High Pressure Discharge Lamp Lighting Control
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Solution Overview
Problem
High pressure discharge lamps experience a reduction in illuminance due to excessive rise in electrode tip temperature, caused by the conical configuration of electrodes and increased mercury levels, leading to increased inter-electrode distance and decreased light condensing rate.
Innovation Solution
Implementing a lighting method that controls the power supply to maintain the electrode tip temperature within a safe range by using a lower power value during the initial lighting interval and gradually increasing to the rated power, ensuring the temperature does not exceed 1.1 times the stable lighting temperature, thereby preventing excessive dissipation and maintaining illuminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the electrode tip portions are formed into conical configurations and the enclosed amount of mercury is increased to improve illuminance, then the amount of luminous flux emitted out of the arc tube is increased, but the electrode tip temperature rises excessively causing accelerated evaporation and increased inter-electrode distance
Solution Approach 1:
The patent applies preliminary action by performing constant current control at a lower power level during an initial lighting interval before transitioning to constant power control at rated power. This preliminary low-power operation prevents excessive temperature rise at the electrode tips during the critical startup phase, thereby preventing accelerated evaporation and maintaining the inter-electrode distance within design specifications.
Solution Approach 2:
The patent implements periodic action by dividing the lighting process into distinct time periods: an initial lighting interval with constant current control at reduced power, followed by a subsequent interval with constant power control at rated power. This temporal segmentation allows the electrode tip temperature to remain controlled during startup while achieving full illuminance performance during stable operation.
2Illumination intensity
If conventional lighting control is used with improved electrode configuration and increased mercury content, then initial illuminance improvement is achieved, but inter-electrode distance exceeds design value due to excessive electrode tip temperature rise
Solution Approach 1:
The patent applies preliminary action by performing constant current control at a lower power level during an initial lighting interval before transitioning to constant power control at rated power. This preliminary low-power operation prevents excessive temperature rise at the electrode tips during the critical startup phase, thereby preventing accelerated evaporation and maintaining the inter-electrode distance within design specifications.
Solution Approach 2:
The patent implements feedback control by monitoring the lighting interval and automatically transitioning from constant current control to constant power control based on elapsed time. This feedback mechanism ensures that the electrode tip temperature remains controlled during startup while achieving full illuminance performance during stable operation, thereby maintaining the inter-electrode distance within design values.
3Illumination intensity
If constant power control at rated power is applied from the beginning, then maximum illuminance is achieved immediately, but electrode tip temperature rises excessively causing accelerated evaporation and increased inter-electrode distance
Solution Approach 1:
The patent applies preliminary action by performing constant current control at a lower power level during an initial lighting interval before transitioning to constant power control at rated power. This preliminary low-power operation prevents excessive temperature rise at the electrode tips during the critical startup phase, thereby preventing accelerated evaporation and maintaining the inter-electrode distance within design specifications.
Solution Approach 2:
The patent implements periodic action by dividing the lighting process into distinct time periods: an initial lighting interval with constant current control at reduced power, followed by a subsequent interval with constant power control at rated power. This temporal segmentation allows the electrode tip temperature to remain controlled during startup while achieving full illuminance performance during stable operation.
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 effectively suppresses the rise in electrode tip temperature, stabilizes the inter-electrode distance, and prevents a reduction in illuminance, ensuring consistent light output in high pressure discharge lamps.
Implementation Method 1
controlling a lamp power supplied to the high pressure discharge lamp according to a predetermined condition that a relational expression t≤1.1T is satisfied, where t is an electrode tip temperature during an initial lighting interval and T is an electrode tip temperature during stable lighting
Implementation Method 2
commencing lighting by applying a predetermined voltage to the pair of electrodes to cause dielectric breakdown to occur therebetween
Implementation Method 3
a high pressure discharge lamp having an arc tube in which mercury is enclosed as a light-emitting material and in which a pair of electrodes are arranged
Data Source
AI summary
After discharge has begun in a high pressure discharge lamp, constant current control is performed so a lamp current becomes 4 [A]. Then, the current supplied to a pair of electrodes in the lamp is controlled so an electrode tip temperature t [degrees C.] at this time and an electrode tip temperature T [degrees C.] during stable lighting satisfy the relationship t [degrees C.]<=1.1 T [degrees C.]. When a power of the lamp reaches a rated power value, power control is changed to constant power control. This method enables suppressing an excessive rise in the temperature of the electrode tips in an initial lighting interval from lighting commencement until stable lighting, thereby preventing an increase in arc length due to melting of the electrode tips. Accordingly, illuminance does not readily decrease, particularly in a lamp unit including a high pressure discharge lamp mounted to a reflecting mirror.