JP2005352251A - Color image display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive and bright color image display apparatus which hardly causes color breakup without degrading the resolution of a displayed image. <P>SOLUTION: The color image display apparatus is equipped with: a light source means 10 which emits, in time series, first illumination light including first and second wavelength bands and second illumination light including second and third wavelength bands; a polarization converting element 20 which converts the first and second illumination light into illumination light of linearly polarized light in a specified direction; a first polarizing plane rotating element 40 which rotates the polarizing plane of the illumination light by a predetermined angle; a wavelength selective reflecting element 50 which transmits illumination light in the second wavelength band in the first and second illumination light and reflects illumination light in the first and third wavelength bands; a second polarizing plane rotating element 60 which rotates the polarizing plane of the illumination light in the second wavelength band by a predetermined angle; and a reflecting plane 64 which reflects illumination light in the second wavelength band. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a color image display device using polarization control, and more particularly to a liquid crystal color image display device.

Conventionally, polarization control type liquid crystal light valves used in liquid crystal projectors include a transmission type and a reflection type, and a three-plate type, a two-plate type or a single-plate type projector is used for each.
The three-plate method is mainly a liquid crystal that corresponds to each color light separated by two dichroic mirrors or cross prisms that separate the white light source into the wavelength bands of the three primary colors (red, green, blue) of light. The light valve performs modulation based on the image signal of each color. Then, the three primary colors of modulated light are combined by a cross prism to generate a color image and enlarged and projected by a projection lens. The configuration differs depending on whether the liquid crystal light valve is a transmission type or a reflection type, but in any case, a three-plate configuration can provide high color reproducibility and high resolution, but the configuration is complicated and expensive. It is common to be a device.

  On the other hand, in the two-plate method, two color lights among the three primary colors of light are modulated by one liquid crystal light valve, and the other color light is modulated by another liquid crystal light valve. Various configurations for modulating two colored lights with a light valve have been proposed (see, for example, Patent Document 1). In the configuration of the two-plate liquid crystal projector using the reflective liquid crystal light valve described in Patent Document 1, red light and blue light are modulated by one liquid crystal light valve. The other liquid crystal light valve modulates green light, and a color adjustment valve such as a color wheel that switches between red light and blue light in a time-division manner is the front of the liquid crystal light valve or emits light source light. It is provided at the position immediately after. In this configuration, particularly when a color wheel is provided at a position immediately after the emission of the light source light, the light transmitted through the color filter of the color wheel is yellow light in which red light and green light are mixed, and blue light. It becomes an intermediate color of two colors of cyan light in which light and green light are mixed. This two-plate configuration is based on the image signal of each color by means of a liquid crystal light valve corresponding to means for generating two colors from a white light source as linearly polarized light orthogonal to each other and two colors separated by a polarizing beam splitter. Modulation. The two modulated lights are combined again by the polarization beam splitter and are magnified and projected by the projection lens, which is simpler than the three-plate system and has the merit that it can be made inexpensive. is there.

Further, the single plate system is responsible for modulation of the three primary colors of light with one liquid crystal light valve, and various configurations have been proposed.
The first configuration is a configuration comprising a white light source and a color wheel, and is a frame sequential method that modulates the three primary colors of light in a time-sharing manner. This method has the disadvantage that color breakup will occur unless the switching frequency of the color light to be modulated is raised, but the resolution itself can output the full number of pixels of the liquid crystal light valve, so high resolution can be achieved. Are suitable. Various methods for reducing color breakup have been proposed (see, for example, Patent Document 2). In the display device described in Patent Document 2, an intermediate color obtained by mixing two primary colors in addition to the three primary colors of light, red, green, and blue, is used as the filter color of the color wheel. As a result, color breakup occurring in the white portion of the image is reduced.

  Another configuration of the single plate method is a method in which each of the three primary colors of red, green, and blue is assigned to the three pixels of the liquid crystal light valve, and the resolution and brightness are reduced to 1/3 by itself. Although there are drawbacks, the structure itself is the simplest and suitable for an inexpensive device.

A liquid crystal light valve that modulates a plurality of colors by polarization control has also been proposed (see, for example, Patent Document 3). The color generation device described in Patent Document 3 has a laminated structure of three layers of liquid crystal, and a dichroic mirror for color light separation is sandwiched between the liquid crystal layers, so that the uppermost liquid crystal layer is red and the intermediate layer is The liquid crystal layer functions to turn on / off the blue color, and the lowermost liquid crystal layer controls the green color. Each of these three liquid crystal layers has a thickness that produces a phase difference of λ / 4 (where λ means a wavelength), and each color light reflected by the dichroic mirror reciprocates through each liquid crystal layer to λ / 2. Phase difference, that is, the action of rotating 90-degree polarized light. As a result, the polarization of red light, blue light, and green light can be independently controlled in two states of 0 degree or 90 degrees.
Japanese Patent No. 3057232 JP 2003-241714 A JP 2001-166273 A

  However, the above prior art is configured on the premise that the liquid crystal light valve is composed of pixels arranged in a two-dimensional plane. For this reason, one pixel in the plane of one liquid crystal light valve can basically only modulate monochromatic light, and it is difficult to make it high-resolution, bright, small, and inexpensive. Therefore, it is conceivable to construct a projector having both the characteristics of a single-panel type small and inexpensive, multi-plate type high resolution and bright by independently controlling the modulation of multiple colors with a single liquid crystal light valve. . However, the color generation device is only configured to generate the three primary colors as the light source, and is not a light valve that can control halftone display, and cannot function as a display element as it is.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an inexpensive and bright color image display device that does not reduce the resolution of a display image and that causes less color breakup. To do.

In order to achieve the above object, the present invention provides the following means.
The color image display device of the present invention is a color image display device that displays a color image corresponding to an input image signal to an observer, and includes first illumination light including first and second wavelength bands, and Light source means for emitting second illumination light including the second and third wavelength bands in time series, and first and second illumination light emitted by the light source means for linearly polarized illumination in a predetermined direction A polarization conversion element that converts light, a first polarization plane rotation element that rotates a polarization plane by a predetermined angle with respect to linearly polarized illumination light in a predetermined direction converted by the polarization conversion element, and the first polarization Wavelength selection that transmits the illumination light in the second wavelength band and reflects the illumination light in the first and third wavelength bands among the first and second illumination lights whose plane of polarization is rotated by the surface rotation element. A reflection element and an illumination of the second wavelength band transmitted by the wavelength selective reflection element; A second polarization plane rotating element that rotates the polarization plane at a predetermined angle with respect to the light, and a reflection plane that reflects the illumination light of the second wavelength band whose polarization plane is rotated by the second polarization plane rotation element It is characterized by providing.

  In the present invention, the first illumination light and the second illumination light are irradiated in time series by the light source means, and these illumination lights pass through the first polarization plane rotating element and rotate the polarization plane by a predetermined angle. . Then, the first and third wavelength bands to be reflected and the second wavelength band to be transmitted are separated by the wavelength selective reflection element. As a result, the first and third wavelength bands again pass through the first polarization plane rotation element and travel toward the polarization conversion element. In addition, the illumination light in the second wavelength band that has passed through the wavelength selective reflection element passes through the second polarization plane rotating element and is rotated by a predetermined angle. Furthermore, the illumination light in the second wavelength band is reflected by the reflection surface, and again passes through the second polarization plane rotation element, the wavelength selective reflection element, and the first polarization plane rotation element in this order and travels toward the polarization conversion element. Therefore, by using the first and second polarization plane rotating elements in a simple configuration, it is possible to display an inexpensive and bright color image with little color breakup without reducing the resolution of the display image. Become.

  In the color image display device of the present invention, at least the first polarization plane rotation element, the wavelength selective reflection element, the second polarization plane rotation element, and the reflection plane are integrally formed in a layered manner. It is characterized by that.

  In the present invention, since it is integrally formed, the amount of illumination light transmitted through the first polarization plane rotation element and directed toward the second polarization plane rotation element can be used without loss, and a brighter color can be obtained. An image can be displayed.

In the color image display device of the present invention, the illumination light of the first and third wavelength bands reflected by the wavelength selective reflection element has a polarization plane of a predetermined angle by the first polarization plane rotation element. The rotated first reflected light becomes
The illumination light of the second wavelength band reflected by the reflection surface is transmitted through the wavelength selective reflection element after the polarization plane is rotated by a predetermined angle by the second polarization plane rotation element, and then the first polarization plane. A second reflected light whose polarization plane is rotated by a predetermined angle by a rotating element is formed, and the color image is a combination of at least one of the first reflected light and the second reflected light. To do.

  In this invention, the illumination light in the first and third wavelength bands is reflected by the wavelength selective reflection element, and is directed to the polarization conversion element as the first reflected light, and the illumination light in the second wavelength band is reflected by the reflection surface. Then, it goes to the polarization conversion element as the second reflected light. Therefore, an image can be displayed by combining at least one of the first reflected light and the second reflected light.

The color image display device according to the present invention further includes a control unit that controls a polarization plane rotation angle of the first polarization plane rotation element and the second polarization plane rotation element for each pixel in accordance with an input image signal. It is characterized by providing.
In the present invention, by providing the control means, it is possible to accurately control the polarization plane rotation angles of the first polarization plane rotation element and the second polarization plane rotation element in accordance with the input image signal.

  In the color image display device of the present invention, the first and second wavelength bands included in the first illumination light are blue and green wavelength bands, and are included in the second illumination light. The second and third wavelength bands are green and red wavelength bands, and the wavelength selective reflection element reflects illumination light in the blue and red wavelength bands and emits illumination light in the green wavelength band. It is characterized by being transparent.

  In the present invention, since the first illumination light and the second illumination light are emitted in time series by the light source means, the green light is projected twice as long as the red light or the blue light. . Therefore, the amount of green light is greater than the amount of red or blue light. Using this green light amount margin, white balance can be obtained without dropping red light and blue light more than necessary. Is possible.

  In the color image display device of the present invention, the polarization conversion element is configured by a polarization beam splitter, and the first polarization plane rotation element and the second polarization plane rotation element are configured by liquid crystal elements. Features.

  In this invention, since only a necessary polarization component can be obtained by the polarization beam splitter, the first and second illumination lights can be efficiently modulated. In addition, since the first and second polarization plane rotation elements are composed of liquid crystal elements, high-precision phase difference control can be performed by changing the voltage applied to the liquid crystal elements and utilizing the birefringence of the liquid crystal elements. It becomes possible.

  In the color image display device of the present invention, the illumination light in the first and second wavelength bands is controlled to rotate the polarization plane by a predetermined angle by the first polarization plane rotation element, and the second The polarization angle for rotating the illumination light in the wavelength band by the second polarization plane rotation element is based on the polarization angle amount of the illumination light in the second wavelength band rotated by the first polarization plane rotation element. And a polarization plane rotation control means.

  In this invention, since the polarization plane rotation control means is provided, the polarization planes of the first polarization plane rotation element and the second polarization plane rotation element can be rotated at a predetermined angle, so that the phase control is performed with high accuracy. Is possible.

  Further, in the color image display device of the present invention, the polarization plane rotation control means includes a modulation amount of the illumination light in the second wavelength band and a modulation amount of the illumination light in the first or third wavelength band. The modulation amount corresponding to the polarization angle of the second polarization plane rotating element is input with the modulation amount corresponding to the polarization angle of the illumination light of the second wavelength band in the first polarization plane rotating element determined. A conversion table for output is provided.

  In the present invention, the illumination light in the second wavelength band is controlled by the second polarization plane rotation element in accordance with the state of the first polarization plane rotation element. It depends on the amount of light modulation. Therefore, by providing the conversion table, the phase control of the first polarization plane rotation element and the second polarization plane rotation element can be performed with high accuracy and high speed.

  In the color image display device according to the present invention, the polarization plane rotation control unit may modulate each of the illumination light of the second wavelength band included in the first illumination light and the second illumination light. And a second wavelength band modulation amount calculating means for determining so that a luminance level after modulation of the first illumination light and a luminance level after modulation of the second illumination light are substantially the same. To do.

  In this invention, since the second wavelength band modulation amount calculating means determines that the luminance level after modulation of the first illumination light and the luminance level after modulation of the second illumination light are substantially the same, the luminance difference Flickers and color breaks due to this can be reduced.

In the color image display device of the present invention, the first polarization plane rotation element rotates the polarization angle of illumination light in the first or third wavelength band by 90 degrees at the maximum, and the second polarization plane rotation element. Is characterized in that the polarization angle of the illumination light in the second wavelength band is rotated up to 180 degrees.
In the present invention, since the modulation amount of the illumination light in the first, second, and third wavelength bands can be utilized to the maximum extent, more color ranges can be realized.

The color image display device of the present invention is characterized in that the light source means includes at least a white light source and a color wheel.
In this invention, when the 1st illumination light and 2nd illumination light irradiated from the white light source are irradiated to a color hole, it becomes possible to isolate | separate the light from a white light source according to the color of a color wheel.

In the color image display device of the present invention, the light source means is composed of LEDs that independently emit at least three primary colors of blue, red, and green.
In the present invention, by emitting light of three colors of blue, red and green from the light source means, it is not necessary to increase the number of green LEDs unnecessarily in order to increase the maximum light quantity of the green LED. The effect that can be achieved is obtained.

The present invention has the following effects.
According to the color image display apparatus of the present invention, the light source means for emitting the first illumination light and the second illumination light in time series is provided in an inexpensive configuration of a single plate type, so that it is near the boundary of the white region. Since the colored region is small and the luminance difference between the colored region and the white region is also small, color breakup can be reduced.

Next, a first embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, a liquid crystal projector (color image display device) 1 according to this embodiment includes a light source (light source means) 10 and a polarization beam splitter (polarization conversion) that converts light emitted from the light source 10 into linearly polarized light. Element, hereinafter referred to as PBS) 20, a two-layer laminated reflective liquid crystal light valve 30 that controls the polarization direction of light reflected on the polarization separation surface 20 a of the PBS 20, a light source 10, and a two-layer laminated reflective liquid crystal light valve 30. And a signal processing unit 70 to be controlled.

  The light source 10 includes a white lamp 11 that emits white light, an integrator lens 12 that converts the light from the white lamp 11 into uniform diffused light, a telecentric optical system 13 that converts the light transmitted through the integrator lens 12 into parallel light, and a color And a wheel 14.

  The color wheel 14 is used when a liquid crystal projector is configured as a single plate configuration, and the light source 10 is divided into two color lights (cyan color light and yellow light), and one frame period is displayed in a field sequential manner in a plurality of fields. The color light is generated. The color wheel 14 is arranged one by one with a first line (cyan color filter) 14a and a second field (yellow color filter 14b) as shown in FIG. One frame has two fields. The color wheel 14 is a filter in which the first field 14a reflects a red wavelength and transmits a wavelength shorter than the red wavelength, and the second field 14b reflects a blue wavelength and emits a wavelength longer than the blue wavelength. It is a permeable filter, and a dichroic film can be used as a filter having these characteristics. Accordingly, the light source 10 includes the first illumination light (for example, cyan light) including the first and second wavelength bands and the second illumination light (for example, cyan light) including the second and third wavelength bands (for example, Yellow light) is emitted in time series. The first wavelength band included in the first illumination light is the blue wavelength band, the second wavelength band is the green wavelength band, and the second wavelength band included in the second illumination light is the second wavelength band. The wavelength band is a green wavelength band, and the third wavelength band is a red wavelength band.

  The PBS 20 converts cyan light and yellow light emitted from the light source 10 into linearly polarized illumination light in a predetermined direction. That is, in the PBS 20, the S-polarized component of each incident color light is reflected by the multilayer film sandwiched between the two prisms and is incident on the two-layer laminated reflective liquid crystal light valve 30. The P-polarized light component passes through the multilayer film as it is and is discarded outside.

  The two-layer laminated reflective liquid crystal light valve 30 has a transmissive liquid crystal panel (first polarization plane rotation) that rotates a polarization plane at a predetermined angle with respect to linearly polarized illumination light in a predetermined direction converted by the PBS 20 in an upper layer. Element) 40 and an interference filter that transmits illumination light in the green wavelength band and reflects illumination light in the red and blue wavelength bands among cyan light and yellow light whose polarization plane is rotated by a predetermined angle by the transmissive liquid crystal panel 40. A reflective liquid crystal panel (second polarization plane rotation) that rotates the polarization plane by a predetermined angle with respect to the illumination light in the green wavelength band that is transmitted through the interference filter film 50 and the film (wavelength selective reflection element) 50 Element) 60. The two-layer laminated reflective liquid crystal light valve 30 having a three-dimensional structure shown in FIG. 1 schematically represents only one pixel, but since it is an image display element, a plurality of pixels are arranged two-dimensionally. It is configured. The transmissive liquid crystal panel 40, the interference filter film 50, the reflective liquid crystal panel 60, and a reflective film (reflective surface) 64, which will be described later, are integrally formed in layers.

  The interference filter film 50 is disposed between the transmissive liquid crystal panel 40 and the reflective liquid crystal panel 60, and transmits only the illumination light in the green wavelength band and reflects other wavelengths. . That is, in this embodiment, the illumination light in the blue and red wavelength bands is reflected.

  Each pixel of the transmissive liquid crystal panel 40 includes a first transparent substrate 41 on the PBS 20 side on which the first transparent electrode 42 is patterned, and a reflection on which the second transparent electrode 44 is patterned in a position facing the first transparent substrate 41. The second transparent substrate 43 on the side of the liquid crystal panel 60, the upper liquid crystal layer 45 provided therebetween, and a liquid crystal driving switching element (not shown). As this switching element, a transparent transistor such as a zinc oxide compound is used. Between the first transparent electrode 42 and the first transparent substrate 41 or between the second transparent electrode 44 and the second transparent substrate 43. The aperture ratio is improved by laminating between them, and sufficient light can be supplied to the reflective liquid crystal panel 60 of the lower layer.

  Each pixel of the reflective liquid crystal panel 60 includes a third transparent substrate 61 from the transmissive liquid crystal panel 40 side, a third transparent electrode 62 patterned on the third transparent substrate 61, a lower liquid crystal layer 63, and a reflective liquid crystal. A reflective film 64 that reflects illumination light in the green wavelength band whose polarization plane is rotated by a predetermined angle on the panel 60 is laminated in this order, and a liquid crystal driving switching element (not shown) is formed below the reflective film 64. Yes.

The liquid crystal layers 45 and 63 are both driven in a birefringence mode, the upper liquid crystal layer 45 has a thickness that produces a phase difference of maximum λ _R / 4, and the lower liquid crystal layer 63 has a phase difference of maximum λ _G / 2. Has a thickness that produces Here, λ _R represents the wavelength of red light, and λ _G represents the wavelength of green light.

Further, the transmissive liquid crystal panel 45 and the reflective liquid crystal panel 63 are provided with a signal processing unit 70 that controls the polarization plane rotation angle for each pixel in accordance with the input image signal.
As shown in the block diagram of FIG. 3, the signal processing unit 70 is input to an image signal input unit 72 connected to a frame memory 71 that can be stored as an RGB digital image signal in units of frames, and the image signal input unit 72. Display element polarization plane rotation control unit (polarization plane) having a display element drive control unit (control means) 81 for controlling the polarization plane rotation angle of the transmissive liquid crystal panel 40 and the reflection type liquid crystal panel 60 for each pixel according to the received image signal. Rotation control means) 80, and a light source drive control unit 73 that controls the light source 10 based on a synchronization signal input from the display element polarization plane rotation control unit 80.

As shown in FIG. 4A, the display element polarization plane rotation control unit 80 converts an R conversion table (red conversion table) 82 between the modulation amount (gradation value) and the applied voltage in the upper liquid crystal layer 45 and B. Conversion table (blue conversion table) 83 and a G ₁ G ₂ calculating unit (second wavelength band modulation calculating means) for calculating the green modulation amount G ₁ of the first field 14 a and the green modulation amount G ₂ of the second field 14 b. ) and 84, as shown in FIG. 4 (b), the lower liquid crystal layer modulation amount in 63 (gradation value) and _{G 1} conversion table _{(G 1} conversion table) 85 and _{G 2} conversion table between the applied voltage and a _{(G 2} conversion table) 86. Accordingly, the polarization light for rotating the illumination light in the wavelength band of the green light by the reflective liquid crystal panel 60 is controlled while the illumination light of the red light and the blue light is controlled to rotate the polarization plane by a predetermined angle by the transmission type reflection panel 40. The angle is determined based on the amount of polarization angle of illumination light in the wavelength band of green light that is rotated by the transmissive reflective panel 40. That is, the two-layer laminated reflective liquid crystal bulb 30 is controlled based on the values of the conversion tables 82, 83, 85, 86.

  Here, FIG. 4A is a conversion table of modulation amounts of red light and blue light and applied voltages thereof. When each color of the image has an 8-bit gradation, 256 applied voltages are converted into red light and blue light. It is necessary to have each independently. This is because the phase difference corresponding to the modulation amount has wavelength dependency. FIG. 4B is a conversion table of the modulation amount of green light and its applied voltage. Since the green light controls the polarization in the lower liquid crystal layer 63 according to the state of the upper liquid crystal layer 45, the red light or This depends on the modulation amount of the blue light, and when each color of the image has an 8-bit gradation, it is necessary to have a total of 256 × 256 = 65536 applied voltages independently for the red light and the blue light. This is also due to the wavelength dependence of the retardation of the upper liquid crystal layer 45.

  The display element drive control unit 81 is paired via the first and second transparent substrates 41 and 43 so that the phase difference becomes a predetermined amount while red light or blue light reciprocates the upper liquid crystal layer 45. The voltage applied to the first and second transparent electrodes 42 and 44 is controlled. Further, the display element drive control unit 81 has a pair of first through the third transparent substrate 61 so that the phase difference becomes a predetermined amount while the green light reciprocates between the upper liquid crystal layer 45 and the lower liquid crystal layer 63. The voltage applied to the third transparent electrode 62 is controlled. In this way, the display element drive control unit 81 can freely control the polarization directions of the two wavelength bands at a time by controlling the upper liquid crystal layer 45 and the lower liquid crystal layer 63.

In particular, since the polarization direction of green light is rotated by the phase difference that occurs while reciprocating through the upper liquid crystal layer 45, the lower liquid crystal layer 63 uses the upper liquid crystal layer to obtain the target phase difference with respect to the modulation amount of the image signal. It is necessary to compensate for the 45 phase difference. The phase difference control amount by the lower liquid crystal layer 63 including this compensation amount is as follows.
When Df _Gu > Df _G , Df _Gl = λ _G − (Df _Gu −Df _G ) Equation 1)
When Df _Gu ≦ Df _G , Df _Gl = Df _G −Df _{Gu (} Formula 2)
Here, Df _G is a target phase difference (0 ≦ Df _G ≦ λ _G / 2) corresponding to the modulation amount of the green image signal, and Df _Gu is shifted while green light reciprocates through the upper liquid crystal layer 45. The phase difference (0 ≦ Df _Gu ≦ λ _G / 2 + δ) is satisfied, and Df _Gl is a phase difference (0 ≦ Df _Gl ≦ λ _G ) that shifts while green light reciprocates through the lower liquid crystal layer 63. The Df _Gu changes according to the target phase difference with respect to the modulation amount of the red or blue light image signal targeted by the upper liquid crystal layer 45.

Further, δ represents a shift amount considering the wavelength dependence of the phase difference caused by the upper liquid crystal layer 45. Here, as shown in FIG. 5, the wavelength dependence of the phase difference means the direction of the director of the liquid crystal and the birefringence in the direction orthogonal to the direction (light (ordinary light and extraordinary light) in the two directions). This is a phenomenon in which the phase difference between the ordinary light and the extraordinary light traveling in the liquid crystal layer becomes larger on the short wavelength light side than on the long wavelength light due to the difference in speed and the frequency does not change, and df _R ≦ df _G ≦ df _B. Here, df _R represents the phase difference of red light, df _G represents the phase difference of green light, and df _B represents the phase difference of blue light.

That is, in the upper liquid crystal layer 45, the display element drive control unit 81 controls the application of the voltage so that the red light or the blue light corresponding to the modulation amount based on the image signal becomes the target phase differences Df _R and Df _B. Will do. However, the phase difference Df _Gu of green light at this voltage is not equal to Df _R and Df _B except when Df _R = Df _B = 0, and in order to obtain the target phase difference Df _G of green light The phase difference by the lower liquid crystal layer 63 is controlled in consideration of the deviation amounts Δ _R (Df _R ) and Δ _B (Df _B ). Here, δ _R (Df _R ) means a function of Df _R , and δ _B (Df _B ) means a function of Df _B.
Df _Gu = Df _R + δ _R (Df _R ) or Df _Gu = Df _B + δ _B (Df _B ). Therefore, Formula 1) and Formula 2) can be expressed as follows.
When Df _Gu > Df _G , Df _Gl = λ _G − {Df _R + δ _R (Df _R ) −Df _G }.
Df _Gl = λ _G − {Df _B + δ _B (Df _B ) −Df _G } ・ ・ When the illumination light is cyan light
When Df _Gu ≦ Df _G , Df _Gl = Df _G − {Df _R + δ _R (Df _R )}.
Df _Gl = Df _G − {Df _B + δ _B (Df _B ) ·· This can be expressed as the case where the illumination light is cyan light.

  Also, each conversion table 82, 83, 85, 86 is a transmissive liquid crystal panel determined by the amount of modulation of illumination light in the wavelength band of green light and the amount of modulation of illumination light in the wavelength band of red light or blue light. The modulation amount corresponding to the polarization angle of illumination light in the wavelength band of green light at 40 is input, and the modulation amount corresponding to the polarization angle of the reflective liquid crystal panel 60 is output.

In addition, the G ₁ G ₂ calculating unit 84 determines that the modulation level of the green illumination light included in the cyan light and the yellow light is approximately equal to the luminance level after changing the cyan color light and the luminance level after modulating the yellow light. It is determined to be the same. In other words, flicker reduction can be achieved by allocating the distribution amount to each green field as shown below so that the luminance difference between the fields of the frame image formed by one rotation of the color wheel 14 is not generated as much as possible. . Hereinafter, a method of distributing green light to each field when one frame is composed of two fields will be described.
First, the relationship between the luminance L and the three primary colors R ₀ , G ₀ , B ₀ can be expressed as follows.
L = uR ₀ + vG ₀ + wB ₀ ; u, v, w are constants

If the first field of one frame is yellow illumination light, the second field is cyan illumination light, and the gradation value of one predetermined pixel is (R, G, B), the yellow illumination in the first field The modulated lights Y and Cy of the cyan illumination light in the light and the second field are as follows. Here, γr, γg, and γb are gamma correction values of R, G, and B, respectively.
Y = R ^γr + G ₁ ^γg ... Equation 3)
Cy = G ₂ ^γg + B ^γb Equation 4)
Where G ^γg = G ₁ ^γg + G ₂ ^γg Equation 5)

The luminance levels L _Y and L _Cy of _Y and _Cy are as follows from the equations 3) and 4).
L _Y = uR ^γr + vG ₁ ^γg Equation 6)
^{_{L Cy = vG 2 γg + wB}} γb ··· formula 7)
In order to set the luminance level of each field to the average luminance level (L _Y + L _Cy ) / 2, from Equation 5), Equation 6) and Equation 7)
^{_{G 1 = {G γg / 2}} + (wB γb -uR γr) / (2v)} 1 / γg ··· Equation 8)
^{_{G 2 = {G γg / 2}} + (uR γr -wB γb) / (2v)} 1 / γg ··· Equation 9)
However, if the conditions of G ₁ ≧ 0 and G ₂ ≧ 0 are not satisfied,
G ₁ = {G ^γg / 2} ^{1 / γg} Equation 10)
G ₂ = {G ^γg / 2} ^{1 / γg} Equation 11)
And

Here the green modulation amount of the first field 14a G ₁ and the green modulation amount G ₂ of the second field 14b may if 256 calculated as an integer value by the above equation, in Figure 4 (b) conversion table The form can be used as it is. In the above example, the green light distribution method in the drive control for reducing the luminance level variation between the fields has been described. However, when the above-mentioned calculation of G ₁ and G ₂ is more important than the flicker reduction, This can be done by halving the amount of green light for each field. This is possible by using only the above formulas 10) and 11), and these calculation formulas can be replaced with 256 different tables.

  Next, the operation of the liquid crystal projector 1 according to the present embodiment configured as described above will be described below. For simplicity of explanation, the wavelength dependence of the phase difference caused by the birefringence of the liquid crystal layer is not taken into consideration, and any wavelength passes through the liquid crystal layer to which the same voltage is applied by the display element drive control unit 81. Shall have the same phase difference.

The light emitted from the white lamp 11 enters the color wheel 14 via the integrator lens 12 and the telecentric optical system 13. When cyan light including blue light and green light that has passed through the first field 14a of the color wheel 14 enters the PBS 20, it becomes linearly polarized light (S-polarized light) in the PBS 20, and blue light and green light that have become S-polarized light. Cyan light containing the light enters the two-layer laminated reflective light valve 30. At this time, FIG. 6 shows the modulation amount of green light, which is another color included in cyan light, when the modulation amount of blue light included in cyan light is a predetermined intermediate value n (127 at the time of 8-bit gradation). In this example, the maximum value is 255 (at the time of 8-bit gradation, 255). Here, when the modulation amount of the blue light is a predetermined intermediate value n (= 127), it is assumed that circularly polarized light having a phase difference of λ _B / 4 is required at the time of entering the PBS 20.
The detailed operation of the signal processing unit 70 will be described later.

A schematic diagram of the polarization state in the forward path from the time when the linearly polarized light (S-polarized light) of cyan light is incident on the two-layer laminated reflective light valve 30 and reaches the reflective film 64 of the reflective liquid crystal panel 60 of the lower layer is shown in FIG. As shown. Linearly polarized (S-polarized) cyan light as incident light is incident from the PBS 20 at a predetermined angle with the director direction of the liquid crystal (the director directions of the upper and lower liquid crystal layers are the same). Then, it passes through the upper liquid crystal layer 45 to which a predetermined voltage V ₁ = V _B (n) having a modulation amount of a predetermined intermediate value n is applied, and becomes elliptically polarized light having a phase difference of λ / 8. Further, only green light of cyan light is transmitted through the interference filter film 50, and the green light which is elliptically polarized light has a predetermined voltage V ₂ = V _G (255, n, B) (the modulation amount is 255) ( Here, 255 is the modulation amount of green light, n is the modulation amount of blue light, and B is a color light type whose polarization is controlled in the upper layer). λ / 8 is added to obtain circularly polarized light of λ / 8 + λ / 8 = λ / 4.

Furthermore, the schematic diagram of the polarization state in the return path until the first reflected light from the interference filter film 50 and the second reflected light from the reflective film 64 of the two-layer laminated reflective light valve 30 are emitted is shown in FIG. As shown in FIG.
First, elliptically polarized blue light having a phase difference of λ / 8 reflected by the interference filter film 50 is transmitted again through the upper liquid crystal layer 45 toward the PBS 20 as shown in FIG. It becomes polarized light. Then, the P-polarized component is transmitted to the projection lens 21 side by the PBS 20, and predetermined modulation is performed on the blue light. Here, since the predetermined modulation is λ / 4 circularly polarized light, the P-polarized component and the S-polarized component are halved, so the PBS 20 has a predetermined intermediate value n (= 127) which is half of the light amount in linearly polarized light.

  On the other hand, circularly polarized green light having a phase difference of λ / 4 reflected by the reflective film 64 passes through the lower liquid crystal layer 63 along the optical path toward the PBS 20, as shown in FIG. It becomes polarized light. Then, by passing through the interference filter film 50 and passing through the upper liquid crystal layer 45, a phase difference of λ / 8 is further added, and a total of λ / 2 is obtained. Become. As a result, all of the linearly polarized (P-polarized) green light emitted from the two-layer laminated reflective liquid crystal light valve 30 passes through the PBS 20 and reaches the projection lens 21 side. Finally, the light emitted from the PBS 20 is projected by the projection lens 21 as a color light obtained by combining the blue light having the predetermined modulation amount and the green light having the maximum modulation amount, and is projected on the screen (not shown). Projected.

Subsequently, an example in which cyan light is incident, and the modulation amount of blue light included in the cyan light is the same as that in FIG. 6, and only the other color green light included in the cyan light is minimized. Is shown in FIGS.
First, a schematic diagram of the polarization state in the forward path from the time when the linearly polarized light (S-polarized light) of cyan light is incident on the two-layer laminated reflective light valve 30 and reaches the reflective film 64 of the reflective liquid crystal panel 60 of the lower layer, As shown in FIG. Linearly polarized (S-polarized) cyan light is incident as an incident light from the PBS 20 at a predetermined angle with the director direction of the liquid crystal. Then, it passes through the upper liquid crystal layer 45 to which a predetermined voltage V ₁ = V _B (n) having a modulation amount of a predetermined intermediate value n is applied, and becomes elliptically polarized light having a phase difference of λ / 8. Furthermore, the interference filter film 50 transmits only green light of cyan light, and the green light which is elliptically polarized light has a predetermined voltage V ₂ = V _G (0, n, B) (the modulation amount is 0). Here, 0 is the modulation amount of the green light, n is the modulation amount of the blue light, and B is the color light type whose polarization is controlled in the upper layer). / 8 is added, so that λ / 8 + 3λ / 8 = λ / 2, and linearly polarized light (P-polarized light) is obtained.

Furthermore, the schematic diagram of the polarization state in the return path until the first reflected light from the interference filter film 50 and the second reflected light from the reflective film 64 of the two-layer laminated reflective light valve 30 are emitted is shown in FIGS. As shown in FIG.
First, the elliptically polarized blue light having the phase difference λ / 8 reflected by the interference filter film 50 is transmitted again through the upper liquid crystal layer 45 toward the PBS 20 as shown in FIG. It becomes polarized light. Then, only the P-polarized light component is transmitted to the projection lens 21 side by the PBS 20, and predetermined modulation is performed on the blue light.

  On the other hand, the linearly polarized green light having the phase difference λ / 2 reflected by the reflective film 64 is added with a phase difference of 3λ / 8 when transmitted through the lower liquid crystal layer 63 along the optical path toward the PBS 20, as shown in FIG. Circularly polarized light of λ / 2 + 3λ / 8 = 7λ / 8 is obtained. Then, by passing through the interference filter film 50 and passing through the upper liquid crystal layer 45, the λ / 8 phase difference is further increased, and becomes a total λ, and becomes linearly polarized light (S-polarized light) whose polarization direction is rotated by 180 degrees. As a result, only the P-polarized light component is transmitted to the projection lens 21 side in the PBS 20, so all the linearly polarized (S-polarized) green light emitted from the two-layer laminated reflective liquid crystal light valve 30 reaches the projection lens 21. Will not. Finally, the light emitted from the PBS 20 is only the blue light having a predetermined modulation amount, and is projected by the projection lens 21 and projected onto a screen (not shown).

  Further, when yellow light including red light and green light becomes linearly polarized light (S-polarized light) in the PBS 20 in the second field 14 b of the color wheel 14 of the light source 10 and enters the two-layer laminated reflective liquid crystal light valve 30. Is similar to the method of controlling the voltage applied to the two-layer laminated reflective light valve 30 by the display element drive control unit 81 described above, and the display element drive control unit 81 emits red light in the upper liquid crystal layer 45. The modulation of red light and green light can be independently controlled by controlling the phase difference of green light in the upper liquid crystal layer 45 and the lower liquid crystal layer 63, respectively.

In this case, when the modulation amount of red light is n and the modulation amount of green light is m, the applied voltage to the liquid crystal is V ₁ = V _R (n) (where n is the modulation amount) in the upper liquid crystal layer 45. ), V ₂ = V _G (m, n, R) in the lower liquid crystal layer 63 (where m is the modulation amount of the green light, n is the modulation amount of the red light, and R is the color light type whose polarization is controlled in the upper layer) ). Further, the display element drive control unit 81 can similarly control any modulation amount other than the modulation amount.

Next, the detailed operation of the signal processing unit 70 will be described with reference to the block diagram shown in FIG.
First, an analog image signal such as NTSC or a digital image signal such as terrestrial digital input to the image signal input unit 72 is decoded by an image processing engine included in the image signal input unit 72 and temporarily stored in the frame memory 71. Stored. The R, G, and B values of each pixel from the frame memory 71 are input to the display element polarization plane rotation control unit 80.

  The R value is input to the R conversion table 82 from the frame memory 71, converted into an applied voltage value by the conversion table when the illumination light in FIG. 4A is yellow, and output to the display element drive control unit 81. Is done. Similarly, the B value is input to the B conversion table 83 from the frame memory 71, converted into an applied voltage value by the conversion table when the illumination light in FIG. 4A is cyan, and the display element drive control unit 81. Is output.

On the other hand, G value R, are input with B values G ₁ G ₂ calculating unit 84, the formula 8) to Formula 11) G ₁ is calculated based on the and G ₂ is G ₁ conversion table 85 and G ₂ Is output to the conversion table 86. The R value from the frame memory 71 and the G ₁ value output from the G ₁ G ₂ calculation unit 84 are input to the G ₁ conversion table 85, and conversion when the illumination light in FIG. 4B is yellow is performed. The applied voltage value is converted by the table and output to the display element drive control unit 81.

Similarly, the B value from the frame memory 71 and the G ₂ value output from the G ₁ G ₂ calculation unit 84 are input to the G ₂ conversion table 86, and the illumination light in FIG. 4B is cyan. Is converted into an applied voltage value by the conversion table and output to the display element drive control unit 81.

Then, the display device drive control unit 81, the input R, B, G _1, G applied voltage value for the ₂ first field (R and G _1), the field units of the second field (B and G ₂₎ Are stored in a memory (not shown). Based on the applied voltage value corresponding to each pixel for each field, an applied voltage of R or B is applied to the transmissive liquid crystal panel 40 of the two-layer stacked liquid crystal light valve 30, and G ₁ or G is applied to the reflective liquid crystal panel 60. Each of the _two applied voltages is driven and controlled. Further, the display element drive control unit 81 outputs a field number (first or second) for performing drive control to the two-layer stacked liquid crystal light valve 30 and its drive timing to the light source drive control unit 73 as a synchronization signal. The light source drive control unit 73 controls the rotation of the color wheel 14 based on the input synchronization signal, and the color light (yellow and cyan) from the light source unit 10 and the color light displayed by the two-layer stacked liquid crystal light valve 30. Control is performed so as to synchronize with the field image corresponding to.

According to the liquid crystal projector 1 according to the present embodiment, the display element drive control unit 81 controls the polarization plane rotation angles of the transmissive liquid crystal panel 40 and the reflective liquid crystal panel 60. Therefore, in the polarization control, the light quantity loss due to the green light passing through the upper and lower layers of the two-layer laminated reflective liquid crystal light valve 30 is larger than the red light and blue light passing through only the upper layer, but two intermediate colors (cyan and Yellow), the green light is projected onto the screen twice as long as the red light or blue light, so that the amount of green light is red and blue even if the above light loss is taken into account. Will be more. Using this green light amount margin, it is possible to achieve color balance (white balance) without reducing the amount of red and blue light more than necessary. Compared with a single-plate projector using a conventional primary color wheel A bright projector can be configured.
Further, since the transmissive liquid crystal panel 40 and the reflective liquid crystal panel 60 are constituted by liquid crystal elements, the polarization plane rotation angle of the transmissive liquid crystal panel 40 and the reflective liquid crystal panel 60 can be easily controlled by controlling the applied voltage. Can be changed.

Further, by providing the signal processing unit 70, it is possible to realize the liquid crystal projector 1 in which the two-layer laminated reflection type liquid crystal light valve 30 has a single plate configuration.
Furthermore, since the liquid crystal projector 1 can use the color wheel 14 composed of only intermediate colors, the color generated conspicuously in the white region of the image as compared with a normal single-plate projector using a primary color filter. There is an advantage that the cracking phenomenon can be reduced.

  Note that the above-described color breakup phenomenon is a phenomenon in which a color is added at the boundary of the white region when the observation position of the observer who observes the white region displayed by the surface sequential projector moves at high speed. This color breakup phenomenon will be explained using this. FIG. 12A shows the case of a conventional single-plate projector using three primary color (red, green, and blue) color wheels. When a white area is projected on a screen, red → green → blue. All fields constitute the maximum modulation amount and constitute one frame. If the observation position does not move during one frame period, this area is all recognized as white. However, if the observation position moves by a predetermined amount during one frame period, the imaging position on the retina as shown in FIG. As a reference, the positions of the three fields constituting the white area move relatively. As a result, a region where the three primary colors do not overlap occurs at the boundary portion of the white region, and the original white region is observed as an image having regions such as blue, cyan, white, yellow, and red.

  On the other hand, FIG. 12C shows the case where the two color wheels 14 of cyan and yellow according to the present invention and the two-layer laminated reflection type light valve 30 are used, and the white region similar to the above is a yellow → cyan field. All constitute the maximum modulation amount and constitute one frame. As described above, if the observation position does not move, the white area is all recognized as white. However, when the observation position moves, the white area is white when the image formation position on the retina as shown in FIG. Coloring occurs near the boundary of the region, and changes from yellow to white to cyan.

  The three primary colors (red, green, blue) color wheel shown in FIGS. 12 (a) and 12 (b) or the two color wheels 14 of cyan and yellow shown in FIGS. 12 (c) and 12 (d). In both cases, color breakup occurs, but the colored area of the cyan and yellow color wheel 14 is half that of the three primary color wheel, and the colored area and the white area. The difference in brightness is small. For this reason, the frequency observed as color breakage will decrease. Here, the yellow and cyan colors are colors determined by the ratio of red and green and the ratio of blue and green, and are not necessarily general yellow or cyan. To the last, the color mixture of red and green or blue and green was expressed as yellow or cyan.

Next, a second embodiment according to the present invention will be described with reference to FIG. In each embodiment described below, portions having the same configuration as those of the liquid crystal projector 1 according to the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.
The liquid crystal projector 90 according to the present embodiment is different from the first embodiment in the configuration of the light source 91.

  Light emitted from the light source 91 is composed of two colors, yellow light, which is a mixed color of red light and green light, and cyan, which is a mixed color of green light and blue light, as in the first embodiment. The LED emission is controlled so that the red LED 92 and the green LED 93 or the green LED 93 and the blue LED 94 are turned on simultaneously. The telecentric optical system 95 is an optical system for making the diffused light from the LED uniform light by using a rod integrator or the like and then making it substantially parallel light.

Next, the operation of the liquid crystal projector 90 according to the present embodiment configured as described above will be described below.
Similar to the first embodiment, the light source drive control unit 73 controls the light source 91 based on the input synchronization signal. The light source 91 controls the lighting of the LEDs independently by the red LED 92, the green LED 93, and the blue LED 94, and corresponds to the color light (yellow and cyan) from the light source 91 and the color light displayed by the two-layer laminated reflective light valve 30. It is controlled to synchronize with the field image.

  According to the liquid crystal projector 90 according to the present embodiment, in the case of the two-layer laminated reflection type liquid crystal light valve 30, green light can be constantly lit while taking a surface sequential structure, and therefore, compared with red light and blue light. You can earn an average amount of green light. In addition, in an LED consisting of three primary colors, it is necessary to increase the amount of green light at a predetermined ratio to the amount of red light and blue light in order to achieve color balance, and the brightness of the LED projector is the maximum light amount of the green LED. It will be specified in. If the conventional display element is configured as a single plate, the light source must be composed of more green LEDs than the red LEDs and blue LEDs in order to obtain the maximum light quantity of the green LEDs, and the light source section is large. There is a drawback of becoming. However, according to the above-described liquid crystal projector 90, it is not necessary to increase the number of green LEDs unnecessarily in order to increase the maximum light quantity of the green LEDs, and the effect that the light source unit can be reduced in size and brightness can be achieved.

  Since the three types of LEDs can finely adjust the light amounts of red light, green light, and blue light independently, the light path of green light is long with respect to red light or blue light in the two-layer laminated reflective liquid crystal light valve 30. Needless to say, the light source can compensate for the loss of light quantity and other manufacturing variations.

The technical scope of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.
For example, a configuration in which a PS polarization conversion element (not shown) is added to the light source 10 may be used. In this configuration, the light incident on the PBS 20 can be converted into linearly polarized light having only the S-polarized component, and the incident light from the light source 101 having the P-polarized component is not wasted in the PBS 20, and more A bright projector can be made.

  Further, in the description of the operation of the two-layer laminated reflection type light valve 30, the wavelength dependence of the phase difference caused by the birefringence of the liquid crystal layer was not taken into consideration. The phase difference may be controlled. In this case, the correction amount is included in the conversion table between the modulation amount of each color light and the applied voltage in advance, thereby enabling highly accurate phase difference control.

  Further, as the color wheel 14, when the driving speed of the two-layer laminated reflective liquid crystal light valve 30 as shown in FIG. 14 can be increased, the cyan color filter 14 a and the yellow color filter 14 b include the color wheel 15. It is also possible to adopt a 1-frame 4-field configuration in which two frames are arranged symmetrically. In the case of this configuration, flicker due to a luminance difference between fields and the above color breakup can be further reduced.

1 is a plan view showing a color image display device according to a first embodiment of the present invention. It is a top view which shows the color hole of the color image display apparatus of FIG. It is a block diagram which shows the signal processing part of the color image display apparatus of FIG. 2 is a conversion table of the color image display device of FIG. 1, in which (a) shows the relationship between gradation values and applied voltage in red and blue, and (b) shows the relationship between gradation values and applied voltage in green. . FIG. 2 is a schematic diagram showing a relationship between a director direction of a liquid crystal layer and a polarization direction of incident light in the color image display device of FIG. 1. It is a schematic diagram which shows the polarization state in the outward path | route of the incident light in the two-layer lamination | stacking reflection type liquid crystal light valve of FIG. It is a schematic diagram which shows the polarization state in the incident light in the two-layer lamination | stacking reflection type liquid crystal light valve of FIG. It is a schematic diagram which shows the polarization state in the incident light in the two-layer lamination | stacking reflection type liquid crystal light valve of FIG. It is a schematic diagram which shows another polarization state in the outward path | route of the incident light in the two-layer lamination | stacking reflection type liquid crystal light valve of FIG. It is a schematic diagram which shows another polarization state in the double path | route of incident light in the two-layer lamination | stacking reflection type liquid crystal light valve of FIG. It is a schematic diagram which shows another polarization state in the double path | route of the incident light in the two-layer lamination | stacking reflection type liquid crystal light valve of FIG. It is a schematic diagram explaining the color breaking phenomenon which generate | occur | produces in a white area | region, (a) and (b) shows the case where the color wheel of three primary colors (red, green, blue) is used, (c) and (d) Shows a case where a color hole of the color image display device of FIG. 1 is used. It is a top view which shows the color image display apparatus which concerns on 2nd Embodiment of this invention. It is a top view which shows the other example of the color wheel of the color image display apparatus of 1st and 2nd embodiment of this invention.

Explanation of symbols

1 Liquid crystal projector (color image display device)
10 Light source (light source means)
20 Polarizing beam splitter, PBS (polarization conversion element)
40 Transmission type liquid crystal panel (first polarization plane rotating element)
50 Interference filter film (wavelength selective reflection element)
60 Reflective liquid crystal panel (second polarization plane rotation element)
64 Reflective film (reflective surface)
80 Display element polarization plane rotation control unit (polarization plane rotation control means)
81 Display element drive control unit (control means)
82 R conversion table (red conversion table)
83 B conversion table (blue conversion table)
84 G ₁ G ₂ calculation section (second wavelength band modulation calculation means)
85 G ₁ conversion table (G ₁ conversion table)
86 G ₂ conversion table _{(G 2} conversion table)

Claims (12)

In a color image display device that displays a color image corresponding to an input image signal to an observer,
Light source means for emitting first illumination light including the first and second wavelength bands and second illumination light including the second and third wavelength bands in time series;
A polarization conversion element that converts the first and second illumination light emitted by the light source means into linearly polarized illumination light in a predetermined direction;
A first polarization plane rotation element that rotates a polarization plane at a predetermined angle with respect to linearly polarized illumination light in a predetermined direction converted by the polarization conversion element;
Of the first and second illumination light whose polarization plane is rotated by a predetermined angle by the first polarization plane rotation element, the illumination light of the second wavelength band is transmitted, and the illumination light of the first and third wavelength bands is transmitted. A wavelength selective reflection element that reflects
A second polarization plane rotating element that rotates the polarization plane by a predetermined angle with respect to the illumination light of the second wavelength band transmitted by the wavelength selective reflection element;
A color image display device comprising: a reflection surface that reflects illumination light in a second wavelength band whose polarization plane is rotated by a predetermined angle by the second polarization plane rotation element.   The at least said 1st polarization plane rotation element, the said wavelength selection reflection element, the said 2nd polarization plane rotation element, and the said reflection surface are comprised integrally in the layer form, It is characterized by the above-mentioned. Color image display device. The illumination light in the first and third wavelength bands reflected by the wavelength selective reflection element is
It becomes the first reflected light whose polarization plane is rotated by a predetermined angle by the first polarization plane rotation element,
The illumination light of the second wavelength band reflected by the reflecting surface is
The second polarization plane rotation element rotates the polarization plane by a predetermined angle and then passes through the wavelength selective reflection element to become the second reflected light having the polarization plane rotated by the first polarization plane rotation element.
The color image display device according to claim 1, wherein the color image is a combination of at least one of the first reflected light and the second reflected light.   2. The control unit according to claim 1, further comprising a control unit that controls a polarization plane rotation angle of the first polarization plane rotation element and the second polarization plane rotation element for each pixel in accordance with an input image signal. Color image display device. The first and second wavelength bands included in the first illumination light are blue and green wavelength bands,
The second and third wavelength bands included in the second illumination light are green and red wavelength bands,
2. The color image display device according to claim 1, wherein the wavelength selective reflection element reflects illumination light in a blue and red wavelength band and transmits illumination light in a green wavelength band. The polarization conversion element is composed of a polarization beam splitter,
2. The color image display device according to claim 1, wherein the first polarization plane rotation element and the second polarization plane rotation element are constituted by liquid crystal elements.   The illumination light in the first and second wavelength bands is controlled to rotate the polarization plane at a predetermined angle by the first polarization plane rotating element, and the illumination light in the second wavelength band is changed to the second wavelength band. A polarization plane rotation control unit configured to perform a polarization angle rotated by the polarization plane rotation element based on a polarization angle amount of the illumination light of the second wavelength band rotated by the first polarization plane rotation element. The color image display device according to claim 1, wherein:   The polarization plane rotation control means includes the first polarization plane rotation element determined by the modulation amount of the illumination light in the second wavelength band and the modulation amount of the illumination light in the first or third wavelength band. And a conversion table for outputting the modulation amount corresponding to the polarization angle of the second polarization plane rotation element, with the modulation amount corresponding to the polarization angle of the illumination light in the second wavelength band at The color image display device according to claim 7.   The polarization plane rotation control means calculates the amount of modulation of the illumination light in the second wavelength band included in the first illumination light and the second illumination light after the modulation of the first illumination light. 8. The color image display device according to claim 7, further comprising second wavelength band modulation amount calculating means for determining the luminance level and the luminance level after modulation of the second illumination light to be substantially the same.   The first polarization plane rotation element rotates the polarization angle of the illumination light of the first or third wavelength band by a maximum of 90 degrees, and the second polarization plane rotation element transmits the illumination light of the second wavelength band. 2. The color image display device according to claim 1, wherein the polarization angle is rotated up to 180 degrees.   2. A color image display device according to claim 1, wherein the light source means comprises at least a white light source and a color wheel.   2. The color image display device according to claim 1, wherein the light source means is composed of LEDs that independently emit at least three primary colors of blue, red, and green.

Images