Camera-to-Display Latency Measurement Using Simulated Touch
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Solution Overview
Problem
Conventional methods for determining camera-to-display latency in mobile devices are expensive and complex, making it difficult to quickly characterize this temporal delay between image capture by a camera and image rendering on a touch-sensitive display.
Innovation Solution
A system and method using optically activated touch technology with Cadmium Sulfide photocells to simulate touches on a touch-sensitive display, allowing for the measurement of camera-to-display latency by logging touch reports from both simulated and display-generated touches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical-event timing equipment is used to measure camera-to-display latency, then measurement precision can be achieved, but device complexity and cost increase significantly
Solution Approach 1:
The patent creates a simulated touch event that copies the electrical signal characteristics of a real touch without requiring complex optical timing equipment. The simulated touch is generated by activating a pixel at a known time and measuring the resulting touch report timestamp, providing a simple alternative to conventional optical measurement systems
Solution Approach 2:
The patent replaces complex optical-mechanical timing equipment with an electrical/electronic solution. Instead of using optical sensors and mechanical timing devices, the system uses electrical signal generation through pixel activation and electronic timestamp recording from touch reports, significantly simplifying the measurement system
2Measurement precision
If conventional optical-event timing equipment is used to measure camera-to-display latency, then accurate timing data can be obtained, but the ease of operation deteriorates due to complex setup and operation
Solution Approach 1:
The system uses the device's own display and touch reporting mechanisms to perform the measurement. The display generates the test stimulus and the touch controller provides the timing data, eliminating the need for external complex equipment and simplifying operation to programming and data logging steps
Solution Approach 2:
By creating a simulated touch that copies real touch electrical characteristics, the system enables measurement using the device's existing touch reporting infrastructure, making the process easier to operate compared to setting up and calibrating external optical timing equipment
3Adaptability or versatility
If high-resolution camera and touch-sensitive display components are used, then functional capabilities are improved, but the temporal latency between image capture and display rendering increases
Solution Approach 1:
The system performs preliminary characterization of the camera-to-display latency during device operation. By measuring the timestamp difference between simulated touch activation and touch report generation, the system establishes a baseline latency value that can be used for timing compensation in application software, allowing high-resolution components to operate with optimized timing
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
Enables fast and simple measurement of camera-to-display latency, reducing the need for expensive equipment and providing a rapid quantitative analysis of device performance.
Implementation Method 1
A first light emitting diode 120 and a second light emitting diode 122 are connected in series between first and second terminals 126, 128, respectively, of a flash controller module 130. The first light emitting diode 120 and the second light emitting diode 122 are positioned so that light 136, 138 from the light emitting diodes 120, 122 can be received, respectively, by the camera 134 and a Cadmium Sulfide photocell 102
Data Source
AI summary
A method and system for determining a camera-to-display latency of an electronic device (100) having a camera (134) and touch-sensitive display (108) are disclosed. In one example embodiment, the method (500) includes receiving (511) first light (136) at the camera, and essentially simultaneously receiving second light (138) at a first photosensitive structural portion (102, 602). The method (500) further includes detecting (512) a first simulated touch input at the display (108) in response to a first actuation of the first photosensitive structural portion (102, 602), receiving third light (140) at a second photosensitive structural portion (104, 604), the third light being generated based at least indirectly upon the received first light (136), detecting (514) a second simulated touch input at the display (108) as a result of the receiving of the third light (140), and determining the camera-to-display latency based at least indirectly upon the touch inputs (516).