Display Driver Bias Timing for Low-Frequency Luminance Uniformity
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Solution Overview
Problem
In display devices, luminance deviations occur between pixel areas due to increased leakage current in low frequency driving, which is compensated by applying a bias voltage, resulting in timing differences in applying the bias voltage to each pixel row.
Innovation Solution
A driver system that controls the timing and level of bias voltages applied to pixel areas, with a delay of one emission cycle between successive bias voltages, and step-wise changes in voltage levels during the blank period to maintain consistent luminance across pixel areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bias voltage is applied to pixels in response to gate signals to compensate the leakage current of the pixels, then the leakage current compensation is improved, but the luminance deviation between pixel areas increases due to timing differences
Solution Approach 1:
The patent applies bias voltages to different pixel rows in advance during the blank period before the active period, ensuring that each pixel receives the appropriate bias voltage timing. By pre-applied the bias voltage to pixel rows in a controlled sequence during the blank period, the system compensates for leakage current without causing luminance deviation during the actual display period.
Solution Approach 2:
The patent uses periodic blank periods between frame periods to apply bias voltages to different pixel rows sequentially. During each blank period, bias voltages are applied to successive pixel rows in a controlled manner, creating a periodic action that ensures uniform luminance across all pixel areas while maintaining effective leakage current compensation.
2Use of energy by moving object
If the driving frequency is reduced to save energy or reduce refresh rate, then the power consumption is reduced, but the leakage current increases causing luminance deviation
Solution Approach 1:
The patent applies bias voltages to pixel rows in advance during the blank period before the active period. By pre-applied the bias voltage to compensate for leakage current that will occur during the longer frame period at low frequency, the system maintains luminance uniformity while operating at reduced driving frequencies.
Solution Approach 2:
The patent dynamically adjusts the timing and sequence of bias voltage application based on the driving frequency. At lower frequencies with longer frame periods, the system extends the blank period and adjusts the sequential bias voltage application timing accordingly, ensuring that leakage current compensation remains effective while maintaining power savings.
Data Source
AI summary
A display device includes a display panel which includes first to nth pixel areas arranged in a direction, where n is a natural number greater than or equal to 2, an emission control driver which provides an emission control signal having a plurality of emission cycles corresponding to a number of outputs of a gate-on voltage during a frame period to the first to nth pixel areas, a power supply which generates first to nth bias voltages respectively provided to the first to nth pixel areas, and a timing controller which controls timings when the first to nth bias voltages are supplied to the first to nth pixel areas in a way such that a kth bias voltage is provided with a delay of one emission cycle from a (k−1)th bias voltage, where k is a natural number greater than or equal 2 and less than or equal n.