Display Device Clock Signal Control for Compensation Accuracy
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Solution Overview
Problem
The existing organic EL display devices suffer from decreased compensation accuracy due to coupling noise generated in the data signal line, which affects the accurate measurement of current flowing through the pixel circuits, leading to inadequate correction for drive transistor degradation.
Innovation Solution
The display device incorporates a control circuit that stops the outputs of light-emission control clock signals during the current measurement period, ensuring that light-emission control signals remain at a constant level, thereby preventing coupling noise and allowing for accurate detection of the drive transistor's current characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If real-time monitoring is performed during normal display period, then compensation for drive transistor degradation can be achieved, but coupling noise is generated in data signal line which decreases measurement precision
Solution Approach 1:
The patent applies preliminary action by stopping the light-emission control clock signals before performing current measurement during the monitoring period. This preparatory step ensures that light-emission control signals remain at a constant level, preventing coupling noise from being generated in the data signal line before the measurement process begins, thereby ensuring accurate current measurement for drive transistor degradation compensation.
2Productivity
If light-emission control signals change level during measurement period, then normal display operation can proceed, but coupling noise is generated which affects current measurement accuracy
Solution Approach 1:
The patent applies segmentation by dividing the monitoring period into distinct phases: a light-emission control clock signal stop period followed by a current measurement period. During the stop period, clock signals are halted to maintain constant light-emission control signal levels and eliminate coupling noise. During the measurement period, current measurement is performed with high precision. This temporal segmentation allows both display operation continuity and measurement precision to be maintained.
Data Source
AI summary
In a display device having an external compensation function, a decrease in compensation accuracy caused by coupling noise generated in a data signal line is prevented. An emission driver that applies a light-emission control signal (EM) to each of a plurality of light-emission control lines includes a shift register formed of a plurality of unit circuits. The shift register generates a light-emission control signal (EM) to be applied to each light-emission control line on the basis of a plurality of light-emission control clock signals (ECK1 to ECK4) outputted from a display control circuit. The display control circuit stops the outputs of the plurality of light-emission control clock signals (ECK1 to ECK4) throughout a current measurement period in which a current corresponding to the characteristic of the drive transistor is measured.