Toner Density Correction via Light Intensity Control
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Solution Overview
Problem
Existing image forming apparatuses using reflection type optical sensors face challenges in accurately measuring toner density due to dispersion in the installation position and angle of light emitters and photodetectors, leading to inconsistencies in photodetection intensity and calculated toner density.
Innovation Solution
An image forming apparatus with a sensor light intensity control unit and a density determining unit that adjusts light intensity and determines a correction parameter to correct toner density measurements by controlling the light emitter's voltage, thereby compensating for dispersion-related errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reflection type optical sensor is used to measure toner density, then the measurement can exclude influence of dirt on the light emitter and LED intensity fluctuation, but dispersion in installation position and angle of the sensor components causes inconsistency in photodetection intensity and reduces measurement precision
Solution Approach 1:
The patent changes the parameter of light intensity by introducing a control voltage to the light emitter. The density determining unit varies the light emitter's output intensity and determines a correction parameter (first-order coefficient) representing the relationship between control voltage and photodetector output. This correction parameter is then used to correct toner density measurements, compensating for dispersion effects while maintaining the reliability benefits of the reflection type sensor.
2Ease of manufacture
If separate installation of focusing lenses is performed for chip-shaped LED and PD, then the sensor structure becomes more flexible and easier to manufacture, but dispersion occurs on chip position and angle leading to photodetection intensity variation
Solution Approach 1:
The patent implements a feedback mechanism where the density determining unit determines a correction parameter based on the actual photodetection output at varying light intensities. This correction parameter (first-order coefficient) represents the system's actual response characteristics including any dispersion effects from separate component installation. The correction parameter is then fed back to correct subsequent measurements, allowing the system to compensate for manufacturing tolerances while maintaining ease of assembly.
3Illumination intensity
If light intensity of the light emitter is increased to improve signal strength, then photodetection intensity increases, but dispersion in chip position causes non-linear response and measurement error
Solution Approach 1:
The patent introduces dynamics by varying the light emitter's output intensity through control voltage adjustment. Instead of using fixed light intensity, the system dynamically changes the light intensity and measures the corresponding photodetector output at multiple intensity levels. This dynamic approach allows determination of a correction parameter that captures the system's actual response characteristics, enabling accurate toner density measurement even with component dispersion.
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
The solution ensures precise toner density measurement by correcting for dispersion-related errors, maintaining accuracy even under conditions of relative position and angle dispersion between the sensor and image carrier, thus improving the reliability of toner density calculations.
Implementation Method 1
a measurement method of a toner density on an image carrier using a reflection type optical sensor calculates an index (e.g. coverage factor mentioned below or the like) that indicates a toner density on the basis of a change of an output voltage of the reflection type optical sensor
Data Source
AI summary
A sensor includes a light emitter and a photodetector. The light emitter outputs light with which a toner pattern or a surface material of an image carrier is irradiated. The photodetector receives reflection light from the toner pattern or the surface material. The sensor light intensity control unit provides a control voltage to the light emitter and thereby controls light intensity of the light emitter. The density determining unit determines a toner density on the basis of output of the photodetector. Further, the density determining unit (a) determines as a correction parameter a first-order coefficient of the control voltage of the light emitter for an output voltage of the photodetector corresponding to reflection light from the surface material, (b) determines a correction amount corresponding to the correction parameter and the toner density, and (c) corrects the toner density on the basis of the correction amount.