Print Head Temperature Compensation for Image Density Uniformity
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Solution Overview
Problem
In image forming apparatuses, such as printers, the variation in light emission amounts among light emitting elements in print heads due to temperature differences leads to fluctuations in image density, affecting print quality.
Innovation Solution
A print head design incorporating a mounting board with a light source portion, a drive member, and temperature detectors, where the drive member generates a lighting signal based on temperatures detected by both first and second temperature detectors, and an optical unit forms an image of the light emitted, allowing for correction of light emission periods to stabilize emission amounts across light emitting elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single temperature detector is used near the drive member, then the structure is simple, but the temperature distribution across the light emitting elements cannot be accurately measured leading to image density fluctuations
Solution Approach 1:
The temperature detection function is segmented into multiple detectors positioned at different locations (first temperature detector near drive member, second temperature detector at farther position). This segmentation allows independent measurement of temperature variations across different zones of the mounting board, enabling accurate compensation for each light emitting element's temperature without requiring a single complex detector
Solution Approach 2:
Multiple temperature detectors act as intermediaries between the heat sources (drive member and light emitting elements) and the control system. By placing detectors at strategic positions, they mediate the temperature information from different zones, allowing the control unit to calculate and compensate for temperature-induced variations in light emission amounts
2Stability of the object's composition
If temperature compensation is implemented for all light emitting elements, then image density uniformity improves, but the control system complexity increases
Solution Approach 1:
The patent applies local quality by providing temperature compensation tailored to each light emitting element's specific location and temperature conditions. The control unit calculates individual correction values based on temperatures detected by nearby detectors, allowing each element to be compensated according to its local thermal environment rather than applying a uniform correction to all elements
Solution Approach 2:
The control system dynamically changes the lighting signal parameters (light emission duration, intensity) based on detected temperature variations. By adjusting these parameters in response to temperature measurements, the system compensates for temperature-induced emission variations, maintaining uniform image density across all light emitting elements
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 stabilizes light emission amounts, reducing variations in image density and improving print quality by accurately adjusting the lighting periods based on temperature measurements, ensuring consistent output across the print head.
Implementation Method 1
a light source portion (63) that includes plural light emitting elements (L1-Ln)
Implementation Method 2
light emitting elements provided on one surface of the mounting board
Implementation Method 3
a first temperature detector that is provided on the mounting board, and at least one second temperature detector that is provided at a farther position on the mounting board from the drive member than the first temperature detector
Data Source
AI summary
A print head includes: a mounting board; a light source portion that includes a plurality of light emitting elements provided on one surface of the mounting board; a drive member that is provided on other surface of the mounting board so as to generate a lighting signal and drive the light source portion; and a first temperature detector that is provided on the mounting board, and at least one second temperature detector that is provided at a farther position on the mounting board from the drive member than the first temperature detector; and the drive member includes: a light emitting unit that generates the lighting signal based on a temperature detected by the first temperature detector and a temperature detected by the second temperature detector; and an optical unit that forms an image of light emitted from the light emitting unit.