Touch Detection Circuit Power Management for LCD Weight Reduction
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Solution Overview
Problem
Liquid crystal display (LCD) devices with integrated touch sensors face challenges in power consumption, particularly in portable devices, due to continuous operation of sensing signal processors, which increases thickness, weight, and reduces the ability to represent fine characters or images effectively.
Innovation Solution
A touch detection system with a power-saving mode that reduces power consumption by selectively powering components based on touch detection, using a light sensing circuit and a physical parameter sensing circuit, with amplifiers, parallel-to-serial converters, and analog-to-digital converters operating at different clock frequencies depending on touch presence, allowing for efficient touch sensing with reduced power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If sensors are incorporated into the LCD to enable touch sensing, then touch detection capability is improved, but the thickness and weight of the LCD increase
Solution Approach 1:
The patent combines the touch sensor array with the liquid crystal display pixel array into a single integrated structure. Each pixel element includes both display functionality and touch sensing capability, allowing the LCD to perform both functions without adding separate sensor layers that would increase weight and thickness.
Solution Approach 2:
The pixel electrodes serve dual purposes: displaying images through liquid crystal modulation and detecting touches through capacitance changes. This multi-functional design eliminates the need for dedicated sensor components, thereby avoiding additional weight while maintaining touch detection capability.
2Reliability
If a sensing signal processor continuously reads signals from sensors, then touch sensing reliability is improved, but power consumption increases
Solution Approach 1:
Instead of continuous signal reading, the patent implements periodic sampling of sensor signals at specific intervals. The sensing signal processor reads sensor data only when needed (e.g., during touch events or at predetermined time intervals), reducing power consumption while maintaining reliable touch detection capability.
Solution Approach 2:
The patent employs dynamic power management where the sensing signal processor operates in different modes: active mode during touch events for reliable detection, and low-power mode during idle periods. This dynamic operation adjusts processing intensity based on actual sensing needs, balancing reliability and power consumption.
3Adaptability or versatility
If sensors are integrated into the LCD, then touch sensing function is added, but the ability to represent fine characters or pictures deteriorates
Solution Approach 1:
The patent divides the display into pixel regions where each region contains both display elements and touch sensing elements. By segmenting the functional components within each pixel region and carefully designing their spatial arrangement, the patent maintains high display resolution for fine characters while integrating touch sensing capability.
Solution Approach 2:
The patent optimizes the local structure of each pixel region to prioritize display quality in areas critical for image rendering while allocating touch sensing elements in positions that minimize impact on visual output. This localized optimization ensures fine display quality is preserved while touch sensing function is enabled.
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
The system enables reliable and accurate touch sensing while minimizing power consumption, particularly beneficial for portable devices like mobile phones and PDAs, by switching between normal and power-saving modes based on touch detection, thus optimizing battery life and display performance.
Implementation Method 1
a light sensing circuit configured to generate a signal indicative of sensed light
Implementation Method 2
a physical parameter sensing circuit configured to generate a signal indicative of a sensed physical parameter
Data Source
AI summary
A display apparatus may include touch detection circuitry including a light sensing circuit and a physical parameter sensing circuit (e.g., a pressure sensing circuit). The display apparatus may further include processing circuitry implementing a power-saving mode and a normal mode, and configured to generate touch information. An display driver may include a photo sensing circuit and a pressure sensing circuit. An embodiment of the display driver may include: an amplifying unit amplifying a photo sensing signal and a pressure sensing signal; a parallel-to-serial converting unit converting the amplified photo sensing signal and the amplified pressure sensing signal into serial sensing signals; and an analog-to-digital converter converting the serial sensing signals into digital sensing signals, wherein the amplifying unit, the parallel-to-serial converting unit, and the analog-to-digital converter operate in one of a normal mode and a power saving mode according to the pressure sensing signal.