JPH0723329U - LCD projector - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to improve the low brightness of the screen, which is peculiar to an LCD projector using a dichroic mirror or a color filter, and suppress a decrease in brightness due to continuous oscillation of a semiconductor laser. A length parallel to a scanning direction of R, G, and B laser beams which are pulse-driven alternately on the same optical axis and horizontally scanned is shorter than a width of a light shielding film in the LCD panel,
LC in which the length of laser light perpendicular to the scan direction is longer than the length of one pixel in the LCD panel perpendicular to the scan direction
D projector.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an LCD projector using a liquid crystal display device (hereinafter referred to as LCD), and is particularly intended to realize projection display with high brightness.

[0002]

[Prior art]

 The conventional single-panel LCD projector using a-SiTFT has a problem that the light utilization rate is about 3% of the light source and the brightness is extremely low.

This is due to the low aperture ratio of about 40% of the a-Si TFT panel, the low transmittance of about 30% of the color filter used for color display, and the maximum of one polarizing plate. It is necessary to use two polarizing plates with a transmittance of 50%, which is actually lower than that of 40%, and it is difficult to obtain a long-life, high-brightness light source.

At present, a method is proposed in which three a-SiTFT panels are used instead of a single plate type to improve the actual aperture ratio, or a poly-SiTFT panel is used instead of the a-SiTFT panel to increase the aperture ratio. Has been done.

However, an LCD projector using three a-Si TFT panels is large in size due to the spectrum and requires a large number of optical parts, resulting in a high price. On the other hand, an LCD projector using a poly-Si TFT panel is expensive. Had the disadvantage of raising the panel itself.

Thus, there has been a demand for an LCD projector that does not depend on the aperture ratio and does not use a color filter.

FIG. 4 shows a perspective view of a conventional LCD projector using a laser.

In FIG. 4, the coherent laser light from the laser 1 is projected onto the screen 3 by the polygon mirror 2 and converted into a linear image.

Further, incoherent light from a light source (not shown) passes through one LCD panel 4, is converted into a planar image, and is enlarged and projected on the screen 3 from the projection lens 5 (actual opening 62). No. 27340).

In such a color LCD projector using a single LCD, the biggest problem is that the brightness of the image projected on the screen is low.

This is because the aperture ratio is as low as 40%, the transmittance of the color filter is as low as 30%, the polarizing plate basically uses only 50% of light, and the incoherent high There are some cases where a bright light source cannot be obtained.

On the other hand, in a display device that scans a semiconductor laser, when continuous light emission is required like an image, the threshold value of the semiconductor laser is gradually increased and the luminance is gradually reduced when driven with a voltage within a certain range, or in principle. However, there is a drawback that only linear images can be obtained.

[0013]

[Problems to be solved by the device]

 An object of the present invention is to obtain a planar image in an LCD projector using a semiconductor laser by improving the low brightness peculiar to the LCD and the fluctuation of the brightness of the light source due to the continuous oscillation of the semiconductor laser.

[0014]

[Means for Solving the Problems]

 The present invention comprises three types of independently driven lasers R, G and B, an optical scanner for scanning laser light from the laser, an LCD panel for injecting the scanned laser light, and an LCD panel. In the LCD projector consisting of a projection lens for projecting the laser light of the above, on the screen, the length of the R, G, B laser light selected and scanned in the same optical axis in parallel with the scan direction. Is shorter than the width of the light shielding film in the LCD panel, and the length perpendicular to the scan direction of the laser light is longer than the length perpendicular to the scanning direction of one pixel in the LCD panel.

[0015]

[Action]

 Since the laser light source has small chromatic aberration, it is easy to focus the beam according to the pixel 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, so that the brightness on the screen is increased.

Since three types of independently driven R, G, and B lasers having high monochromaticity are used, a bright projected image with high color purity and excellent color reproducibility is obtained.

Since the R, G, and B laser beams scanned by the LCD panel alternately and discontinuously emit, the brightness of the semiconductor laser is less likely to decrease even after long-term use.

Since it is a laser light source, the light density is very high, so that a high-brightness light source can be easily obtained.

By the above-mentioned operation, a single-panel high-brightness LCD projector can be obtained by using the a-Si TFT panel.

[0021]

【Example】

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

As shown in FIG. 1, the elliptical coherent laser light from the semiconductor laser 6 has a bar shape that is vertically long due to the GaAs semiconductor lens 7 having a low refractive index in the central portion and a high refractive index on the left and right. Laser light.

The red, green, and blue laser lights are combined on the same optical axis by the semiconductor lens.

A highly monochromatic rod-shaped laser beam composed of the three primary colors of R, G, and B is scanned by the optical scanner 8 vertically and horizontally on the LCD panel 4.

The combined light is scanned by an optical scanner and passes through an LCD panel to be converted into an image having a frequency of about 300 Hz.

When the LCD panel 4 is composed of pixels in m rows and n columns and the rod-shaped laser light has a length of about one pixel in the vertical direction, the rod-shaped laser light horizontally extends from the first row to the first column. After scanning to the nth column, R2, R3, ..., Rm are sequentially scanned for each row.

Each semiconductor laser emits light only at the corresponding R, G, B pixel positions, and the emission time t 1 is represented by t = (pixel size) / {(scan speed) × 3}.

Similarly, when the rod-shaped laser light has a vertical length of about m pixels, the rod-shaped laser light scans the horizontal plane only once, which simplifies the structure of the optical scanner.

In either case, the LCD panel is dot-sequentially driven in synchronization with the laser light, and the position of the opening moves with respect to the laser light.

When an a-Si TFT panel is used as the LCD panel, 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.

Laser light from the LCD panel is projected on the screen 3 through the projection lens 5 and is recognized as an image.

Next, the positional relationship on the plane between the rod-shaped laser light used in the present invention and the LCD panel will be shown.

FIG. 2 is a plan view showing the LCD panel and the position of the laser beam scanning the LCD panel.

In FIG. 2, the rod-shaped laser beam 9 alternately scans horizontally between the light-shielding film 10 that does not transmit light and the 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 the column labeled B is written. Only the blue (B) semiconductor laser is driven in the row.

The lateral width w of the laser light 9 is narrower than the width of the light shielding film 10 between the two openings 11 which are pixels of the LCD panel.

Similarly, the height h of the laser beam 9 is larger than the height H of the opening 11.

By setting the shape of the rod-shaped laser light 9 to be w <W, the laser light to be scanned does not mix different colors between adjacent openings, and an LCD projector with high color purity is possible.

Further, by setting the shape of the rod-shaped laser light 9 to be h> H, it becomes possible to allow some blurring of the scanned laser light up and down due to the optical scanner.

Next, drive timings of the three types of semiconductor lasers used in the present invention will be described.

FIG. 3 is a diagram showing drive timings of three types of semiconductor lasers of R, G, and B which are alternately driven on the LCD panel.

A row of the LCD panel is made up of C1, C2, ..., C7, and openings 11 for passing the R, G, ..., R laser beams are selected by the LCD panel in a dot-sequential manner. (Fig. 3a).

When the pixel selected by the optical scanner is the R aperture of the LCD panel, the R only laser is driven (FIG. 3b).

Similarly, if the pixel selected by the optical scanner is the G aperture of the LCD panel, and only the G laser is selected (FIG. 3c), the pixel selected by the optical scanner is the B aperture of the LCD panel. , B only lasers are 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-term 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 if the LCD projector is continuously used for several tens of hours.

As described above, when the vertically long laser beam is used for the a-SiTFT LCD, the beam shape can be matched with the pixel electrode shape, and the light loss becomes small. Therefore, the aperture ratio of the low panel is small on the screen. Irrelevant to the high brightness of.

Further, the single plate type does not need to use a color filter, and if a polarizing laser is used, only one polarizing plate is required, so that the light utilization rate is significantly improved to about 80%. .

The horizontal width of the opening of the LCD panel may be equal to or larger than the width W of the light shielding film, and when the width is the same, the laser is not burdened most.

Further, as the LCD panel, it is desirable to use a polymer dispersion type panel having no polarizing plate, as compared with a TN type panel using a polarizing plate having a relatively high transmittance.

Further, the lens is not limited to the semiconductor lens, and may be a cylindrical lens using optical glass.

Alternatively, the LCD panel driving method may be line-sequential driving when the laser light has a width capable of simultaneously scanning all rows.

[0053]

[Effect of device]

 According to the present invention, it is possible to realize an LCD projector which is composed of coherent light on a screen and which can be used for a long time and has a large number of bright display colors.

[Brief description of drawings]

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

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

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

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

[Explanation of symbols]

 1 Laser 2 Polygon Mirror 3 Screen 4 LCD Panel 5 Projection Lens 6 Semiconductor Laser 7 Semiconductor Lens 8 Optical Scanner 9 Laser Light 10 Light-shielding Film 11 Opening

Claims (4)

[Scope of utility model registration request] 1. An LCD projector comprising three independent laser light sources of R, G and B, an optical scanner, an LCD panel and a projection lens, and scans R, G and B lights on the same optical axis. An LCD projector which is characterized by 2. An LCD projector comprising an R, G, and B independent laser light source, an optical scanner, an LCD panel, and a projection lens, wherein the major axis of the laser beam is longer than the vertical dimension of the pixel. An LCD projector having a rod-like shape whose shorter diameter is shorter than the drain bus line. 3. An LCD projector comprising three types of independent R, G, and B laser light sources, an optical scanner, an LCD panel, and a projection lens, wherein a laser is emitted only at corresponding pixel positions. LCD projector. 4. An R, G, and B independently driven laser, an optical scanner for scanning a laser beam from the laser, and an LCD for injecting the scanned laser beam.
In an LCD projector including a panel and a projection lens that projects a laser beam from the LCD panel onto a screen, R which is selected and scanned in a specific array on the same optical axis,
The length parallel to the scanning direction of the G and B laser light is LCD
An LCD projector characterized in that it is shorter than the width of a light-shielding film in the panel and the length perpendicular to the scanning direction of the laser light is longer than the length perpendicular to the scanning direction of one pixel in the LCD panel.