Radio-Wave Sensor Signal Processing for Stationary Object Detection
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Solution Overview
Problem
Conventional sensor devices using a phase difference of 90 degrees for determining object presence or absence suffer from reduced sensing accuracy when the object is in a stationary or generally stationary state, leading to potential malfunctions such as incorrect toilet seat closure during urination.
Innovation Solution
A sensor device with a transmitter and receiver part generating first and second output signals with a phase difference, and a third output signal generated via a differential amplifier circuit from these, improves sensing accuracy by providing a larger amplitude signal for determining object presence or absence, thus preventing malfunctions like incorrect toilet seat closure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two output signals with a phase difference of 90 degrees are used for object detection, then distortion in the output signals is lowered and approaching/leaving of the sensing target can be determined accurately, but sensing accuracy is lowered when the object is in a stationary or generally stationary state
Solution Approach 1:
The patent segments the detection function by creating three separate output signals (first, second, and third signals) instead of relying on a single phase-difference signal. The third output signal is specifically generated to address the stationary object detection problem, while the first two signals maintain the 90-degree phase difference for moving object detection. This segmentation allows each signal to specialize in different detection scenarios.
Solution Approach 2:
The patent adds another dimension to the signal processing by introducing a third output signal that combines the first and second signals through addition. This creates a new detection dimension that is orthogonal to the traditional phase-difference approach, enabling detection of stationary objects that were previously undetectable by the phase-difference method alone.
2Stability of the object's composition
If a phase difference of 90 degrees is maintained between output signals, then distortion is reduced, but locations with small amount of change in output signals are formed depending on distance, reducing sensing accuracy
Solution Approach 1:
The patent changes the signal parameter by introducing a third output signal that is the sum of the first and second signals. This parameter change creates a signal with different amplitude characteristics that compensates for the low-change locations problem. The third signal provides larger amplitude variations even at distances where the phase-difference signals show minimal change.
3Device complexity
If only two output signals with phase difference are used, then device complexity is reduced, but sensing accuracy for stationary objects is insufficient leading to malfunctions
Solution Approach 1:
The patent merges the first and second output signals through addition to generate the third output signal. This merging operation is simple and does not require complex circuitry, yet it produces a signal that significantly improves stationary object detection. The combination of signals creates constructive interference that enhances the amplitude for stationary object detection.
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 proposed solution enhances sensing accuracy and productivity by generating a third output signal with a larger amplitude, allowing for more accurate detection of user behavior, even in stationary states, thereby preventing malfunctions like automatic toilet seat closure during urination.
Implementation Method 1
a receiver part configured to receive a reflection wave reflected by a sensing object as a reception wave
Implementation Method 2
a mixer part for generating output signals obtained by interference of the reception waves
Data Source
AI summary
According to one embodiment, a sensor device includes a transmitter part, a receiver part, a signal generation part, and a determination part. The transmitter part is configured to emit a radio wave outside as a transmission wave. The receiver part is configured to receive a reflection wave reflected by an object as a reception wave. The signal generation part is configured to generate a first output signal generated based on the transmission wave and the reception wave, a second output signal provided with a phase different from that of the first output signal, and a third output signal generated based on the first output signal and the second output signal. The determination part is configured to determine presence or absence of an object based on the first output signal, the second output signal, and the third output signal.