TRANSMISSIVE DISPLAY DEVICE

• US 20080111784A1
• Filed: 11/07/2007
• Published: 05/15/2008
• Est. Priority Date: 11/13/2006
• 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: TANAKA, Hiroshi, Morisue, Takashi, Yumoto, Manabu, Muramatsu, Tsuyoshi, Aoki, Atsushi
• Granted Patent: US 7,944,431 B2
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• 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 3/3611 Control of matrices with row and column drivers

Abstract

Each of image data sorted so as to correspond to divided areas respectively is stored in an in-area image memory. A maximum luminance extracting section extracts the maximum luminance value therefrom and records it onto the maximum luminance storage section. In accordance with the maximum luminance value that is thus stored in the maximum luminance storage section and that each of the areas has, a BL candidate value calculating section and a BL luminance difference adjusting section determine an emitted-light luminance in a target area such that a difference between the backlight luminance in the target area and the backlight luminance in its adjacent area is not more than a tolerance value.

Claims

1. A transmissive display device, comprising:

a backlight, including a plurality of light emitting areas capable of controlling emitted-light luminances respectively;

a transmission control panel for controlling transmittances for the light emitted from the backlight for display;

emitted-light luminance setting means for setting emitted-light luminances in the light emitting areas of the backlight respectively; and

transmittance setting means for setting the transmittances in pixels of the transmission control panel in accordance with the emitted-light luminances in the light emitting areas of the backlight respectively,

the emitted-light luminance setting means setting the emitted-light luminances such that either a difference between emitted-light luminances in adjacent emitting areas of the backlight or a ratio of the emitted-light luminances in the adjacent light emitting areas is not more than a tolerance value.

2. The transmissive display device as set forth in claim 1, wherein:

the emitted-light luminance setting means includes;

initial emitted-light luminance setting means for setting each of the emitted-light luminances of the light emitting areas of the backlight at an emitted-light luminance minimally required for display on a pixel with a maximum luminance in the light emitting area; and

emitted-light luminance correcting means for correcting the emitted-light luminances, set by the initial emitted-light luminance setting means, of the light emitting areas such that either the difference between the emitted-light luminances in the adjacent emitting areas or the ratio of the emitted-light luminances in the adjacent light emitting areas is not more than the tolerance value.

3. The transmissive display device as set forth in claim 2, wherein:

among the emitted-light luminances set by the initial emitted-light luminance setting means, the emitted-light luminance correcting means extracts a light emitting area having an emitted-light luminance whose difference from an emitted-light luminance of an adjacent light emitting area or whose ratio to the emitted-light luminance of the adjacent light emitting area is not less than the tolerance value, and increases the emitted-light luminance of the light emitting area thus extracted, so as to correct the difference between the emitted-light luminances of the adjacent light emitting areas or the ratio of the emitted-light luminances such that the difference or the ratio is not more than the tolerance value.

4. The transmissive display device as set forth in claim 3, wherein:

to correct the emitted-light luminances, the emitted-light luminance correcting means repeats a correction process of (1) comparing an emitted-light luminance of a target area for correction with either (i) a value obtained by subtracting the tolerance value from an emitted-light luminance of at least one comparative area adjacent to the target area, or (ii) a value obtained by multiplying the tolerance value by the emitted-light luminance of said at least one comparative area, and (2) adopting a maximum value of the compared values as a corrected emitted-light luminance of the target area,

the correction process includes a first process of sequentially shifting the target area from left to right in a display screen, a second process of sequentially shifting the target area from right to left in the display screen, a third process of sequentially shifting the target area from upward to downward in the display screen, and a fourth process of sequentially shifting the target area from downward to upward in the display screen, and

during each of the first to fourth processes, the comparative area is a light emitting area having been set as a target area earlier than the target area currently being subjected to the correction process.

5. The transmissive display device as set forth in claim 2, wherein:

the emitted-light luminance correcting means maintains a light emitting area having an emitted-light luminance of 0 before correction such that the light emitting area has an emitted-light luminance of 0 after the correction.

6. A display control method for a transmissive display device including a backlight, including a plurality of light emitting areas capable of controlling emitted-light luminances respectively;

and a transmission control panel for controlling transmittances for the light emitted from the backlight for display,

said display control method, comprising;

an initial emitted-light luminance setting step of setting each of the emitted-light luminances of the light emitting areas of the backlight at an emitted-light luminance minimally required for display on a pixel with a maximum luminance in the light emitting area; and

an emitted-light luminance correcting step of correcting the emitted-light luminances, set in the initial emitted-light luminance setting step, of the light emitting areas such that either a difference between emitted-light luminances in adjacent emitting areas or a ratio of the emitted-light luminances in the adjacent light emitting areas is not more than a tolerance value,

the emitted-light luminance correcting step being performed to correct the emitted-light luminances by repeating a correction process of (1) comparing an emitted-light luminance of a target area for correction with either (i) a value obtained by subtracting the tolerance value from an emitted-light luminance of at least one comparative area adjacent to the target area, or (ii) a value obtained by multiplying the tolerance value by the emitted-light luminance of said at least one comparative area, and (2) adopting a maximum value of the compared values as a corrected emitted-light luminance of the target area,

the correction process including a first process of sequentially shifting the target area from left to right in a display screen, a second process of sequentially shifting the target area from right to left in the display screen, a third process of sequentially shifting the target area from upward to downward in the display screen, and a fourth process of sequentially shifting the target area from downward to upward in the display screen, and

during each of the first to fourth processes, the comparative area being a light emitting area having been set as a target area earlier than the target area currently being subjected to the correction process.

7. A computer-readable storage medium storing a display control program for causing a computer to perform the steps of the display control method as set forth in claim 6 for the transmissive display device.