Pixel Circuit Body Voltage Compensation for UV-Induced Luminance Shift
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Solution Overview
Problem
The accumulation of charges on the substrate of a display device due to external ultraviolet light causes a negative bias on the transistor body, leading to a shift in the threshold voltage and resulting in luminance deviation and deteriorated image quality.
Innovation Solution
The implementation of a pixel with a body capacitor and a body transistor connected between the second terminal and the body of the transistor, the body of the transistor, the solution is to compensate the technical problem by applying a capacitor and transistor to stabilize the body voltage, thereby reducing luminance deviation and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pixel structure without body voltage compensation is used, then the device complexity is low, but the luminance stability deteriorates due to threshold voltage shifts caused by charge accumulation from ultraviolet light
Solution Approach 1:
The pixel circuit is segmented by adding separate body voltage control components (body capacitor and body transistor) that independently manage the body voltage of the driving transistor. This segmentation allows the body voltage to be controlled separately from other circuit parameters, enabling stable threshold voltage compensation without disrupting the overall pixel structure.
Solution Approach 2:
A body capacitor is introduced as an intermediary element between the body terminal of the driving transistor and the third node. This capacitor acts as a mediator that stores and supplies charge to maintain stable body voltage, thereby compensating for threshold voltage shifts caused by ultraviolet-induced charge accumulation on the substrate.
2Reliability
If charges accumulate on the substrate due to external ultraviolet light, then the body voltage of the transistor shifts, but adding body voltage compensation components increases the number of circuit elements
Solution Approach 1:
The body transistor serves multiple functions: it controls the body voltage of the driving transistor, acts as a switch for the body capacitor, and participates in the overall pixel switching mechanism. By making the body transistor multi-functional, the patent reduces the need for additional dedicated components while achieving reliable threshold voltage compensation.
Solution Approach 2:
The body voltage compensation function is merged into the existing pixel circuit architecture by utilizing the third node (which already exists for other circuit functions) and integrating the body capacitor and body transistor into the established signal timing and voltage distribution framework. This merging approach minimizes the increase in device complexity while achieving the desired reliability improvement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The compensation of the body voltage in the transistor stabilizes luminance and enhances image quality by mitigating the effects of threshold voltage shifts caused by external charges.
Implementation Method 1
a body capacitor which includes a first terminal connected to the body of the driving transistor and a second terminal
Implementation Method 2
a body transistor which includes a gate which receives a body gate signal, a first terminal connected to the second terminal of the body capacitor, and a second terminal connected to the third node
Data Source
AI summary
A pixel includes a light-emitting element which emits light based on a driving current and includes a first electrode and a second electrode which receives a low power voltage, a driving transistor which generates the driving current and includes a gate connected to a first node, a first terminal connected to a second node, a second terminal connected to a third node, and a body, a body capacitor which includes a first terminal connected to the body of the driving transistor and a second terminal, and a body transistor which includes a gate which receives a body gate signal, a first terminal connected to the second terminal of the body capacitor, and a second terminal connected to the third node.