perform extremely high quality display with high light utilization efficiency and high image quality.

(Other Embodiments) The present invention is not limited to the above-described embodiments, but can be variously modified and implemented at the stage of implementation without departing from the spirit thereof. Is. (A) In each of the embodiments, the case where a plurality of cells 4 are arranged in an orthogonal matrix has been described, but the present invention is not limited to this. For example, as shown in FIG. 8, the cells 4 may be arranged in an arbitrary matrix. A configuration in which a plurality of them are arranged may be adopted.

Further, the cell 4 is not limited to the orthogonal matrix shape or the arbitrary matrix shape, and the cells 4 may be arranged randomly, or the cells 4 may be arranged so as to partially overlap with other cells 4. Good.

(B) In each of the embodiments described above, the case where the shape of the cell 4 is a quadrangle has been described. However, the shape of the cell 4 is not limited to this, and other shapes such as a circle and a hexagon may be used. You may do it.

(C) In each of the embodiments described above, the case where the kinoform 3 is a surface relief type has been described, but the invention is not limited to this, and the phase modulation amount can be controlled by the distribution of the refractive index. May be.

In this case, it is possible to form the light diffuser 1 having no unevenness on the surface, and even if the surface of the light diffuser 1 is uniformly coated with an adhesive or the like, It can be handled easily without changing the function significantly,
In particular, it is possible to easily combine and assemble with a flat display element.

When used as the reflection type light diffuser 1, it may be constructed such that a reflection layer is provided on the back surface.

Further, the respective embodiments may be combined as appropriate as much as possible, and in that case, the combined operation and effect can be obtained. Further, the above-described embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent features. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, the problem (at least one) described in the section of the problem to be solved by the invention can be solved, and When the effect (at least one) described in the section can be obtained, a structure in which this constituent element is deleted can be extracted as an invention.

[0120]

As described above, according to the present invention, diffracted light having a predetermined spatial spread is emitted to a flat substrate with respect to incident light of a specific wavelength having a predetermined incident angle. A plurality of cells formed of kinoform having the function of arranging, and the surface of each cell is made of a material having light reflectivity, or each cell is made of a material having light transmittance. With this configuration, it is possible to arbitrarily set the emission range (viewing area) of light by the diffractive optical effect, and it is possible to make the ratio of the exiting light into the viewing area to the incident light extremely high. Thus, it is possible to provide a light diffuser in which the intensity distribution of light within the viewing zone can be arbitrarily set as required.

Further, since the light diffuser of the present invention is combined with the transmissive display, it is possible to observe an extremely bright and high quality display image in any viewing area, and the structure is inexpensive. Therefore, a thin and lightweight display device can be provided.

[Brief description of drawings]

FIG. 1 is a front view showing a first embodiment of a light diffuser according to the present invention.

FIG. 2 is a conceptual diagram showing an example of a reflective kinoform when the light diffuser according to the first embodiment is used as a reflective light diffuser.

FIG. 3 is a conceptual diagram showing an example of a transmissive kinoform when the light diffuser according to the first embodiment is used as a transmissive light diffuser.

FIG. 4 is a perspective view showing a second embodiment of a light diffuser according to the present invention.

FIG. 5 is a perspective view showing a third embodiment of a light diffuser according to the present invention.

FIG. 6 is a perspective view showing a fourth embodiment of a display device according to the present invention.

FIG. 7 is a perspective view showing a fifth embodiment of a display device according to the present invention.

FIG. 8 is a front view showing another embodiment of the light diffuser according to the present invention.

[Explanation of symbols]

1 ... Light diffuser 2 ... Planar substrate 3… Kinoform 4 ... cell 5 ... Transmissive display.

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Claims (11)

[Claims] 1. A reflection type light diffuser for diffusing light, in which diffracted light having a predetermined spatial spread with respect to incident light of a specific wavelength having a predetermined incident angle on a planar substrate. 1. A light diffuser, comprising a plurality of cells formed of kinoform having a function of emitting light, wherein the surface of each cell is made of a material having light reflectivity. 2. A transmissive light diffuser for diffusing light, which is a diffracted light having a predetermined spatial spread with respect to incident light of a specific wavelength having a predetermined incident angle on a planar substrate. 1. A light diffuser, characterized in that a plurality of cells made of kinoform having a function of ejecting are disposed, and each of the cells is made of a light-transmitting material. 3. The light diffuser according to claim 1 or 2, wherein all cells arranged on the planar substrate are made of kinoform having the same phase modulation pattern. A light diffuser characterized by. 4. The light diffuser according to claim 1 or 2, wherein, as the kinoform, an incident light of a specific wavelength having the predetermined incident angle is emitted from all the cells. A light diffuser characterized in that a kinoform is used so that diffracted light is matched in a predefined spatial region. 5. The method according to any one of claims 1 to 4.
The light diffuser according to the item 1, wherein the angular range of the light emitted from each of the cells has a spread of 12 ° or more in the horizontal direction. 6. The method according to any one of claims 1 to 5.
The light diffuser according to the item 1, wherein the angular range of the light emitted from each of the cells has a spread of 3 ° or more. 7. The method according to any one of claims 1 to 6.
The light diffuser according to the item 1, wherein the phase modulation amount on the kinoform is set so that the diffraction efficiency is maximum at a specific wavelength in the visible light band. 8. The method according to any one of claims 1 to 7.
The light diffuser according to the item 1, wherein the kinoform is a surface relief type. 9. The light diffuser according to any one of claims 1 and 3 to 8 is arranged so as to face a back surface of a transmissive display for displaying light by controlling light transmission. A display device comprising: 10. The light diffuser according to any one of claims 2 to 8 is arranged so as to face a back surface or a front surface of a transmissive display body that controls and displays light transmission. A display device characterized by being formed. 11. The display device according to claim 9, wherein when the transmissive display body has a pixel structure, at least one cell on the light diffuser is provided for one pixel. A display device characterized by being adapted to one or more.