Image display apparatus and method for controlling same

• US 10,636,368 B2
• Filed: 02/12/2016
• Issued: 04/28/2020
• Est. Priority Date: 02/23/2015
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kimura, Takushi, Kanai, Izumi, Furumoto, Yoshihisa, Ikeda, Takeshi
• Primary Examiner(s): Tzeng, Fred
• Application Number:
  US15/547,579
• Publication Number:
  US 20180040279A1
• Time in Patent Office: 1,537 Days
• Field of Search: 345102
• CPC Class Codes: G02F 1/133602 Direct backlight
• CPC Class Codes: G02F 1/133611 including means for improving the brightness uniformity
• CPC Class Codes: G02F 2203/64 Normally black display, i.e. the off state being black
• CPC Class Codes: G09G 2320/0238 Improving the black level
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• 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 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers

Abstract

An image display apparatus includes: a display unit; a plurality of light emitting units; and a light-emission controller configured to individually control light-emission brightness of each of the light emitting units, wherein in a case where brightness of light applied to a region of the display unit on which a black region of an input image is displayed is less than or equal to predetermined brightness, transmittance of the display unit is controlled such that transmittance of the region of the display unit corresponding to the black region becomes higher than that in a case in which the brightness is higher than the predetermined brightness.

Claims

1. An image display apparatus comprising:

a display panel configured to display an image by transmitting light;

a plurality of light sources configured to apply light to the display panel;

at least one processor and/or at least one circuit that performs operations of the following units;

a first correction unit configured to generate a first image by increasing a gradation value of an input image that is smaller than a first gradation value;

a light-emission control unit configured to individually control light-emission brightness of each of the light sources based on brightness of each part of the first image corresponding to each of the light sources;

a second correction unit configured to generate a second image by correcting a gradation value of a pixel of the first image according to brightness of light applied to a region of the display panel corresponding to the pixel; and

a third correction unit configured to generate a third image by reducing a gradation value of the second image that is smaller than a second gradation value, wherein

transmittance of the display panel is controlled based on the third image.

2. The image display apparatus according to claim 1, wherein

the third correction unit converts the gradation value of the second image that is smaller than the second gradation value, into a gradation value representing a black color.

3. The image display apparatus according to claim 1, wherein

the at least one processor and/or the at least one circuit further performs operations of the following units:

an estimation unit configured to estimate distribution of the brightness of the light applied to the display panel using the light-emission brightness of each of the light sources, and

the second correction unit corrects a gradation value of a pixel of the first image based on the brightness estimated by the estimation unit for a region of the display panel corresponding to the pixel.

4. The image display apparatus according to claim 1, wherein

the at least one processor and/or the at least one circuit further performs operations of the following units:

a brightness setting unit configured to set a maximum value of display brightness capable of being displayed by the image display apparatus, and

a ratio of a minimum value of light-emission brightness capable of being controlled by the light-emission control unit to a maximum value of the light-emission brightness capable of being controlled by the light-emission control unit is smaller as the maximum value of the display brightness is higher.

5. The image display apparatus according to claim 1, wherein

a ratio of a minimum value of light-emission brightness capable of being controlled by the light-emission control unit controller to a maximum value of the light-emission brightness capable of being controlled by the light-emission control unit is smaller as the first gradation value is greater.

6. The image display apparatus according to claim 1, wherein

the first correction unit generates the first image such that a gradation value of the first image is greater than or equal to a value corresponding to a target contrast set by a user input.

7. A method for controlling an image display apparatus having

a display panel configured to display an image by transmitting light, and

a plurality of light sources configured to apply light to the display panel,

the method comprising:

a first correction step of generating a first image by increasing a gradation value of an input image that is smaller than a first gradation value;

a light-emission control step of individually controlling light-emission brightness of each of the light sources based on brightness of each part of the first image corresponding to each of the light sources;

a second correction step of generating a second image by correcting a gradation value of a pixel of the first image according to brightness of light applied to a region of the display panel corresponding to the pixel; and

a third correction step of generating a third image by reducing a gradation value of the second image that is smaller than a second gradation value; and

a control step of controlling light transmittance of the display panel based on the third image.

8. The method according to claim 7, wherein

in the third correction step, the gradation value of the second image that is smaller than the second gradation value is converted into a gradation value representing a black color.

9. The method according to claim 7, further comprising:

an estimation step of estimating distribution of the brightness of the light applied to the display panel using the light-emission brightness of each of the light sources, wherein

in the second correction step, a gradation value of a pixel of the first image is corrected based on the brightness estimated in the estimation step for a region of the display panel corresponding to the pixel.

10. The method according to claim 7, further comprising:

a brightness setting step of setting a maximum value of display brightness capable of being displayed by the image display apparatus, wherein

a ratio of a minimum value of light-emission brightness capable of being controlled in the light-emission control step to a maximum value of the light-emission brightness capable of being controlled in the light-emission control step is smaller as the maximum value of the display brightness is higher.

11. The method according to claim 7, wherein

a ratio of a minimum value of light-emission brightness capable of being controlled in the light-emission control step to a maximum value of the light-emission brightness capable of being controlled in the light-emission control step is smaller as the first gradation value is greater.