JP3069793B2 - Projection type liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] A projection-type liquid crystal display device that performs color display by projecting a moving image is provided. The object of the present invention is to reduce the number of liquid crystal panels for display, thereby reducing costs and simplifying adjustment. The projection-type liquid crystal display device is designed to change the white light of the light source to red, green,
A light separating means for separating the light into blue light, a first liquid crystal panel for modulating the separated one color light by a data signal and transmitting the light, and an optical shutter device provided in an optical path of the remaining two colors of light, respectively. Optical path correcting means for matching the optical paths of the light emitted from the optical shutter device, a second liquid crystal panel which modulates and transmits two colors of light by a data signal, and light emitted from the first and second liquid crystal panels. Means for synthesizing light, and a projection lens, and normal data writing and holding are performed on the first liquid crystal panel during one frame period.
Of the remaining two colors in the first half period, and the writing and holding of the remaining one color in the second half period. Driving means for opening and closing the optical shutter in accordance with the operation.

[Industrial applications]

The present invention relates to a projection type liquid crystal display device, and more particularly, to a projection type liquid crystal display device which projects light on a liquid crystal panel to display a moving image in color.

In recent years, there has been a demand to enjoy the atmosphere of images and sounds in movie theaters even at home, and the size of televisions has become larger, and the number of speakers that provide a sense of reality tends to increase. For this reason, projection type televisions called projection televisions are becoming widespread in place of cathode ray tubes whose mass production size is limited. The projection type television includes a rear projection type in which an image is projected on the rear side of the screen and a front projection type in which an image is projected on the screen and the front side. The front projection type can increase the screen size.

A projection tube has been used for a light modulation portion of a projection display device used for a display device such as a front projection television or a personal computer. Projected on a single LCD panel,
A projection-type liquid crystal display device that combines emitted light to create a color image is in a practical stage. However, the projection type liquid crystal display device is expensive and difficult to adjust, and a low cost and easy adjustment type projection liquid crystal display device is desired.

[Prior Art] FIG. 5 shows a configuration of a conventional projection type liquid crystal display device. Light from light source 50 is two dichroic mirrors
The light is separated into red, green, and blue lights R, G, and B by 51 and 52. After the light path is changed by the mirror 54, the light B is light-modulated by the liquid crystal panel 55 to reach the dichroic prism 59, and the light G is light-modulated by the liquid crystal panel 56 to reach the dichroic prism 59.
The light R is changed in optical path by mirrors 53 and 57,
Then, the light is modulated to reach the dichroic prism 59. The three colors of light B, G, and R are combined by the dichroic prism 59 and pass through the projection lens 60 to form an image on a screen.

[Problems to be solved by the invention]

However, the conventional projection type liquid crystal display device configured as described above requires three liquid crystal panels to perform color display, and has a problem of high cost. Further, in the conventional apparatus, three screens must be accurately synthesized on a screen using a dichroic prism, and this adjustment is not easy. For this reason, there is also a problem that the yield of products is poor.

An object of the present invention is to provide a projection type liquid crystal display device which can solve the problems of the conventional projection type liquid crystal display device, reduce the number of liquid crystal panels for display, reduce cost and simplify adjustment. It is in.

[Means for solving the problem]

FIG. 1 shows the configuration of a projection type liquid crystal display device of the present invention which achieves the above object. In the drawing, a light separating means 2 separates white light of a light source 1 into red, green and blue light, and a first liquid crystal panel 3 modulates the separated one color light by a data signal and transmits the modulated light. Optical shutter devices 4 and 5 are provided in the optical paths of the remaining two colors of light, respectively.
The optical path correcting means 6 makes the optical paths of the light emitted from the light sources 4 and 5 coincide. The second liquid crystal panel 7 modulates and transmits the two colors of light having the same optical path with the data signal, and the light combining means 8 combines the light emitted from the first and second liquid crystal panels 3 and 7 and projects the combined light. The combined light is projected by the lens 9. In the above-described configuration, the driving unit 10 causes the first liquid crystal panel 3 to perform normal data writing and holding in one frame period, and causes the second liquid crystal panel 7 to perform normal data writing and holding. During the period, one of the remaining two colors is written and held, and during the latter half the other color is written and held, and the optical shutters 4 and 5 are operated in accordance with the operation of each color. Open and close.

[Action]

According to the projection type liquid crystal display device of the present invention, one of the two liquid crystal panels displays one of the red screen display, the green screen display, and the blue screen display as usual, and the other one of the two liquid crystal panels performs the other display. In the liquid crystal panel, display of the other two colors is sequentially selected for each half frame, and a signal corresponding to the light is written to the liquid crystal panel. Then, the display of red, green, and blue is completed in one frame to complete one screen. When displaying a television signal, the control section stores input signals of two colors for performing time-division display for one frame for one screen, and reads two signals stored for each half frame period when writing to the panel. And written sequentially to the panel.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 shows the configuration of one embodiment of the projection type liquid crystal display device of the present invention. In the figure, white light from a light source 20 is red by three dichroic mirrors 21, 22, and 23,
It is separated into green, blue light R, G, B. Of these lights R, G, B, in this embodiment, for example, after the green light G is directly incident on the display liquid crystal panel 24 and light-modulated by the data input to the liquid crystal panel 24, the dichroic prism
The light is projected from a projection lens 15 onto a screen (not shown) through 30. The other two colors, here red and blue light R and B, are incident on optical shutters 26 and 27 composed of ferroelectric liquid crystal panels, and are reflected and displayed on mirrors 28 and 29 only when optical shutters 26 and 27 are opened. Incident on the liquid crystal panel 25. After being light-modulated by data input to the liquid crystal panel 25, the light is projected from the projection lens 15 through a dichroic prism 30 onto a screen (not shown).

FIG. 3 is a timing chart showing the operation of the apparatus shown in FIG. In one frame period, the data for the green light G is written to the liquid crystal panel 24 as in the related art, and the display is performed. Light R of red and blue, for of B, the 1/2 frame period of the first half of one frame in this embodiment, data of red light R is written to the liquid crystal panel 25 during the first time t _1, 1 / 2 for the remainder of the frame period to hold the data is performed in 1/2 frame period in the second half, the data of the blue light B is written into the liquid crystal panel 25 during the first time t _2, 1 / This data is held during the remaining two frame periods. Therefore, the light shutter 26 is opened only the first period excluding the time t ₁ of the first half of one frame period, the optical shutter 27 and opens only the first period excluding the time t ₂ of the second half of one frame period.

In this way, it is possible to display red and blue lights R and B using one liquid crystal panel 25 by time-dividing one frame period. The optical shutters 26 and 27
Although the device shown in FIG. 2 uses a ferroelectric liquid crystal panel, it may use a mechanical shutter. In this embodiment, the order is green, red, and blue, but this combination may be arbitrary.

FIG. 4 shows a configuration of a control device when a television signal (video signal) is displayed using the device configured as shown in FIG. In the figure, liquid crystal panels 24 and 25 are data drivers 241 and 25 for driving data electrodes, respectively.
1, and scan drivers 242 and 252 for driving scan electrodes. In the apparatus shown in FIG. 2, data of two kinds of colors is transmitted to the liquid crystal panel 25 during one frame.
, The television signal cannot be displayed in real time.

Therefore, in the embodiment shown in FIG. 4, the R data frame memory 41, the B data frame memory 42, and the green light which can store the red and blue light R and B data in one frame period. A delay circuit 43 for delaying G data by one frame period is provided. Then, in a certain frame period, the red and blue light R and B data transmitted during the frame period are respectively stored in the R data frame memory 41 and the B data frame memory.
The green light G data stored at 42 is delayed by one frame period. In the next frame period, green light G data is output from the delay circuit 43 over one frame period,
Red and blue light R, B is the data and the R data frame memory 41 first half and the second half of 1 in the frame at the timing shown in FIG. 3, the time t ₁ is read from the B data frame memory 42, It is written in the liquid crystal panel 25 during the period t _2.

In addition, instead of the delay circuit 43, a G data frame memory is also prepared for the green light G data, and transmitted in a certain frame period in the same frame period as the red and blue light R and G data. The received green light G data is stored in the G data frame memory, and during the next frame period, the green light G data is output from the G data frame memory over one frame period. It may be configured as follows.

〔The invention's effect〕

As described above, according to the present invention, in the projection type liquid crystal display device, the number of panels can be reduced, the number of adjustment points can be reduced, and the size and cost of the device can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the principle of a projection type liquid crystal display device according to the present invention, FIG. 2 is a block diagram showing an embodiment of a projection type liquid crystal display device according to the present invention, and FIG. 3 shows the operation of the device shown in FIG. FIG. 4 is a diagram showing a configuration of a control circuit when a television signal is displayed using the device of FIG. 2, and FIG. 5 is a diagram showing a configuration of a conventional projection type liquid crystal display device. 15 Projection lens, 20 Light source, 21, 22 Dichroic mirror, 23, 28, 29 Mirror, 24, 25 Liquid crystal panel for display, 26, 27 Optical shutter, 30 Dichroic Prism, 40: LCD panel control circuit, 41: Frame memory for R data, 42: Frame memory for B data, 43: Delay circuit or frame memory for G data.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kazuhiro Takahara 1015 Uedanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu Limited (56) References JP-A-61-102893 (JP, A) JP-A-63-121379 (JP, A) JP-A-63-195698 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 9/31 G02F 1/157 G03B 21/00

Claims (3)

(57) [Claims] 1. A light separating means (2) for separating white light of a light source (1) into red, green and blue light, and a first liquid crystal panel for transmitting the separated one color light by modulating it with a data signal. (3) The optical paths of the light emitted from the optical shutter devices (4) and (5) coincide with the optical shutter devices (4) and (5) provided in the optical paths of the remaining two colors of light, respectively. Optical path correcting means (6), a second liquid crystal panel (7) that modulates and transmits two colors of light by a data signal, and light emitted from the first and second liquid crystal panels (3) and (7). (8) and projection lens (9)
During the one frame period, normal data writing and holding are performed on the first liquid crystal panel (3), and the remaining two data are written on the second liquid crystal panel (7) during the first half period. One of the colors is written and held, and the remaining one is written and held in the latter half of the period, and the optical shutters (4) and (5) are opened and closed according to the operation of each color. A projection type liquid crystal display device comprising: 2. The driving means (10) includes a memory circuit for storing a screen signal of one frame period of data to be written to the second liquid crystal panel (7), and stores data to the first liquid crystal panel (3). While delaying by one frame period, data to the second liquid crystal panel (7) is taken into the memory circuit, and in the next frame period, the second liquid crystal panel (7) is transferred to the second liquid crystal panel (7) based on the data of the memory circuit. 2. The projection type liquid crystal display device according to claim 1, wherein writing is performed once. 3. The driving means (10) includes a memory circuit for storing a screen signal of one frame period of write data for all colors, fetches display data into each memory circuit in a first frame period, and In the frame period, data writing and holding are performed once in the first liquid crystal panel (3) within one frame period, and the first half of the one frame period is performed in the second liquid crystal panel (7). 2. The projection type liquid crystal display device according to claim 1, wherein data writing and holding are performed twice, once in each of the first and second half periods.