Distance Measuring Device for Projectors Using Elliptical Laser Beam
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Solution Overview
Problem
Conventional projector distance measuring devices have limited measurable ranges due to the deviation of reflected light collection positions, making it difficult to accurately measure distances across a wide range without increasing device size, which is undesirable for miniaturized projectors.
Innovation Solution
A distance measuring device with a light receiving element positioned closer to the light receiving lens than the focal point, allowing reflected light from both far and near positions to be incident on the element, and using an elliptically shaped laser beam to ensure all reflected light from far positions is collected, while part of the light from near positions is also received, without enlarging the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the light receiving element is positioned at the focal point of the light receiving lens, then reflected light from far positions can be collected, but reflected light from near positions cannot be incident on the element
Solution Approach 1:
The patent changes the position parameter of the light receiving element from the focal point to a location closer to the lens. This parameter change allows the element to receive reflected light from both far and near positions simultaneously, expanding the measurable distance range while maintaining measurement accuracy through the lens's optical properties
2Adaptability or versatility
If the size of the light receiving element is increased to expand the incidence range of reflected light, then more reflected light can be received, but the device size increases
Solution Approach 1:
Instead of increasing the size parameter of the light receiving element, the patent changes the position parameter of the element. By positioning it closer to the lens, the same-sized element can receive reflected light from a wider range of distances, achieving expanded incidence range without volume increase
3Adaptability or versatility
If multiple light receiving lenses or a reflection mirror are added to expand the measurable range, then the measurement range is expanded, but the device complexity and size increase
Solution Approach 1:
The patent resolves the contradiction by changing the position parameter of the existing light receiving element rather than adding new components. This single parameter change enables the element to receive reflected light from both far and near positions, expanding the measurable range without increasing device complexity or requiring additional lenses or mirrors
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
Enables accurate distance measurement across a wide range from 5 m to 0.5 m without increasing the light receiving element's size or adding a reflection mirror, facilitating miniaturization and cost reduction, while maintaining high accuracy and preventing dynamic range overload.
Implementation Method 1
light reflected on the distance measuring object
Implementation Method 2
a light receiving lens for collecting reflected light from the distance measuring object
Implementation Method 3
the reflected light is made to be received by the light receiving element for calculation of a distance to the distance measuring object
Data Source
AI summary
There are provided a small distance measuring device which enables an accurate distance measurement and has a wide range of measurable distances and a projector which is provided with the distance measuring device.A projector includes a light source unit, a light source side optical system for guiding light from the light source unit to a display device, the display device, a projection side optical system for projecting an image emitted from the display device on to a screen, and a distance measuring device and has a projector control unit for controlling the light source unit and the display device, and the distance measuring device includes a distance calculating part for calculating distances to a plurality of point on the screen and a mean distance thereof, and the projector control means includes an inclination angle calculating part for calculating an inclination angle of the screen based on the distances to the plurality of points on the screen calculated by the distance calculating part and a distortion correcting part for preparing image data of a projected image which has been corrected for distortion from information calculated by the distance calculating part 45 and the inclination calculating part.