Optical Writing Device Gain Switching for Detection Accuracy
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Solution Overview
Problem
Optical writing devices with light-emitting-point arrays face challenges in achieving high detection accuracy due to varying light quantities from different light-emitting points, leading to inconsistent dynamic ranges and reduced accuracy for lower light levels.
Innovation Solution
Incorporating a gain switch unit and control unit to amplify photodetection signals from a photodetector, with gains preset based on the distance and transmittance of light-emitting points, ensuring photodetection signals coincide with a predetermined reference value, thereby enhancing detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If light quantities from different light-emitting points are detected by a single photodetector, then device complexity is reduced, but detection precision deteriorates due to varying dynamic ranges
Solution Approach 1:
The patent applies local quality by assigning different gain values to different light-emitting points based on their individual characteristics (distance from photodetector, transmittance). The gain switch unit selectively amplifies signals from each light-emitting point with a predetermined gain value, ensuring that each point's light quantity is detected with optimal sensitivity despite variations in emitted light intensity.
2Measurement precision
If gain switch unit with preset gains is introduced, then detection precision is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing gain values for each light-emitting point before actual measurement. The gain values are determined based on predetermined parameters (distance, transmittance) and stored in advance. During operation, the gain switch unit simply retrieves and applies the appropriate pre-calculated gain value, avoiding complex real-time calculations while maintaining high detection precision.
3Measurement precision
If light-quantity adjustment is performed pixel-by-pixel, then detection precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent applies self-service by implementing automatic gain switching based on the detected light-emitting point. The control unit automatically selects and applies the appropriate gain value from stored values based on which light-emitting point is currently being detected, eliminating the need for manual pixel-by-pixel adjustment. The system performs light-quantity adjustment autonomously while maintaining high detection precision.
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 improves the detection accuracy and dynamic range for optical writing devices, ensuring consistent light-quantity adjustment across different light-emitting points, leading to higher precision in image forming applications.
Implementation Method 1
a photodetector for detecting the quantities of light emitted from a plurality of light-emitting points
Implementation Method 2
a gain switch unit for outputting photodetection signals obtained by amplifying the signals output from the photodetector
Data Source
AI summary
An optical writing device having; a plurality of light-emitting points; a plurality of drive circuits for supplying drive currents to the plurality of light-emitting points respectively; a photodetector for outputting signals indicating quantities of light entering thereto from the respective light-emitting points; a gain switch circuit for outputting photodetection signals obtained by amplifying the signals output from the photodetector in regard to the respective light-emitting points with gains preset for the respective light-emitting points; and a control circuit for controlling the drive circuits such that the photodetection signals output from the gain switch circuit in regard to the respective light-emitting points coincide with a value substantially equal to a predetermined reference value. The gains for the respective light-emitting points are preset based on the distances between the photodetector and the respective light-emitting points.