Photoelectric Sensor PWM Control for Object Detection
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Solution Overview
Problem
Existing photoelectric sensors face challenges in accurately detecting the presence, absence, proximity, or distance of objects with different types, dimensions, and reflectivity.
Innovation Solution
A photoelectric sensor system utilizing pulse-width modulation (PWM) to emit pulsed light, with a duty cycle adjustable to control the average intensity of the light, calibrated for specific object types and effective ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous light is emitted by the photoelectric sensor, then the detection capability is improved, but the energy consumption increases and the ability to distinguish objects with different reflectivity deteriorates
Solution Approach 1:
The patent applies periodic action by emitting light in pulsed intervals rather than continuously. The control circuit generates periodic pulse signals to drive the light-emitting component, creating alternating periods of light emission and non-emission. This periodic operation reduces energy consumption while maintaining detection capability through the use of integration circuits that accumulate optical signals over multiple pulses.
2Length of stationary object
If higher intensity light is emitted to improve detection range, then the effective range is extended, but the energy consumption increases and the ability to detect objects with varying reflectivity deteriorates
Solution Approach 1:
The system uses periodic pulsed light emission where the light is emitted in short bursts at high intensity followed by periods of non-emission. This allows the sensor to achieve extended detection range during the pulse periods while consuming energy only during these brief intervals, rather than maintaining continuous high-intensity emission.
Solution Approach 2:
The patent implements dynamic operation by varying the light emission intensity and duration based on detection requirements. The control circuit dynamically adjusts the pulse width and frequency to optimize the balance between detection range and energy consumption, allowing the system to adapt to different operating conditions.
3Length of stationary object
If the light intensity is increased to detect objects at greater distances, then the detection range is extended, but the ability to accurately detect objects with different reflectivity deteriorates
Solution Approach 1:
The periodic pulsed emission allows the integration circuit to accumulate optical signals from multiple pulses, improving the signal-to-noise ratio for detecting objects with varying reflectivity. The regular timing of pulses provides consistent sampling intervals that enhance the precision of reflectivity measurements across different object types.
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 system effectively detects the presence of objects by converting reflections of pulsed light into electrical signals, providing accurate proximity sensing regardless of object type or dimension.
Implementation Method 1
a photoelectric receiver configured to receive a reflection of the pulsed light off of the object in proximity of the photoelectric sensor, and convert the reflection of the pulsed light to an electrical signal
Data Source
AI summary
A tool storage system is provided that includes a drawer, and an optical system configured to detect presence of an object in the drawer. The optical system includes a photoelectric sensor and processing circuitry. The photoelectric sensor includes a light transmitter configured to emit pulsed light, and a photoelectric receiver configured to convert a reflection of the pulsed light off of the object to an electrical signal that indicates proximity of the object and thereby the presence of the object in the drawer. The processing circuitry is configured to output a pulse-width modulation (PWM) signal from which the light transmitter is driven to emit the pulsed light. The PWM signal has a duty cycle that is adjustable to control an average intensity of the pulsed light, the duty cycle calibrated for a type of the object and an effective range of the photoelectric sensor.