Charger Current Detection for Cartridge Attachment Judgment
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Solution Overview
Problem
In multicolor image forming apparatuses, sharing a high-voltage power supply among chargers complicates individual voltage adjustment, leading to potential high voltage failures if a process cartridge is not attached, as the current through chargers cannot be controlled effectively.
Innovation Solution
An image forming apparatus with a charge voltage application circuit, current detection units, and a controller that detects currents through each charger, allowing it to determine if a process cartridge is attached by setting thresholds for normal operation, thereby preventing excessive voltage application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a high-voltage power supply is shared among multiple chargers to reduce component number and downsize the apparatus, then device complexity is reduced, but it becomes impossible to individually adjust voltage levels to control current through each charger, leading to potential high voltage failures
Solution Approach 1:
The patent implements a feedback mechanism by detecting the current flowing through each charger and using this information to control the voltage applied by the shared power supply. The controller adjusts the voltage level based on detected current values to maintain current within a predetermined range, preventing excessive voltage application while using a shared power supply configuration.
Solution Approach 2:
The patent dynamically changes the voltage parameter applied to chargers based on detected current conditions. When a process cartridge is not attached or current is abnormal, the controller modifies the voltage level to prevent damage, thereby adapting the electrical parameters to the actual operational state of the system.
2Manufacturing precision
If voltage levels are controlled to make current through a selected charger equal to a target value, then image quality is maintained, but when the process cartridge is not attached, the current does not change even with voltage control, causing excessive voltage application
Solution Approach 1:
The patent performs preliminary detection of current flow conditions before applying full voltage levels. By detecting whether a process cartridge is properly attached and whether current flows as expected, the system prepares appropriate voltage control strategies in advance, preventing excessive voltage application before damage can occur.
Solution Approach 2:
The system continuously monitors current through each charger and uses this feedback to adjust voltage levels. When the process cartridge is not attached and current remains at zero or abnormal levels despite voltage application, the feedback mechanism triggers voltage reduction or shutdown to prevent damage.
3Volume of moving object
If the number of chargers is reduced by sharing power supply, then the apparatus is downsized, but individual current control capability is lost
Solution Approach 1:
The shared power supply is designed to perform multiple functions: it can apply voltage to multiple chargers simultaneously, detect current through each individual charger, and independently control voltage levels for each charger based on detected conditions. This multi-functionality allows individual control capability to be maintained despite the shared configuration.
Solution Approach 2:
Individual current detection for each charger enables the controller to provide independent feedback control to each charger circuit, maintaining the ability to individually adjust and control current through each charger even though they share a common power supply source.
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
Enables precise judgment of process cartridge attachment, preventing high voltage failures and ensuring stable image quality by controlling charger currents and voltage levels, reducing the risk of power supply failures.
Implementation Method 1
a current detection unit configured to detect a current flowing through each of the plurality of chargers
Data Source
AI summary
An image forming apparatus, comprising: a charge voltage application circuit configured to be connected to a plurality of chargers in a process cartridge and to apply a voltage to the plurality of chargers; a current detection unit configured to detect a current flowing through each of the plurality of chargers; and a controller. The controller judges that the process cartridge is not attached to the image forming apparatus when the current smaller than a first threshold is detected by the current detection unit in a state where the charge voltage application circuit generates a predetermined voltage.