Pixel Driving Circuit for Stable Current and Emission Timing
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Solution Overview
Problem
Conventional display devices experience significant variations in current magnitude and light-emitting time due to their current circuit architecture, necessitating a new design to stabilize these parameters.
Innovation Solution
The electronic device incorporates specific transistor and capacitor configurations, along with a current driving element, to control current magnitude and light-emitting time through precise signal management using enabling and sweep signals, ensuring consistent operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional current circuit architecture is used for pixel control, then device complexity is reduced, but current magnitude and light-emitting time vary significantly
Solution Approach 1:
The pixel circuit is segmented into multiple functional blocks: a driving circuit portion with first and second transistors for current control, a control circuit portion with third and fourth transistors for timing control, and storage capacitors. This segmentation allows independent optimization of current stability and timing precision, resolving the contradiction between reliability and complexity.
Solution Approach 2:
The circuit performs preliminary actions by pre-charging capacitors and pre-positioning transistors in specific states before the light-emitting phase. The fourth transistor writes data to the third transistor's control terminal in advance, and the first capacitor stores voltage for the first transistor, ensuring stable current magnitude without requiring complex real-time regulation.
2Manufacturing precision
If conventional time-sharing data writing is used, then ease of operation is improved, but light-emitting time control precision deteriorates
Solution Approach 1:
The circuit employs periodic scanning signals with distinct phases: a first pulse for writing data to the third transistor's control terminal, a second pulse for writing data to the first transistor's control terminal, and a light-emitting phase. This periodic action structure enables precise light-emitting time control while maintaining simple time-sharing data writing operations.
Solution Approach 2:
The third transistor acts as an intermediary between the scanning signal and the light-emitting control. It receives data from the fourth transistor during the scanning phase and transfers it to control the light-emitting duration, decoupling the data writing operation from the light-emitting time control and thereby improving precision without complicating operation.
3Measurement precision
If simple transistor configuration is used, then device complexity is reduced, but current control precision deteriorates
Solution Approach 1:
Different transistors are assigned specialized functions with optimized characteristics: the first and second transistors form a current mirror for precise current replication, while the third and fourth transistors handle digital control signals. This local quality differentiation achieves high current control precision with a relatively simple overall configuration.
Solution Approach 2:
The circuit controls current precision by changing the voltage parameter at the control terminals of transistors. The first capacitor maintains a stable voltage at the first transistor's control terminal, while the second capacitor (with different resistance values for pull-up and pull-down elements) controls the timing of the third transistor. These parameter changes enable precise current and time control without increasing structural complexity.
Data Source
AI summary
An electronic device is provided. The second transistor, the third transistor, the first capacitor and the current driving element are coupled to the first transistor. The fourth transistor writes first and second data to a control terminal of the third transistor and a control terminal of the first transistor according to first and second pulses of a first scanning signal. The second capacitor is coupled to the third transistor and a sweep signal. In a light-emitting period, the second transistor transmits a voltage signal to a first terminal of the first transistor according to an enabling signal and causes the current driving element to emit light. After the third transistor is turned on according to the sweep signal, the voltage signal is transmitted to the control terminal of the first transistor to turn off the first transistor and cause the current driving element to stop emitting light.