Encoder Protection Circuit for Internal Power Supply Overvoltage
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Solution Overview
Problem
Encoders driven by multiple power supplies face challenges in preventing overvoltage breakdowns due to power supply abnormalities, such as short-circuits, which can damage electronic components in the encoder main circuit.
Innovation Solution
The encoder incorporates an overvoltage breakdown prevention circuit that generates a driving voltage for an abnormality detection unit based on the main power supply voltage, allowing the unit to detect abnormalities in the internal power supply and shut off the encoder main circuit driving voltage when an abnormality is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the abnormality detection unit is driven directly by the main power supply voltage, then the detection function can be simplified, but the encoder main circuit may suffer overvoltage breakdown when short-circuit occurs between power supplies
Solution Approach 1:
The patent introduces an overvoltage breakdown prevention circuit as an intermediary between the main power supply voltage and the abnormality detection unit. This circuit generates an abnormality detection unit driving voltage that is safe for the detection unit while preventing overvoltage from reaching the encoder main circuit. The intermediary circuit thus protects the system without significantly increasing overall complexity.
2Reliability
If the abnormality detection unit driving voltage is generated based on main power supply voltage, then the detection unit can operate safely, but additional circuitry is required
Solution Approach 1:
The overvoltage breakdown prevention circuit serves multiple functions: it generates the abnormality detection unit driving voltage from the main power supply voltage, prevents overvoltage breakdown in the encoder main circuit, and ensures safe operation of the detection unit. By combining these functions into a single circuit, the patent minimizes the increase in device complexity while achieving comprehensive protection.
3Reliability
If power supply from monitoring-target power supply is shut off when abnormality is detected, then breakdown is prevented, but the abnormality detection circuit may be affected by short-circuit between different power supplies
Solution Approach 1:
The patent implements beforehand cushioning by generating the abnormality detection unit driving voltage through the overvoltage breakdown prevention circuit before any abnormality occurs. This ensures that even if a short-circuit happens between the main power supply and internal power supply, the detection unit is already protected from overvoltage and can safely detect abnormalities without being damaged by the short-circuit condition.
Data Source
AI summary
This encoder comprises: an encoder main circuit that is driven using an encoder main circuit driving voltage supplied from at least one internal power source to generate rotation information of a rotating element; an overvoltage breakdown prevention circuit that generates an abnormality detection unit driving voltage on the basis of a voltage supplied from a main power source; an abnormality detection unit that is driven using the abnormality detection unit driving voltage outputted from the overvoltage breakdown prevention circuit to detect an abnormality related to the internal power source; and a cut-off circuit that cuts off supply of the encoder main circuit driving voltage from the internal power source to the encoder main circuit upon detection by the abnormality detection unit of an abnormality.