Projector Prism System for Compact Volume and Leakage Control
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Solution Overview
Problem
Conventional projectors have a large volume due to physical limitations of digital micro-mirror devices and suffer from light leakage, which reduces image contrast and quality.
Innovation Solution
A projector design incorporating a two-axis tilting digital micro-mirror device, a first prism with a reflecting portion, and a second prism with a low reflecting area to manage light paths and minimize leakage, allowing for reduced volume and improved image contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional digital micro-mirror device with oblique incident direction is used, then the device can receive and reflect incident light, but the volume of the projector increases due to the required inclination angle
Solution Approach 1:
The optical system is segmented into multiple functional components: a first prism for receiving and transmitting incident light, a digital micro-mirror device for reflecting image light, and a second prism for reflecting image light to the lens. This segmentation allows each component to be optimized independently, reducing the overall volume while maintaining functionality
Solution Approach 2:
The patent transitions from a conventional single-plane optical path to a three-dimensional folded optical path using prisms. The first prism receives incident light from below, the DMD reflects at an intermediate angle, and the second prism directs light to the lens, effectively utilizing vertical space to reduce the horizontal footprint and overall projector volume
2Ease of operation
If the digital micro-mirror device is operated in OFF-state, then the device can be controlled, but leakage light is reflected back inside the prisms causing scattering reflection and diffuse reflection that reduces image contrast
Solution Approach 1:
The patent converts the harmful back-reflection of leakage light into a beneficial outcome by designing the second prism with a specific reflective surface that redirects leakage light away from the optical path. The leakage light that would normally cause scattering is now reflected at an angle that prevents it from re-entering the prism system, thereby maintaining image contrast while preserving full DMD control functionality
Solution Approach 2:
The second prism acts as an intermediary element between the DMD and the lens. It not only directs the image light but also serves as a barrier that prevents leakage light from the DMD OFF-state from reflecting back into the optical system, thus mediating the interaction between the DMD control state and the optical path to eliminate harmful scattering effects
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 achieves a compact projector form factor with reduced light leakage, enhancing image display quality and convenience by eliminating scattering reflections and diffuse reflections.
Implementation Method 1
The first prism is disposed between the light source and the digital micro-mirror device for receiving and transmitting the incident light
Implementation Method 2
The intermediate portion is adjoined to the first plane and includes a reflecting portion, wherein the incident light is reflected by the reflecting portion
Implementation Method 3
The digital micro-mirror device receives and reflects the incident light as an image light
Implementation Method 4
The fourth plane is parallel to the second plane for receiving the incident light and reflecting the image light
Implementation Method 5
the sixth plane reflects a leakage light of the image light along a predetermined light path away from the prisms
Data Source
AI summary
A projector includes a light source, a digital micro-mirror device (DMD), a first prism, and a second prism. The light source emits incident light. The DMD reflects the incident light as an image light. The first prism is disposed between the light source and the DMD. The second prism is disposed between the first prism and the DMD. The first prism includes a first plane, a second plane, and an intermediate portion including a reflecting portion. The incident light is reflected by the reflecting portion and then passes through the second plane. The second prism includes a fourth plane, a fifth plane, and a sixth plane. When the DMD is operated in an OFF-state, the image light is reflected to the sixth plane, and the sixth plane reflects a leakage light of the image light along a predetermined light path away from the prisms.