Solid-State Light Source Control During Power Interruptions
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Solution Overview
Problem
Projection-type display devices with solid-state light sources face issues with instant power interruptions, leading to unnecessary shutdowns and inefficient power management, as existing solutions either require continuous minimum power supply or have limited lighting maintenance periods.
Innovation Solution
A control device is implemented in the projection-type display device to detect instant power interruptions and manage the solid-state light source by extinguishing it during the interruption period, reducing power consumption and allowing for longer lighting duration, with options including partial or full extinguishing and pulse-width modulation control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the circuit used for maintaining the lighting state is omitted in the projector including the solid-state light source, then the device complexity is reduced, but the reliability deteriorates because the display stops when an instant interruption occurs and the user may erroneously determine that the projector is out of order
Solution Approach 1:
The patent applies periodic action by intermittently extinguishing the solid-state light source during power interruptions through PWM control. The light source is turned on and off periodically to conserve battery energy while maintaining minimal visibility, allowing the system to extend lighting duration without requiring complex maintaining circuits.
2Reliability
If the circuit used for maintaining the lighting state is included in the projector including the solid-state light source, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The control device performs multiple functions: it detects power interruptions, controls PWM output to the solid-state light source, and manages battery power conservation. By making the control device multi-functional, the patent avoids adding separate maintaining circuits while still ensuring operation continuity during power interruptions.
3Reliability
If the circuits disclosed in JP-A-2004-303507 and JP-A-2002-367791 are used to continuously supply minimum power necessary for lighting the lamp, then the reliability is improved, but the use of energy deteriorates because the efficiency is low and the lighting period is limited
Solution Approach 1:
Instead of continuously supplying minimum power, the patent uses periodic action by intermittently turning the solid-state light source on and off during power interruptions. This PWM-based approach significantly reduces battery power consumption while extending the lighting period, as the light source is only active during brief intervals rather than continuously.
Solution Approach 2:
The patent changes the operating parameters of the solid-state light source by controlling it through PWM with variable duty cycles. During power interruptions, the duty cycle is reduced to extend lighting duration from battery power, and the current supplied is adjusted based on remaining battery capacity, optimizing energy usage without compromising reliability.
4Duration of action of moving object
If precise control is performed to lengthen the lighting period by not allowing power supplied to the lamp to be equal to or lower than the minimum power, then the duration of action is improved, but the device complexity increases because precise control cannot be performed
Solution Approach 1:
The patent changes operational parameters (power supply level, PWM duty cycle) based on detected battery remaining capacity. As battery power decreases, the system automatically adjusts parameters to extend lighting duration without requiring complex precise control mechanisms, simply by modifying the control strategy based on power availability.
Data Source
AI summary
A projection-type display device according to an embodiment of the invention modulates light emitted from a solid-state light source array and projects the modulated light on a screen. The projection-type display device includes a power source device that generates power used for driving the solid-state light source array using power supplied from a power source, an instant interruption detecting circuit that detects an instant interruption of the power source, and a control device that, in a case where the instant interruption of the power source is detected by the instant interruption detecting circuit, performs control of extinguishing the solid-state light source array during at least a part of an instant interruption period until recovery after the detection of the instant interruption of the power source.