Projector Scanning With Rotating Transmissive Optics for Parallel Light
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Solution Overview
Problem
The use of a polygon mirror in projectors impairs the parallelism of light, leading to inefficient use of light emitted from the light source due to changing incidence angles during scanning.
Innovation Solution
A projector design incorporating a light source unit, a first transmissive optical part with parallel planes of incidence and exit surfaces, and rotating parts to scan an image forming region of a light modulation device, with a control device adjusting light intensity based on image information to optimize light usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a polygon mirror is used to scan light across the image forming region, then the scanning function is achieved, but the parallelism of light is impaired and light efficiency decreases
Solution Approach 1:
The patent removes the polygon mirror from the optical system entirely, replacing it with a rotating mirror that maintains light parallelism while achieving the same scanning function. This extraction of the problematic component resolves the contradiction by eliminating the source of light divergence.
Solution Approach 2:
The patent changes the key parameter of the scanning mirror from a polygon shape (with multiple facets causing light divergence) to a simple rotating mirror shape (maintaining light parallelism). This parameter change in the mirror geometry allows scanning to occur without impairing light efficiency.
2Illumination intensity
If the light source output is increased to compensate for light loss during scanning, then light intensity at the image forming region is maintained, but energy consumption increases
Solution Approach 1:
The patent converts the previously harmful light divergence caused by the polygon mirror into a beneficial situation where light parallelism is maintained. This allows the system to use light more efficiently, achieving the required illumination intensity without increasing energy consumption.
Solution Approach 2:
The control device monitors light intensity at the image forming region and adjusts the light source output accordingly. With the rotating mirror maintaining light parallelism, the feedback control can optimize energy usage by only increasing light source output when necessary, rather than continuously operating at high power to compensate for light loss.
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 design ensures efficient use of light by maintaining parallelism and adjusting light intensity, enhancing light modulation and projection quality.
Implementation Method 1
a first transmissive optical part including a first plane of incidence on which the light emitted from the light source unit is incident, and a first exit surface configured to emit the light incident from the first plane of incidence
Data Source
AI summary
A projector of the present disclosure includes a light source, a transmissive optical part, a rotating part, a light modulation device, and a control device. The light modulation device has an image forming region containing a plurality of pixels. The transmissive optical part rotates about a first rotational axis to scan the image forming region of the light modulation device with light emitted from the light source. The control device selects the light control target pixel based on image information, and performs light control.