Printing Apparatus APC Feedback Delay Reduction
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Solution Overview
Problem
The existing feedback systems in printing apparatuses with Auto Power Control (APC) functions experience delays due to current-current converters, which affect the precision and stability of maintaining a suitable light-emitting amount for forming images.
Innovation Solution
A printing apparatus is designed with a current generation unit, a comparison unit, and a conversion unit that generates a reference current with a set ratio, allowing for direct comparison and feedback control to adjust the light-emitting element's driving force, thereby reducing delays and stabilizing the light-emitting amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current-current converter is arranged in the feedback path to convert monitor current, then the feedback system can compare currents, but a delay is caused in the feedback system
Solution Approach 1:
The patent extracts the current-current converter from the feedback path and replaces it with a current generator that produces a reference current proportional to the monitor current. This removes the converting operation from the feedback loop, eliminating the delay while preserving the ability to compare currents through the operational amplifier.
Solution Approach 2:
The patent introduces an operational amplifier as an intermediary element that directly compares the monitor current with a reference current generated proportionally, without requiring current-current conversion. The operational amplifier serves as a mediator that enables precise current comparison without the delay inherent in converter circuits.
2Device complexity
If the light-emitting element is driven with fixed driving force, then the circuit is simple, but the light-emitting amount cannot be maintained at target value under varying conditions
Solution Approach 1:
The patent implements a feedback mechanism where the monitor current (proportional to light-emitting amount) is compared with a reference current, and the operational amplifier adjusts the driving signal to the light-emitting element based on this comparison. This closed-loop feedback maintains the light-emitting amount at the target value despite varying conditions.
Solution Approach 2:
The patent dynamically adjusts the driving parameters of the light-emitting element based on the feedback from the monitor current comparison. The operational amplifier modifies the driving force in real-time, changing electrical parameters to maintain optimal light emission under varying operational conditions.
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 configuration reduces feedback delays and stabilizes the light-emitting amount, enhancing the precision and efficiency of the APC system by directly adjusting the driving force based on real-time comparisons, preventing oscillations and improving image formation.
Implementation Method 1
a light-receiving element which receives light from the light-emitting element
Data Source
AI summary
A printing apparatus comprising a light-emitting element, a light-receiving element configured to output a monitor current based on a light-emitting amount from the light-emitting element, a comparison unit connected to the light-receiving element and configured to compare the monitor current with a reference current, a driving unit configured to drive the light-emitting element based on the comparison result, a current generation unit configured to generate a first current, and a conversion unit arranged in a path between the current generation unit and the comparison unit, the conversion unit outputting, upon receiving a control signal, the reference current based on the control signal and the first current.