JP2002162573A - Spatial optical modulator and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily display images in colors at a high speed. SOLUTION: White light, emitted from a lamp 31, is branched to light beams of three colors: red light, green light and blue light by a volume hologram element 33. These light beams are collected to a GLV 20 by a cylindrical lens 34. The light beams of the respective colors are modulated respectively independently and spatially by the GLV 20 and are made incident via at cylindrical lens 34 on the volume type hologram 33. After the light beams of the three colors have been multiplexed by the volume hologram 33, the light beams are scanned in a prescribed direction by a galvanomirror 35, and the images displayed in colors are projected onto a projection surface 37 via a projection lens 36.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image display device for displaying an image. Further, the present invention relates to a spatial modulator suitable for use in such an image display device.

[0002]

2. Description of the Related Art Conventionally, various display devices for displaying an image by projecting light have been put to practical use. In such a display device, for example, a liquid crystal panel or a DMD (Digital MicromirroDevice) is used as a spatial modulator that modulates light to be projected according to an image to be displayed.

Here, for example, when a display device is configured using a liquid crystal panel, most of the incident light is
Absorption and reflection are caused by the color filters and frames between pixels. For this reason, in order to obtain high luminance, it is necessary to use a light source having a large output, and power consumption increases.

Therefore, each pixel (pixel) of the liquid crystal panel
A method has been proposed which uses a microlens and a volume hologram element in order to make the color-separated light incident on the light source (Applied Optics, Vol. 36, 476).
1,1997). In addition, in order to achieve the same object, a proposal for performing color separation using a diffraction grating (grating) (Applied Optics, Vol. 17, 2273, 1978), and performing color separation using a diffractive optical element Proposal (Applied Optic
s, Vol. 38, 7193, 1999) and (Opt. Lett. 18, 1214, 1993).

It is known that a volume hologram element has higher diffraction efficiency and wavelength resolution than a normal grating or a flat hologram element, and therefore exhibits ideal optical characteristics widely suitable for various uses. . However,
The volume hologram element has low stability of the material itself, and has a problem in stability against thermal expansion and humidity. However, in recent years, material development has progressed due to an increase in interest in technology for forming a memory element using such a volume hologram element, and a volume hologram element exhibiting excellent characteristics that can be widely used practically has been developed. Is being transformed. One of such volume hologram elements is PDA (Phoropolymer with Diffusion Amplificat).
ion) (SPIE Proc., Vol. 3740, 25
8,1999).

In recent years, research and development of diffraction gratings (gratings) that can be freely driven by a micromachine have been advanced. Therefore, a proposal has been made regarding a display device using such a diffraction grating as a spatial modulator that modulates light projected according to a display image, and has attracted attention (US Pat. No. 5,313,360).

[0007] As described above, the micro-machine type diffraction grating used as a spatial modulator is generally called a grating light valve (GLV), and is a liquid crystal such as that conventionally used as a spatial modulator. Compared to panels and DMDs, they can be operated at high speed and can be manufactured at low cost using various semiconductor manufacturing technologies.

Therefore, it is expected that a display device that can display a clear and bright image without a joint can be realized at low cost by configuring the display device using the GLV.

[0009]

By the way, in recent years, G
Although various display devices using an LV as a spatial modulator have been proposed, the GLV performs spatial modulation with a completely different configuration from a liquid crystal panel or a DMD which has been widely used as a spatial modulator. The fact is that a technique for performing image display efficiently and efficiently has not been established.

That is, in a display device using a GLV proposed in the past, the optical system for displaying an image is complicated. Problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional situation, and has as its object to provide an image display device capable of displaying an image in color at high speed and easily. Another object is to provide a spatial modulator suitable for use in such an image display device.

[0012]

A spatial modulator according to the present invention includes a plurality of ribbon arrays each having a plurality of minute ribbons arranged one-dimensionally on a substrate. Each of the ribbons in each of the ribbon rows is independently driven so as to be able to freely move up and down with respect to the main surface of the substrate. Further, each of the ribbon rows is characterized in that light of a different wavelength range is incident thereon and that the incident light is spatially modulated and reflected.

The spatial modulator according to the present invention configured as described above can spatially modulate light of different wavelength ranges by a plurality of one-dimensionally arranged ribbon arrays. Further, the spatial modulator according to the present invention can be manufactured minutely by using various semiconductor manufacturing techniques and can be operated at extremely high speed, so that it can be used as a spatial modulator in an image display device. It can be suitable. Furthermore, the spatial modulator according to the present invention includes a ribbon array for each light in the wavelength range to be modulated, and since these ribbon arrays are integrally provided on the substrate, the spatial modulator is used as a spatial modulator in an image display device. In this case, not only the number of components can be reduced, but also it becomes unnecessary to align the ribbon row for each light in each wavelength range.

An image display device according to the present invention includes a light source, a spatial modulator, a multiplexing mechanism, and a projection mechanism.
The light source emits light in a predetermined wavelength range. In the spatial modulator, light emitted from the light source is one-dimensionally incident for each wavelength range, and a plurality of one-dimensional spatial modulation elements are arranged at incident positions of the respective lights. The resulting light is spatially modulated by each spatial modulation element for each wavelength range. The multiplexing mechanism multiplexes the light modulated for each wavelength range by the spatial modulator and emits the light in a predetermined direction. The projection mechanism displays an image by scanning and projecting the light multiplexed by the multiplexing mechanism in a predetermined direction.

In the image display apparatus according to the present invention having the above-described structure, the one-dimensional spatial modulation element modulates light by the spatial modulator provided for each wavelength range, and the spatial modulator modulates the light. After multiplexing the light modulated for each area, an image is displayed by scanning in a predetermined direction. Therefore, it is easy to independently modulate light for each wavelength range by the one-dimensional spatial modulation element in the spatial modulator. In addition, by using a spatial modulator in which a plurality of one-dimensional spatial modulators are provided, the number of components can be reduced, and the spatial modulators can be positioned for each light in each wavelength range. Can be eliminated.

In the image display device according to the present invention, the spatial modulator is a one-dimensional spatial modulating element, which is a ribbon array in which a plurality of minute ribbons are arranged one-dimensionally on a substrate. It is preferable to use a spatial modulator that includes a plurality of ribbon modulators and that can be moved up and down with respect to the main surface of the substrate by being driven independently of each other. Such a spatial modulator can be manufactured minutely by using various semiconductor manufacturing technologies, and can be operated at an extremely high speed.
Therefore, an image can be displayed with a sufficient amount of information. Further, the configuration of the entire apparatus can be simplified, and the cost can be reduced.

In the image display device according to the present invention, the multiplexing mechanism may include, for example, a volume hologram element,
It can be realized by a planar hologram element, a diffraction grating, a dichroic mirror, or the like. Thus, the light modulated for each wavelength range by the spatial modulator can be combined and emitted in a predetermined direction.

Specifically, for example, the above-mentioned multiplexing mechanism can be realized by a volume hologram element that is multiplex-recorded so that light incident from different directions is combined and emitted in a fixed direction. In addition, for example, the above-described multiplexing mechanism can be realized by a plurality of volume hologram elements that respectively emit light incident from different directions in a certain direction.

In the image display device according to the present invention, since the light use efficiency can be improved by realizing the multiplexing mechanism by the volume hologram element, even when the output from the light source is reduced. In addition, the brightness of an image to be displayed can be improved, and low power consumption and high image quality can be achieved. In addition, by using a volume hologram element, the configuration of the optical system can be simplified, and the size of the entire apparatus can be reduced.
Reliability can be improved.

As such a volume hologram element, for example, PDA (Photopolymer with Diffusion Amplifier)
ification). Thus, the image display device according to the present invention can ensure high diffraction efficiency and wavelength resolution in the spatial modulator, and can display a high-quality image with high accuracy. In addition, it is possible to prevent the spatial modulator from expanding due to heat or to change characteristics due to a change in humidity, and to display an image stably and reliably.

Further, in the image display device according to the present invention, the light source includes a plurality of light source sections each of which emits light of a different wavelength range and which enters the emitted light into a spatial modulation element of the spatial modulator. It is desirable to have. This makes it possible to adjust the color characteristics and the output of each light source unit independently, thereby improving the degree of freedom in device design.

Further, in the image display device according to the present invention, the light emitted from the light source is demultiplexed into light of different wavelength ranges, and the demultiplexed light is incident on the spatial modulation elements of the spatial modulator. A demultiplexing mechanism may be provided. Thus, light in a plurality of wavelength ranges can be obtained using a single light source.

In this case, the demultiplexing mechanism can be realized by, for example, a volume hologram element, a plane hologram element, a diffraction grating, or a dichroic mirror. Thus, light from a single light source can be split and incident on the spatial light modulator.

Specifically, for example, the above-mentioned demultiplexing mechanism is implemented by a volume hologram element multiplexed and recorded so that light incident from a fixed direction is demultiplexed for each wavelength range and emitted in different directions. Can be realized. Further, for example, the above-described demultiplexing mechanism can be realized by a plurality of volume hologram elements that emit light incident from a certain direction in different directions.

In the image display device according to the present invention, since the light use efficiency can be improved by realizing the demultiplexing mechanism by the volume hologram element, even when the output from the light source is reduced. In addition, the brightness of an image to be displayed can be improved, and low power consumption and high image quality can be achieved. In addition, by using a volume hologram element, the configuration of the optical system can be simplified, and the size of the entire apparatus can be reduced.
Reliability can be improved.

As such a volume hologram element, for example, PDA (Photopolymer with Diffusion Amplifier)
ification). Thus, the image display device according to the present invention can ensure high diffraction efficiency and wavelength resolution in the spatial modulator, and can display a high-quality image with high accuracy. In addition, it is possible to prevent the spatial modulator from expanding due to heat or to change characteristics due to a change in humidity, and to display an image stably and reliably.

Furthermore, in the image display device according to the present invention, for example, by adopting the following configuration,
Images can be displayed in color. That is, each spatial modulation element of the spatial modulator is configured to modulate light corresponding to a different region in an image to be displayed. Also,
The projection mechanism is configured to project the light modulated by each spatial modulation element of the spatial modulator to a different position for each wavelength range, and to adjust the position where each light is projected to sequentially scan. Thereby, the color-displayed image can be displayed as a whole.

[0028]

Embodiments of the present invention will be described below in detail with reference to the drawings.

The wavelength converter according to the present invention includes a plurality of ribbon rows on which a plurality of minute ribbons are arranged one-dimensionally on a substrate, and light of different wavelength ranges is incident on each ribbon row. Thus, one of the features is that incident light is spatially modulated and reflected. Specifically, a micro-machine type diffraction grating can be used as such a spatial modulator. When a micro-machine type diffraction grating is used as a spatial modulator, it is generally used as a grating light valve (GLV).
t Bulb).

Therefore, the principle of the present invention will be described below before describing the embodiment of the present invention.

A GLV is formed by forming a plurality of minute ribbons on a substrate by various semiconductor manufacturing techniques. Each ribbon can be freely raised or lowered by a piezoelectric element or the like. In the GLV configured as described above, each ribbon is dynamically driven in height, and is irradiated with light in a predetermined wavelength range, thereby forming a phase type diffraction grating (grating) as a whole.
That is, GLV is ± 1 due to light irradiation.
The next (or higher) diffracted light is generated.

Therefore, by irradiating such a GLV with light and blocking the 0th-order diffracted light, the GLV can be obtained.
By driving each of the ribbons up and down, the diffracted light blinks, whereby an image can be displayed.

Conventionally, various display devices have been proposed which display images using the above-described characteristics of the GLV. In a conventional display device, when displaying a structural unit (hereinafter, referred to as a pixel) of a planar image to be displayed, one pixel is displayed with about six ribbons. In a set of ribbons corresponding to one pixel, adjacent ribbons are alternately raised or lowered.

However, if the ribbons in the GLV can be independently wired and driven independently, an arbitrary one-dimensional phase distribution can be generated.
The GLV thus configured can be considered as a reflection type one-dimensional phase type spatial modulator.

Therefore, as the spatial modulator in the present invention, a GLV configured as a reflective one-dimensional phase spatial modulator as described above can be used. That is, as shown in FIG. 1, for example, each of the ribbons 11 of the GLV 10 is independently driven to generate an arbitrary phase distribution. Light of a predetermined wavelength region having the same phase is incident on the GLV 10 as shown by an arrow in FIG. 1, and the incident light is modulated and reflected. As shown in FIG. A one-dimensional wavefront can be generated.

The spatial modulator according to the present invention is constructed by using a plurality of ribbon rows each having a one-dimensionally arranged ribbon for each light in the incident wavelength region by utilizing such a principle. It is characterized by having. Thus, a GLV 20 as shown in FIG. 3 will be described below as a specific configuration example of the spatial modulator according to the present invention.

The GLV 20 is, as shown in FIG.
A plurality of minute ribbons 22 are formed on one. Each of the ribbons 22 includes a driving unit 23 including a driving electric circuit, wiring, and the like, and is driven by the driving unit 23 so as to be able to move up and down with respect to the main surface of the substrate 21.

In the GLV 20, each ribbon 22
Are one-dimensionally arranged to form a ribbon row. A plurality of ribbon rows are provided for each wavelength range of incident light. Specifically, for example, in the example shown in FIG.
The GLV 20 is configured so that light of three colors, red light, green light, and blue light, is incident thereon, and a red ribbon row 24r and a green ribbon row 24g are respectively provided at positions where these lights are incident. , The raw food ribbon rows 24b are arranged side by side at positions parallel to each other. In the following, these ribbon rows 24r, 24g, 24b are collectively referred to simply as the ribbon row 24.

Then, each ribbon row 24 is
Can be driven independently, and can generate an arbitrary phase distribution as described with reference to FIGS. 1 and 2, respectively. Accordingly, the GLV 20 independently receives the red light, the green light, and the blue light by using the red ribbon row 24r, the green ribbon row 24g, and the raw food ribbon row 24b for each color independently. One-dimensional wavefronts can be generated.

The GLV 20 configured as described above can be manufactured minutely using various semiconductor manufacturing techniques, and can be operated at extremely high speed. Therefore, for example, it can be suitable for use as a spatial modulator in an image display device. Also, GLV20 is
A ribbon array 24 is provided for each light in the wavelength range to be converted, and since the ribbon arrays 24 are integrally provided on the substrate 21, the number of components is reduced when used as a spatial modulator in an image display device. In addition, it is not necessary to align the ribbon row for each light in each wavelength range.

In the above description, the GLV 20
Are three colors of light, red light, green light, and blue light, and three ribbon rows 24 corresponding to these lights, respectively.
It is said to have. However, the spatial modulator according to the present invention is not limited to having three ribbon rows, and may have a number of ribbon rows corresponding to the number of incident lights.

In the above description, the GLV 20
States that the ribbon rows 24 are arranged side by side at positions parallel to each other. However, the spatial modulator according to the present invention is not limited to the arrangement position of each ribbon row.

Specifically, for example, as shown in FIG.
The red ribbon row 24r, the green ribbon row 24g, and the blue ribbon row 24b are arranged one-dimensionally (linearly).
Light corresponding to each ribbon row 24 may be incident on each position. However, in this case, the size of the GLV 20 itself becomes larger in the horizontal direction in the figure as compared with the case where the GLVs 20 are disposed at positions parallel to each other as shown in FIG. However, there is a fear that the size and size will be complicated and large.

For example, as shown in FIG. 5, a plurality of ribbons 22 are arranged one-dimensionally (linearly), and a ribbon 22r corresponding to red light, a ribbon 22g corresponding to green light,
Ribbons 22b corresponding to blue light may be sequentially arranged. That is, this case corresponds to a case where the ribbon rows 24 corresponding to the respective colors are arranged in a so-called “nested structure”. The G on which each ribbon 22 is disposed in this manner
When the LV20 is used as a spatial modulator in an image display device, for example, a microlens array or various hologram elements are used to form each color in the same manner as in the case where each color light is incident on a conventionally used liquid crystal panel. Light can be incident on the corresponding ribbons 22. However, in this case, compared to the case shown in FIG. 3, there is a possibility that the optical system becomes complicated and large.

Next, a display device 30 as shown in FIG. 6 will be described as one configuration example of the image display device according to the present invention. The display device 30 is a device that displays an image by scanning and projecting the light modulated by the spatial modulator. Hereinafter, a case where the above-described GLV 20 is used as the spatial modulator in the display device 30 will be described.

As shown in FIG. 6, the display device 30 includes a lamp 31 for emitting white light as a light source for emitting light in a predetermined wavelength range. The display device 30 is not limited to using the lamp 31 as a light source. For example, a light emitting diode, a semiconductor laser oscillator, or the like may be used as a light source, or natural light introduced from outside may be used as a light source. May be used.

The display device 30 includes a collimator lens 32, a volume hologram element 33, and a cylindrical lens 34 on the optical path of the light emitted from the lamp 31.
And a GLV 20.

The light emitted from the lamp 31 is incident on the collimator lens 32 and is incident on the volume hologram element 33 as parallel light.

The volume hologram element 33 receives the light collimated by the collimator lens 32 and separates the light into predetermined wavelength ranges to form cylindrical light as red light, green light and blue light. The light enters the lens 34. The volume hologram element 33 is, for example, a volume hologram element in which red light, green light, and blue light are multiplex-recorded so as to be diffracted and emitted at different angles, and light of each color is converted into parallel light. As it is, they are emitted at different angles.

The cylindrical lens 34 condenses the red light, green light, and blue light split by the volume hologram element 33, respectively, as shown in FIG.
V20 red ribbon row 24r, green ribbon row 24
g and the blue ribbon row 24b.

The GLV 20 converts the three colors of incident light into a red ribbon row 24r, a green ribbon row 24g,
And spatially modulated by the blue ribbon row 24b and reflected as an arbitrary one-dimensional wavefront. That is, GLV
Reference numeral 20 functions as a spatial modulator in the display device 30.

The display device 30 is configured so that the light reflected by the GLV 20 is again incident on the cylindrical lens 34 and the volume hologram element 33.

That is, the red light, the green light, and the blue light, each of which has been spatially modulated independently by the GLV 20, are collimated by the cylindrical lens 34 and are incident on the volume hologram element 33. Then, the volume hologram element 33 multiplexes the incident red light, green light, and blue light and emits them. At this time, the volume hologram element 33 diffracts the three colors of light incident from the cylindrical lens 34 in the same direction, as is clear from the contrast with the incident light from the collimator lens 32 side. The three colors of light are combined and emitted in a certain direction. Therefore, in the display device 30, by sufficiently correcting the chromatic aberration, the volume hologram element 3
3 enables the combined light to be handled by the same optical system.

Therefore, the display device 30 includes a galvanometer mirror 35 and a projection lens 36 on the optical path of the light emitted from the volume hologram element 33.

The galvanometer mirror 35 is rotatable, for example, in a direction indicated by an arrow A in FIG. 6, and reflects incident light to scan in a direction indicated by an arrow B in FIG. Then, the display device 30 displays an image on the projection surface 37 by projecting the light scanned by the galvanometer mirror 35 through the projection lens 36. That is, in the display device 30, the galvanometer mirror 35 and the projection lens 36 function as a projection mechanism that scans and forms light constituting an image in a predetermined direction.

The display device 30 is not limited to scanning light in a predetermined direction by the galvanometer mirror 35. For example, scanning may be performed by using a mirror array, a polygon mirror, or the like. Scanning may be performed using various diffraction gratings such as a volume hologram element and a flat hologram element. Also, for example, the scanning is not limited to scanning only in the direction perpendicular to the one-dimensionally modulated wavefront, and scanning may be performed two-dimensionally in the vertical and horizontal directions.

The display device 30 configured as described above is
The GLV 20 modulates red light, green light, and blue light for each wavelength range, multiplexes the modulated lights, and scans in a predetermined direction to display an image. Therefore, it is possible to easily modulate the light by using the light for each wavelength range. Further, the display device 30 uses the GLV 20 in which the red ribbon row 24r, the green ribbon row 24g, and the blue ribbon row 24b are integrally formed on a substrate as a spatial modulator. In addition to the reduction, it is not necessary to perform the alignment of the optical system for each light in each wavelength range.

As shown in FIG. 3, the GLV 20 used as a spatial modulator in the display device 30 has ribbon rows 24 corresponding to three colors of red light, green light, and blue light which are parallel to each other. However, the present invention is not limited to the use of a device arranged at a certain position. In the display device 30, for example, as shown in FIG. 4, a GLV 20 in which ribbon rows 24 corresponding to light of three colors are linearly arranged may be used, or as shown in FIG. The GLV 20 in which the ribbons 22 corresponding to the three colors of light are sequentially arranged may be used. However, in this case, there is a possibility that the optical system becomes complicated and large in size as compared with the case where the GLV 20 in which the ribbon rows 24 are provided as shown in FIG.

Such a GLV 20 can be manufactured minutely by using various semiconductor manufacturing techniques, and can be operated at an extremely high speed. Therefore, the display device 30 can display an image with a sufficiently large amount of information by using the GLV 20 as a spatial modulator. Further, the configuration of the entire apparatus can be simplified, and the cost can be reduced.

Further, since the GLV can drive each ribbon in an analog manner, of the incident light,
Light in a predetermined wavelength range can be selectively diffracted. Therefore, in the display device 30, for example, as shown in FIG. 8, a GLV 20 including a single ribbon row 24 can be used as a spatial modulator.

In this case, the single ribbon row 24 in the GLV 20 is operated at a high speed to operate at a high speed so as to sequentially and selectively diffract light in a predetermined wavelength range. Thereby, for example, three colors of light of red light, green light, and blue light are spatially modulated with time shift,
By combining these three colors of light on the projection surface 37, a color-displayed image can be projected.

However, in this case, if a light source that continuously emits light, such as a white light lamp, is used as the light source in the display device 30, the light utilization efficiency of the light source is reduced by 1 / time. 3, the brightness of the displayed image may be reduced.

In the display device 30, the GLV2
It is not limited to using 0 as a spatial modulator, and if a one-dimensional type spatial modulator can be configured to modulate light by a spatial modulator arranged for each wavelength band, various A spatial modulator can be used. As such a spatial modulator, besides GLV, for example,
A shutter array using PLZT (hereinafter, referred to as a PLZT shutter array) can be used.

Since the PLZT shutter array can be operated at a very high speed similarly to the GLV, it can be used as a spatial modulator in the display device 30, thereby realizing color display of an image. . However, while the GLV is a reflection-type spatial modulator, the PLZT shutter array is generally used as a transmission-type spatial modulator. It is desirable that the optical system of the display device 30 be appropriately modified.

By the way, in the display device 30 described above, the white light from the lamp 31 is applied to the volume hologram element 3.
The light is demultiplexed into three colors by 3, and the demultiplexed light is condensed by a cylindrical lens 34 and is incident on the ribbon row 24 of the GLV 20. The three colors of light modulated by the GLV 20 are converted into parallel lights by the cylindrical lens 34, and the three colors of parallel light are combined by the volume hologram element 33 and emitted in a certain direction. That is, in the display device 30, the volume hologram element 33 and the cylindrical lens 34
The light emitted from the light source (lamp 31) is split into light of different wavelength ranges, and the split light is converted into a spatial light modulator (GL).
V20) has a function as a demultiplexing mechanism for making each of the light beams enter the spatial modulation element (ribbon row 24).
It has a function as a multiplexing mechanism that multiplexes light modulated for each wavelength range by the spatial modulator (GLV20) and emits the light in a predetermined direction.

Such a multiplexing mechanism or a demultiplexing mechanism is not limited to being constituted by a combination of the volume hologram element 33 and the cylindrical lens 34. For example, a volume hologram element, a planar hologram It may be constituted by an element, various diffraction gratings, or a dichroic mirror. Therefore, the multiplexing mechanism and the demultiplexing mechanism in the display device 30 will be described below.

In the display device 30, the multiplexing mechanism and the demultiplexing mechanism can be configured using various types of diffraction gratings (gratings) or planar hologram elements in addition to using the volume hologram element 33. . For example, when a normal relief type diffraction grating is used as a multiplexing mechanism or a demultiplexing mechanism, the diffraction efficiency is reduced depending on the wavelength of light, so that it is necessary to adjust the shape and depth of the grating. There is.

Here, a case is considered in which light having a wavelength of λ is incident on a hologram element or a diffraction grating having a grating pitch of 考 え る. At this time, the incident angle of light is Θ
And the emission angle is Ψ, the relationship shown in the following equation 1 is established.

SinΘ-sinΨ = mλ / Λ (Equation 1) In the following, first, a plane diffraction grating having a diffraction order m = 1 will be considered. In the case of a plane hologram element,
The diffraction order m may be an integer of 2 or more, or -1 or less.

It is assumed that light of three colors having wavelengths of λ ₁ , λ ₂ , and λ ₃ is incident on the planar diffraction grating, and the incident angle of each light is Θ _i (i = 1, 2). , 3),
Let the emission angle be _{ｉ i} (i = 1, 2, 3). In this case, the following equations 2 to 4 hold.

[0071] _{sinΘ 1 -sinΨ 1 = λ 1 /} Λ ··· ( Equation _{2) sinΘ 2 -sinΨ 2 = λ} 2 / Λ ··· ( Equation _{3) sinΘ 3 -sinΨ 3 = λ} 3 / Λ ··· (Equation 4) At this time, these three colors of light are
When 4 of the focal length is f, is condensed from the optical axis to a position spaced Ftanpusai _i on GLV 20.. Therefore, in the GLV 20, the ribbon rows 24 corresponding to these three colors of light are arranged at positions corresponding to the respective lights.

Here, the light source of the display device 30 (the lamp 3
When the light emitted from 1) is white light, Θ = Θ
_i (i = 1, 2, 3). At this time,
Grating pitch Λ = 1 μm (ie, 1000 gratings / m
m), and approximating sinΨ = Ψ, the following equations 5 and 6 hold.

Ψ ₁ −Ψ ₂ = λ ₂ −λ ₁ (Equation 5) Ψ ₂ −Ψ ₃ = λ ₃ −λ ₂ (Equation 6) Here, the light of each of the three colors has a wavelength. λ ₁ = 0.46 μm
Blue light, wavelength λ ₂ = 0.52 μm green light, wavelength λ ₃
= 0.64 μm red light, cylindrical lens 3
Assuming that the focal length of No. 4 is f = 10 mm, the distance between the red ribbon row 24r and the green ribbon row 24g in the GLV 20 is 1.2 mm, and the distance between the green ribbon row 24g and the blue ribbon row 24b is 600 μm. You can see what you need to do. By setting each ribbon row 24 in the GLV 20 to this interval, the arrangement position of the GLV 20 is adjusted within the focal plane of the cylindrical lens 34, so that light of three colors can be incident on the corresponding ribbon rows 24 respectively. .

However, when a planar diffraction grating is used as the multiplexing mechanism or the demultiplexing mechanism, since the 0th or higher order diffracted light is generated, the GLV 20 is disposed so that the diffracted light does not become stray light. It is desirable to adjust the position.

Considering the use of a blazed diffraction grating as a multiplexing or demultiplexing mechanism, for example, the incident angle of light is Θ ₁ , the refractive index is n, the center wavelength is λ ₀ , and the wavelength used is λ. , K, the diffraction efficiency η _k of the diffracted light of the k-th order satisfies the relationship shown in the following Expression 7. η _k = [sin [π (k−φ ₀ )] / π (k−φ ₀ )] ² (Expression 7) where φ ₀ in Expression 7 is a value represented by Expression 8 below. It is. φ ₀ = λ ₀ [(n ² −sin ² _{１ 1} ) ^1/2 −cosΘ ₁ ] / λ (n−1) (Equation 8) Here, blazed diffraction is used as a multiplexing mechanism or a demultiplexing mechanism. In the case where a grating is used, the order k of the diffracted light is k = 1, λ ₀
FIG. 9 shows the relationship between 0.55 μm, the refractive index n = 1.5, the diffraction efficiency η ₁ when the light is vertically incident, and the used wavelength λ. As is clear from the results shown in FIG. 9, the blazed diffraction grating has a wavelength of 0.46 μm each.
m, 0.52 μm, and 0.64 μm for blue, green, and red light, respectively, approximately 88%,
It can be seen that diffraction efficiencies of 99% and 94% can be obtained.

Considering the case where a volume hologram element is used as a multiplexing mechanism or a demultiplexing mechanism, even when a hologram of this volume hologram element is recorded by interference between plane waves, the direction of the lattice vector does not change. It is important to consider phase matching. In the volume hologram element, when light is incident from a direction different from that at the time of recording the hologram, or when light of a different wavelength from that at the time of recording is incident, phase mismatch occurs, and the diffraction efficiency may be reduced. Occurs. In addition, by changing the phase mismatch for different wavelengths by changing the incident angle of the incident light at each wavelength, the phase mismatch occurs even when diffracting in the same direction.

More specifically, for example, as shown in FIG. 10, at the time of recording a hologram, light of three colors having different wavelengths is recorded by lattice vectors indicated by arrows w ₁ , w ₂ , and w ₃ in FIG. Considering the case where, when performing reproduction by applying a light having a different lattice vector that during recording, that is, the phase in the light reproduced by the grating vector indicated by an arrow r _1, r _2, r ₃ in FIG. 10 Mismatch occurs. In addition, FIG.
FIG. 3 is a diagram illustrating phase mismatch for light of each wavelength in k-space. Therefore, when a multiplexing mechanism or a demultiplexing mechanism is constituted by a single volume hologram element 33, it is important to record a hologram in consideration of the phase mismatch.

Therefore, instead of forming the multiplexing mechanism or the demultiplexing mechanism by a single volume hologram element 33, for example, as shown in FIG. 11, a plurality of volume hologram elements 33a and 33b are stacked. , A multiplexing mechanism or a demultiplexing mechanism. That is, for example, with diffracts the red light W _R by the first volume hologram element 33a, diffracts the blue light W _B in the same direction as the red light W _R by the second volume hologram element 33b. Further, the first and second volume hologram element 33a, 33b causes the transmitted straight without being diffracted green light W _G, so as to be emitted in the same direction as the red light W _R. Thus, each volume hologram element 33a,
A multiplexing mechanism or a demultiplexing mechanism may be configured by selectively diffracting light in a specific wavelength range at 33b.

[0079] In the display device 30, as shown in FIG. 12, by multiple recording of holograms on a single volume hologram element 33, the blue light _{W B,} the red light _{W R,} and the green light _{W G} May be emitted in the same direction. Normally, the hologram element recorded by multiplexing has a diffraction efficiency that is inversely proportional to the square of the multiplicity. However, a sufficiently high diffraction efficiency can be obtained by forming the volume hologram element 33 from a recording material having a large refractive index fluctuation width.

Further, in the display device 30, the transmission type hologram element is not limited to being used as a multiplexing mechanism or a demultiplexing mechanism. You may.

In the above description of the display device 30, the light converted into parallel light by the volume hologram element 33 is focused on the GLV 20, and the light reflected from the GLV 20 is incident on the volume hologram element 33 again. For this purpose, a cylindrical lens 34 is used. That is, this cylindrical lens 34
It has the function of condensing light on the LV20 and GLV
It has the function of collimating the reflected light from 20 within a one-dimensional plane.

In the display device 30, the above-described function may be realized by a single cylindrical lens 34, or may be realized by a combination of a plurality of lenses in order to suppress chromatic aberration generated in three colors of light. Good. Also,
The present invention is not limited to the use of the cylindrical lens 34, and may be realized by various optical lenses such as a diffraction lens, a gradient index lens, and a Fresnel lens.

In the display device 30, as shown in FIG. 6, a volume hologram element 33 is disposed on a front focal plane of a cylindrical lens 34, and a GLV is provided on a rear focal plane.
When the 20 is provided, the volume hologram element 33
It is desirable to provide an aperture corresponding to the shape of the GLV 20. Thereby, generation of unnecessary stray light can be prevented.

The display device 30 is not limited to realizing the above-described functions using the cylindrical lens 34, and may use, for example, a convex lens instead of the cylindrical lens 34.

In the case where the cylindrical lens 34 is used, as shown in FIG. 13, the light incident on the incident side slit is substantially parallel light having a high aspect ratio. However, as shown in FIG. 14, when the convex lens 40 is used, light is collected also in the Y-axis direction in FIG.
It is necessary to condense substantially parallel light having a high aspect ratio to the focal point of the convex lens 40 in a plane including the Y axis by a cylindrical lens. As is clear from FIGS. 13 and 14, in any case, geometric optics are the same in a plane including the X axis. 13 and 14.
In (2), incident light is made to overlap on the focal plane of the cylindrical lens 33 and the focal plane of the convex lens 40. This is in consideration of optically multiplexing light of three colors, red light, green light, and blue light.

In the display device 30, it is necessary to remove the zero-order light generated by the GLV 20.
Because the color lights are multiplexed, for example, by disposing a filter for removing the zero-order light in the optical system after the multiplexing,
With one filter, zero-order light can be removed for three colors of light.

Next, a display device 50 as shown in FIG. 15 will be described as another configuration example of the image display device according to the present invention. In the following description, only differences from the above-described display device 30 will be described, and portions that are the same as or equivalent to the display device 30 will be given the same reference numerals as in FIG.

As shown in FIG. 15, the display device 50 includes a first laser oscillator 51r and a second laser oscillator 5r as light sources for emitting red light, green light, and blue light, respectively.
1g and a third laser oscillator 51b. In the following description, the first to third laser oscillators 51r, 51g, 51b are collectively referred to simply as the laser oscillator 51.

These laser oscillators 51 may be constituted by semiconductor laser elements which emit light of each color, or may be constituted by laser oscillators which emit laser light of each color by performing wavelength conversion with a nonlinear optical crystal, for example. May be. Further, in the display device 50, instead of the laser oscillator 51, a light source may be configured by light-emitting diodes that emit light of three colors, respectively.

In the display device 50, the red collimator lens 52 r and the green collimator lens 5 r are placed on the optical path of the light emitted by each laser oscillator 51, respectively.
2g and a blue collimator lens 52b. Note that these collimator lenses are collectively referred to simply as a collimator lens 52. The collimator lens 52 converts the light emitted from each of the laser oscillators 51 into parallel light, and enters the cylindrical lens 34. The light incident on the cylindrical lens 34 is
The light is focused on the GLV 20 by the cylindrical lens.

That is, unlike the display device 30 described above, the display device 50 does not use light from a single light source,
A light source that emits light of each color independently is provided.
Further, the display device 50 is configured so that the light emitted by each laser oscillator 51 is directly incident on the cylindrical lens 34 via the collimator lens 52. That is, the display device 50 is configured without the branching mechanism realized by the volume hologram element 33 in the display device 30.

In the display device 50, the light modulated and reflected by the GLV 20 is again incident on the cylindrical lens 34, and is converted into parallel light by the cylindrical lens 34. Then, a first volume hologram element 33a and a second volume hologram element 33b are provided on the optical path of the light converted into parallel light by the cylindrical lens 34.

The first and second volume hologram elements 33a and 33b function in the same manner as described with reference to FIG. 11, and multiplex light of three colors modulated by the GLV 20 and emit the light in a certain direction. That is, in the display device 50, it can be said that the first and second volume hologram elements 33a and 33b constitute a multiplexing mechanism.

The lights combined by the first and second volume hologram elements 33a and 33b are scanned in a predetermined direction by a galvanometer mirror 35 and projected on a projection surface 37 via a projection lens 36. . Thus, the display device 50 is configured to display an image displayed in color on the projection surface 37.

Next, as still another configuration example of the image display device according to the present invention, a display device 60 as shown in FIG.
Will be described. The display device 60 functions as a multiplexing mechanism and a demultiplexing mechanism realized by the volume hologram element 33 and the cylindrical lens 34 in the above-described display device 30 by the first and second dichroic mirrors 61a and 61b. And the cylindrical lens 34. Therefore, in the following description, the description of the same or equivalent parts as the above-described display device 30 will be omitted, and the same reference numerals as those in FIG. 6 will be used.

In the display device 60, as shown in FIG. 16, the white light emitted from the lamp 31 is collimated by the collimator lens 32 and then enters the first dichroic mirror 61a. The first dichroic mirror 61a separates the incident white light into light of three colors, red light, green light, and blue light, and enters the cylindrical lens 34.

In the display device 60, the GLV2
After the light modulated by 0 is converted into parallel light by the cylindrical lens 34, the light enters the second dichroic mirror 61b. Second dichroic mirror 6
1 b multiplexes the three colors of light that have entered and emits them in the same direction, and makes the light enter the galvanomirror 35.

As described above, in the display device 60, by combining the first and second dichroic mirrors 61a and 61b and the cylindrical lens 34, a multiplexing mechanism and a demultiplexing mechanism are realized.

In the above description, the case where the multiplexing mechanism is realized by optically configuring the multiplexing mechanism has been described. That is, an image is displayed in color by scanning in a predetermined direction after multiplexing three colors of light by a multiplexing mechanism. However, in the image display device according to the present invention, by using a spatial modulator capable of operating at a high speed, such as a GLV or a PLZT shutter array, an image can be formed using the afterimage effect of the human eye. Color display may be used. Hereinafter, this case will be described.

In this case, for example, when the character “A” is displayed in color, as shown in FIG.
The character “A” is decomposed into three colors of red, green, and blue, and light of a wavefront corresponding to each color is modulated by each ribbon row in the GLV 20. Then, as shown in FIG. 18, a one-dimensional wavefront separated into each color is sequentially projected by a scanning mechanism such as a galvanometer mirror 35, for example. At this time, it is assumed that the one-dimensional wavefront to be projected is scanned at equal intervals, and each wavefront separated into three colors of red, green and blue is sequentially projected at predetermined time intervals. FIG. 18 shows, for each scanning line, how the wavefronts of the three colors of red, green, and blue are displayed in the same region at each predetermined time. In FIG. 18, the wavefronts of the three colors are collectively shown at different positions.
The red, green, and blue wavefronts are displayed in the same image area. That is, for example, at time t
In = t _3, indicating that the wavefront of the three colors, say appear in the scan line adjacent respectively.

The display apparatus performs such scanning at a sufficiently high speed, and utilizes the afterimage effect of the human eye to perform the scanning.
The red, green, and blue wavefronts can be combined and recognized as a color-displayed image. When the display device projects the wavefront of each color onto different scanning lines, for example, the display device temporarily stores display data of each scanning line in various memories, and sequentially stores the display data in time. What is necessary is just to shift and project and display.

However, each ribbon row 2 in the GLV 20
As described above, it is necessary to arrange the ribbon rows 4 at predetermined intervals according to the position of the incident light.
The interval of 4 and the interval of the scanning line cannot always be matched. In this case, for example, as the wavefront projected and displayed at the same time, a blue wavefront is projected on the [n] th scan line, and a green wavefront is projected on the [n + m] th scan line. For example, by projecting a red wavefront onto the [n + 2m] columns of scanning lines, the scanning may be performed by projecting the wavefronts of the respective colors not at adjacent scanning lines but at positions separated by an integral multiple of the scanning lines.

In this way, when the wavefronts of the respective colors are projected onto different scanning lines to be combined and displayed in color,
Although it is necessary to manufacture each ribbon row 24 in the GLV 20 so as to be an integral multiple of the scanning line, the GLV 20 can be manufactured with extremely high positional accuracy using various semiconductor manufacturing techniques. Also, in order to display all three color wavefronts at the upper end and the lower end of the display area, it is necessary to scan a slightly extra scan line at the upper end and the lower end.

As described above, it is possible to simplify the optical system by realizing the multiplexing mechanism by sequentially scanning the wavefronts of the respective colors sequentially without using the optical multiplexing mechanism. Becomes However, if the timing of displaying the wavefront of each color is shifted, a color shift occurs in the displayed image, so that it is necessary to adjust the scanning timing with high precision. Further, in order to display the wavefronts of the respective colors with a time lag, it is necessary to provide a data buffer mechanism with a memory or the like, and a device for signal processing is required.

The image display device according to the present invention is not limited to the above-described configuration, and it goes without saying that various changes can be made without departing from the spirit of the present invention. According to the present invention, for example, a front-projection image display device, a rear-projection image display device, and the like can be easily realized. And an on-vehicle image display device that projects and displays images on windshields of various vehicles.

[0106]

The spatial modulator according to the present invention can spatially modulate light of different wavelength ranges by a plurality of one-dimensionally arranged ribbon rows. Further, the spatial modulator according to the present invention can be manufactured minutely by using various semiconductor manufacturing techniques and can be operated at extremely high speed, so that it can be used as a spatial modulator in an image display device. It can be suitable. further,
The spatial modulator according to the present invention includes a ribbon array for each light in the wavelength region to be modulated, and since the ribbon arrays are integrally provided on a substrate, the spatial modulator is used as a spatial modulator in an image display device. In addition, not only can the number of components be reduced, but also it is not necessary to align the ribbon row for each light in each wavelength range. Therefore, the spatial modulator according to the present invention can be particularly suitable for use as a spatial modulator in an image display device, and greatly contributes to the realization of an image display device capable of displaying an image in color. It becomes possible.

Further, in the image display device according to the present invention, light is modulated by a spatial modulator in which a one-dimensional spatial modulation element is arranged for each wavelength band, and modulated by the spatial modulator for each wavelength band. After the combined lights are combined, scanning is performed in a predetermined direction to display an image. Therefore, it is easy to independently modulate light for each wavelength range by the one-dimensional spatial modulation element in the spatial modulator. In addition, by using a spatial modulator in which a plurality of one-dimensional spatial modulators are provided, the number of components can be reduced, and the spatial modulators can be positioned for each light in each wavelength range. Can be eliminated. Therefore, according to the image display device of the present invention, an image can be displayed in color at high speed with a simple device configuration.

[Brief description of the drawings]

FIG. 1 shows a GLV which is an example of a spatial modulator according to the present invention.
FIG. 4 is a schematic diagram showing a state in which light is incident on the light emitting device.

FIG. 2 shows a GLV which is an example of a spatial modulator according to the present invention.
FIG. 4 is a schematic diagram showing a state in which light incident on the light is modulated and reflected.

FIG. 3 shows GL as an example of a spatial modulator according to the present invention.
FIG. 5 is a plan view showing a case where three ribbon rows are arranged in parallel in V.

FIG. 4 shows GL as an example of a spatial modulator according to the present invention.
FIG. 5 is a plan view showing a case where three ribbon rows are arranged in a straight line at V.

FIG. 5 shows GL as an example of a spatial modulator according to the present invention.
FIG. 5 is a plan view showing a case where ribbons corresponding to respective colors are sequentially arranged in a straight line at V.

FIG. 6 is a schematic diagram of a display device shown as one configuration example of an image display device according to the present invention.

FIG. 7 is a schematic perspective view showing a state in which a cylindrical lens causes light of three colors to enter a GLV in the display device.

FIG. 8 is a plan view showing a configuration example of a GLV used in the display device.

FIG. 9 is a schematic diagram showing an example of a wavelength after incidence and diffraction efficiency when a blazed diffraction grating is used as a multiplexing mechanism or a demultiplexing mechanism in the display device.

FIG. 10 is a diagram illustrating a phase mismatch that occurs when a volume hologram element is used as a multiplexing mechanism or a demultiplexing mechanism in the display device, and illustrates phase mismatch for light of each wavelength in k-space. FIG.

FIG. 11 is a schematic diagram illustrating a case where a multiplexing mechanism or a demultiplexing mechanism in the display device is realized by a plurality of volume hologram elements.

FIG. 12 is a schematic diagram illustrating a case where a multiplexing mechanism or a demultiplexing mechanism in the display device is realized by a single volume hologram element.

FIG. 13 is a schematic diagram illustrating an optical system of a cylindrical lens used in the display device.

FIG. 14 is a schematic diagram illustrating an optical system of the convex lens when a convex lens is used instead of a cylindrical lens in the display device.

FIG. 15 is a schematic diagram of a display device shown as another configuration example of the image display device according to the present invention.

FIG. 16 is a schematic diagram of a display device shown as still another configuration example of the image display device according to the present invention.

FIG. 17 is a diagram illustrating a case where the multiplexing mechanism in the image display device according to the present invention is realized by devising a scanning method without using an optical system.
FIG. 5 is a schematic diagram illustrating color separation into colors.

FIG. 18 is a diagram illustrating a case where a multiplexing mechanism in the image display device according to the present invention is realized by devising a scanning method without using an optical system. It is a schematic diagram which shows a wavefront according to time.

[Explanation of symbols]

20 GLV, 21 substrate, 22 ribbon, 23 drive unit, 24 ribbon row, 30 display device, 31 lamp,
32 collimator lens, 33 volume hologram element, 34 cylindrical lens, 35 galvanometer mirror, 36 projection lens, 37 projection plane

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03B 33/12 G03B 33/12

Claims (12)

[Claims] A plurality of ribbons each having a plurality of minute ribbons arranged one-dimensionally on a substrate, wherein each of the ribbons in each of the ribbon rows is driven independently of each other, whereby The main body of the substrate is capable of ascending or descending, and each of the ribbon rows receives light in a different wavelength range, and spatially modulates and reflects the incident light. Spatial modulator. 2. A light source for emitting light in a predetermined wavelength range, light emitted from the light source is one-dimensionally incident for each wavelength range, and a one-dimensional space is provided at an incident position of each light. A plurality of modulation elements are provided, and a spatial modulator that spatially modulates the incident light by each spatial modulation element for each wavelength range, and multiplexes the light modulated for each wavelength range by the spatial modulator. And a projection mechanism for displaying an image by scanning and projecting the light multiplexed by the multiplexing mechanism in a predetermined direction and projecting the multiplexed light. Display device. 3. The spatial modulator includes, as the one-dimensional spatial modulation element, a plurality of ribbon rows in which a plurality of minute ribbons are one-dimensionally arranged on a substrate. 3. The image display device according to claim 2, wherein each ribbon is independently driven so as to be able to move up and down with respect to the main surface of the substrate. 4. The image display device according to claim 2, wherein the multiplexing mechanism includes a volume hologram element, a plane hologram element, a diffraction grating, or a dichroic mirror. 5. The multiplexing mechanism according to claim 1, further comprising a volume hologram element multiplexed and recorded so as to combine light incident from different directions and emit the light in a fixed direction. 5. The image display device according to 4. 6. The image display device according to claim 4, wherein the multiplexing mechanism includes a plurality of volume hologram elements for emitting light incident from different directions in respective fixed directions. 7. The light source according to claim 1, further comprising: a plurality of light sources that emit light in different wavelength ranges and cause the emitted light to be incident on spatial modulation elements of the spatial modulator. 2. The image display device according to 2. 8. A demultiplexing mechanism for demultiplexing the light emitted from the light source into light of different wavelength ranges, and causing the demultiplexed light to enter the spatial modulation elements of the spatial modulator, respectively. The image display device according to claim 2, wherein: 9. The image display device according to claim 8, wherein the demultiplexing mechanism includes a volume hologram element, a plane hologram element, a diffraction grating, or a dichroic mirror. 10. A volume hologram element which is multiplex-recorded so that light incident from a certain direction is demultiplexed for each wavelength region and emitted in different directions, as said demultiplexing mechanism. The image display device according to claim 9, wherein: 11. The image display device according to claim 9, wherein the demultiplexing mechanism includes a plurality of volume hologram elements for emitting light incident from a certain direction in different directions. 12. Each spatial modulation element of the spatial modulator,
Modulates light corresponding to different regions in an image to be displayed, and the projection mechanism projects light modulated by each spatial modulation element of the spatial modulator to a different position for each wavelength range, and projects each light. 3. The image display device according to claim 2, wherein a color-displayed image is displayed by adjusting the position and sequentially scanning.