Multi-axis Gimbal Actuator for 4x Pixel Resolution
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Solution Overview
Problem
DLP projection systems face limitations in pixel resolution due to the number of mirrors on the digital micromirror device (DMD), which can be overcome by using an extended pixel resolution (XPR) actuator that displaces the image generated by the DMD to create higher resolution images.
Innovation Solution
A multi-axis gimbal actuator with an optical element that tilts on two axes, positioned in the projection path, refracting the light to displace the image by half a pixel in both vertical and horizontal directions, effectively increasing the resolution by 4 times using hinges placed behind the tilt planes to minimize the actuator's size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an XPR actuator is used to increase pixel resolution by displacing the image, then the resolution is increased by 4 times, but the device complexity increases due to the multi-axis gimbal mechanism
Solution Approach 1:
The patent implements a nested gimbal structure where the first tilt frame is tiltably coupled to the second tilt frame, which is in turn tiltably coupled to the reference frame. This nested arrangement allows multiple degrees of freedom (two tilt axes) to be achieved within a compact, hierarchical structure, resolving the contradiction by organizing complexity in a nested manner that achieves 4x resolution enhancement while maintaining structural coherence.
Solution Approach 2:
The patent introduces a second tilt axis (vertical axis) in addition to the first tilt axis (horizontal axis), transitioning from one-dimensional to two-dimensional image displacement capability. This dimensional expansion enables the optical element to deflect light in both horizontal and vertical directions, achieving 4x pixel resolution enhancement by creating four distinct image positions from a single DMD mirror, thus resolving the resolution-complexity contradiction through spatial dimensionality.
2Manufacturing precision
If the optical element is tilted on two axes to displace the image, then the resolution increases, but the size of the actuator increases
Solution Approach 1:
The nested gimbal configuration allows the first tilt frame and second tilt frame to be arranged concentrically, with the optical element mounted on the first tilt frame that tilts horizontally, and the second tilt frame providing vertical tilting. This nesting minimizes the overall volume by sharing common rotational axes and reducing redundant structural elements, achieving precise bi-axis image displacement without proportionally increasing actuator size.
Solution Approach 2:
The gimbal mechanism employs spherical joint geometry at the tilt axes, allowing rotational movement in multiple directions from a compact pivot point. This spherical configuration enables the optical element to achieve two-axis tilting capability while maintaining a compact form factor, as the spherical joints concentrate the rotational degrees of freedom at centralized pivot points rather than requiring extended linear mechanisms, thus resolving the precision-size contradiction.
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 XPR actuator increases the pixel resolution of the projected image by 4 times without increasing the size of the projector, achieving this through precise tilting of the optical element, which is imperceptible to the human eye at a rate of approximately 60 Hz.
Implementation Method 1
refracting the light to displace the image by half a pixel in both vertical and horizontal directions
Data Source
AI summary
A multi-axis gimbal actuator includes a first tilt frame tiltably coupled to a second tilt frame. The second frame is tiltably coupled to a reference frame. The first tilt frame is offset from the second tilt frame and approximately parallel to the second tilt frame while in a neutral position. An optical element is mounted on the first tilt frame.