Polygon Mirror Contamination Detection via Minimum Light Intensity
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Solution Overview
Problem
Existing image forming apparatuses face challenges in accurately determining the degree of contamination of scanning optical systems, particularly due to dust and powder dust adhering to polygon mirrors, which complicates light intensity measurement and affects image quality.
Innovation Solution
An image forming apparatus that includes a light emitter, an optical sensor, a detector for minimum light intensity levels, a switcher to adjust light intensity, and a determiner to assess contamination based on detected minimum levels, simplifying the measurement process without requiring peak value detection or pulse width analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the intensity of light received by the synchronization optical sensor is measured to determine contamination degree, then the contamination can be detected, but the circuit becomes complicated requiring peak hold circuit or pulse width counting
Solution Approach 1:
The patent extracts the essential measurement information (minimum light intensity level) from the complex signal analysis approach. Instead of using peak hold circuits or pulse width counting, the invention directly measures the minimum light intensity level during polygon mirror rotation, which corresponds to the light intensity when the mirror surface is most contaminated. This extraction of the critical measurement parameter simplifies the circuit while maintaining measurement precision for contamination detection.
Solution Approach 2:
The patent inverts the conventional measurement approach by measuring the minimum light intensity level rather than the peak or average intensity. This inversion allows the use of simpler circuitry because the minimum level directly indicates contamination degree without requiring complex signal processing. The measurement is performed by detecting when the light intensity reaches its minimum during the rotation cycle, providing a direct correlation between measured value and contamination level.
2Productivity
If a polygon mirror rotates at high speed to increase productivity, then image forming speed improves, but dust and powder dust are sucked into the rotating airflow and adhere on the polygon mirror causing contamination
Solution Approach 1:
The patent implements a feedback mechanism where the light intensity level detected by the optical sensor is continuously monitored and fed back to the light emitter control. When contamination is detected (indicated by reduced minimum light intensity level), the system automatically adjusts the light emission intensity to compensate for the contamination. This feedback loop allows the system to maintain image quality despite high-speed operation that causes contamination, resolving the contradiction between productivity and contamination.
Solution Approach 2:
The patent changes the operating parameter of the light emitter by adjusting its light emission intensity based on the detected contamination level. When the polygon mirror becomes contaminated during high-speed rotation, the system increases the light emission intensity to compensate for the reduced light reflection from the contaminated mirror surface. This dynamic parameter adjustment maintains image forming quality while allowing continuous high-speed operation.
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 simplifies the circuit for light intensity measurement, allowing for effective determination of contamination levels and maintaining image quality by adjusting light intensity, thereby extending the life of optical components and reducing the need for frequent replacements.
Implementation Method 1
a photodiode provided for synchronization of main scanning... detecting a photoelectric conversion level
Data Source
AI summary
An image forming apparatus including a polygon mirror that deflects a light beam includes: a light emitter that emits the light beam; an optical sensor that is disposed at a position on which the light beam deflected by the polygon mirror is incident; a detector that detects a minimum level being a light intensity level of the light beam, the lowest within a range detected by the optical sensor; a switcher that switches a light intensity level of the light beam emitted from the light emitter until the detector detects the minimum level; and a determiner that determines a degree of contamination of a component on an optical path of the light beam extending from the light emitter to the optical sensor, on the basis of the minimum level detected when the light intensity level is switched by the switcher.