Discharge Lamp Current Waveform Control for Electrode Life
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Projectors using discharge lamps for 3D stereoscopic video display face a decrease in lamp life due to electrode protrusion deformation, caused by cyclic dimming operations that lead to insufficient power supply and electrode melting, especially when high-frequency alternating current is used.
Innovation Solution
A projector design that controls the driving current waveform to have alternating periods of high and low luminance with the same polarity, incorporating direct-current and alternating-current patterns to maintain electrode temperature stability and prevent excessive melting, while synchronizing dimming with video signals to reduce crosstalk between left and right eye images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If cyclic dimming operation is performed to increase luminance during shutter opening, then video brightness is improved, but electrode protrusions deform and lamp life decreases
Solution Approach 1:
The patent applies periodic action by implementing cyclic dimming operations synchronized with the active shutter glasses. The discharge lamp luminance is increased during periods when shutters are open and reduced when shutters are closed, creating a periodic luminance pattern that improves video brightness while managing electrode heating cycles to extend lamp life.
Solution Approach 2:
The patent changes the luminance parameter of the discharge lamp dynamically through dimming operations. By adjusting the luminance level in synchronization with shutter opening/closing, the system optimizes both video brightness and electrode temperature management, preventing excessive protrusion deformation.
2Productivity
If high-frequency alternating current is supplied for video signal synchronization, then video display quality is improved, but electrode melting is suppressed and protrusion deformation increases
Solution Approach 1:
The patent utilizes periodic action by synchronizing the dimming operation with the high-frequency video signal and alternating current cycles. This creates periodic intervals where power supply is adjusted, allowing electrode cooling during certain phases while maintaining high-frequency operation for video quality.
Solution Approach 2:
The patent maintains continuous useful action by ensuring that the dimming operation continuously tracks with both the video signal and AC cycles. This continuous synchronization ensures that luminance adjustments are always in phase with the high-frequency operation, preventing electrode protrusion deformation while maintaining video display quality.
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
This approach extends the life of the discharge lamp by improving electrode meltability and maintaining protrusion shape, while ensuring a bright and clear stereoscopic video display.
Implementation Method 1
a discharge lamp (90) configured to emit light
Implementation Method 2
the distal ends of the electrodes are less easily heated
Implementation Method 3
a light modulating element configured to modulate, according to a video signal, the light emitted from the discharge lamp
Implementation Method 4
a projection optical system configured to project the light modulated by the light modulating element on a projection surface
Data Source
AI summary
A projector includes a discharge lamp, a discharge-lamp driving unit, a control unit, a light modulating element, and a projection optical system. The control unit alternately repeats a high luminance period in which a driving current having a relatively large absolute value is supplied to the discharge lamp and a low luminance period in which the driving current having a relatively small absolute value is supplied to the discharge lamp. The control unit controls the discharge-lamp driving unit according to a driving current waveform formed by the control waveform unit including a direct-current waveform pattern in which the driving current in a first high luminance period, the driving current in a first low luminance period immediately after the first high luminance period, and the driving current in a second high luminance period immediately after the first low luminance period have the same first polarity.