Optical Print Head Voltage Drop Compensation
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Solution Overview
Problem
Existing optical print heads face issues with uneven light emission due to potential drops on power lines, leading to image unevenness and reduced light emission duty ratios, which are not adequately addressed by current configurations with auxiliary power lines or methods that turn off light-emitting elements.
Innovation Solution
The optical print head employs a configuration with current-driven light-emitting elements, first and second power lines, first and second holding elements, and a control unit that performs specific holding operations to manage voltage differences and drive current supply, ensuring uniform light emission by disconnecting and reconnecting holding elements to maintain reference voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If auxiliary power lines are provided to reduce potential drop, then light emission uniformity is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent segments the power supply function by providing multiple power feeding points along the power line. Instead of using complex auxiliary power lines, the single power line is divided into multiple segments by introducing intermediate feeding points that supply power at different locations, thereby reducing potential drop across different regions of the light-emitting element array.
Solution Approach 2:
The patent introduces auxiliary power feeding points as intermediary elements along the power line. These feeding points act as mediators that inject additional power into the system at strategic locations, reducing the potential drop between the main power feeding point and distant light-emitting elements without requiring complex auxiliary wiring configurations.
2Manufacturing precision
If light-emitting elements are turned off during single line writing to prevent potential drop, then light emission uniformity is improved, but light emission duty ratio decreases
Solution Approach 1:
The patent applies preliminary action by providing power feeding points in advance at optimized locations along the power line. This preliminary power distribution arrangement ensures that potential drop is minimized before light emission occurs, eliminating the need to turn off light-emitting elements during operation. The power infrastructure is prepared beforehand to handle the full light emission duty ratio without causing uniformity issues.
3Manufacturing precision
If power line length is reduced to minimize potential drop, then light emission uniformity is improved, but device area increases
Solution Approach 1:
The patent applies local quality by providing power feeding points at different locations along the power line according to the specific power distribution needs of different regions. Instead of uniformly shortening the entire power line, intermediate feeding points are strategically placed to address local potential drop issues in specific areas, maintaining overall device compactness while improving light emission uniformity locally.
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 configuration effectively suppresses unevenness in light emission and increases the light emission duty ratio by maintaining uniform reference voltages and reducing potential drops, thereby enhancing the operational efficiency of the print head.
Implementation Method 1
a plurality of light-emitting elements (organic EL elements) arranged in a line shape in a main scanning direction
Data Source
AI summary
An optical print head includes: light-emitting elements in line shape; first power line supplying first reference voltage; second power line supplying drive current to each light-emitting element and supplying second reference voltage; DAC outputting first voltage indicating light emission amount of each light-emitting element; first elements for holding first voltage difference between the first reference voltage and the first voltage; second elements each electrically connectable with corresponding first element and for holding second voltage difference between the second reference voltage and second voltage according to the first voltage, and during supply of drive current, controls each first element to hold the first difference by electrically disconnecting the first and second elements, and temporarily suspends supply of the drive current, and controls the second element to hold the second difference by electrically connecting the first and second elements, such that the drive current according to the second voltage difference is supplied.