Display Device Pixel Area Ratio Gray Level Circuit
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Solution Overview
Problem
The challenge is to develop compact and reliable driving circuits for high-definition display devices that can efficiently convert digital signals to analog signals for gray-level voltage output, while minimizing circuit size and manufacturing costs, and ensuring high transmission opening ratios.
Innovation Solution
The solution involves a display device with pixel sections having multiple pixel electrodes of different areas, where gray levels are assigned based on the area ratio, and a video-signal driving circuit and scanning-signal driving circuit on the same substrate, which divides the scanning period into output periods to supply gray-level voltage to each pixel electrode, reducing the circuit scale and layout space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of bits of display data is increased to achieve higher gray levels, then the gray level precision is improved, but the scale of the D-A conversion circuit increases
Solution Approach 1:
The patent segments the gray level representation by dividing pixels into multiple groups with different area ratios. Instead of using a single D-A conversion circuit to generate all gray levels, the system uses a small D-A conversion circuit (e.g., 2-bit) to generate a limited set of gray levels, then assigns different numbers of pixels to each gray level based on area ratio. This segmentation allows achieving high gray level precision (e.g., 8-bit equivalent) without increasing the D-A conversion circuit scale.
Solution Approach 2:
The patent applies local quality by assigning different areas to different pixel groups within the same pixel section. Each pixel group has a specific area ratio that corresponds to a specific gray level. This local differentiation in pixel area allows the system to encode gray level information spatially rather than through increased circuit complexity.
2Measurement precision
If the number of pixels is increased to achieve higher definition, then the display quality is improved, but the mounting area for driving circuits increases
Solution Approach 1:
The patent merges the driving circuits with the pixel section on the same substrate, eliminating the need for separate mounting areas. The D-A conversion circuit and other driving components are integrated directly into the pixel section structure, allowing high-definition displays with increased pixel counts without proportionally increasing the mounting area for driving circuits.
Solution Approach 2:
The pixel section serves multiple functions: it contains both the display pixels and the driving circuits for controlling those pixels. The same physical structure performs both display and control functions, reducing the overall area required compared to separate mounting of driving circuits.
3Adaptability or versatility
If the pitch of connecting terminals is decreased to increase the number of outputs, then the display capability is improved, but the reliability decreases and manufacturing cost increases
Solution Approach 1:
The patent extracts the D-A conversion function from the pixel section and implements it separately with a small-scale circuit. This extraction allows the pixel section to have fewer, more reliable connecting terminals while still achieving high display capability through the area ratio method. The D-A conversion circuit is removed from the pixel section boundary, reducing the number of terminals needed.
Data Source
AI summary
A display device for use in compact portable devices is configured for assigning gray levels according to the pixel area ratio and, further includes a digital-to-analog (D-A) conversion circuit for converting digital data to gray-level voltage or analog signals. This configuration reduces the size of the circuit for D-A conversion, thus reducing the space for the driving circuit when assigning gray levels according to the pixel area ratio. The combination of the gray-level voltage output from the driving circuit and the gray-level assignment according to the pixel area ratio reduces the scale of the circuit.