Discharge Lamp Driving Method for Flicker Prevention
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Solution Overview
Problem
Discharge lamps used in image display apparatuses, such as projectors, experience flicker issues due to the migration of the arc's bright spot, which can be caused by unsuitable electrode projections and low-frequency driving conditions, leading to instability and image quality degradation.
Innovation Solution
A driving device for discharge lamps that includes a frequency modulation section to adjust the alternating current frequency, shortening periods with lower frequencies and lengthening periods with higher frequencies to deform the electrode tips into shapes that prevent flicker, and a flicker detection section to dynamically adjust the modulation based on detected flicker occurrence and deterioration states of the lamp.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If an alternating current with low frequency is supplied to the discharge lamp, then the arc can be formed between projections on electrode tips, but flicker occurs due to migration of the bright spot
Solution Approach 1:
The patent applies dynamics by making the drive frequency variable rather than constant. The frequency modulation section dynamically adjusts the drive frequency between a first frequency (lower than reference frequency) and a second frequency (higher than reference frequency) in periodic alternation. This dynamic frequency change prevents the electrode projections from forming stable shapes that cause flicker, while still allowing arc formation between projections during low-frequency periods.
Solution Approach 2:
The patent implements periodic action through alternating between two drive frequencies in regular cycles. The frequency modulation section creates periodic frequency variations where the drive frequency switches between the first frequency and the second frequency. This periodic frequency modulation prevents continuous accumulation of electrode material in harmful patterns, thereby preventing flicker while maintaining stable arc operation.
2Stability of the object's composition
If the drive frequency is kept low to form projections, then arc formation is enabled, but the period during which low frequency is applied becomes too long causing flicker
Solution Approach 1:
The patent implements periodic action through alternating between two drive frequencies in regular cycles. The frequency modulation section creates periodic frequency variations where the drive frequency switches between the first frequency and the second frequency. This periodic frequency modulation prevents continuous accumulation of electrode material in harmful patterns, thereby preventing flicker while maintaining stable arc operation.
Solution Approach 2:
The patent applies dynamics by making the drive frequency variable rather than constant. The frequency modulation section dynamically adjusts the drive frequency between a first frequency (lower than reference frequency) and a second frequency (higher than reference frequency) in periodic alternation. This dynamic frequency change prevents the electrode projections from forming stable shapes that cause flicker, while still allowing arc formation between projections during low-frequency periods.
3Reliability
If the drive frequency is increased to prevent flicker, then electrode deformation improves, but projection formation becomes insufficient
Solution Approach 1:
The patent implements periodic action through alternating between two drive frequencies in regular cycles. The frequency modulation section creates periodic frequency variations where the drive frequency switches between the first frequency and the second frequency. This periodic frequency modulation prevents continuous accumulation of electrode material in harmful patterns, thereby preventing flicker while maintaining stable arc operation.
Solution Approach 2:
The patent applies dynamics by making the drive frequency variable rather than constant. The frequency modulation section dynamically adjusts the drive frequency between a first frequency (lower than reference frequency) and a second frequency (higher than reference frequency) in periodic alternation. This dynamic frequency change prevents the electrode projections from forming stable shapes that cause flicker, while still allowing arc formation between projections during low-frequency periods.
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 reduces the occurrence and recurrence of flicker by modifying the electrode shape to prevent arc migration, maintaining image stability and quality, even under conditions of low power and advanced lamp deterioration.
Implementation Method 1
the arc used as a luminescent spot is formed between projections provided to the electrodes
Implementation Method 2
the arc used as a luminescent spot is formed between projections provided to the electrodes
Data Source
AI summary
In at least one embodiment of the disclosure, a driving device for a discharge lamp includes an alternating current supply section and a frequency modulation section. The alternating current supply section supplies two electrodes of the discharge lamp with an alternating current. The alternating current comprises a plurality of modulation periods. The frequency modulation section modulates a frequency of the alternating current so as to provide a plurality of retentive periods within each of the modulation periods. Each retentive period has a constant frequency that is different from a frequency of its temporally adjacent retentive periods. The frequency modulation section lengthens a length of at least one of the retentive periods in the modulation period in response to a predetermined condition occurring. The frequency of at least one of the retentive periods is equal to or higher than a predetermined reference frequency.