Photoelectric Encoder Light Control for Power Efficiency
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Solution Overview
Problem
Photoelectric encoders face increased power consumption when attempting to enhance light source intensity to improve measurement accuracy, leading to inefficiencies and higher noise levels when Lissajous signal amplitudes are low.
Innovation Solution
Incorporating a light amount control unit that determines errors in Lissajous signals and suppresses light source power by turning off or reducing the light source when errors are detected, along with a return control unit that reactivates the light source based on predetermined triggers or movements, to maintain optimal power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrical current to the light source is increased to enhance light amount and improve measurement accuracy, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent implements dynamic control of the light source by introducing a light amount control unit that adjusts electrical current in real-time based on detected Lissajous signal amplitude. The system transitions from static fixed current operation to dynamic adaptive current adjustment, allowing the light source to operate at optimal current levels that vary with measurement conditions, thereby resolving the contradiction between measurement precision and power consumption.
Solution Approach 2:
The patent employs feedback control through the light amount control unit that continuously monitors the amplitude of Lissajous signals detected by the light receiving unit and adjusts the electrical current supplied to the light source accordingly. This closed-loop feedback mechanism ensures the light source operates at the minimum necessary current to maintain adequate signal amplitude, simultaneously achieving measurement precision and energy efficiency.
2Measurement precision
If light amount of the light source is increased to improve signal amplitude, then measurement precision is improved, but the light source life decreases
Solution Approach 1:
The patent applies dynamic current adjustment to extend light source life by avoiding continuous operation at high current levels. The light amount control unit modulates the electrical current based on real-time signal quality, allowing the light source to operate at lower currents during periods when maximum measurement precision is not critical, thereby reducing thermal stress and extending the operational lifespan of the light source.
Solution Approach 2:
The patent implements periodic or intermittent high-current operation rather than continuous high-current operation. The light amount control unit activates high current only when the detected Lissajous signal amplitude falls below a threshold, and reduces or stops current when signal quality is adequate, creating a periodic operation pattern that extends light source life while maintaining measurement precision when needed.
3Measurement precision
If electrical current to the light source is continuously increased to maintain signal amplitude, then measurement precision is maintained, but excess power supply occurs
Solution Approach 1:
The patent applies partial action by supplying only the necessary electrical current to achieve adequate signal amplitude rather than continuous excessive current supply. The light amount control unit carefully calibrates the current level to match the actual measurement requirements, avoiding both insufficient current (which would degrade precision) and excessive current (which would waste energy), thereby optimizing the balance between measurement precision and energy efficiency.
Solution Approach 2:
The patent utilizes parameter changes by dynamically adjusting the electrical current parameter based on the amplitude parameter of the detected Lissajous signals. The light amount control unit establishes a relationship between signal amplitude and required current, continuously modifying the current parameter to maintain optimal signal quality while minimizing power consumption, thus eliminating excess power supply.
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 configuration reduces power consumption by preventing excessive power supply to the light source while ensuring reliable signal detection, extending the life of light sources like LEDs through controlled blinking.
Implementation Method 1
a light receiving unit configured to receive, via the scale, light emitted from a light source
Data Source
AI summary
An encoder includes a scale having graduations arranged in a measurement direction, a head including a light receiving unit configured to receive, via the scale, light emitted from a light source, and being configured to detect a relative movement amount with respect to the scale by relatively moving in the measurement direction of the scale, and a control unit configured to control the head. The control unit includes a light amount control unit configured to perform control so as to keep a predetermined light receiving amount by increasing or decreasing a light amount of the light source, an error determination unit configured to determine an error based on light received by the light receiving unit, and a light amount suppression unit configured to suppress a light amount of the light source by stopping control performed by the light amount control unit, when the error determination unit determines as an error.