Voltage Detection Apparatus with Correction for Isolation Drift
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Solution Overview
Problem
Conventional voltage detection apparatuses for AC power supplies face challenges in accurately detecting voltage under varying conditions due to changes in temperature and aging, leading to deviations in detected power supply voltage, which can result in degraded image quality in image forming devices.
Innovation Solution
A voltage detection apparatus with a transmission unit, control unit, reference power supply, voltage conversion unit, and switching unit that corrects voltage values by switching between reference and converted voltages to account for variations caused by temperature and aging, ensuring accurate detection of AC power supply voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional voltage detection apparatuses use a transmission unit with primary and secondary sides insulated from each other to transmit voltage information, then safety and isolation are improved, but measurement precision deteriorates due to changes in transmission rate (CTR) caused by temperature and aging conditions
Solution Approach 1:
The patent applies parameter changes by introducing a correction value that compensates for variations in transmission rate (CTR) caused by temperature and aging. The control unit calculates a correction value based on the ratio between an expected A/D conversion value (obtained when a reference voltage is applied) and an actual A/D conversion value, then uses this correction value to adjust the detected voltage information, thereby maintaining measurement precision despite changes in transmission characteristics.
Solution Approach 2:
The patent implements feedback by using the actual A/D conversion value obtained from the transmission unit to calculate a correction value, which is then applied to subsequent voltage measurements. This feedback mechanism continuously compensates for drift in transmission rate, ensuring accurate voltage detection over time and under varying environmental conditions.
2Ease of operation
If a photocoupler is used to generate a zero-crossing signal from AC voltage, then voltage detection is enabled, but measurement precision deteriorates due to sag or noise in the AC voltage causing pulse shifts in the zero-crossing signal
Solution Approach 1:
The patent addresses this issue by introducing a correction value that compensates for errors introduced by sag or noise in the AC voltage. The correction mechanism adjusts the detected voltage based on the ratio between expected and actual A/D conversion values, thereby correcting shifts in zero-crossing signal pulses and maintaining accurate power supply voltage detection.
3Adaptability or versatility
If the transmission rate (CTR) changes due to temperature and aging conditions, then device adaptability to environmental conditions is improved, but measurement precision deteriorates as the voltage converted on the secondary side significantly changes
Solution Approach 1:
The patent directly addresses this contradiction by calculating a correction value that compensates for CTR changes due to temperature and aging. The control unit obtains a correction value based on the ratio between expected and actual A/D conversion values when reference voltage information is input, then applies this correction to maintain accurate voltage detection despite environmental variations.
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 precise detection of AC power supply voltage, independent of temperature and aging effects, thereby maintaining consistent power supply to image forming devices and preventing image quality degradation.
Implementation Method 1
a transmission unit whose primary and secondary sides are insulated from each other, the transmission unit configured to transmit information according to a value of an AC voltage from the primary side to the secondary side
Implementation Method 2
a voltage conversion unit configured to convert the detected information into a converted voltage
Data Source
AI summary
The voltage detection apparatus includes a reference power supply that outputs a predetermined voltage; a voltage conversion unit that converts detected information into a voltage; and a switching unit that switches between a first state in which the predetermined voltage is supplied from the reference power supply to the primary side of a transmission unit, and a second state in which the voltage resulting from the conversion is supplied from the voltage conversion unit to the primary side of the transmission unit. The switching unit switches to the first state, in which a correction value for correcting a digital value is acquired. The switching unit switches to the second state, in which a voltage value acquired based on the digital value is corrected with the correction value to acquire a corrected voltage value.