Optical Print Head Light Uniformity Correction
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Solution Overview
Problem
Existing optical writing devices using OLEDs face uneven light amounts due to changes in ambient temperature and humidity, leading to inefficiencies in light collection efficiency and complex processing for correction.
Innovation Solution
An optical print head with a detection unit that measures the linear expansion difference between the OLED panel and the rod-lens array, and a correction unit that adjusts light emission to offset these differences, ensuring accurate light amount correction across varying environmental conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lens correction values are changed based on environmental conditions, then unevenness in light amounts can be prevented, but errors in estimation of relative positions still cause unevenness
Solution Approach 1:
The patent replaces the mechanical/thermal expansion-based position change with an optical detection method. A detection OLED and light receiving element measure the actual light amount to directly detect relative position deviations, substituting physical expansion measurement with optical measurement for higher precision.
Solution Approach 2:
The patent implements a feedback mechanism where the detected light amount from the detection OLED is fed back to the correction unit, which then adjusts the drive current of exposure OLEDs in real-time to compensate for position deviations, creating a closed-loop control system.
2Adaptability or versatility
If correction data is added for multiple environmental factors, then more types of unevenness can be prevented, but processing becomes complex and storage requirements increase
Solution Approach 1:
The patent changes the approach from storing multiple correction value tables for different environmental factors to using a single detection OLED that directly measures the actual light amount. The correction unit then calculates correction values based on detected position deviations, transforming multiple parameter-based corrections into a single unified detection-and-calculate approach.
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 effectively corrects light unevenness caused by temperature and humidity changes, improving the accuracy and simplicity of light amount adjustment in optical writing devices.
Implementation Method 1
a detection unit that detects an index value of linear expansion difference
Implementation Method 2
an optical member elongated in the longitudinal direction with optical elements arranged along the longitudinal direction, the optical elements collecting light emitted by the light emitting elements
Implementation Method 3
The rod-lens array is an optical element in which a large number of rod lenses are arrayed, and light collection efficiency for light emitted from an OLED differs depending on position of the OLED relative to a rod lens
Implementation Method 4
the rod-lens array uses resin, integrating a large number of rod lenses, and has a larger linear expansion coefficient than the glass substrate on which the OLEDs are mounted. Thus, when ambient temperature varies, positions of the OLEDs on the glass substrate and the rod lenses relative to each other change
Data Source
AI summary
An optical print head including a light emitting member, an optical member, a detection unit, and a correction unit. The light emitting member is elongated in a longitudinal direction with light emitting elements arranged along the longitudinal direction. The optical member is elongated in the longitudinal direction with optical elements arranged along the longitudinal direction, the optical elements collecting light emitted by the light emitting elements. The detection unit detects an index value of linear expansion difference in the longitudinal direction of the light emitting member and the optical member. The correction unit uses the index value to correct an emitted light amount for each of the light emitting elements in order to offset differences in light collection efficiency caused by the linear expansion difference.