Semiconductor Pixel Structure for High Aperture Ratio
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Solution Overview
Problem
In display devices with self-luminous pixels, such as OLEDs, the aperture ratio is limited by the number of transistors and wires, which affects luminosity and definition, as increased definition reduces luminosity and requires higher driving voltage, and existing analog gradation methods are prone to variations in transistor characteristics.
Innovation Solution
A semiconductor device structure that reduces the number of transistors and wires by using a potential supply line to control the light emitting element's voltage without a switch, incorporating a transistor with a gate terminal, first and second terminals, wires, and a capacitor or switch to manage potential differences and conductivity, allowing for improved aperture ratio and luminosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of transistors and wires in a pixel is increased to improve definition, then the definition is improved, but the aperture ratio decreases and luminosity is reduced
Solution Approach 1:
The patent extracts and removes unnecessary transistors and wiring from the pixel structure. Specifically, it eliminates the need for separate switching transistors by using a capacitor to hold the gate potential, and removes redundant power supply lines by using a single potential supply line that is controlled through the capacitor. This extraction of unnecessary components directly increases the aperture ratio while maintaining definition.
Solution Approach 2:
The patent makes the capacitor serve multiple functions: it acts as both a storage element for the gate potential and as a switching mechanism. The single potential supply line serves dual purposes by providing both power and control signals. This multi-functionality reduces the number of components needed, thereby increasing the aperture ratio without compromising definition.
2Illumination intensity
If the aperture ratio is increased to improve luminosity, then the luminosity is improved, but the number of transistors and wires must be reduced
Solution Approach 1:
The patent extracts and removes unnecessary transistors and wiring from the pixel structure. Specifically, it eliminates the need for separate switching transistors by using a capacitor to hold the gate potential, and removes redundant power supply lines by using a single potential supply line that is controlled through the capacitor. This extraction of unnecessary components directly increases the aperture ratio while maintaining definition.
Solution Approach 2:
The patent makes the capacitor serve multiple functions: it acts as both a storage element for the gate potential and as a switching mechanism. The single potential supply line serves dual purposes by providing both power and control signals. This multi-functionality reduces the number of components needed, thereby increasing the aperture ratio without compromising definition.
3Use of energy by moving object
If analog control method is used to reduce power consumption, then power consumption is reduced, but uniformity of luminance varies due to transistor characteristics
Solution Approach 1:
The patent replaces the mechanical/electronic switching system (transistors) with an electrical field-based system (capacitor). By using a capacitor to hold the gate potential and control the light emitting element, the system eliminates the need for continuous transistor switching, thereby reducing power consumption while achieving uniform luminance control that is independent of transistor characteristics.
4Reliability
If digital control method is used to improve uniformity of luminance, then uniformity is improved, but frequency must be increased and power consumption becomes large
Solution Approach 1:
The patent uses periodic action by controlling the light emitting element through time-based potential holding. The capacitor holds the gate potential for the duration of the light emitting period, creating a time-gated control mechanism. This periodic control achieves uniform luminance like digital methods but at lower frequencies and with significantly reduced power consumption compared to continuous digital switching.
Data Source
AI summary
When light emitting elements have the same luminance, luminosity obtained from one pixel can be higher as area of a light emitting region in the pixel (also called an aperture ration) is increased. The aperture ratio of a pixel is low if the number of transistors and wires constituting the pixel is large. Thus, the invention is to decrease the number of transistors and wires constituting a pixel to increase the aperture ratio. Instead of a power supply line to which a certain potential is set, a potential supply line which controls a potential by a signal is provided; supplying an applied voltage to a light emitting element can be controlled by a signal of the potential supply line without providing a switch.