Scanning Optical Device with f-theta and f-sin Theta Characteristics
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Solution Overview
Problem
Two-dimensional scanning optical devices face issues with curved scanning lines and uneven intervals between scanning lines, which are difficult to correct optically, leading to light intensity unevenness and increased processing loads, and the production of anamorphic optical systems is costly due to their rotationally asymmetric shape.
Innovation Solution
A scanning optical device configuration with a condensing optical system having an f-θ characteristic, a collecting optical system with an f-sin θ characteristic, and a scanning optical system also with an f-sin θ characteristic, allowing for even spacing of scanning lines without electrical corrections and reducing production costs through rotationally symmetrical components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If an f-sin θ characteristic scanning optical system is used, then scanning lines become straight, but intervals between scanning lines become narrower as they apart from the center
Solution Approach 1:
The patent applies parameter changes by combining two different optical characteristics (f-θ and f-sin θ) in separate optical systems. The first scanning optical system uses f-θ characteristic to ensure straight scanning lines, while the second scanning optical system uses f-sin θ characteristic to correct the interval narrowing. This parameter combination resolves the contradiction between straight scanning lines and uniform interval spacing.
2Manufacturing precision
If electrical correction processes are used, then scanning line interval uniformity improves, but processing load increases and frame rate must be reduced
Solution Approach 1:
The patent replaces electrical correction processes with an optical correction system. Instead of using image interpolation or driving speed control (electrical methods), the invention uses a second scanning optical system with f-sin θ characteristic that optically corrects the scanning line intervals. This substitution eliminates the need for post-processing electrical corrections, maintaining high frame rates while achieving uniform scanning line spacing.
3Manufacturing precision
If an anamorphic optical system is used, then scanning line interval uniformity improves, but production cost increases due to rotationally asymmetric shape
Solution Approach 1:
The patent segments the scanning optical system into two separate systems: a first scanning optical system with f-θ characteristic for straight scanning lines, and a second scanning optical system with f-sin θ characteristic for interval uniformity. This segmentation allows each component to be manufactured using standard rotationally symmetric designs, avoiding the need for expensive anamorphic (rotationally asymmetric) optics while achieving the same correction effect.
4Manufacturing precision
If image interpolation process is used, then scanning line interval uniformity improves, but light intensity unevenness and image degradation remain
Solution Approach 1:
The patent applies preliminary action by correcting the scanning line intervals optically before the light reaches the image plane. The second scanning optical system with f-sin θ characteristic pre-corrects the interval narrowing caused by the first system, ensuring uniform scanning line spacing is achieved at the source. This prevents light intensity unevenness and image degradation that would result from post-processing electrical corrections.
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
The solution ensures straight scanning lines with even spacing, reducing production costs and avoiding the complications of electrical corrections, while maintaining high image quality and suppressing distortions.
Implementation Method 1
a condensing optical system that generates an intermediate image of the light beam deflected by the first deflector
Implementation Method 2
a collecting optical system that collects each chief ray corresponding to each intermediate image formed by the condensing optical system
Implementation Method 3
a scanning optical system that scans the light beam deflected by the second deflector on the surface to be scanned
Data Source
AI summary
A scanning optical device includes at least one light source unit for emitting a light beam, a first deflector for deflecting the emitted light beam in an auxiliary scanning direction, a condensing optical system for generating an intermediate image of the light beam deflected by the first deflector, a collecting optical system for condensing a light beam diverged from the generated intermediate image, a second deflector for deflecting the condensed light beam in a main-scanning direction, and a scanning optical system for scanning the surface to be scanned with the light beam deflected by the second deflector. The condensing optical system has an f-θ characteristic, the collecting optical system has an f-sin θ characteristic, and the scanning optical system has an f-sin θ characteristic.