Photoelectric Encoder Resolution via Logical Signal Processing
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Solution Overview
Problem
Photoelectric encoders face limitations in resolution and signal-to-noise ratio due to the frequency of the output signal being equal to the movement frequency of the slits, making it difficult to accurately read minute frequency changes and maintain high resolution without reducing the slit pitch, which leads to issues like crosstalk and reduced signal quality.
Innovation Solution
A photoelectric encoder design that includes a light-emitting device and a plurality of light-receiving devices arranged in one direction, with a logical operating section that forms an output signal with a frequency different from the movement frequency by operating on logical values from the light-receiving devices, allowing for improved resolution and accurate detection of movement information without reducing the slit pitch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the slit pitch of the moving object is reduced to increase output signal frequency, then resolution is improved, but the signal-to-noise ratio deteriorates and crosstalk increases
Solution Approach 1:
The invention divides the detection function into multiple light-receiving devices (first and second light-receiving devices) positioned at different locations. Each device detects light independently, and their outputs are combined through logical operations to generate the final output signal. This segmentation allows the system to achieve high-frequency output signals without requiring reduced slit pitch, thereby maintaining good signal-to-noise ratio while improving resolution.
2Measurement precision
If the slit pitch is reduced to achieve higher output frequency, then resolution improves, but crosstalk between adjacent slits increases
Solution Approach 1:
The invention positions multiple light-receiving devices at different spatial locations to independently detect light from different slit regions. By segmenting the detection process across multiple devices and combining their outputs logically, the system achieves high-frequency output signals without requiring reduced slit pitch, thereby preventing crosstalk between adjacent slits.
3Measurement precision
If the output signal frequency is increased by reducing slit pitch, then resolution improves, but the device complexity increases
Solution Approach 1:
Instead of increasing frequency by reducing slit pitch (one-dimensional approach), the invention introduces a new dimension by positioning multiple light-receiving devices at different spatial locations and using logical operations to combine their outputs. This dimensional approach generates high-frequency output signals without requiring physical changes to the slit structure, thereby avoiding increased device 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
The solution enables higher frequency output signals than the movement frequency, improving resolution and accuracy of movement information while maintaining the slit pitch, and preventing waveform collapse, even at high movement frequencies.
Implementation Method 1
a light-emitting device; and a plurality of light-receiving devices which are arranged in one direction in a region that light from the light-emitting device can reach
Data Source
AI summary
The photoelectric encoder of the present invention has a light-emitting device and light-receiving devices arranged in one direction in a region that light from the light-emitting device can reach. When a moving object that alternately has a light-on portion that produces a state in which light is incident on the light-receiving device and a light-off portion that produces a state in which light is not incident on the light-receiving device passes at a prescribed movement frequency in the one direction, an output of each of the light-receiving devices takes a value corresponding to the incidence or nonincidence of light on the light-receiving device. A logical operating section carries out operation of the logical values expressed by the outputs of the light-receiving devices to form an output signal that has a frequency different from the movement frequency.