Light Scanning Unit Synchronization Detection
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Solution Overview
Problem
Conventional light scanning units require large f-θ lenses or polygon mirrors to accommodate varying rotational directions of the polygon mirror, leading to increased complexity and size, especially when using cross-scanning methods.
Innovation Solution
A light scanning unit with a synchronization detection optical system arranged to satisfy a specific angle relationship (0.9≦B/A≦1.1) between the polygon mirror's spacing angle and the deflection angle, using a synchronization detection optical system that includes a lens and sensor, and optionally a reflection mirror, to detect light divided and reflected at the polygon mirror's edge, without requiring the light to pass through the image forming optical system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the rotational direction of the polygon mirror varies or cross-scanning method is used, then the synchronization detection capability is improved, but the size of f-θ lens or polygon mirror must be increased
Solution Approach 1:
The light beam is divided into multiple beams by the edge of the polygon mirror, with one beam directed to the synchronization detection optical system and another beam directed to the image forming optical system. This segmentation allows simultaneous synchronization detection and image formation without requiring enlarged optical components.
Solution Approach 2:
The polygon mirror edge serves multiple functions: it acts as both the scanning surface for image formation and the beam dividing element for synchronization detection. The synchronization detection optical system uses the same polygon mirror structure to obtain synchronization signals, eliminating the need for separate detection components or enlarged optics.
2Measurement precision
If conventional synchronization detection systems are used with varying rotational directions, then detection accuracy is maintained, but device complexity increases
Solution Approach 1:
The synchronization detection optical system is integrated with the existing image forming optical system, sharing common components such as the polygon mirror and light source. The synchronization detection sensor receives a portion of the light beam that is divided by the polygon mirror edge, combining both functions in a single optical path without requiring separate detection systems.
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 allows for compact and efficient synchronization detection, reducing the need for large f-θ lenses or polygon mirrors, and enables accurate detection of synchronization signals regardless of the polygon mirror's rotational direction, thus optimizing the optical configuration for image forming apparatuses.
Implementation Method 1
a polygon mirror deflecting and scanning light emitted from the light source unit, in a main scanning direction
Implementation Method 2
an image forming optical system condensing the deflected light
Implementation Method 3
a synchronization detection optical system detecting a portion of light that is divided and reflected at an edge of the polygon mirror
Data Source
AI summary
A light scanning unit includes: a light source unit; a polygon mirror for deflecting and scanning light emitted from the light source unit, in a main scanning direction, and having a plurality of deflection surfaces and a plurality of edges at which adjacent deflection surfaces meet one another; an image forming optical system for condensing the deflected light; and a synchronization detection optical system for detecting a portion of light that is divided and reflected at an edge of the polygon mirror. The light scanning unit may be incorporated into an image forming apparatus.