JPH03250990A - Color liquid crystal projection type display device - Google Patents

Abstract

PURPOSE:To make a partition frame of picture elements not remarkable by deviating positions of 3 picture elements on a screen for forming one color by 1/3 pitch each and shifting the phase of 3 video signals fed to 3 liquid crystal panels in response to the deviation. CONSTITUTION:R, G and B liquid crystal panels 10-12 modulate an incident light in response to the video signal. Then the modulated blue and green lights are synthesized by a 1st dichroic mirror 13 and the synthesized light and the modulated red light are further synthesized by a 2nd dichroic mirror 14 for color synthesis and projected on a screen 16 via a projecting lens 15. In this case, since the green light G and the blue light B are deviated by 1/3 pitch of picture elements with respect to the red light R as a reference, three kinds of picture elements R, G, B are color-processed overlappingly to make the horizontal resolution thrice. Moreover, the borders of them are compensated mutually by the R, G, B picture elements and not remarkable.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention specifies light from a white light source into the three primary colors of red, blue, and green, and transmits and condenses the corresponding black and white images. , relates to a color liquid crystal projection display device that enlarges and projects onto a screen using a projection lens.

(B) Prior Art Projection televisions, which enlarge and project images using cold cathode tubes, have been known as projection display devices. With this cold cathode tube method, sufficient brightness cannot be obtained due to the limited brightness of the cold cathode tube.

Therefore, as shown in Japanese Unexamined Patent Application Publication No. 179723/1983, images of each color are reproduced by using liquid crystal panels as optical shutters and irradiating red light, blue light, and green light to each of the three liquid crystal panels. A system is being considered that combines and enlarges and projects the images. According to this method, the brightness of the light source can be easily increased, and an image with sufficient brightness can be obtained.

(C) Problems to be Solved by the Invention By the way, in the conventional method described above, it is necessary to combine each red, blue, and green image, so each pixel is aligned so that it is projected at the same position. .

Therefore, red, blue, and green pixels are superimposed on the screen at the same position as shown in FIG.

However, if this is done, there is a problem in that the image resolution can only be obtained at a maximum of each pixel pitch.

Furthermore, when the pixels are overlapped, the frame separating each pixel is easily visible and difficult to see.

(d) Means for Solving the Problems The present invention has been made in view of the above points, and includes a dichroic mirror for color separation that separates white light from a light source into three wavelength components, and a dichroic mirror for color separation that separates white light from a light source into three wavelength components. It is equipped with three liquid crystal panels that modulate wavelength components according to video signals, and a dichroic mirror for color synthesis that combines the output light of the three liquid crystal panels, and pixels are arranged on each of the three liquid crystal panels at a pitch of 1/3. Input the video signal with the phase corresponding to the
It is characterized in that the pixels of the output light of the three liquid crystal panels are synthesized by shifting them by 1/3 pitch on the screen.

(*) Effect According to the present invention, the positions of the three pixels on the screen for forming one color are shifted by 1/3 pitch, and the phases of the three video signals applied to the three liquid crystal panels are adjusted as described above. It is shifted according to the amount of shift. Therefore, the horizontal resolution can be tripled, and the pixel partition frames do not overlap, making them less noticeable.

Embodiment Figure 1 shows an embodiment of the present invention, in which (1) is a metal halide lamp serving as a light source, and (2) is a metal halide lamp that efficiently reflects and condenses the luminous flux from the metal halide lamp (1). (3) to (5) are first to third reflecting mirrors; (6) is a first dichroic that separates the white light from the first reflecting mirror (3) into blue light, red and green light; The dichroic mirror (7) separates the light incident from the first dichroic mirror (6) into red light and green light, and the second dichroic mirror (8) and (9) collect the incident light again. Fundensa lenses that emit light; (10) to (12) are R, G, and B liquid crystal panels that modulate incident light according to video signals; (13) and (14) are liquid crystal panels that modulate the output light of the liquid crystal panels; First and second dichroic mirrors for color synthesis; (15) is the second dichroic mirror;
14) is a projection lens that projects the output light onto a screen (16); (17) is a demodulator that generates demodulated R, G, and B primary color signals and a synchronization signal; (18) is a demodulator that
A control circuit (17) to which a synchronization signal is applied
9), a chroma circuit (20) to which an RM color signal is applied, the control circuit (19) and the chroma circuit (20);
) R liquid crystal panel control circuit consisting of an X-Y drive circuit (21) that generates a control signal for driving the liquid crystal panel according to the output signal of the R liquid crystal panel control circuit (22) and (23) This is a G and B liquid crystal panel control circuit having the same circuit configuration as circuit (18).

In Figure 1, light from a metal halide lamp (1) is transmitted to a first dichroic mirror (6) via a first reflecting mirror (3), where blue light is reflected and green light and red light are transmitted. be done. The blue light is reflected by the first reflection mirror 4), and its wavelength component is modulated by the B liquid crystal panel (12) according to the B primary color signal. On the other hand, the green light and red light transmitted through the first dichroic mirror (6) are
The light is further transmitted to the second dichroic mirror (7), where the green light is reflected and the red light is transmitted. The green light is modulated by the G liquid crystal panel (11), and the red light is modulated by the R liquid crystal panel (10). The modulated blue light and green light are combined by the first dichroic mirror (13) for color synthesis, and the combined light and the modulated red light are further combined by the second dichroic mirror (13) for color synthesis. 14) and projected onto a screen (16) via a projection lens (15).

Here, R, G and B liquid crystal panels (10) to (12)
), each corresponding pixel is projected onto the screen (16) as shown in FIG. In Figure 3, the solid line represents red light (R), the dotted line represents green light (G), and the dashed line represents blue light (G).
B) is shown. As shown in Figure 3, when red light (R) is used as a reference, green light (G) and blue light (B)
/3 pitches at a time. Therefore, in the hatched area in FIG. 3, the three types of pixels R, G, and B overlap and can be colored, making it possible to triple the horizontal resolution.

Further, the TPT portions, transparent electrode lead wire portions, and mutual boundary portions of each pixel are compensated for by each R, G, and B pixel and are made inconspicuous. Various methods can be considered for shifting the R, G, and B pixels on the screen 16). For example, the pixels themselves on each liquid crystal panel may be shifted by 1/3 pitch compared to conventional ones, or each liquid crystal panel as a whole may be moved.

Now, with the method described above, it is possible to significantly increase the resolution compared to the conventional method, but when shifting the position of each pixel on the screen, it is necessary to shift the video signal applied to each liquid crystal panel accordingly. be. By doing so, the resolution can be increased.

In FIG. 1, the demodulated R primary color signal and synchronization signal from the demodulator (17) are transmitted to the R liquid crystal panel control circuit (17).
8) is applied. The control circuit (19) creates various timing signals according to the synchronization signal, and
is applied to the drive circuit (21). Further, the R primary color signal is applied to the XY drive circuit (21) after being subjected to signal processing such as amplification in the chroma circuit (20). The X-Y drive circuit (21) directly drives the R liquid hole panel (lO) and generates two control signals for horizontal scanning and vertical scanning. Then, pixels of the liquid crystal panel are driven according to the two control signals, and the incident light is modulated. The control signal for horizontal scanning includes the start timing of horizontal scanning, that is, the phase information of the horizontal video signal, and by adjusting this, the above-mentioned phase operation becomes possible.

For example, to perform the phase operation corresponding to the one shown in Fig. 3, the phase amount of the horizontal scanning control signal generated from the R liquid crystal panel control circuit (18) is set to 0 degrees, and the 22> may be set to α degrees, and that of the B liquid crystal panel control circuit (23) may be set to 2α degrees. By doing so, it is possible to match the video contents of the three superimposed pixels.

FIG. 4 shows a specific circuit example of the X-Y drive circuit (21) in FIG. 1, where (24) is a shift register (25),
Sample and hold circuit (26) and output buffer (27)
) is a horizontal scanning circuit, and (28) is a vertical scanning circuit.

In FIG. 4, a clock signal for horizontal scanning is applied to the terminal (29), and a start signal for horizontal scanning arrives at the terminal (30) in one horizontal period. In response to the start signal, the shift register (25) starts receiving the clock signal and sequentially generates outputs. In response to the output, the sample and hold circuit (26) sequentially samples and holds one scanning line worth of video signals from the terminal (31). The output of the sample and hold circuit (26) is sequentially applied to the output buffer (27) and
2), the output buffers (27) are simultaneously turned on during the horizontal retrace period, and the video signals for one horizontal scan are sent to the drain bus (33) of the R liquid crystal panel 10).
).

On the other hand, the vertical scanning circuit (28) performs one scan per horizontal scanning period.
A gate busk 34> for a row is selected, and a video signal is applied to the liquid crystal cell of each pixel in the selected row. Then, reading this sequentially can be repeated every field. Therefore, by changing the phase of the start signal from the terminal (30), it is possible to shift the horizontal phase of the video signal applied to the liquid crystal panel. In the example shown in Figure 4, the delay circuit (3
5) is used to perform phase adjustment.

(G) Effects of the Invention As described above, according to the present invention, the light from three liquid crystal panels is synthesized on the screen by 1/3 pitch at a time, and the phase of the video signal applied to the three liquid crystal panels is Since it is shifted in accordance with the amount of shift, it is possible to significantly improve the resolution. It also has the advantage that almost no pixel structure appears on the screen.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a characteristic diagram for explaining a conventional color liquid crystal projection display device, and FIG. 3 is for explaining FIG. The characteristic diagram and FIG. 4 are circuit diagrams showing a specific example of the X-Y drive circuit 21) in FIG. 1. (6)(7)...First and second clock mirrors, (10) to (12)...LCD panels for R, G and B, (13)(14)...For color synthesis the first and second
dichroic mirror

Claims (2)

[Claims] (1) A dichroic mirror for color separation that separates white light from a light source into three wavelength components, and a dichroic mirror that modulates the separated wavelength components according to a video signal.
It is equipped with two liquid crystal panels and a dichroic mirror for color synthesis that combines the output lights of the three liquid crystal panels, and transmits video signals of phases corresponding to pixels shifted by 1/3 pitch to the three liquid crystal panels. A color liquid crystal projection display device characterized in that the pixels of the output light of the three liquid crystal panels are shifted by 1/3 pitch on a screen and synthesized. (2) The color liquid crystal projection display device according to claim 1, wherein the pixels of the output light of the three liquid crystal panels are shifted horizontally by 1/3 pitch on the screen and synthesized.