Optical Time Sync via LED Flashlight and Photodiode
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Solution Overview
Problem
Existing methods for setting clocks are cumbersome, prone to errors, and costly due to the need for manual adjustments and complex signal reception technologies, especially for devices without internal calendars, leading to inaccuracies and inconsistent user interfaces.
Innovation Solution
A method using a mobile electronic device to encode current time information into a light signal, which is transmitted via a high-brightness LED flash and received by a light sensor in the clock, allowing for automatic and precise time setting without user expertise or specialized knowledge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If radio time signals (DCF77), GPS signals or RDS radio signals are used for automatic time setting, then time setting automation is improved, but device complexity and production cost increase due to required reception sensitivity and technical complexity
Solution Approach 1:
The patent replaces complex radio signal reception systems with a simple optical communication system. Instead of using radio frequency receivers (DCF77, GPS, RDS) that require high sensitivity and complex processing, the invention uses an LED flashlight to transmit encoded time information via light intensity modulation, which is detected by a simple photodiode or phototransistor in the clock. This substitution dramatically reduces device complexity while maintaining automation.
Solution Approach 2:
The patent employs inexpensive optical components (LED flashlight and photodiode/phototransistor) instead of expensive radio reception systems. The mobile device's built-in flashlight and the clock's simple light sensor are成本低廉 components that eliminate the need for specialized radio receivers, thereby reducing production costs while achieving automatic time synchronization.
2Extent of automation
If radio time signals (DCF77), GPS signals or RDS radio signals are used for automatic time setting, then time setting automation is improved, but reliability deteriorates due to reception problems from fluctuating signal strengths
Solution Approach 1:
The patent replaces unreliable radio signal reception with a robust optical transmission system. The LED flashlight emits strong, controllable light signals that are easily detected by the photodiode or phototransistor. The light intensity modulation clearly encodes time information without suffering from the signal strength fluctuations that plague radio-based systems, especially indoors, thereby significantly improving reception reliability.
3Extent of automation
If radio time signals (DCF77), GPS signals or RDS radio signals are used for automatic time setting, then time setting automation is improved, but adaptability deteriorates due to lack of internationally uniform standards and inability to receive signals in many areas
Solution Approach 1:
The patent creates a universal time setting system that works globally without depending on location-specific radio signals. The optical communication method using LED flashlight and photodiode can be deployed anywhere in the world, eliminating the geographical limitations of DCF77 (Europe), GPS (Americas), and RDS (Europe) systems. This universal approach allows any clock with a light sensor to receive time signals from any mobile device with a flashlight, regardless of location.
4Device complexity
If manual time setting is used, then device complexity is reduced, but productivity deteriorates due to the need for repeated adjustments of multiple clocks
Solution Approach 1:
The patent replaces manual time setting operations with an automated optical communication system. The mobile device automatically encodes time information and transmits it via LED flashlight, while the clock's photodiode automatically detects and processes the signal. This eliminates the need for users to manually adjust multiple clocks, dramatically improving productivity while keeping the clock's hardware simple and inexpensive.
5Ease of operation
If light intensity modulation is used for data transmission, then ease of operation is improved, but measurement precision deteriorates due to sensitivity to ambient light fluctuations
Solution Approach 1:
The patent uses periodic light intensity modulation to encode time information, creating distinct light pulses that represent binary data. This periodic signaling creates clear, distinguishable patterns that are easier to detect and less susceptible to ambient light interference compared to continuous modulation. The pulsed nature of the signal allows the photodiode to distinguish between signal and background light more effectively.
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 method simplifies clock setting, reduces costs by using inexpensive components, and ensures atomic-accurate timekeeping with minimal user interaction, while being insensitive to ambient light fluctuations and signal strength issues.
Implementation Method 1
controlling a flashlight (12) of the mobile electronic device (10) such that a light signal (14) is emitted with a brightness varying according to the bit sequence. The flashlight is, in particular, an LED flashlight
Implementation Method 2
The clock (16) has a light sensor (20), in particular a photodiode or phototransistor, with which the light signal (14) is received
Data Source
Figure 1
AI summary
Method for setting a clock comprising the following steps: • Encoding information about the current time as a bit sequence, wherein the information includes an hour, minute, and second indication of the current time, • Controlling a flashlight of a mobile electronic device such that a light signal with varying brightness according to the bit sequence is emitted, • Receiving the light signal with a light sensor of the clock, • Decoding the light signal, and • Setting the clock according to the information about the current time contained in the light signal.