JP3522591B2 - Image display device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device, such as a liquid crystal projector, which magnifies and projects light from a light source, which has passed through an image display element, onto a screen by a projection lens.

[0002]

2. Description of the Related Art A liquid crystal display element changes the optical characteristics of a liquid crystal by applying a driving voltage corresponding to an image signal to pixel electrodes arranged regularly in a matrix to display an image or characters. Is configured.
As a method of applying an independent drive voltage to the pixel electrode, a simple matrix method, a non-linear two-terminal element or a three-element method is used.
There is an active matrix method in which a terminal element is provided in a liquid crystal display element. In the case of the latter active matrix method, MIM (metal-insulator-metal) element or TF
A switching element such as a T (thin film transistor) element,
It is necessary to provide a wiring electrode for supplying a driving voltage to the pixel electrode.

When strong light is incident on this switching element, the element resistance in the OFF state is lowered, and not only the electric charge charged when a voltage is applied is discharged, but also the liquid crystal existing in the area where the switching element and the wiring electrode are formed. Since the regular drive voltage is not applied to the portion and the original display operation is not executed, there is a drawback that light leaks even in the black state and the contrast ratio is lowered.

Therefore, when the liquid crystal display element is a transmissive type, as shown in FIG. 18, a TFT substrate provided with a switching element such as a TFT 1501 and a pixel electrode is provided on an opposite substrate which faces the liquid crystal layer. It is necessary to provide a light blocking means called a black matrix 1502 to block the light entering the above-described light entrance region. Therefore, in the case of a transmissive liquid crystal display element, light is blocked by the black matrix 1502 in addition to the TFT 1501, the gate bus line 1503, and the source bus line 1504 each having a light blocking property, so that the pixel area is effectively occupied. The area of the pixel opening, that is, the aperture ratio is reduced.

Furthermore, it is difficult to form these switching elements and wiring electrodes in a certain size or smaller due to restrictions on their electrical performance and manufacturing technology. Therefore,
Along with the higher definition and smaller size of the liquid crystal display element, the smaller the pitch of the pixel electrodes, the lower the aperture ratio.

Therefore, in order to solve such a problem, a reflective liquid crystal display element has been developed. As shown in FIG. 19, the reflective liquid crystal display element has a reflective pixel electrode 1601 on a TFT 1501 as a switching element.
With the same liquid crystal display size, the aperture ratio can be made larger than that of the transmissive liquid crystal display element, which is very effective in improving the brightness in the projection liquid crystal display device. A method in which such a reflection type liquid crystal display element is applied to a projection type image display device is proposed in Electronic Display Forum 97 (pages 3-27 to 3-32) and Japanese Patent Laid-Open No. 5-158012.

In the electronic display forum 97, as shown in FIG. 20, the light emitted from the light source 1701 is reflected by the dichroic mirrors in the order of red, green and blue (hereinafter R, G,
(Referred to as “B”), and the respective lights are made incident on the corresponding polarization beam splitter (PBS) 1702. The polarization beam splitter 1702 splits the incident light into linearly polarized light components in two directions orthogonal to each other, and one light is incident on the corresponding reflection type liquid crystal display element 1704. The R, G, and B lights reflected by the reflective liquid crystal display element 1704 and having their polarization directions modulated enter the PBS 1702 again, are combined by the cross dichroic mirror 1703, and then are projected on the screen by the projection lens 1705. . This system is called a three-plate liquid crystal projection, and R, G, and B lights from a light source can be efficiently used, so that a very bright image can be realized.

In Japanese Patent Laid-Open No. 5-158012, R, G, and B lights from a light source are sequentially selected in a time-division manner and then made incident on a PBS. In PBS, incident light is separated into a P-polarized component and an S-polarized component, and one of them is incident on the image display element. (In this example, the S-polarized component is made incident). Signals are input to the image display element in synchronization with the incident color, and R, G, B
Is displayed as one segment (one frame). This method is called a time sequential method or a field sequential method.

In this example, in order to time-divide the R, G, B lights, a dichroic mirror for separating the white light from the light source into the R, G, B lights and a shutter for transmitting and blocking the respective lights are provided. Although configured in combination, there is also a method of using a rotating color filter having R, G, and B transmission regions as shown in FIG. In this system, only one reflective image display element and PBS are required, and an optical system for color separation and color synthesis is not required, so a low-cost and compact system can be realized.

[0010]

However, the above-mentioned projection type image display device using the reflection type liquid crystal display device has the following problems. The method proposed in the Electronic Display Forum 97 uses R, G, B
Since three reflective image display elements and PBSs corresponding to each color are required, and an optical system for color separation and a cross dichroic prism for color combination are also required, the system cost is very high. However, it has the disadvantage that the system size becomes very large.

In Japanese Patent Laid-Open No. 158012/1993, although the problem of the three-plate type can be solved, R, G, B lights from the light source are incident on the reflection type image display element in a time division manner.
For example, when R light is selected, G and B are practically unavailable, and the brightness decreases to 1/3 in principle.

Further, in this system, for example, 1/60
When displaying an image with one second as one frame, R, G, B
The display time assigned to each is about 5 msec, and the display must be performed within this time.
A device with a very high response speed is required. This is a CRT
This is a big problem when a liquid crystal having a relatively slow response speed is used.

Further, in this method, the three primary colors of R, G, and B are displayed in a time-division manner. Therefore, when a moving image is displayed or the line of sight is moved, the primary colors appear to be separated (hereinafter , Called color breaking), which deteriorates the image quality. In order to reduce this color breaking phenomenon, there is a method of increasing the driving frequency for displaying, but it is necessary to further increase the response speed of the element, which is extremely disadvantageous when liquid crystal is used.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an image display device using a reflective liquid crystal display element which is small, lightweight and bright.

[0015]

The image display device of the first constitution of the present invention divides the light source and the light of the three primary colors of red, green and blue from the light source into two groups of colored light, and Illumination means having a function of sequentially switching the color light of one group in a time-division manner and irradiating two colors of light of the three primary colors of red, green, and blue from the light source with different polarization directions from the other one. When,
A light separating unit that separates the light from the light source according to the polarization direction, a plurality of reflective image display elements that modulate the light separated by the light separating unit, and a light that is modulated by the reflective image display element are provided. And a projection means for projecting.

The image display device of the second structure of the present invention is an optical display device.
Having a source, red included in the light source, green, a function of selecting sequentially switching the color light of the two different groups, including two colors of the three primary colors of light blue, it from rotating color filter
That the color switching means, and said different two groups of colors that are common to the color light, or, in providing the first polarization control unit having a function of converting the polarization direction of the other two colors of light
Therefore, the light of the three primary colors of red, green, and blue from the light source is
Divide the colored lights into groups and divide the colored lights of the two groups into hours and minutes.
In addition to switching sequentially, the red, green and blue from the light source
If two of the three primary colors have different polarization directions from the other one
Illumination means having a function of irradiating the light and light from the light source
And a light separating means for separating the
Multiple reflective image display elements that modulate light separated by steps
And the light modulated by the reflective image display device is projected.
And a projection means .

An image display device having a third structure according to the present invention is the image display device having the first structure, wherein the illumination means includes two of the three primary color lights of red, green and blue included in the light source. A color switching unit having a function of sequentially switching and selecting a color light group including a color and the remaining one color group, and one color of the color light group including the two colors or the light of the other group. It is characterized by including a second polarization control means having a function of converting the polarization direction.

An image display device having a fourth structure according to the present invention is the image display device having the second structure, wherein the light separating means has a function similar to that of the first polarization control means on the projection means side. The polarization control means No. 3 is arranged.

According to a fifth aspect of the present invention, there is provided the image display apparatus according to the third aspect, which has the same function as the second polarization control means on the projection means side of the light separating means. The polarization control means 4 is arranged.

The image display device of the sixth structure of the present invention is the image display device of the second or fourth structure, wherein only one polarization direction is present on the light path on the light incident side of the first polarization control means. A polarization selection element that transmits light is arranged.

An image display device having a seventh structure according to the present invention is the image display device having the third or fifth structure, wherein only one polarization direction is present on the light incident side optical path of the second polarization control means. A polarization selection element that transmits light is arranged.

An image display device having an eighth structure according to the present invention is the image display device having the fourth or sixth structure, wherein only one polarization direction is present on the optical path on the light exit side of the third polarization control means. A polarization selection element that transmits light is arranged.

The image display device of the ninth structure of the present invention is the image display device of the fifth or seventh structure, wherein only one polarization direction is present on the light path on the light exit side of the fourth polarization control means. A polarization selection element that transmits light is arranged.

An image display device having a tenth structure of the present invention is
In the image display device having any one of the first to ninth configurations, the two reflective image display elements are arranged, one of which corresponds to one of the lights of the three primary colors, and the other of which is It is characterized by being compatible with the remaining two colors.

The eleventh image display device of the present invention is the second,
In the image display device having any one of the fourth, sixth, eighth, and tenth configurations, of the light of two colors other than the color common to the two different color lights selected by the color switching unit, It is characterized in that the selection time of the color light including the light of the weaker spectral intensity is set longer than the selection time of the other color light.

An image display device having a twelfth structure of the present invention is
In the image display device having any one of the second, fourth, sixth, eighth, and tenth configurations, only one of the two different color lights selected by the color switching unit includes a green component. The selection time of the color light containing green is set longer than the selection time of the other color light.

An image display device having a thirteenth structure of the present invention is
In the image display device having any one of the third, fifth, seventh, ninth, and tenth configurations, among the color lights selected by the color switching unit, the color light including the light with the weaker spectral intensity of the light source is selected. The selection time is made longer than the selection time of the other color light.

An image display device having a fourteenth structure of the present invention is
In the image display device having any one of the third, fifth, seventh, ninth, and tenth configurations, among the color lights selected by the color switching means, the selection time of the color light containing green is set to the other color light. It is characterized in that it is longer than the selection time.

An image display device having a fifteenth structure of the present invention is
In the image display device having any one of the second, fourth, sixth, eighth, and tenth configurations, the color common to the two different colored lights is the light having the weakest spectral intensity of the corresponding light source. Characterize.

An image display device having a sixteenth structure of the present invention is
In the image display device having any one of the second, fourth, sixth, eighth, and tenth configurations, the color common to the two different colored lights is green.

An image display device having a seventeenth structure of the present invention is
In the image display device having any one of the second to sixteenth configurations, the color switching unit has an area for transmitting all three primary colors of red, green, and blue.

The operation of the present invention will be described below. According to the first configuration, since R, G, and B single colors are displayed in a time-sharing manner, the brightness is reduced to 1/3 as compared with that of a system using three image display elements. However, by using this method, two different colors including two colors of R, G, and B
Since one color light is used, two of the three primary colors can always be used, and the brightness can be dramatically improved without increasing the system size.

Further, in the present method, since the color lights of the two different colors are sequentially switched and displayed as described above, color braking between the color lights occurs, but they appear to be separated into three primary colors as in the conventional case. Instead, it is confirmed as being separated into two colors, and because this color light contains two colors of R, G, and B, it is confirmed that the color braking phenomenon is greatly alleviated by humans. .

According to the second configuration, the light source and the light source
Light of the three primary colors of red, green, and blue into two colored light groups
The color lights of the two groups are sequentially switched in time division.
Together with the light of the three primary colors of red, green and blue from the light source,
The function of irradiating two colors with different polarization directions from the other one
The illuminating means that it has and the light from the light source depending on the polarization direction
The light separating means for separating and the light separated by the light separating means
Multiple reflective image display elements for modulation and the reflective image
And a projection means for projecting the light modulated by the display element.
Therefore, the same operation and effect as the first configuration are obtained. Addition
Also, the color switching means sequentially selects two different color lights, and the first polarization control means rotates the polarized light of either the color common to both color lights or the other two colors, thereby efficiently determining the predetermined color light. The light can be made incident on the corresponding reflection type image display device, and the brightness can be further improved.

Further, in the conventional method, as shown in FIG. 21, it is necessary to divide the area through which each color of R, G, and B is transmitted into three, but when this method is used, as shown in FIG. Since the area is divided into two different colored light areas, the requirement for the response speed is basically relaxed by a factor of 1.5 (brightness is also ideally improved by a factor of 1.5). In addition, since the color contained in the two color lights is always applied to the reflective image display element, the request for the response speed is the same as that of the conventional three-plate system, and the improvement in brightness is tripled. it can.

As the first polarization control means, for example, US
Devices such as those disclosed in P5,751,384 can be used. This element has a function of rotating a polarized light of only a light in a specific wavelength range by laminating a plurality of wave plates with their axes being changed in angle, and for example, an element for rotating B polarized light was used. In this case, as shown in FIG. 5, when white linearly polarized light is incident on this element, the R and G polarization directions of the emitted light are maintained, and only the B polarization direction can be rotated.

According to the third configuration, each time the color switching unit switches the color light incident on the light separating unit, the corresponding color light is emitted to each reflection image display element and the corresponding color light is not emitted. ,Repeated. By utilizing the time when the reflective image display element is not irradiated with colored light, an image signal can be written in the reflective image display element, and the polarization direction of light can be modulated in accordance with the image signal when the colored light is irradiated.

Up to now, in the field-sequential system using a liquid crystal panel, for example, light cannot be used from the time when an electric field is applied to the liquid crystal until the liquid crystal molecules completely react (response time of the liquid crystal). However, in the present invention, it is not necessary to set a blanking time for writing an image signal by using the non-irradiation time of light as described above, and the light use efficiency is further improved. You can

According to the fourth structure, the third polarization control means having the same function as the first polarization control means is arranged on the photographing means side of the light separating means, so that the light is emitted in different polarization directions. It is possible to use a polarizing screen that can align the polarization directions of light and can maintain a high contrast ratio even under bright illumination. Polarizing screen
A polarizing plate is attached to the screen surface and cuts half of the incident light with random polarization. If the transmission axis of this polarizing plate and the polarization direction of the light emitted from the projection are made to coincide with each other, the incident light from the projection is hardly cut, so that the influence of external light can be halved and a high contrast ratio can be maintained.

According to the fifth construction, the fourth polarization control means having the same function as that of the second polarization control means is arranged on the projection means side of the light separating means, similarly to the fourth construction. Since the polarization directions of lights emitted in different polarization directions can be aligned, a high contrast ratio can be maintained even under bright illumination by using a polarizing screen.

According to the sixth structure, the polarization selecting means is the first
Since the linearly polarized light can be incident on the first polarization control means by arranging the polarization control means on the light path on the light incident side of the polarization control means,
Color separation and polarization separation can be efficiently performed by the first polarization control unit and the light separation unit, and a bright image with a high contrast ratio can be realized.

According to the seventh configuration, the polarization selecting means is provided in the second
Since the linearly polarized light can be made incident on the second polarization control means by arranging the polarization control means on the optical path on the light incident side of the polarization control means, the efficiency of the second polarization control means and the light separation means can be improved. Color separation and polarization separation can be performed well, and a bright image with a high contrast ratio can be realized.

According to the eighth structure, the polarization selecting means is provided in the third structure.
By providing on the optical path on the light emission side of the polarization control element, the light originally returned in the light source direction by the light separation element is cut by the polarization selection means even when passing through the light separation element.
An image with a high contrast ratio can be realized.

According to the ninth structure, the polarization selecting means is provided in the fourth structure.
By providing it on the optical path on the light emission side of the polarization control element, the light originally returned in the light source direction by the light separation element is cut by the polarization selection means even if it passes through the light separation element as in the eighth configuration. Therefore, an image with a high contrast ratio can be realized.

According to the tenth structure, two reflective image display elements are arranged, one reflective image display element is any two colors of R, G, and B, and the other is the remaining one. In the conventional method, the colors of R, G, and B are displayed one by one in order to deal with the colors, but since the lights of two colors can be used at the same time, the brightness can be dramatically improved.

According to the eleventh configuration, the selection time of the color light including the light having the weaker spectral intensity of the light source among the lights of two colors other than the color common to the two different color lights selected by the color switching means. Is longer than the selection time of the other color light, it is possible to relatively increase the light amount of light with a weak spectrum even when using a lamp having a spectral intensity bias (for example, a metal halide lamp or a halogen lamp).
The white balance can be improved.

Conventionally, when used in an AV projection that emphasizes white balance, the white balance was adjusted by cutting light with a strong spectral distribution, so the brightness was greatly reduced. In this method, the decrease in brightness is minimized, which is very advantageous for AV projection.

According to the twelfth configuration, the green component is included in only one of the two different colored lights selected by the color switching means, and the selection time of the colored light containing green is set to that of the other colored light. By making it longer than the selection time, it is possible to increase the amount of green light that has high visibility and greatly affects the brightness, and thus it is possible to improve the brightness. As a result, even if the white balance is deviated, when used for data projection, the white balance is not considered important, so that it is not a big problem.

According to the thirteenth configuration, among the color lights selected by the color switching means, the selection time of the color light including the light having the weaker spectral intensity of the light source is made longer than the selection time of the other color light. Similar to the eleventh configuration, even if a lamp having a spectral intensity bias (for example, a metal halide lamp or a halogen lamp) is used, the light amount of light with a weak spectrum can be relatively increased, and the white balance is improved. can do.

According to the fourteenth structure, among the colored lights selected by the color switching means, the selection time of the colored light containing green is made longer than the selection time of the other colored light, so that the twelfth structure is achieved. It is possible to increase the amount of green light, which has high luminosity and has a great effect on brightness, and thus to improve brightness.

According to the fifteenth configuration, the color common to the two different colored lights is the light having the weakest spectral intensity of the corresponding light source, so that the corresponding reflection of this light is always incident on the image display device. Therefore, a good white balance can be obtained even if a lamp having a spectral intensity bias is used (for example, a metal halide lamp or a halogen lamp).

Conventionally, when used in an AV projection in which white balance is important, the white balance is adjusted by cutting light with a strong spectral distribution, so that the brightness is greatly reduced. Then, since the decrease in brightness is suppressed to the minimum, it is very advantageous for the AV projection.

According to the sixteenth structure, by making the color common to the two different colored lights green, it is possible to increase the amount of green light which has a high luminosity factor and has a large effect on brightness, thereby increasing the brightness. Can be improved. As a result, even if the white balance is deviated, the white balance is not considered important when used for data projection, so that it is not a big problem.

According to the seventeenth structure, since the color switching means has the transparent area, all the R, G, and B light is transmitted in that area, and when white display is performed on the screen, The brightness can be improved.

[0055]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below with reference to the drawings. (Embodiment 1) FIG. 1 is a schematic view of a projection type color image display device of the present invention. In this embodiment, as the light source 101,
UHP made by Philips with 120W and 1.4mm arc length
A lamp (high pressure mercury lamp) was used. In addition to this, a halogen lamp, a xenon lamp, or a metal halide lamp can be used as the light source. On the back surface of the light source 101 is an elliptical mirror 1 for focusing the light from the light source on its second focal point.
02 is arranged. In the vicinity of the second focus of the elliptic mirror 102, as shown in FIG. 2, a rotating color having a region that transmits cyan (color light containing B and G components) and magenta (color light containing B and R components) light. A filter 103 is arranged, and a glass rod 104 is arranged in front of it. The glass rod 104 reflects light inside and transmits the light, and is arranged so that its light emitting surface substantially forms an image on a reflective liquid crystal display element 110 described later.

On the light emitting surface of the glass rod 104, the light is repeatedly totally reflected inside the rod, so that the illuminance distribution is substantially uniform. Accordingly, the reflective liquid crystal display device 110
The illuminance distribution of light incident on can be improved. The light emitted from the glass rod 104 enters the illumination lens 105 and the field lens 106, and after being made into substantially parallel light,
It enters the polarizing plate 107. In the polarizing plate 107, only light in the direction perpendicular to the paper surface is transmitted and is made incident on the polarization control element 108.

The polarization control element 108 has the characteristics shown in FIG. 3, and only the light of the B component of the incident light is rotated in the direction parallel to the paper surface and is incident on the PBS 109. In FIG. 3, the solid line shows the characteristics of the light reflected by the PBS in the optical system shown in FIG. 4, and the broken line shows the PBS.
Is the characteristic of the light transmitted through.

In this embodiment, as the polarization control element 108, the element disclosed in USP 5,751,384 is used. This element has a function of rotating a polarization of only light in a certain specific wavelength range by laminating a plurality of wave plates with their axes being changed in angle, and for example, as in this embodiment, B
When an element for rotating the polarized light is used, as shown in FIG. 5, when white linearly polarized light is incident on this element, the polarization directions of R and G of the emitted light are maintained and only the polarization direction of B is rotated. Can be made.

In the present embodiment, the above-mentioned element is used as the polarization control element 108, but any element having the same function can be used, for example, cholesteric liquid crystal or the like may be used. When the light emitted from the polarization control element 108 enters the PBS 109, the R and G lights are converted into PBS.
Since it is S-polarized with respect to 109, it is reflected, and the light of B is P
It transmits because it becomes polarized light. The light transmitted and reflected by the PBS 109 corresponds to the corresponding reflection type liquid crystal element 110-
After being incident on 1, 2 and modulated according to the image signal,
Only the light, which is reflected toward the PBS 109 again and whose polarization direction is modulated, enters the projection lens 111 and is projected on the screen. As the reflective liquid crystal element 109, 0.9
Type XGA panel, Nem with a response speed of 2 msec to 3 msec
An atic liquid crystal was used. In addition to the above, any liquid crystal mode such as a ferroelectric liquid crystal having a relatively high response speed can be used.

At this time, since the rotary color filter 103 having the cyan and magenta transmissive regions rotates at 1/60 second, the time allocated to each of cyan and magenta is about 8 msec. The color switches. Of these, B, which is common to the two color lights, is always transmitted through the PBS 109 regardless of the rotation of the rotary color filter 103 and is incident on the reflective liquid crystal element 110-2. On the other hand, when the light of B escapes from cyan and magenta, it becomes light of R and G. The R and G lights are sequentially switched at the above speed and enter the reflective liquid crystal element 110-1. Therefore, in one round of the rotary color filter 103,
The R, G, and B lights are modulated by the reflective liquid crystal element 110.

In this embodiment, the rotary color filter 1
Although 03 was rotated at 1/60 seconds, it may be double speed or higher speed. At this time, the rotating color filter 10
The same effect can be obtained by increasing the number of divisions of the color filter as shown in FIG. 6 instead of increasing the rotation speed of 3. A polarization control element 112 and a polarizing plate 113 are arranged between the PBS 109 and the projection lens 111. The polarization control element 112 uses the same thing as the polarization control element 108, and has the function of rotating the polarization direction of B light only and aligning the R, G, and B polarization directions. The polarizing plate 113 cuts out leakage light of the light originally cut by the PBS 109 out of the light from the polarization control element 112, so that the C.I. R. Improve. When the projection is constructed with the above-mentioned configuration, the brightness can be improved by about 1.5 times as compared with the conventional single plate type field sequential system.

In this embodiment, the polarization control elements 108 and 112 that rotate the polarization of the B light are used, but the polarization directions of the R and G may be rotated, and the P and S polarizations of the respective colors incident on the PBS 109 may be rotated. May be replaced. Further, in the present embodiment, white is separated into R, G and B, but any combination such as G, B and R is possible. In this case, it is only necessary to change the color of light rotated by the polarization control elements 108 and 112. Further, in the present embodiment, the polarizing plate and the polarization control element are arranged on both the light incident side and the light emitting side of the PBS 109, but the polarizing plate 113 and the polarization control element 112 on the light emitting side are not necessarily required.

(Second Embodiment) FIG. 7 is a schematic view of a projection type color image display device according to a second embodiment of the present invention. In this embodiment, only the characteristic of the rotating color filter is different from that of the first embodiment. Therefore, the parts corresponding to those of the first embodiment are denoted by the same reference numerals and detailed description thereof will be omitted. In this embodiment,
As shown in FIGS. 8A and 8B, the rotary color filter 701-1 or the magenta and yellow (light including the R and G components) regions in which the magenta region is about 10% larger than the cyan region is included. Rotating color filter 701
-2 is used. However, when the magenta and yellow rotating color filters 701-2 are used, the polarization control elements 702 and 70 that rotate only the R polarization direction having the characteristics shown in FIG. 9 are used instead of the polarization control elements 108 and 112.
3 was used. As the polarization control elements 702 and 703, those that rotate the polarization direction of only G or B can be used.

The rotating color filter 701 shown in FIG.
In the case of -1, the magenta region including R is larger than that used in the first embodiment, and thus the light of R having a weak spectrum intensity becomes strong. The rotating color filter 70 of FIG.
When 1-2 is used, since R is commonly contained in magenta and yellow, the rotary color filter 701-
Since the reflective liquid crystal display element 110 is always irradiated regardless of the second color region and the rotation speed, the R light can be intensified as in the case of FIG. 8A.

U made by Philips used in this embodiment
Since the HP lamp has a weak R spectrum and poor white balance, a good white balance can be obtained by using the rotary color filter 701 having the above characteristics. This rotating color filter 701-1,
When the projection is configured by using 701-2, it is possible to obtain a very good white balance as the AV projection without significantly lowering the brightness as compared with the first embodiment.

In the present embodiment, a UHP lamp having a weak R spectral intensity is used, but when a lamp having different R, G, B spectral intensities is used, a weak color of the spectrum of the rotary color filter 701 is included. The same effect can be obtained by enlarging the area of the colored light that is present, or by making the color common to two different colored lights a light with a weak spectrum. For example, when a halogen lamp is used, unlike the above-mentioned UHP lamp, the R light is strong and the B light is weak. Therefore, the area of the colored light containing B should be increased or magenta and cyan should be used. B may be a color commonly included in two different colored lights.

(Embodiment 3) FIG. 10 is a schematic view of a projection type color image display device according to a third embodiment of the present invention. In this embodiment, only the rotating color filter is different from that of the first embodiment, and therefore, the portions corresponding to those of the first embodiment are denoted by the same reference numerals and detailed description thereof will be omitted. This embodiment is shown in FIG.
Rotation color filter 1001-where the cyan region as shown in (a) and (b) is about 10% larger than magenta
A rotary color filter 1001-2 having a region of 1 or cyan and yellow is used. However, when the cyan and yellow rotating color filters 1001-2 are used, the polarization control elements 108 and 112 are replaced with polarization control elements 1002 and 1003 having the characteristics shown in FIG. . Polarization control element 1
Besides 002 and 1003, those that rotate the polarization directions of only R and B can be used.

As a result, when the rotary color filter 1001-1 shown in FIG. 11A is used, the cyan light containing G, which has high visibility, becomes strong, and the brightness can be improved. When the rotary color filter 1001-2 shown in FIG. 11B is used, G is commonly contained in both cyan and yellow, so that the color region and the rotation speed of the rotary color filter 1001-2 are large. regardless of,
Since the reflective liquid crystal display element 110-2 is always illuminated,
As in FIG. 11A, the G light can be intensified.
When the above-described two types of rotary color filters 1001-1 or 1001-2 are used, the rotation color filter 1001-1 of FIG. When the rotating color filter 1001-2 of (b) was used, the brightness could be improved by about 1.5 times. By making G stronger, the white balance becomes a range closer to G, but it is in a range that can be sufficiently used as a data projection.

(Embodiment 4) FIG. 13 is a schematic diagram of a projection type color image display device according to a fourth embodiment of the present invention. In this embodiment, only the rotating color filter is different from that of the first embodiment, and therefore, the portions corresponding to those of the first embodiment are denoted by the same reference numerals and detailed description thereof will be omitted. In the present embodiment, as the rotating color filter 1301, as shown in FIG. 14, in addition to the cyan and magenta transmissive regions, 15 transparent regions are provided.
Uses% added.

In this system, when performing color display,
As in the first embodiment, the cyan and magenta areas are used,
At the time of white display, light that further passes through the transparent area is used. Since all the R, G, and B light is transmitted through the transparent area, the brightness can be improved. When this rotary filter 1301 is used, compared with the first embodiment without changing the white balance and the R, G, B color purity,
We were able to achieve a brightness improvement of about 1.2 times. The method of providing the transparent area in the rotary color filter 1301 used in this embodiment can be similarly used in the rotary color filters 701 and 1001 used in the second and third embodiments. Further, in the present embodiment, the cyan and magenta filters are used as the rotary color filter 1301, but any combination of different colored lights including two of the three primary colors of R, G and B such as magenta and yellow can be used. But it is okay.

(Fifth Embodiment) FIG. 15 is a schematic view of a projection type color image display device according to a fifth embodiment of the present invention. In this embodiment, parts corresponding to those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. In this embodiment, a rotary color filter 1901 having a cyan area and an R area as shown in FIG. 16 is used. As the rotating color filter, one having a magenta region and a G region, and a yellow region and a B region may be used in addition to the above. The size of these colored light regions may be adjusted according to the purpose. Further, as in the case of the fourth embodiment, the transmission regions that transmit all the R, G, and B lights are rotated by a color filter. May be provided.

In the polarizing plate 107, only the light perpendicular to the paper surface is transmitted and is made incident on the polarization control element 108.
The polarization control element 108 has the same function as that used in the first embodiment, and only the light of the R component of the incident light is rotated in the direction parallel to the paper surface and is incident on the PBS 109. The light emitted from the polarization control element 108 is PBS.
When incident on 109, the B and G lights are reflected by the PBS 109 because they are S-polarized. Then, after that, the B light is reflected by the dichroic mirror 1902 and is incident on the reflective liquid crystal element 110-1, and the G light is transmitted through the dichroic mirror 1902, and the reflective liquid crystal element 110 is transmitted.
Incident on -2. On the other hand, the R light is P-polarized, so P
The light passes through the BS 109 and enters the reflective liquid crystal element 110-3.

The R, G, and B lights modulated in accordance with the image signal by the reflective liquid crystal elements 110-1, 2, and 3 are again converted into P light.
Only the light that is reflected toward the BS 109 and whose polarization direction is modulated enters the projection lens 111 and is projected on the screen. As the reflective liquid crystal element 110, 0.9 type XGA
In the panel, Nematic liquid crystal having a response speed of 6 msec was used. At this time, R and cyan (color light composed of B and G)
Light is time-divisionally PB'd by the rotating color filter 1901.
Since it is incident on S109, for example, in the field 1 (cyan area of the rotating color filter 1901), B,
G enters the reflective liquid crystal elements 110-1 and 110-2, respectively, and in field 2 (R region), the R light enters the reflective liquid crystal element 110-3. Where field 1
Then, since the R light is not incident on the reflective liquid crystal element 110-3, the next field 2 within this time is set in advance.
The image signal displayed by can be written in the reflective liquid crystal element 110-3.

Similarly, in the reflective liquid crystal elements 110-1 and 110-2, image signals corresponding to B and G can be written in the field 2. In this embodiment, since the rotary color filter 1901 is rotated for 1/60 seconds, the time assigned to the field 1 and the field 2 is about 8 msec, and the color is switched at each time.
Therefore, when a liquid crystal material having a response speed faster than this time is used, an image can be displayed without a blanking time, so that the brightness can be improved.

In this embodiment, the rotary color filter 1
Although the 901 is rotated for 1/60 seconds, the speed may be doubled or higher. At this time, the rotating color filter 10
The same effect can be obtained by increasing the number of divisions of the color filter instead of increasing the rotation speed of 3. Further, even if the response speed of the liquid crystal is slower than the time assigned to each field, the blanking time can be shortened, so that there is an effect of improving brightness.

Although three reflective liquid crystal elements are used in this embodiment, two reflective liquid crystal elements may be used as shown in FIG. In this case, one of them corresponds to two colors of R, G, and B, so a color filter may be installed in the reflective liquid crystal element. When a liquid crystal material having a sufficiently high response speed is used, it is not necessary to irradiate two colors of light in a time-division manner, and R, G, and B can be made incident at the same time.

A polarization control element 112 and a polarizing plate 113 are arranged between the PBS 109 and the projection lens 111.
As the polarization control element 112, the same one as the polarization control element 108 is used, and the polarization direction of only the R light is rotated to generate R, G, B.
Has the function of aligning the polarization directions of. The polarizing plate 113 cuts out leakage light of the light originally cut by the PBS 109 out of the light from the polarization control element 112, and C.I. R. Improve. When the projection is configured with the above configuration, the brightness can be improved by about 1.5 times as compared with the conventional single plate field sequential system.

In this embodiment, the polarization control elements 108 and 112 for rotating the polarization of the R light are used, but the polarization direction of the B or G may be rotated and the P and S polarizations of the respective colors incident on the PBS 109 may be rotated. May be replaced. Further, in the present embodiment, white is separated into B, G and R, but any combination such as G, R and B is possible. In this case, it is only necessary to change the color of light rotated by the polarization control elements 108 and 112. Further, in the present embodiment, the polarizing plate and the polarization control element are arranged on both the light incident side and the light emitting side of the PBS 109, but the polarizing plate 113 and the polarization control element 112 on the light emitting side are arranged.
Is not always necessary.

[0079]

As described above, according to the present invention, by using a color filter for different colored light and a polarization control means for rotating only the polarization direction of light in a specific wavelength range, a reflective image display device can be obtained. , Two colors of R, G, and B can always be used, so that the brightness is dramatically improved without significantly increasing the size or the price, compared with the conventional method using a single plate type field sequential. be able to.

By adjusting the color light selection area of the rotary color filter, it is possible to adjust the white balance and improve the brightness of the screen incident light without degrading other performances.

Furthermore, two different rotary color filters are used.
By adjusting the color common to the colored lights to light with strong or weak spectral intensity of the light source, it is possible to adjust the white balance of the incident light on the screen without deteriorating other performances, similar to the adjustment of the above-mentioned feeling of colored light. Brightness can be increased. Further, by forming not only the above-mentioned two colored light regions but also a transparent region in the rotary color filter, the brightness at the time of white display can be further improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a projection type color image display device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a rotary color filter.

FIG. 3 is a spectral characteristic of the polarization control element used in the first embodiment.

FIG. 4 is an explanatory diagram of an optical system used for measuring a spectral characteristic of a polarization control element.

FIG. 5 is an explanatory diagram of a function of a polarization control element.

FIG. 6 is an explanatory diagram of another rotating color filter.

FIG. 7 is a schematic diagram of a projection type color image display device according to a second embodiment of the present invention.

FIG. 8 is an explanatory diagram of a rotating color filter used in the second embodiment.

FIG. 9 is a spectral characteristic diagram of a polarization control element that rotates only polarized light in the red wavelength range.

FIG. 10 is a schematic diagram of a projection type color image display device according to a third embodiment of the invention.

FIG. 11 is an explanatory diagram of a rotating color filter used in the third embodiment.

FIG. 12 is a spectral characteristic diagram of a polarization control element that rotates only polarized light in a green wavelength range.

FIG. 13 is a schematic diagram of a projection type color image display device according to a fourth embodiment of the present invention.

FIG. 14 is an explanatory diagram of a rotating color filter used in the fourth embodiment.

FIG. 15 is a schematic diagram of a projection type color image display device according to a fifth embodiment of the present invention.

FIG. 16 is an explanatory diagram of a rotating color filter used in the fifth embodiment.

FIG. 17 is a schematic diagram of another projection type color image display device according to the fifth embodiment.

FIG. 18 is an explanatory diagram of a pixel portion of a transmissive liquid crystal display element.

FIG. 19 is an explanatory diagram of a reflective liquid crystal display element.

FIG. 20 is an explanatory diagram of a three-plate type liquid crystal projection using a conventional reflective liquid crystal display element.

FIG. 21 is an explanatory diagram of a conventional rotary color filter.

[Explanation of symbols]

101 light source 102 elliptical mirror 103 rotating color filter 104 glass rod 105 illumination lens 106 field lens 107 polarizing plate 108 polarization control element 109 PBS 110-1, 110-2, 110-3 reflective liquid crystal element 111 projection lens 112 polarization control element 113 Polarizing plates 701-1 and 701-2 Rotation color filter 702 Polarization control element 703 Polarization control elements 1001-1 and 1001-2 Rotation color filter 1002 Polarization control element 1003 Polarization control element 1301 Rotation color filter 1501 TFT 1502 Black matrix 1503 Gate bus Line 1504 Source bus line 1601 Reflecting electrode 1901 Rotating color filter 1902 Dichroic mirror

─────────────────────────────────────────────────── ─── Continued Front Page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03B 33/12 G03B 21/00-21/30 G02F 1/13 G02F 1/1335-1/13363 G02B 27 / 18

Claims (10)

(57) [Claims] 1. A light source and two colors of light of three primary colors of red, green and blue contained in the light source.
The color lights of two different groups including
Color separation consisting of a rotating color filter with the function of selecting
Common to the replacement means and the colored lights of the two different groups
Converts the polarization direction of light of color or other two colors
By providing the first polarization control means having a function,
Te, red from the light source, green, divided light of the three primary colors of blue to a group of two color lights, with sequentially switched by time division color light of the two groups, the red from the light source, green, 3 blue Of the primary color light, an illuminating means having a function of irradiating two colors with different polarization directions from the other one color, a light separating means for separating the light from the light source according to the polarization direction, and the light separating means An image display device comprising: a plurality of reflective image display elements that modulate the separated light; and a projection unit that projects the light modulated by the reflective image display element. 2. An image according to claim 1, wherein the second polarization control unit having the same function as the first polarization control unit to the projection unit side of said light separating means is arranged Display device. Wherein the first according to claim 1, wherein the image polarization selecting device is characterized in that it is arranged to transmit only one direction of polarization directions on the optical path of the light incident side of the polarization control means Display device. 4. The image according to claim 2 or 3, wherein a polarization selection element that transmits only one polarization direction is arranged on the optical path on the light exit side of the second polarization control means. Display device. 5. The two reflective image display elements are arranged, one corresponding to one color of the light of the three primary colors, and the other corresponding to the remaining two colors. the image display apparatus according to any one of claims 1 to 4, characterized. 6. The selection time of the color light including the light having the weaker spectral intensity of the light source among the lights of the two colors other than the color common to the two different color lights selected by the color switching means is the other color light. 6. The image display device according to claim 1 , wherein the image display device is longer than the selection time. 7. The green component is included in only one of the two different colored lights selected by the color switching means, and the selection time of the colored light containing green is longer than the selection time of the other colored light. The image display device according to claim 1 , wherein the image display device is provided. 8. The color common to the two different colored lights is:
The image display device according to any one of claims 1 to 5 , wherein the corresponding light source is light having the weakest spectral intensity. 9. The color common to the two different colored lights is
The image display device according to claim 1 , wherein the image display device is green. Wherein said color switching means, the red, green, image display apparatus according to any one of claims 1 to 9, characterized in that it has an area that transmits all three primary colors of blue.