High Pressure Discharge Lamp Lighting Apparatus Frequency Control
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Solution Overview
Problem
High pressure discharge lamps experience luminance reduction and projection displacement due to positional changes in the electrode projections when continuously lit, leading to unstable arc discharge and reduced lamp lifetime.
Innovation Solution
A high pressure discharge lamp lighting apparatus that alternates between basic and low frequencies, adjusting the frequency of the low-frequency wave in response to changes in lighting voltage, while gradually increasing and decreasing the period of basic frequency supply to maintain projection stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a constant low frequency is inserted intermittently at a predetermined interval during steady lighting, then the projection temperature can be maintained at an optimal state, but the projection position displaces after continuous lighting for a certain period
Solution Approach 1:
The patent applies dynamics by making the lighting frequency adjustable rather than fixed. The control unit dynamically changes the lighting frequency based on the lighting time duration: using a first frequency (60-1000 Hz) during initial lighting to form projections, then switching to a second frequency (5-200 Hz) after a predetermined period to maintain optimal projection temperature, and finally returning to the first frequency after extended lighting to correct projection displacement. This dynamic frequency adjustment resolves the contradiction between maintaining projection temperature and preventing projection position displacement.
2Reliability
If the lighting frequency is changed in response to lighting voltage changes, then the projection can be generated and maintained as the original point of the arc, but the system complexity increases
Solution Approach 1:
The patent implements feedback control where the control unit continuously monitors lighting voltage and automatically adjusts the lighting frequency in response. When lighting voltage changes occur during steady lighting, the control unit detects this and modifies the frequency from the first range (60-1000 Hz) to the second range (5-200 Hz) or vice versa. This feedback mechanism ensures the projection is maintained as the stable original point of the arc while managing system complexity through automated voltage-based frequency adjustment.
3Illumination intensity
If a low frequency is inserted intermittently at a predetermined interval, then the luminance can be maintained, but blackening occurs on the inner tube walls and lamp lifetime is reduced
Solution Approach 1:
The patent applies periodic action by alternating between different lighting frequencies in a predetermined sequence. During steady lighting, the system periodically switches from the first frequency (60-1000 Hz) to the second frequency (5-200 Hz) after a predetermined time interval, then returns to the first frequency after extended lighting. This periodic frequency variation maintains optimal luminance by preventing projection temperature degradation while reducing blackening on inner tube walls compared to continuous low frequency insertion, thereby extending lamp lifetime.
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 solution suppresses projection displacement, maintains luminance, and extends the lamp's operational life by ensuring optimal arc stability and reducing blackening on the inner tube walls.
Implementation Method 1
A super-high pressure discharge lamp in which at least 0.2 mg/mm3 mercury is enclosed in an interior of a discharge container and configured to increase in pressure to 200 atmospheric pressure or higher at the time of lighting is used for a lamp for a light source for projectors or the like. The high pressure discharge lamp as described above is known to maintain a stable lighting state by forming a projection on a distal end surface of an electrode and retaining an arc on the projection
Data Source
AI summary
In a lighting apparatus containing a high pressure discharge lamp, an alternating current supplied to the discharge lamp at the time of steady lighting of the frequency (basic frequency) selected from a range between 60 and 1000 Hz and a low frequency having a frequency selected from a range between 5 and 200 Hz lower than the basic frequency is generated alternately. The frequency of the low frequency wave is changed in response to the change of the lighting voltage of the discharge lamp. The supply period of the basic frequency is increased and decreased little by little by every predetermined time.