Optical Key Detection Circuit Simplification via Signal Level Selection
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Solution Overview
Problem
Existing optical detection devices for keyboard instruments face complexity due to variability in light reception levels of light receivers, requiring voltage-dividing circuits and multiplexers to adjust light emission levels, which complicates the device configuration and does not accurately compensate for these variabilities.
Innovation Solution
A detection device with light emitters and receivers that adjust light emission levels within each emission period by varying the signal level of the driving signal, allowing for the selection of light reception levels during each unit period as detected values, thereby compensating for receiver variability without the need for additional circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage-dividing circuits and multiplexers are used to adjust light emission levels, then light reception level variability is compensated, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates the voltage-dividing circuit and multiplexer from the system. Instead of using these complex circuits to generate multiple light reception signals, the invention directly selects the appropriate light reception signal based on the light emitter's emission level, thereby removing the problematic components while maintaining detection accuracy.
Solution Approach 2:
The light receiver is made universal by enabling it to directly output light reception signals that can be selected based on different light emission levels. The single light receiver serves multiple detection purposes across different key positions without requiring separate voltage-dividing circuits for each combination, achieving multi-functionality with minimal components.
2Reliability
If voltage-dividing circuits are used to generate light reception signals, then light reception level variability is addressed, but the number of circuit components increases
Solution Approach 1:
The patent removes the voltage-dividing circuit entirely from the system. The light receiver directly generates the light reception signal without passing it through a voltage-dividing circuit, thereby eliminating the need for multiple resistive elements while maintaining the ability to compensate for light reception level variability.
Solution Approach 2:
The light receiver performs its own signal conditioning and directly outputs the light reception signal at the appropriate level. The system uses the natural characteristics of the light receiver to provide the necessary signal levels without requiring external voltage-dividing circuits, achieving self-service functionality.
3Measurement precision
If multiplexers are used to select light reception signals, then variability compensation is achieved, but device complexity and component count increase
Solution Approach 1:
The patent extracts and eliminates the multiplexer from the signal selection process. Instead of using a multiplexer to sequentially select light reception signals, the invention directly routes the appropriate light reception signal to the output based on which light emitter is currently emitting light, thereby removing the multiplexer while maintaining accurate signal selection.
Solution Approach 2:
The control circuit acts as an intelligent intermediary that directly routes the appropriate light reception signal from the light receiver to the output based on the current light emitter's emission level. This eliminates the need for a multiplexer by using a more direct control approach that reduces component complexity.
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 approach allows for accurate detection of key movement in keyboard instruments while simplifying the device configuration by eliminating the need for voltage-dividing circuits and multiplexers, ensuring reliable operation with reduced complexity.
Implementation Method 1
a light emitter in the movement detector emits light in different emission levels in accordance with a signal level of a driving signal provided to the light emitter
Implementation Method 2
a light receiver in the movement detector generates a light reception level in accordance with an amount of received light
Data Source
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AI summary
A detection device includes: a movement detector configured to include light emitters and light receivers, wherein in accordance with movement of a moving body among moving bodies, each moving body corresponding to a different combination of one of the light emitters and one of the light receivers, a light reception level of the light receiver in a combination corresponding to the moving body changes; a light emission controller configured to cause each of the light emitters to sequentially emit light in each light emission period by providing a driving signal, and to cause a signal level of the driving signal to differ between unit periods within the light emission period; and a detected value selector configured to select, for each light emission period, a light reception level in one of the unit periods within the light emission period as a detected value for each of the light receivers.