Digitally Variable Resistor for LCD VCOM Voltage Control
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Solution Overview
Problem
Current driver circuitry for display panels, particularly LCDs, faces challenges in achieving precise VCOM voltage settings to minimize flickering and extend panel lifetime, while existing solutions require external resistors that are costly and temperature-dependent, limiting accuracy and compatibility with production equipment.
Innovation Solution
A 7-bit digitally variable resistor or programmable VCOM circuit with integrated resistors and a programmable current setting resistor, which reduces the number of external components, pins, and enhances accuracy by relying solely on internal resistor ratios, allowing precise VCOM voltage adjustments and compatibility with existing production machinery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If external resistors are used for VCOM voltage setting, then flexibility and adjustability are improved, but cost increases and temperature dependence reduces accuracy
Solution Approach 1:
The patent merges the external resistor components into internal resistors integrated within the driver circuitry. This integration eliminates the need for separate external resistors while maintaining the ability to adjust VCOM voltage through digital control of the integrated resistive elements, thereby resolving the contradiction between adaptability and precision.
Solution Approach 2:
The patent extracts the temperature-dependent external resistors from the system and replaces them with temperature-stable internal resistors. This extraction eliminates the source of temperature-induced accuracy degradation while preserving the voltage adjustment capability through digital control mechanisms.
2Adaptability or versatility
If external resistors are used for VCOM voltage setting, then voltage adjustment flexibility is improved, but the number of external components and pins increases
Solution Approach 1:
The patent combines multiple external components (resistors and associated pins) into a single integrated circuit block. The VCOM adjustment functionality is achieved through digital control signals that manipulate internal resistive elements, eliminating the need for multiple external components and reducing pin count while maintaining adjustability.
Solution Approach 2:
The integrated driver circuitry performs multiple functions including VCOM voltage generation, voltage adjustment, and digital control within a single device. This multi-functionality eliminates the need for separate external resistors and control mechanisms, reducing overall system complexity while preserving flexibility.
3Ease of operation
If external resistors are used for VCOM voltage setting, then initial setup flexibility is improved, but compatibility with automated production equipment is reduced
Solution Approach 1:
The patent replaces manual resistor selection and wiring (mechanical/setup process) with digital control signals that automatically configure the VCOM voltage. This substitution enables automated production equipment to program the desired voltage settings electronically, improving compatibility with automated manufacturing while maintaining setup flexibility through digital programming.
Solution Approach 2:
The patent incorporates preliminary digital control mechanisms that allow VCOM voltage settings to be programmed in advance during the manufacturing process. This preliminary configuration capability enables automated production equipment to set optimal voltage parameters before the display device is deployed, facilitating both ease of manufacture and operational flexibility.
Data Source
AI summary
One or more resistors or resistances are integrated in a 7-bit DVR or PVCOM integrated circuit. A 7-bit DVR or PVCOM integrated circuit includes a 7-bit DAC. The integrated resistors or resistances (R1, R2, or RSET, or any combination) reduces the number of external components, reduces the number of pins, and increases the accuracy of the DVR or PVCOM circuit. The least significant bit (LSB) of the DAC depends only on ratios of internal resistors, which can be made very accurate and independent of temperature.