Linear Light Position Detection with Foreign Substance Compensation
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Solution Overview
Problem
Image forming apparatuses face challenges in accurately identifying the position of a recording medium in a conveyance path due to foreign substances adhering to light emission and reception portions, which affects the accuracy of shading correction and position identification.
Innovation Solution
Incorporating a data processing device with binarization, light emission control, and characteristic data storage to derive a set light amount for linear light emission, allowing for accurate position identification and image formation by generating binarization data and adjusting light levels based on threshold and incident light levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light source and light reception portions are provided in the conveyance path to detect the recording medium position, then the position identification capability is improved, but foreign substances adhering to the light emission and reception portions cause measurement errors that deteriorate the accuracy
Solution Approach 1:
The system performs preliminary measurement when no recording medium is conveyed to detect foreign substances on the light emission and reception portions. This advance detection allows the system to identify and compensate for measurement errors caused by foreign substances before actual position measurement begins, thereby maintaining high measurement precision despite the presence of contaminants.
Solution Approach 2:
The system continuously monitors the light reception levels and compares them against reference values obtained during preliminary measurement. When deviations are detected that indicate foreign substance adhesion, the system automatically adjusts the light emission amount or applies correction factors to the position calculation, forming a closed-loop feedback mechanism that maintains accuracy despite deteriorating conditions.
2Measurement precision
If the light emission amount is increased to improve signal strength for position detection, then the detection capability is improved, but foreign substances cause excessive light blocking that worsens measurement accuracy
Solution Approach 1:
The system dynamically adjusts the light emission amount based on the presence and severity of foreign substance adhesion. During preliminary measurement, when foreign substances are detected, the system modifies the light emission parameters (intensity, duration) to compensate for the blocking effect, ensuring sufficient signal strength reaches the light reception portions for accurate position detection despite the obstruction.
3Manufacturing precision
If shading correction is performed using data from light reception portions, then image quality is improved, but foreign substances cause incorrect correction that deteriorates image quality
Solution Approach 1:
The system performs shading correction using reference measurements taken when no recording medium is conveyed, establishing a baseline correction profile. This preliminary correction data accounts for the light blocking characteristics of foreign substances on the light emission and reception portions. During actual image formation, this pre-established correction profile is applied to compensate for foreign substance effects, ensuring accurate shading correction and maintaining high image quality.
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
Ensures accurate identification and correction of the recording medium's position, even with foreign substances present, by deriving a set light amount that maintains data integrity and image quality.
Implementation Method 1
The light source emits linear light extending in a main scanning direction toward the recording medium that is being conveyed in the conveyance path. The plurality of light reception portions face the light source across the conveyance path, and receive the linear light that has transmitted through the recording medium.
Data Source
AI summary
A data acquiring portion acquires a plurality of pieces of second data having different levels depending on amounts of light incident on the light reception portions upon reception of a specific linear light having a specific amount of light. A level acquiring portion acquires a maximum level and a minimum level from among the levels of the plurality of pieces of second data. A characteristic data storage portion preliminarily stores characteristic data that indicates levels of the plurality of pieces of second data. A light amount deriving portion executes a light amount deriving process to derive a set light amount of the linear light based on a threshold, the maximum level, the minimum level, and the characteristic data. A second light emission control portion causes the light emission portion to emit linear light having the set light amount.