Backlight control signal duty cycle extension scheme to avoid flicker
AssigneeQUALCOMM Incorporated
InventorsLiangguo Shen, Joseph Dale Rutkowski, Sugato Mukherjee
Life of this patent
Estimating the term…
Abstract
Certain aspects are directed to a circuit for brightness control. The circuit generally includes: a duty cycle adjustment circuit configured to receive a first backlight control signal having a first duty cycle and generate a second backlight control signal having a second duty cycle, the second duty cycle being greater than the first duty cycle if the first duty cycle is less than a threshold; a digital processor configured to set a value of a software brightness code based on the second duty cycle; and a backlight control circuit configured to drive a backlight in accordance with the software brightness code and the second duty cycle of the second backlight control signal.
Claims23
A circuit for brightness control, comprising:
- a duty cycle adjustment circuit configured to:
- receive a first backlight control signal having a first duty cycle;
- and
- generate a second backlight control signal having a second duty cycle by applying a duty cycle adjustment factor to the first backlight control signal, the second duty cycle being greater than the first duty cycle if the first duty cycle is less than a threshold;
- a digital processor configured to set a value of a software brightness code by dividing an input software brightness code by a code adjustment factor, a value of the code adjustment factor being equal to a value of the duty cycle adjustment factor;
- and
- a backlight control circuit configured to drive a backlight in accordance with the software brightness code and the second duty cycle of the second backlight control signal.
(canceled)
A method for brightness control, comprising:
- receiving, at a duty cycle adjustment circuit, a first backlight control signal having a first duty cycle;
- generating, via the duty cycle adjustment circuit, a second backlight control signal having a second duty cycle by applying a duty cycle adjustment factor to the first backlight control signal, the second duty cycle being greater than the first duty cycle if the first duty cycle is less than a threshold;
- setting, via a digital processor, a value of a software brightness code by dividing an input software brightness code by a code adjustment factor, a value of the code adjustment factor being equal to a value of the duty cycle adjustment factor;
- and
- driving, via a backlight control circuit, a backlight in accordance with the software brightness code and the second duty cycle of the second backlight control signal.
(canceled)
(canceled)
A circuit for brightness control, comprising:
- a duty cycle adjustment circuit comprising:
- a first current source;
- a first capacitive element;
- a first switch configured to selectively couple the first current source to the first capacitive element based on a first backlight control signal;
- a second current source;
- a second capacitive element;
- and
- a second switch configured to couple the second current source to the second capacitive element in response to a rising edge of the first backlight control signal, wherein the duty cycle adjustment circuit is configured to:
- receive the first backlight control signal having a first duty cycle;
- and
- generate a second backlight control signal having a second duty cycle, the second duty cycle being greater than the first duty cycle if the first duty cycle is less than a threshold;
- a digital processor configured to set a value of a software brightness code based on the second duty cycle;
- and
- a backlight control circuit configured to drive a backlight in accordance with the software brightness code and the second duty cycle of the second backlight control signal.
Dependencies are inferred from the claim text.