JP2001166273A - Color-generating device and projection display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a color-generating device. SOLUTION: The color-generating device comprises at least three kinds of wavelength selective reflection elements 4r, 4b, 4g arranged in parallel with each other and reflecting three kinds of wavelength bands and a plurality of elements 1, 2, 3 for rotating the planes of polarization arranged on respective incident sides of the wavelength selective reflection element 4r, 4b, 4g.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a color generation device and a projection display device.

[0002]

2. Description of the Related Art As a color generating element used in a projection display device such as a liquid crystal projector, three LCD panels for displaying red, green and blue, three dichroic mirrors and a plurality of mirrors are used. A plate system is common. But,
The three-plate system has a large number of parts, is difficult to assemble and adjust, and is an expensive device.

Further, as a time-division type color generating element,
Japanese Patent Application Laid-Open No. 8-51633 discloses a mechanism in which three regions of red, blue, and green are provided on a disk, and white light is sequentially transmitted through these three regions to convert them into a red light beam, a blue light beam, and a green light beam. It is described in the gazette. A light beam emitted from such a color generator is emitted to a digital micromirror device (DMD) array, thereby displaying a sequential color image.

[0004] The DMD array is, for example, one in the case of XGA.
Approximately 800,000 fine mirrors are arranged in a 7 mm x 13 mm rectangle to form a single panel. Such fine mirrors are formed on a silicon substrate by changing reflection angles one by one, and turn on and off light from a light source. Then, color gradation is controlled by ON and OFF digitally to obtain a color image.

The optical system of the sequential color image device has a structure as shown in FIG. 1A, for example. In FIG. 1A, light emitted from a light source 101 is reflected by a reflector 102, and then reflected by a color generating element 103,
The light is irradiated to the DMD array 105 through the lens 104,
The light reflected by the D array 105 is projected through a projection lens 106 onto a screen (not shown).

As shown in FIG. 1B, the color generating element 103 includes a red (R), green (G), and blue (B) color filter.
103R, 103G, 103B, or a rotating disk that combines them with a dichroic mirror, DM
It is rotated in synchronization with the display of the D array 105.

[0007]

However, the time-division type color generating element 103 is mechanically driven to sequentially change the illumination light and has a large size, which hinders miniaturization of the optical system. . SUMMARY OF THE INVENTION An object of the present invention is to provide a color generation device that can be reduced in size and a projection display device having the color generation device.

[0008]

An object of the present invention is to provide at least three light sources arranged in parallel and reflecting three wavelength bands.
The problem is solved by a color generation device comprising: a plurality of types of wavelength-selective reflective elements; and a plurality of polarization plane rotation elements disposed on each light incident side of the wavelength-selective reflective elements.

In the above-described color generating apparatus, the adjacent one of the plurality of polarization plane rotation elements may be:
It may have a structure in which directions of polarization plane rotation are opposite to each other. In the above-described color generating apparatus, the plurality of polarization plane rotation elements may be arranged such that a nematic liquid crystal that is homogeneously aligned is sealed and the orientation direction of the adjacent polarization plane rotation elements is inclined by 90 °.

In the above-described color generating apparatus, the plurality of polarization rotators have a birefringence function and have a phase difference of λ /.
4 (λ; wavelength) or more. In the above-described color generation device, the plurality of polarization plane rotation elements have a function of changing a phase difference by voltage control, and a phase difference in the wavelength band of reflection by the wavelength selective reflection element is λ / 4.
There may be provided a voltage control unit for separately applying a voltage near (λ; wavelength) or a voltage whose phase difference is sufficiently small to the plurality of polarization plane rotating elements.

Next, the operation of the present invention will be described. According to the present invention, at least three types of wavelength selective reflection elements that reflect three types of wavelength bands, and a plurality of polarization plane rotation elements arranged on the respective light incident sides (closer to the light source) of the wavelength selective reflection elements Are combined to form a color generation device. In this case, the polarization state of each polarization plane rotation element is adjusted, and red, blue and green light fluxes are selected and reflected by the wavelength selection reflection element.

Therefore, a mechanical mechanism for rotating the color generation device is not required, and the size of the device can be reduced.
As such a color generation device, for example, there is a liquid crystal panel having birefringence, and a circularly polarized state having a phase difference of λ / 4 before and after light passes through the liquid crystal panel, or a state in which a phase difference is not generated. The polarization plane of light in a specific wavelength band can be made different from the polarization plane of other light.

Further, according to the projection display apparatus of the present invention, a reflective and stationary color generating element for sequentially selecting and outputting light of different colors in a wavelength band is used, and the light is interlocked with a change in the wavelength of the light. Since a structure is used in which an image display for generating a color image is used and the selected light is reflected or transmitted to the image display and transmitted to the projection lens, the size of the projection display device can be reduced.

In this case, if a polarizing beam splitter is used as an element for polarizing the optical path of light, the polarization of the optical path is facilitated, and the light can be vertically incident on and reflected from the display element, and the size of the optical system can be reduced. it can.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 2 is a sectional view showing a basic configuration of a color generation device (color generation element) according to a first embodiment of the present invention.

In FIG. 2, first to third liquid crystal panels (polarization plane rotating elements) 1, 2, and 3 are arranged in parallel in the light traveling direction in order, and the first and second liquid crystal panels of the first and second liquid crystal panels are arranged in parallel. A first dichroic mirror 4r is sandwiched between 1 and 2, a second dichroic mirror 4b is sandwiched between the second and third liquid crystal panels 2 and 3, and a third dichroic mirror 4b is further sandwiched between
A third dichroic mirror 4g is arranged on the side of the liquid crystal panel 3 opposite to the position where the second liquid crystal panel 2 is arranged.

The first to third liquid crystal panels 1, 2 and 3 respectively include liquid crystal layers 1b, 2b and 3b sandwiched between a pair of transparent electrodes 1a, 2a and 3a and a pair of transparent substrates 1c and 2 respectively.
c, 3c, and the transmitted light is λ / 4
It is manufactured so that a phase difference of about (λ; wavelength) occurs. The control signal V ₁ is connected to the pair of transparent electrodes 1 a of the first liquid crystal display panel 1, and the control signal V ₁ is connected to the pair of transparent electrodes 2 a and 3 a of the second and third liquid crystal display panels 2 and 3. The signals V ₂ and V ₃ are connected.

The first to third liquid crystal panels 1, 2, and 3 respectively transmit light without polarization when a high level voltage is applied to the transparent electrodes 1a, 2a, 3a.
When a low level voltage is applied to the transparent electrodes 1a, 2a, 3a, the polarization plane of light is rotated by 90 °. Also, the first to third liquid crystal panels 1, 2, 3
Each is configured to rotate the polarization plane of light incident from one direction in the forward direction and rotate the polarization plane of light incident from the opposite direction in the opposite direction. Further, the second liquid crystal panel 2 is configured to rotate the plane of polarization of light traveling in the same direction in a direction opposite to that of the first and third liquid crystal panels 1 and 3.

As a material of the liquid crystal layers 1b, 2b, 3b,
For example, a nematic liquid crystal having a homogeneous alignment, a ferroelectric liquid crystal, a VA liquid crystal, or a 45 ° twisted nematic liquid crystal in which the 45 ° alignment direction is changed is used. In the following description, a nematic liquid crystal having a homogeneous alignment is employed. This liquid crystal becomes circularly polarized when light is transmitted, as in a λ / 4 retardation plate, and the light is reflected by a dichroic mirror and, when transmitted again, rotates the polarization plane by 90 ° as in a λ / 2 retardation plate. Things.

The liquid crystal layers 1b, 2b, 3b
Although not particularly shown, an alignment film is interposed between the liquid crystal layers 1b, 2b, 3b and the transparent electrodes 1a, 2a, 3a. The first dichroic mirror 4r is a mirror that reflects the wavelength of red (R) and transmits colors of other wavelengths, and the second dichroic mirror 4b reflects the wavelength of blue (B). Further, the third dichroic mirror 4g is a mirror that reflects the wavelength of green (G) and transmits the colors of other wavelengths.

The first to third dichroic mirrors 4r,
Reference numerals 4b and 4g each include a dielectric multilayer film formed on a glass substrate, for example. As shown in FIG. 3, glass substrates on which such a multilayer film is formed are first to first.
The glass substrates 1c, 2c, 3c on the light reflection side that constitute the third liquid crystal panels 1, 2, 3 may be used, or as shown in FIG. Glass substrate 5
May be used. Glass substrate 1 for liquid crystal panels 1, 2, 3
Dichroic mirrors 4r, 4c, 4c, 2c, 3c
Forming b and 4g is effective in reducing the number of parts. In order to prevent the dichroic mirrors 4r, 4b, and 4g from being exposed, it is effective to use another glass substrate 5.

The surface on which the multi-layer films forming the dichroic mirrors 4r, 4b, 4g are formed may be on the liquid crystal layers 1b, 2b, 3b side of the glass substrates 1c, 2c, 3c as shown in FIG. According to this structure, the dichroic mirrors 4r, 4b, and 4g are not damaged during fabrication. In addition, the glass substrates 1c, 2c, 3c, 5 or the glass substrates 1c, 2c, 3c and the dichroic mirror 4r,
In the case of bonding 4b and 4g, a color generation device with less interfacial reflection is configured by using a transparent adhesive having a refractive index close to that of glass.

As shown in FIG. 6, a liquid crystal layer 1b, 2b, 3b is sandwiched between four glass substrates 6, and a dichroic mirror (multilayer) is provided on the reflection side surface of the liquid crystal layer 1b, 2b, 3b. When films 4r, 4b and 4g are formed,
An adhesive layer for adhering the glass substrates to each other is not required, the amount of light absorbed is reduced, and a thin device is realized. The third
The dichroic mirror 4g may be a general metal film that reflects the entire visible light region, for example, an aluminum film.

The dichroic mirror is an example of a wavelength selective reflection element, and another element may be used instead of the dichroic mirror. The arrangement of the above-described first to third dichroic mirrors 4r, 4b, 4g is not limited to the above-described order, and is desirably adjusted to the light spectrum distribution of the light source in consideration of the light loss of transmitted light. That is, in the light generation device, a dichroic mirror that reflects a color having the highest intensity among red, blue, and green of the light spectrum is disposed rearward in the light incident direction, and a dichroic mirror that reflects a color having the lowest intensity. Is preferably arranged in front of the light incident direction.

For example, if the light source is an ultra-high pressure mercury lamp,
Since the light intensity is higher in the order of green, blue, and red (G>B> R), the dichroic mirrors are arranged in the direction away from the light source in the order of red reflection, blue reflection, and green reflection as described above.
When the light source is a metal halide lamp or a halogen lamp, the light intensity is higher in the order of green, red, and blue (G>R>
B) Therefore, dichroic mirrors are arranged in the order of blue reflection, red reflection, and green reflection in the direction away from the light source.

Color Generation Method A method for generating red, blue and green light by the color generation apparatus having the above configuration will be described below. In the color generator, first to third respective transparent electrodes 1a of the liquid crystal panel 1, 2, 3, 2a, the 3a, power source V _1, V _2, V
₃ , for example, the AC pulse voltages Vr and Vb shown in FIG.
, Vg.

When the pulse voltages Vr, Vb, Vg exceed a certain fixed voltage (generally about 5 V), each liquid crystal layer 1
b, 2b, 3b become isotropic, and the function of rotating the plane of polarization disappears. Therefore, by adjusting the voltage value, it becomes possible to rotate the polarization plane of the light beam reflected by the dichroic mirror. By sequentially changing the liquid crystal layer to be applied, it becomes possible to sequentially emit light of a necessary wavelength band from the first liquid crystal panel 1.

In order to generate a λ / 4 phase difference in the liquid crystal layers 1b, 2b, 3b of the first to third liquid crystal panels 1, 2, 3, a general liquid crystal generating a λ / 2 phase difference The layer is thinner than the liquid crystal layer of the panel, and high-speed driving is possible.
A ferroelectric liquid crystal capable of realizing ultra-high-speed driving may be used. Further, a VA liquid crystal that can be vertically aligned with a nematic liquid crystal can be realized. It should be noted that if a liquid crystal and an orientation equivalent to a λ / 4 retardation plate can be realized, it can be applied to this color generating element.

The pulse voltages Vr, Vb, Vg are, for example, 60 Hz. Further, it is desirable to apply an alternating current in the same manner as in general liquid crystal driving. Then, 0-1
The third cycle, the 1/3 to 2/3 cycle, and the 2/3 to 3/3 cycle will be described. (i) 0 to 1/3 period First, as shown in FIG. 7, in the first 1/3 period of the pulse voltages Vr, Vb, Vg, light reflection and polarization as shown in FIG. .

That is, as shown in FIG. 8A, a pair of transparent electrodes 1 of each of the first and second liquid crystal panels 1 and 2 is provided.
The voltage application to the a and 2a is turned off, while the voltage application to the space 3a between the pair of electrodes of the third liquid crystal panel 3 is turned on. In this period, the white light is linearly polarized by a polarizing element described later and is irradiated toward one surface of the first liquid crystal panel 1.

The red luminous flux (R) contained in the white light is shown in FIG.
As shown in (a), the light is circularly polarized by the first liquid crystal panel 1 in the normal rotation, transmitted through a phase difference of λ / 4, and radiated to the first dichroic mirror 4r. Then, the first dichroic mirror 4r reflects and inverts the circularly polarized light of the red light beam. The reflected red light beam passes through the first liquid crystal panel 1 again, is reversely rotated, and is linearly polarized.
As a result, the red light flux returned from one surface of the first liquid crystal panel 2 is rotated by 90 ° with respect to the incident red light flux, and thereby becomes, for example, light having a polarization plane perpendicular to the paper surface.
Accordingly, a red light beam can be selectively extracted by a polarizing element that transmits light having a polarization plane perpendicular to the paper surface.

The blue light flux (B) contained in the white light
As shown in FIG. 8 (a), the light passes through the first liquid crystal panel 1, is circularly polarized by the forward rotation, is transmitted, and is transmitted through the first dichroic mirror 4r as it is. further,
The blue luminous flux transmitted through the first dichroic mirror 4r is transmitted through the second liquid crystal panel 2, reversely rotated and returned to the original linearly polarized light, and irradiated as it is on the second dichroic mirror 4b. . The blue light flux reflected by the second dichroic mirror 4b is transmitted through the second liquid crystal panel 2, the first dichroic mirror 4r, and the first liquid crystal panel 1 in this order. Since the second liquid crystal panel 2 and the first liquid crystal panel 1 are circularly and linearly polarized by the opposite rotation, blue light emitted from one surface of the first liquid crystal panel 1 is incident from one surface thereof. It becomes a linearly polarized light of the same angle as that of the above.

Further, a green luminous flux (G) contained in white light
As shown in FIG. 8 (a), the light passes through the first and second liquid crystal panels 1 and 2 and the first dichroic mirror 4r in the same state as the blue light flux, and the second dichroic mirror 4b
Is irradiated. The green light flux transmitted through the second dichroic mirror 4b is transmitted through the third liquid crystal panel 3 without being polarized, and is reflected by the third dichroic mirror 4g. The reflected green light beam passes through the third liquid crystal panel 3 and the second dichroic mirror 4b as it is, and then, like the blue light beam, the second liquid crystal panel 2 and the first dichroic mirror 4r. , Through the first liquid crystal panel 1 in order. The green luminous flux emitted from one surface of the first liquid crystal panel 1 is circularly and linearly polarized by the second liquid crystal panel 2 and the first liquid crystal panel 1 by rotations opposite to each other. It has the same polarization plane as when entering the panel 1.

As described above, the red light beam emitted from the first liquid crystal panel 1 has a polarization plane of 90 degrees with the blue and green light beams.
゜ Because the light is different, the white light can be selected by a polarizing element different from the polarized light. The light other than the red, blue, and green light fluxes is transmitted to the first to third liquid crystal panels and the first to third dichroic mirrors 4e, 4b, 4
8A, the light does not return to the first surface of the first liquid crystal panel 1 as shown in FIG.

(Ii) 1/3 to 2/3 period First, 1/3 of the pulse voltages Vr, Vb and Vg shown in FIG.
In the period of 3 to 2/3, light reflection and polarization are performed as shown in FIG. That is, in FIG. 8B, a pair of transparent electrodes 2 of each of the second and third liquid crystal panels 2 and 3 is shown.
The voltage application to the pair of transparent electrodes 1a of the first liquid crystal panel 1 is turned on while the voltage application to the a and 3a is turned off. In this case, the white light is linearly polarized by the first linear polarizing plate and is irradiated toward one surface of the first liquid crystal panel 1. The linearly polarized light propagates, for example, on a plane of polarization parallel to the paper surface.

The red luminous flux (R) contained in the white light is shown in FIG.
As shown in (b), the first dichroic mirror 4r passes through the first liquid crystal panel 1 without rotating the polarization plane.
The first dichroic mirror 4r reflects the red light beam as it is, and the reflected red light beam passes through the first liquid crystal panel 1 again without rotating its polarization plane. As a result, the red light beam emitted from one surface of the first liquid crystal panel 1 has the same polarization plane as the red light beam incident on the one surface. Therefore, the red light beam is prevented from traveling by the polarizing element that transmits only linearly polarized light perpendicular to the paper surface.

The blue luminous flux (B) contained in white is
As shown in FIG. 8B, the light passes through the first liquid crystal panel 1, the first dichroic mirror 4r, and the second liquid crystal panel 2 and is reflected by the second dichroic mirror 4b. The blue luminous flux passes through the second liquid crystal panel 2 to be circularly polarized by reverse rotation, and is further reflected and inverted by the second dichroic mirror 4b. Then, the reflected blue light beam passes through the second liquid crystal panel 2 and is circularly polarized by positive rotation, thereby becoming linearly polarized light rotated by 90 ° with respect to the state of being incident on the first liquid crystal panel 1. And the first dichroic mirror 4 as it is
r, the first liquid crystal panel 1 transmitting through the first liquid crystal panel 1
Is emitted to one surface side of.

Further, a green luminous flux (G) contained in white
Are the first liquid crystal panel 1 and the first liquid crystal panel 1 as shown in FIG.
Through the dichroic mirror 4r, the second liquid crystal panel 2, the second dichroic mirror 4b, and the third liquid crystal panel 3, and is reflected by the third dichroic mirror 4g. In this case, the green luminous flux is circularly polarized by the second liquid crystal panel 2 in the reverse rotation, but is returned to the original linearly polarized light by the third liquid crystal panel 3 by the normal rotation, so that the third dichroic mirror 4 g It is reflected in the state of linearly polarized light. Further, the green luminous flux reflected by the third dichroic mirror 4g proceeds toward the first liquid crystal panel 1, but when passing through the second and third liquid crystal panels 2 and 3, the green luminous flux reverses to the normal rotation. The light is turned into a circularly polarized light and a linearly polarized light by rotation, and consequently returns to the original state and exits from one surface side of the first liquid crystal panel 1.

As described above, the blue light beam emitted from the first liquid crystal panel 1 has a linear polarization different from the red and green light beams by 90 °, and can be selectively extracted.
The light other than the red, blue, and green light fluxes is applied to the first to third liquid crystal panels 1, 2, 3 and the first to third dichroic mirrors 4.
Since the light passes through r, 4b, and 4g, it does not return to the one surface side of the first liquid crystal panel 1 as shown in FIG.

(Iii) 2/3 to 3/3 period First, as shown in FIG. 7, in the 2/3 to 3/3 period of the pulse voltages Vr, Vb and Vg, as shown in FIG. Light reflection and polarization are performed. That is, as shown in FIG. 8C, while the voltage application to the pair of transparent electrodes 1a and 2a of the first and second liquid crystal panels 1 and 2 is turned on, the third liquid crystal panel 3 is turned on. The voltage application to the pair of transparent electrodes 3a is turned off. In this case, the white light is linearly polarized by the first linear polarizing plate and is irradiated toward one surface of the first liquid crystal panel 1. The linear polarization plane is, for example, parallel to the paper.

The red luminous flux (R) included in the white light is shown in FIG.
As shown in (c), the light is irradiated by the first dichroic mirror 4r after passing through the first liquid crystal panel 1 without rotating its polarization plane. The first dichroic mirror reflects the red light beam as it is, and the reflected red light beam passes through the first liquid crystal panel 1 again without rotating its polarization plane. As a result, the red light beam emitted from one surface of the first liquid crystal panel 1 propagates on the same polarization plane as the incident red light beam.

The blue luminous flux (B) contained in the white light
As shown in FIG. 8C, the first liquid crystal panel 1 and the first dichroic mirror 4 are rotated without rotating their polarization planes.
r, the blue light flux transmitted through the second liquid crystal panel 2 and reflected by the second dichroic mirror 4b travels in the opposite direction and is emitted from one surface of the first liquid crystal panel 1.

Further, a green luminous flux (G) contained in white light
The first liquid crystal panel 1 and the first liquid crystal panel 1, as shown in FIG.
Through the dichroic mirror 4r, the second liquid crystal panel 2, the second dichroic mirror 4b, and the third liquid crystal panel 3, and is reflected by the third dichroic mirror 4g. In this case, the green light beam is circularly polarized by the third liquid crystal panel 3 in the forward rotation, but is reflected and inverted by the third dichroic mirror 4g, and then reversely transmitted through the third dichroic mirror 4g. The light is linearly polarized by rotation and becomes linearly polarized light. The polarization plane of this blue light beam is
The green light flux incident on the first liquid crystal panel 1 is rotated by 90 ° with respect to the polarization plane. Then, the green light flux in the linearly polarized state is emitted from one surface side of the first liquid crystal panel 1 without further rotating its polarization plane.

As described above, the green light beam emitted from the first liquid crystal panel 1 has a linear polarization different from the red and blue light beams by 90 °, and can be selectively extracted. Note that light other than the red, blue, and green light fluxes is transmitted through the first to third liquid crystal panels 1, 2, 3 and the first to third dichroic mirrors 4r, 4b, 4g. Does not return to the one surface side of the first liquid crystal panel 1 as shown in FIG.

According to the above-described color generator, red, blue, and green light are periodically emitted as shown in FIG. 9 without requiring a large-scale structure such as a rotary mechanism such as a vaporizer. It becomes possible. Note that the linear polarization plane of the light incident on the first liquid crystal panel 1 is not limited to being parallel to the paper as described above. Arrangement of Liquid Crystal Panels The above-described first to third liquid crystal panels 1, 2, 3 are arranged as follows.

The second liquid crystal panel 2 disposed between the first and third liquid crystal panels 1 and 3 has a function opposite to the function of rotating the polarization plane by the first and third liquid crystal panels 1 and 3. Are arranged to produce That is, when the first and third liquid crystal panels 1 and 3 change linearly polarized light into circularly polarized light, the second liquid crystal panel 2 is arranged so as to change circularly polarized light into linearly polarized light. When the third liquid crystal panels 1 and 3 change circularly polarized light into linearly polarized light, the second liquid crystal panel 2 is arranged to change linearly polarized light into circularly polarized light.

For example, when the liquid crystal panels 1, 2, and 3 have a nematic liquid crystal homogeneous alignment, as shown in FIG. 10, the liquid crystal layer 1b of the first liquid crystal panel 1 has an angle θ (for example, 45 °) The liquid crystal layer 2b of the second liquid crystal panel 2 is set to θ + 90 ° or 90 ° −θ (for example, 135 °), and the liquid crystal layer 3b of the third liquid crystal panel 3 is set to θ (for example, 45 °). The orientation is inclined. The alignment direction is determined by adjusting the rubbing direction of the alignment film sandwiching the liquid crystal layer.

By the way, from the general relationship between the wavelength of liquid crystal and the dispersion of the refractive index, the wavelength and the phase difference of the liquid crystal layer have the relationship shown in FIG. For example, at the wavelength of green (G), λ / 4 (π /
When a liquid crystal layer having a phase difference of 2) is prepared, the phase difference is smaller than λ / 4 at the wavelength of red (R) in the liquid crystal layer, and is smaller than λ / 4 at the wavelength of blue (B). Is also getting bigger. According to such a liquid crystal layer, the amount of polarization rotation of the light transmitted through the liquid crystal layer differs between the wavelengths, and the variation in the amount of polarization at each wavelength transmitted through the plurality of liquid crystal layers further increases.

For example, the first to third liquid crystal panels 1, 2, 2
If the alignment directions of the liquid crystal panels 3 are all the same, or if the amounts of polarization of the liquid crystal panels 1, 2, and 3 are adjusted to one wavelength, the luminous flux reflected by the dichroic mirror differs in the amount of rotation of the polarized light for each wavelength. It is difficult to selectively separate and extract only light having a wavelength of. Therefore, as shown in FIG. 10 and FIG. 12, when the alignment directions are alternated, when the linearly polarized light is circularly polarized by the two liquid crystal panels and then returned to the linearly polarized light, the dispersion of the phase difference of each wavelength is reduced. All are canceled. As a result, an ideal amount of polarization rotation can be added for each wavelength. In other words, it is possible to completely return the light beam obtained by converting the linearly polarized light into the circularly polarized light to the linearly polarized light with respect to all the wavelengths later, and it becomes easy to separate and extract the light of the specific wavelength by the polarizing element.

Applied Voltage Value to Voltage of Liquid Crystal Panel It is desirable to use the same first to third liquid crystal panels in order to simplify the manufacturing process. That is,
It is advantageous for cost reduction that all liquid crystal materials and liquid crystal gaps are the same. Therefore, when the same nematic liquid crystal is used in all of the first to third liquid crystal panels,
Λ / 4 for all red, blue, and green luminous flux
A method for generating a phase difference of (π / 2) will be described below.

First, the red light beam having the longest wavelength is λ / 4.
Three liquid crystal panels that produce only a phase difference are produced. Then, reference voltages corresponding to red, blue, and green colors are applied to a pair of electrodes sandwiching the liquid crystal layer in the first to third liquid crystal panels, respectively, and circularly polarized light with a phase difference of λ / 4. That is, in a liquid crystal panel of the same structure that encapsulates nematic liquid crystal,
The relationship between the applied voltage value and the phase difference for each of the red, blue, and green light beams is as shown in FIG. 11, and the phase difference between each of the red, blue, and green light beams is changed by λ /
4 is possible. The voltage for sufficiently eliminating the phase difference is Vm irrespective of the color difference.

Here, a reference voltage which causes a phase difference of λ / 4 in the red light beam is V _r0 , a reference voltage which causes a phase difference of λ / 4 in the blue light beam is V _b0, and a reference voltage which causes a phase difference of green light beam is V _b0. The reference voltage that causes a phase difference of λ / 4 is V _g0 . Therefore, when the color generating device shown in FIG. 2 is configured by using three liquid crystal panels having the same structure, the voltage shown in FIG.
When changing as shown in FIG. 14 and selecting any one of red, blue and green light fluxes, the value of the voltage applied to the electrodes of the first to third liquid crystal panels is a combination as shown in FIG. Thus, polarized light similar to that shown in FIGS. 8A to 8C can be obtained.

When the temperature of the liquid crystal panel rises due to light irradiation, the phase difference due to the liquid crystal layer is reduced. Therefore, the thickness of the liquid crystal layer of the liquid crystal panel, that is, the gap between the transparent substrates 1c (2c, 3c) is made slightly thicker to secure a sufficient phase difference, and the reference voltage applied to each liquid crystal panel is optimized to adjust the phase. I do. When the temperature change is large, an optimum voltage adjustment can be performed in accordance with the temperature change by improving the circuit system for feeding back monitor unit data such as a sensor.

Further, the liquid crystal layers 1b and 23 of the liquid crystal panel
In the case where the response speeds of b and 3b are slow, as shown in FIG. 16, by slightly advancing the timing of voltage application, the luminous flux of each color reflected by the color generation device and whose polarization plane is rotated by 90 ° is plotted. As shown in FIG. 17, the display can be synchronized with the display of a display element such as a DMD array. The transparent electrodes 1a and 1a of the first to third liquid crystal panels 1, 2 and 3 shown in FIG.
When the voltage shown in FIG. 7 is applied to 2a and 3a, for example, as shown in FIG. 18, a prism-shaped polarizing beam splitter (PBS) 7 is used as a polarizer on one surface side of the first liquid crystal panel 1. Deploy. Thus, when a white light beam enters the front of the polarization beam splitter 7, the red, blue, and green light beams generated by the light generation device 10 can be sequentially extracted to the side of the polarization beam splitter 7.

When a projection display device is constructed using such a polarization beam splitter 7 and a color generation device 10, a configuration as shown in FIG. 19 is employed. In FIG. 19, the polarizing beam splitter 7 is, for example, one in which the bottom surfaces of two right-angle prisms are adhered to each other. A polarizing film 7a that reflects other light is formed.

A white light source 11 is disposed on the opposite side of the polarization beam splitter 7 from the color generator 10. A reflector 12 is arranged around the light source 11 for white light, and the light emitted from the light source 11 is converted into parallel light by the reflector 12 and emitted to the color generator 10 through the polarization beam splitter 7. It has become. In the polarization beam splitter 7, a polarizer 13 that transmits a linearly polarized light beam is disposed in the traveling direction of light from the light source 11 reflected by the polarization film 7a. The polarizer 13 has a structure in which, for example, only a light beam having a polarization plane parallel to the paper surface is transmitted, and other light is absorbed.
A projection lens 14 is disposed in front of the light traveling direction of the polarizer 13.

Further, a display element 15 such as a DMD array is arranged on the side of the polarization beam splitter 7 opposite to the polarization element 13. The display element 15 has a structure in which the incident light beam is rotated by 90 ° and reflected. In the polarizing beam splitter 7, the surface facing the light source 11 is the first surface, the surface facing the polarizer 13 is the second surface, and the surface facing the color generator 10 is the first surface. The surface facing the display element 15 is the fourth surface.

Such a projection display device obtains a color display as follows. First, the light emitted from the light source 11 for white light passes through the first surface of the polarizing beam splitter 7 and irradiates the polarizing film 7a. Of the white light applied to the polarizing film 7a, light parallel to the paper surface passes through the polarizing film 7a and is applied to the color generator 10, while the other light is reflected and absorbed by the polarizer 13.

The white light applied to the color generator 10 is applied to the liquid crystal panels 1, 2, 3 and the dichroic mirror 4.
The red, blue and green light fluxes are selected and reflected by r, 4b and 4g and returned to the polarizing film 7a. Two light beams of red, blue, and green reflected by the color generation device 10 have, for example, a polarization plane parallel to the paper surface, and the other light beam is polarized perpendicular to the paper surface.

Of the red, blue, and green luminous fluxes generated by the color generator 10, the luminous flux having a polarization plane perpendicular to the paper is reflected by the polarizing film 7a and radiated to the display device 15, and is further parallel to the paper. The light on the polarization plane passes through the polarizing film 7a and returns to the light source 11. The light beam applied to the display element 15 is
The light is reflected by being rotated by 90 ° by the
a, the polarizer 13, the projection lens 14 and the screen S
Go straight to.

The wavelength band (color) for reflecting the polarizing film 7a is sequentially switched in synchronization with the change of the display element that is periodically displayed sequentially, and the luminous flux in the required wavelength band (color) is sequentially changed.
The display element 15 is irradiated. Thereby, a color image is displayed on a screen or the like. Since the prism constituting the polarizing beam splitter 7 has a large volume and is expensive,
When the prism is not desired to be used, as shown in FIG. 20, a polarizer 16 having a transmission axis in only one direction parallel to the front surface of the above-described color generator 10 is disposed in front of the polarizer 16, and FIG. , Vr, Vb, Vg as shown in FIG.
To the transparent electrodes 1a, 1a,
By applying the light to 2a and 3a, the light of the color to be selected is emitted from the first liquid crystal panel without being polarized, and the light of the color not to be selected is rotated by 90 ° and absorbed by the polarizer 16. .

According to this, as shown in FIG. 20, a polarizer for linearly polarizing white light when it is incident can be used also as a polarizer for color selection. Simple and inexpensive. In addition,
The color generation device may or may not include a polarizer as a concept. (Second Embodiment) In the first embodiment, three colors are extracted in a time-division manner by the color generation device.
A light beam of 波長 is used, and light of other wavelengths is lost.

However, a display device such as a projector may display in black and white (monaural). Therefore, a method of effectively using a light beam in displaying black and white will be described below. In the projection display device provided with the polarization beam splitter 7 shown in FIG. 19, if all the RGB light beams become linearly polarized light rotated by 90 °, all the RGB light beams will be irradiated on the projection lens 14, Loss is reduced.

Therefore, as shown in FIG. 23, the voltage applied to the transparent electrode 1a of the first liquid crystal panel 1 is set to V _g0, and the voltage applied to the transparent electrodes 2a and 3a of the second and third liquid crystal panels 2 and 3 is set. Assuming that the applied voltage is Vm, all the light can be rotated by 90 ° and emitted from the polarization beam splitter 7. In this case, the voltage V _r0 is applied to the transparent electrode 1a of the first liquid crystal panel 1.
Instead of applying the voltage V _g0 , the intermediate voltage V _g0
This is to reduce the difference in the amount of rotation due to the difference in RGB wavelength.

When the polarizer 16 for linearly polarized light is arranged in front of the first liquid crystal panel 1 as shown in FIG. 20, the first to third liquid crystal panels are arranged as shown in FIG. When the same voltage Vm is applied to all of the transparent electrodes 1a, 2a, 3a of 1, 2, and 3, all the RGB light beams are
, And incident on the color generation device 10, the first to third dichroic mirrors 4 r, 4 b, 4 g
And is emitted from the polarizer 16. In this case, there is no polarization due to the liquid crystal panels 1, 2, and 3,
Light loss is reduced.

The color display described in the first embodiment and the monochrome display in the present embodiment can be in the middle. Adjustment is possible by a combination of voltage application. (Third Embodiment) In order to use the color generation device described in the first and second embodiments in a color display device such as a color projector, a color change at 180 Hz must be realized. To the human eye, the image looks natural up to about 60 Hz due to the afterimage effect. Therefore, in order to realize a color between 60 Hz, three times 180 Hz (5.5 m) is required.
s) A high-speed color switching speed is required. It is known that the response speed of liquid crystal is inversely proportional to the square of the liquid crystal gap.

A commonly used nematic liquid crystal has a response speed of about 20 ms with a gap of 5 μm between the electrodes 1 a (2 a, 3 a), and 5 μm / √ (20 ms / 5.5 ms) in order to realize 180 Hz. ) ≒ 2.
This can be realized with a gap between electrodes of 6 μm or less. Therefore, to change the color at a response speed of 180 Hz,
The gap between the electrodes, that is, the thickness of the liquid crystal layer needs to be 2.6 μm or less. (Fourth Embodiment) In this embodiment, a method for improving optical characteristics will be described.

If the rotation of the polarized light is not appropriate and the linearly polarized light is in an elliptically polarized state, noise is included or a necessary light beam is cut off at the time of color separation and extraction by the polarizer. Therefore, in the method of the above-described embodiment, it is desired to completely eliminate the phase difference caused by the liquid crystal layer when applying a voltage (Vm) for reducing the phase difference caused by the liquid crystal layer to zero. However, as shown in FIG. 25, there are liquid crystal molecules that are firmly aligned at the interface between the liquid crystal layer 1b and the alignment film 8, and it is difficult to completely eliminate the phase difference by applying a certain amount of voltage. FIG. 13 also shows the characteristics.

[0069] By increasing the applied voltage V _m, the phase difference due to the liquid crystal layer is reduced, but not practical to burden the liquid crystal driving circuit. Therefore, a method that can be improved is shown in FIG. FIG. 26 (a) shows the electrode 1 of the liquid crystal panel 1.
This shows a state in which even if a high-level voltage _Vm is applied to a, the linearly polarized light is not transmitted at a phase difference of zero, but becomes elliptically polarized light due to the remaining phase difference.

Therefore, as shown in FIG. 26 (b), a phase difference film 9 for giving a reverse rotation to the remaining phase difference with a small phase difference is arranged on the liquid crystal panel 1 (2, 3), and the remaining phase difference is reduced. Cancel. The retardation film 9 can be produced by stretching a polymer. The direction of the arrow on the retardation film 9 in FIG. 26B indicates the stretching direction or the stretching perpendicular direction. The arrangement angle of the arrow has an optimum angle depending on the phase difference amount.

When the retardation of the retardation film 9 is large, the optimum arrangement angle is obtained by moving the arrow closer to parallel or perpendicular to the direction of the incident polarized light. Conversely,
If the phase difference is small, the residual phase difference amount can be optimally canceled by arranging the arrow at an angle of about 45 ° with respect to the incident polarized light. What is important in the arrangement of the retardation film 9 is an arrangement in which the direction of rotation of the linearly polarized light due to the residual retardation is reversed and canceled. Although it is possible to produce linearly polarized light by positive rotation, the amount of rotation of large polarized light differs depending on the wavelength. For example, the liquid crystal panel 1 shown in FIG.
Assuming that the direction of the arrow in the rubbing direction of the alignment film of (2, 3) is the high refractive index direction and the direction of the arrow of the retardation film 9 in FIG. This can be realized by arranging the high refractive index directions in the left and right directions with respect to the direction. The phase difference film 9 for correction may be a thin slice of a crystal plate having a birefringence. It is also conceivable to arrange a correction liquid crystal panel, but this is not realistic because absorption loss is large and cost is high.

FIG. 27 is a schematic diagram in which the first to third liquid crystal panels 1, 2, 3 are all provided with the retardation films 9a to 9c for correction. The left side of FIG. 27 is the incident surface. Note that the residual phase difference of the second or third liquid crystal panels 2 and 3 cancels the residual phase difference of the first or second liquid crystal panels 1 and 2 and may be omitted in this case.

In the driving method shown in the above embodiment,
When the second liquid crystal panel 2 has a residual phase difference, the first liquid crystal panel 1 also has a residual phase difference and is canceled, so that the correction phase difference film 9 can be omitted. Since the third liquid crystal panel 3 can perform correction by finely adjusting the voltage applied to the first and second liquid crystal panels 1 and 2, the phase difference film for correction may be omitted. But,
Since the first liquid crystal panel 1 has no other liquid crystal panel on the light incident side, it is preferable that there is no correction means, and that a retardation film is disposed at least on the light incident side of the liquid crystal panel 1. (Fifth Embodiment) In the first embodiment, as shown in FIG. 19, a display device 15 and a polarizer 13 are arranged with a polarizing beam splitter 7 interposed therebetween. In such a configuration, since the light beam that has passed through the polarization beam splitter 7 three times is applied to the projection lens 14, it is desired to reduce light loss due to the polarization beam splitter 7. In this case, FIG.
It is preferable to adopt a configuration as shown in FIG.

In FIG. 28, the bottom surfaces of two right-angle prisms constituting the polarizing beam splitter 7 used in the first embodiment are bonded to each other, and a boundary (bonding surface) 7b between the bottom surfaces is a polarized light parallel to the paper surface. The polarizing surface 7b transmits the light of the surface and reflects the other light. The light source 11 is arranged to face the color generation device 10 via the polarization beam splitter 7. Color generation device 1
A display device 15, a polarizer 13, and a projection lens 14 are sequentially arranged in the traveling direction of the light emitted from 0 and reflected on the polarization plane 7b.

The color generator 10 has the same structure as that of the first embodiment. Further, as the display device 15, a DMD
No array is applied, and a transmissive type such as a liquid crystal display device is used. According to such an arrangement, the white light emitted from the light source 11 is transmitted through the polarization beam splitter 7 and is polarized into a light beam having a polarization plane parallel to the sheet of paper, and is emitted to the color generator 10. Then, as described in the first embodiment, the color generation device 10 reflects the red, blue, and green light fluxes of the white light and returns the light flux to the polarization beam splitter 7. The red, blue, and green lights reflected from the color generator 10 are linearly polarized in the plane perpendicular to the paper in order, so that the polarization plane 7b of the polarization beam splitter 7 is Is reflected by 90 °, and is transmitted through the display device 15, the polarizing element 13, and the projection lens 14.

Therefore, the light emitted from the light source 11 passes through the polarization beam splitter 7 twice and reaches the projection lens 14, so that the light loss is smaller than in the first embodiment. (Sixth Embodiment) Regarding the characteristics of the polarizing beam splitter 7 in the first embodiment, it is most preferable that the light beam is parallel light.

When a diverging or converging light beam enters the polarizing beam splitter 7, the angle of incidence is not uniform, so that the polarization splitting characteristics of the polarizing beam splitter 7 deteriorate. Therefore, the reflector 1 arranged around the light source 11
2 is assumed to convert light from the light source 11 into parallel light. However, the display element 15 may be smaller than the light source 11 and the reflector 12 in some cases. for that reason,
When a parallel light beam is used, the display device 15 cannot be efficiently irradiated with the light beam.

Therefore, by using convergent light which is opposite to the direction in which the characteristics of the polarization beam splitter 7 is good, it is possible to efficiently irradiate the display device with a light beam. As for the characteristics of the polarization beam splitter 7, if the incident angle changes by about ± 10 °, about 90% of the polarization characteristics can be secured. If the change in the incident angle is within ± 10 ° even with convergent light, there is no problem in the characteristics, and the light use efficiency can be increased.

FIG. 29 shows the traveling state of light when such convergent light is emitted from the reflector 12. In FIG. 29, if the converging point of the convergent light by the reflector 12 is set near the display element 15 through the polarizing beam splitter 7 or the like, the display device 15 smaller than the color generation device 10 can be supported. In the case of using such convergent light, as shown in FIG. 30, by providing a stop (aperture) 17 near the projection lens 14, it is possible to suppress noise light from being incident on the projection lens 14. That is, when a focus is set in or near the stop 17, unnecessary light such as a light beam that is multiple-reflected in the polarization beam splitter 7 is suppressed from entering the projection lens 14. This makes it possible to improve the contrast of the image and obtain a high-quality image.

By the way, such unnecessary light (noise light) is, for example, a light flux indicated by a broken line in FIG.
That is, the polarization splitting characteristic of the polarizing beam splitter 7 is
Not 100% perfect. A light beam incident on the polarization beam splitter 7 from the light source 11, for example, a light beam having a polarization plane perpendicular to the plane of the paper is reflected by the polarization plane 7b of the polarization beam splitter 7 and is irradiated on the polarizer 13 by about several%. Absorbed. However, a few percent of the reflected light flux passes through the polarizing element 13.

Therefore, as shown in FIG. 31, the polarizing beam splitter 7 is disposed with a slight rotation from the center. According to this, the direction of the unnecessary light reflected by the polarization beam splitter 7 and the display light flux reflected by the display element 15 change. Projection lens 14 for projector
Generally, the angle of the light beam that can be captured is several degrees. Unless you use an unrealistic large-diameter projection lens,
If the incident angle of light is more than ± 10 °, the light cannot be projected. Therefore, when the incident angle is ± 10 ° or more, the take-in angle can be further reduced by using a projection lens having a small aperture size and a stop of the projection lens.

As shown in the first embodiment, the smallest optical system is one in which the axis of the light beam is perpendicularly incident on the display element 15. If the amount of unnecessary light is small, such a configuration may be adopted. preferable. However, when the unnecessary light incident on the polarizer 13 is reduced, as shown in FIG. 31, the polarization beam splitter 7 is inclined so that the incident angle on the display element 15 is within 10 °, that is, several degrees. Is preferred.

When the angle of incidence on the display element is within ± 10 °, the polarization plane (reflection plane) 7b inside the polarization beam splitter 7 is placed on the entrance plane of the color generator 10 as shown in FIG. Display element 1
5 and the display element 15 and the polarizer 1
The optical axes of 3 and the projection lens 14 may be inclined by several degrees.

When such a structure is adopted, the light beam from the light source 11 is in a direction perpendicular to the seven incidence planes of the polarizing beam splitter, so that a polarizing beam splitter smaller than that of FIG. 31 can be used. It becomes a small optical system. (Seventh Embodiment) In the optical system of the above-described embodiment, since a polarization beam splitter using a right-angle prism is used, polarization separation characteristics are good, and high image quality and high luminance can be realized. However, it is expensive.

Therefore, as shown in FIG. 33, a flat polarizing beam splitter 18 can be used instead of a right-angle prism. As the polarization beam splitter 18 having a plate shape, for example, a polarization beam splitter having a multilayer structure formed on a glass substrate or a film-shaped polarization separation element is used. As a polarization separation element, for example, a trade name D manufactured by 3M Company
-There is BEF.

In FIG. 33, the polarizing beam splitter 18 is rotated in a state where one surface of the polarizing beam splitter 18 is inclined by 45 ° with respect to the traveling direction of the light beam emitted from the reflector 12, and It is arranged at the position of the polarization plane 17a of the splitter. Since the flat polarizing beam splitter 18 is inexpensive, the cost of the entire optical system can be reduced. (Eighth Embodiment) A conventional liquid crystal projector has two polarizers or one reciprocating transmission using reflection. Since the polarizer absorbs about 10% of the luminous flux of the required polarization plane, the smaller the number of the sheets, the better the transmittance,
High brightness can be achieved. However, when a light source with a high output is used, all unnecessary light fluxes are absorbed by one polarizer, so that its durability becomes a problem.

In order to increase the durability, for example, as shown in FIG. 34, a polarization generation element 19 is interposed between the polarization beam splitter 7 and the light source 11, and the polarization generation element 19 causes the polarization generation element 19 to be parallel to the paper. Light on the polarization plane is selectively irradiated on the polarization beam splitter 7. As the polarization generation element 15, a polarizer, a film-like polarization separation element, or the like is used.

According to this, since the polarization generating element 19 absorbs and reflects the light beam of the unnecessary polarization plane, the projection lens 1
Only the light beam reflected from the display element 15 enters the polarization element 13 on the fourth side. Therefore, the durability of the polarizing element 15 is improved. In each of the embodiments described above,
The plane of polarization horizontal to the plane of the paper may be the plane of perpendicular polarization, and the plane of polarization perpendicular to the plane may be the plane of plane. << Appendix >> (1) At least three types of wavelength-selective reflective elements that are arranged in parallel and reflect three types of wavelength bands, and a plurality of polarization plane rotations that are disposed on respective light incident sides of the wavelength-selective reflective elements A color generation device, comprising: an element; (2) The color generation device according to (1), wherein the adjacent one of the plurality of polarization plane rotation elements has a structure in which the polarization plane rotation action is in the opposite direction. apparatus. (3) The plurality of polarization plane rotation elements are filled with homogeneously aligned nematic liquid crystal, and are arranged so that the orientation direction of the adjacent polarization plane rotation elements is inclined by 90 ° (1) or (2). The color generator according to 2). (4) The color according to (1) or (2), wherein the plurality of polarization rotators have a function of birefringence and have a phase difference of λ / 4 (λ; wavelength) or more. Generator. (5) The plurality of polarization plane rotation elements have a function of changing a phase difference by voltage control, and a phase difference in the wavelength band of reflection by the wavelength selective reflection element is in the vicinity of λ / 4 (λ; wavelength). The color generation device according to (1), further comprising: a voltage control unit that separately applies one of the following voltages and a voltage having a sufficiently small phase difference to the plurality of polarization plane rotation elements. (6) The color generator according to (5), wherein the polarization plane rotation element is a liquid crystal panel, and a phase difference switching speed by the voltage controller is 180 Hz or more. (7) The color generating device according to (3) or (7), wherein the polarization plane rotation element is filled with nematic liquid crystal and a gap of the liquid crystal is 2.6 μm or less. (8) The color generating apparatus according to (1), wherein the plurality of polarization plane rotating elements have a function of making a black-and-white display or a function close to a black-and-white display. (9) The color generation according to any one of (1) to (8), wherein any one of a retardation film and a birefringent crystal plate is arranged at a light incidence or emission portion of the polarization plane rotation element. apparatus. (10) The retardation film or the birefringent crystal plate has a polarization plane rotation action in a direction opposite to a polarization plane rotation action by the polarization plane rotation element.
The color generation device according to 1. (11) The color generator according to (1), wherein one of the three dichroic mirrors is a metal film reflector. (12) The plurality of polarization plane rotation elements are composed of liquid crystal sandwiched between a pair of transparent plates, and the dichroic mirror has a structure in which a reflection film is formed on a transparent substrate, and the polarization plane rotation element and the dichroic The color generator according to (1), wherein the mirror is bonded via an adhesive layer therebetween. (13) The plurality of polarization plane rotation elements are formed of a liquid crystal layer sandwiched between a pair of transparent plates, and the dichroic mirror is formed on one surface of each of the plurality of polarization plane rotation elements. The color generating device according to (1), wherein the color generating device is formed of a reflective film, and the polarization plane rotating elements are integrated with the dichroic mirror with an adhesive layer interposed therebetween. (14) The plurality of polarization plane rotation elements include a liquid crystal layer sandwiched between a pair of transparent plates, and the dichroic mirror is sandwiched between the liquid crystal layer of the polarization plane rotation element and one of the transparent plates. Wherein the polarizing plane rotation elements are bonded to each other via an adhesive layer (1).
The color generation device according to 1. (15) The plurality of polarization plane rotators are integrally formed with a liquid crystal layer interposed in each gap between a plurality of transparent substrates, and the dichroic mirror is formed between the liquid crystal layer and the transparent plate. The color generator according to (1), which is characterized in that: (16) a reflection type color generating element that sequentially generates light in a plurality of wavelength bands by reflecting light from the light irradiation unit, and the light in the plurality of wavelength bands irradiated from the color generating element is sequentially irradiated. A projection display device, comprising: an image display for generating a color image in association with a change in light in the plurality of wavelength bands; and a projection lens for enlarging the light reflected or transmitted by the image display. (17) The color generating element has a function of individually modulating the polarization plane of the light in the plurality of wavelength bands, and modulates the polarization plane of the light output from the color generation element to a specific wavelength. The projection display device according to (16), further including a polarization beam splitter that irradiates the image display body with light in a band. (18) The axis according to (16), wherein the axis of the light incident on the image display is set at an angle of 10 ° or less from a vertical direction with respect to a display surface of the image display. Projection display device. (19) A polarizer is arranged in a path of the light from the image display to the projection lens (1)
The projection display device according to 6). (20) A polarization generating element is disposed between the light irradiation unit and the polarization beam splitter (17).
3. The projection display device according to 1. (21) The light emitted from the light irradiator is at least 2
The projection display device according to (16), further including a polarizing beam splitter that transmits light at least once and reflects light at least once. (22) The light emitted from the light irradiating unit is at least 1
The projection display device according to (16), further comprising the polarization beam splitter that transmits light at least once and reflects light at least once. (23) The projection display device according to (16) or (17), wherein the color generation element is the color generation device according to any one of (1) to (10).

[0089]

As described above, according to the present invention, at least three types of wavelength-selective reflective elements that reflect three types of wavelength bands, and a plurality of wavelength-selective reflective elements disposed on the respective light incident sides of the wavelength-selective reflective elements. Since the color generator is constituted by combining the polarization plane rotating element of the above, a mechanical mechanism for rotating the color generator is not required, and the apparatus can be downsized.

Further, according to the projection display apparatus of the present invention, a color image is generated in conjunction with a change in the light by using a reflection type and stationary type color generation element which sequentially outputs colors having different wavelength bands. Since the light is reflected or transmitted by the image display member to be transmitted and further transmitted by the projection lens, the size of the projection display device can be reduced.

[Brief description of the drawings]

FIG. 1A is a configuration diagram of a conventional projection display device, and FIG. 1B is a diagram illustrating a color generation device.

FIG. 2 is a configuration diagram of a basic color generation device according to the first embodiment of the present invention.

FIG. 3 is a first exploded view of the color generation device according to the first embodiment of the present invention.

FIG. 4 is a second exploded view of the color generation device according to the first embodiment of the present invention.

FIG. 5 is a third exploded view of the color generation device according to the first embodiment of the present invention.

FIG. 6 is a fourth exploded view of the color generation device according to the first embodiment of the present invention.

FIG. 7 is a first voltage waveform diagram applied to the color generation device according to the first embodiment of the present invention.

FIGS. 8A to 8C are diagrams illustrating an operation of selectively polarizing red, blue, and green in the color generation device according to the first embodiment of the present invention.

FIG. 9 is a waveform diagram illustrating an output state of a color of light having a different polarization plane among lights reflected from the color generation device according to the first embodiment of the present invention.

FIG. 10 is a diagram illustrating a relationship between an alignment direction and an arrangement of a liquid crystal panel included in the color generation device according to the first embodiment of the present invention.

FIG. 11 is a diagram illustrating a relationship between a phase difference and a wavelength in a liquid crystal panel included in the color generation device according to the first embodiment of the present invention.

FIG. 12 is a diagram illustrating a polarization operation of light by a liquid crystal panel included in the color generation device according to the first embodiment of the present invention.

FIG. 13 is a diagram illustrating a relationship between a voltage applied to a liquid crystal panel and a phase difference included in the color generation device according to the first embodiment of the present invention.

FIG. 14 is a diagram of a second voltage waveform applied to the color generation device according to the first embodiment of the present invention.

FIG. 15 is a table showing a relationship between voltages applied to a plurality of liquid crystal panels constituting the color generation device according to the first embodiment of the present invention and colors to be polarized.

FIG. 16 is a third voltage waveform diagram applied to the color generation device according to the first embodiment of the present invention.

FIG. 17 is a diagram illustrating a change in color of an output of light transmitted through a polarizer among lights output according to the voltage waveform illustrated in FIG. 16;

FIG. 18 is a diagram illustrating an arrangement of a polarization beam splitter that polarizes optical paths of incident light and output light and a color generation device of the color generation device according to the first embodiment of the present invention.

FIG. 19 is a configuration diagram of an optical system of the projection display device according to the first embodiment of the present invention.

FIG. 20 is a perspective view showing an arrangement of a polarizer that also serves as linearly polarized light of incident light and color selection of emitted light in the projection display device according to the first embodiment of the present invention.

FIG. 21 is a chart showing a relationship between a voltage applied to a color generator and a color that does not rotate polarized light when the polarizer shown in FIG. 20 is used.

FIG. 22 is a diagram showing voltage waveforms applied to the color generator when the polarizer shown in FIG. 20 is used.

FIG. 23 is a first example of a voltage waveform diagram applied to a color generator for monochrome display according to the second embodiment of the present invention.

FIG. 24 is a second example of a voltage waveform diagram applied to the color generator for monochrome display according to the second embodiment of the present invention.

FIG. 25 is a diagram illustrating directions of liquid crystal molecules when a voltage is applied to a liquid crystal panel included in a color generation device according to a fourth embodiment of the present invention.

FIG. 26 (a) is a perspective view showing an elliptically polarized state of a liquid crystal panel constituting a color generation device according to a fourth embodiment of the present invention, and FIG. 26 (b) corrects the elliptically polarized light. FIG. 3 is a perspective view in which a retardation film is arranged on one surface of a liquid crystal panel.

FIG. 27 is an exploded view showing an arrangement relationship among a liquid crystal panel, a dichroic mirror, and a retardation film that constitute a color generation device according to a fourth embodiment of the present invention.

FIG. 28 is a configuration diagram of a projection display device according to a fifth embodiment of the present invention.

FIG. 29 is a configuration diagram showing a first example of a projection display device according to a sixth embodiment of the present invention.

FIG. 30 is a configuration diagram illustrating a second example of the projection display device according to the sixth embodiment of the present invention.

FIG. 31 is a configuration diagram showing a third example of the projection display device according to the sixth embodiment of the present invention.

FIG. 32 is a configuration diagram showing a fourth example of the projection display apparatus according to the sixth embodiment of the present invention.

FIG. 33 is a configuration diagram showing a projection display device according to a seventh embodiment of the present invention.

FIG. 34 is a configuration diagram showing a projection display device according to an eighth embodiment of the present invention.

[Explanation of symbols]

1, 2, 3: liquid crystal panel, 4r, 4b, 4g: dichroic mirror, 5, 6: glass plate, 7: polarization beam splitter, 9: retardation film, 10: color generation device (color generation element), 11: Light-emitting source, 12 reflector, 13 polarizer, 14 projection lens, 15 display device, 16 polarizer, 17 aperture, 18 plate-shaped polarization beam splitter, 19 polarization generator.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takakazu Aritake 4-1-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa F-term within Fujitsu Limited (reference) 2H088 EA12 EA15 GA02 HA13 HA18 HA20 HA24 JA17 MA16 MA20 2H091 FA05X FA05Z FA08X FA08Z FA10X FA10Z FA26X FA26Z HA12 LA11 LA15 MA07 5C060 BC05 EA00 HC00 HC24 JA00 JB06 5G435 AA18 BB12 BB17 CC12 DD02 DD04 FF03 FF05 GG01 GG04 GG28 GG46

Claims (5)

[Claims] At least three types of wavelength-selective reflective elements are arranged in parallel and reflect three types of wavelength bands, and a plurality of polarization plane rotation elements are arranged on respective light incident sides of the wavelength-selective reflective elements. A color generation device comprising: 2. The device according to claim 1, wherein adjacent ones of the plurality of polarization plane rotators have a structure in which the polarization plane rotation actions are in opposite directions. Color generator. 3. A plurality of polarization plane rotation elements, wherein a nematic liquid crystal having a homogeneous alignment is sealed therein, and adjacent polarization plane rotation elements are arranged at an inclination of 90 °. Alternatively, the color generation device according to claim 2. 4. The method according to claim 1, wherein the plurality of polarization rotators have a function of birefringence, and a phase difference is λ / 4 (λ; wavelength) or more. Color generator. 5. The plurality of polarization plane rotation elements have a function of changing a phase difference by voltage control, and a phase difference in the wavelength band of reflection by the wavelength selective reflection element is λ / 4 (λ; wavelength). 2. The color generating apparatus according to claim 1, further comprising: a voltage control unit that separately applies one of a nearby voltage and a voltage having a sufficiently small phase difference to the plurality of polarization plane rotation elements.