JP3537898B2 - 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 a display device of a liquid crystal light valve type, and more particularly to a display device in which utilization efficiency of light applied to a liquid crystal panel is improved.

[0002]

2. Description of the Related Art Conventionally, liquid crystal projection displays have
Although it is inferior to the CRT system in terms of high image quality, it has attracted attention because it is easy to make the set compact and lightweight and a large screen can be obtained.

FIG. 1 shows a three-panel single-lens type liquid crystal projection display, in which a light from a light source 1 passes through an interference filter 2, and then reflects a B (blue) color light only. Light of a specific color is reflected by a dichroic mirror 4 that reflects only G (green) light and a dichroic mirror 5 that reflects only R (red) light.

[0004] The B (blue) light reflected by the dichroic mirror 3 passes through the liquid crystal light valve 8 for B by the dichroic mirror prism 6 and then reaches the dichroic mirror prism 11 side. The G (green) light reflected by the dichroic mirror 4 passes through the G liquid crystal light valve 9 and reaches the dichroic mirror prism 11 side. The R (red) light reflected by the dichroic mirror 5 passes through the R liquid crystal light valve 10 by the dichroic mirror prism 5 and then reaches the dichroic mirror prism 11 side.

The dichroic mirror prism 11 combines the respective colors of R (red), G (green), and B (blue) and projects them on a screen 13 by a projection lens 12.

Here, dichroic mirror prism 1
In FIG. 1, R (red) and B (blue) light are guided to the projection lens 12 by one reflection and G (green) light is transmitted by transmission, so that the R and B liquid crystal light valves 8 and 10 The liquid crystal alignment distribution with the G liquid crystal light valve 9 is set to be plane symmetric with each other.

Here, the R and G components have an 80 degree clockwise twist structure, and the G components have an 80 degree counterclockwise twist structure. The scanning direction of the X-line shift registers of the liquid crystal light valves 6 and 10 for R and B and the scanning direction of the X-line shift register of the liquid crystal light valve 9 for G are opposite to each other. Thus, the R, B light image and the G light image are formed symmetrically with respect to the vertical axis (mirror inversion axis).

[0008]

By the way, in the above-mentioned conventional liquid crystal projection type display, the light from the light source 1 includes a P-polarized component (light in the in-plane vibration direction) and an S-polarized component (light in the in-plane vibration direction). And light in the vertical direction).
When this light passes through the R liquid crystal light valve 10, the G liquid crystal light valve 9, and the B liquid crystal light valve 8, only one of the P-polarized light and the S-polarized light is transmitted. That is, on both sides of each of the liquid crystal panel surfaces of the R liquid crystal light valve 10, the G liquid crystal light valve 9, and the B liquid crystal light valve 8, polarizing plates whose polarizing surfaces are twisted by 90 degrees are disposed. Since the light from the light source 1 is polarized into linearly polarized light by the polarizing plate, only one of the P-polarized light and the S-polarized light is used, and the utilization rate of the light from the light source 1 is maximized. However, since it is set to 50%, there is a problem that the light use efficiency is poor.

As shown in FIG. 2, the shape of light from the light source 1 is generally circular, and the panel 15
Has a rectangular shape, so that there is a region that extends off the panel 15 as shown by oblique lines, and there is a problem that the area utilization efficiency of light is deteriorated.
Such deterioration of the light area utilization efficiency becomes more remarkable as the aspect ratio of the panel 15 increases.

[0010] The present invention has been made in view of such circumstances, and has as its object to provide a display device capable of improving light use efficiency.

[0011]

According to the first aspect of the present invention,
A light source and a P-wave or an S-wave of light emitted from the light source
While with passing of, P-wave or a prism array for reflecting the other S-wave, said other of said P-wave or S-wave reflected by the prism array P-wave or S
Is converted into one of the waves and a converting means to be incident on the prism array, wherein the P-wave or S other of the P-wave or S-wave reflected by the prism array passes through the prism array by said converting means By being converted into one of the waves, a circular spot emitted from the light source is obtained.
Especially double-wave of Tsu bets light passes through the prism array
Thus, it becomes an elliptical spot light .

According to a second aspect of the present invention, the conversion means includes:
The S wave or P reflected by the prism array
A λ / 4 wavelength plate that polarizes either component of the wave to a １ ／ wavelength, and reflects the passing light polarized to a 波長 wavelength by the λ / 4 wavelength plate. And a reflecting mirror for re-entering the light. The reflected light reflected by the reflecting mirror is converted into the P wave or the S wave when passing through the λ / 4 wavelength plate, and then passes through the prism array. Features.

[0013]

In the display device according to the present invention, the S wave or the P wave reflected by the prism array is converted into the P wave or the S wave passing through the prism array by the conversion means.

When converting the S-wave or P-wave reflected by the prism array into a P-wave or an S-wave, λ / 4
The S-wave or P-wave can be polarized to P-wave or S-wave by the wave plate.

Furthermore, when both waves of light emitted from the light source pass through the prism array, they are formed into an elliptical shape by refraction, so that the spot light from the light source protrudes from the rectangular panel as in the related art. Area is reduced as much as possible, and the area utilization efficiency of light increases. That is, the elliptical spot light after passing through the prism array is
By appropriately setting the refractive index of the prism array, the prism apex angle, and the incident angle of light from the light source to the prism array, the elliptical shape of the spot light can be controlled, and the spot light can be applied to the panel. This is because the area utilization efficiency of light is increased by controlling so that the protruding area is reduced.

Therefore, both waves of the light emitted from the light source can pass through the prism array, and the area of the spot light from the light source that protrudes from the rectangular panel can be reduced as much as possible. Use efficiency is improved.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 3 shows an embodiment of the display device of the present invention. As shown in FIG. 1, a light source 22 having a lamp 21 disposed at a focal position of a concave mirror 20 is provided. The light from the lamp 21 is reflected by the concave mirror 20 to become circular parallel light including P-polarized light (light in the in-plane vibration direction) and S-polarized light (light in a direction perpendicular to the in-plane vibration direction). You.

The parallel light from the light source 22 is
As shown in FIG. 4, P-polarized light is transmitted through the prism array 30 and emitted as shown in FIG. 4.

On the other hand, the remaining S-polarized light is
After being reflected by the S-polarized selective reflection surfaces 30a and 30b of 0,
The light passes through a λ / 4 wavelength plate 31 as a converting light means, and is further turned back by a reflecting mirror 32 as a converting light means. That is, when the S-polarized light reciprocates through the λ / 4 wavelength plate 31, a λ / 2 phase is generated, and the S-polarized light is turned into the P-polarized light and turned back to the prism array 30 side.
As shown in (2), the light is transmitted through the prism array 30 and emitted, and is combined with the P-polarized light.

Here, as shown in FIG.
When the refracted light 41 and the inclined surface 42 of the prism 40 are parallel to each other, the prismatic prism 40 increases the light use efficiency of the light from the light source 22. , Not only is precision required in molding, but birefringence occurs inside,
A prism array 30 having a plurality of prisms 40 is used.

Incidentally, the lamp incident angle a in the figure is 41.9618 degrees, and the prism apex angle b is 26.60.
56 degrees, and the refractive index Nd is 1.493 (PMMA) 1
It is. Thus, the light source 22 that has passed through the prism 40
Spot light from Because is an elliptical shape by refraction of the prism 40, a rectangular panel 15 shown in FIG. 2
If a is inscribed in elliptical light spot, compared to the case where the panel 15 is inscribed in a circular shape of the spot light, since the region will protrude from the panel 15 is small, the area utilization efficiency of light is enhanced. Such improvement in the light area utilization efficiency becomes more remarkable as the aspect ratio of the panel 15 increases.

Next, the operation of the display device having such a configuration will be described. When the P-polarized light and the S-polarized light included in the parallel light from the light source 22 reach the prism array 30, only the P-polarized light passes through the prism array 30. The remaining S polarized light is the S polarized light selective reflection surface 30 of the prism array 30.
After being reflected by a and 30b, the light passes through the λ / 4 wavelength plate 31 and is returned to the prism array 30 side by the reflecting mirror 32. At this time, the S-polarized light that has passed through the λ / 4 wavelength plate 31 is converted into P-polarized light by the action of the λ / 4 wavelength plate 31, transmitted through the prism array 30, and combined with the previous P-polarized light. Although the utilization efficiency of light is 50% at maximum in theory, substantially all of the light from the light source 22 can be utilized, and the utilization efficiency is 100% at maximum in theory.

Thus, since both P-polarized light and S-polarized light are used, the light use efficiency is improved. At this time, as described in FIG. 6, the spot light passing through the prism array 30, since it is an elliptical shape by refraction of the prism array 30, as described above, rectangular panel 1
If 5 is inscribed in elliptical light spot, compared to the case where the panel 15 is inscribed in a circular shape of the spot light, the panel 15
Since the area that protrudes from the area is reduced, the area utilization efficiency of light is improved.

As described above, in this embodiment, the light from the lamp 21 of the light source 22 is reflected by the concave mirror 20, and the P-polarized light is transmitted through the prism array 30 and emitted, and the S-polarized light of the prism array 30 is emitted. After the S-polarized light reflected by the selective reflection surfaces 30a and 30b is polarized to １ ／ wavelength by the λ / 4 wavelength plate 31 to become P-polarized light, and then turned back to the prism array 30 side by the reflecting mirror 32,
Since the prism array 30 so as to transmit to exit, it is possible to utilize both the P polarized light and S-polarized light, the light use efficiency is enhanced.

Further, the P-polarized light of the light emitted from the light source 22 and the polarized light of the λ / 4 wavelength plate 31 are
When it passed through the, because it is an elliptical shape by the refractive index of the prism array 30, if the rectangular panel 15 is inscribed in elliptical light spot, the inner is panel 15 in conventional circular spot light Since the area that protrudes from the panel 15 is made smaller than in the case where it is in contact, the area utilization efficiency of light is increased.

In this embodiment, the prism array 30
Has been described as a case where the component of light passing through is P-polarized light, but may be S-polarized light instead of P-polarized light.

[0027]

As described above, according to the display device of the present invention, the S or P wave reflected by the prism array is converted into the P or S wave passing through the prism array by the conversion means. did. When converting the S wave or the P wave reflected by the prism array into the P wave or the S wave, the S wave or the P wave is converted into the P wave or the P wave by the λ / 4 wavelength plate.
It can be polarized into waves or S-waves.

Further, when both waves of the circular spot light emitted from the light source pass through the prism array, they are formed into an elliptical shape by refraction, so that the light from the light source that protrudes from the rectangular panel as in the related art. Since the area of the spot light is reduced as much as possible, the area utilization efficiency of the light is improved.
That is, the spot light having an elliptical shape after passing through the prism array can be adjusted by appropriately setting the refractive index of the prism array, the prism apex angle, and the incident angle of light from the light source to the prism array. This is because the shape can be controlled, and the area utilization efficiency of light is increased by controlling the area where the spotlight protrudes from the panel so as to reduce the area.

Accordingly, both waves of the light emitted from the light source can be passed through the prism array, and the area of the spot light from the light source which protrudes from the rectangular panel can be reduced as much as possible. Use efficiency is improved.

[Brief description of the drawings]

FIG. 1 is a view showing a conventional three-panel single lens type liquid crystal projection display.

FIG. 2 is a diagram showing a state in which a rectangular panel is inscribed in a circular spot light from a conventional light source.

FIG. 3 is a diagram showing one embodiment of a display device of the present invention.

FIG. 4 is a diagram showing a state in which only P-polarized light has transmitted through a prism array in the display device of FIG. 3;

FIG. 5 is a diagram showing a state in which S-polarized light reflected by a prism array in the three display devices in FIG. 3 is converted into P-polarized light and then transmitted through the prism array again.

FIG. 6 is a diagram illustrating the operation of the prism array of FIG. 3;

[Explanation of symbols]

20 concave mirror 21 lamp 22 light source 30 Prism array 30a, 30b S-polarized selective reflection surface 31 λ / 4 wavelength plate 32 Reflector

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02B 5/04 G02F 1/13357

Claims (2)

(57) [Claims] And 1. A light source, with passing one of the P wave or S wave of the light emitted from the light source, P-wave or
A prism array that reflects the other of the S waves, and the other of the P wave or the S wave reflected by the prism array.
Conversion means for converting the P-wave or S-wave into one of the P-waves and making the P-wave or S-wave incident on the prism array, wherein the other of the P-wave or S-wave reflected by the prism array passes through the prism array by the conversion means The P-wave or
The display device, wherein both waves of the circular spot light emitted from the light source are converted into one of the S waves to become elliptical spot lights by passing through the prism array. 2. The λ / 4 wavelength plate, comprising: a λ / 4 wavelength plate for polarizing either one of the S wave and the P wave reflected by the prism array to １ ／ wavelength; Reflects the transmitted light polarized to １ ／ wavelength,
And a reflecting mirror for re-entering the λ / 4 wavelength plate, wherein the reflected light reflected by the reflecting mirror is converted into the P wave or S wave when passing through the λ / 4 wavelength plate, The display device according to claim 1, wherein the display device passes through a prism array.