JPH07306405A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To brightly expand and display an image on a screen in a high luminance state by providing polarizing beam splitters on a rear side and a front surface side of a transmission type liquid crystal panel having no polarizing plate when the image data are expanded and displayed using the transmission type liquid crystal panel. CONSTITUTION:In a liquid crystal display device 1A, the polarizing beam splitters 3, 4 are arranged respectively on the rear 2a side and the front surface 2b side of the transmission type liquid crystal panel 2 having no polarizing plate for expanding and displaying the image data displayed on the front surface 2b of the transmission type liquid crystal panel 2. Further, after an illuminating light from a lamp light source 5 irradiates the polarizing beam splitter 3, and is polarization converted to a P polarized light, it is made incident on the transmission type liquid crystal panel 2, and the light modulated by the transmission type liquid crystal panel 2 is emitted to a projection lens 6 in the state where only the P polarized light is density modulated by the polarizing beam splitter 4 on an emission side, and the image data displayed on the transmission type liquid crystal panel 2 are expanded and displayed on the screen 7 in the high luminance state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention illuminates the rear surface of a transmissive liquid crystal panel with illumination light from a lamp light source, and enlarges image data displayed on the front surface of the transmissive liquid crystal panel on a screen by a projection lens. In this case, the present invention relates to a liquid crystal display device capable of brightly enlarging and displaying an image on a screen in a high brightness state by providing polarizing beam splitters on the back side and front side of a transmissive liquid crystal panel having no polarizing plate.

[0002]

2. Description of the Related Art Recently, the diversification of image information and the improvement of image quality have progressed, and high-quality image data represented by the high-definition broadcasting standard and the SVGA standard of computer graphics has increased. Various display devices for enlarged display have been actively proposed.

As an example of this type of display device, a liquid crystal display device for enlarging and displaying image data using a liquid crystal panel which is small, lightweight and suitable for mass production is widely used.

FIG. 9 is a diagram for explaining an example of a liquid crystal display device in the conventional example, and FIG. 10 is a diagram for explaining another example of the liquid crystal display device in the conventional example.

In the liquid crystal display device 100 of the example shown in FIG. 9, the illumination light from the lamp light source 104 is twisted.
When the back surface 101a of the transmissive liquid crystal panel 101 using nematic (TN) liquid crystal or the like is irradiated and the image data displayed on the front surface 101b of the transmissive liquid crystal panel 101 is enlarged and displayed on the screen 106 by the projection lens 105, Polarizing plates 102 and 103 are arranged on the rear surface 101a side and the front surface 101b side of the transmissive liquid crystal panel 101,
The polarizing plate 102 on the incident side receives the illumination light from the lamp light source 104.
When illuminated onto the polarizing plate 102
The liquid crystal panel 10 becomes a linearly polarized light by being polarized by
The linearly polarized light polarized by the polarizing plate 102 is transmitted through each pixel or blocked by each pixel depending on the electric field state of each pixel in 3 so that the light modulated by the transmissive liquid crystal panel 103 is emitted. Since the linearly polarized light is emitted from the polarizing plate 103 to the projection lens 105, the liquid crystal panel 103
The image data displayed on the screen is enlarged and displayed on the screen 106.

Next, in another example of the liquid crystal display device 200 shown in FIG. 10, as disclosed in US Pat. No. 5,115,305 (registration date 1992.5.19), RGB is used.
Three-color transmission type liquid crystal panels 201 to 203 for (red green blue)
Are arranged at the positions shown without using a polarizing plate.

Further, the illumination light from the lamp light source 204 is
The dichroic mirrors 205 to 207 are separated into three colors of RGB (red, green and blue), and the separated lights of the three colors correspond to the corresponding RGB.
(Red, green, and blue) are incident on the three-color transmissive liquid crystal panels 201 to 203, respectively. Further, a polarization beam splitter 208 is installed on the exit side of the transmissive liquid crystal panel 201 for red light, and a green beam on the exit side of the transmissive liquid crystal panel 202 for green light and the transmissive liquid crystal panel 203 for blue light. A polarization beam splitter 209 for blue is installed, and a polarization beam splitter 210 for synthesizing three colors is used for synthesizing the color-separated light of the three colors.
It is installed on the emission side of 8,209.

At this time, the above-mentioned polarization beam splitter 2
08 to 210 are formed in a rectangular parallelepiped shape using a glass material having good heat resistance, and dielectric multilayer films 208a to 210a are formed inside the glass material along a diagonal line. Here, the polarization beam splitters 208 to 210 are used.
The dielectric multilayer films 208a to 210a are formed by filming so that the incident angle of is set to about 45 °. The incident angle of the polarization beam splitters 208 to 210 means an angle formed by the optical axis at the time of incident light and the normal vector of the dielectric multilayer films 208a to 210a.

Also, these polarization beam splitters 20
Of the 8 to 210, the polarization beam splitters 208, 20
9 is an indefinite polarized light that is incident on one surface and is an S polarized light,
The polarized light is separated by 50%: 50%, and at this time, it has a function of separating light into S-polarized light and P-polarized light with high light transmittance without absorption of light. On the other hand, the polarization beam splitter 21
0 has a function of color-synthesizing polarized lights separated into three colors.

Further, between the transmission type liquid crystal panel 203 and the polarization beam splitter 209, and between the polarization beam splitter 209 and the polarization beam splitter 210, λ
/ 2 plates 211 and 212 are installed, respectively. On this occasion,
The λ / 2 plates 211 and 212 described above are formed with a phase angle of 90 °, and have a function of converting S-polarized light into P-polarized light or P-polarized light into S-polarized light.

Then, a transmissive liquid crystal panel 20 for red light is used.
The red light that has passed through 1 is reflected by the polarization beam splitter 208, and is polarized by the polarization beam splitter 210 for three-color synthesis.
Of the green light, which has passed through the transmission type liquid crystal panel 202 for green light, is reflected by the polarization beam splitter 209, and then enters the polarization beam splitter 210 for three-color synthesis from the λ / 2 plate 212. On the other hand, the blue light that has passed through the transmissive liquid crystal panel 203 for blue light passes through the λ / 2 plate 211 and then goes straight through the polarization beam splitter 209 to enter the polarization beam splitter 210 for three-color synthesis. Here, RGB transmissive liquid crystal panels 201 to 2
The image data displayed in 03 is color-combined into one color image data by the polarization beam splitter 210 for three-color composition, and then enlarged and displayed as a color image on the screen not shown by the projection lens 213. Since the transmittance of light is not attenuated even though it passes through the polarization beam splitter 208 for use with the light, the polarization beam splitter 209 for both green and blue colors, and the polarization beam splitter 210 for combining three colors, the enlarged display of the color The image is brightly and enlargedly displayed in the high-luminance state.

[0012]

In the liquid crystal display device 100 of the example shown in FIG. 9, the transmissive liquid crystal panel 1 is used.
01 is capable of enlarging and displaying the image data displayed on the front surface 101b, but is on the rear surface 101a of the transmissive liquid crystal panel 101.
And the polarizing plates 102 and 103 arranged on the front surface 101b side
Absorbs a part of the light that has been transmitted inside, so that the light transmittance is generally as low as about 30% to 40%. Therefore, the image enlarged and displayed on the screen 106 is naturally displayed dark. In addition, the polarizing plate 102,
Since 103 is generally formed by impregnating a polymer film with iodine, dye, etc. dissolved in polyvinyl alcohol or the like, the heat resistance is poor, and the temperature rises due to light absorption, or the lamp light source 104. The polarization conversion performance also deteriorates depending on the temperature of the illumination light from the polarizing plate 102.
Since it cannot illuminate the screen 106,
There is a problem that the image enlarged and displayed above is displayed darkly.

Further, in the liquid crystal display device 200 of another example shown in FIG. 10, since no polarizing plate is used, the image data of three colors displayed on the RGB transmissive liquid crystal panels 201 to 203 are color-synthesized. Although a single color image can be enlarged and displayed brightly, the polarization beam splitter 209 for both green and blue and the polarization beam splitter 210 for three-color synthesis used here are good polarization conversions for a plurality of colors at the same time. Need performance. In order to achieve this, it is necessary to manufacture the polarization beam splitters 209 and 210 having a wide wavelength range corresponding to a plurality of colors, but it is technically very difficult to manufacture the polarization beam splitters 209 and 210 having a wide wavelength range. However, there is a problem in that there is a problem in the contrast of the enlarged and displayed color image.

[0014]

The present invention has been made in view of the above problems, and the first invention is to illuminate the back surface of one transmissive liquid crystal panel with illumination light from a light source and to transmit the transmissive liquid crystal panel. In a liquid crystal display device in which image data displayed on the front surface of a liquid crystal panel is enlarged and displayed on a screen by a projection lens, polarizing beam splitters are provided on the rear and front sides of a transmissive liquid crystal panel having no polarizing plate. Is a liquid crystal display device.

According to a second aspect of the invention, the illumination light from the light source is separated into three colors of RGB by the three-color separating member, and the separated lights of the three colors are applied to the back surfaces of the transmissive liquid crystal panels corresponding to the respective colors. Then, the image data corresponding to each color displayed on the front surface of the transmissive liquid crystal panel of each color is color-synthesized by the three-color synthesis member, and one color image data emitted from the three-color synthesis member is projected by the projection lens. In the liquid crystal display device for enlarging and displaying on the screen by the above, a polarizing beam splitter is provided independently for each color on the back side and the front side of the transmissive liquid crystal panel of each color having no polarizing plate. It is a display device.

A third invention is the liquid crystal display device according to the second invention, wherein the optical path lengths from the light source to the transmissive liquid crystal panels of the respective colors are set substantially equal to each other, and the transmissive liquid crystals of the respective colors are set. In the liquid crystal display device, each optical path length from the panel to the projection lens is set to be substantially equal.

According to a fourth aspect of the present invention, in the liquid crystal display device of the second aspect, the polarization beam splitters independently provided for each color have wavelength selectivity corresponding to the transmission type liquid crystal panel of each color. A liquid crystal display device characterized by being formed by holding it.

A fifth invention is the liquid crystal display device according to the second invention, wherein between the light source and the three-color separation member,
Alternatively, in the liquid crystal display device, a polarization beam splitter is provided on at least one of the three-color combining member and the projection lens.

A sixth aspect of the invention is the liquid crystal display device of the second aspect, wherein the three-color separating member is a cross-type plate-shaped filter, and the three-color synthesizing member is a cross-type prism-shaped filter. And a liquid crystal display device characterized by the above.

Further, a seventh invention is the first invention and the second invention.
In the liquid crystal display device according to the invention, a phase plate is provided on either the back side or the front side of the transmissive liquid crystal panel.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a liquid crystal display device according to the present invention will be described below in detail in the order of <first embodiment>, <second embodiment>, <third embodiment> with reference to FIGS. Explained.

<First Embodiment> FIG. 1 shows a first embodiment of the present invention.
FIG. 2 is a perspective view showing a liquid crystal display device of an embodiment, and FIG. 2 and FIG. 3 are perspective views showing a liquid crystal display device of a first embodiment according to the present invention, which is partially modified.

In the liquid crystal display device 1A of the first embodiment according to the present invention shown in FIG. 1A, illumination light from a light source (hereinafter referred to as a lamp light source) 5 is used as a twisted nematic (TN) liquid crystal or the like. When the back surface 2a of one (single plate type) transmissive liquid crystal panel 2 is irradiated with the image data displayed on the front surface 2b of the transmissive liquid crystal panel 2 by the projection lens 6 on the screen 7 in an enlarged manner. Polarizing beam splitters 3 and 4 are arranged on the rear surface 2a side and the front surface 2b side of the transmissive liquid crystal panel 2 having no polarizing plate, respectively. These polarizing beam splitters 3 and 4 are provided in place of the polarizing plates provided on the back side and the front side of the transmissive liquid crystal panel as described in the conventional liquid crystal display device.

Further, these polarization beam splitters 3,
Similarly to the liquid crystal display device of another example in the related art, 4 is formed in a rectangular parallelepiped shape using a glass material having good heat resistance, and the dielectric multilayer film is formed inside the glass material along a diagonal line. 3a and 4a are formed by filming, respectively. In this embodiment, the dielectric multilayer films 3a and 4a are illustrated so that the incident angles of the polarization beam splitters 3 and 4 are approximately 45 °. The incident angle of the polarization beam splitters 3 and 4 means the angle formed by the optical axis at the time of incident light and the normal vector of the dielectric multilayer films 3a and 4a. However, the incident angles of the polarization beam splitters 3 and 4 depend on the relationship such as the refractive index of the glass material and the S-polarized light and P-polarized light described below.
It affects the polarization conversion performance (separation performance) of each polarized light, and is not necessarily limited to about 45 °, and the polarization beam is optimized so that the polarization conversion performance is optimized based on the refractive index of the glass material. The incident angle of the splitters 3 and 4 is 35
In some cases, the angle may be set to about 65 ° to 65 °. Incidentally, the incident angle of the polarization beam splitter used in the second and third embodiments described later may be set to about 35 ° to 65 ° in the same manner as above. In addition, these polarization beam splitters 3 and 4 separate indefinite polarized lights or polarized lights incident on one surface into S-polarized lights and P-polarized lights by 50%: 50% respectively.
At this time, it has a function of separating light into S-polarized light and P-polarized light with good light transmittance without absorption of light.

Therefore, by arranging the polarization beam splitters 3 and 4 on the rear surface 2a side and the front surface 2b side of the transmissive liquid crystal panel 2 having no polarizing plate as described above, it is possible to reduce the light intensity compared to the case where the polarizing plate is provided. Of the polarization beam splitter 3, which is made of a glass material.
No. 4 maintained good heat resistance.

Further, when the illumination light from the lamp light source 5 is applied to the surface 3b of the polarization beam splitter 3 provided on the incident side, it is incident on the surface 3b of the polarization beam splitter 3 substantially parallel to the back surface 2a of the transmissive liquid crystal panel 2. The illumination light, which is an indefinite polarized light, is polarization-converted into P-polarized light in the direction of the arrow and goes straight through the dielectric multilayer film 3a of the polarization beam splitter 3 as it is.
It enters the transmissive liquid crystal panel 2. Here, depending on the electric field state of each pixel in the transmissive liquid crystal panel 2, P-polarized light polarized by the polarization beam splitter 3 passes through each pixel or is blocked by each pixel, so that the transmissive liquid crystal panel 2
The light modulated by is transmitted from the surface 4b of the polarization beam splitter 4 which is substantially parallel to the front surface 2b of the transmissive liquid crystal panel 2 in the direction of arrow P.
Since only the polarized light is emitted to the projection lens 6 in a density-modulated state, the image data displayed on the front surface 2b of the transmissive liquid crystal panel 2 can be brightly and enlargedly displayed on the screen 7 in a high-luminance state.

Therefore, in the liquid crystal display device 1A of the first embodiment configured as described above, the polarization beam splitters 3 and 4 are provided on the rear surface 2a side and the front surface 2b side of the transmissive liquid crystal panel 2 having no polarizing plate. As a result, since there is no absorption of light during polarization conversion by the polarization beam splitters 3 and 4, the light transmittance is not attenuated at all, and the image displayed on the screen 7 in an enlarged manner is obtained as a bright screen in a high brightness state. Since the polarization beam splitter 3 on the incident side has good heat resistance, it is possible to irradiate the polarization beam splitter 3 with strong light as the illumination light from the lamp light source 5, which also makes the image enlarged and displayed on the screen 7 brighter. it can. Further, each of the constituent members 2 to 4 in the liquid crystal display device 1A of the first embodiment has a high light utilization rate and the projection lens 6
It is possible to provide the liquid crystal display device 1A that is low in cost including the above and has a high degree of freedom in design.

In the above-described liquid crystal display device 1A, one (single plate type) transmissive liquid crystal panel 2 in which the optical path form from the lamp light source 5 to the screen 7 is formed in a substantially straight line, and mono-color or three colors are combined. 2 is used, a case in which an optical path configuration different from that of the liquid crystal display device 1A is adopted will be described with reference to FIGS. 2 and 3.

In the liquid crystal display devices 1B and 1C of the modified example of the first embodiment shown in FIGS. 2 and 3, the polarized light provided on the rear surface 2a side and the front surface 2a side of the transmissive liquid crystal panel 2 having no polarizing plate. Dielectric multilayer film 3 of beam splitters 3 and 4
The positions of the lamp light source 5 on the incident side and the position of the projection lens 6 on the emitting side are determined depending on how the positions of a and 4a face the rear surface 2a side and the front surface 2a side of the transmissive liquid crystal panel 2. Is set and the optical path can be changed, and along with this, P by the polarization beam splitters 3 and 4 can be changed.
The polarization conversion states of polarized light and S polarized light can be appropriately set.

That is, in the liquid crystal display device 1B of the modified example of the first embodiment shown in FIG. 2, the lamp light source 5 is incident on the polarization beam splitter 3 from the front left lateral direction on the rear surface 2a side of the transmissive liquid crystal panel 2. Then, the S-polarized light is reflected by the dielectric multilayer film 3a of the polarization beam splitter 3, and then the light passing through the transmissive liquid crystal panel 2 is polarized by the polarization beam splitter 4.
It is reflected by the dielectric multilayer film 4a and is emitted in the S-polarized state to the projection lens 6 installed in the front right lateral direction on the front surface 2b side of the transmissive liquid crystal panel 2.

Further, in the liquid crystal display device 1C of the modified example of the first embodiment shown in FIG. 3, the lamp light source 5 is incident on the polarization beam splitter 3 from the lower left on the rear surface 2a side of the transmissive liquid crystal panel 2. Polarization beam splitter 3 for S-polarized light
Of the dielectric multi-layered film 3a, and then the light that has passed through the transmissive liquid crystal panel 2 is reflected by the dielectric multi-layered film 4a of the polarization beam splitter 4 to form the S-polarized state in the front face 2b side of the transmissive liquid crystal panel 2. It is emitted to the projection lens 6 installed in the front right lateral direction.

Also in the liquid crystal display devices 1B and 1C of the modified example of the first embodiment, the same effect as the above-mentioned liquid crystal display device 1A can be obtained by the polarization beam splitters 3 and 4, and here, the liquid crystal display device 1A is Since different optical path configurations can be set as appropriate, the installation conditions of the liquid crystal display devices 1B and 1C can be appropriately dealt with.

<Second Embodiment> FIG. 4 shows a second embodiment of the present invention.
It is the perspective view which showed the liquid crystal display device of the Example.

The liquid crystal display device 2 of the second embodiment shown in FIG.
0 is the liquid crystal display device 1A (~) of the first embodiment described above.
1C) is the same as the configuration of FIG. 1C except for a part. Here, for convenience of explanation, the same reference numerals are given to the above-mentioned constituent members, and the above-mentioned constituent members are necessary. A description will be given accordingly, and a new reference numeral will be given to a component different from the conventional one.

The liquid crystal display device 2 of the second embodiment shown in FIG.
In No. 0, in the configuration of the liquid crystal display device 1A of the first embodiment, the λ / 2 plate 21 is inserted on the rear surface 2a side of the transmissive liquid crystal panel 2 having no polarizing plate. In this example,
A λ / 2 plate 21 is inserted between the surface 3 c of the polarization beam splitter 3 and the back surface 2 a of the transmissive liquid crystal panel 2. At this time, the λ / 2 plate 21 is a special type of phase plate having a phase angle of 90 ° as described in the liquid crystal display device of another example of the related art among the phase plates formed with an arbitrary phase angle. The λ / 2 plate 21 has a function of converting the S polarized light into the P polarized light or the P polarized light into the S polarized light.

Therefore, when the illumination light from the lamp light source 5 is applied to the surface 3b of the polarization beam splitter 3 provided on the incident side, it is incident on the surface 3b of the polarization beam splitter 3 substantially parallel to the back surface 2a of the transmissive liquid crystal panel 2. The illumination light, which is indefinite polarized light, is polarization-converted into P polarized light in the direction of the arrow and goes straight through the dielectric multilayer film 3a as it is, and from the surface 3c facing the surface 3b of the polarization beam splitter 3 in the P polarized light state λ. / 2 plate 2
It is incident on 1. Here, the λ / 2 plate 21 emits P-polarized light,
It is converted into S-polarized light in the direction of the arrow, and the S-polarized light is incident on the transmissive liquid crystal panel 2.

The electric field state of each pixel in the transmissive liquid crystal panel 2 can be generally classified into a normally black type TN cell type and a normally white type TN cell type, that is, the former normally type. The black type TN cell type is a type in which light is absorbed and displayed in black when no voltage is applied, while the latter normally white type T type cell is used.
The N-cell form is a form in which light is transmitted and displayed in white when no voltage is applied.

Therefore, the transmissive liquid crystal panel 2 used
Is normally black type TN cell type or normally white type TN cell type.
By selectively inserting the two plates 21, it is possible to set the image display to either normally black or normally white.

In the embodiment, the λ / 2 plate 21 is inserted on the incident side (rear surface 2a side) of the transmissive liquid crystal panel 2, but the present invention is not limited to this. You may insert in (the front surface 2b side).

When it is desired to display intermediate colors, a phase plate (not shown) formed by replacing the λ / 2 plate 21 having a phase angle of 90 ° with an arbitrary phase angle is used on the incident side of the transmissive liquid crystal panel 2. Alternatively, it can be set to either normally black or normally white by inserting it into either one of the emitting sides.

Further, the phase plate (not shown) formed with an arbitrary phase angle can be applied to the liquid crystal display device of the third embodiment described later.

<Third Embodiment> FIG. 5 shows a third embodiment of the present invention.
FIG. 6 is a perspective view showing the liquid crystal display device of the embodiment, and FIG. 6 shows a state in which the liquid crystal display device of the third embodiment is shown in plan view, and (A) shows a lamp light source and a polarization beam splitter on the incident side. 8B is a view showing a polarization beam splitter and a projection lens on the exit side, FIG. 7 is a perspective view showing a partially modified liquid crystal display device according to a third embodiment of the present invention, and FIG.
FIG. 8 is a perspective view showing the three-color separating member and the three-color combining member shown in FIGS. 5 to 7, (A) showing a cross prism filter, and (B) showing a cross plate filter. It is the figure shown.

The liquid crystal display device 30A of the third embodiment according to the present invention shown in FIG.
It is a single-panel type with color composition and uses the technical idea of arranging polarizing beam splitters on the back side and front side of a transmissive liquid crystal panel that does not have a polarizing plate. The light source (hereinafter referred to as lamp light source) is applied. The illumination light from 42 is separated into three colors 40
Are separated into three colors of RGB (red, green, blue) by irradiating the rear surfaces 31a to 33a of the transmissive liquid crystal panels 31 to 33 corresponding to the respective colors, and the transmissive liquid crystal panels 31 to 31 of the respective colors are separated. Image data corresponding to the respective colors displayed on the front surfaces 31b to 33b of 33 are color-synthesized by the three-color synthesis member 41, and one color image data emitted from the three-color synthesis member 41 is screened by the projection lens 43 (Fig. (Not shown) does not have a polarizing plate, and R
Transmissive liquid crystal panel 31 corresponding to three colors of GB (red green blue)
~ 33 rear surface 31a-33a side and front surface 31b-33b
On the side, three sets of polarization beam splitters (34, 35),
(36, 37) and (38, 39) are arranged independently for each color so that a color image can be displayed brightly and enlarged in a high brightness state.

In FIG. 5, the transmissive liquid crystal panel 31 for red light, the transmissive liquid crystal panel 32 for green light, and the transmissive liquid crystal panel 33 for blue light do not have a polarizing plate, respectively, and each has three plates. We have prepared these transmissive LCD panels 3
The polarizing beam splitters 34 and 35 for red light and the polarizing beam splitter 3 for green light are provided on the back surfaces 31a to 33a and the front surfaces 31b to 33b, which are located above and below 1-3, respectively.
6,37 and polarization beam splitters 38,3 for blue light
Three sets of 9 and 9 are provided independently for each color. On this occasion,
The polarization beam splitters 34 and 35 for red light, the polarization beam splitters 36 and 37 for green light, and the polarization beam splitters 38 and 39 for blue light are formed in a rectangular parallelepiped shape using a glass material having good heat resistance. In addition, a dielectric multilayer film having wavelength selectivity corresponding to three colors of RGB is formed by film formation. Further, these polarization beam splitters 34 to 39 separate indefinite polarized lights or polarized lights incident on one surface into S-polarized lights and P-polarized lights by 50%: 50% respectively, and at this time, absorb light. It has a function of separating light into S-polarized light and P-polarized light with good light transmittance.

The polarization beam splitter 3 on the incident side
4, 36, and 38 are the three surfaces 40b of the three-color separation member 40 installed in the rectangular volume at the upper center of the figure as described later.
It is arranged so as to surround along the outside of ~ 40d, while, on the other hand, the polarization beam splitters 35, 37,
Reference numeral 39 denotes a three-color combining member 41 installed in the rectangular volume at the lower center of the drawing and facing below the three-color separating member 40.
Are arranged so as to be surrounded along the outer sides of the three surfaces (41b to 41d ... Not shown). Therefore, the three-color transmissive liquid crystal panels 31 to 33 are arranged along the outer side of the space formed between the three-color separation member 40 and the three-color separation member 41 and the three surfaces 40 b to 40 of the three-color separation member 40. 3 of the three-color composite member 41
It is arranged so as to correspond to the surfaces (41b to 41d ... Not shown).

Illumination light, which is an indefinite polarized light from the lamp light source 42, is incident on the surface 40 of the three-color separation member 40.
It is incident on a.

Here, the structure of the three-color separation member 40 (40A or 40B) is a cross-type prism-shaped filter as shown in an enlarged view in FIG. 8A, or the structure shown in FIG. 8B. A cross-type plate-shaped filter as shown in the enlarged view is used. That is, it is composed of a cross-type prism-shaped filter as shown in the enlarged view of FIG.
The color separation member 40A is formed in a rectangular parallelepiped shape using a glass material having high heat resistance, and a dielectric multilayer film is formed in a cross shape along the diagonal line inside the glass material. Also, a cross-type prism-shaped three-color separation member 40A
Has good three-color separation performance because cross-shaped intersections are well formed without discontinuities, but the cost tends to be high during manufacturing. On the other hand, the three-color separation member 40B composed of a cross-shaped plate-shaped filter as shown in an enlarged view in FIG. 8B has a plurality of transparent resin plates having good heat resistance and the same dielectric multilayer film. After the respective films are applied, the plurality of transparent resin plates and the like are abutted in a cross shape to be assembled and formed. Further, the cross-type plate-shaped three-color separation member 40B is
When a plurality of transparent resin plates are crossed with each other, the cross-shaped intersections may be cut, so that the three-color separation performance is slightly inferior, but since the plate material is used, the cost tends to be low.

At this time, since the illumination light, which is an indefinite polarized light from the lamp light source 42, is incident on the three-color separation member 40 from all directions, a low-cost type liquid crystal display device 30A which does not require the three-color separation performance so much. 8B, it is better to use an inexpensive cross-type plate-shaped three-color separation member 40B as shown in an enlarged view in FIG. In order to satisfy the above requirement, a cross-type prism-shaped three-color separation member 40A with good performance as shown in an enlarged view in FIG. 8A may be used.

Therefore, the illumination light incident on the surface 40a of the three-color separation member 40 is converted into RGB (red, green, blue) by the three-color separation member 40 (40A or 40B) as shown in FIG. 7A. The surface 40b of the three-color separation member 40 is separated into colors.
From the surface, green light from the surface 40c, and blue light from the surface 40d are emitted to the surfaces 34a, 36a, 38a of the polarization beam splitters 34, 36, 38, respectively.

Returning to FIG. 5, after that, the separated lights of the three colors respectively entering the polarization beam splitters 34, 36 and 38 are
The light is reflected by the dielectric multilayer films in the polarization beam splitters 34, 36 and 38 and is not incident on the transmissive liquid crystal panels 31 to 33 below without attenuating the transmittance of the light, and the transmissive liquid crystal panel 31 for each color. The decomposed lights modulated by ˜33 enter the polarization beam splitters 35, 37, 39 disposed below and are reflected by the dielectric multilayer film and are not attenuated in light transmittance. , 37, 39
From the surfaces 35a, (37a), 39a of the three-color composite member 41
It is emitted toward.

The structural form of the above-mentioned three-color synthesizing member 41 is the same as the structural form of the above-mentioned three-color synthesizing member 40, and this three-color synthesizing member 41 is also shown enlarged in FIG. 8 (A). By adopting such a cross-type prism-shaped filter as described above or a cross-type plate-shaped filter as shown in an enlarged view in FIG. 8 (B), the decomposed light of the three separated colors is color-synthesized. There is.

In this case, when the low-cost type liquid crystal display device 30A which does not require the three-color synthesis performance is used, an inexpensive cross type plate-shaped three colors as shown in an enlarged view in FIG. 8B is used. It is better to use the synthesizing member 41B. On the other hand, when three-color synthesizing performance is required for business use, etc., a cross-type prism-shaped 3 having good performance as shown in an enlarged view in FIG. The color synthesis member 41A may be used.

As described above, when the illumination light from the lamp light source 42, which is an indefinite polarized light, is decomposed into three colors, a low cost type liquid crystal display device 30A that does not require the three-color separation performance is used as a cross-shaped plate. 3 color separation member 40B
Even if it is configured by using, if the cross-prism-shaped three-color combining member 41A is used during the three-color combination, the S-polarized light or the P-polarized light separated into the three colors that are not indefinite polarized light is color-combined. The color image can be enlarged and displayed with high image quality and the liquid crystal display device 30A can be provided inexpensively without being affected by the deterioration of the three-color separation performance due to the use of the cross-type plate-shaped three-color separation member 40B.

Therefore, the polarization beam splitter 3 on the output side
The separated lights of the three colors incident on the three-color combining member 41 from the surfaces 35a, 37a, 39a of the 5, 37, 39 are the three-color combining members 41 (41A or 41A) as shown in FIG. 7B.
The combined light that is color-combined by B) and combined into the original three colors of RGB (red, green, and blue) is emitted toward the projection lens 43 from the surface 41 a that is the emission surface of the three-color combining member 41.

Returning to FIG. 5 again, at this time, as shown in the drawing, the transmission type liquid crystal panels 31 to 33 and the polarization beam splitters (34, 35), (36, 37), (38,
39) is three-dimensionally stacked in the same state,
Three color transmissive liquid crystal panels 31 to 33 from the lamp light source 42
The optical path lengths of the respective colors from the three color transmissive liquid crystal panels 31 to 33 to the projection lens 43 are set to be substantially equal to each other. The optical path length of each color is almost constant,
As a result, the optical path state for each color can be formed in a stable state with substantially the same conditions, and the optical path length for each color can be set short, so that the liquid crystal display device 30A of the third embodiment can be miniaturized. Becomes

Therefore, in the liquid crystal display device 30A of the third embodiment configured as described above, the rear surface of the transmissive liquid crystal panels 31 to 33 without the polarizing plate and corresponding to the three colors of RGB (red, green and blue). 31a-33a side and front surface 31b-
On the 33b side, three sets of polarization beam splitters (34, 3
5), (36, 37), (38, 39) are provided independently for each color, so that three sets of polarization beam splitters (34, 35), (36, 37), (38, 39) are provided.
Since the light transmittance is not attenuated at all when there is no light absorption at the time of polarization conversion by, the color image enlarged and displayed on the screen (not shown) is obtained as a bright screen in a high brightness state. In addition, three sets of polarization beam splitters (34, 35), (36, 3) provided independently for each color are provided.
7) and (38, 39) are three-color transmissive liquid crystal panels 31.
The color images to be displayed in enlargement have a high contrast ratio and can be realized as a liquid crystal display device 30A with high image quality. Further, since the polarization beam splitters 34, 36, 38 on the incident side have good heat resistance, it is possible to irradiate the polarization beam splitters 34, 36, 38 with strong light as the illumination light from the lamp light source 42, which also causes an enlarged display. The color image is displayed brighter. Further, each of the constituent members 31 to 41 in the liquid crystal display device 30A of the third embodiment has a high light utilization rate and is low in cost including the projection lens 43,
Moreover, the liquid crystal display device 30A having a high degree of freedom in design can be provided.

In the structure of the liquid crystal display device 30A, the three-color separating member 40 (40A or 40B) and the three-color synthesizing member 41 (41A or 41B) are used in three-color separating and three-color separating functions. Although different in composition, the structural forms are the same in both of them 40 and 41 as described above, so it is clear that the lamp light source 42 and the projection lens 43 can be installed above and below, respectively.

Next, a liquid crystal display device 30B of a modification obtained by partially modifying the liquid crystal display device 30A of the third embodiment will be briefly described with reference to FIG.

In the liquid crystal display device 30B of the modification of the third embodiment shown in FIG. 7, a polarization beam splitter 44 is provided between the lamp light source 42 and the surface 40a of the three-color separation member 40.
Is inserted, and also between the surface 41a of the three-color synthesizing member 4 and the projection lens 43, the polarization beam splitter 45
The configuration is different from that of the liquid crystal display device 30A of the third embodiment described above in that is inserted.

The polarization beam splitter 4 additionally configured as described above.
Nos. 4 and 45 have a function of further improving the contrast ratio of the enlarged and displayed color image, and contribute to the performance improvement of the liquid crystal display device 30B of the modified example.

In the embodiment, the three color separation member 40 side,
The polarization beam splitter 44, on the three-color combining member 41 side,
However, the present invention is not limited to this, and the polarization beam splitter (at least one of the lamp light source 42 and the three-color separation member 40, or at least one of the three-color separation member 41 and the projection lens 43 is provided. By providing 44) and (45), it is possible to further improve the contrast ratio of the enlarged and displayed color image.

[0062]

In the liquid crystal display device according to the present invention described in detail above, according to the first aspect, the polarizing beam splitters are provided on the back side and the front side of the transmission type liquid crystal panel having no polarizing plate. Since there is no absorption of light during polarization conversion by the polarization beam splitter, the light transmittance is not attenuated at all, so the image is enlarged and displayed on the screen as a bright screen with high brightness, and the polarization beam splitter on the incident side is used. Has good heat resistance, so that strong light can be emitted from the light source to the polarization beam splitter, and the image enlarged and displayed on the screen can be displayed brighter. Further, each of the constituent members in the liquid crystal display device according to the first aspect can be provided as a liquid crystal display device having a high light utilization rate, a low cost including the projection lens, and a high degree of freedom in design.

Further, according to the second aspect, a polarizing beam splitter is provided for each color on the back side and the front side of the transmissive liquid crystal panel which does not have a polarizing plate and which corresponds to three colors of RGB (red, green and blue). By providing them independently, the light transmittance is not attenuated at all when there is no light absorption during polarization conversion by the polarization beam splitter, so the enlarged color image on the screen is displayed as a bright screen with high brightness. Since the polarization beam splitter on the incident side has good heat resistance, the polarization beam splitter can be irradiated with strong light as the illumination light from the light source, so that the color image enlarged and displayed can be displayed brighter. Further, each constituent member in the liquid crystal display device according to the second aspect can be provided as a liquid crystal display device having a high light utilization rate, a low cost including a projection lens, and a high degree of freedom in design.

According to a third aspect of the present invention, in the liquid crystal display device according to the second aspect, the optical path lengths from the light source to the transmissive liquid crystal panels of the respective colors are set substantially equal to each other, and the transmissive liquid crystal panel of the respective colors is set. By setting the optical path length from the to the projection lens substantially equal, the optical path length of each color from the light source to the projection lens becomes substantially constant, as a result, the optical path state for each color can be formed in a stable state of substantially the same condition, In addition, since the optical path length of each color can be set short, the liquid crystal display device can be downsized.

According to a fourth aspect, in the liquid crystal display device according to the second aspect, the polarization beam splitters provided independently for each color have wavelength selectivity corresponding to the transmission type liquid crystal panel of each color. Because they are formed by holding each, the enlarged color image has a high contrast ratio,
It can be realized as a high-quality liquid crystal display device.

According to a fifth aspect, in the liquid crystal display device according to the second aspect, at least one of the light source and the three-color separating member or the three-color combining member and the projection lens is provided. By providing the polarization beam splitter, the contrast ratio of the enlarged color image can be further improved.

According to a sixth aspect of the present invention, in the liquid crystal display device according to the second aspect, the three-color separating member is composed of a cross-type plate-shaped filter, and the three-color synthesizing member is a cross-type prism-shaped filter. Since it is composed of, when the illumination light from the light source, which is indefinite polarized light, is separated into three colors,
Even when a low cost type liquid crystal display device that does not require color separation performance is configured by using a cross-type plate-shaped three-color separation member, if a cross-type prism-shaped three-color combination member is used during three-color combination, indefinite polarization Since the S-polarized light or the P-polarized light separated into three different colors are color-synthesized, the three-color separation performance is not affected by the use of the cross-type plate-shaped three-color separation member. A color image can be enlarged and displayed in high quality, and a liquid crystal display device can be provided at low cost.

Further, according to claim 7, in the liquid crystal display device according to claim 1 and claim 2,
Since the phase plate is provided on either the back side or the front side of the transmissive liquid crystal panel, the transmissive liquid crystal panel used is
Depending on whether it is a normally black type TN cell type or a normally white type TN cell type, the image display is set to either normally black or normally white by selectively inserting a phase plate. It becomes possible.

[Brief description of drawings]

FIG. 1 is a perspective view showing a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a partially modified liquid crystal display device according to a first embodiment of the present invention.

FIG. 3 is a perspective view showing a partially modified liquid crystal display device according to a first embodiment of the present invention.

FIG. 4 is a perspective view showing a liquid crystal display device according to a second embodiment of the present invention.

FIG. 5 is a perspective view showing a liquid crystal display device according to a third embodiment of the present invention.

FIG. 6 is a plan view of a liquid crystal display device according to a third embodiment of the present invention, in which (A) shows a lamp light source and a polarization beam splitter on an incident side, and (B) shows an outgoing side. It is a figure showing a polarization beam splitter and a projection lens.

FIG. 7 is a perspective view showing a partially modified liquid crystal display device according to a third embodiment of the present invention.

8 is a perspective view showing the three-color separating member and the three-color combining member shown in FIGS. 5 to 7, (A) showing a cross prism filter, and (B) showing a cross plate. It is a figure showing the filter of.

FIG. 9 is a diagram for explaining an example of a liquid crystal display device in a conventional example.

FIG. 10 is a diagram for explaining a liquid crystal display device of another example in the conventional example.

[Explanation of symbols]

1A ... Liquid crystal display device of the first embodiment, 1B, 1C ... Liquid crystal display device of modification of the first embodiment, 2 ... Transmissive liquid crystal panel, 2a ... Rear surface, 2b ... Front surface, 3, 4 ... Polarizing beam splitter, 5 ... Light source (lamp light source), 6 ... Projection lens,
7 ... Screen, 20 ... Liquid crystal display device of the second embodiment, 2
1 ... Phase plate (λ / 2 plate), 30A ... Liquid crystal display device of third embodiment, 30B ... Liquid crystal display device of modified example of third embodiment, 31 ... Transmissive liquid crystal panel for red light, 32 ... Green Transmissive liquid crystal panel for light, 33 ... Transmissive liquid crystal panel for blue light, 31a to 33a ... Rear surface, 31b to 33b ... Front surface, 34, 35 ... Polarizing beam splitter for red light, 3
6, 37 ... Polarizing beam splitter for green light, 38, 3
9 ... Polarizing beam splitter for blue light, 40 (40A,
Or 40B) ... three color separation member, 41 (41A, or 41)
B) ... 3-color synthesizing member, 42 ... Light source (lamp light source), 43
... Projection lens, 44, 45 ... Polarization beam splitter for improving the contrast ratio.

Claims (7)

[Claims] 1. A liquid crystal display device for illuminating the back surface of one transmissive liquid crystal panel with illumination light from a light source, and enlarging and displaying image data displayed on the front surface of the transmissive liquid crystal panel on a screen by a projection lens. 2. A liquid crystal display device, characterized in that polarizing beam splitters are provided on the back side and the front side of a transmissive liquid crystal panel having no polarizing plate. 2. Illumination light from a light source is converted into R by a three-color separation member.
An image corresponding to each color displayed on the front surface of the transmissive liquid crystal panel of each color is obtained by irradiating the back surface of the transmissive liquid crystal panel corresponding to each color with the separated light of three colors GB. The data is color-synthesized by a 3-color synthesizing member,
In a liquid crystal display device that magnifies and displays one color image data emitted from a color combination member on a screen by a projection lens, a polarization beam splitter is provided on the back side and front side of a transmissive liquid crystal panel of each color without a polarizing plate. A liquid crystal display device characterized by being provided independently for each color. 3. The liquid crystal display device according to claim 2, wherein each optical path length from the light source to the transmissive liquid crystal panel of each color is set to be substantially equal, and from the transmissive liquid crystal panel of each color to the projection lens. The liquid crystal display device is characterized in that the respective optical path lengths are set to be substantially equal to each other. 4. The liquid crystal display device according to claim 2, wherein the polarization beam splitters provided independently for each color are formed with wavelength selectivity corresponding to the transmission type liquid crystal panel of each color. Liquid crystal display device characterized by. 5. The liquid crystal display device according to claim 2, further comprising a polarization beam splitter between at least one of the light source and the three-color separating member or between the three-color combining member and the projection lens. A liquid crystal display device characterized by being provided. 6. The liquid crystal display device according to claim 2, wherein the three-color separating member is a cross-type plate-shaped filter, and the three-color synthesizing member is a cross-type prism-shaped filter. Liquid crystal display device. 7. The liquid crystal display device according to claim 1 or 2, wherein a phase plate is provided on either the back side or the front side of the transmissive liquid crystal panel.