Projector Stabilizing Irradiation Beam Intensity via Temporal Modulation
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Solution Overview
Problem
The existing projector technologies using the LLP method face challenges in maintaining a stable intensity distribution of the irradiation beam, leading to instability in touch detection and detection signals due to the high coherence of laser light sources.
Innovation Solution
The projector employs temporal light-quantity modulation of the light source to reduce the coherence of the irradiation beam, stabilizing its intensity distribution by varying the drive current of the infrared light source, which reduces interference and unevenness in the beam's intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a laser light source is used to generate the irradiation beam for LLP method, then the detection sensitivity and touch operation responsiveness are improved, but the intensity distribution of the irradiation beam becomes unstable due to high coherence
Solution Approach 1:
The patent applies periodic modulation to the laser light source at a frequency of 100 Hz to 10 kHz. This periodic action disrupts the high coherence of the laser beam, converting it into partially coherent light with stabilized intensity distribution while maintaining the detection sensitivity required for touch operation functionality
Solution Approach 2:
The patent changes the coherence parameter of the laser light by modulating its intensity periodically. This parameter change transforms the light from highly coherent to partially coherent state, resolving the contradiction between detection sensitivity (which requires coherence) and intensity stability (which suffers from coherence)
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 approach results in stable object detection by minimizing planar and temporal unevenness of the irradiation beam, enhancing the accuracy and reliability of touch operations.
Implementation Method 1
an illumination control section that performs temporal light-quantity modulation of the light obtained from the light source to cause coherence of the irradiation beam to be reduced
Implementation Method 2
performs temporal light-quantity modulation of the light obtained from the light source to cause coherence of the irradiation beam to be reduced
Implementation Method 3
When a detection object such as a finger moves across the membrane-shaped irradiation beam, scattered light is generated at the location that the object moves across. The scattered light is detected as detection light by the use of a camera
Data Source
AI summary
A projector with a detection function according to the present disclosure includes: a projection optical system that projects image light on a projection plane; an irradiation optical system that generates an irradiation beam on the basis of light obtained from a light source, and outputs the irradiation beam, in which the irradiation beam is used for detection of a detection object on the projection plane, and the detection object is configured to be detected; an imaging device that scattered light of the irradiation beam derived from the detection object enters; and an illumination control section that performs temporal light-quantity modulation of the light obtained from the light source to cause coherence of the irradiation beam to be reduced.