Electro-Optical Device Enable Line Segmentation for Gray Scale Control
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Solution Overview
Problem
Existing organic electro luminescence (EL) devices face challenges in accurately expressing gray scales due to variations in voltage-current characteristics and threshold voltage of driving transistors, leading to low display quality with brightness variations and color deviations between pixels.
Innovation Solution
The electro-optical device incorporates a pixel circuit with a memory circuit and control circuit, utilizing a digital driving method where light-emitting elements are set to either emission or non-emission states, with a unique enable line configuration that allows for precise control of light emission periods, reducing the number of enable lines and improving manufacturing yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a typical organic EL device uses analog driving with a single enable line, then the device structure is simple, but the display quality is low due to brightness variation and gray scale deviation between pixels
Solution Approach 1:
The enable lines are segmented into multiple groups (first enable lines and second enable lines) that are selectively activated in different time periods. This segmentation allows different pixel circuits to receive enable signals at different times, preventing simultaneous light emission during signal writing and enabling precise gray scale control through time-division multiplexing.
Solution Approach 2:
The patent implements periodic activation of enable lines where first enable lines are activated during first time periods and second enable lines are activated during second time periods. This periodic action creates distinct light emission and non-light emission periods, allowing sequential writing of image signals to memory circuits while maintaining stable display output.
2Ease of operation
If the light-emitting element switches between emission and non-emission states during signal writing to memory circuit, then the control is flexible, but the light emission period cannot be strictly controlled affecting gray scale accuracy
Solution Approach 1:
The patent applies preliminary action by controlling the enable lines to be inactivated during the period when image signals are being written to the memory circuits. This preliminary control prevents the light-emitting elements from emitting light during signal writing, ensuring that the light emission period is strictly controlled and gray scale accuracy is maintained before the actual display period begins.
3Measurement precision
If multiple enable lines are used for precise control of light emission periods, then the gray scale control is accurate, but the number of enable lines increases reducing manufacturing yield
Solution Approach 1:
The enable lines are designed with multi-functionality where each enable line serves multiple purposes: controlling light emission timing, enabling signal writing to memory circuits, and defining gray scale periods. This universal design allows precise gray scale control to be achieved without proportionally increasing the number of enable lines, thereby maintaining manufacturing yield.
Solution Approach 2:
The patent implements dynamic control where the activation and inactivation of enable lines is temporally varied. First enable lines and second enable lines are dynamically switched between active and inactive states at different time periods, allowing precise control of light emission periods and gray scale representation without requiring a static increase in the number of enable lines.
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
This configuration enables high-resolution, multi-gray scale displays with reduced power consumption and minimized brightness and color variations, achieving improved display quality and efficiency.
Implementation Method 1
an organic EL device is used... the organic EL element emits light at a luminance in accordance with the amount of current
Data Source
AI summary
Provided are a scan line, a data line, a pixel circuit provided corresponding to an intersection between the scan line and the data line, and an enable line. The pixel circuit includes a memory circuit, a light-emitting element, and an enable line driving circuit, the light-emitting element changes luminance in accordance with an image signal retained in the memory circuit, the enable line driving circuit controls a light emission enabled state of the light-emitting element, the pixel circuit includes a first pixel circuit, a second pixel circuit, a third pixel circuit, and a fourth pixel circuit, the enable line includes a first enable line and a second enable line, the first pixel circuit and the second pixel circuit are electrically connected with the first enable line, and the third pixel circuit and the fourth pixel circuit are electrically connected with the second enable line.