Image Transfer Power Supply Control for Density Uniformity
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Solution Overview
Problem
Conventional image forming technologies face challenges in transferring toner evenly onto recording sheets with irregularities, leading to density unevenness and potential power supply malfunctions when switching between direct-current and alternating-current voltages for image transfer.
Innovation Solution
An image forming apparatus with a power supply unit capable of outputting both direct-current and alternating-current voltages, and a power supply control unit that manages the switching between these voltages, ensuring a longer delay when switching from alternating-current to direct-current voltage to prevent power supply malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If alternating-current voltage is used for image transfer on irregular recording sheets, then density unevenness is reduced, but power supply malfunction risk increases due to longer fall time
Solution Approach 1:
The power supply control unit performs preliminary action by setting a delayed timing for switching from alternating-current voltage to direct-current voltage. Specifically, the unit switches to direct-current voltage at a timing that is delayed by a predetermined period after the alternating-current voltage is turned off, ensuring that the voltage transition does not cause power supply malfunction while maintaining effective image transfer.
Solution Approach 2:
The invention applies dynamics by making the voltage switching timing adaptive rather than fixed. The power supply control unit dynamically adjusts the switching timing based on the type of voltage being applied, implementing different switching strategies for alternating-current to direct-current transitions versus direct-current to alternating-current transitions, thereby optimizing both image quality and power supply reliability.
2Reliability
If direct-current voltage is used for image transfer, then power supply stability is maintained, but density unevenness occurs on recording sheets with irregularities
Solution Approach 1:
The invention applies periodic action by using alternating-current voltage for image transfer. The alternating-current voltage is applied periodically to the transfer roller, creating repeated voltage cycles that help toner particles move into recesses of irregular recording sheets, thereby improving density uniformity while the controlled switching mechanism prevents power supply malfunction.
3Productivity
If voltage switching timing is optimized for fast response, then productivity is improved, but power supply malfunction risk increases
Solution Approach 1:
The power supply control unit performs preliminary action by pre-setting the delayed timing for voltage switching. The control unit is configured to switch from alternating-current voltage to direct-current voltage at a timing that is automatically delayed by a predetermined period, ensuring reliable power supply transition without requiring real-time adjustment or compromising productivity.
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
This solution effectively reduces density unevenness in images on irregular surfaces and prevents power supply malfunctions by controlling voltage switching, ensuring stable operation.
Implementation Method 1
a power supply unit configured to output one of an alternating-current-based voltage including at least an alternating-current voltage and a direct-current voltage to the transfer unit
Implementation Method 2
an alternating-current-based voltage including at least an alternating-current voltage
Implementation Method 3
a power supply control unit configured to cause the power supply unit to start switching to the alternating-current-based voltage a first time after the power supply unit stops outputting the direct-current voltage
Data Source
AI summary
An image forming apparatus includes a transfer unit configured to transfer a toner image onto a recording medium; a power supply unit configured to output one of an alternating-current-based voltage including at least an alternating-current voltage and a direct-current voltage to the transfer unit; and a power supply control unit configured to cause the power supply unit to start switching to the alternating-current-based voltage a first time after the power supply unit stops outputting the direct-current voltage in the case that output of the power supply unit is switched to the alternating-current-based voltage, and cause the power supply unit to start switching to the direct-current voltage a second time after the power supply unit stops outputting the alternating-current-based voltage in the case that output of the power supply unit is switched to the direct-current voltage. The second time is longer than the first time.