JP2605946Y2 - LCD projector - Google Patents

Description

[Detailed description of the invention]

[0001]

The present invention relates to a liquid crystal display (hereinafter referred to as LC).
D) is intended to realize a high-brightness projection display.

[0002]

2. Description of the Related Art FIG. 4 is a perspective view of a conventional LCD projector using a laser. In FIG. 1, a coherent laser beam from a laser 1 is projected on a screen 3 by a polygon mirror 2 and converted into a linear image.

Further, after incoherent light from a light source (not shown) passes through one LCD panel 4, it is converted into a planar image, and is enlarged and projected from the projection lens 5 onto the screen 3 (see FIG. 62). -27340).

[0004]

[Problem to be Solved by the Invention] Such a single LC
In a color LCD projector using D, the most problematic problem is that the brightness of an image projected on a screen is low. This is because the aperture ratio is 40%
, The transmittance of the color filter is as low as 30%, the polarizing plate uses only 50% of light in principle, and an incoherent high-luminance light source cannot be obtained.

In a display device that scans a semiconductor laser, when continuous light emission is required as in an image, the brightness of the semiconductor laser gradually decreases when the threshold voltage of the semiconductor laser is gradually increased and driving is performed at a voltage in a certain range. There is also a drawback that only linear images can be obtained. The present invention has been made in view of the above-described problems, and has as its object to obtain high and stable luminance in an LCD projector using a semiconductor laser.

[0006]

According to a first aspect of the present invention, there is provided an LCD projector comprising three types of independent laser light sources of R, G, and B, an optical scanner, an LCD panel, and a projection lens. , G, and B light on the same optical axis. The LCD projector according to claim 2, wherein three types of independently driven lasers of R, G, and B, an optical scanner that scans laser light from the laser, an LCD panel that receives the scanned laser light, And a projection lens for projecting a laser beam from the LCD panel onto a screen.
In the CD projector, the length parallel to the scanning direction of the R, G, and B laser beams selected and scanned on the same optical axis in a specific arrangement is set to be shorter than the width of the light shielding film in the LCD panel. This is the gist.

According to a third aspect of the invention, there is provided an LCD projector comprising:
G, B three types of independent laser light source, optical scanner,
In the LCD projector including the LCD panel and the projection lens, the gist of the present invention is to emit laser beams of respective colors only at pixel positions corresponding to RGB colors. The LCD projector according to claim 4, wherein three types of independently driven lasers of R, G, and B, an optical scanner that scans laser light from the laser, an LCD panel that receives the scanned laser light, In an LCD projector composed of a projection lens for projecting a laser beam from an LCD panel onto a screen, the R, G, and B laser beams selected in a specific arrangement and scanned on the same optical axis are perpendicular to the scanning direction of the laser beam. The gist is that the length is set to be longer than the length perpendicular to the scanning direction of one pixel in the LCD panel.

[0008]

The operation of the present invention is listed below. Since the laser light source has small chromatic aberration, it is easy to narrow the beam to the pixels of the LCD panel. There is no light loss due to the color filter or the dichroic mirror, and the light loss is limited to the polarizing plate alone, so that the brightness on the screen increases.

Since three independently driven R, G, and B lasers having high monochromaticity are used, a projected image that is bright, has high color purity, and is excellent in color reproducibility is obtained. Since the R, G, and B laser beams scanned by the LCD panel emit light alternately and discontinuously, the brightness of the semiconductor laser is less likely to decrease over a long period of use.

Since the light source is a laser light source, the light density is very high, so that a high brightness light source can be easily obtained. With the above-described operation, a single-panel high-brightness LCD projector can be obtained using the a-Si TFT panel.

[0011]

FIG. 1 is a block diagram of an LCD projector according to the present invention. As shown in FIG. 1, an elliptical coherent laser beam from a semiconductor laser 6 has a GaAs semiconductor lens 7 having a low refractive index at the center and a high refractive index at the left and right.
As a result, a laser beam having a vertically long rod shape is formed, and the red, green, and blue laser beams are combined on the same optical axis by the respective semiconductor lenses 7.

A rod-shaped laser beam having high monochromaticity consisting of the three primary colors of R, G, and B is applied to an LCD panel 4 by an optical scanner 8.
Is scanned up, down, left, and right, and is converted into an image having a frequency of about 300 Hz by passing through an LCD panel.

The LCD panel 4 is composed of m rows and n columns of pixels. When the rod-shaped laser light is about one pixel long,
The bar-shaped laser beam is horizontally scanned from the first row, first column to first row n column, and then sequentially scanned from row R2, R3,..., Rm.

Each semiconductor laser has a corresponding R, G, B
Light is emitted only at the pixel position, and the emission time t is represented by t = (pixel size) / {(scan speed) × 3}. When the rod-shaped laser light has a length approximately equal to the vertical length of m pixels, the rod-shaped laser light only needs to be scanned once horizontally and the structure of the optical scanner is simplified.

In either case, the LCD panel is driven in a dot-sequential manner in synchronization with the laser light, and the position of the opening for the laser light moves.

Here, a-SiT is used as the LCD panel.
When an FT panel is used, the major axis of the laser beam diameter is longer than the vertical direction of the pixel electrode, and the minor axis is shorter than the drain bus line. The laser beam from the LCD panel is projected onto the projection lens 5
Is projected on the screen 3 via the screen and recognized as an image.

FIG. 2 is a plan view showing the LCD panel and the position of a laser beam that scans the LCD panel. In FIG. 2, the rod-shaped laser light 9 alternately scans horizontally between a light-shielding film 10 that does not transmit light and an opening 11 that transmits light on the LCD panel. In the column labeled R, only the red (R) semiconductor laser is driven, in the column labeled G, only the green (G) semiconductor laser is driven, and in the column labeled B, Only the blue (B) semiconductor laser is driven.

The width w of the laser light 9 is smaller than the width W of the light-shielding film 10 between the two openings 11 serving as pixels of the LCD panel. Similarly, the height h of the laser beam 9 is larger than the height H of the opening 11. When the shape of the rod-shaped laser light 9 is set to w <W, the laser light scanned does not mix different colors between adjacent openings, and has high color purity.
A CD projector becomes possible.

Further, the shape of the rod-shaped laser light 9 is defined as h> H
By doing so, it is possible to tolerate a certain amount of vertical fluctuation of the scanned laser light caused by the optical scanner. Subsequently, the driving timings of the three types of semiconductor lasers used in the present invention will be described.

FIG. 3 is a diagram showing driving timings of three types of semiconductor lasers of R, G and B which are alternately driven on the LCD panel. One line of the LCD panel is C1, C2,..., C7
The openings 11 through which the R, G,..., R laser beams pass are selected by the LCD panel in a dot-sequential manner (FIG. 3A).

The pixel selected by the optical scanner is LC
In the case of the R opening of the D panel, only the R laser is driven (FIG. 3b). Similarly, when the pixel selected by the optical scanner is the G aperture of the LCD panel, only the G laser is emitted (FIG. 3c). When the pixel selected by the optical scanner is the B aperture of the LCD panel, only the B laser is emitted. The laser is driven (FIG. 3d).

As is apparent from the figure, the emission interval of the laser light of each color is three times longer than that of a single light source, so that the laser current does not decrease even after long use. When the semiconductor laser is driven as shown in FIG. 3, the brightness of the projected image on the screen does not decrease even when the LCD projector is continuously used for several tens of hours. As described above, when a vertically long laser beam is used for an a-Si TFT LCD, the beam shape can be adjusted to the shape of the pixel electrode, and light loss becomes small. Become irrelevant.

In addition, a single plate type or a color filter may not be used, and if a polarizing laser is used, only one polarizing plate may be used, so that the light utilization factor is remarkably improved to about 80%. . Note that the lateral width of the opening of the LCD panel only needs to be equal to or greater than the width W of the light-shielding film.

Further, it is desirable to use a polymer dispersion type panel without a polarizing plate as the LCD panel, as compared with a TN type panel using a polarizing plate having a relatively high transmittance. Further, the lens is not limited to a semiconductor lens, and may be a cylindrical lens using optical glass. Alternatively, the driving method of the LCD panel may be line-sequential driving when the width of the laser beam can scan all the rows simultaneously.

[0025]

According to the present invention, high and stable luminance can be obtained in an LCD projector using a semiconductor laser.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an LCD projector of the present invention.

FIG. 2 is a plan view of the LCD panel of the present invention and a laser beam.

FIG. 3 is a driving timing diagram of the semiconductor laser of the present invention.

FIG. 4 is a configuration diagram of an LCD projector.

[Explanation of symbols]

 Reference Signs List 1 laser 2 polygon mirror 3 screen 4 LCD panel 5 projection lens 6 semiconductor laser 7 semiconductor lens 8 optical scanner 9 laser beam 10 light shielding film 11 opening

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02F 1/13 505 G02F 1/1335 G09F 9/30

Claims (4)

(57) [Scope of request for utility model registration] 1. An LCD projector comprising three types of independent laser light sources of R, G, and B, an optical scanner, an LCD panel, and a projection lens, scans R, G, and B lights on the same optical axis. LCD projector characterized by making it. 2. An independently driven laser of three types of R, G and B, an optical scanner for scanning a laser beam from the laser, and an LCD for entering the scanned laser beam.
In an LCD projector composed of a panel and a projection lens for projecting a laser beam from an LCD panel onto a screen, a scanning direction of R, G, and B laser beams selected and scanned in a specific arrangement on the same optical axis. An LCD projector characterized in that the length parallel to the width is set shorter than the width of the light shielding film in the LCD panel. 3. An LCD projector comprising three types of independent laser light sources of R, G, and B, an optical scanner, an LCD panel, and a projection lens, wherein only pixel positions corresponding to each of RGB colors are provided . An LCD projector that emits a laser of each color . 4. R, G, and B independently driven lasers, an optical scanner for scanning laser light from the laser, and an LCD for entering the scanned laser light.
In an LCD projector composed of a panel and a projection lens for projecting a laser beam from an LCD panel onto a screen, a scanning direction of R, G, B laser beams selected and scanned in a specific arrangement on the same optical axis. A length perpendicular to the LCD panel is set longer than a length perpendicular to a scanning direction of one pixel in the LCD panel.