Wireless Key Location Detection Using Antenna Directivity
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Solution Overview
Problem
Conventional wireless key systems face challenges in accurately determining the location of a wireless key relative to a main body due to signal intensity variations caused by reflection, noise, and crosstalk from multiple antennas, leading to complex processes for correct determination.
Innovation Solution
A wireless key system utilizing inner and outer antennas with different directivities for signal transmission and reception, where the wireless key determines its location by selecting an antenna with the highest signal level and comparing it to an antenna with the same directivity as the inner antenna, allowing for simple and accurate location determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If signal intensity measurement is used to determine wireless key location, then location determination can be performed, but the determination accuracy deteriorates due to signal reflection, noise, and crosstalk from multiple antennas
Solution Approach 1:
Instead of using signal intensity measurement to determine location (which is unreliable due to reflection and noise), the patent inverts the approach by using the absence of signal reception as the determination criterion. The wireless key determines it is inside the vehicle when it cannot receive the LF signal from the outer antenna, leveraging the shielding effect rather than fighting against it.
Solution Approach 2:
The patent converts the harmful effect of signal reflection and noise into a beneficial determination mechanism. The shielding effect that causes signal blockage is transformed into a reliable location indicator: when the wireless key is inside the vehicle, the vehicle body shields the LF signal from the outer antenna, and this signal absence is used to confirm indoor location.
2Adaptability or versatility
If multiple transmitting antennas are used for wireless communication, then communication coverage is improved, but signal interference and crosstalk increase making accurate location determination difficult
Solution Approach 1:
The patent segments the location determination function into two independent parts: one using the outer antenna for general communication coverage and another using the inner antenna for accurate location determination. The inner antenna's signal, which is less susceptible to interference, is specifically used for determining whether the key is inside or outside the vehicle.
Solution Approach 2:
The patent introduces the vehicle body as an intermediary element in the location determination process. The vehicle body acts as a shield that blocks the LF signal from the outer antenna when the key is inside, creating a clear distinction between indoor and outdoor locations without requiring direct signal measurement through the noisy environment.
3Loss of information
If signal intensity-based location determination is used, then location information can be obtained, but the process becomes complicated requiring pre-measured data and stored relationships
Solution Approach 1:
The patent enables the wireless key to autonomously determine its location using a simple signal reception check without requiring external pre-measured data or complex processing. The determination is self-contained: the key attempts to receive the LF signal, and based on whether reception succeeds or fails, it independently concludes its location status.
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 correct determination of the wireless key's location inside or outside the main body through a straightforward process, improving the reliability of locking and unlocking operations.
Implementation Method 1
a component which transmits a wireless signal through an inner antenna provided inside the main body and an outer antenna provided outside the main body
Implementation Method 2
a determination component which determines whether the wireless signal has been received by any one of antennas having different directivities, a measuring component which measures a direction of movement of the wireless key
Data Source
AI summary
A wireless key system and location detection method determine whether a wireless key is located inside or outside a main body. A communication device in the main body transmits a wireless signal using an inner antenna and an outer antenna outside the main body having a different directivity. A wireless key measures direction of movement of the wireless key when the wireless signal is received by one of antennas having different directivities, detects one of the antennas receiving the highest signal level of the wireless signal as a first antenna, selects one of the antennas having the same directivity as the inner antenna as a second antenna according to the measured direction of movement and detected directivity of the antenna, and decides that the wireless key is inside the main body based on the signal levels of the wireless signals received by the first and second antennas.