Liquid crystal display apparatus

• US 7,113,163 B2
• Filed: 06/26/2001
• Issued: 09/26/2006
• Est. Priority Date: 09/08/2000
• Status: Expired due to Term

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Hitachi, Ltd., Hitachi Video And Information System Inc.
• Inventors: Maeda, Takeshi, Nitta, Hiroyuki, Kawabe, Kazuyoshi, Hirakata, Junichi
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): LESPERANCE, JEAN E
• Application Number:
  US09/888,641
• Publication Number:
  US 20020057238A1
• Time in Patent Office: 1,918 Days
• Field of Search: 345/87, 345/88, 345/89, 345/102, 345/98, 345/100, 345/99, 345/94, 345/95, 345/96, 345/97, 345/84, 349/61, 349/68, 349/69, 349/70
• US Class Current: 345/102
• CPC Class Codes: G02F 1/133604 with lamps
• CPC Class Codes: G02F 1/133612 Electrical details
• 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 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• CPC Class Codes: G09G 2320/0257 Reduction of after-image effects
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• CPC Class Codes: G09G 2320/062 Adjustment of illumination source parameters
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/0673 for control of gamma adjustment, e.g. selecting another gamma curve
• 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 2340/16 Determination of a pixel data signal depending on the signal applied in the previous frame
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/2018 by time modulation using two or more time intervals
• CPC Class Codes: G09G 3/2077 by a combination of two or more gradation control methods
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

The present invention includes a panel on which a plurality of pixels are located, a light-source for visualizing an image displayed on the plurality of pixels, a controlling circuit for controlling the light-source, and an image-signal tone characteristic controlling circuit. Moreover, the light-source controlling circuit has a function of repeating a period. Here, the period includes a 1st time-period during which an electric current having a 1st intensity is fed to the light-source, and a 2nd time-period during which an electric current having a 2nd intensity differing from the 1st intensity is fed to the light-source. The light-source controlling circuit controls the 1st time-period and the 2nd time-period in accordance with display information. Also, in accordance with the display information as well, the tone characteristic controlling circuit is controlled so that the excellent contrast will be always available.

Claims

1. A display apparatus for executing a display corresponding to display data to be inputted from the outside, comprising:

a display panel,

a light-source for illuminating said display panel, and

a controlling circuit for controlling light-emission luminance of said light-source irrespective of red, green and blue data of said display data, said controlling circuit switching said light-source between a 1st light-emission luminance and 2nd light-emission luminance during one period for updating said display data to said display, and said controlling circuit changing a time ratio of said 1st light-emission luminance and that of said 2nd light-emission luminance during said one period in accordance with said display data,

wherein said controlling circuit comprises;

a data storing unit for storing said display data by the amount of at least 1 frame,

a data comparing unit for comparing corresponding pixels between said display data stored in said data storing unit and said display data to be inputted, and

a pulse controlling unit for outputting a signal in correspondence with a comparison result by said data comparing unit, said signal controlling said time ratio of said 1st light-emission luminance in said one period.

2. The display apparatus as claimed in claim 1, wherein said data storing unit employs, as a comparison pixel, a portion of all the pixels on said display panel so as to store said display data into said comparison pixel, said data comparing unit comparing said pixel data stored into said comparison pixel with said pixel data of said inputted data corresponding thereto.

3. The display apparatus as claimed in claim 2, wherein said comparison pixel is located at a predetermined position in a display unit of said display panel.

4. A display apparatus for executing a display in correspondence with display data to be inputted, comprising:

a display panel,

a light-source for illuminating said liquid crystal panel,

a luminance distribution detection controlling circuit for detecting, in accordance with said image data to be inputted, luminance distribution data by the amount of at least 1 frame of said image data, and

a tone controlling circuit for updating a set value in at least 1 specified tone position in accordance with said luminance distribution data, and for determining a tone characteristic between said updated respective set values on a 1-frame basis with the use of a predetermined arithmetic-calculation formula.

5. The display apparatus as claimed in claim 4, wherein the number of said specified tones and a spacing between said set tones, which are updated on the 1-frame basis with respect to a tone region, are settable values.

6. The display apparatus as claimed in claim 4, wherein the display apparatus is a liquid crystal display apparatus, and said display panel is a liquid crystal display panel.

7. The display apparatus for executing a display in correspondence with image data to be inputted, comprising:

a display panel,

a light-source for illuminating said display panel,

a luminance distribution detection controlling circuit for detecting, in accordance with said image data to be inputted, luminance distribution data by the amount of at least 1 frame of said image data, and

a light-source controlling circuit for controlling at least either of a light-emission time-period and a light-emission time of said light-source in accordance with said luminance distribution data;

wherein said light-source controlling circuit controls said light-source light-emission time so that a light-source light-emission time for displaying image data becomes longer than a light-source light-emission time for displaying relatively darker image data, said image data being relatively brighter than predetermined image data.

8. The display apparatus as claimed in claim 7, wherein the display apparatus is a liquid crystal display apparatus, and said display panel is a liquid crystal display panel.