Energization Control Device Zero-Cross Timing Correction
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Solution Overview
Problem
Existing energization control devices for image forming apparatuses face challenges in reducing switching noise due to temporal deviations in zero-cross point detection, leading to increased costs and complexity, particularly when using alternating current power sources.
Innovation Solution
An energization control device with a voltage detection unit that outputs detection signals based on voltage thresholds and a control portion that calculates correction values to adjust switching timing, allowing for precise zero-cross point alignment without full-wave rectification or voltage detection circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a zero-cross detection circuit with threshold voltage is used to control triac switching, then the circuit can detect voltage crossings, but the detected timing deviates from the true zero-cross point causing switching noise
Solution Approach 1:
The invention uses feedback by detecting both edges of the pulse signal, calculating the actual half-period, comparing it with the ideal half-period, and generating a correction value that is applied to adjust the triac switching timing. This closed-loop feedback mechanism eliminates the threshold-induced timing deviation and reduces switching noise.
Solution Approach 2:
The invention changes the parameter used for zero-cross detection from a fixed threshold voltage method to a dynamic method based on measured pulse signal characteristics. By calculating the correction value from the actual half-period and applying it to adjust the switching timing, the system adapts to eliminate timing errors caused by threshold voltage.
2Object-generated harmful factors
If filter capacity is increased to suppress switching noise emission, then noise emission is reduced, but the filter size increases making downsizing difficult
Solution Approach 1:
The invention converts the harmful effect of threshold voltage deviation into a beneficial correction mechanism. By detecting the timing deviation caused by the threshold and calculating a correction value, the system transforms the source of switching noise into the basis for eliminating it, allowing noise reduction without increasing filter size.
Solution Approach 2:
The invention replaces the passive mechanical/electrical filtering approach with an active control approach. Instead of relying on larger filter capacity to suppress switching noise, the system uses electronic timing correction to prevent the generation of switching noise in the first place, substituting a control-based solution for a filtering-based solution.
3Measurement precision
If full-wave rectification and voltage detection circuits are added to accurately detect zero-cross point, then timing accuracy improves, but circuit complexity and cost increase
Solution Approach 1:
The invention makes the existing zero-cross detection circuit serve dual purposes: it not only detects voltage crossings but also provides the information needed to calculate timing correction. By utilizing the pulse signal edges and half-period measurement from the existing circuit, the system achieves accurate timing without requiring additional full-wave rectification or voltage detection circuits.
Solution Approach 2:
The invention makes the zero-cross detection circuit multi-functional by using it both for detecting voltage crossings and for measuring the actual half-period to calculate timing correction. This universal use of the existing circuit eliminates the need for separate full-wave rectification and voltage detection circuits, reducing overall system complexity.
Data Source
AI summary
An energization control device includes a voltage detection unit, a control portion, and an energization switching unit. The control portion to which the first detection signal and the second detection signal are input from the voltage detection unit is configured to output a first energization signal if the first detection signal is input and output a second energization signal if the second detection signal is input. The control portion is configured to obtain a correction value based on a difference between a first period in which the first detection signal is input to the control portion and a second period in which the second detection signal is input to the control portion and to correct a timing of switching between the first energization signal and the second energization signal with the correction value.