Pixel Circuit Transistor Count Reduction for Aperture Ratio
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Solution Overview
Problem
High-definition and enlarged electro-optical devices require accurate control of electro-optical elements, but existing pixel circuits with multiple transistors lead to yield deterioration and aperture ratio issues due to increased transistor count.
Innovation Solution
The electronic circuit design includes a unit circuit with fewer transistors, utilizing a first transistor connected to a power source line, a second transistor for controlling the drain-gate connection, and a third transistor for controlling the connection to a current source, allowing for reduced transistor count while maintaining accurate electrical connection states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel circuits include four or more transistors to compensate for characteristic deviation, then compensation accuracy is improved, but yield deteriorates and aperture ratio decreases
Solution Approach 1:
The patent changes the operational parameters and timing of transistor switching to enable accurate characteristic compensation with fewer transistors. By controlling the on/off states of transistors at specific timing and utilizing voltage holding capabilities, the circuit achieves compensation accuracy previously requiring more transistors, thereby improving yield without sacrificing precision.
2Measurement precision
If pixel circuits include four or more transistors to compensate for characteristic deviation, then compensation accuracy is improved, but aperture ratio decreases
Solution Approach 1:
The patent merges multiple functions into fewer transistors by utilizing the same transistors for both compensation and driving operations at different timing. The first and second transistors serve dual purposes: compensating for characteristic deviations during compensation periods and driving electro-optical elements during display periods, eliminating the need for separate dedicated compensation transistors and thus improving aperture ratio.
Solution Approach 2:
The patent implements dynamic switching of transistor connections and operational modes. Transistors are switched between different circuit configurations and functional states (on/off) at specific timing to perform compensation, holding, and driving operations sequentially. This dynamic operation allows fewer transistors to accomplish what previously required a larger static circuit, thereby increasing aperture ratio.
3Reliability
If the number of transistors is reduced in pixel circuits, then yield and aperture ratio are improved, but control precision over electro-optical elements may deteriorate
Solution Approach 1:
The patent performs compensation operations preliminarily before the actual driving operation. The first transistor compensates for characteristic deviations and the second transistor holds the compensated voltage in advance, preparing the circuit for accurate subsequent driving. This preliminary compensation ensures that even with fewer transistors, the control precision is maintained by pre-correcting any deviations.
Solution Approach 2:
The patent implements a feedback mechanism where the state of electro-optical elements and transistor characteristics are compensated based on detected deviations. The compensation circuit uses feedback from the actual operating conditions to adjust and correct characteristic variations, ensuring precise control is maintained despite the reduced transistor count.
Data Source
AI summary
The present invention provides an electronic circuit, a method of driving the electronic circuit, an electro-optical device, a method of driving the electro-optical device, and an electronic apparatus capable of improving yield or aperture ratio by reducing the number of transistors to be used. A pixel circuit can include a driving transistor, a transistor, a switching transistor, and a holding capacitor. Furthermore, a driving-voltage supplying transistor is connected between a first power source line, which supplies a driving voltage to drive the driving transistor, and a voltage supply line extending in a row in the direction of the pixel circuits provided at the right end side of an active matrix part.