Wheel-Type Optical Assembly Light Shielding for Projector Sensing Accuracy
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Solution Overview
Problem
Interference from diffused illumination light beams in projectors can decrease the accuracy of optical sensing elements used to synchronize the rotation speeds of phosphor and filter wheels, as the wavelength range of the illumination light can overlap with the sensing light beam.
Innovation Solution
A wheel-type optical assembly with a light shielding structure that extends between the optical element and the optical sensing element, preventing diffused light from reaching the sensing element, thereby improving sensing accuracy by shielding the optical sensing element from interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an optical sensing element is used to sense rotation speed of the rotating wheel, then synchronization accuracy is improved, but sensing precision deteriorates due to interference from diffused illumination light beam
Solution Approach 1:
A light shielding structure is introduced as an intermediary element between the optical element and the optical sensing element. This structure blocks the diffused illumination light beam from reaching the sensing element, thereby eliminating the harmful interference while preserving the sensing function. The shielding structure acts as a mediator that separates the illumination path from the sensing path.
Solution Approach 2:
The optical system is segmented into distinct functional zones: an illumination region with the optical element and a sensing region with the optical sensing element. The light shielding structure physically divides these zones, allowing the illumination light beam and sensing light beam to operate independently without interference. This spatial segmentation resolves the contradiction by isolating the sensing element from harmful light diffusion.
2Use of energy by moving object
If the wavelength range of illumination light beam overlaps with sensing light beam, then lighting effectiveness is improved, but sensing precision deteriorates due to light diffusion interference
Solution Approach 1:
The light shielding structure serves as a mediator that allows wavelength overlap between illumination and sensing light beams while preventing spatial interference. By blocking only the diffused illumination light from reaching the sensor (while permitting the direct sensing light beam to pass), the system maintains both illumination effectiveness and sensing precision despite wavelength overlap.
Solution Approach 2:
The light shielding structure applies selective blocking: it blocks diffused illumination light in specific directions while allowing sensing light to reach the sensor. This local quality control ensures that the harmful diffused light is filtered out at the sensing location while the useful illumination function remains intact elsewhere in the optical path.
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
Enhances the accuracy of optical sensing elements by blocking diffused light, ensuring precise synchronization of the rotating wheels and improving the overall performance of the projector.
Implementation Method 1
The light shielding structure is connected to the frame and surrounds the optical sensing element... preventing diffused light from reaching the sensing element
Implementation Method 2
The optical sensing element is arranged on the frame and configured to sense a rotation speed of the rotating wheel
Data Source
AI summary
A projector includes a light source, an optical element, a wheel-type optical assembly, a light valve, and a projection lens. The wheel-type optical assembly includes a frame, a driving unit, a rotating wheel, an optical sensing element, and a light shielding structure. The driving unit is arranged on the frame and connected to the rotating wheel. The driving unit drives the rotating wheel to rotate about a rotation axis. The optical sensing element arranged on the frame senses a rotation speed of the rotating wheel. The light shielding structure connected to the frame surrounds the optical sensing element. An orthographic projection of the light shielding structure on a reference plane partially overlaps an orthographic projection of the rotation axis on the reference plane. A normal line of the reference plane is parallel to a shortest connection line between an optical axis of the optical element and the rotation axis.