Micro OLED Display Demultiplexer Reduces Bonding Pad Count
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Solution Overview
Problem
Display devices used in virtual and augmented reality systems face challenges in image quality due to signal settling errors and increased signal noise from closely spaced bonding pads, which also complicate manufacturing and increase costs when trying to accommodate a large number of OLED pixels and signal lines.
Innovation Solution
Implementing a display device with a reduced number of bonding pads by using a demultiplexer and sample and hold circuits to route data signals to multiple columns of pixels in a time-divisional manner, allowing for efficient data signal sampling, storage, and transfer, thereby reducing signal noise and manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If bonding pads are placed close to each other to reduce chip area, then the area of the chip is reduced, but signal noise increases due to crosstalk
Solution Approach 1:
The invention segments the data signal transmission by introducing sample and hold circuits that sequentially sample data for multiple columns from a single bonding pad. This time-divisional approach divides the signal transmission into discrete segments, allowing one bonding pad to serve multiple columns without continuous signal interference, thereby reducing crosstalk while maintaining compact bonding pad layout
Solution Approach 2:
The sample and hold circuits operate with periodic switching, sequentially connecting to different column groups at regular time intervals. This periodic action allows the bonding pad to transmit data for multiple columns in a time-divisional manner, reducing signal overlap and crosstalk while maintaining efficient data transmission to all columns
2Object-affected harmful factors
If a larger chip is used to accommodate more bonding pads and signal lines, then signal noise is reduced, but the cost and size of the display device increase
Solution Approach 1:
The invention merges the function of multiple bonding pads into a single bonding pad by using sample and hold circuits to sequentially handle data for multiple columns. This consolidation reduces the total number of bonding pads required, allowing smaller chip size while maintaining signal quality through time-divisional signal routing
Solution Approach 2:
The single bonding pad is designed with multi-functionality, serving multiple column groups through the sample and hold circuitry. This universal bonding pad structure performs the function of what would traditionally require multiple dedicated bonding pads, reducing chip area while maintaining adequate signal transmission quality
3Area of stationary object
If adjacent bonding pads are disposed with smaller pitch to reduce chip area, then manufacturing complexity increases
Solution Approach 1:
The invention segments signal transmission in the time domain rather than requiring dense spatial packing of bonding pads. By using sequential sampling and holding, the design achieves area reduction without the manufacturing complexity associated with small-pitch bonding pad arrangements, as the bonding pads can be spaced further apart
4Measurement precision
If high frame rate is used to display high resolution image, then image quality is improved, but signal settling errors increase
Solution Approach 1:
The sample and hold circuits perform preliminary sampling and storage of data signals before they are routed to the respective columns. This preliminary action allows the data to be captured and held at stable voltage levels, reducing signal settling errors that would otherwise occur with high-speed continuous transmission required for high frame rates
Solution Approach 2:
The sample and hold circuits act as intermediaries between the bonding pad and the column data lines. These intermediary circuits buffer and condition the signals, allowing proper signal settling before transmission to the columns, thereby reducing settling errors while maintaining high frame rate operation
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 approach enhances image quality by minimizing signal noise and simplifies manufacturing, while maintaining compactness and reducing costs by allowing for a higher number of OLED pixels without the need for a larger chip.
Implementation Method 1
a plurality of capacitors that stores data signals for the corresponding column of pixels
Data Source
AI summary
Embodiments relate to a display device including bonding pads on a display element where data signals for a plurality of columns of pixels are provided to a same bonding pad in a time-divisional manner. Each of the bonding pads is connected to a plurality of demultiplexer circuits for sampling data signals at the bonding pad, storing the data signals, and transferring the sample data signals to corresponding columns of pixels. Each column of pixels includes a plurality of columns of subpixels, and a period during which a demultiplexer circuit samples the bonding pad for a column of subpixels of a first color may at least partially overlap with a period during which the demultiplexer circuit transfers previously sampled data signals to a column of subpixels of a second color.