Display Power Control Using Step-Wise Voltage Ramping
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Solution Overview
Problem
Display devices face issues with driving current exceeding limit values and power consumption exceeding specifications due to delayed voltage adjustments based on previous frame load and grayscale, leading to potential malfunction and increased manufacturing costs.
Innovation Solution
A display device with a timing controller that adjusts the voltage rising time of the first driving power in response to differential voltage and current values, using a sensing resistor and current sensor to ensure stable operation by controlling the voltage in a step-wise manner based on load and peak grayscale.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the voltage of the first driving power is determined based on the load and peak grayscale of the previous frame, then the voltage adjustment is simple to implement, but the driving current may exceed the limit current value and power consumption may exceed the power specification
Solution Approach 1:
The timing controller determines the voltage of the first driving power in advance based on the load and peak grayscale of the current frame before the frame is displayed, rather than using the previous frame's data. This preliminary determination prevents driving current from exceeding limit values by proactively adjusting voltage based on actual current frame requirements.
Solution Approach 2:
The voltage rising time of the first driving power is dynamically adjusted based on the differential voltage value between the current frame voltage and previous frame voltage, as well as the differential current value. When the differential current value exceeds a threshold, the voltage rises in a step-wave form with extended rising time, otherwise it rises normally, making the system adaptive to current conditions.
2Use of energy by stationary object
If the voltage of the first driving power is rapidly adjusted to match the current frame load, then the power consumption control is improved, but the voltage adjustment speed may cause instability in driving current
Solution Approach 1:
The voltage rising time is dynamically controlled based on the differential current value between the maximum current and global current. When the differential current value exceeds a threshold, the voltage rises in a step-wave form with extended rising time to ensure stability. When it does not exceed the threshold, the voltage rises normally for faster power consumption control.
Solution Approach 2:
The timing controller compares the differential current value with a threshold value and adjusts the voltage rising time accordingly. This feedback mechanism ensures that voltage adjustment speed adapts to current conditions, maintaining driving current stability while controlling power consumption effectively.
3Reliability
If the voltage rising time is extended to prevent current exceeding, then the driving stability is improved, but the response time to load changes is delayed
Solution Approach 1:
The voltage rising time is not fixed but dynamically adjusted based on the differential current value. When the differential current value exceeds a threshold, the voltage rises in a step-wave form with extended rising time to ensure stability. When it does not exceed the threshold, the voltage rises normally for faster response, thus avoiding unnecessary delays.
Solution Approach 2:
The voltage rising time parameter is changed based on the differential current value and differential voltage value. By adjusting this parameter dynamically, the system achieves both driving stability and fast response to load changes, resolving the contradiction between extended rising time and response speed.
Data Source
AI summary
A display device includes a display including pixels connected to a first power line, a second power line, scan lines, and data lines, a current sensor for sensing a global current value flowing to the pixels, a power generator for supplying a first driving power and a second driving power to the first and second power lines, and a timing controller for controlling the power generator so that a voltage rising time of the first driving power is changed in response to a differential voltage value corresponding to a difference between a voltage of the first driving power of a previous frame and a voltage of the first driving power of a current frame, and in response to a differential current value corresponding to a difference between the global current value and a maximum current value to flow to the pixels in response to a load of the display.