JP4465071B2 - Color generation apparatus and projection display apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color generation device and a projection display device.
[0002]
[Prior art]
As a color generation element used in a projection display device such as a liquid crystal projector, a three-plate method using three LCD panels, three dichroic mirrors, and a plurality of mirrors for displaying red, green, and blue is generally used. It is. However, the three-plate method has a large number of parts, is difficult to adjust and is an expensive device.
[0003]
In addition, as a time-division color generation element, three areas of red, blue, and green are provided in the disk, and white light is sequentially transmitted through these three areas to convert them into red, blue, and green luminous fluxes. A mechanism for this is described in JP-A-8-51633. A light beam emitted from such a color generation device is applied to a DMD (digital micromirror device) array, thereby displaying a sequential color image.
[0004]
In the case of XGA, for example, the DMD array is a panel in which about 800,000 fine mirrors are arranged in a 17 mm × 13 mm rectangle. Such a fine mirror is formed on the silicon substrate by changing the reflection angle one by one, and is configured to turn on and off the light from the light source. Then, the color tone is controlled by digital ON / OFF to obtain a color image.
[0005]
The optical system of the sequential color image device has a structure as shown in FIG.
In FIG. 1A, light emitted from a light source 101 is reflected by a reflector 102 and then irradiated to a DMD array 105 through a color generation element 103 and a lens 104, and the light reflected by the DMD array 105 is projected onto a projection lens 106. Through the screen (not shown).
[0006]
As shown in FIG. 1 (b), the color generation element 103 is a rotating disk in which red (R), green (G), and blue (B) color filters 103R, 103G, and 103B or a dichroic mirror are combined with them. And is rotated in synchronization with the display of the DMD array 105.
[0007]
[Problems to be solved by the invention]
However, the time-division color generation element 103 is mechanically driven to sequentially change the illumination light and has a large size, which hinders miniaturization of the optical system.
An object of the present invention is to provide a color generation device that can be miniaturized and a projection display device having the color generation device.
[0008]
[Means for Solving the Problems]
  The above issues areA first wavelength selective reflection element that reflects light in the first wavelength band, a second wavelength selective reflection element that reflects light in the second wavelength band, and a third wavelength band that are stacked in the light incident direction. The third to reflectA wavelength selective reflection element;A first polarization plane rotating element that is disposed on the light incident side of the first wavelength selective reflection element and that changes a phase difference by voltage control; the first wavelength selective reflection element; and the second wavelength selective reflection element; Between the first polarization plane rotation element and the second polarization plane rotation element whose phase difference is changed by voltage control, the second wavelength selective reflection element, and the first A third polarization plane rotating element that is arranged with the orientation direction of the second polarization plane rotating element tilted by 90 ° between the third wavelength selective reflecting element and the phase difference is changed by voltage control.WhenA polarizing element that is disposed on the light incident side and the light emitting side of the first polarization plane rotating element and that extracts light of a specific polarization plane; and the first wavelength selective reflection element that is reflected by the first wavelength selective reflection element A first voltage at which a phase difference of light in one wavelength band is λ / 4 (λ: wavelength in the first wavelength band), and the second wavelength band reflected by the second wavelength selective reflection element. The second voltage at which the phase difference of the light becomes λ / 4 (λ: the wavelength in the second wavelength band), the level of the light in the third wavelength band reflected by the third wavelength selective reflection element A third voltage with a phase difference of λ / 4 (λ: wavelength of the third wavelength band), and light of each of the first wavelength band, the second wavelength band, and the third wavelength band Any one of the fourth voltages at which the phase difference of the first polarization plane rotation element and the second polarization polarization is sufficiently eliminated. A rotating element, and a voltage control unit providing separately a third polarization plane rotating elementHaveThe voltage controller applies the first voltage to the first polarization plane rotation element and the second polarization plane rotation element, and also applies the fourth voltage to the third polarization plane rotation element. A first voltage application pattern for applying a voltage, applying the fourth voltage to the first polarization plane rotation element, and applying the second voltage to the second polarization plane rotation element and the third polarization plane rotation element A second voltage application pattern for applying a voltage of, and applying the fourth voltage to the first polarization plane rotation element and the second polarization plane rotation element, and the third polarization plane rotation element Any one of the third voltage application patterns for applying the third voltage to the first polarization plane rotation element, the second polarization plane rotation element, and the third polarization plane is selected. Apply voltage to rotating elementThis is solved by a color generation device characterized by the above.
[0009]
  In the color generation apparatus described above,The first polarization plane rotating element changes a phase difference of light in the first wavelength band by λ / 4 (λ: wavelength in the first wavelength band) when the first voltage is applied. The second polarization plane rotating element changes the phase difference of light in the second wavelength band by λ / 4 (λ: wavelength in the second wavelength band) when the second voltage is applied. When the third voltage is applied, the third polarization plane rotating element sets the phase difference of the light in the third wavelength band to λ / 4 (λ: wavelength in the third wavelength band). ChangeIt may be a thing.
  In the color generation apparatus described above,The first polarization plane rotation element, the second polarization plane rotation element, and the third polarization plane rotation element;The polarization plane rotation element contains a homogeneously aligned nematic liquid crystal.NoYou may make it do.
[0011]
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 light incident side (side closer to the light source) of each wavelength selective reflection element Are combined to form a color generation apparatus.
In this case, the polarization state of each polarization plane rotating element is adjusted, and red, blue, and green light beams are selected and reflected by the wavelength selective reflection element.
[0012]
This eliminates the need for a mechanical mechanism that rotates the color generation device, thereby reducing the size of the device.
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 λ / 4 before and after the passage of light through the liquid crystal panel, or a state in which a phase difference is not generated. Thus, the polarization plane of light in a specific wavelength band can be made different from the polarization plane of other light.
[0013]
Further, according to the projection display device of the present invention, a color image can be displayed in conjunction with a change in the wavelength of the light by using a reflective and stationary color generation element that sequentially selects and outputs light of different wavelengths. Since the image display body to be generated is used and the selected light is reflected or transmitted through the image display body and further transmitted through the projection lens, the projection display apparatus can be reduced in size.
[0014]
In this case, when a polarizing beam splitter is used as an element for polarizing the optical path of light, the optical path can be easily polarized, and can be vertically incident on and reflected from the display element, and the optical system can be miniaturized.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
FIG. 2 is a cross-sectional view showing the basic configuration of the color generation apparatus (color generation element) according to the first embodiment of the present invention.
[0016]
In FIG. 2, first to third liquid crystal panels (polarization plane rotating elements) 1, 2, 3 are arranged in parallel in the light traveling direction in order, and 1, 2 of the first and second liquid crystal panels among them. The first dichroic mirror 4 r is sandwiched between the second and third liquid crystal panels 2 and 3, and the second dichroic mirror 4 b is sandwiched between the second and third liquid crystal panels 2 and 3. A third dichroic mirror 4g is disposed on the side opposite to the position where the second liquid crystal panel 2 is disposed.
[0017]
In the first to third liquid crystal panels 1, 2, and 3, the liquid crystal layers 1b, 2b, and 3b sandwiched between the pair of transparent electrodes 1a, 2a, and 3a are further sandwiched between the pair of transparent substrates 1c, 2c, and 3c, respectively. It has a structure and is produced so that a phase difference of about λ / 4 (λ: wavelength) is generated in transmitted light.
A control signal V is applied to the pair of transparent electrodes 1 a of the first liquid crystal display panel 1.₁Are connected to the pair of transparent electrodes 2a and 3a of the second and third liquid crystal display panels 2 and 3, respectively.₂, V_ThreeIs connected.
[0018]
The first to third liquid crystal panels 1, 2, 3 transmit light without polarization when the high level voltage is applied to the transparent electrodes 1 a, 2 a, 3 a, respectively, while the transparent electrodes 1 a, 2 a , 3a when the low level voltage is applied, the polarization plane of the light is rotated by 90 °. Each of the first to third liquid crystal panels 1, 2 and 3 rotates the polarization plane of light incident from one direction in the forward direction, and reverses the polarization plane of light incident from the opposite direction. It is configured to rotate. Further, the second liquid crystal panel 2 is configured to rotate the polarization plane of the light traveling in the same direction in the reverse direction to the first and third liquid crystal panels 1 and 3.
[0019]
As the material of the liquid crystal layers 1b, 2b, 3b, for example, homogeneously aligned nematic liquid crystal, ferroelectric liquid crystal, VA liquid crystal, 45 ° twisted nematic liquid crystal having a 45 ° orientation direction changed, or the like is used. In the following description, a homogeneously aligned nematic liquid crystal is employed. This liquid crystal, like a λ / 4 phase difference plate, becomes circularly polarized light when transmitted, and when the light is reflected by the dichroic mirror and transmitted again, the plane of polarization rotates 90 ° like the λ / 2 phase difference plate. Is.
[0020]
The liquid crystal layers 1b, 2b, 3b are not particularly shown, but 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 red (R) wavelength and transmits the other wavelengths, and the second dichroic mirror 4b reflects the blue (B) wavelength. The third dichroic mirror 4g is a mirror that reflects the green (G) wavelength and transmits the other wavelengths.
[0021]
The first to third dichroic mirrors 4r, 4b, 4g are composed of, for example, a dielectric multilayer film formed on a glass substrate. As a glass substrate on which such a multilayer film is formed, as shown in FIG. 3, glass substrates 1c, 2c, 3c on the light reflection side constituting the first to third liquid crystal panels 1, 2, 3 are used. Alternatively, as shown in FIG. 4, a glass substrate 5 different from the liquid crystal panels 1, 2, 3 may be used. Forming the dichroic mirrors 4r, 4b, 4g on the glass substrates 1c, 2c, 3c of the liquid crystal panels 1, 2, 3 is effective in reducing the number of parts. In order to prevent exposure of the dichroic mirrors 4r, 4b, 4g, it is effective to use another glass substrate 5.
[0022]
The formation surface of the multilayer film constituting the dichroic mirrors 4r, 4b, 4g 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.
When the glass substrates 1c, 2c, 3c, 5 or between the glass substrates 1c, 2c, 3c and the dichroic mirrors 4r, 4b, 4g are bonded, a transparent adhesive close to the refractive index of the glass is used. As a result, a color generation apparatus with less interface reflection is configured.
[0023]
Incidentally, as shown in FIG. 6, liquid crystal layers 1b, 2b, 3b are sandwiched between four glass substrates 6, and a dichroic mirror (multilayer film) 4r is formed on the reflection side surface of the liquid crystal layers 1b, 2b, 3b. If 4b and 4g are formed, the adhesive layer which adhere | attaches glass substrates will become unnecessary, the amount of light absorption will be decreased, and a thin element will be implement | achieved.
The third dichroic mirror 4g may be a general metal film that reflects the entire visible light region, such as an aluminum film.
[0024]
The dichroic mirror is an example of a wavelength selective reflection element, and other elements may be used instead of the dichroic mirror.
The arrangement of the first to third dichroic mirrors 4r, 4b, and 4g is not limited to the order described above, and it is desirable to match 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 the color with the highest intensity among red, blue, and green in the light spectrum is disposed behind the light incident direction, and the dichroic mirror that reflects the color with the lowest intensity. Is preferably disposed in front of the light incident direction.
[0025]
For example, if the light source is an ultra-high pressure mercury lamp, the light intensity is high in the order of green, blue, and red (G> B> R). Therefore, as described above, for red reflection, blue reflection, and green reflection in the direction away from the light source. Dichroic mirrors are arranged in the order for. When the light source is a metal halide lamp or halogen lamp, the light intensity is high in the order of green, red, and blue (G> R> B). Therefore, for blue reflection, red reflection, and green reflection in the direction away from the light source. Place dichroic mirrors in the order for.
[0026]
Color generation method
Next, a method for generating red, blue and green light by the color generating apparatus having the above configuration will be described.
In the color generation device, the transparent electrodes 1a, 2a, 3a of the first to third liquid crystal panels 1, 2, 3 are provided with a power source V₁, V₂, V_ThreeFor example, AC pulse voltages Vr, Vb and Vg shown in FIG. 7 are applied.
[0027]
When the pulse voltages Vr, Vb, Vg are equal to or higher than a certain voltage (generally about 5V), the liquid crystal layers 1b, 2b, 3b become isotropic, and the action of rotating the polarization plane disappears. Accordingly, it is possible to rotate the polarization plane of the light beam reflected by the dichroic mirror by adjusting the voltage value. By sequentially changing the liquid crystal layer to be applied, it becomes possible to sequentially emit light in a necessary wavelength band from the first liquid crystal panel 1.
[0028]
A liquid crystal of a general liquid crystal panel that generates a phase difference of λ / 2 in order to generate a phase difference of λ / 4 in the liquid crystal layers 1b, 2b, 3b of the first to third liquid crystal panels 1, 2, 3 The layer is thinner than the layer, and high-speed driving is possible. A ferroelectric liquid crystal capable of realizing ultra-high speed driving may be used. It can also be realized by nematic liquid crystal and VA liquid crystal capable of vertical alignment. If a liquid crystal and an orientation equivalent to a λ / 4 retardation plate can be realized, it can be applied to this color generation element.
[0029]
The pulse voltages Vr, Vb, Vg are, for example, 60 Hz. Further, it is desirable to apply an alternating current as in the case of general liquid crystal driving.
Next, each of the 0th to 1/3 period, the 1/3 to 2/3 period, and the 2/3 to 3/3 period will be described.
(i) 0 to 1/3 period
First, as shown in FIG. 7, light reflection and polarization as shown in FIG. 8 (a) are performed in the first 1/3 period of the pulse voltages Vr, Vb, Vg.
[0030]
That is, as shown in FIG. 8A, 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 off, the third liquid crystal panel 3 The voltage application between the pair of electrodes 3a is turned on.
In this period, the white light is linearly polarized by a polarizing element to be described later and is irradiated toward one surface of the first liquid crystal panel 1.
[0031]
As shown in FIG. 8 (a), the red light beam (R) included in the white light is circularly polarized by the first liquid crystal panel 1 in the forward rotation and transmitted with a phase difference of λ / 4. Irradiated to the dichroic mirror 4r. In the first dichroic mirror 4r, the circularly polarized light of the red light beam is reflected and inverted. The reflected red light beam is again transmitted through the first liquid crystal panel 1 and reversely rotated to be linearly polarized. As a result, the red light beam returned from the one surface of the first liquid crystal panel 2 is rotated by 90 ° with respect to the incident red light beam, thereby becoming light having a polarization plane perpendicular to the paper surface, for example. Therefore, a red light beam can be selectively extracted by a polarizing element that transmits light having a polarization plane perpendicular to the paper surface.
[0032]
Further, as shown in FIG. 8 (a), the blue luminous flux (B) contained in the white light is transmitted through the first liquid crystal panel 1, circularly polarized by the forward rotation, and transmitted as it is. The light passes through the first dichroic mirror 4r. Further, the blue light beam transmitted through the first dichroic mirror 4r is transmitted through the second liquid crystal panel 2 and reversely rotated to return to the original linearly polarized light, and is irradiated to the second dichroic mirror 4b as it is. Is done. The blue light beam reflected by the second dichroic mirror 4b is transmitted in the order of the second liquid crystal panel 2, the first dichroic mirror 4r, and the first liquid crystal panel 1. Since the second liquid crystal panel 2 and the first liquid crystal panel 1 are circularly and linearly polarized by reverse rotation, blue light emitted from one surface of the first liquid crystal panel 1 is incident from the one surface. It becomes linearly polarized light at the same angle.
[0033]
Further, as shown in FIG. 8A, the green light beam (G) included in the white light is in the same state as the blue light beam, and the first and second liquid crystal panels 1 and 2 and the first dichroic mirror 4r. Is transmitted to the second dichroic mirror 4b. The green light beam 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 luminous flux passes through the third liquid crystal panel 3 and the second dichroic mirror 4b as it is, and then, similarly to the blue luminous flux, the second liquid crystal panel 2 and the first dichroic mirror 4r. The first liquid crystal panel 1 is sequentially transmitted. Since the green light beam emitted from one surface of the first liquid crystal panel 1 is circularly and linearly polarized by the reverse rotation in the second liquid crystal panel 2 and the first liquid crystal panel 1, It has the same plane of polarization as that incident on the panel 1.
[0034]
As described above, the red light beam emitted from the first liquid crystal panel 1 is light having a polarization plane different from that of the blue and green light beams by 90 °. It is possible to sort by element.
Since light other than red, blue, and green light beams passes through the first to third liquid crystal panels and the first to third dichroic mirrors 4e, 4b, and 4g, as shown in FIG. 8 (a). There is no return to the one surface side of the first liquid crystal panel 1.
[0035]
(Ii) 1/3 to 2/3 cycle
First, in the 1/3 to 2/3 period of the pulse voltages Vr, Vb, and Vg shown in FIG. 7, light reflection and polarization as shown in FIG. 8B are performed.
That is, in FIG. 8B, the voltage application to the pair of transparent electrodes 2a and 3a of the second and third liquid crystal panels 2 and 3 is turned off, while the pair of the first liquid crystal panel 1 is paired. The voltage application to the transparent electrode 1a is turned on. In this case, the white light is linearly polarized by the first linear polarizing plate and irradiated toward one surface of the first liquid crystal panel 1. The linearly polarized light propagates on a plane of polarization parallel to the paper surface, for example.
[0036]
As shown in FIG. 8 (b), the red light beam (R) contained in the white light is irradiated on the first dichroic mirror 4r after passing 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 is again transmitted through the first liquid crystal panel 1 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. Accordingly, the red light beam is prevented from traveling by a polarizing element that transmits only linearly polarized light perpendicular to the paper surface.
[0037]
Further, as shown in FIG. 8B, the blue light beam (B) contained in white is transmitted through the first liquid crystal panel 1, the first dichroic mirror 4r, and the second liquid crystal panel 2 to be second. Is reflected by the dichroic mirror 4b. The blue light beam passes through the second liquid crystal panel 2 and is circularly polarized by reverse rotation, and is further reflected and inverted by the second dichroic mirror 4b. The reflected blue light beam passes through the second liquid crystal panel 2 and is circularly polarized by forward rotation, thereby becoming linearly polarized light rotated by 90 ° with respect to the state incident on the first liquid crystal panel 1. In this state, the light passes through the first dichroic mirror 4r and the first liquid crystal panel 1 and is emitted to one surface side of the first liquid crystal panel 1.
[0038]
Further, as shown in FIG. 8 (b), the green luminous flux (G) contained in white is converted into the first liquid crystal panel 1, the first dichroic mirror 4r, the second liquid crystal panel 2, and the second dichroic mirror. 4b passes through 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 reverse rotation by the second liquid crystal panel 2, but is returned to the original linearly polarized light by forward rotation by the third liquid crystal panel 3, so that the third dichroic mirror 4g Reflected in the state of linear polarization. Further, the green light beam reflected by the third dichroic mirror 4 g travels toward the first liquid crystal panel 1, but when passing through the second and third liquid crystal panels 2 and 3, The circularly polarized light and the linearly polarized light are rotated to return to the original state and come out from one surface side of the first liquid crystal panel 1.
[0039]
As described above, the blue luminous flux emitted from the first liquid crystal panel 1 is linearly polarized light that differs by 90 ° from the red luminous flux and the green luminous flux, and therefore can be selectively extracted.
Since light other than the red, blue, and green light beams passes through the first to third liquid crystal panels 1, 2, and 3 and the first to third dichroic mirrors 4r, 4b, and 4g, FIG. As shown in FIG. 2, the first liquid crystal panel 1 does not return to the one surface side.
[0040]
(iii) 2/3 to 3/3 cycle
First, as shown in FIG. 7, light reflection and polarization as shown in FIG. 8 (c) are performed in the 2/3 to 3/3 period of the pulse voltages Vr, Vb, Vg.
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 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 irradiated toward one surface of the first liquid crystal panel 1. The linear polarization plane is, for example, parallel to the paper surface.
[0041]
As shown in FIG. 8 (c), the red light beam (R) contained in the white 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 is propagated on the same polarization plane as the incident red light beam.
[0042]
Further, as shown in FIG. 8 (c), the blue luminous flux (B) contained in the white light is not rotated and the first liquid crystal panel 1, the first dichroic mirror 4r, the second The blue light beam transmitted through the 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.
[0043]
Further, as shown in FIG. 8C, the green light beam (G) contained in the white light is converted into the first liquid crystal panel 1, the first dichroic mirror 4r, the second liquid crystal panel 2, and the second dichroic. The light passes through the 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 forward rotation by the third liquid crystal panel 3, but reversely reflected when being reflected and inverted by the third dichroic mirror 4g and then transmitted through the third dichroic mirror 4g. The light is linearly polarized by rotation to become linearly polarized light. The polarization plane of the blue luminous flux is rotated by 90 ° with respect to the polarization plane of the green luminous flux incident on the first liquid crystal panel 1. The green light beam in the linearly polarized state is then emitted from the one surface side of the first liquid crystal panel 1 without further rotating the polarization plane.
[0044]
As described above, the green light beam emitted from the first liquid crystal panel 1 is linearly polarized light that is 90 ° different from the red and blue light beams, and can be selectively extracted.
Since light other than the red, blue, and green light beams passes through the first to third liquid crystal panels 1, 2, 3 and the first to third dichroic mirrors 4r, 4b, 4g, FIG. 8 (c). As shown in FIG. 2, the first liquid crystal panel 1 does not return to the one surface side.
[0045]
According to the color generation apparatus as described above, red, blue, and green light can be periodically emitted as shown in FIG. 9 without requiring a large-scale structure such as a vaporizer-like rotation mechanism. become. The linear polarization plane of light incident on the first liquid crystal panel 1 is not limited to being parallel to the paper surface as described above.
LCD panel layout
The first to third liquid crystal panels 1, 2, 3 are arranged as follows.
[0046]
The second liquid crystal panel 2 disposed between the first and third liquid crystal panels 1 and 3 seems to produce an action opposite to the action of the first and third liquid crystal panels 1 and 3 rotating the polarization plane. Is arranged. That is, when the first and third liquid crystal panels 1 and 3 change the linearly polarized light into the circularly polarized light, the second liquid crystal panel 2 is arranged to change the circularly polarized light into the linearly polarized light, or When the three liquid crystal panels 1 and 3 change the circularly polarized light into the linearly polarized light, the second liquid crystal panel 2 is arranged to change the linearly polarized light into the circularly polarized light.
[0047]
For example, when the liquid crystal panels 1, 2 and 3 have 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 tilted orientation direction is adopted, the liquid crystal layer 2b of the second liquid crystal panel 2 is tilted by θ + 90 ° or 90 ° -θ (for example, 135 °), and the liquid crystal layer 3b of the third liquid crystal panel 3 is tilted by θ (for example, 45 °). The direction. These alignment directions are determined by adjusting the rubbing direction of the alignment film sandwiching the liquid crystal layer.
[0048]
By the way, from the relationship between the wavelength of the general liquid crystal and the refractive index dispersion, the wavelength and the phase difference of the liquid crystal layer are as shown in FIG. For example, when a liquid crystal layer having a phase difference of λ / 4 (π / 2) at a wavelength of green (G) is produced, the phase difference is smaller than λ / 4 at the wavelength of red (R) in the liquid crystal layer, and vice versa. In addition, the phase difference is larger than λ / 4 at the wavelength of blue (B). According to such a liquid crystal layer, the amount of polarization rotation of the light beam transmitted through the liquid crystal layer differs between the wavelengths, and the variation in the polarization amount of each wavelength transmitted through the plurality of liquid crystal layers further increases.
[0049]
For example, when the alignment directions of the first to third liquid crystal panels 1, 2, 3 are all made the same, or when the polarization amount of the liquid crystal panels 1, 2, 3 is adjusted to one wavelength, the dichroic mirror is reflected. The amount of rotation of the light beam varies from wavelength to wavelength, making it difficult to selectively separate and extract only light of a specific wavelength.
Therefore, as shown in FIGS. 10 and 12, when the alignment directions are staggered, when the linearly polarized light is circularly polarized by two liquid crystal panels and then returned to the linearly polarized light, there is a variation in the phase difference of each wavelength. All are canceled. As a result, an ideal amount of polarization rotation can be added at each wavelength. That is, for all wavelengths, the light beam obtained by converting linearly polarized light into circularly polarized light can be completely returned to linearly polarized light after that, and it becomes easy to separate and extract light of a specific wavelength by the polarizing element.
[0050]
Voltage applied to the liquid crystal panel voltage
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 all the same nematic liquid crystals are used in the first to third liquid crystal panels, a method of generating a phase difference of λ / 4 (π / 2) for all of the red light beam, the blue light beam, and the green light beam. Is described below.
[0051]
First, three liquid crystal panels that produce a phase difference by λ / 4 of the red light beam having the longest wavelength are manufactured.
Then, a reference voltage corresponding to the colors of red, blue, and green is applied to a pair of electrodes that sandwich the liquid crystal layer in the first to third liquid crystal panels, respectively, and circularly polarized with a phase difference of λ / 4. That is, in a liquid crystal panel having the same structure in which nematic liquid crystal is sealed, the relationship between the applied voltage value and the phase difference for each of the red, blue, and green light fluxes is as shown in FIG. The phase difference between the blue and green light beams can be set to λ / 4. The voltage for sufficiently eliminating the phase difference is Vm regardless of the color difference.
[0052]
Here, a reference voltage that causes a phase difference of λ / 4 to occur in the red luminous flux is V_r0And a reference voltage that causes a phase difference of λ / 4 in the blue luminous flux is V_b0And a reference voltage for generating a phase difference of λ / 4 in the green luminous flux is V_g0And
Therefore, when the color generating device shown in FIG. 2 is configured using three liquid crystal panels having the same structure, the voltage shown in FIG. 7 is changed as shown in FIG. 14, and red, blue, green When one of the luminous fluxes is selected, the voltage values applied to the electrodes of the first to third liquid crystal panels are combined as shown in FIG. 15, and as a result, FIG. 8 (a) to FIG. 8 (c). The same polarization as shown in) can be performed.
[0053]
Further, 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 panel of the liquid crystal panel, that is, the gap between the transparent substrates 1c (2c, 3c) is slightly thickened to ensure 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 that feeds back monitor data such as a sensor.
[0054]
Further, when the response speed of the liquid crystal layers 1b, 23b, and 3b of the liquid crystal panel is slow, as shown in FIG. The luminous flux of each color rotated by .degree. Can be synchronized with the display of a display element such as a DMD array as shown in FIG.
When the voltage shown in FIG. 7 is applied to the transparent electrodes 1a, 2a, 3a of the first to third liquid crystal panels 1, 2, 3 shown in FIG. 2, for example, as shown in FIG. A prism-shaped polarizing beam splitter (PBS) 7 is arranged as a polarizer on one surface side of one liquid crystal panel 1. Thus, when white light is incident on the front surface of the polarizing beam splitter 7, red, blue, and green light beams generated by the light generation device 10 can be sequentially extracted to the side of the polarizing beam splitter 7.
[0055]
When a projection display device is configured using such a polarizing beam splitter 7 and the color generation device 10, a configuration as shown in FIG. 19 is adopted.
In FIG. 19, a polarizing beam splitter 7 is formed by bonding the bottom surfaces of two right-angle prisms, for example, and transmits linearly polarized light parallel to the paper surface to the boundary between the bottom surfaces. A polarizing film 7a that reflects light other than the above is formed.
[0056]
A white light source 11 is arranged on the opposite side of the polarization beam splitter 7 from the color generation device 10. A reflector 12 is disposed 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 irradiated to the color generation device 10 through the polarization beam splitter 7. It has become.
In the polarizing 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 polarizing film 7a. The polarizer 13 has a structure that transmits, for example, only a light beam having a polarization plane parallel to the paper surface and absorbs other light. A projection lens 14 is disposed in front of the light traveling direction of the polarizer 13.
[0057]
Further, a display element 15 such as a DMD array is disposed on the opposite side of the polarizing beam splitter 7 from the polarizing element 13. The display element 15 is structured to reflect an incident light beam by rotating it by 90 °.
Of the polarization 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 generation device 10 is the first surface. The third surface is the fourth surface.
[0058]
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 is applied to the polarizing film 7a. Of the white light irradiated to the polarizing film 7 a, light parallel to the paper surface is transmitted through the polarizing film 7 a and irradiated to the color generation device 10, while the other light is reflected and absorbed by the polarizer 13.
[0059]
The white light irradiated to the color generation device 10 selects and reflects red, blue and green light fluxes by the liquid crystal panels 1, 2, 3 and the dichroic mirrors 4r, 4b, 4g and returns them to the polarizing film 7a. Two light fluxes of red, blue, and green reflected by the color generation device 10 become, for example, a polarization plane parallel to the paper surface, and the remaining one light beam is polarized perpendicular to the paper surface.
[0060]
Of the red, blue, and green light fluxes generated by the color generation device 10, the light flux having a polarization plane perpendicular to the paper surface is reflected by the polarizing film 7a and applied to the display device 15, and further the polarization plane parallel to the paper surface. The light passes through the polarizing film 7a and returns to the light source 11. The light beam applied to the display element 15 is reflected by being rotated by 90 ° by the display element 15, and further travels straight to the screen S through the polarizing film 7 a, the polarizer 13, and the projection lens 14.
[0061]
The wavelength band (color) that reflects the polarizing film 7a is sequentially switched in synchronization with the change of the display elements that are sequentially displayed sequentially, and the display element 15 is sequentially irradiated with the light flux of the necessary wavelength band (color). . 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 it is not desired to use the prism, as shown in FIG. 20, it is parallel to the front surface of the color generation apparatus 10 and is only in one direction. A polarizer 16 having a transmission axis is disposed in front of it, and the voltages Vr, Vb, Vg as shown in FIGS. 21 and 22 are applied to the transparent electrodes 1a, 1a, 3b of the first to third liquid crystal panels 1, 2, 3. 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. .
[0062]
According to this, as shown in FIG. 20, a polarizer for linearly polarizing when white light is incident can be used as a polarizer for color selection, and the configuration of the color generation device is simple and inexpensive. Can be.
The color generation device may include a polarizer as a concept or may not include a polarizer.
(Second Embodiment)
In the first embodiment, since three colors are extracted in a time-division manner by the color generation device, 1/3 light flux is used and light of other wavelengths is lost.
[0063]
However, in a display device such as a projector, monochrome (monaural) display may be performed. Therefore, a method for effectively using the luminous flux in monochrome display will be described below.
In the projection display device provided with the polarization beam splitter 7 shown in FIG. 19, if all the RGB luminous fluxes are linearly polarized light rotated by 90 °, all the RGB luminous fluxes are irradiated onto the projection lens 14 and light. Loss is reduced.
[0064]
Therefore, as shown in FIG. 23, the voltage applied to the transparent electrode 1a of the first liquid crystal panel 1 is V_g0Then, with the voltage applied to the transparent electrodes 2a and 3a of the second and third liquid crystal panels 2 and 3 as Vm, all the light can be rotated by 90 ° and emitted from the polarization beam splitter 7.
In this case, the voltage V is applied to the transparent electrode 1a of the first liquid crystal panel 1._r0Not the voltage V_g0Is applied to the intermediate voltage V_g0This is to reduce the difference in rotation amount due to the difference in RGB wavelength.
[0065]
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 1 and 2 are used as shown in FIG. , 3 when the same voltage Vm is applied to each of the transparent electrodes 1a, 2a, 3a, all the RGB luminous fluxes pass through the polarizer 16 and enter the color generating apparatus 10, and then the first to third as they are. The light is reflected by the dichroic mirrors 4r, 4b, 4g and emitted from the polarizer 16. In this case, since there is no polarization by the liquid crystal panels 1, 2, 3, light loss is reduced.
[0066]
Note that it is possible to take intermediate between the color display described in the first embodiment and the monochrome display of the present embodiment. Adjustment is possible by a combination of voltage application.
(Third embodiment)
In order to use the color generation apparatus described in the first and second embodiments for a color display apparatus such as a color projector, color change must be realized at 180 Hz. The human eye can see the image naturally up to about 60 Hz due to the afterimage effect. Therefore, in order to realize a color within 60 Hz, a high color switching speed of 180 Hz (5.5 ms), which is three times as high, is required. It is known that the response speed of the liquid crystal is inversely proportional to the square of the liquid crystal gap.
[0067]
Generally used nematic liquid crystal has a response speed of about 20 ms with a distance between electrodes 1a (2a, 3a) of 5 μm gap, and in order to realize 180 Hz, 5 μm / √ (20 ms / 5.5 ms) ≈2 This can be realized with an interelectrode gap of 6 μm or less.
Therefore, in order to change the color at a response speed of 180 Hz, it is necessary to set the gap between the electrodes, that is, the thickness of the liquid crystal layer to 2.6 μm or less.
(Fourth embodiment)
In this embodiment, a technique for improving optical characteristics is shown.
[0068]
If the rotation of the polarization is not appropriate and the linearly polarized light is in the elliptically polarized state, noise is included or a necessary light beam is cut when the color is separated and extracted by the polarizer. Therefore, in the method of the above-described embodiment, it is desired to completely erase the phase difference caused by the liquid crystal layer when a voltage is applied (Vm) for making the phase difference caused by the liquid crystal layer zero.
However, as shown in FIG. 25, there are liquid crystal molecules that are firmly aligned at the interface between the liquid crystal layer 1 b and the alignment film 8, and it is difficult to completely eliminate the phase difference by applying a certain voltage. This characteristic also appears in FIG.
[0069]
Applied voltage V_mAlthough the phase difference due to the liquid crystal layer is reduced by increasing the ratio, it is not practical because it places a burden on the liquid crystal driving circuit. A method that can be improved is shown in FIG.
In FIG. 26 (a), a high level voltage V is applied to the electrode 1a of the liquid crystal panel 1._mEven if is applied, linearly polarized light is not transmitted with a phase difference of zero, but becomes a state of elliptically polarized light due to the remaining phase difference.
[0070]
Therefore, as shown in FIG. 26 (b), the phase difference film 9 that gives the remaining phase difference a reverse rotation with a slight phase difference is disposed on the liquid crystal panel 1 (2, 3) to cancel the residual phase difference.
The retardation film 9 can be produced by stretching a polymer. The direction of the arrow on the retardation film 9 in FIG. 26 (b) indicates the stretching direction or the stretching vertical direction. The arrangement angle of the arrow has an optimum angle depending on the phase difference amount.
[0071]
When the phase difference of the retardation film 9 is large, the optimum arrangement angle is obtained by bringing the arrow close to parallel or perpendicular to the direction of incident polarized light.
On the other hand, if the phase difference is small, the residual phase difference amount can be optimally canceled by placing the arrow in the vicinity of 45 ° with respect to the incident polarized light.
What is important in the arrangement of the phase difference film 9 is an arrangement in which the rotation direction of the linearly polarized light due to the residual phase difference is reversed and canceled. Although it is possible to produce linearly polarized light by positive rotation, a large amount of rotation of polarized light varies depending on the wavelength. For example, in the arrangement for giving the reverse rotation, the direction of the arrow in the rubbing direction of the alignment film of the liquid crystal panel 1 (2, 3) shown in FIG. Assuming that the arrow direction of the phase difference film 9 is a high refractive index direction, it can be realized by arranging the high refractive index directions in opposite directions with respect to the incident polarization direction. The retardation film 9 for correction can be substituted with a thin slice of a birefringent crystal plate. Although it is conceivable to arrange a correction liquid crystal panel, it is not practical because the absorption loss is large and the cost is high.
[0072]
FIG. 27 shows a schematic diagram in which the retardation films 9a to 9c for correction are arranged on all of the first to third liquid crystal panels 1, 2, and 3.
The left side of FIG. 27 is an incident surface.
Note that the residual phase difference of the second or third liquid crystal panel 2 or 3 is a direction to cancel with the residual phase difference of the first or second liquid crystal panel 1 or 2 and may be omitted in this case.
[0073]
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. Can be omitted.
Since the third liquid crystal panel 3 can be corrected by fine adjustment of the voltage applied to the first and second liquid crystal panels 1 and 2, the correction retardation film may be omitted. However, 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 at least the light incident side of the liquid crystal panel 1 is provided with a retardation film. .
(Fifth embodiment)
In the first embodiment, as shown in FIG. 19, the display device 15 and the polarizer 13 are arranged with the polarization beam splitter 7 interposed therebetween. In such a configuration, since the projection lens 14 is irradiated with the light beam that has passed through the polarization beam splitter 7 three times, it is desired to reduce the light loss caused by the polarization beam splitter 7. In this case, it is preferable to adopt a configuration as shown in FIG.
[0074]
In FIG. 28, the bottom surfaces of the 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 light of a polarization plane parallel to the paper surface. And a polarization plane 7b that reflects other light.
The light source 11 is disposed so as to face the color generation device 10 via the polarization beam splitter 7. A display device 15, a polarizer 13, and a projection lens 14 are sequentially arranged in the traveling direction of light emitted from the color generation device 10 and reflected by the polarization plane 7 b.
[0075]
The color generation device 10 has the same structure as that of the first embodiment. Further, as the display device 15, a DMD array is not applied, and a transmission type such as a liquid crystal display device is used.
According to such an arrangement, the white light emitted from the light source 11 passes through the polarization beam splitter 7 and is polarized into a light beam having a polarization plane parallel to the paper surface and is irradiated to the color generation device 10. Then, in the color generation device 10, as described in the first embodiment, the red, blue, and green light beams of the white light are reflected and returned to the polarization beam splitter 7. Since the red, blue, and green light reflected from the color generation device 10 is sequentially linearly polarized in a plane perpendicular to the paper surface, the polarization plane 7b of the polarization beam splitter 7 is polarized by the color generation device 10. Is reflected through the display device 15, the polarizing element 13, and the projection lens.
[0076]
Accordingly, since the light emitted from the light source 11 passes through the polarization beam splitter 7 twice and reaches the projection lens 14, light loss is reduced as compared with the first embodiment.
(Sixth embodiment)
As for the characteristics of the polarizing beam splitter 7 in the first embodiment, the light beam is most preferably parallel light.
[0077]
When a diverging or converging light beam enters the polarizing beam splitter 7, the incident angle is not uniform, so that the polarization separation characteristic of the polarizing beam splitter 7 is deteriorated. Therefore, the reflector 12 disposed around the light source 11 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. Therefore, if a parallel light beam is used, the display element 15 cannot be efficiently irradiated with the light beam.
[0078]
Therefore, by using the convergent light that is opposite to the direction in which the polarization beam splitter 7 has good characteristics, it becomes possible to efficiently irradiate the display element with the light beam.
If the polarization beam splitter 7 has a change in incident angle of about ± 10 °, a polarization characteristic of about 90% can be secured. Even with convergent light, if the change in incident angle is within ± 10 °, there is no problem in the characteristics, and the light utilization efficiency can be increased.
[0079]
FIG. 29 shows the progress of light when such convergent light is emitted from the reflector 12. In FIG. 29, if the condensing point of the converged light by the reflector 12 is set in the vicinity of the display element 15 through the polarization beam splitter 7 or the like, the display device 15 smaller than the color generation device 10 can be handled.
When such convergent light is used, as shown in FIG. 30, noise light can be prevented from entering the projection lens 14 by providing a diaphragm (aperture) 17 in the vicinity of the projection lens 14. That is, when the focal point 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 prevented from entering the projection lens 14. Thereby, the contrast of an image can be improved and a good quality image can be obtained.
[0080]
By the way, such unnecessary light (noise light) is, for example, a light beam as indicated by a broken line in FIG. That is, the polarization separation characteristic by the polarization 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 surface perpendicular to the paper surface, is reflected by the polarization surface 7 b of the polarization beam splitter 7 and irradiated to the polarizer 13. Absorbed. However, several percent of the reflected light flux is transmitted through the polarizing element 13.
[0081]
Therefore, as shown in FIG. 31, the polarizing beam splitter 7 is arranged in a state slightly rotated from the center. According to this, the direction of the unnecessary light reflected by the polarizing beam splitter 7 and the display light beam reflected by the display element 15 are changed.
In general, the projection lens 14 of a projector can capture an angle of light of several degrees. Unless an unrealistic large-diameter projection lens is used, projection is impossible when the incident angle of light is ± 10 ° or more. Therefore, when the incident angle is ± 10 ° or more, the capture angle can be further reduced by using a projection lens having a small aperture size or a projection lens aperture.
[0082]
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, and it is preferable to adopt such a configuration if there is little unnecessary light.
However, in order to reduce unnecessary light incident on the polarizer 13, as shown in FIG. 31, the polarizing beam splitter 7 is tilted so that the incident angle to the display element 15 is within 10 °, that is, several degrees. It is preferable.
[0083]
When the incident angle to the display element is within ± 10 °, the polarization plane (reflection surface) 7b inside the polarization beam splitter 7 is 45 with respect to the incidence plane of the color generation device 10 as shown in FIG. The optical axes of the display element 15, the polarizer 13, and the projection lens 14 may be tilted several degrees with respect to the incident angle of the light flux on the display element 15.
[0084]
When such a structure is adopted, the light beam from the light source 11 is perpendicular to the seven incident surfaces of the polarization beam splitter, so that a smaller polarization beam splitter can be used as compared with FIG. Become a system.
(Seventh embodiment)
In the optical system of the above-described embodiment, since a polarizing beam splitter using a right-angle prism is used, polarization separation characteristics are good, and high image quality and high brightness can be realized. become.
[0085]
Therefore, as shown in FIG. 33, a flat polarizing beam splitter 18 can be used instead of the right-angle prism. As the flat polarizing beam splitter 18, for example, a polarizing plate having a multilayer structure formed on a glass substrate, or a film-like polarization separating element is used. As a polarization separation element, for example, there is a trade name D-BEF manufactured by 3M.
[0086]
In FIG. 33, the polarization beam splitter 18 is polarized by the polarization beam splitter of the first embodiment in a state where one surface of the flat polarization beam splitter 18 is inclined by 45 ° with respect to the traveling direction of the light beam emitted from the reflector 12. It arrange | positions in the position of the surface 17a.
Since such a flat polarizing beam splitter 18 is inexpensive, the cost of the entire optical system can be reduced.
(Eighth embodiment)
Conventional liquid crystal projectors have two polarizers or one round-trip transmission using reflection. A polarizer absorbs about 10% of a light beam having a required polarization plane. Therefore, the smaller the number, the better the transmittance and the higher the brightness. However, if a light source having a high output is used, all the unnecessary light fluxes are absorbed by one polarizer, and its durability becomes a problem.
[0087]
Therefore, in order to increase the durability, for example, as shown in FIG. 34, a polarization generating element 19 is interposed between the polarization beam splitter 7 and the light source 11, and the polarization generating element 19 changes the polarization plane parallel to the paper surface. Light is selectively applied to the polarization beam splitter 7. As the polarized light generating element 15, a polarizer, a film-like polarized light separating element or the like is used.
[0088]
According to this, since the polarization generating element 19 absorbs and reflects a light beam having an unnecessary polarization plane, only the light beam reflected from the display element 15 enters the polarizing element 13 on the projection lens 14 side. Therefore, the durability of the polarizing element 15 is improved.
In each of the embodiments described above, the polarization plane horizontal to the paper surface may be a vertical polarization plane, and the vertical polarization plane may be a horizontal plane.
{Appendix}
(1) having at least three kinds of wavelength selective reflection elements arranged in parallel and reflecting three kinds of wavelength bands, and a plurality of polarization plane rotation elements arranged on the respective light incident sides of the wavelength selective reflection elements A color generation apparatus characterized by the above.
(2) The color generation according to (1), wherein the polarization plane rotation elements adjacent to each other among the plurality of polarization plane rotation elements have a structure in which the polarization plane rotation functions are in opposite directions. apparatus.
(3) A plurality of the polarization plane rotating elements, wherein nematic liquid crystal with homogeneous orientation is enclosed, and the alignment directions of the adjacent polarization plane rotating elements are inclined by 90 ° (1) or ( 2) The color generation device described in 2).
(4) The color according to (1) or (2), wherein the plurality of polarization rotation elements have a birefringence function 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). And a voltage control unit that separately supplies a plurality of the polarization plane rotation elements to each of the voltage and the voltage at which the phase difference is sufficiently small, the color generation device according to (1).
(6) The color generation device according to (5), wherein the polarization plane rotation element is a liquid crystal panel, and a phase difference switching speed by the voltage control unit is 180 Hz or more.
(7) The color generation device according to (3) or (7), wherein the polarization plane rotation element is filled with nematic liquid crystal and a liquid crystal gap is 2.6 μm or less.
(8) The color generation device according to (1), wherein the plurality of polarization plane rotation elements have a function of making a monochrome display or a monochrome display close.
(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 disposed at a light incident or exit portion of the polarization plane rotating element. apparatus.
(10) The color generation according to claim 10, wherein the retardation film or the birefringent crystal plate has a direction of polarization plane rotation opposite to a direction of polarization plane rotation by the polarization plane rotation element. apparatus.
(11) One of the three dichroic mirrors is a metal film reflector, and the color generating device according to (1).
(12) The plurality of polarization plane rotation elements are made of liquid crystal sandwiched between a pair of transparent plates, and the dichroic mirror has a structure in which a reflective film is formed on a transparent substrate, and the polarization plane rotation elements and the dichroic The color generation apparatus according to (1), wherein the mirror is bonded via an adhesive layer.
(13) The plurality of polarization plane rotation elements include a liquid crystal layer sandwiched between a pair of transparent plates, and the dichroic mirror is formed on one surface of each of the transparent plates of the plurality of polarization plane rotation elements. (1) The color generation apparatus according to (1), wherein the color generation device includes a reflection film, and the polarization plane rotation elements are integrated with the dichroic mirror with an adhesive layer interposed therebetween.
(14) The plurality of polarization plane rotating elements include a liquid crystal layer sandwiched between a pair of transparent plates, and the dichroic mirror is sandwiched between one of the liquid crystal layer of the polarization plane rotating elements and the transparent plate. The color generation apparatus according to (1), wherein the polarization plane rotating elements are bonded to each other through an adhesive layer.
(15) The plurality of polarization plane rotating elements are integrally configured with a liquid crystal layer sandwiched between the plurality of transparent substrates, and the dichroic mirror is formed between the liquid crystal layer and the transparent plate. The color generation device according to (1), which is characterized.
(16) A reflective color generation element that sequentially generates light of a plurality of wavelength bands by reflecting light from the light irradiation unit, and the light of the plurality of wavelength bands irradiated from the color generation element is sequentially irradiated A projection display device comprising: an image display body that generates a color image in conjunction with changes in light in the plurality of wavelength bands; and a projection lens that expands the light reflected or transmitted through the image display body.
(17) The color generation element has a function of individually modulating the polarization planes of the light in the plurality of wavelength bands, and modulates the polarization plane of the light output from the color generation element, thereby specifying a specific wavelength. The projection display device according to (16), further comprising a polarization beam splitter that irradiates the image display body with light in a band.
(18) The axis of the light incident on the image display body is set at an angle within 10 ° from the vertical direction with respect to the display surface of the image display body. Projection display device.
(19) The projection display device according to (16), wherein a polarizer is disposed in the light path from the image display body to the projection lens.
(20) The projection display device according to (17), wherein a polarization generating element is disposed between the light irradiation unit and the polarization beam splitter.
(21) The projection display device according to (16), further comprising a polarization beam splitter that transmits the light emitted from the light irradiation unit at least twice and reflects the light at least once.
(22) The projection display device according to (16), further including the polarizing beam splitter that transmits the light emitted from the light irradiation unit at least once and reflects the 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]
【The invention's effect】
As described above, according to the present invention, at least three kinds of wavelength selective reflection elements that reflect three kinds of wavelength bands, and a plurality of polarization plane rotation elements arranged on the light incident side of each of the wavelength selective reflection elements Are combined to form a color generation apparatus, a mechanical mechanism for rotating the color generation apparatus is not necessary, and the apparatus can be miniaturized.
[0090]
Further, according to the projection display device of the present invention, an image display that uses a reflective and stationary color generation element that sequentially outputs colors in different wavelength bands and generates a color image in conjunction with the change in the light. Since the light is reflected or transmitted through the body and further transmitted through the projection lens, the projection display device can be miniaturized.
[Brief description of the drawings]
FIG. 1A is a configuration diagram of a conventional projection display device, and FIG. 1B is a diagram showing a color generation device.
FIG. 2 is a block diagram of a basic color generation apparatus according to the first embodiment of the present invention.
FIG. 3 is a first exploded view of the color generation apparatus according to the first embodiment of the present invention.
FIG. 4 is a second exploded view of the color generation apparatus according to the first embodiment of the present invention.
FIG. 5 is a third exploded view of the color generation apparatus according to the first embodiment of the present invention.
FIG. 6 is a fourth exploded view of the color generation apparatus according to the first embodiment of the present invention.
FIG. 7 is a first voltage waveform diagram applied to the color generation apparatus 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 apparatus according to the first embodiment of the present invention.
FIG. 9 is a waveform diagram illustrating an output state of light colors having different polarization planes among light reflected from the color generation apparatus according to the first embodiment of the present invention.
FIG. 10 is a diagram showing the relationship between the alignment direction and arrangement of the liquid crystal panel constituting the color generation apparatus 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 constituting the color generation apparatus according to the first embodiment of the present invention.
FIG. 12 is a diagram showing a light polarization operation by the liquid crystal panel constituting the color generation apparatus of the first embodiment of the present invention.
FIG. 13 is a diagram illustrating a relationship between a voltage applied to a liquid crystal panel constituting the color generation apparatus according to the first embodiment of the present invention and a phase difference.
FIG. 14 is a second voltage waveform diagram applied to the color generation apparatus according to the first embodiment of the present invention.
FIG. 15 is a chart showing a relationship between voltages applied to a plurality of liquid crystal panels constituting the color generation apparatus 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 apparatus according to the first embodiment of the present invention.
FIG. 17 is a diagram showing a change in the color of the output of light that passes through the polarizer out of the light that is output according to the voltage waveform shown in FIG. 16;
FIG. 18 is a diagram illustrating an arrangement of a polarization beam splitter that polarizes an optical path of incident light and outgoing light of the color generation apparatus according to the first embodiment of the present invention, and the color generation apparatus.
FIG. 19 is a configuration diagram of an optical system of the projection display apparatus according to the first embodiment of the present invention.
FIG. 20 is a perspective view showing an arrangement of polarizers that combine linearly polarized light of incident light and color selection of emitted light in the projection display apparatus of the first embodiment of the present invention.
FIG. 21 is a chart showing the relationship between the voltage applied to the color generation device and the color that does not rotate the polarization when the polarizer shown in FIG. 20 is used.
FIG. 22 is a voltage waveform diagram applied to the color generation apparatus when the polarizer shown in FIG. 20 is used.
FIG. 23 is a first example of a waveform diagram of a voltage applied to a color generation device for monochrome display according to a second embodiment of the present invention.
FIG. 24 is a second example of a voltage waveform diagram applied to the color generation device for monochrome display according to the second embodiment of the present invention.
FIG. 25 is a diagram showing the orientation of liquid crystal molecules when a voltage is applied to a liquid crystal panel constituting a color generation apparatus according to a fourth embodiment of the present invention.
FIG. 26 (a) is a perspective view showing an elliptical polarization state of a liquid crystal panel constituting a color generation apparatus according to the fourth embodiment of the present invention, and FIG. 26 (b) corrects the elliptical polarization. It is the perspective view which has arrange | positioned the phase difference film on the one surface of the 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 constituting a color generation apparatus according to a fourth embodiment of the present invention.
FIG. 28 is a block diagram of a projection display apparatus according to a fifth embodiment of the present invention.
FIG. 29 is a block diagram showing a first example of a projection display apparatus according to a sixth embodiment of the present invention.
FIG. 30 is a block diagram showing a second example of the projection display apparatus according to the sixth embodiment of the present invention.
FIG. 31 is a block diagram showing a third example of the projection display apparatus according to the sixth embodiment of the present invention.
FIG. 32 is a block diagram showing a fourth example of the projection display apparatus according to the sixth embodiment of the present invention.
FIG. 33 is a block diagram showing a projection display apparatus according to a seventh embodiment of the present invention.
FIG. 34 is a block diagram showing a projection display apparatus according to an eighth embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 2, 3 ... Liquid crystal panel, 4r, 4b, 4g ... Dichroic mirror, 5, 6 ... Glass plate, 7 ... Polarizing beam splitter, 9 ... Retardation film, 10 ... Color generation apparatus (color generation element), 11 ... Light emitting source, 12 ... reflector, 13 ... polarizer, 14 ... projection lens, 15 ... display device, 16 ... polarizer, 17 ... aperture, 18 ... flat polarizing beam splitter, 19 ... polarization generating element.

Claims (3)

A first wavelength selective reflection element that reflects light in the first wavelength band, a second wavelength selective reflection element that reflects light in the second wavelength band, and a third wavelength band that are stacked in the light incident direction. A third wavelength selective reflection element that reflects
A first polarization plane rotation element disposed on the light incident side of the first wavelength selective reflection element, the phase difference of which varies by voltage control;
The second wavelength selective reflection element is disposed between the first wavelength selective reflection element and the second wavelength selective reflection element so that the orientation direction of the first polarization plane rotating element is inclined by 90 °, and the phase difference is changed by voltage control. A polarization plane rotation element of
The third wavelength-selective reflecting element is disposed between the second wavelength-selective reflecting element and the third wavelength-selective reflecting element so that the orientation direction of the second polarization plane rotating element is inclined by 90 °, and the phase difference is changed by voltage control. a polarization plane rotating element,
A polarizing element that is disposed on the light incident side and the light emitting side of the first polarization plane rotating element and extracts light of a specific polarization plane;
A first voltage at which a phase difference of light in the first wavelength band reflected by the first wavelength selective reflection element is λ / 4 (λ: wavelength in the first wavelength band); A second voltage at which a phase difference of the light in the second wavelength band reflected by the wavelength selective reflection element is λ / 4 (λ: a wavelength in the second wavelength band), the third wavelength selective reflection element A third voltage at which the phase difference of the light in the third wavelength band reflected by λ / 4 (λ; the wavelength in the third wavelength band) is set, and the first wavelength band, the second wavelength Either the wavelength band or the fourth voltage at which the phase difference between the lights in the third wavelength band is sufficiently eliminated is changed to the first polarization plane rotation element, the second polarization plane rotation element, and the first voltage. voltage control unit providing separately polarization plane rotating element 3 and have a <br/>,
The voltage controller applies the first voltage to the first polarization plane rotation element and the second polarization plane rotation element, and applies the fourth voltage to the third polarization plane rotation element. And applying the fourth voltage to the first polarization plane rotation element and applying the second voltage to the second polarization plane rotation element and the third polarization plane rotation element. And applying the fourth voltage to the first polarization plane rotation element and the second polarization plane rotation element, and applying the fourth voltage to the third polarization plane rotation element The first polarization plane rotation element, the second polarization plane rotation element, and the third polarization plane rotation element are selected by selecting any one of the third voltage application patterns for applying the third voltage. A color generating apparatus , wherein a voltage is applied to. The first polarization plane rotating element changes a phase difference of light in the first wavelength band by λ / 4 (λ: wavelength in the first wavelength band) when the first voltage is applied. ,
The second polarization plane rotation element changes a phase difference of light in the second wavelength band by λ / 4 (λ: wavelength in the second wavelength band) when the second voltage is applied. ,
The third polarization plane rotation element changes the phase difference of the light in the third wavelength band by λ / 4 (λ: wavelength in the third wavelength band) when the third voltage is applied. The color generation apparatus according to claim 1, wherein: Said first polarization plane rotation device, said second polarization plane rotation device, and said third polarization plane rotating element, according to claim 1 or claims nematic liquid crystal homogeneously aligned is characterized that you have been sealed Item 3. The color generation device according to Item 2.

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