JP2006293341A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a liquid crystal projection display device capable of performing bright image display of a wide color reproduction range with satisfactory light utilization efficiency. <P>SOLUTION: The image display device has a color separating means for separating incident light to three colored lights, three liquid crystal modulators for discretely modulating the polarization state of the respective colored lights, a polarization selecting means for transmitting or reflecting only the specific polarization and a color synthesizing means for synthesizing each colored light, and a projecting means for projecting the modulated image by the liquid crystal modulators based on the luminous flux passing through the color synthesizing means. The liquid crystal modulators perform TN mode operation by a nematic phase positive type. The three liquid crystal modulators consist of the same configuration and the amount of retardation application during no voltage application to the liquid crystal modulators corresponds to half the wavelength of roughly the central wavelength of the longest optical wavelength band among the three colored lights. The two liquid crystal modulators for modulating the remaining the two colored lights apply the retardation corresponding to half the wavelength of the roughly central wavelength of the optical wavelength band of each color light by the prescribed application of the voltage. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image display device, and in particular, generates a modulated image based on a polarization state of an image pattern by a liquid crystal modulation element, converts the image pattern into an intensity-modulated image by a polarization selection unit that selects the polarization state, and magnifies and projects the image pattern onto a projection object. This is particularly suitable.

  Conventionally, there is a liquid crystal modulation element in a two-dimensional pixel optical switch as an image modulation means used in a projection type image display apparatus, and a liquid crystal projector using this liquid crystal modulation element is known. A liquid crystal modulation element used for a liquid crystal projector includes, for example, a first transparent substrate having a transparent electrode, a second transparent substrate having a transparent electrode and wiring, a switching element and the like forming a pixel, and a dielectric anisotropy therebetween. There is known a so-called TN (Twisted Nematic) liquid crystal modulation element in which a positive nematic liquid crystal is sealed and a liquid crystal molecular long axis is continuously twisted by 90 ° between two transparent substrates.

  In addition to such a transmission type liquid crystal modulation element, a reflection type liquid crystal modulation element having a reflecting mirror built in one substrate is known as a two-dimensional pixel optical switch.

  The liquid crystal modulation element is used to form an image by controlling the polarization state using an ECB (Electrically Controlled Birefringence) effect. Of these, a liquid crystal modulation element of TN mode operation in which nematic liquid crystal having positive dielectric anisotropy is helically oriented and optically switched by birefringence of the liquid crystal is generally employed.

  When modulation is controlled by the ECB effect using this TN mode, liquid crystal molecules having different refractive indices in the major axis direction and the minor axis direction (minor axis direction) of the liquid crystal molecule are applied to the liquid crystal layer when no voltage is applied to the liquid crystal layer. Are arranged in a twist spiral of about 90 degrees in a plane substantially perpendicular to the layer thickness direction. For this reason, the liquid crystal layer has birefringence in a predetermined direction within the surface, and gives retardation (optical path length difference between two light beams having different polarization directions) to the light wave passing through the liquid crystal layer. It acts to change the polarization state of the wave.

  In general design of liquid crystal modulation elements, incident light is incident on a liquid crystal layer through a polarization control means such as a polarizer, and the polarization of the wave is changed to a linear polarization state in a predetermined direction, and the light is vibrated in this predetermined direction. When the linearly polarized light passing through the liquid crystal layer passes through the liquid crystal layer, a retardation of only a half wavelength is given at the incident light wavelength (the center of gravity wavelength of a certain light wavelength band).

  The light that has passed through the liquid crystal layer is emitted with the vibration direction changed to a direction perpendicular to the vibration direction of the linearly polarized light before entering the liquid crystal layer.

  After that, the polarization state is selected by arranging the polarization control means such as a polarizer having a crossed Nicol arrangement with the polarization control means arranged on the incident side on the emission side, and the selected light is transmitted through the polarization control means. It is composed.

  In contrast to this design, when a voltage is applied to the liquid crystal layer using the ECB effect, the liquid crystal molecules are tilted in the direction of the molecular major axis in the thickness direction of the liquid crystal layer, and the birefringence amount in the liquid crystal layer thickness direction is increased. Decrease. Then, the light wave that has passed through the liquid crystal layer becomes an elliptically polarized state in accordance with the voltage applied to the liquid crystal layer, and the light component whose vibration direction is not orthogonally converted is blocked by the polarization control means arranged on the light exit side. Thus, the intensity of incident light is modulated.

  The basic operation principle of this liquid crystal modulation element will be described with reference to FIGS.

  FIG. 5 is an operation explanatory diagram when a transmissive liquid crystal modulation element is used. In FIG. 5, light from a light source (not shown) passes through a polarization selection element composed of a polarizer (not shown) and the like. The linearly polarized light LIW forming an angle is incident on the transmissive liquid crystal modulation element 300.

At this time, the incident light LIW propagates through the liquid crystal layer of the transmissive liquid crystal modulation element 300 in two eigenmodes, and the emitted light LOW is a retardation δ expressed by the following equation (1) between the two eigenmodes. The light is emitted in the direction of the arrow OW in the figure with (λ).
δ (λ) = 2π (d · Δn) / λ (1)
In this case, λ is the wavelength of the incident light LIW, d is the thickness of the liquid crystal layer, and Δn is the refractive index anisotropy Δn of the liquid crystal layer.

  Next, the light LOW is passed through a polarization selection means 301 such as a polarizer that transmits linearly polarized light orthogonal to the polarization direction of the incident light LIW arranged on the exit side. In this case, the amount of light transmitted through the transmissive liquid crystal modulation element 300 and transmitted through the polarization selection unit 301, that is, the transmittance T (λ) of the transmissive liquid crystal modulation element 300 is as follows.

Assuming that the transmittance of the polarization selection means 301 is 100% with respect to the linearly polarized light to be transmitted, the aperture ratio of the transmissive liquid crystal modulation element 300 is 100%, and the non-polarized light transmittance is 100%, the phase difference δ (λ) In contrast, the light transmittance T (λ) of the light LMW that passes through the polarization selecting means 301 and is emitted in the direction of the arrow MW in the figure is T (λ) = 0.5 (1-cos (δ (λ))) ( 2)
It is represented by

  In the following, when the transmittance of the liquid crystal modulation element is referred to, the ratio of the amount of light passing through the polarization selection element 301 to the amount of linearly polarized light incident on the liquid crystal modulation element 300 through the polarization selection element as shown in the equation (2) is used. Say.

  When a voltage is applied to the liquid crystal layer, the liquid crystal molecules move from the horizontal to the vertical direction with respect to the sandwiched substrate of the liquid crystal layer, and as a result, the apparent refractive index anisotropy Δn decreases. Therefore, the retardation δ (λ) decreases, and when δ = 0, the transmittance T = 0 and black display is obtained.

  On the other hand, when no voltage is applied, the refractive index anisotropy Δn is maximum, and the liquid crystal layer thickness d and the refractive index anisotropy Δn of the liquid crystal layer are determined so that d · Δn = λ / 2. In this case, δ (λ) = π and the transmittance T = 1, and the maximum bright display is obtained.

  FIG. 6 is an operation explanatory diagram using a reflective liquid crystal modulation element. In FIG. 6, the light LIW from the light source enters the polarization beam splitter 401 from the direction of the arrow IW in the drawing, the P component light LIWB passes through the polarization selection film 401a in the direction of the arrow IWB in the drawing, and the S component light LIWA. Is reflected and deflected in the direction of arrow IWA in the figure. As the light component LIWA of the arrow IWA, light linearly polarized in the direction perpendicular to the paper surface is selected.

The liquid crystal alignment direction of the reflective liquid crystal modulation element 400 is inclined at 45 ° with respect to the linear polarization direction of the light LIWA. Light LIWA incident on the reflective liquid crystal modulation element 400 from the direction of the arrow IWA propagates in the liquid crystal layer of the reflective liquid crystal modulation element 400 in two eigenmodes. When the light is reflected and emitted in the direction of the arrow OW in the figure, the light LOW is emitted with the retardation δ (λ) expressed by the following equation (3) between the two modes.
δ (λ) = 2π (2d · Δn) / λ (3)
In this case, λ is the wavelength of incident light, d is the thickness of the liquid crystal layer, and Δn is the refractive index anisotropy Δn of the liquid crystal layer.

Therefore, the light LBW of the component perpendicular to the paper surface (S-polarized component with respect to the polarization beam splitter 401) of the light LOW emitted in the direction of the arrow OW in the figure is reflected in the direction of the arrow BW in the figure by the polarization separation surface 401a and returns to the light source side. The light LBW having a component parallel to the plane of the drawing (P-polarized component with respect to the polarization beam splitter 401) is transmitted in the direction of the arrow MW in the drawing by the polarization separation surface 401a. The amount of light reflected from the reflective liquid crystal modulation element 400 and transmitted through the polarization beam splitter 401, that is, the reflectance R (λ) of the reflective liquid crystal modulation element 400 is as follows. When the S-polarized light reflectance of the polarizing beam splitter 401 is 100%, the P-polarized light transmittance is 100%, the aperture ratio of the reflective liquid crystal modulation element 400 is 100%, and the non-polarized light reflectance is 100%, the retardation δ (λ) On the other hand, the reflectance (light transmission rate) R (λ) emitted in the direction of the arrow MW in the figure is R (λ) = 0.5 (1-cos (δ (λ))) (4)
It is represented by

  Here, the reflectance of the reflective liquid crystal display element is the amount of light passing through the polarization beam splitter 401 with respect to the amount of linearly polarized light incident on the liquid crystal modulation element 400 via the polarization beam splitter 401a as shown by the equation (4). The ratio of

  When a voltage is applied to the liquid crystal layer, the liquid crystal molecules move from the horizontal to the vertical direction with respect to the sandwiched substrate of the liquid crystal layer, and as a result, the apparent refractive index anisotropy Δn decreases. For this reason, the retardation δ (λ) decreases. When δ = 0, the transfer rate R = 0, and black is displayed.

  On the other hand, when no voltage is applied, the refractive index anisotropy Δn is maximum, and the liquid crystal layer thickness d and the refractive index anisotropy Δn of the liquid crystal layer are determined so that 2d · Δn = λ / 2. In this case, δ (λ) = π, the transfer rate R = 1, and the maximum bright display is obtained.

  The liquid crystal modulation element that performs modulation control using ECB effect control in the TN mode is based on the principle explained above, and as is clear from the fact that the phase difference δ is an amount dependent on the wavelength, There is a limitation on the amount of retardation that indicates the absolute amount of the retardation δ that does not depend on the light wavelength. In other words, the wavelength bands of incident light of the three primary colors are R, G, and B (red, green, and blue), and the wavelength band has a width of about 100 nm.

  Therefore, the TN type liquid crystal modulation element designed on the basis of a predetermined standard is configured to give a retardation of a half wavelength amount to light of a predetermined wavelength when no voltage is applied to the liquid crystal layer. For this reason, in a wavelength band of less than 100 nm corresponding to each color, a phenomenon in which more retardation than half wavelength is given depending on the wavelength or retardation less than half wavelength is inevitably generated.

  As another related limitation, since the TN mode is used, the amount of birefringence of the liquid crystal layer is maximized when no voltage is applied to the liquid crystal layer, and the amount of retardation applied is reduced by controlling the ECB effect. Although the direction can be controlled, it is impossible to increase the amount of retardation applied in the opposite direction.

  On the other hand, a full color display type projection display device (color projector) using a liquid crystal modulation element as a two-dimensional pixel optical switch is capable of performing additive color mixing display regardless of whether it is a transmission type liquid crystal modulation element or a reflection type liquid crystal modulation element. The mainstream is a configuration in which RGB (red, green, blue) color lights, which are primary colors, are individually modulated as a two-dimensional image and then a full-color image is displayed using a light combining means. In this color projector, three liquid crystal modulation elements that modulate light of each RGB color are used.

As a color projector using such three liquid crystal display elements, the one described in Patent Document 1 is known.
JP 2004-245977 A

  Therefore, in the present invention, the amount of retardation applied from the liquid crystal modulation element in the state in which no voltage is applied is not limited to RGB (not limited to the three colors RGB), and may of course be applied to a configuration in which four or more color lights are combined. It is an object of the present invention to provide an image display device that can prevent color balance from being lost, light intensity drop, and the like due to being different for each color.

  An image display device according to a first aspect of the present invention includes a TN-type first liquid crystal modulation element that modulates the polarization state of first color light, and TN that modulates the polarization state of second color light having a shorter wavelength than the first color light. Type liquid crystal modulation element, TN type third liquid crystal modulation element that modulates the polarization state of the third color light having a shorter wavelength than the second color light, and image light emitted from the three liquid crystal modulation elements An image display device including: an optical system configured to apply a first voltage to the first liquid crystal modulation element to give a half-wave phase difference to the first color light; A second voltage higher than the first voltage is applied to the second liquid crystal modulation element in order to give a half-wave phase difference, and the half-wave phase difference is given to the third color light. Applying a third voltage higher than the second voltage to the third liquid crystal modulation element. It is a symptom.

  The image display device according to the second aspect of the present invention modulates the polarization state of the TN-type first liquid crystal modulation element that modulates the polarization state of the first color light and the second color light having a shorter wavelength than the first color light. A TN-type second liquid crystal modulation element, a TN-type third liquid crystal modulation element that modulates the polarization state of the third color light having a shorter wavelength than the second color light, and image light emitted from the three liquid crystal modulation elements And an optical system for combining the first liquid crystal modulation element with respect to incident light in the absence of voltage applied to the incident light, rather than the retardation that the first liquid crystal modulation element provides to incident light with no voltage applied thereto. The retardation given to the incident light is smaller than the retardation that the second liquid crystal modulation element gives to the incident light when no voltage is applied to the incident light. Special It is set to.

  The image display device according to the third aspect of the present invention modulates the polarization state of the TN-type first liquid crystal modulation element that modulates the polarization state of the first color light and the second color light having a shorter wavelength than the first color light. A TN-type second liquid crystal modulation element, a TN-type third liquid crystal modulation element that modulates the polarization state of the third color light having a shorter wavelength than the second color light, and image light emitted from the three liquid crystal modulation elements And an optical system that combines the retardation of the first liquid crystal modulation element to the incident light when no voltage is applied and the second liquid crystal modulation element to the incident light when no voltage is applied. The retardation that is substantially the same as the retardation, and the retardation that the first and second liquid crystal modulation elements give to the incident light when no voltage is applied, is the retardation that the third liquid crystal modulation element gives to the incident light when no voltage is applied. Also large It is characterized in that.

  The image display device according to the fourth aspect of the present invention modulates the polarization state of the TN-type first liquid crystal modulation element that modulates the polarization state of the first color light and the second color light having a shorter wavelength than the first color light. A TN-type second liquid crystal modulation element, a TN-type third liquid crystal modulation element that modulates the polarization state of the third color light having a shorter wavelength than the second color light, and image light emitted from the three liquid crystal modulation elements The retardation of the first liquid crystal modulation element applied to the incident light when no voltage is applied is applied to the incident light when the second liquid crystal modulation element is applied with no voltage applied thereto. The retardation that the second liquid crystal modulation element gives to the incident light when no voltage is applied is substantially the same as the retardation that the third liquid crystal modulation element gives to the incident light when no voltage is applied. The It is a symptom.

  The image display device according to the fifth aspect of the present invention also modulates the TN-type first liquid crystal modulation element that modulates the polarization state of the first color light, and the polarization state of the second color light having a shorter wavelength than the first color light. A TN-type second liquid crystal modulation element, a TN-type third liquid crystal modulation element that modulates the polarization state of the third color light having a shorter wavelength than the second color light, and image light emitted from the three liquid crystal modulation elements And an optical system that synthesizes the three liquid crystal modulation elements in a state where the same voltage is applied to the three liquid crystal modulation elements, the three liquid crystal modulation elements have the same retardation with respect to light of the same wavelength. The amount of retardation applied when no voltage is applied to the three liquid crystal modulation elements corresponds to a half wavelength of a substantially central wavelength of the first color light, and the second and third liquid crystal modulations are configured. Each element is a liquid crystal modulation element By applying a voltage, is characterized in that by applying a retardation corresponding to a half wavelength of the approximate center wavelength of said second and third color light.

  The image display device according to the sixth aspect of the present invention also modulates a TN-type first liquid crystal modulation element that modulates the polarization state of the first color light and the polarization state of the second color light having a shorter wavelength than the first color light. A TN-type second liquid crystal modulation element, a TN-type third liquid crystal modulation element that modulates the polarization state of the third color light having a shorter wavelength than the second color light, and image light emitted from the three liquid crystal modulation elements The first and second liquid crystal modulation elements give the same first retardation to light of a certain wavelength in a state where a certain voltage is applied. The retardation applied to the light of the certain wavelength by the third liquid crystal modulation element in a state where the certain voltage is applied is different from the first retardation, and the first retardation is different from the first retardation. Liquid crystal modulation element The amount of retardation applied when no voltage is applied corresponds to the half wavelength of the approximate center wavelength of the first color light, and the amount of retardation applied when no voltage is applied to the third liquid crystal modulation element is approximately the center of the third color light. A voltage larger than 0 is applied to the second liquid crystal modulation element in order to provide a retardation corresponding to a half wavelength of the wavelength and corresponding to a half wavelength of a substantially central wavelength of the second color light. It is said.

  The image display device according to the seventh aspect of the present invention modulates the polarization state of the TN-type first liquid crystal modulation element for modulating the polarization state of the first color light and the second color light having a shorter wavelength than the first color light. A TN-type second liquid crystal modulation element, a TN-type third liquid crystal modulation element that modulates the polarization state of the third color light having a shorter wavelength than the second color light, and image light emitted from the three liquid crystal modulation elements The second and third liquid crystal modulation elements provide the same first retardation with respect to light of a certain wavelength in a state where a certain voltage is applied. The retardation applied to the light of the certain wavelength by the first liquid crystal modulation element in a state where the certain voltage is applied is different from the first retardation, and the first retardation is different from the first retardation. Liquid crystal modulation element The amount of retardation applied when no voltage is applied corresponds to a half wavelength of the approximate center wavelength of the first color light, and the amount of retardation applied when no voltage is applied to the second liquid crystal modulation element is approximately the center of the second color light. A voltage greater than 0 (zero) is applied to the third liquid crystal modulation element in order to provide a retardation corresponding to a half wavelength of the wavelength and corresponding to a half wavelength of a substantially central wavelength of the third color light. It is characterized by that.

  According to the present invention, it is possible to provide a liquid crystal display device capable of displaying an image having a better color balance and / or a brighter color than conventional ones.

  In the present embodiment, problems such as color balance disruption (light loss of a specific color) and light loss that may occur when the same liquid crystal modulation elements are used for RGB three colors, or color balance Solutions for reducing the degree of collapse, light loss, etc. are shown.

  Here, a conventional liquid crystal modulation element having the same configuration is used as a modulation element for each color light of RGB, and has the highest visibility characteristic (most visible to human eyes) in the vicinity of the center of gravity wavelength of the green color (G). When retardation of a half wavelength is given to the light wavelength, that is, when the retardation of all the liquid crystal modulation elements is set in accordance with the light having the highest visibility, there are the following problems. For example, an appropriate retardation amount (in this case, a half wavelength) can be imparted to G (green) light, but the retardation imparting amount of R (red) light is less than half a wavelength even when no voltage is applied. As a result, the light quantity of R (red) in the displayed image is reduced.

  Therefore, the following solutions can be considered. In an image display device (liquid crystal display device), a liquid crystal modulation element dedicated to each color is prepared as a liquid crystal modulation element for modulating each color of RGB, and the amount of retardation applied to each color light of each liquid crystal modulation element is appropriately set. It is a method. However, in this case, since the liquid crystal modulation elements having different specifications for each color of RGB must be manufactured, the manufacturing process becomes large.

  Therefore, in the present embodiment, the G (green) color liquid crystal display element is arranged in the G color light path and the B color light path. With this configuration, the voltage applied to the liquid crystal layer is adjusted for the liquid crystal modulation element arranged in the B color optical path (here, the voltage applied to the liquid crystal modulation element arranged in the G color optical path is adjusted). In addition, the brightness of the B (blue) color is adjusted by increasing the voltage applied to the liquid crystal modulation element disposed in the B-color optical path. If it does so, G light and B color can obtain appropriate light quantity. In addition, the liquid crystal modulation element arranged in the R color optical path is a liquid crystal modulation element different from the liquid crystal modulation elements arranged in common in the G color optical path and the B color optical path. That is, a liquid crystal modulation element in which the amount of retardation applied to the R color light is appropriately set, that is, in this case, the amount of retardation applied to the R color light (center of gravity wavelength) is half wavelength when no voltage is applied. By arranging in the optical path, the R color light in the color image can be set to an appropriate brightness.

  That is, in this embodiment, the same liquid crystal modulation elements are arranged in all the optical paths of the RGB color light, and the R color light is compared with the case where all the liquid crystal modulation elements are controlled in the same manner according to the center of gravity wavelength of the G color light. A liquid crystal display device capable of displaying an image with a small loss amount of (and / or B color light) will be specifically described.

  Hereinafter, drive control of the liquid crystal modulation element used in the liquid crystal display device of the present embodiment will be described with reference to FIGS.

  This embodiment uses a “nematic phase positive type TN (Twisted Nematic) mode liquid crystal modulation element”, and the refractive index in the major axis direction of the liquid crystal molecules is larger than the refractive index in the body diameter direction (rectangular direction). It is a large liquid crystal element. Here, the TN mode (or TN type) liquid crystal modulation element is configured to give a retardation of a half wavelength amount to light of a predetermined wavelength when no voltage is applied to the liquid crystal layer.

  FIG. 1 is a schematic diagram showing a state in which no voltage is applied to a liquid crystal layer using a TN mode of a transmissive liquid crystal modulator, and FIG. 2 is a predetermined voltage applied to the liquid crystal layer using a TN mode of a transmissive liquid crystal modulator. It is a schematic diagram which shows the state to which was applied.

  The transmissive liquid crystal modulation element includes a transparent substrate 101, a counter transparent substrate 102, and a liquid crystal layer 100a including liquid crystal molecules 100 sandwiched between these two substrates.

  A transparent pixel electrode 104 made of, for example, ITO (indium tin oxide), a liquid crystal alignment film 106 made of, for example, a polyimide polymer, and a pixel, arranged in a matrix in rows and columns (not shown) on the transparent substrate 101. A switching element 103 for electrically driving the electrode 104 and a wiring (not shown) are provided, and the pixel electrode 104 can be electrically driven individually.

  In addition, a transparent common electrode 105 made of, for example, ITO (indium tin oxide) and a liquid crystal alignment film 107 made of, for example, a polyimide-based polymer are formed on the opposing transparent substrate 102.

  Next, the operation of the transmissive liquid crystal modulation element will be described. In FIG. 1, light LIW from a light source is incident on an arrow direction IW in the figure as linearly polarized light whose polarization direction forms 45 ° with the alignment direction at the substrate interface of the liquid crystal molecules 100 through a polarization selection unit (not shown). Incident light LIW propagates and passes through the liquid crystal layer 100a in two eigenmodes and is emitted as light LOW in the direction of the arrow OW in the figure.

At this time, a retardation Δ expressed by the following equation is generated between the two modes in the liquid crystal layer 100a.
Δ = d · Δn (5)
In the formula (5), d is the thickness of the liquid crystal layer 100a, and Δn is the refractive index anisotropy of the liquid crystal layer.

Therefore, the transmittance T (λ) of the light component incident on the transmissive liquid crystal modulation element and orthogonal to the linearly polarized light of the incident light LIW is as follows. Assuming that the aperture ratio of the transmissive liquid crystal modulation element is 100% and the non-polarized light transmittance is 100%, the light transmittance T (λ) when emitted in the arrow OW direction with respect to the retardation Δ is T (λ) = 0. 5 (1-cos (2πΔ / λ)) (6)
It becomes.

  At this time, λ is the wavelength of the incident light.

  That is, the transmittance T (λ) depends on the wavelength λ of incident light with respect to the retardation Δ provided by the liquid crystal element itself. When retardation Δ is λ / 2, T (λ) = 1 is obtained, maximum transmission is obtained, and retardation Δ is maximum when no voltage is applied to the liquid crystal, that is, in the case of FIG. Δ cannot be increased.

  FIG. 2 shows a state (voltage application state) in which the electric field indicated by the dotted line arrow 108 is applied between the transparent electrodes 104 and 105 in the state of FIG.

  The liquid crystal molecules 100 are in a state of being slightly tilted displaced in the liquid crystal layer thickness direction by the applied electric field. The liquid crystal molecule 100 tilts the long axis direction having the refractive index anisotropy of the molecule in the light transmission direction, thereby reducing the apparent refractive index anisotropy Δn with respect to the light wave that is a transverse wave. Become.

  That is, the state of FIG. 2 shows a state in which the retardation Δ shown in the equation (5) is decreased by applying a voltage to the liquid crystal as compared with the state of FIG.

  On the other hand, the light spectrum for illuminating the liquid crystal modulation element by separating the three primary colors (RGB colors), for example, when an ultrahigh pressure mercury lamp is used as the light source, as shown in FIG. 7, is R color (solid line) and G color ( Broken line) and B color (dashed line).

  The center-of-gravity wavelength (center wavelength) of the wavelength band of each color is RC for R, GC for G, and BC for B.

  Here, the center-of-gravity wavelength λ 0 is the wavelength on the horizontal axis (wavelength) of the center of gravity of the area surrounded by the curve of the wavelength band of each color light in FIG. Alternatively, a representative wavelength of each color may be selected and used as the above-described center-of-gravity wavelength.

  In the state where no voltage is applied to the liquid crystal shown in FIG. 1, the wavelength of the center wavelength RC of the wavelength band of the R color which is the longest wavelength among the three primary colors is 1/2 wavelength (within a range of ± 5%). The liquid crystal modulation element is constituted by the refractive index anisotropy Δn of the liquid crystal layer 100a and the thickness d of the liquid crystal layer 100a so as to give the retardation ΔR = RC / 2 = d · Δn. In addition, the liquid crystal modulation element (liquid crystal panel) for R color modulation has a refractive index anisotropy Δn from a state where no voltage is applied (that is, a state where a retardation of approximately ½ wavelength is imparted to R color light). The R color light is modulated by adjusting the applied voltage for each pixel within a range up to a state where a voltage of almost zero is applied.

  As shown in FIG. 7, the liquid crystal panel for G color modulation is liquid crystal as long as the retardation Δ is ½ wavelength (within ± 5%) of the center of gravity wavelength GC of the G color wavelength band. By adjusting the applied voltage for each pixel within the range from the state where the voltage is applied (applied voltage EG) to the state where the voltage where the refractive index anisotropy Δn is almost zero is applied (applied voltage EGO), Modulates color light.

  Further, in the liquid crystal panel for B color modulation, a voltage is applied to the liquid crystal so that the retardation Δ is 1/2 wavelength (within ± 5% of range) with respect to the center of gravity wavelength BC of the B color wavelength band. The B color light is modulated by adjusting the applied voltage for each pixel within a range from (applied voltage EB) to a state in which a voltage at which the refractive index anisotropy Δn is substantially 0 is applied (applied voltage EBO). .

  With this configuration, the transmittance of the R color, which is the longest wavelength band, is not lost (the light amount of the R color in the displayed image is not lost, or the R color in the displayed image is not lost). While preventing the color balance from being lost due to a decrease in the amount of light, or reducing the light amount of the R color in the displayed image, reducing the amount of light loss and the color balance based on it, improving the light utilization efficiency be able to. In addition, in order to adjust the color balance (to balance the amount of light for each color), it is possible to prevent deterioration of color purity by shifting the wavelength band of the R color to the G side (or to the G side). Yes.

  In this embodiment, since the maximum retardation amount Δmax of the liquid crystal modulation element is set to the center wavelength of the R color (within a range of ± 5%), the modulation of all colors of R, G, and B is performed. Not only when the same liquid crystal modulation element is used, but the liquid crystal modulation element having the same configuration is used for the modulation of the R and G colors, and the liquid crystal arranged in the optical paths of the R and G color lights in the modulation of the B color. An organized liquid crystal modulation element different from the modulation element may be used. Specifically, a phase difference corresponding to a half wavelength is given to the centroid wavelength of B color in a substantially no voltage applied state, and no phase difference is given to the centroid wavelength of B color from that state, that is, the liquid crystal You may use the liquid crystal modulation element which can change an applied voltage until the refractive index anisotropy (DELTA) n with respect to the gravity center wavelength of B color of a modulation element becomes substantially zero.

  In this case, in order to suppress light resistance deterioration due to short wavelength light with high photon energy, it is possible to use only liquid crystal modulation elements for B color light modulation using liquid crystals with high light resistance or various polymer materials. There is an advantage of becoming.

  In addition, a liquid crystal modulation element having the same configuration may be used for the modulation of the G color and the B color, and a liquid crystal modulation element having a configuration different from the liquid crystal modulation element may be used for the modulation of the R color. . In this case, the amount of retardation applied to the liquid crystal modulation element for R color without applying voltage is set to ½ wavelength of the center of gravity wavelength RC of the R color light, and G for the liquid crystal modulation element for G color with no voltage applied. The amount of retardation applied to the barycentric wavelength GC of the color light is set to ½ wavelength of the barycentric wavelength GC. In this case, since the liquid crystal modulation element is in a state in which no voltage is applied and does not give a phase difference corresponding to ½ wavelength of the centroid wavelength BC to the centroid wavelength BC of the B color light, the optical path of the B color light If the liquid crystal modulation element common to the G color and the B color disposed inside is controlled so that the amount of retardation applied in a state where a predetermined voltage is applied is ½ wavelength of the barycentric wavelength BC of the B color good.

  Next, a reflective liquid crystal modulation element will be described.

  FIG. 3 is a schematic diagram showing a state in which no voltage is applied to the liquid crystal layer using the TN mode of the reflective liquid crystal modulation element, and FIG. 4 is a diagram illustrating a case where a predetermined voltage is applied to the liquid crystal layer using the TN mode of the reflective liquid crystal modulation element. It is a schematic diagram which shows the state applied.

  The reflective liquid crystal modulation element has a silicon substrate 201, a counter transparent substrate 202, and a liquid crystal layer 200a including liquid crystal molecules 200 sandwiched between the two substrates.

  The silicon substrate 201 has a mirror pixel electrode 204 made of aluminum and arranged in a matrix in rows and columns (not shown), a liquid crystal alignment film 206 made of, for example, a polyimide polymer, and the mirror pixel electrode 204. And a switching circuit layer 203 including a switching element made of a MOSFET or the like for electrically driving the mirror pixel electrode 204, and the mirror pixel electrode 204 can be electrically driven individually.

  Further, a transparent common electrode 205 made of, for example, ITO (indium tin oxide) and a liquid crystal alignment film 207 made of, for example, a polyimide-based polymer are formed on the counter transparent substrate 202 (liquid crystal layer side).

Next, the operation of the reflective liquid crystal modulation element will be described. In FIG. 3, light LIW from the light source is incident in the direction of arrow IW in the figure as linearly polarized light whose polarization direction forms 45 ° with the alignment direction at the substrate interface of the liquid crystal molecules 100 through a polarization selection unit (not shown). Incident light LIW is propagated and reflected through the liquid crystal layer 200a in two eigenmodes, and is emitted as light LOW in the direction of the arrow OW in the figure. At this time, a retardation Δ represented by the following equation is generated between the two modes in the liquid crystal layer 200a.
Δ = 2d · Δn (7)
In the formula (7), d is the thickness of the liquid crystal layer, and Δn is the refractive index anisotropy of the liquid crystal layer 200a. Therefore, the reflectance R (λ) of light of the component orthogonal to the linearly polarized light of the incident light LIW out of the light that is reflected back and forth from the reflective liquid crystal modulation element by the mirror pixel electrode 204 is as follows.

Assuming that the aperture ratio of the reflective liquid crystal modulation element is 100% and the non-polarization reflectance is 100%, the light reflectance R (λ) emitted in the arrow OW direction with respect to the retardation Δ is R (λ) = 0.5 ( 1-cos (2πΔ / λ)) (8)
It becomes.

  At this time, λ is the wavelength of the incident light. That is, as in the case of the transmissive liquid crystal, the reflectance R (λ) depends on the incident light wavelength λ with respect to the retardation Δ provided by the liquid crystal element itself. When the retardation Δ is λ / 2, R (λ) = 1 and maximum reflection is obtained, and the retardation Δ is maximum when no voltage is applied to the liquid crystal, that is, in the case of FIG. 3, and the retardation Δ is larger than this state. It cannot be increased.

  4 shows a state (voltage application state) in which the electric field indicated by the dotted arrow 208 in the drawing is applied between the transparent electrodes 204 and 205 in the state of FIG.

  The liquid crystal molecules 200 are in a state of being slightly tilted displaced in the liquid crystal layer thickness direction by the applied electric field. The liquid crystal molecule 200 tilts the major axis direction having the refractive index anisotropy of the molecule in the light reflection direction, thereby reducing the apparent refractive index anisotropy Δn with respect to the light wave that is a transverse wave. Become. That is, the state of FIG. 4 shows a state in which the retardation Δ shown in the equation (7) is decreased by applying a voltage to the liquid crystal as compared with the state of FIG.

  Therefore, in the state where no voltage is applied to the liquid crystal shown in FIG. 3, the retardation ΔR corresponding to ½ wavelength with respect to the wavelength of the center wavelength RC of the red color wavelength band which is the longest wavelength among the three primary colors. A liquid crystal modulation element is constituted by the refractive index anisotropy Δn of the liquid crystal layer 200a and the thickness d of the liquid crystal layer 200a so as to give = RC / 2 = d · Δn.

  The liquid crystal panel for red color modulation is subjected to reflection modulation in a range in which a voltage at which the refractive index anisotropy Δn is almost 0 is applied from a state where no voltage is applied. As shown in FIG. 4, the liquid crystal panel for G color modulation has a refractive index difference from a state in which a voltage is applied to the liquid crystal so that the retardation Δ is ½ wavelength with respect to the center wavelength GC of the G color wavelength band. Reflection modulation is performed within a range in which a voltage at which the directivity Δn becomes approximately 0 is applied.

  Further, in the liquid crystal panel for B color modulation, the refractive index anisotropy Δn is almost from the state in which the voltage is applied to the liquid crystal so that the retardation Δ is ½ wavelength with respect to the center wavelength BC of the B color wavelength band. Reflection modulation is performed within a range in which a voltage of 0 is applied. As a result, the color purity by shifting the wavelength band of the R color to the G side in order to improve the light use efficiency without losing the reflectance of the R color, which is the longest wavelength band, and to adjust the color balance. It is possible to prevent the deterioration of.

  Similarly to the transmissive liquid crystal example, the present embodiment sets the maximum retardation amount Δmax of the liquid crystal modulation element to the center of gravity wavelength of the red color, so that all colors of R, G, and B can be modulated. On the other hand, not only when the same liquid crystal modulation element is used, but also when the same liquid crystal modulation element is used for the modulation of R and G colors.

  In this case, in order to suppress light resistance deterioration due to short-wavelength light with high photon energy, it is possible to use a liquid crystal modulation element for B-color light modulation exclusively as a liquid crystal with high light resistance or various polymer materials. There is an advantage of becoming.

  As described above, the liquid crystal modulation element in this embodiment is a nematic phase positive type TN mode operation modulation element, and the three liquid crystal modulation elements have the same structure, and when no voltage is applied to the liquid crystal modulation element. The amount of retardation applied corresponds to the half wavelength of the center wavelength of the longest light wavelength band among the three color lights, and the two liquid crystal modulation elements that modulate the remaining two color lights are approximately the center of the light wavelength band of each color light. Retardation corresponding to half the wavelength is applied by applying a predetermined voltage.

  Here, when the three liquid crystal modulation elements have the same structure, specifically, it can be said that the configuration is as follows. For example, a first liquid crystal modulation element that modulates the polarization state of the first color light (R color), and a second liquid crystal modulation element that modulates the polarization state of the second color light (G color) having a shorter wavelength than the first color light. And a third liquid crystal modulation element that modulates the polarization state of the third color light (B color) having a wavelength shorter than that of the second color light, and an image that is displayed by synthesizing image light from the three liquid crystal modulation elements In the display device, the three liquid crystal modulation elements are TN type liquid crystal modulation elements, and a first voltage is applied to the first liquid crystal modulation element in order to give a half-wave retardation to the first color light, A second voltage higher than the first voltage is applied to the second liquid crystal modulation element in order to give half-wave retardation to the second color light, and half-wave retardation is given to the third color light. A third higher than the second voltage to Applying a pressure to the third liquid crystal modulation element. In the image display device having the same configuration, the three liquid crystal modulation elements are TN liquid crystal modulation elements, and the first liquid crystal modulation element gives incident light (for example, to the first color light) in a state where no voltage is applied. The retardation that the second liquid crystal modulation element gives to the incident light (for example, to the first color light) in a state where no voltage is applied is smaller than the retardation, and the second liquid crystal modulation element does not change the incident light (for example, in the state where no voltage is applied). The retardation that the third liquid crystal modulation element gives to the incident light (for example, to the first color light) may be configured to be smaller than the retardation given to the first color light.

  In addition, the three liquid crystal modulation elements in this embodiment include two liquid crystal modulation elements B, G, and R when the liquid crystal modulation elements that perform light modulation in the order of the shortest wavelength among the three color lights that are light modulated. The modulation elements G and R have the same structure, the liquid crystal modulation element B has a different structure from the other two liquid crystal modulation elements G and R, and the amount of retardation applied to the liquid crystal modulation element B when no voltage is applied is 3 This corresponds to the half wavelength of the center wavelength of the shortest light wavelength band of the two color lights, and the retardation applied amount when no voltage is applied to the liquid crystal modulation element R is the light wavelength band of the color of the longest wavelength of the three color lights. The liquid crystal modulation element G, which corresponds to a half wavelength of a substantially central wavelength, imparts a retardation corresponding to a half wavelength of a substantially central wavelength in the wavelength band of intermediate color light by applying a predetermined voltage.

  In this way, when the G and R liquid crystal modulation elements have the same structure and the B liquid crystal modulation element has a different structure, it can be said that the structure is as follows. For example, a first liquid crystal modulation element that modulates the polarization state of the first color light, a second liquid crystal modulation element that modulates the polarization state of the second color light having a shorter wavelength than the first color light, and a wavelength longer than the second color light. And a third liquid crystal modulation element that modulates the polarization state of the short third color light, and the three liquid crystal modulation elements are TN. A retardation that the first liquid crystal modulation element gives to incident light (for example, to the first color light) in a state where no voltage is applied; For example, the retardation given to the first color light is substantially the same, and the retardation given to the incident light (for example, to the first color light) by the first and second liquid crystal modulation elements without applying a voltage is the third liquid crystal. Modulator element has no voltage Greater than the retardation applied to the incident light pressure state (e.g., the first color light).

  In addition, the two liquid crystal modulation elements G and B in this embodiment have the same structure, the liquid crystal modulation element R has a structure different from the other two liquid crystal modulation elements G and B, and no voltage is applied to the liquid crystal modulation element R. The amount of retardation applied when applied corresponds to the half wavelength of the approximate center wavelength of the longest light wavelength band among the three colored lights, and the amount of retardation applied when no voltage is applied to the liquid crystal modulation element G is the middle of the three colored lights. The liquid crystal modulation element B corresponds to a half wavelength of the center wavelength of the shortest color light by applying a predetermined voltage to the liquid crystal modulation element B. Yes.

  In this way, when the liquid crystal modulation elements for B and G have the same structure and the liquid crystal modulation element for R has a different structure, it can be said that the structure is as follows. For example, a first liquid crystal modulation element that modulates the polarization state of the first color light, a second liquid crystal modulation element that modulates the polarization state of the second color light having a shorter wavelength than the first color light, and a wavelength longer than the second color light. And a third liquid crystal modulation element that modulates the polarization state of the short third color light, and the three liquid crystal modulation elements are TN. The retardation that the first liquid crystal modulation element gives to the incident light (for example, to the first color light) when no voltage is applied to the incident light when the second liquid crystal modulation element is applied with no voltage ( For example, the retardation applied to the incident light (for example, to the first color light) in a state in which no voltage is applied to the second liquid crystal modulation element and the third liquid crystal modulation element in the state in which no voltage is applied. Incident light For example, the first color light) and the retardation providing are substantially the same.

  The “same structure” as used herein refers to substantially the same retardation (phase difference) for light of the same wavelength when no voltage is applied, and the same wavelength when a predetermined voltage is applied. This means that substantially the same retardation is given. In other words, even if the appearance is slightly different, it is possible that they have the same structure.

  This embodiment is not limited to the above. For example, all the liquid crystal modulation elements R, G, and B may have different structures. That is, each liquid crystal modulation element is configured to give different retardation (optical path length difference) to incident light (which may be light of any wavelength, but is preferably in the visible light region). It doesn't matter. Specifically, the retardation (optical path length difference) given to the incident light (light having any wavelength, but preferably in the visible region) by the liquid crystal modulation element R in a state where no voltage is applied, The retardation applied to the incident light by the liquid crystal modulation element G when no voltage is applied is greater than the retardation provided by the liquid crystal modulation element B when no voltage is applied to the incident light. It is configured to be larger. Here, the retardation means an optical path length difference between two lights whose polarization directions are orthogonal to each other. Even if the optical path length difference is the same (the structure is the same), the optical path length is the same. If the wavelength of the given light is different, the resulting phase difference is different.

  In this case, the phase difference given to the R color light (the representative wavelength of R color light or the R color light wavelength region) when the liquid crystal modulation element R is not applied with voltage, and the G color light when the liquid crystal modulation element G is not applied with voltage. A phase difference given to (a representative wavelength of G color light or a G color light wavelength region) and a liquid crystal modulation element B to B color light (a representative wavelength of B color light or a B color light wavelength region) in a state where no voltage is applied. It is desirable that the phase difference is substantially the same (one is 95% or more and 105% or less, preferably 98% or more and 102% or less), and the phase difference is substantially a half wavelength. However, when actually giving a half-wave phase difference to each color light, a minute amount of voltage may be applied to each liquid crystal modulation element.

  Note that the retardation is substantially the same, one means 95% or more and 105% or less, preferably 98% or more and 102% or less of the other.

  As described above, the characteristics of the configuration of the image display apparatus according to the present embodiment are as follows.

A first liquid crystal modulation element for modulating the polarization state of the first color light;
A second liquid crystal modulation element that modulates the polarization state of the second color light having a shorter wavelength than the first color light;
A third liquid crystal modulation element that modulates the polarization state of the third color light having a wavelength shorter than that of the second color light, and combines and displays the image light from the three liquid crystal modulation elements.

At this time, the three liquid crystal modulation elements are TN liquid crystal modulation elements.
And a first voltage is applied to the first liquid crystal modulation element in order to give a half-wave retardation to the first color light (a retardation corresponding to the half-wavelength of the first color light). A second voltage higher than the first voltage is applied to the second liquid crystal modulation element to provide half-wave retardation (retardation corresponding to the half-wavelength of the second color light), and half wavelength relative to the third color light. Applying a third voltage higher than the second voltage to the third liquid crystal modulation element in order to provide retardation (a retardation corresponding to a half wavelength of the third color light);
Rather than the retardation that the first liquid crystal modulation element gives to incident light (for example, to the first color light) when no voltage is applied, the retardation that the second liquid crystal modulation element gives to incident light (for example, to the first color light) when no voltage is applied. Is smaller than the retardation that the second liquid crystal modulation element gives to incident light (for example, to the first color light) when no voltage is applied to the incident light (for example, the first liquid crystal modulation element). The retardation given to the colored light is smaller. ◎ The retardation given to the incident light (for example, to the first color light) when the first liquid crystal modulation element is not applied with voltage, and the incident light when the second liquid crystal modulation element is not applied with voltage. The retardation to be given (for example to the first color light) is substantially the same,
Retardation that the first and second liquid crystal modulation elements give to incident light (for example, to the first color light) in a state where no voltage is applied, and retardation that the third liquid crystal modulation element gives to incident light (for example, to the first color light) when no voltage is applied. The retardation that the first liquid crystal modulation element gives to the incident light (for example, to the first color light) in the state where no voltage is applied is applied to the incident light (for example, the first color light, for example). ) Larger than the applied retardation, the retardation applied to the incident light (for example, to the first color light) by the second liquid crystal modulation element in the absence of voltage application, and the incident light (for example, the first liquid crystal modulation element in the absence of voltage application). The retardation applied to the color light is substantially the same. A first voltage is applied to the first liquid crystal modulation element in order to give a half-wave retardation to the first color light. A second voltage higher than the first voltage is applied to the second liquid crystal modulation element in order to give half-wave retardation to the light, and a second voltage is given to give half-wave retardation to the third color light. It is characterized in that a higher third voltage is applied to the third liquid crystal modulation element.

  This facilitates the achievement of a liquid crystal projection type image display device capable of displaying a bright image with a wide color reproduction range.

  Next, Example 1 of the projection display apparatus of this example will be described with reference to FIG. FIG. 8 is a cross-sectional view of main optical systems constituting the first embodiment of the projection display apparatus.

  In FIG. 8, a red light modulation panel comprising a transmission type liquid crystal modulation element as a drive signal from a light modulation panel driver 3 for converting an external video input signal (not shown) into a light modulation panel drive signal through a solid line in the figure. The 2R, green light modulation panel 2G and blue light modulation panel 2B are independently controlled.

  At this time, the voltage applied to each light modulation panel 2R, 2G, 2B is controlled as described above.

  On the other hand, the illumination light that is linearly polarized and polarized in the direction perpendicular to the paper surface from the illumination means 1 (the side view is written horizontally) reflects red and transmits cyan (green and blue). First, the red color component R is deflected by the dichroic mirror 20 for wavelength band separation, and the deflected red color R is guided to the red light modulation panel 2R by the total reflection mirror 22. On the other hand, the cyan component transmitted and separated by the dichroic mirror 20 for red / cyan wavelength band separation reflects the yellow color, and the cyan yellow component is reflected by the yellow / blue wavelength band separation dichroic mirror 21 that transmits the blue color B. The green color component is deflected, and the deflected green color G is guided to the green light modulation panel 2G. Then, the blue color B component transmitted and separated by the dichroic mirror 21 for separating the yellow-blue wavelength band is guided to the blue light modulation panel 2B by the total reflection mirrors 23 and 24. At this time, in order to extend the optical path length, the pupil is transferred to the light modulation panel 2B by the cat's eye optical system using the Fourier transform lenses 25 and 26.

  Each of the red light modulation panels 2R, the green light modulation panel 2G, and the blue light modulation panel 2G is illuminated with the above-described illumination configuration.

  On the other hand, the illumination light linearly polarized in the direction perpendicular to the paper surface by the red light modulation panel 2R, the green light modulation panel 2G, and the blue light modulation panel 2G modulated in accordance with the video signal is converted into each red light. Polarization retardation is given according to the modulation state of the pixels arranged in the modulation panel 2R, the green light modulation panel 2G, and the blue light modulation panel 2G.

  The light beam, which is affixed to the light incident surface of each color of the cross dichroic prism 12 and modulated by the light modulation panel 2R for red, is a red analyzer (analyzer is light having a polarization state different from that of image light). An optical element that shields light from the projection optical system, and may be, for example, a polarizing plate or a polarizing beam splitter.) 27, the light beam modulated by the green light modulation panel 2G is the green analyzer 28, blue light. The light beam modulated by the light modulation panel 2B transmits the modulated light component polarized and polarized in the direction perpendicular to the paper surface by the blue analyzer 29, and the modulated light component polarized and polarized in the horizontal direction on the paper surface is absorbed by the analyzer. Dissipates as heat. Thereafter, the modulated light component polarized and polarized in the direction perpendicular to the plane of the paper subjected to the modulation of each color enters the cross dichroic prism 12.

  The cross dichroic prism 12 reflects the red color R and reflects the red color dichroic wavelength band separation film 12R that reflects the red color R and transmits the green color G and the blue color B, and reflects the blue color B and the green color G. The blue reflection dichroic wavelength band separation film 12B that transmits the red color R is configured in a cross-like shape.

  Accordingly, green has a characteristic of mainly transmitting through the red reflecting dichroic wavelength band separating film 12R and the blue reflecting dichroic wavelength band separating film 12B. By using the cross dichroic prism 12, the red color R image information light is deflected in the direction of the projection lens 4 by the red reflecting dichroic wavelength band separation film 12R, and the blue color B image information light is reflected by the blue reflecting dichroic wavelength. The band separation film 12B is deflected in the direction of the projection lens 4, and the image information light emission of green color G proceeds in the direction of the projection lens 4 without being subjected to the deflection action.

  However, a plurality of arranged pixels in each of the red light modulation panel 2R, the green light modulation panel 2G, and the blue light modulation panel 2G are adjusted or mechanically adjusted such that the predetermined pixels overlap with a predetermined accuracy. Electrically compensated.

  Next, the light R, G, B modulated as a combined color is captured by the entrance pupil of the projection lens 4 as it is, and each of the red light modulation panel 2R, the green light modulation panel 2G, and the blue light modulation. Since the light modulation surface of the panel 2G and the light diffusion surface of the light diffusion screen 5 are arranged in an optical conjugate relationship by the projection lens 4, the image is transferred to the light diffusion screen 5 and the image based on the video signal is light diffusion. It is displayed on the screen 5.

  Example 2 of the projection display apparatus of this example will be described with reference to FIG. FIG. 9 is a cross-sectional view of the main optical system constituting the embodiment 2 of the projection display apparatus.

  In FIG. 9, a red light modulation panel comprising a reflection type liquid crystal modulation element as a drive signal from a light modulation panel driver 3 for converting an external video input signal (not shown) into a light modulation panel drive signal via a solid line in the figure. 2R, the green light modulation panel 2G, and the blue light modulation panel 2G are independently controlled. On the other hand, the illumination light linearly polarized in the direction perpendicular to the paper surface from the illumination means 1 (side view is shown horizontally) is applied. The magenta green wavelength band separation dichroic mirror 30 reflects the magenta color (red color and blue color) and transmits the green color G. The magenta color component is first deflected, and the deflected magenta color is half-wave converted to the blue polarized light. The blue color component B that passes through the blue cross-color polarizer 34 that gives the retardation of the light and is linearly polarized in the horizontal direction of the paper, and the vertical of the paper A red color component that is linearly polarized in the direction is created, and then the blue color component B that is incident on the polarization beam splitter 33 and linearly polarized in the horizontal direction in the drawing is transmitted through the polarization separation film 33a as a P polarized wave. Then, the red color component R, which is guided to the blue light modulation panel 2B and linearly polarized in the direction perpendicular to the paper surface, is reflected by the polarization separation film 33a due to the S-polarized wave and is guided to the red light modulation panel 2R. .

  On the other hand, the green color component G transmitted and separated by the magenta green wavelength band separation dichroic mirror 30 passes through the dummy glass 36 for correcting the optical path length, and then enters the polarization beam splitter 31 in the direction perpendicular to the paper surface. The linearly polarized polarized green color component G is reflected by the polarization splitting film 31a as an S-polarized wave and guided to the green light modulation panel 2G.

  Each of the red light modulation panels 2R, the green light modulation panel 2G, and the blue light modulation panel 2G is illuminated with the above-described illumination configuration.

  On the other hand, the red light modulation panel 2R, the green light modulation panel 2G, and the blue light modulation panel 2G modulated according to the video signal are used to illuminate the light modulation panels 2R, 2G, and 2B. Polarization retardation is given according to the modulation state of the pixels arranged in the light modulation panel 2R for green, the light modulation panel 2G for green, and the light modulation panel 2G for blue.

  The polarization polarization component in the same direction as the illumination light returns to the light source lamp side by following the optical path that substantially pulls back the illumination optical path, and for the polarization polarization component perpendicular to the polarization direction of the illumination light, the red light modulation The modulated light from the panel 2R has a polarization polarization direction that is horizontal to the paper surface, passes through the polarization separation film 33a of the polarization beam splitter 33 for the P-polarized wave, and then gives red half-wave retardation to the red polarized light. It passes through the cross-color polarizer 35 and is converted into a red color component R that is linearly polarized and polarized in the direction perpendicular to the paper surface. Then, the red color component that is incident on the polarization beam splitter 32 and linearly polarized and polarized in the direction perpendicular to the paper surface. Reflects the polarized light separation film 32 a due to the S-polarized wave and is deflected in the direction of the projection lens 4.

  The light modulated by the blue light modulation panel 2B is polarized in the direction perpendicular to the plane of the drawing, reflected by the polarization separation film 33a of the polarization beam splitter 33 due to the S-polarized wave, and then converted into the red R polarization by half wavelength. The blue color component B that passes through the red cross color polarizer 35 that gives the retardation of the light beam without being affected, and then enters the polarization beam splitter 32 and linearly polarized in the direction perpendicular to the paper surface, passes through the polarization separation film 32a. Reflected by the S-polarized wave and deflected in the direction of the projection lens 4.

  The modulated light from the green light modulation panel 2G has the polarization polarization direction horizontal to the paper surface, passes through the polarization separation film 32a of the polarization beam splitter 31 for the P-polarized wave, and then dummy for correcting the optical path length. The green color component G that has passed through the glass 37 and then entered the polarization beam splitter 32 and linearly polarized and polarized in the horizontal direction on the paper surface is transmitted through the polarization separation film 32a as a P-polarized wave, and the direction of the projection lens 4 Led to. However, a plurality of arranged pixels in each of the red light modulation panel 2R, the green light modulation panel 2G, and the blue light modulation panel 2G are adjusted or mechanically adjusted such that the predetermined pixels overlap with a predetermined accuracy. Electrically compensated.

  Next, the light R, G, B modulated as a combined color is captured by the entrance pupil of the projection lens 4 as it is, and each of the red light modulation panel 2R, the green light modulation panel 2G, and the blue light modulation. Since the light modulation surface of the panel 2G and the light diffusion surface of the light diffusion screen 5 are arranged in an optical conjugate relationship by the projection lens 4, the image is transferred to the light diffusion screen 5 and the image based on the video signal is light diffusion. It is displayed on the screen 5.

  As described above, according to each embodiment, the liquid crystal modulation elements (modulation liquid crystal panels) for the three primary colors are not red light components or green light having the longest light wavelength without using individual products having different shapes. A liquid crystal projection display device that is bright and has a wide color reproduction range can be provided by a simple method without losing the use efficiency of colored light.

In the above-described embodiments, the liquid crystal modulation element that imparts a retardation of approximately half wavelength in a state where no voltage is applied has been described. However, the present invention is not limited thereto. For example, a liquid crystal modulation element having a configuration in which retardation is not substantially applied in a state where no voltage is applied, and the retardation is applied to incident light only after voltage is applied may be used. In that case, in a liquid crystal display device (liquid crystal projector) using a transmissive liquid crystal modulation element, the polarization direction aligned with the liquid crystal modulation element (the polarization direction transmitting through the polarizing plate on the incident side of the liquid crystal modulation element) and If the direction of polarization transmitted through the polarizing plate on the output side of the liquid crystal modulation element is parallel, white display is obtained when no voltage is applied. Conversely, in the case of a transmissive liquid crystal projector, the polarization on the incident side of the liquid crystal modulation element If the polarization direction that transmits through the plate and the polarization direction that transmits through the polarizing plate on the exit side of the liquid crystal modulation element are perpendicular, black display is obtained when no voltage is applied. Further, in a liquid crystal display device (liquid crystal projector) using a reflective liquid crystal modulation element, when a polarization beam splitter is disposed at a position facing the liquid crystal modulation element, black display is performed when no voltage is applied. However, even in such a case, white display can be performed in a state where no voltage is applied, by appropriately arranging a quarter-wave plate between the reflective liquid crystal modulation element and the polarizing beam splitter.

  According to the present embodiment, it is possible to provide an image device capable of displaying an image having a better color balance and / or a brighter color than conventional ones.

Schematic for explaining a driving state of a transmission type liquid crystal modulation element according to an embodiment of the present embodiment Schematic for explaining a driving state of a transmission type liquid crystal modulation element according to an embodiment of the present embodiment Schematic for explaining the drive state of the reflective liquid crystal modulation element according to the embodiment of the present embodiment Schematic for explaining the drive state of the reflective liquid crystal modulation element according to the embodiment of the present embodiment Schematic for explaining the operation of a transmissive liquid crystal modulation element Schematic for explaining the operation of the reflective liquid crystal modulation element Diagram showing wavelength distribution of light incident on liquid crystal modulator Schematic diagram of a main part of a projection display device using a transmission type liquid crystal modulation element according to an embodiment of the present embodiment. Schematic of the main part of a projection display device using a reflective liquid crystal modulation element according to an embodiment of the present embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Illumination means 2R Red light modulation panel 2G Green light modulation panel 2B Blue light modulation panel 3 Light modulation panel driver 4 Projection lens 5 Light diffusion screen 12 Cross dichroic prism 20 Red cyan wavelength band separation dichroic mirror 21 Yellow blue wavelength band Separation dichroic mirror 22 Total reflection mirror 23 Total reflection mirror 24 Total reflection mirror 25 Fourier transform lens 26 Fourier transform lens 27 Red analyzer 28 Green analyzer 29 Blue analyzer 30 Magenta green wavelength band separation dichroic mirror 31 Polarizing beam splitter 32 Polarizing beam splitter 33 Polarizing beam splitter 34 Blue cross color polarizer 35 Red cross color polarizer 36 Dummy glass 37 Dummy glass 100 Liquid crystal molecule 101 Transparent substrate 102 Opposite transparent substrate 103 Switching element 104 Transparent pixel electrode 105 Transparent common electrode 106 Liquid crystal alignment film 107 Liquid crystal alignment film 200 Liquid crystal molecule 201 Silicon substrate 202 Opposing transparent substrate 203 Switching circuit layer 204 Mirror pixel electrode 205 Transparent common electrode 206 Liquid crystal alignment Film 207 Liquid crystal alignment film 300 Transmission type liquid crystal element 301 Polarizer 400 Reflection type liquid crystal element 401 Polarizing beam splitter

Claims (7)

A TN-type first liquid crystal modulation element that modulates the polarization state of the first color light;
A TN-type second liquid crystal modulation element that modulates the polarization state of the second color light having a shorter wavelength than the first color light;
A TN-type third liquid crystal modulation element that modulates the polarization state of the third color light having a shorter wavelength than the second color light;
An image display device having an optical system for combining image light emitted from the three liquid crystal modulation elements,
Applying a first voltage to the first liquid crystal modulation element to give a half-wave phase difference to the first color light;
Applying a second voltage higher than the first voltage to the second liquid crystal modulation element to give a half-wave phase difference to the second color light;
An image display device, wherein a third voltage higher than the second voltage is applied to the third liquid crystal modulation element in order to give a half-wave phase difference to the third color light. A TN-type first liquid crystal modulation element that modulates the polarization state of the first color light;
A TN-type second liquid crystal modulation element that modulates the polarization state of the second color light having a shorter wavelength than the first color light;
A TN-type third liquid crystal modulation element that modulates the polarization state of the third color light having a shorter wavelength than the second color light;
An image display device having an optical system for combining image light emitted from the three liquid crystal modulation elements,
The retardation that the second liquid crystal modulation element gives to the incident light in a state where no voltage is applied is smaller than the retardation that the first liquid crystal modulation element gives to the incident light in a state where no voltage is applied.
The image display apparatus according to claim 1, wherein the retardation that the third liquid crystal modulation element gives to the incident light in a state where no voltage is applied is smaller than the retardation that the third liquid crystal modulation element gives to the incident light in a state where no voltage is applied. A TN-type first liquid crystal modulation element that modulates the polarization state of the first color light;
A TN-type second liquid crystal modulation element that modulates the polarization state of the second color light having a shorter wavelength than the first color light;
A TN-type third liquid crystal modulation element that modulates the polarization state of the third color light having a shorter wavelength than the second color light;
An image display device having an optical system for combining image light emitted from the three liquid crystal modulation elements,
The retardation that the first liquid crystal modulation element gives to incident light in a state in which no voltage is applied is substantially the same as the retardation that the second liquid crystal modulation element gives to incident light in a state in which no voltage is applied,
The image display device according to claim 1, wherein the retardation that the first and second liquid crystal modulation elements give to incident light in a state where no voltage is applied is greater than the retardation that the third liquid crystal modulation element gives to incident light in a state where no voltage is applied. A TN-type first liquid crystal modulation element that modulates the polarization state of the first color light;
A TN-type second liquid crystal modulation element that modulates the polarization state of the second color light having a shorter wavelength than the first color light;
A TN-type third liquid crystal modulation element that modulates the polarization state of the third color light having a shorter wavelength than the second color light;
An image display device having an optical system for combining image light emitted from the three liquid crystal modulation elements,
The retardation that the first liquid crystal modulation element gives to incident light when no voltage is applied is greater than the retardation that the second liquid crystal modulation element gives to incident light when no voltage is applied,
The retardation that the second liquid crystal modulation element gives to incident light in a state where no voltage is applied is substantially the same as the retardation that the third liquid crystal modulation element gives to incident light in a state where no voltage is applied. Display device. A TN-type first liquid crystal modulation element that modulates the polarization state of the first color light;
A TN-type second liquid crystal modulation element that modulates the polarization state of the second color light having a shorter wavelength than the first color light;
A TN-type third liquid crystal modulation element that modulates the polarization state of the third color light having a shorter wavelength than the second color light;
An image display device having an optical system for combining image light emitted from the three liquid crystal modulation elements,
In the state where the same voltage is applied to the three liquid crystal modulation elements, the three liquid crystal modulation elements are configured to give the same retardation to light of the same wavelength,
The amount of retardation applied when no voltage is applied to the three liquid crystal modulation elements corresponds to the half wavelength of the substantially central wavelength of the first color light,
The second and third liquid crystal modulation elements are provided with a retardation corresponding to a half wavelength of a substantially central wavelength of the second and third color lights by applying a voltage to each of the liquid crystal modulation elements. Image display device. A TN-type first liquid crystal modulation element that modulates the polarization state of the first color light;
A TN-type second liquid crystal modulation element that modulates the polarization state of the second color light having a shorter wavelength than the first color light;
A TN-type third liquid crystal modulation element that modulates the polarization state of the third color light having a shorter wavelength than the second color light;
An image display device having an optical system for combining image light emitted from the three liquid crystal modulation elements,
In a state where a certain voltage is applied, the first and second liquid crystal modulation elements are configured to give the same first retardation to light of a certain wavelength,
In the state where the certain voltage is applied, the retardation that the third liquid crystal modulation element gives to the light having the certain wavelength is different from the first retardation,
The amount of retardation applied when no voltage is applied to the first liquid crystal modulation element corresponds to a half wavelength of the substantially central wavelength of the first color light,
The amount of retardation applied when no voltage is applied to the third liquid crystal modulation element corresponds to a half wavelength of the substantially central wavelength of the third color light,
An image display device, wherein a voltage greater than 0 is applied to the second liquid crystal modulation element in order to provide a retardation corresponding to a half wavelength of a substantially central wavelength of the second color light. A TN-type first liquid crystal modulation element that modulates the polarization state of the first color light;
A TN-type second liquid crystal modulation element that modulates the polarization state of the second color light having a shorter wavelength than the first color light;
A TN-type third liquid crystal modulation element that modulates the polarization state of the third color light having a shorter wavelength than the second color light;
An image display device having an optical system for combining image light emitted from the three liquid crystal modulation elements,
In a state where a certain voltage is applied, the second and third liquid crystal modulation elements are configured to give the same first retardation to light of a certain wavelength,
In the state where the certain voltage is applied, the retardation that the first liquid crystal modulation element gives to the light having the certain wavelength is different from the first retardation,
The amount of retardation applied when no voltage is applied to the first liquid crystal modulation element corresponds to a half wavelength of the substantially central wavelength of the first color light,
The amount of retardation applied when no voltage is applied to the second liquid crystal modulation element corresponds to a half wavelength of the approximate center wavelength of the second color light,
An image display device, wherein a voltage greater than 0 (zero) is applied to the third liquid crystal modulation element in order to provide a retardation corresponding to a half wavelength of a substantially central wavelength of the third color light.