JP2612361B2 - LCD projector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a liquid crystal projector.

[Technique of the invention]

The liquid crystal projector uses a transmission type liquid crystal display panel to display an image, and enlarges and projects a display image of the liquid crystal display panel on a screen surface by a projection lens. The liquid crystal projector has the following configuration. I have.

That is, FIG. 11 shows a conventional liquid crystal projector, in which 1 is a transmissive dot matrix liquid crystal display panel, 2 is a light source unit provided behind the liquid crystal display panel 1, and this light source unit 2 is The liquid crystal display panel 1 is illuminated with illumination light A parallel to the optical axis O, which comprises a light source lamp 3 and a parabolic mirror reflector 4 that reflects light emitted from the light source lamp 3 in a direction parallel to the optical axis O. Configuration. FIG. 11 shows a liquid crystal projector in which the reflector 4 of the light source unit 2 is a parabolic mirror reflector. However, in a liquid crystal projector using a normal elliptical mirror reflector as the reflector, a relay lens is provided in the light source unit. The relay lens corrects the reflected light from the reflector into parallel light using the relay lens and irradiates the liquid crystal display panel. Reference numeral 5 denotes a projection lens provided in front of the liquid crystal display panel 1, and light transmitted through the liquid crystal display panel 1, that is, a display image of the liquid crystal display panel 1 is projected onto a screen S enlarged by the projection lens 5. It is supposed to be. The liquid crystal display panel 1 is of a TN (twisted nematic) type, and the liquid crystal display panel 1 is inclined at a predetermined angle with respect to the optical axis O so that the incidence efficiency of the illumination light A from the back side is the best. It is provided. Reference numeral 7 denotes a frame-shaped light-shielding plate that supports the liquid crystal display panel 1. Among illumination light A from the light source unit 2, light incident on the display unit (display area) 1a of the liquid crystal display panel 1 is a liquid crystal display. Although the light is transmitted through the panel 1, the light emitted to the outside of the display unit 1a is blocked by the liquid crystal display panel and the light shielding plate 7, so that the screen S
On the surface, only the light transmitted through the display section 1a of the liquid crystal display panel 1 is projected.

In other words, this liquid crystal projector uses the liquid crystal display panel 1
According to this liquid crystal projector, there is no need to insert and extract a slide film as in a normal projector using a slide film, and a moving image such as a television image can be obtained. Images can also be projected on the screen surface.

By the way, in the above-mentioned liquid crystal projector, in order to project a complete image on the screen S, it is necessary to make the display unit 1a of the liquid crystal display panel 1 emit the illumination light A over the entire area. Display section 1a
Is generally rectangular, whereas the luminous flux of the illumination light A from the light source unit 2 reflected by the reflector 4 is generally circular, so that if the luminous flux diameter of the illumination light A is small, the liquid crystal display panel 1 The illumination light does not enter the corners of the display unit 1a, and the image of the screen with the corners missing is projected on the screen S surface.

For this reason, in the above-mentioned liquid crystal projector, the diameter of the reflector 4 of the light source unit 2 is adjusted so that the luminous flux diameter of the illumination light A radiated toward the liquid crystal display panel 1 is changed to the rectangular display unit of the liquid crystal panel 1.
The display area 1a of the liquid crystal display panel 1 is illuminated over the entire area by selecting the area to be sufficiently larger than the circumscribed circle of the area 1a. Can be projected onto the screen S.

[Problems to be solved by the invention]

However, in the conventional liquid crystal projector, the illumination light A of a circular luminous flux from the light source unit 2 is directly radiated to the liquid crystal display panel 1.
The amount of unused light (light outside the display unit 1a and the light shielded by the light blocking plate 7) that irradiates parts other than 1a is very large, and therefore, the illumination light A from the light source unit 2 cannot be used efficiently. Had. This is because, as described above, the display unit 1a of the liquid crystal display panel 1 has a rectangular shape, whereas the luminous flux of the illumination light A from the light source unit 2 reflected by the reflector 4 is circular. Liquid crystal display panel 1
If the display unit 1a is installed with the longitudinal direction of the display unit 1a being horizontal as shown in FIG. 12, the amount of unused light that irradiates parts other than the display unit 1a is extremely low above and below the display unit 1a. Therefore, most of the illumination light A from the light source unit 2 is wasted.

The present invention has been made in view of the above circumstances, and has as its object to reduce the amount of unused light that irradiates a portion other than the display unit of the liquid crystal display panel in the illumination light from the light source unit. To make the illumination light from the light source part available to the image efficiently, and to increase the density of light incident on the display part of the liquid crystal display panel to project a bright image with high brightness on the screen surface. It is an object of the present invention to provide a liquid crystal projector capable of performing the following.

[Means for solving the problem]

According to the present invention, a liquid crystal display panel having a rectangular display portion is provided.
In a liquid crystal projector including a light source unit that emits illumination light toward the liquid crystal display panel and a projection lens that enlarges and projects a display image of the liquid crystal display panel on a screen surface, the light source unit has a substantially circular cross section. The liquid crystal display panel generates illumination light, and the liquid crystal display panel is disposed at a predetermined angle with respect to an optical axis of the illumination light from the light source unit in a narrow direction of a display unit of the liquid crystal display panel, and the light source unit and the liquid crystal are arranged. A first optical element for condensing the luminous flux of the illumination light from the light source unit only in the narrow direction of the display unit of the liquid crystal display panel between the display unit and the display panel, and a condensing action of the first optical element And a second optical element for correcting the light beam whose width has been compressed by the above into a parallel light beam.

[Action]

That is, according to the present invention, the luminous flux of the illumination light
According to the invention, the light beam is condensed only in the narrow direction of the display portion of the liquid crystal display panel by the optical element, and this light beam is again converted into a parallel light beam by the second optical element to illuminate the liquid crystal display panel. For example, it is difficult to irradiate both sides in the narrow direction of the display unit by compressing only the light beam width in the narrow direction of the display unit while keeping the light beam width in the longitudinal direction of the display unit of the liquid crystal display panel as the light beam width from the light source unit. Since the amount of light used can be reduced, the amount of unused light that irradiates a portion other than the display unit of the liquid crystal display panel can be reduced, and the illumination light from the light source unit can be efficiently used for projecting an image. Moreover, in the present invention, since the luminous flux of the illuminating light from the light source unit is condensed and radiated to the liquid crystal display panel, of the unused light conventionally irradiating a part other than the display unit, A considerable amount of light can be incident on the display of the liquid crystal display panel to increase the density of light incident on the display,
Therefore, since the illumination luminance of the liquid table display panel can be increased, a bright image with high luminance can be projected on the screen surface.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a transmissive dot matrix liquid crystal display panel in which a display unit 1a has a rectangular shape, and the liquid crystal display panel 1 is arranged such that the longitudinal direction of the display unit 1a extends horizontally as shown in FIG. In the state of being turned, it is supported by a frame-shaped light shielding plate 7 at an angle to the optical axis O. This liquid crystal display panel 1 is a color liquid crystal display panel provided with three primary color filters 8 on its front side (projection lens side). The three primary color filters 8 are formed by alternately arranging three color filters RF, GF, and BF of red (R), green (G), and blue (B) as shown in FIG. The color filter 8 is provided such that each of the stripe filters RF, GF, and BF faces each operation electrode or signal electrode (not shown) of the liquid crystal display panel 1.

Reference numeral 2 denotes a light source unit which is disposed behind the liquid crystal display panel 1 and illuminates the liquid crystal display panel 1 from the back side. The light source unit 2 is, like the conventional liquid crystal projector shown in FIG. Illumination light parallel to the optical axis O toward the liquid crystal display panel 1 comprising a light source lamp 3 such as the above, and a parabolic mirror reflector 4 for reflecting the light emitted from the light source lamp 3 in a direction parallel to the optical axis O. A0 is irradiated. Reference numeral 5 denotes a projection lens provided in front of the liquid crystal display panel 1, and a display image of the liquid amount display panel 1 is enlarged and projected on the screen S by the projection lens.

On the other hand, in FIG. 1, reference numerals 9 and 10 denote first and second linear Fresnel lenses provided between the light source unit 2 and the liquid crystal display panel 1, respectively.
Has a function of a convex lens as shown in FIGS. 3 and 4, and the second linear Fresnel lens 10 has a function of a convex lens as shown in FIGS. 5 and 6. The first and second linear Fresnel lenses 9 and 10 have a large number of narrow band-shaped lens portions 9a, 9a and 9a so as to be symmetrical on one side with lens centers L1 and L2 therebetween.
The first linear Fresnel lens 9 is disposed on the light source unit 2 side with its lens surface facing the light source unit 2, and the second linear Fresnel lens 10 has its lens surface Toward the liquid crystal display panel 1
Located on the side. Note that the distance between the first linear Fresnel lens 9 and the second linear Fresnel lens 10 is the first distance.
It is set sufficiently smaller than the focal length of the linear Fresnel lens 9. These linear Fresnel lenses 9 and 10
The belt-like lens portions 9a, 9a and 10a, 10a are installed with their longitudinal directions horizontal, with their lens centers L1, L2 aligned with the optical axis O of the projector.

The first linear Fresnel lens 9 transmits the light flux of the illumination light A0 parallel to the optical axis O from the light source unit 2 to each of the band-shaped lens units 9a, 9
The light is condensed only in the width direction, that is, in the vertical direction of the band-shaped lens portions 9a, 9a, and the illumination light A0 of the circular luminous flux from the light source portion 2 passes through the first linear Fresnel lens 9 and condenses. 7, only the light beam width in the vertical direction is compressed as shown in FIG. 7, and the light beam width in the horizontal direction is not compressed, and goes straight as shown in FIG. The second linear Fresnel lens 10
Is for correcting a light beam whose width in the vertical direction has been compressed by the first linear Fresnel lens 9 into a parallel light beam parallel to the optical axis O.
The light obliquely entering the linear Fresnel lens 10 is expanded by the light expanding action of the second linear Fresnel lens 10 to become light parallel to the optical axis O as shown in FIG. The light that has traveled straight without being affected by the light travels straight through the second linear Fresnel lens 10 as shown in FIG. Therefore, the illumination light A0 of the circular light beam from the light source unit 2 is parallel light A1 of the elliptical light beam as shown in FIG. 2 which is compressed only in the vertical direction, that is, in the narrow direction of the rectangular display unit 1a of the liquid crystal display panel 1. LCD panel 1
Will be irradiated. The elliptical light A1 is emitted from the light source 2
Since the illumination light A0 of the circular luminous flux from the light source unit 2 is compressed only in the vertical direction, the luminous flux diameter of the illumination light A0 from the light source unit 2 is sufficiently larger than the horizontal width (width in the longitudinal direction) of the display unit 1a of the liquid crystal display panel 1. The display unit 1a can be illuminated as it is over the entire horizontal width as long as it is made large, and the vertical width of the elliptical light beam condensed by the first linear Fresnel lens 9 is equal to the vertical width (narrow) of the display unit 1a. The first linear Fresnel lens 9 and the second linear Fresnel lens 9 are adjusted in accordance with the focal length of the first linear Fresnel lens 9 so that this light beam is corrected into parallel light by the second linear Fresnel lens 10 before the light flux becomes smaller than the width (width in the width direction). If the distance from the linear Fresnel lens 10 is selected, the display section 1a can be illuminated over the entire area in the vertical direction.

Thus, in this liquid crystal projector, the light source unit 2 is disposed between the light source unit 2 and the liquid table display panel 1 as described above.
A first linear Fresnel lens 9 for condensing the luminous flux of the illumination light A0 from the liquid crystal display panel 1 only in the narrow width direction of the rectangular display portion 1a, and compressing the width by the condensing action of the first linear Fresnel lens 9 Since the second linear Fresnel lens 10 that corrects the obtained light beam into a parallel light beam parallel to the optical axis O is provided, the illumination light A0 from the light source unit 2 is transmitted in the longitudinal direction of the display unit 1a of the liquid crystal display panel 1. The luminous flux width is a range in which only the luminous flux in the narrow direction of the display unit 1a is not smaller than the width of the display unit 1a in the narrow direction while keeping the luminous flux from the light source unit 2 (a width capable of sufficiently illuminating the entire display unit 1a). The liquid crystal display panel 1 can be compressed and irradiated to the liquid crystal display panel 1. Therefore, according to this liquid crystal projector, compared to the conventional liquid crystal projector that irradiates the illumination light from the light source unit 2 to the liquid crystal display panel 1 as it is, the unused light amount that irradiates both sides in the narrow direction of the display unit 1a. Can be reduced, the amount of unused light irradiating a portion other than the display unit 1a of the liquid crystal display panel 1 can be reduced, and the illumination light from the light source unit 2 can be efficiently used for projecting an image. . Moreover, in the above-mentioned liquid crystal projector, since the light flux of the illumination A0 from the light source unit 2 is condensed and radiated to the liquid crystal display panel 1, the unused light conventionally irradiating parts other than the display unit is used. Can be made to enter the display unit 1a of the liquid crystal display panel 1 to increase the density of light incident on the display unit 1a, and therefore, the illumination brightness of the liquid crystal display panel 1 can be increased. Accordingly, a bright image with high luminance can be projected on the screen S.

In this liquid crystal projector, the light whose light flux width is compressed by the first linear Fresnel lens 9 is converted into parallel light parallel to the optical axis O by the second linear Fresnel lens 10 and then incident on the liquid crystal display panel 1. Therefore, when the light transmitted through the display unit 1a of the liquid crystal display panel 1 is colored through the color filter 8 on the front surface thereof, color mixing does not occur. That is, if the light whose luminous flux width is compressed by the first linear Fresnel lens 9 is directly incident on the liquid crystal display panel 1, the light enters the display portion 1a in the vertical direction of the liquid crystal display panel 1 from an oblique direction. Since the light transmitted through the display unit 1a passes obliquely through the color filter 8 as shown by a broken line in FIG. 9, light passing near the boundary between the stripe filters RF, GF, and BF of the color filter 8 is adjacent. Therefore, the color of the light becomes turbid, but the light beam width is compressed by the first linear Fresnel lens 9 as described above. If the light is converted into parallel light parallel to the optical axis O by the second linear Fresnel lens 10 and then incident on the liquid crystal display panel 1, the liquid crystal display panel 1
9 passes through the color filter 8 as shown by the solid line in FIG. 9, so that double coloring of light is prevented, and a clear color image without color shift and color unevenness is formed on the screen S. Can be projected.

9 and 10 show another embodiment of the present invention. In this embodiment, a first linear Fresnel lens having a convex lens function is used as a second linear Fresnel lens for correcting a light beam whose width in the vertical direction is compressed by the first linear Fresnel lens 9 into a parallel light beam parallel to the optical axis O. A linear Fresnel lens 11 similar to the lens 9 is used. With the second linear Fresnel lens 11 facing the first linear Fresnel lens 9 on its lens surface, the focal length from the first linear Fresnel lens 9 is larger than that of the first linear Fresnel lens 9. Since they are arranged far apart from each other, the same effect as described above can be obtained by this embodiment.

In the above embodiment, the liquid crystal display panel 1 is provided so that the longitudinal direction of the display section 1a is oriented horizontally, but the liquid crystal display panel 1 is oriented with the longitudinal direction of the front section 1a oriented vertically. In this case, a vertically long rectangular screen image may be projected on the screen surface. In such a case, the first linear Fresnel lens 9 and the second linear Fresnel lens 10 or 11 are provided in the vertical direction, and the light source unit is provided. The luminous flux of the illumination light from 2 may be condensed only in the narrow direction of the display section 1a of the liquid crystal display panel 1. In the above embodiment, the color liquid crystal projector that projects a color image on a screen surface using a color liquid crystal display panel has been described.However, the present invention provides a liquid crystal display panel that displays a black and white image to display a black and white image on a screen surface. Of course, the present invention can be applied to a liquid crystal projector for projection.

〔The invention's effect〕

According to the present invention, the light source unit generates illumination light having a substantially circular cross section, and the liquid crystal display panel is disposed at a predetermined angle with respect to the optical axis of the illumination light from the light source unit. A first optical element for condensing the light flux of the illumination light from the light source unit only in a narrow direction of the display unit of the liquid crystal display panel between the panel and the panel; and a light condensing action of the first optical element. The second for correcting the light beam whose width has been compressed into a parallel light beam
The optical element is provided so that light enters the liquid crystal display panel from an optimal direction, and the luminous flux of the illuminating light from the light source section is compressed, its width is further corrected to a parallel luminous flux, and the luminous flux enters the liquid crystal display panel. According to the present invention,
The angle of incidence of light on the liquid table display panel can be kept optimal, and
The light of the light source can be used effectively.

[Brief description of the drawings]

1 to 9 show one embodiment of the present invention.
FIG. 1 is a longitudinal side view of a liquid crystal projector, and FIG.
FIGS. 3 and 4 are sectional views taken along the line II-II of FIG.
FIGS. 5 and 6 are front and side views of the second linear Fresnel lens, and FIGS. 7 and 8 are lateral views showing directions of light transmitted through the linear Fresnel lens. FIG. 9 is an explanatory diagram viewed from the side and above, and FIG. 9 is an explanatory diagram showing the direction of light passing through the color filter on the front surface of the liquid crystal display panel as viewed from the lateral direction. Tenth
The figure is a longitudinal sectional side view of a liquid crystal projector showing another embodiment of the present invention. FIG. 11 is a longitudinal sectional side view of a conventional liquid crystal projector, and FIG. 12 is a sectional view taken along line XII-XII of FIG. 1 ... liquid crystal display panel, 1a ... display unit, 2 ... light source unit,
3 ... light source lamp, 4 ... reflector, 6 ... projection lens, 8 ... color filter, 9 ... first linear Fresnel lens, 10,11 ... second linear Fresnel lens, S ...
screen.

Claims (1)

(57) [Claims] 1. A liquid crystal display panel having a rectangular display section.
In a liquid crystal projector including a light source unit that emits illumination light toward the liquid crystal display panel and a projection lens that enlarges and projects a display image of the liquid crystal display panel on a screen surface, the light source unit has a substantially circular cross section. It generates illumination light, and arranges the liquid crystal display panel at a predetermined angle with respect to an optical axis of the illumination light from the light source unit in a narrow direction of a display unit of the liquid crystal display panel, and the light source unit and the liquid crystal. A first optical element for condensing the luminous flux of the illumination light from the light source unit only in the narrow direction of the display unit of the liquid crystal display panel between the display unit and the display panel, and a condensing action of the first optical element And a second optical element that corrects the light beam whose width has been compressed by the light beam into a parallel light beam.