LED Current Supply Circuit With Dynamic Mirror Ratio by Greyscale
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Solution Overview
Problem
Existing display devices face challenges in properly adjusting LED voltage or current based on greyscale values, leading to inadequate image resolution and unnecessary power consumption, especially in low greyscale areas.
Innovation Solution
A current supply circuit that includes a voltage/current converter and a current mirror circuit to convert data voltage into data current, with a compensation current generation circuit to adjust the current mirror ratio and supply additional current in high greyscale sections, improving resolution and power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a constant LED current is supplied regardless of greyscale value, then power consumption is reduced, but image resolution deteriorates in low greyscale areas
Solution Approach 1:
The patent changes the current mirror ratio parameter dynamically based on greyscale value. In low greyscale areas, a first current mirror ratio is used to maintain high resolution, while in high greyscale areas, a second current mirror ratio (with larger current change rate) is applied. This parameter adaptation resolves the contradiction by optimizing both resolution and power consumption across different operating conditions.
Solution Approach 2:
The invention introduces dynamic adjustment of the current mirror ratio through a compensation current generation circuit that responds to the data voltage level. The circuit automatically switches between different current mirror ratios based on whether the greyscale value is low or high, making the system adaptive rather than static. This dynamic behavior enables the system to achieve low power consumption in high greyscale areas while maintaining high resolution in low greyscale areas.
2Illumination intensity
If a data current with high change rate is supplied, then brightness adjustment range is improved, but image resolution deteriorates in low greyscale areas
Solution Approach 1:
The patent applies different current mirror ratios for different greyscale ranges. For low greyscale values, a first current mirror ratio with smaller current change rate is used to maintain high resolution and prevent unnecessary brightness changes. For high greyscale values, a second current mirror ratio with larger current change rate is used to expand the brightness adjustment range. This local optimization resolves the contradiction by tailoring the current change rate to the specific greyscale region.
3Power
If current mirror ratio is increased, then LED current control range is improved, but power consumption increases
Solution Approach 1:
The invention makes the current mirror ratio dynamic by introducing a compensation current generation circuit that adjusts the ratio based on the data voltage level. When the greyscale value is high, the circuit switches to a second current mirror ratio that provides larger LED current control range. When the greyscale value is low, it uses a first current mirror ratio that consumes less power. This dynamic switching resolves the contradiction between control range and power consumption.
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
This solution allows for precise control of LED brightness across greyscale sections, enhancing image resolution and reducing power consumption, while maintaining compatibility with existing display devices.
Implementation Method 1
a voltage/current converter configured to convert a data voltage, received from a data driving circuit, into a data current
Implementation Method 2
a first current mirror circuit configured to mirror the data current so that a light-emitting diode (LED) current flows into an LED array
Implementation Method 3
a light-emitting diode (LED) configured to emit light in accordance with a level or change rate of the data current
Data Source
AI summary
A current supply circuit according to the present disclosure may include a voltage/current converter configured to convert, into a data current, a data voltage received from a data driving circuit and a first current mirror circuit configured to mirror the data current so that a light-emitting diode (LED) current flows into an LED array. The data current may be adjusted based on a greyscale value of the LED array.