Light-to-Frequency Sensor Hold Operation Error Correction
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Solution Overview
Problem
Light-to-frequency sensors face measurement inaccuracies due to hold operations, which disconnect and reconnect a diode from an operational amplifier, causing errors in light intensity measurement, especially when multiple hold operations are performed.
Innovation Solution
The sensor integrates light signals across multiple clock cycles, performs a hold operation to stop integration, and resumes integration after a delay, summing the initial and resumed integration cycles to correct for errors, thereby maintaining accurate light measurement regardless of the number of hold operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a hold operation is performed to stop integration during background light emission, then measurement accuracy is improved, but errors are introduced when the diode is reconnected to the operational amplifier
Solution Approach 1:
The patent applies preliminary action by performing an initialization period after the diode is reconnected to the operational amplifier. During this initialization period, the system prepares the integration circuit before actual light measurement begins, ensuring that the circuit is properly conditioned and ready for accurate measurements. This preliminary preparation eliminates connection errors by establishing a stable baseline state before measurement starts.
2Measurement precision
If the diode is disconnected during hold operations to avoid background light interference, then light measurement accuracy is improved, but the digital output waveform is disturbed during connection and reconnection
Solution Approach 1:
The patent extracts the problematic connection/reconnection operations from the active measurement process by implementing a hold operation. During the hold operation, the diode is disconnected from the operational amplifier, removing the source of waveform disturbances. The measurement process is paused during these connection operations, and only resumes after proper initialization, thereby eliminating the harmful waveform errors from the measurement data.
3Reliability
If multiple hold operations are performed to maintain accurate measurements, then measurement reliability is improved, but the frequency of connection and reconnection increases causing more errors
Solution Approach 1:
The patent applies partial action by implementing a fixed initialization period after each hold operation, regardless of whether the connection errors would have significantly impacted the measurement. This initialization period is always executed to ensure proper circuit conditioning, even though it adds time overhead. The approach accepts some time loss to guarantee measurement reliability, using a standardized initialization sequence that can be efficiently implemented in hardware.
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 significantly reduces errors induced by hold operations to less than one count, ensuring consistent accuracy in light measurement across various light conditions and frequencies of hold operations, without requiring additional analog circuits.
Implementation Method 1
The light-to-frequency sensor includes a diode and an integration circuit
Implementation Method 2
an integration circuit. During the hold operation, the light sensor disconnects the diode from a negative input of an operational amplifier in the integration circuit
Data Source
AI summary
Methods, systems, and apparatus, including computer programs encoded on computer storage media, for a light-to-frequency sensor conversion. In some implementations, a first output waveform is generated from a light signal, a frequency of the first output waveform being based on an intensity of the light signal, including integrating the light signal across multiple clock cycles. In response to receiving a notification, a hold operation is performed to stop integrating the light signal for a period of time. In response to an end of the hold operation, a second output waveform is generated that includes integrating the intensity of the light signal starting from the end of the hold operation over a count of the multiple clock cycles that start after the end of the hold operation by a delay amount. The first output waveform and the second output waveform are summed to determine the intensity of the light signal.