Optical Scanning Apparatus Independent Spot Size and Spacing Control
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Solution Overview
Problem
Multi-beam laser scanning units in laser printers face challenges in simultaneously achieving desired illumination spot size and spacing due to limitations in focal plane separation and optical aberration correction, particularly when using a tilted linear pattern of illumination spots.
Innovation Solution
The use of an optical emitter array with dedicated microlenses and a variable collimator allows for independent control of illumination spot size and spacing, decoupling these determinations to overcome the limitations of axial imaging systems and achieve both target spot size and spacing without substantial loss in optical efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a tilted linear pattern of illumination spots is used to control spot size and spacing independently, then spot size control is improved, but focal plane separation and optical aberration worsen
Solution Approach 1:
The patent transitions from a tilted linear pattern (2D arrangement with tilt angle) to a two-dimensional array of illumination spots. This dimensional change allows independent control of spot spacing in both horizontal and vertical directions without requiring tilt angles that cause focal plane separation. The 2D array configuration enables each spot to be precisely positioned on a single focal plane while maintaining desired spacing.
Solution Approach 2:
The patent changes the geometric parameters of the illumination spot pattern from a one-dimensional tilted line to a two-dimensional grid array. By defining spot positions using two independent spacing parameters (horizontal and vertical) rather than a single tilt angle, the system achieves precise control of spot spacing without introducing focal plane separation and optical aberration issues.
2Productivity
If multiple optical beams are used to increase printing speed, then productivity is improved, but control of illumination spot size and spacing becomes more difficult
Solution Approach 1:
The patent divides the single optical beam system into multiple independent optical beams arranged in a 2D array. Each beam is independently controllable and positioned, allowing parallel processing of multiple scan lines simultaneously. This segmentation enables increased printing speed while maintaining precise control over each individual spot's size and spacing through the array configuration.
Solution Approach 2:
The 2D array of optical beams serves multiple functions simultaneously: it increases the number of scan lines for faster printing, maintains precise spot spacing through the array geometry, and keeps all spots on a single focal plane. This multi-functional approach resolves the contradiction between productivity improvement and precision maintenance.
3Manufacturing precision
If tilt angle is adjusted to control scan line spacing, then spot spacing control is improved, but optical aberration correction becomes more difficult
Solution Approach 1:
Instead of using tilt angle to control spot spacing (which introduces optical aberration), the patent inverts the approach by using a fixed, non-tilted 2D array configuration where spacing is controlled directly by the array geometry. This eliminates the need for tilt-based spacing control and the associated optical aberration correction complexity.
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 approach enables a higher number of optical beams to be used without adverse effects from focal surface separation and optical aberrations, providing real-time control over scan line spacing and maintaining high optical efficiency.
Implementation Method 1
each optical beam is individually focused to a corresponding spot on the scanning surface
Implementation Method 2
adjusting a spacing between the array of optical emitters and a collimator of the optical system
Data Source
AI summary
An optical scanning apparatus includes: an array of optical emitters to provide a plurality of optical beams; a plurality of corresponding microlenses to receive the optical beams; and a variable collimator to receive the plurality of optical beams from the microlenses. The microlenses and variable collimator are arranged to decouple the illumination spot size of the optical beams from the illumination spot separation of the optical beams such that the illumination spot size and the illumination spot separation at a scanning surface are independently controllable.