DISPLAY CONTROLLER, DISPLAY DEVICE, DISPLAY SYSTEM, AND METHOD FOR CONTROLLING DISPLAY DEVICE

• US 20090237391A1
• Filed: 03/27/2007
• Published: 09/24/2009
• Est. Priority Date: 07/31/2006
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Miyamoto, Takuji, Murai, Atsuhito, Yanagi, Toshihiro
• Granted Patent: US 8,692,822 B2
• Time in Patent Office: Days
• US Class Current: 345/213
• CPC Class Codes: G09G 2310/0283 Arrangement of drivers for different directions of scanning
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2340/0435 Change or adaptation of the frame rate of the video stream
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: G09G 5/18 Timing circuits for raster scan displays specially adapted for television H04N ; synchronisation between the display unit and other display units, videodisc player G09G5/12

Abstract

A display controller is capable of changing a refresh rate, indicative of how often a screen displayed on a display device having a plurality of pixels is switched, between a low refresh rate of 40 Hz and a normal refresh rate of 60 Hz and generates (i) a dot clock (reference clock) serving as a timing signal indicative of a timing of operation in the display device, (ii) video data indicative of an image to be displayed on the screen, (iii) Hsync for defining a horizontal period of a display on the screen, and (vi) Vsync for defining a vertical period of the display on the screen, so as to supply the dot clock, the video data, Hsync, and Vsync to the display device, wherein the display controller includes a dot clock generation circuit for generating the reference clock whose frequency is constant without depending on a change of the refresh rate. This makes it possible to provide the display controller which can suppress occurrence of noise also in switching the refresh rate and which does not allow any screen derangement which is caused by the noise.

Claims

1-30. -30. (canceled)

31. A display controller, which is capable of changing a refresh rate indicative of how often a screen displayed on a display device having plural pixels is switched and which generates (i) a dot clock serving as a timing signal indicative of a timing of operation in the display device, (ii) video data indicative of an image to be displayed on the screen, (iii) a horizontal synchronization signal for defining a horizontal period of a display on the screen, and (vi) a vertical synchronization signal for defining a vertical period of the display on the screen, so as to supply the dot clock, the video data, the horizontal synchronization signal, and the vertical synchronization signal to the display device,

said display controller comprising a dot clock generation device to generate the dot clock whose frequency is constant without depending on a change of the refresh rate.

33. The display controller as set forth in claim 31, comprising a horizontal synchronization signal generation device which receives the dot clock from the dot clock generation device and counts the dot clock so as to generate the horizontal synchronization signal, wherein

the horizontal synchronization signal generation device fixes a count number of the dot clock, which is counted in generating a single horizontal synchronization signal, without depending on the change of the refresh rate.

34. The display controller as set forth in claim 31, further comprising a vertical synchronization signal generation device which counts a cycle of the horizontal synchronization signal so as to generate the vertical synchronization signal, wherein

the vertical synchronization signal generation device changes a count number of the cycle of the horizontal synchronization signal, which is counted in generating a single vertical synchronization signal, in accordance with the change of the refresh rate.

35. The display controller as set forth in claim 31, comprising a power control signal generation device to generate a power control signal which controls operation of a power source circuit and an analog circuit included in the display device, wherein

the power control signal causes the power source circuit and the analog circuit to be OFF in at least part of an inactive period in which the video data is not supplied to the display device, said video data being supplied to the display device in an active period.

36. The display controller as set forth in claim 35, wherein the power control signal generation device uses the power control signal so as to cause the circuits to be ON in starting preparation for writing of the video data into the pixels and so as to cause the circuits having been turned ON to be OFF in finishing the writing of the video data into the pixels.

37. The display controller as set forth in claim 35, wherein:

in case of supplying the dot clock, the video data, the horizontal synchronization signal, and the vertical synchronization signal to the display device based on a differential transfer method, the power control signal is included in data used in the differential transfer method.

38. A display device, controlled by the display controller as set forth in claim 31.

32. A display controller, which is capable of changing a refresh rate indicative of how often a screen displayed on a display device having plural pixels is switched and which generates (i) a dot clock serving as a timing signal indicative of a timing of operation in the display device, (ii) video data indicative of an image to be displayed on the screen, (iii) a horizontal synchronization signal for defining a horizontal period of a display on the screen, and (vi) a vertical synchronization signal for defining a vertical period of the display on the screen, so as to supply the dot clock, the video data, the horizontal synchronization signal, and the vertical synchronization signal to the display device,

said display controller comprising a horizontal synchronization signal generation device to generate the horizontal synchronization signal whose cycle is constant without depending on a change of the refresh rate.

39. A method for controlling a display device, which allows a change of a refresh rate indicative of how often a screen displayed on a display device having plural pixels is switched and which allows generation of (i) a dot clock serving as a timing signal indicative of a timing of operation in the display device, (ii) video data indicative of an image to be displayed on the screen, (iii) a horizontal synchronization signal for defining a horizontal period of a display on the screen, and (vi) a vertical synchronization signal for defining a vertical period of the display on the screen, so as to supply the dot clock, the video data, the horizontal synchronization signal, and the vertical synchronization signal to the display device, wherein

a frequency of the dot clock is made constant without depending on the change of the refresh rate.