Electric lamp and discharge devices – With gas or vapor – Three or more electrode discharge device
Reexamination Certificate
2002-02-28
2004-03-16
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
With gas or vapor
Three or more electrode discharge device
C313S558000, C313S595000, C313S601000, C313S234000, C313S581000, C313S042000, C313S039000
Reexamination Certificate
active
06707251
ABSTRACT:
The present invention relates to a flash discharge lamp having high power, high discharge frequency, and a long life expectancy.
BACKGROUND OF THE INVENTION
FIG. 1
shows the interior structure of an embodiment of a flash discharge lamp commonly used in photographic cameras. It comprises a glass tube
11
; a pair of electrodes, i.e., an anode
12
and a cathode
13
, oppositely disposed in at both ends of said glass bulb; a electro-conductive member
14
is provided on the outer surface of the glass tube; a electrode
15
and a triggering electrode
18
mounted on the cathode
13
and xenon gas sealed in said glass tube, wherein the triggering electrode
18
is electrically connected to said electro-conductive member
14
. In operation, when an operating voltage is applied between the two electrodes
12
and
13
, a trigger coil is activated to apply a high trigger voltage to the xenon gas, which is then electro-ionized. Under the action of the field formed between the two electrodes, ions and electrons are accelerated and come into collision with each other so that an electron avalanche effect is created. While all the xenon gas is nearly ionized and a high temperature is produced, a high temperature plasma is formed in the glass tube and emits bright light, which comes close to sunlight, in a short period of time.
The flash discharge lamp undergoes high temperature with each flash. Physical and chemical reactions occur over each component so that the electrodes in the tube become yellow gradually and the brightness decreases gradually.
In the photographic industries, the general life expectancy requirement of a stroboscopic discharge lamp is 3,000 flashes with a flash interval of 15 seconds, where skipping is not allowed. Light output of the flashes cannot be lower than 10% of its original specification before the life ends. In general, the flash discharge lamp can meet the customer criteria. However, in recent years, the demand in the light output has been increased, which leads to an increase of the input power, the discharge temperature of the emitted ions, and the duration of the discharge temperature of the flash discharge lamp. Moreover, as its application has been growing into safety alarms and emergency lighting systems, there is a substantial increase in technical requirement of discharge frequency and longer life span. With the current strobe manufacturing technology, after 15,000 continuous flashes, a sputtering black residue appears on the inner surface of the strobe, the brightness output decreases by more than 30%, blackening appears at the electrode ends and the center of the strobe becomes yellow. With the increase of the discharge frequency, the operational conditions of the flash discharge will go from bad to worse due to the discharge temperature and contamination incurred each flash.
It is an object of this invention to overcome the drawbacks of the prior art, and to provide a flash discharge lamp having the characteristic of higher output power with a longer life span.
Another object of this invention is to provide a flash discharge lamp having a higher discharge frequency.
SUMMARY OF THE INVENTION
To accomplish the foregoing objects, the present invention provides a flash discharge lamp comprising a pair of electrodes i.e. an anode and a cathode, oppositely disposed in at both ends of the glass tube, a electro-conductive member is provided on the outer surface of the glass tube, a triggering electrode mounted on said cathode and electrically connected to said electro-conductive member, and xenon gas sealed in said glass tube, characterized in that said flash discharge lamp further includes at least one high temperature resistant electrode mounted on said cathode and at least one getter electrode mounted on said cathode and/or said anode.
By use of the flash discharge lamps according to this invention, the light output can be multiplied 3 to 10 times. In another words, it can increase the total luminous flux by 3 to 10 times, and the unilateral luminous intensity by 1 to 3 times. The life expectancy of the said lamp is extended by 0.5 to 4 times and up to 10 million times. Moreover, the application of the flash discharge lamp according to this invention has been extended to safety alarms and emergency lighting systems due to the increase in the discharge frequency.
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Chow Lap Lee
Chow Shing Cheung
Colón German
Patel Nimeshkumar D.
Rabin & Berdo P.C.
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