Laser Display Dimming Unit Boundary Timing Detection
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Solution Overview
Problem
Existing display apparatuses using laser scanning methods face challenges in accurately detecting the timing of light amount changes when switching neutral density filters, leading to abrupt brightness changes that can be displeasing to users.
Innovation Solution
A display apparatus with a light source, dimming unit, switching unit, sensor, boundary determiner, and synchronization determiner that detects the timing of light amount changes by determining boundary timing based on temporal characteristics of light amount changes, allowing for precise control of light output and synchronization timing to maintain image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the neutral density filter is switched to adjust the light amount of scanning light, then the brightness of the projected image can be adjusted, but the light amount changes sharply causing abrupt brightness changes that give a displeasing feeling to users
Solution Approach 1:
The system performs preliminary detection of the boundary timing when the neutral density filter switches positions using a photodetector and control circuit. Based on this advance detection, the laser output is adjusted before the actual filter switching occurs, preventing abrupt brightness changes. The control unit calculates the required laser output adjustment in advance and implements it prior to the filter position change, thereby smoothing the brightness transition.
2Object-affected harmful factors
If the output control of light source is used to gradually change the light amount, then abrupt brightness changes can be alleviated, but high accuracy detection of the timing when light amount changes is required
Solution Approach 1:
A photodetector is introduced as an intermediary device to detect the position of the neutral density filter. The photodetector receives a portion of the scanning light and converts it to an electrical signal that indicates the filter's position. This intermediary detection mechanism provides precise timing information about when the filter switches positions, enabling the control system to accurately coordinate laser output adjustments with filter switching events.
3Adaptability or versatility
If multiple neutral density filters with different transmittances are switched, then the brightness adjustment range is expanded, but the complexity of the switching mechanism increases
Solution Approach 1:
The system uses the scanning light itself to detect the position of the neutral density filter through the photodetector. The same light beam that carries the image information is partially diverted to the photodetector, which automatically generates position detection signals without requiring separate detection systems. This self-service approach expands the brightness adjustment capability through multiple filters while keeping the switching mechanism relatively simple, as the detection is performed passively using the existing light path.
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 detection of light amount changes during filter switching, improving image forming processing and minimizing abrupt brightness fluctuations, thus enhancing user experience.
Implementation Method 1
a photodetector to detect position of the neutral density filter
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
A display apparatus (1) includes: a light source (11) configured to emit light; a dimming unit (12) including a plurality of regions having transmittances that are mutually different from one another; a switching unit (13) configured to switch a region of the dimming unit (12) through which the light passes, between the plurality of regions of the dimming unit; a scanning unit (14) configured to scan a scan area (21) at a predetermined frame rate with the light, the scan area having a first area (22) in which an image is formed and a second area (23) different from the first area; a sensor (15) configured to detect a light amount of the light emitted to the second area (23); and a first determiner (16) configured to determine a boundary timing at which the light has passed through a boundary portion between two adjacent regions of the dimming unit (12) based on characteristics of a temporal change in the detected light amount.