BACKLIGHT APPARATUS, METHOD FOR CONTROLLING THE SAME, AND IMAGE DISPLAY APPARATUS

• US 20130016306A1
• Filed: 07/05/2012
• Published: 01/17/2013
• Est. Priority Date: 07/15/2011
• Status: Abandoned Application

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Ohno, Tomoyuki, Takayanagi, Daisuke
• Application Number:
  US13/542,107
• Publication Number:
  US 20130016306A1
• Time in Patent Office: Days
• US Class Current: 349/61
• CPC Class Codes: G02B 6/0078 Side-by-side arrangements, e.g. for large area displays
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix

Abstract

Disclosed is a backlight apparatus of an image display apparatus capable of changing an position of a screen; the backlight apparatus comprising a plurality of light sources which are provided for a plurality of light source blocks and for which light emission can be controlled independently in relation to each of the light source blocks; a storage unit which stores data to be used in order to determine a driving signal for the light source, the data being determined so that a luminance of each of the light source blocks is included within a predetermined allowable range with respect to a target luminance in relation to each of the positions of the screen; an acquiring unit which acquires the position of the screen; and a control unit which determines the driving signal for the light source by using the data corresponding to the position of the screen.

Claims

1. A backlight apparatus of an image display apparatus capable of changing an position of a screen, the backlight apparatus comprising:

a plurality of light sources which are provided for a plurality of light source blocks and for which light emission can be controlled independently in relation to each of the light source blocks;

a storage unit which stores unevenness correction data as data to be used in order to determine a driving signal for the light source of each of the light source blocks, the unevenness correction data being determined so that a luminance of each of the light source blocks is included within a predetermined allowable range with respect to a target luminance in relation to each of a plurality of predetermined positions of the screen;

an acquiring unit which acquires the position of the screen; and

a control unit which determines the driving signal for the light source of each of the light source blocks by using the unevenness correction data corresponding to the position of the screen.

2. The backlight apparatus according to claim 1, wherein:

the unevenness correction data is data which is determined for each of the plurality of predetermined positions of the screen and each of the target luminances of the backlight apparatus;

the acquiring unit further acquires the target luminance of the backlight apparatus; and

the control unit determines the driving signal for the light source of each of the light source blocks by using the unevenness correction data corresponding to the position of the screen and the target luminance of the backlight apparatus.

3. The backlight apparatus according to claim 2, further comprising:

a setting unit which sets the target luminance for each of the light source blocks in conformity with an image disposed in a display area corresponding to each of the light source blocks, wherein;

the control unit determines the driving signal for the light source of each of the light source blocks by using the unevenness correction data corresponding to the position of the screen and the target luminance of the light source block in relation to each of the light source blocks.

4. The backlight apparatus according to claim 1, further comprising:

a detecting unit which detects any change of the position of the screen, wherein;

the unevenness correction data, which is used to determine the driving signal for the light source of each of the light source blocks, is changed by the control unit to the unevenness correction data corresponding to the position of the screen to be provided after being changed, if any change of the position of the screen is detected.

5. The backlight apparatus according to claim 4, wherein the unevenness correction data, which is used to determine the driving signal for the light source of each of the light source blocks, is changed by the control unit to the unevenness correction data corresponding to the position of the screen to be provided after being changed, after a predetermined period of time elapses after any change of the position of the screen is detected.

6. The backlight apparatus according to claim 5, wherein the control unit determines the predetermined period of time depending on a screen size of the image display apparatus and the target luminance of the backlight apparatus.

7. The backlight apparatus according to claim 4, further comprising:

a temperature difference detecting unit which detects a temperature difference between the two light source blocks; and

a judging unit which judges whether or not a detected value of the temperature difference between the two light source blocks is coincident with a predetermined reference value, wherein;

the unevenness correction data, which is used to determine the driving signal for the light source of each of the light source blocks, is changed by the control unit to the unevenness correction data corresponding to the position of the screen to be provided after being changed, after a number of combinations, each of which is included in a plurality of predetermined combinations of the two light source blocks and each of which is judged by the judging unit to have the detected value of the temperature difference coincident with the reference value, are provided so that the number is not less than a predetermined number, after any change of the position of the screen is detected.

8. The backlight apparatus according to claim 1, wherein the image display apparatus is capable of changing at least any one of a rotational position about an axis which is perpendicular to the screen and a tilt angle about an axis which is parallel to the screen and which is perpendicular to a vertical direction, as the position of the screen.

9. The backlight apparatus according to claim 1, wherein:

each of the light source blocks has the light sources of a plurality of colors; and

the unevenness correction data is data which is determined for each of the colors of the light sources, each of the plurality of predetermined positions of the screen, and each of the target luminances of the respective colors of the backlight apparatus.

10. An image display apparatus comprising:

the backlight apparatus as defined in claim 1; and

a liquid crystal panel which is illuminated by the backlight apparatus.

11. A method for controlling a backlight apparatus of an image display apparatus capable of changing an position of a screen, the backlight apparatus comprising a plurality of light sources which are provided for a plurality of light source blocks and for which light emission can be controlled independently in relation to each of the light source blocks, the method comprising:

a reading step of reading unevenness correction data as data to be used in order to determine a driving signal for the light source of each of the light source blocks, the unevenness correction data being determined so that a luminance of each of the light source blocks is included within a predetermined allowable range with respect to a target luminance in relation to each of a plurality of predetermined positions of the screen;

an acquiring step of acquiring the position of the screen; and

a control step of determining the driving signal for the light source of each of the light source blocks by using the unevenness correction data corresponding to the position of the screen.

12. The method for controlling the backlight apparatus according to claim 11, wherein:

the unevenness correction data is data which is determined for each of the plurality of predetermined positions of the screen and each of the target luminances of the backlight apparatus;

the target luminance of the backlight apparatus is further acquired in the acquiring step; and

the driving signal for the light source of each of the light source blocks is determined in the control step by using the unevenness correction data corresponding to the position of the screen and the target luminance of the backlight apparatus.

13. The method for controlling the backlight apparatus according to claim 12, further comprising:

a setting step of setting the target luminance for each of the light source blocks in conformity with an image disposed in a display area corresponding to each of the light source blocks, wherein;

the driving signal for the light source of each of the light source blocks is determined in the control step by using the unevenness correction data corresponding to the position of the screen and the target luminance of the light source block in relation to each of the light source blocks.

14. The method for controlling the backlight apparatus according to claim 11, further comprising:

a detecting step of detecting any change of the position of the screen, wherein;

the unevenness correction data, which is used to determine the driving signal for the light source of each of the light source blocks, is changed in the control step to the unevenness correction data corresponding to the position of the screen to be provided after being changed, if any change of the position of the screen is detected.

15. The method for controlling the backlight apparatus according to claim 14, wherein the unevenness correction data, which is used to determine the driving signal for the light source of each of the light source blocks, is changed in the control step to the unevenness correction data corresponding to the position of the screen to be provided after being changed, after a predetermined period of time elapses after any change of the position of the screen is detected.

16. The method for controlling the backlight apparatus according to claim 15, wherein the predetermined period of time is determined in the control step depending on a screen size of the image display apparatus and the target luminance of the backlight apparatus.

17. The method for controlling the backlight apparatus according to claim 14, further comprising:

a temperature difference detecting step of detecting a temperature difference between the two light source blocks; and

a judging step of judging whether or not a detected value of the temperature difference between the two light source blocks is coincident with a predetermined reference value, wherein;

the unevenness correction data, which is used to determine the driving signal for the light source of each of the light source blocks, is changed in the control step to the unevenness correction data corresponding to the position of the screen to be provided after being changed, after a number of combinations, each of which is included in a plurality of predetermined combinations of the two light source blocks and each of which is judged in the judging step to have the detected value of the temperature difference coincident with the reference value, are provided so that the number is not less than a predetermined number, after any change of the position of the screen is detected.