Projection Display Distortion Correction Using Linear Light
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Solution Overview
Problem
Existing projection displays with short focus or ultra-short focus projectors face challenges in correcting image distortion caused by uneven projection surfaces, such as walls, which are common in residential settings, and require inconvenient camera setups for calibration.
Innovation Solution
A projection display system that includes a light irradiator emitting linear light at a shallower angle than the projection light, an imaging unit with a different optical axis capturing the linear light, and a signal processor correcting the distortion based on the captured image, allowing for automatic image correction without the need for a user-placed camera.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate camera is used to capture the projection image for distortion correction, then the measurement precision of surface unevenness improves, but the ease of operation deteriorates due to inconvenient camera placement and setup
Solution Approach 1:
The patent merges the camera function into the projection display device itself. The projection display includes both a projection unit and an imaging unit (camera) integrated in one device, eliminating the need for separate camera placement and setup by the user.
Solution Approach 2:
The projection display performs self-measurement of distortion by using its own integrated camera to capture the projected image. The device automatically detects and measures the distortion caused by surface unevenness without requiring external equipment or user intervention for camera setup.
2Device complexity
If the camera optical axis is aligned with the projection optical axis, then the device complexity is reduced, but the measurement precision of surface unevenness deteriorates due to inability to detect distortion accurately
Solution Approach 1:
The patent deliberately positions the imaging unit's optical axis asymmetrically relative to the projection optical axis. The camera is placed at a specific offset position to capture the projected image from a different viewpoint, enabling accurate detection of distortion caused by surface unevenness.
Solution Approach 2:
The projected image serves as an intermediary between the projection unit and the imaging unit. The camera captures the projected image which contains information about surface unevenness, allowing indirect measurement of distortion through the intermediate projected pattern.
3Measurement precision
If the incident angle of linear light is made shallower than projection light, then the measurement precision of distortion improves, but the device complexity increases due to additional light irradiator and optical path
Solution Approach 1:
The imaging unit serves multiple functions: it captures both the projected image for distortion measurement and the linear light pattern for surface unevenness detection. This multi-functionality reduces the need for separate dedicated components for each measurement task.
Solution Approach 2:
The system alternates between projecting the calibration pattern and emitting linear light, or captures both in sequence. This periodic switching of measurement modes allows the integrated imaging unit to gather different types of information without requiring simultaneous complex optical paths.
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 solution effectively corrects image distortion caused by uneven surfaces, improving image quality while maintaining convenience and ease of use.
Implementation Method 1
a light irradiator that irradiates the projection surface with linear light at an incident angle shallower than an incident angle of projection light
Implementation Method 2
an imaging unit that has an optical axis different from an optical axis of the light irradiator, and performs capturing of the projection surface
Data Source
AI summary
A projection display includes an image display device that displays an image, a projection unit that projects the image displayed by the image display device to a projection surface, a light irradiator that irradiates the projection surface with linear light at an incident angle shallower than an incident angle of projection light, in which the linear light extends along a first direction within the projection surface, an imaging unit that has an optical axis different from an optical axis of the light irradiator, and performs capturing of the projection surface, and a signal processor that performs signal processing on an imaging signal outputted from the imaging unit. The imaging unit performs capturing of the linear light with which the projection surface is irradiated, and the signal processor corrects, on a basis of a captured image of the linear light, a distortion of the projected image.