Display Driver PWM Encoding to Cut Gradation Signal Lines
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Solution Overview
Problem
Conventional liquid crystal display (LCD) driver circuits require a large number of signal lines for gradation display, leading to increased area occupation and signal interference, especially when scaling up to higher color depths like 4,096 or 65K colors.
Innovation Solution
The implementation of a PWM signal encoding and decoding method within the display driver IC reduces the number of signal lines by generating (n+1) encoded signals from n original PWM signals, using Boolean algebra expressions to combine adjacent signals and decode them back into the original form, thereby reducing the physical area and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional PWM signal transmission is used for gradation display, then the display can achieve the required color depth, but the number of signal lines increases significantly occupying wide area
Solution Approach 1:
The patent combines multiple PWM signals into a single encoded signal for transmission. The encoder merges 8 PWM signals (for 256 colors) into one encoded signal, and for 65K colors, combines 256 PWM signals into one encoded signal. This merging approach dramatically reduces the number of signal lines required while preserving the ability to achieve the required color depth through decoding at the receiver end.
Solution Approach 2:
The patent introduces an encoder as an intermediary device that transforms multiple PWM signals into a single encoded signal. The encoder acts as a mediator between the signal source and transmission medium, performing the function of signal compression. At the receiving end, a decoder serves as another intermediary to restore the original PWM signals from the encoded signal, enabling faithful signal transmission with minimal line usage.
2Quantity of substance
If more PWM signal lines are used to support higher color depths (4,096 or 65K colors), then the display resolution increases, but signal interference between lines increases
Solution Approach 1:
The patent combines multiple PWM signals into a single encoded signal for transmission. The encoder merges 8 PWM signals (for 256 colors) into one encoded signal, and for 65K colors, combines 256 PWM signals into one encoded signal. This merging approach dramatically reduces the number of signal lines required while preserving the ability to achieve the required color depth through decoding at the receiver end.
Solution Approach 2:
The patent introduces an encoder as an intermediary device that transforms multiple PWM signals into a single encoded signal. The encoder acts as a mediator between the signal source and transmission medium, performing the function of signal compression. At the receiving end, a decoder serves as another intermediary to restore the original PWM signals from the encoded signal, enabling faithful signal transmission with minimal line usage.
3Adaptability or versatility
If the number of colors is increased to 4,096 or 65K colors, then the display capability is enhanced, but the circuit cannot be scaled down due to increased signal lines
Solution Approach 1:
The patent combines multiple PWM signals into a single encoded signal for transmission. The encoder merges 8 PWM signals (for 256 colors) into one encoded signal, and for 65K colors, combines 256 PWM signals into one encoded signal. This merging approach dramatically reduces the number of signal lines required while preserving the ability to achieve the required color depth through decoding at the receiver end.
Solution Approach 2:
The encoder and decoder provide universal functionality that works across different color depth requirements. The same encoding scheme can handle 256 colors, 4,096 colors, or 65K colors by adjusting the number of PWM signals combined, making the system adaptable and scalable without requiring fundamental redesign for different color depth specifications.
Data Source
AI summary
There is provided a technology that can reduce the number of signal lines by encoding a PWM signal used in a display driver IC. The display driver circuit for displaying a gradation on a display screen based on a PWM signal includes a PWM signal generator for generating a PWM signal, a PWM encoder for encoding the PWM signal generated from the PWM signal generator, a PWM decoder for decoding the encoded PWM signal into the PWM signal, a switching unit for selectively outputting the PWM signal generated from the PWM decoder, a data storage unit for storing a display data used to switch the switching unit, and an SRAM decoder for outputting an on/off signal to the switching unit according to the display data outputted from the data storage unit.