Backlight Driver PWM PAM Control for Color Uniformity
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Solution Overview
Problem
As the number of light emitting devices in a backlight unit increases, the resource required for individual driving also increases, and the time for driving one light emitting device is shortened, making it difficult to secure sufficient time for pulse width modulation (PWM) control, which can lead to color distortion and integrity issues in display devices.
Innovation Solution
An electronic apparatus that includes a memory, a backlight unit, a driver, and a processor. The processor identifies specific time intervals for applying currents based on the bits representing the gray level value of an image, allowing for efficient PWM control and minimizing changes in wavelength. The processor controls the driver to adjust the current magnitude in different time intervals, ensuring color uniformity even with an increased number of light emitting devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of light emitting devices in the backlight unit is increased, then the image quality and color accuracy are improved, but the time for driving one light emitting device is shortened and resource requirements increase
Solution Approach 1:
The patent divides the 10-bit gray level value into two separate control mechanisms: PWM control using upper bits (for time interval selection) and PAM control using lower bits (for current magnitude adjustment). This segmentation allows the system to handle high-bit precision requirements without proportionally increasing the number of time intervals, thus maintaining sufficient driving time for each light emitting device while achieving accurate color representation.
2Measurement precision
If the number of light emitting devices is increased, then the image quality is improved, but the resource required for individual driving increases
Solution Approach 1:
The patent combines PWM and PAM control methods into a unified driving scheme. By merging the time-based control (PWM) with amplitude-based control (PAM), the system achieves 10-bit precision control without requiring proportionally more driving resources. The lower bits control current magnitude directly, reducing the need for extensive time-multiplexed control resources that would be required with PWM alone.
Solution Approach 2:
The patent dynamically adjusts the current magnitude based on the lower bits of the gray level value, allowing flexible control of light emission intensity. This dynamic amplitude adjustment complements the time-based PWM control, enabling precise control of light emitting devices without requiring fixed, resource-intensive timing schemes for each device.
3Ease of operation
If pulse amplitude modulation (PAM) control is used to change current magnitude, then the gray level control is simplified, but the wavelength changes causing color distortion
Solution Approach 1:
The patent applies different control strategies to different parts of the gray level value: upper bits control the time interval (affecting overall brightness) while lower bits control the current magnitude (affecting fine brightness adjustment). By localizing the PAM control to only the lower bits and combining it with PWM control for the upper bits, the system maintains color accuracy while simplifying control operations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution efficiently drives the backlight unit while maintaining color uniformity, reducing the risk of color distortion and integrity issues in display devices, even as the number of light emitting devices increases.
Implementation Method 1
the light emitting device is implemented as a light emitting diode (LED), and wavelength of the LED varies according to currents
Data Source
AI summary
An electronic apparatus is provided, which includes a memory storing an input image, a backlight unit, a driver configured to output a driving current to the backlight unit, and a processor configured to identify a time interval at which current is applied among a plurality of time intervals based on a value of a plurality of first bits among a plurality of bits representing a gray level value of the input image, and control the driver to change a magnitude of a current of a time interval among the plurality of time intervals based on at least one second bit which is the rest of the plurality of bits excluding the plurality of first bits, and a number of the plurality of time intervals is determined based on the number of the plurality of first bits.