Projection Display Abnormality Detection and Control
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Solution Overview
Problem
Conventional projection display apparatuses cannot reliably detect abnormalities such as light output issues, overturning, vibration, disassembly, deformation, or breakage of the display apparatus including the case and screen, especially within the effective screen area, which can lead to unintended light leakage and image quality deterioration.
Innovation Solution
A projection display apparatus with a case having a light-shielding function, a modulation light source, a movable aperture, a light valve, a projection optical system, a transmission-type screen, and integrated detecting, warning, and control means to promptly identify and respond to abnormalities by adjusting light output and generating alarms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a laser light source with small light emission area and beam divergence is used, then light energy per unit area increases and focusing efficiency improves, but the risk of light leakage and safety hazards increases
Solution Approach 1:
The patent implements preliminary detection actions before light leakage can occur. Detection units are positioned to monitor the optical path in advance, and the control unit prepares to adjust the aperture or stop the light source immediately upon detecting abnormality, preventing light leakage before it happens
Solution Approach 2:
The patent introduces an intermediary control system between the laser light source and the environment. The control unit acts as a mediator that receives detection signals and mediates the light output by adjusting the aperture or stopping the light source, thereby preventing direct light leakage to the environment
2Reliability
If the optical sensor is located outside the effective screen area, then detection of screen detachment and alignment deviation is possible, but detection of abnormalities within the effective screen area cannot be achieved
Solution Approach 1:
The patent divides the detection system into multiple segments: detection units positioned at different locations (including within the effective screen area), each monitoring specific zones. This segmentation allows comprehensive coverage of both the screen area and surrounding regions, solving the limitation of single-position sensors
Solution Approach 2:
The patent extends detection from a single point (outside screen area) to multiple dimensions by positioning detection units at various locations including within the effective screen area, at the screen edge, and in the optical path. This multi-dimensional arrangement ensures complete abnormality detection coverage
3Reliability
If integrated detection and control means are added to the projection display apparatus, then abnormality detection capability improves, but device complexity increases
Solution Approach 1:
The patent implements multi-functional components that serve multiple purposes. The detection units not only detect light leakage but also monitor screen status and alignment. The control unit integrates multiple functions: receiving detection signals, determining abnormality types, and executing appropriate responses (aperture adjustment or light source stopping), thereby reducing the need for separate dedicated components for each function
Solution Approach 2:
The patent establishes a feedback loop where detection units continuously monitor the system state, send signals to the control unit, which then adjusts the aperture or stops the light source based on detected abnormalities. This automated feedback mechanism reduces the need for complex manual control systems and operators
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 reliable and prompt detection of light output abnormalities and structural issues within the display apparatus, preventing light leakage and ensuring image quality by controlling the light source and warning systems when abnormalities are detected.
Implementation Method 1
a transmission-type screen 29 used for the rear projection type includes a Fresnel lens screen (Fresnel optical element) 2 for bending image light 16 from a projector 1 to a viewer 8 side
Implementation Method 2
a light diffusing means 3 for diffusing the image light in a predetermined dispersion angle range
Implementation Method 3
an optical sensor represented by a photodiode is provided outside an effective screen area (display area) on the screen
Data Source
AI summary
Not only abnormality of a light output to an exterior but also overturning, vibration, disassembly, deformation, or breakage of a display apparatus including a case and a screen are reliably and promptly detected. A projection display apparatus includes a light source (22) for generating illumination light, which is provided in a case (28) having a light-shielding function, a movable aperture (23) for adjusting the amount of illumination light from the light source (22), a light valve (9) for adjusting the amount of light based on an image signal to generate image light for forming an image from the illumination light, a projection optical system (10) for enlarging the image light from the light valve (9), and a transmission-type screen (29) for displaying the image, which is provided to a window of the case (28). The projection display apparatus further includes first to ninth detectors (41 to 49) for detecting the abnormality of the light output of the light source (22) to the exterior and the abnormality of the case (28) or the transmission-type screen (29), a warning and alarm unit (30) for notifying the abnormality by sound or light, and a control unit (32) for controlling an internal operation when the abnormality is detected.