Discharge Lamp Ignition Device for Projector Flicker Reduction
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Solution Overview
Problem
Projectors using dynamic color filters face unsightly flickering due to cyclical modulation of lamp voltage caused by returning light, which disrupts the uniformity and stability of the luminous flux, leading to fluctuations in image brightness and quality.
Innovation Solution
A discharge lamp ignition device with a feeder circuit, voltage detection, current detection, and a target lamp current signal generation circuit that acquires multiple lamp voltage signals over a color order cycle to generate a target lamp current signal, minimizing disparity between detected and target currents, and synchronizing lamp voltage detection with polarity reversal to stabilize lamp operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If alternating current drive method is used to control electrode wear and service life, then electrode service life is improved, but image flicker and luminous flux fluctuation occur due to polarity reversal
Solution Approach 1:
The patent applies preliminary action by detecting lamp voltage at strategically timed moments before polarity reversal occurs in the alternating current drive cycle. By measuring voltage at these specific preliminary moments and using this data to calculate target current, the system compensates for the effects of polarity reversal before they cause luminous flux fluctuations, thus maintaining stable image output while preserving the electrode service life benefits of AC drive.
2Duration of action of stationary object
If polarity reversal frequency is increased to control electrode wear, then electrode service life is improved, but image flicker becomes more severe
Solution Approach 1:
The patent implements feedback control by continuously monitoring lamp voltage during the alternating current drive cycle and using this detected voltage information to dynamically adjust the target current calculation. The system feeds back the actual voltage conditions to the control circuit, which then modifies the current command to compensate for polarity reversal effects, thereby suppressing luminous flux fluctuations even at higher polarity reversal frequencies while maintaining electrode service life extension.
3Stability of the object's composition
If lamp voltage detection is performed continuously to maintain stable current control, then luminous flux stability is improved, but measurement accuracy is reduced due to cyclical voltage modulation from returning light
Solution Approach 1:
The patent applies preliminary action by performing lamp voltage detection at specific moments in the color wheel rotation cycle, namely during periods when returning light is minimal or absent. By strategically timing the voltage measurements to occur before or during intervals when the dynamic color filter is in positions that minimize light return to the lamp, the system obtains accurate voltage readings that are not corrupted by cyclical modulation, thereby maintaining both measurement precision and luminous flux stability.
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 avoids unsightly flickering and stabilizes lamp operation, ensuring consistent image brightness and quality by reducing the impact of cyclical lamp voltage modulation from returning light, even during steady operation and polarity reversals.
Implementation Method 1
a voltage detection means that detects the voltage of the discharge lamp and generates a lamp voltage detection signal
Implementation Method 2
a current detection means that detects the current of the discharge lamp and generates a lamp current detection signal
Implementation Method 3
a feeder circuit to supply power to the discharge lamp
Data Source
AI summary
To avoid the phenomenon of unsightly flickering in images projected by the projector, in high pressure discharge lamps—especially in high intensity discharge lamps, such as high pressure mercury lamps, metal halide lamps, and xenon lamps—that are used in projectors, even in the presence of the phenomenon of cyclical modulation of the lamp voltage by the returning the light spectrum when the light reflected by the dynamic color filter returns back through the optical system to the lamp, at least during steady operation of the discharge lamp (Ld), a target lamp current signal generation circuit (Up) acquires multiple lamp voltage detection signal (Sv) over a period that is at least as long as the color order cycle of the dynamic color filter (Of) and generates a target lamp current signal (St) based on the multiple lamp voltage detection signals (Sv) that were acquired.