BD Sensor Placement for Compact Light Scanning Devices
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Solution Overview
Problem
The existing light scanning devices face challenges in downsizing and thinning due to the placement of the BD sensor, which either requires increasing the device's width and depth to accommodate the sensor outside the scanning angle range or causes interference when placed within the scanning angle range.
Innovation Solution
The light scanning device is configured with an optical sensor positioned inside the scanning angle range of the light beam, farther from the deflecting section than the last reflective mirror, allowing for a compact design without interfering with the light beam, and optionally using a detecting mirror to improve detection accuracy and mounting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the BD sensor is disposed outside the scanning angle range of the light beam, then the detection function is achieved, but the width and depth of the light scanning device must be increased to accommodate both the scanning angle range and the sensor substrate
Solution Approach 1:
The patent repositions the BD sensor from a location outside the scanning angle range to a location inside the scanning angle range, utilizing the angular dimension of the light beam path. This dimensional repositioning allows the sensor to be integrated within the existing optical path footprint, eliminating the need to increase device width and depth while maintaining detection functionality.
Solution Approach 2:
The BD sensor substrate is nested within the scanning angle range of the light beam by strategic positioning. The sensor is placed at a location where it is farther from the deflecting section than the last reflective mirror, allowing the sensor and its substrate to be contained within the angular sweep of the light beam without interfering with the optical path, thus achieving compact integration.
2Volume of moving object
If the BD sensor substrate is arranged within the scanning angle range of the light beam, then the device size is reduced, but the substrate interferes with the light beam
Solution Approach 1:
The patent applies local quality by carefully selecting a specific position within the scanning angle range where the BD sensor substrate does not intersect with the light beam path. The sensor is positioned at a location that is farther from the deflecting section than the last reflective mirror, creating a local zone within the angular range where the substrate can be placed without causing interference, thus maintaining both compact size and optical integrity.
3Loss of time
If the BD sensor is positioned to detect the light beam deflected by the polygonal mirror, then the scanning timing can be synchronized, but the device requires increased width and depth to accommodate the sensor outside the scanning angle range
Solution Approach 1:
The patent utilizes the angular dimension of the light beam path to reposition the BD sensor inside the scanning angle range. By placing the sensor at a specific angular position farther from the deflecting section than the last reflective mirror, the sensor can detect the light beam for timing synchronization while being integrated within the compact device footprint, eliminating the need to increase device width and depth.
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 enables the downsizing of the light scanning device by optimizing its size based on the scanning angle range and enhances detection accuracy while preventing interference with the light beam.
Implementation Method 1
A polygonal mirror (deflecting section) is arranged approximately in the center of the light scanning device. Two optical systems are arranged symmetrical with respect to the polygonal mirror at the center. Respective light beams emitted from the respective light-emitting elements are reflected by the polygonal mirror
Implementation Method 2
The reflective mirror is configured to reflect the light beam and cause the light beam to enter a scan object
Implementation Method 3
The optical sensor is configured to detect the light beam deflected by the deflecting section. The light scanning device is configured to scan the scan object with the light beam and set scanning timing of the scan object using the light beam based on detection timing of the light beam using the optical sensor
Data Source
AI summary
A light scanning device includes: a first semiconductor laser 44a that emits a light beam L1; a polygonal mirror 42 that deflects the light beam L1; a reflective mirror 64a that reflects the light beam L1 deflected by the polygonal mirror 42 and causes the light beam L1 to enter a photosensitive drum 13; and a BD sensor 72 that detects the light beam L1 deflected by the polygonal mirror 42. The light scanning device scans the photosensitive drum 13 with the light beam L1 and set scanning timing of the photosensitive drum 13 using the light beam L1 based on detection timing of the light beam L1 using the BD sensor 72. The BD sensor 72 is arranged in the position farther from the polygonal mirror 42 than the last reflective mirror 64a that reflects the light beam L1 immediately before entering the photosensitive drum 13 and arranged inside a scanning angle range α of the light beam L1 corresponding to an effective scan area of the photosensitive drum 13.