Discharge Lamp Lighting Device Power Control for Flicker Prevention
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Solution Overview
Problem
Discharge lamps in projector systems experience flicker and electrode wear when switching from rated power to low power mode due to unstable arc formation and insufficient electrode substance accumulation, leading to reduced light quality and apparatus reliability.
Innovation Solution
A discharge lamp lighting apparatus with a power supply that controls AC power by inserting a low-frequency component into the basic frequency, maintaining an average power change ratio of 0.01 to 2.1 W/s during mode switching to stabilize arc formation and prevent flicker and electrode wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the power supplied to the discharge lamp is lowered from rated power to low power mode, then the brightness of the screen can be adjusted according to the usage environment, but flicker occurs in the discharge lamp due to unstable arc formation
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the power supply characteristics during mode switching. Specifically, it controls the rate of power change (average power change ratio of 0.01 to 2.1 W/s) and inserts low-frequency components into the power waveform to stabilize the arc during transition from rated power to low power mode, preventing flicker while maintaining brightness adjustment capability
Solution Approach 2:
The patent uses periodic action by inserting low-frequency components into the power waveform at specific intervals during mode switching. This periodic modulation helps stabilize the arc formation process and prevents flicker by maintaining consistent electrical conditions during the transition period
2Loss of energy
If the power supplied to the discharge lamp is lowered from rated power to low power mode, then energy consumption is reduced, but electrode wear increases due to insufficient electrode substance accumulation
Solution Approach 1:
The patent applies parameter changes by controlling the rate of power reduction and inserting low-frequency components during mode switching. This prevents abrupt changes in electrical conditions that would cause insufficient electrode substance accumulation, thereby reducing electrode wear while still achieving energy savings in low power mode
Solution Approach 2:
The patent uses preliminary action by preparing the electrode surface in advance during the mode switching transition. By controlling the power change rate and using low-frequency components, it ensures that electrode substance accumulates sufficiently on the electrode surface before stable low power operation begins, preventing premature electrode wear
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
The solution effectively prevents flicker and electrode wear by maintaining stable arc formation and power supply during mode switching, ensuring consistent light quality and extending the lifespan of the discharge lamp.
Implementation Method 1
supply AC power having a power waveform in which a low-frequency component having a frequency lower than a basic frequency component selected from a range from 60 to 1000 Hz is cyclically inserted into the basic frequency component
Implementation Method 2
arcs A are formed between a pair of the electrodes 90, 91 of the discharge lamp
Implementation Method 3
evaporated electrode substance is accumulated by a halogen cycle at positions where original points of the arcs A
Data Source
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AI summary
Provided is a discharge lamp lighting device, whereby it becomes possible to prevent or suppress the occurrence of flickering during the lighting of a discharge lamp by a second lighting mode in which a lower alternate current electric power than a rated electric power is fed when the switching from a first lighting mode in which an alternate current electric power that is the rated electric power is fed into the second lighting mode is carried out. A discharge lamp lighting device comprises a discharge lamp which has a pair of tungsten-made electrodes each having a protrusion formed at the tip thereof and an electric power feeding device which feeds an alternate current electric power to the discharge lamp, and is characterized in that the power feeding device has a function of switching between a first lighting mode in which a rated electric power is fed to the discharge lamp and a second lighting mode in which a lower electric power than the rated electric power is fed to the discharge lamp to light the discharge lamp and, therefore, can control an electric power to be fed to the discharge lamp under such conditions that the average electric power change rate becomes 0.01-2.1 W/s during a mode switching period in which the switching from the first lighting mode into the second lighting mode is carried out.