High Voltage Power Supply Offset Voltage Delay Circuit
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Solution Overview
Problem
Conventional high voltage power supplies in laser printers generate abnormally high voltages when turned on, leading to deteriorated image quality and unstable printing operations due to premature application of offset voltage to the photoconductive drum.
Innovation Solution
A high voltage power supply with a feedback unit incorporating an offset voltage signal delay circuit, utilizing a resistor-capacitor (RC) circuit to control the timing of offset voltage application, preventing abnormally high voltage generation by comparing and adjusting the voltage levels through a switching drive control unit and fly-back transformer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If offset voltage is supplied to the output signal to enable feedback control, then the voltage regulation performance is improved, but abnormally high voltage is generated during power-on causing image quality deterioration
Solution Approach 1:
The patent applies preliminary action by introducing a delay circuit that prevents the offset voltage from being supplied during the initial power-on phase. The delay circuit ensures that the offset voltage is only applied after a predetermined time has elapsed, allowing the system to stabilize first. This resolves the contradiction by enabling voltage regulation precision through offset voltage while preventing abnormally high voltage damage during power-on by delaying the offset voltage application until the system is ready.
2Productivity
If offset voltage is immediately applied after power-on, then voltage feedback control can start earlier, but printing operation stability deteriorates due to abnormal voltage
Solution Approach 1:
The delay circuit performs preliminary action by blocking the offset voltage during the critical power-on stabilization period and then enabling it afterward. This ensures that voltage feedback control starts at the appropriate time when the system is stable, maintaining printing operation reliability while still achieving timely voltage control response.
Solution Approach 2:
The delay circuit acts as an intermediary between the offset voltage source and the feedback control system. It mediates the timing of offset voltage application, allowing the system to balance between quick voltage control response and stable printing operation by controlling when the offset voltage is introduced into the feedback loop.
3Use of energy by moving object
If the high voltage output unit operates immediately upon receiving PWM signal, then power conversion efficiency is improved, but image quality deteriorates due to premature high voltage application
Solution Approach 1:
The delay circuit performs preliminary action by preventing the high voltage output unit from operating during the initial power-on phase. By blocking the offset voltage that drives the feedback control, the system ensures that high voltage is not applied to the photoconductive drum until the system is fully stabilized. This resolves the contradiction by maintaining power conversion efficiency through immediate PWM response while protecting image quality by delaying actual high voltage application.
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
Prevents the generation and application of abnormally high voltages to the photoconductive drum during power-on, thereby maintaining image quality and stabilizing the printing process.
Implementation Method 1
A high voltage power supply with a feedback unit incorporating an offset voltage signal delay circuit, utilizing a resistor-capacitor (RC) circuit to control the timing of offset voltage application
Data Source
AI summary
A high voltage power supply for use in a laser printer, multifunction peripheral, or similar device, wherein the high voltage power supply includes a pulse width modulation (PWM) input unit, a high voltage output unit, and a delaying feedback unit for preventing the generation of an abnormally high voltage in an output signal of the high voltage output unit. By delaying the time when an offset voltage is supplied to the output signal, the generation of an abnormally high voltage that is applied to a surface of a photoconductive drum when a printer is turned on and which can deteriorate the quality of printed images can be prevented.