Display device employing a field-sequential method

• US 6,762,743 B2
• Filed: 12/18/2001
• Issued: 07/13/2004
• Est. Priority Date: 07/16/2001
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Betsui, Keiichi, Yoshihara, Toshiaki, Makino, Tetsuya
• Primary Examiner(s): Porta, David
• Assistant Examiner(s): Lee, Patrick J.
• Application Number:
  US10/024,846
• Publication Number:
  US 20030010894A1
• Time in Patent Office: 938 Days
• Field of Search: 250/208.1, 250/205, 250/206, 250/214.R, 250/226, 250/214.LS, 250/214.D, 348/332, 348/742, 348/206, 348/521, 348/503, 348/455, 348/441, 348/459, 348/793, 345/593, 345/591, 345/10-12, 345/20, 345/22, 345/87-89, 345/101, 345/103, 345/213, 345/690-691, 353/46, 353/52, 362/510-511, 362/11, 362/13, 362/18, 362/2, 359/238, 359/240, 359/267, 359/298, 359/310
• US Class Current: 345/102
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2320/062 Adjustment of illumination source parameters
• CPC Class Codes: G09G 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• CPC Class Codes: G09G 2340/0435 Change or adaptation of the frame rate of the video stream
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: G09G 3/3651 using multistable liquid crystals, e.g. ferroelectric liquid crystals
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 47/00 Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant

Abstract

In a display device employing a field-sequential method, a judgement whether display data is motion picture data or still picture data is made, and the frame number per second is increased for the display of a motion picture during which color break easily occurs by the movement of the line of sight of a user, while the frame number is made smaller than that for the display of a motion picture, for the display of a still picture during which color break hardly occurs. Further, the temperature of a liquid crystal panel is detected, and the frame number per second is increased so as to reduce color break when the result of the detection is not lower than a predetermined temperature, while, the frame number is decreased so as to enable display at low temperature when the result of the detection is lower than the predetermined temperature.

Claims

1. A display device employing a field-sequential method, comprising:

a light source having a plurality of colors of emitted light;

a light emission switching unit for sequentially switching the plurality of colors of emitted light of said light source within one frame;

a light switching element for controlling an intensity of light from said light source for display;

a control unit for controlling synchronization of a light-emission timing of each color of emitted light of said light source and a switching of said light switching element; and

a frame number changing unit for changing a frame number per unit time;

wherein

said control unit controls the synchronization of the light emission timing and the switching in accordance with the frame number changed by said frame number changing unit, wherein

said frame number changing unit comprises a discrimination circuit for judging whether display data is motion picture data or still picture data, and a changing circuit for changing the frame number per unit time based on a result of the judgement by said discrimination circuit.

2. The display device of claim 1, wherein

when the display data is motion picture data, the frame number per unit time is increased compared with the frame number for still picture data.

3. The display device of claim 1, wherein

said light switching element is a liquid crystal display element.

4. The display device of claim 3, wherein

said liquid crystal display element includes a liquid crystal material having spontaneous polarization.

5. The display device of claim 3, wherein

said liquid crystal display element comprises an active element corresponding to each of a plurality of liquid crystal pixels.

6. The display device of claim 4, wherein

said liquid crystal display element comprises an active element corresponding to each of a plurality of liquid crystal pixels.

7. A field-sequential display method for displaying a color image by sequentially switching a plurality of colors of emitted light of a light source within one frame and by synchronizing a light-emission timing of each color of emitted light with a switching of a light switching element for controlling an intensity of light from said light source for display, comprising:

judging whether image data is motion picture data or still picture data; and

changing a frame number per unit time based on a result of the judgement; and

controlling the synchronization of the light-emission timing and the switching in accordance with the changed frame number.