SEMI-TRANSMISSIVE LIQUID CRYSTAL DISPLAY DEVICE AND PORTABLE TERMINAL DEVICE

• US 20070146261A1
• Filed: 12/21/2006
• Published: 06/28/2007
• Est. Priority Date: 12/22/2005
• Status: Active Grant

• Current Assignee: NLT Technologies, Ltd.
• Original Assignee: NLT Technologies, Ltd.
• Inventors: Sumiyoshi, Ken, Okumura, Hiroshi, Matsushima, Jin
• Granted Patent: US 8,558,770 B2
• Time in Patent Office: Days
• US Class Current: 345/87
• CPC Class Codes: G02F 1/1323 Arrangements for providing a switchable viewing angle
• CPC Class Codes: G09G 2310/0297 Special arrangements with multiplexing or demultiplexing of display data in the drivers for data electrodes, in a pre-processing circuitry delivering display data to said drivers or in the matrix panel, e.g. multiplexing plural data signals to one D/A converter or demultiplexing the D/A converter output to multiple columns
• CPC Class Codes: G09G 2320/0209 Crosstalk reduction, i.e. to reduce direct or indirect influences of signals directed to a certain pixel of the displayed image on other pixels of said image, inclusive of influences affecting pixels in different frames or fields or sub-images which constitute a same image, e.g. left and right images of a stereoscopic display
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 3/3688 suitable for active matrices only

Abstract

A liquid crystal display element accommodates a reflective portion provided with a concavo-convex reflecting pixel electrode for reflecting incident light from the display face side and displaying information, and a transmissive portion provided with a transmissive pixel electrode for transmitting light that is output from the backlight. The voltages applied to the reflective portion and the transmissive portion are controlled independently. The reflective portion and the transmissive portion have wide viewing angle characteristics. In a wide viewing angle region greater than a certain angle, the luminance of the reflective portion is greater than the luminance of the transmissive portion, whereas in other angle regions the luminance of the transmissive portion is greater than the luminance of the reflective portion. In a wide viewing field mode, the reflective portion and transmissive portion both perform normal display, whereas in the narrow viewing field mode, the transmissive portion performs normal display, while the reflective portion performs cancelling data display, thereby rendering unviewable the display content of the transmissive portion from beyond a certain viewing angle. It is thus possible to provide a semi-transmissive liquid crystal display device and a portable terminal device switchable between a narrow viewing field mode and a wide viewing field mode.

Claims

1. A semi-transmissive liquid crystal display device comprising:

a liquid crystal panel provided with a liquid crystal layer between two substrates having electrodes formed thereon;

a backlight for outputting light to the liquid crystal panel; and

a controller for controlling a voltage applied to said liquid crystal layer;

wherein

each pixel of said liquid crystal panel individually has a reflective portion for reflecting light incident from the display screen side, and a transmissive portion for transmitting and displaying light that is output by said backlight;

both said reflective portion and said transmissive portion have wide viewing angle characteristics, and have luminance/viewing angle characteristics such that in a wide viewing angle region greater than a certain angle the luminance of said reflective portion is greater than the luminance of said transmissive portion; and

said controller controls, independently for said reflective portion and said transmissive portion, the voltage applied to said liquid crystal layer, and switches a viewing angle between a wide viewing field mode and a narrow viewing field mode by performing control so that, in the wide viewing field mode said reflective portion performs normal display or dark display while said transmissive portion performs normal display, whereas in the narrow viewing field mode said reflective portion performs cancelling data display while said transmissive portion performs normal display.

4. The semi-transmissive liquid crystal display device according to claim 1, wherein in said narrow viewing field mode, an image pattern is displayed by performing normal display or dark display in the reflective portion that makes up part of the pixel, without carrying out cancelling data display.

8. The semi-transmissive liquid crystal display device according to claim 1, in other angle regions the luminance of said transmissive portion is greater than the luminance of said reflective portion.

9. The semi-transmissive liquid crystal display device according to claim 1, wherein the voltage applied to the liquid crystal layer in said reflective portion and in said transmissive portion is independently controlled by separately providing a reflection pixel electrode formed in said reflective portion, and a transmission pixel electrode formed in said transmissive portion, and connecting the electrodes to mutually different TFTs.

12. The semi-transmissive liquid crystal display device according to claim 1, wherein the voltage applied to the liquid crystal layer in said reflective portion and in said transmissive portion is independently controlled by separately providing a COM electrode formed in said reflective portion and a COM electrode formed in said transmissive portion.

20. The semi-transmissive liquid crystal display device according to claim 1, wherein said cancelling data is a display using white luminance, intermediate luminance, or false color light.

21. The semi-transmissive liquid crystal display device according to claim 1 having a front light on the side facing the observer.

22. The semi-transmissive liquid crystal display device according to claim 1, comprising a louver for use in regulating the direction of exiting light incident from the backlight.

23. The semi-transmissive liquid crystal display device according to claim 1, comprising a transmitting/scattering switch element switchable between a state of transmitting and a state of scattering incident light.

24. A portable terminal device comprising the semi-transmissive liquid crystal display device according to claim 1.

2. A semi-transmissive liquid crystal display device comprising:

a liquid crystal panel provided with a liquid crystal layer between two substrates having electrodes formed thereon;

a backlight for outputting light to the liquid crystal panel; and

a controller for controlling a voltage applied to said liquid crystal layer;

wherein

each pixel of said liquid crystal panel individually has a reflective portion for reflecting light incident from the display screen side, and a transmissive portion for transmitting and displaying light that is output by said backlight;

each of said reflective portion and said transmissive portion has wide viewing angle characteristics and narrow viewing angle characteristics, respectively; and

said controller controls, independently for said reflective portion and said transmissive portion, the voltage applied to said liquid crystal layer, and switches a viewing angle between a wide viewing field mode and a narrow viewing field mode by performing control so that in the wide viewing field mode said reflective portion performs normal display while said transmissive portion performs normal display, whereas in the narrow viewing field mode said reflective portion performs dark display while said transmissive portion performs normal display.

5. The semi-transmissive liquid crystal display device according to claim 2, wherein in said narrow viewing field mode, an image pattern is displayed by performing normal display in the reflective portion that makes up part of the pixel, without carrying out dark display.

10. The semi-transmissive liquid crystal display device according to claim 2, wherein the voltage applied to the liquid crystal layer in said reflective portion and in said transmissive portion is independently controlled by separately providing a reflection pixel electrode formed in said reflective portion, and a transmission pixel electrode formed in said transmissive portion, and connecting the electrodes to mutually different TFTS.

13. The semi-transmissive liquid crystal display device according to claim 2, wherein the voltage applied to the liquid crystal layer in said reflective portion and in said transmissive portion is independently controlled by separately providing a COM electrode formed in said reflective portion and a COM electrode formed in said transmissive portion.

25. A portable terminal device comprising the semi-transmissive liquid crystal display device according to claim 2.

3. A semi-transmissive liquid crystal display device comprising:

a liquid crystal panel provided with a liquid crystal layer between two substrates having electrodes formed thereon;

a backlight for outputting light to the liquid crystal panel; and

a controller for controlling a voltage applied to said liquid crystal layer;

wherein

each pixel of said liquid crystal panel individually has a reflective portion for reflecting light incident from the display screen side, and a transmissive portion for transmitting and displaying light that is output by said backlight;

each of said reflective portion and said transmissive portion has wide viewing angle characteristics and narrow viewing angle characteristics, respectively; and

said controller controls, independently for said reflective portion and said transmissive portion, the voltage applied to said liquid crystal layer, and switches a viewing angle between a wide viewing field mode and a narrow viewing field mode by performing control so that in the wide viewing field mode said reflective portion performs normal display while said transmissive portion performs normal display, whereas in the narrow viewing field mode said reflective portion performs normal display while said transmissive portion performs dark display.

6. The semi-transmissive liquid crystal display device according to claim 3, wherein in said narrow viewing field mode, an image pattern is displayed by performing normal display in the transmissive portion that makes up part of the pixel, without carrying out dark display.

7. The semi-transmissive liquid crystal display device according to claim 6, wherein the display of said image pattern in said narrow viewing field mode varies spatially, temporally, or spatiotemporally.

11. The semi-transmissive liquid crystal display device according to claim 3, wherein the voltage applied to the liquid crystal layer in said reflective portion and in said transmissive portion is independently controlled by separately providing a reflection pixel electrode formed in said reflective portion, and a transmission pixel electrode formed in said transmissive portion, and connecting the electrodes to mutually different TFTs.

14. The semi-transmissive liquid crystal display device according to claim 3, wherein the voltage applied to the liquid crystal layer in said reflective portion and in said transmissive portion is independently controlled by separately providing a COM electrode formed in said reflective portion and a COM electrode formed in said transmissive portion.

26. A portable terminal device comprising the semi-transmissive liquid crystal display device according to claim 3.

15. A semi-transmissive liquid crystal display device comprising:

a liquid crystal panel provided with a liquid crystal layer between two substrates having electrodes formed thereon;

a backlight for outputting light to the liquid crystal panel;

a reflective polarizing plate or a semi-transmissive polarizing plate on the substrate disposed toward said backlight, on the side of the substrate that faces the backlight; and

a controller for controlling a voltage applied to said liquid crystal layer;

wherein

each pixel of said liquid crystal panel individually has a first display portion and a second display portion;

both said first display portion and said second display portion have wide viewing angle characteristics, and have luminance/viewing angle characteristics such that in a wide viewing angle region greater than a certain angle the luminance of said first display portion is greater than the luminance of said second display portion, whereas in other angle regions the luminance of said second display portion is greater than the luminance of said first display portion; and

said controller controls, independently for said first display portion and said second display portion, the voltage applied to said liquid crystal layer, and switches a viewing angle between a wide viewing field mode and a narrow viewing field mode by performing control so that in the wide viewing field mode said first display portion performs normal display or dark display while said second display portion performs normal display, whereas in the narrow viewing field mode said first display portion performs cancelling data display while said second display portion performs normal display.

16. The semi-transmissive liquid crystal display device according to claim 15, wherein in said narrow viewing field mode, an image pattern is displayed by performing normal display or dark display in the first display portion that makes up part of the pixel, without carrying out cancelling data display.

17. The semi-transmissive liquid crystal display device according to claim 16, wherein the display of said image pattern in said narrow viewing field mode varies spatially, temporally, or spatiotemporally.

18. The semi-transmissive liquid crystal display device according to claim 15, wherein the voltage applied to the liquid crystal layer in said first display portion and in said second display portion is independently controlled by providing a first pixel electrode formed in said first display portion, and a second pixel electrode formed in said second display portion, and connecting the electrodes to mutually different TFTs.

19. The semi-transmissive liquid crystal display device according to claim 15, wherein the voltage applied to the liquid crystal layer in said first display portion and in said second display portion is independently controlled by separately providing a COM electrode formed in said first display portion and a COM electrode formed in said second display portion.