Display

• US 20020149576A1
• Filed: 03/28/2002
• Published: 10/17/2002
• Est. Priority Date: 03/30/2001
• Status: Active Grant

• Current Assignee: Japan Display Central Incorporated (Japan Display Incorporated)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Okada, Takashi, Tanaka, Yukio, Kimura, Masanori, Kumagawa, Katsuhiko
• Granted Patent: US 6,965,367 B2
• Time in Patent Office: Days
• US Class Current: 345/204
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2310/0237 Switching ON and OFF the backlight within one frame
• CPC Class Codes: G09G 2310/024 Scrolling of light from the illumination source over the display in combination with the scanning of the display screen
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

Disclosed is a display capable of improving uniformity of luminance and chroma in a plane of a display panel. When point at which the light source is turned ON is represented by T1, transmittance in a display region onto which the video signals are being written at the point T1 is represented by M1. point at which the light source is turned OFF is represented by T2, transmittance in the display region onto which the video signals are being written at point T2 is represented by M2, a maximum value of the transmittance in the display region of the light modulation element in a period during which the light source is ON is represented by M0, and the write period is represented by Twrite, the illuminating device control portion is adapted to control the illuminating device so as to satisfy a formula given by [|M2−M1|Twrite]/[M0(T2−T1)]≦0.92.

Claims

1. A display comprising:

a light modulation element including light modulation medium interposed between a pair of opposed substrates and having a plurality of pixels for displaying an image;

an illuminating device having a light source;

a drive portion for driving the light modulation medium by sequentially repeating writing and erasing of video signals for each pixel group to thereby change transmittance of light emitted from the light source in the light modulation element; and

an illuminating device control portion for controlling the illuminating device to cause the light source to be turned ON in the course of rising of transmittance in a pixel included in a pixel group onto which the video signals are being written at substantially intermediate time in a write period during which the video signals are written and the light source to be turned OFF in the course of falling of the transmittance in the pixel.

2. The display according to claim 1, wherein the illuminating device control portion is adapted to control the illuminating device to cause the light source to be turned ON in the course of rising of transmittance in a pixel included in a pixel group onto which the video signals are being written substantially at start point of the write period and the light source to be turned OFF in the course of falling of transmittance in a pixel included in a pixel group onto which the video signals are being written substantially at completion point of the write period.

3. The display according to claim 1, wherein when point at which the light source is turned ON is represented by T1, transmittance in display region onto which the video signals are being written at the point T1 is represented by M1, point at which the light source is turned OFF is represented by T2, transmittance in display region onto which the video signals are being written at point T2 is represented by M2, a maximum value of the transmittance in the display region of the light modulation element in a period during which the light source is ON is represented by M0, and the write period is represented by Twrite, the illuminating device control portion is adapted to control the illuminating device so as to satisfy a formula given by [|M2−

M1|Twrite]/[M0(T2−

T1)]≦

0.92.

4. The display according to claim 3, wherein when response time of the liquid crystal is represented by Tlc, the illuminating device control portion is adapted to control the illuminating device so as to satisfy Tlc≧

Twrite.

5. The display according to claim 1, wherein one of the pair of substrates is an array substrate having a plurality of gate lines and source lines arranged so as to cross each other;

pixel electrodes respectively provided as corresponding to points at which the plurality of gate lines and the plurality of source lines cross each other;

a plurality of switching devices respectively provided as corresponding to the pixel electrodes, for switching between a conductive state and a non-conductive state between the pixel electrodes and the source lines in accordance with a drive signal supplied through the gate lines, and

the other of the pair of substrates is an opposing substrate having a counter electrode disposed opposite to the array substrate.

6. The display according to claim 1, further comprising:

a temperature sensor for measuring temperature of a vicinity of the light modulation element, wherein the illuminating device control portion is adapted to control the illuminating device to cause the light source to be turned ON/OFF according to measurement obtained by the temperature sensor.

7. The display according to claim 1, further comprising a receiving portion for receiving an input for setting of ON timing of the light source, wherein the illuminating device control portion is adapted to control the illuminating device to cause the light source to be turned ON/OFF according to the setting indicated by the input received by the receiving portion.

8. The display according to claim 1, wherein the light modulation medium is liquid crystal.

9. The display according to claim 8, wherein the liquid crystal is OCB-mode liquid crystal.

10. The display according to claim 1, wherein the light source is light-emitting diode.

11. The display according to claim 1, wherein the light source is electroluminescence light-emitting element.

12. The display according to claim 1, wherein the illuminating device has a light source for emitting lights of different prisms,

one frame period of the video signals is composed of a plurality of sub-frame periods, and

the illuminating device control portion is adapted to control the illuminating device to cause the light source for emitting light of a specified prism in the course of rising of transmittance in the pixel included in the pixel group onto which the video signals are being written at substantially intermediate time in the write period and the light source to be turned OFF in the course of falling of the transmittance in the pixel in each sub-frame period.

13. The display according to claim 1, wherein one of the pate of substrates has color filters of red, blue, and green, and

the illuminating device control portion is adapted to control the illuminating device to cause the light source to be turned ON in the course of rising of the transmittance in the pixel included in the pixel group onto which the video signals are being written at substantially intermediate time in the write period and the light source to be turned OFF in the course of falling of the transmittance in the pixel in each frame period of the video signals.

14. A cellular telephone comprising:

the display according to claim 1, the cellular telephone belong adapted to output video signals to the display.

15. A portable terminal comprising:

the display according to claim 1, the portable terminal being adapted to output video signals to the display.