JP4311319B2 - Short arc type discharge lamp - Google Patents

Description

  The present invention relates to a short arc type discharge lamp. In particular, the present invention relates to a short arc type xenon lamp in which a xenon gas is sealed in an arc tube, which is employed as a light source for a microchip used for solution analysis by absorptiometry.

In recent years, μ-TAS (μ-Total Analysis System), which performs micromachine technology and makes chemical analysis smaller than conventional devices, and “Lab on
An analysis technique using a microchip called “a chip” has attracted attention. When these are used in the medical field, (1) the burden on the patient can be reduced by reducing the amount of the specimen such as blood, for example. (2) the examination can be performed by reducing the amount of the reagent. (3) Since the apparatus is small, there is an advantage that the inspection can be easily performed. Taking advantage of such advantages, blood analysis devices using microchips are being used as home specifications, and it has been studied to perform blood analysis by the patient's own hands at home.

  According to the spectrophotometric analysis method using a microchip, (1) blood collected by a painless needle is introduced into the chip, and (2) the blood in the chip is subjected to centrifugal separation to separate it into plasma and blood cells. (3) Plasma and reagent are uniformly mixed with a mixer to obtain a measurement solution. (4) The measurement solution is introduced into the detection unit by a suction pump. (5) A light source is supplied to the measurement solution introduced into the detection unit. The concentration of a desired enzyme contained in plasma can be measured by performing a series of operations of measuring the attenuation of light of a specific wavelength by applying light from the plasma. For example, Patent Document 1 discloses an absorptiometric analysis method using a microchip.

For microchips used for spectrophotometric analysis, detection is necessary because the amount of measurement sample and reagent must be kept to a minimum, and a predetermined absorption length is required depending on the type of measurement sample. The area of the light incident / exit surface in the part (the part through which light is transmitted to measure absorbance) is as small as, for example, about 0.5 mm ² and the shape of the detection part is extremely long. And since it is necessary to irradiate light along such a detection part, in order to measure light absorbency correctly, in order to reduce the light which leaks from the detection part side, and to prevent that a measurement error arises in light absorbency by stray light It is necessary to make light with high parallelism incident. Therefore, ideally, it is preferable to use a laser as the light source.

However, in the spectrophotometric analysis method using a microchip, the wavelength used for measuring the absorbance varies from sample to sample, so when using a monochromatic laser, a laser is used depending on the type of sample to be measured. The necessity to prepare is complicated and disadvantageous in terms of cost. Therefore, the light source is preferably configured by using a xenon lamp that emits light in a continuous wavelength range, and a combination of a xenon lamp and a wavelength selection filter for transmitting only a predetermined wavelength.
JP 2003-279471 A JP 2002-373626 A

  As described above, in the spectrophotometric analysis method using a microchip, since light is irradiated to the extremely small and long and thin detection part, in order to prevent measurement errors from occurring in the absorbance, Therefore, it is necessary to use a lamp having high arc stability, specifically, extremely low arc fluctuation. However, the conventional xenon lamp is generally used mainly as a light source for a projector, as shown in Patent Document 2, for example, and in such applications, the arc stability is such that the fluctuation of the arc cannot be visually confirmed. Therefore, the stability of the arc is insufficient as a light source used for the microchip for spectrophotometric analysis. Therefore, when a conventional xenon lamp is used, there is a problem that the absorbance cannot be measured accurately.

  In addition, the light source used for the microchip for spectrophotometric analysis is extremely minute as described above, and light is irradiated onto a long and narrow area, so that the irradiated light is completely absorbed by the measurement sample and the absorbance cannot be detected. It is necessary to have high luminance so that there is no problem. However, as shown in Patent Document 2, the conventional xenon lamp has a large distance between the electrodes (a distance between the anode and the cathode) of about 4 mm, and a shape in which the arc formed between the anode and the cathode is narrowed down. In addition, since sufficient luminance cannot be obtained, it is not suitable as a light source used for a microchip.

  As described above, the present invention provides an optimum light source for use in a microchip for spectrophotometric analysis by minimizing arc fluctuation and increasing brightness in a short arc type xenon lamp. For the purpose.

Short arc type discharge lamp of the present invention includes a light emitting portion with an internal xenon gas of the arc tube having a branch pipe portion connected to both ends are sealed, cathode cathode and anode in the internal space of the arc tube In the short arc type discharge lamp that is disposed so as to face the lower side and the anode on the upper side and is driven to be lit in the vertical direction, the arc tube has a convex part formed on the branch side on the cathode side. The section is connected to the space inside the arc tube and has an auxiliary space into which xenon gas can flow.

  Furthermore, the convex portion is an exhaust pipe remaining portion.

Furthermore, the inner volume of the arc tube is 0.5 cm ³ or less, and the distance between the electrodes is 0.4 mm or less.

  Furthermore, the short arc discharge lamp of the present invention is used as a light source for a microchip.

  According to the short arc type discharge lamp of the present invention, a convex portion having an auxiliary space that is connected to the interior space of the arc tube at the branch side on the cathode side and that is a low temperature location in the space inside the arc tube as compared with other locations. By adopting an extremely simple structure in which the portion is formed, the xenon gas can be cooled to slow down the thermal convection by the xenon gas, and the arc fluctuation can be suppressed.

In particular, the arc tube is an extremely small short arc type discharge lamp having an inner volume of 0.5 cm ³ or less, the rated current is increased to increase the current density at the cathode tip, and the thermal convection of xenon gas in the arc tube is increased. Even when the speed is remarkably increased, the arc fluctuation can be satisfactorily suppressed. Furthermore, by adopting a configuration in which the distance between the electrodes is 0.4 mm or less, the luminance is improved and light can be incident on a minute region.
Therefore, even for extremely small and long thin areas such as the detection part of a microchip, the stability of the arc can be sufficiently ensured to allow parallel light to enter, so the absorbance can be accurately measured. Can do.

FIG. 1 is a view for explaining a short arc type discharge lamp of the present invention. FIG. 1A is a cross-sectional view including the tube axis, and FIG. 1B is a cross-sectional view in the radial direction.
The short arc type discharge lamp 100 includes an arc tube 1 made of, for example, quartz glass. The arc tube 1 includes a spherical light-emitting unit 11 positioned substantially at the center, branch tube units 12 (12a, 12b) connected to both ends of the light-emitting unit 11, and sealing units 13 (13a, 13b) connected to the branch tube unit 12. The xenon gas is sealed in the internal space S. In the internal space S, a pair of the cathode 2 and the anode 3 are arranged to face each other. The cathode 2 includes a large-diameter portion 21 made of tungsten having, for example, thorium oxide as an emitter material, and a shaft portion 22 made of tungsten, for example, connected to the rear of the large-diameter portion 21. The anode 3 includes a large-diameter portion 31 made of tungsten, for example, and a shaft portion 32 made of tungsten, for example, connected to the rear of the large-diameter portion 31. In the sealing portion 13a and the sealing portion 13b, a metal foil 4 made of, for example, molybdenum is embedded to ensure the airtightness of the arc tube 1. This metal foil 4 is electrically connected at one end to the base end portion 23 of the shaft portion 22 or the base end portion 33 of the shaft portion 32 by welding, and outward from the sealing portion 13a or the sealing portion 13b to the other end. An external lead 5 for power feeding made of, for example, tungsten, which protrudes from the wire, is electrically connected by welding.

  Further, the short arc type discharge lamp 100 is connected to the internal space S in the branch-side tube portion 12a on the cathode side, and has a convex space having an auxiliary space H in which xenon gas, which will be described later, can pass heat convection. A portion 14 is formed. The advantage of forming such an auxiliary space H will be described below.

In the short arc type discharge lamp 100, a lighting power source (not shown) is connected to each external lead 5, and power is supplied to the external lead 5, so that dielectric breakdown occurs between the cathode 2 and the anode 3. The lighting is driven in the vertical direction. At the time of lighting driving, an arc is formed between the cathode 2 and the anode 3, and this portion becomes a very hot portion, so that heat convection of xenon gas occurs in the internal space S as shown by the arrow in FIG. . FIG. 2 is a schematic diagram for explaining the thermal convection of xenon gas generated in the internal space S, and the same reference numerals as those in FIG. 1 denote the same parts.
The xenon gas existing around the anode 3 is in a high temperature state due to the collision of electrons emitted from the cathode 2 and the anode 3 becomes extremely hot, and the arrow A rising along the outer periphery of the anode 3. The flow shown by is produced. Then, the raised xenon gas is separated from the anode 3 serving as a heat source and the temperature is lowered, thereby causing a flow indicated by an arrow B that descends along the inner wall of the arc tube 1. And after flowing into the auxiliary space H in the convex part 14 formed in the branch pipe part 12a, the flow shown by the rising arrow C is generated.
The auxiliary space H is far from the anode 3 as a heat source and exists in the convex portion 14 projecting in a convex shape from the ridge line of the branch tube portion 12a, and is the location having the lowest temperature in the arc tube. When flowing into the auxiliary space H, it is considered that the arc is stabilized due to sufficient cooling and a decrease in the speed of heat convection by the xenon gas. That is, in the internal space S, when the xenon gas is in a high temperature state, the arc fluctuates due to the influence of high-speed thermal convection by the xenon gas. By providing the auxiliary space H connected to the internal space S, the xenon gas is By reducing the speed of thermal convection, it is possible to suppress the occurrence of fluctuations in the arc.

  The convex portion 14 is formed on the branch tube portion 12a on the cathode 2 side because the flow of the high temperature xenon gas indicated by the arrow A is above the anode 3 (on the base end portion 33 side). This is because the space does not sufficiently flow into the space, so that the cooling effect cannot be obtained if it is formed in the branch pipe portion 12b on the anode side, and further, the distance from the anode 3 serving as a heat source is to be gained. Because you can.

FIG. 3 is a schematic diagram for explaining a method of manufacturing the convex portion. 3A and 3B, the same reference numerals as those in FIG. 1 denote the same parts.
As shown in FIG. 3A, an exhaust pipe 10 connected to the internal space S is attached to the branch pipe portion 12 a of the arc tube 1. After exhausting the internal space S through the exhaust pipe 10 by a predetermined means, xenon gas is introduced into the internal space S. After that, for example, by heating means such as a gas burner, the vicinity of the root of the exhaust pipe 10 is melted, and as shown in FIG. 3B, a convex portion having an auxiliary space H connected to the internal space S in the branch pipe portion 12a. 14 is formed, and the arc tube 1 is filled with xenon gas in an airtight manner.
By doing so, the convex portion 14 can be formed without any manufacturing waste as compared with other methods, which is advantageous in terms of cost.

Here, numerical examples relating to the short arc type discharge lamp of the present invention will be given below.
The arc tube 1, the maximum outer diameter of the light emitting portion 11 is a 5 mm to 10 mm, for example, 7 mm, internal volume a 0.05cm ³ ~0.5cm ^3, for example, 0.1 cm ^3, the total length Is 5 mm to 10 mm, for example, 8 mm. The convex portion 14 has a height (X) of 1.5 mm to 2.5 mm, for example, 2 mm, and a maximum width (Y) of 1.5 mm to 2.5 mm, for example, 2 mm. The product (volume of the auxiliary space H) is 0.0005 cm ^{3 to} 0.006 cm ³ , for example, 0.002 cm ³ . The inter-electrode distance (L) in the tube axis direction is preferably 0.1 mm to 0.4 mm, for example 0.3 mm. This is because it is extremely difficult to make the thickness less than 0.1 mm in manufacturing, and if it exceeds 0.4 mm, parallel light cannot be efficiently incident on a minute and long thin area such as a detection portion of the microchip. Moreover, a rated current is 1A-3A, for example, 1.7A, a rated voltage is 10V-20V, for example, 12V. Furthermore, the enclosed pressure of xenon gas is 0.5 MPa to 1.5 MPa, for example 0.8 MPa.

  According to the short arc discharge lamp 100 of the present invention as described above, the convex portion 14 having the auxiliary space H connected to the internal space S is formed in the branch tube portion 12a on the cathode 2 side as described above. As a result, arc fluctuations can be suppressed. In particular, as shown in the above numerical example, in the case where the arc tube 1 is extremely small as compared with the conventional xenon lamp, if the rated current is increased to increase the current density at the tip of the cathode 2, the arc tube Since the heat convection of the xenon gas in 1 is remarkably increased in speed, it is effective to adopt the structure of the present invention.

FIG. 4 is a view for explaining a measurement system using a microchip light source using the short arc type discharge lamp of the present invention.
The microchip light source 40 includes a short arc type discharge lamp 100, a collimator lens 41, and a band pass filter 42. The microchip 50 is arranged such that the detection unit 51 faces the light emitting unit of the bandpass filter 42. In such a measurement system, the light radiated from the short arc type discharge lamp 100 is converted into parallel light by the collimator lens 41, passes through the band-pass filter 42 that transmits light in a predetermined wavelength region, and then the microchip 50. The light enters the detection unit 51. And the light which permeate | transmitted the detection part 51 is received by the light receiver 52, and a chemical analysis is performed by detecting the light absorbency in a predetermined wavelength.

  The detection unit 51 of the microchip 50 has a diameter of, for example, 0.5 mm square and a total length of 15 mm, which is extremely small and thin. If the short arc discharge lamp of the present invention, which is extremely small and has high brightness due to the high current density at the cathode tip, is used as the microchip light source 40, parallel light is efficiently incident on the detection unit 51. Can be made.

It is sectional drawing for demonstrating the short arc type discharge lamp of this invention. It is a figure for demonstrating the thermal convection of the xenon gas produced in internal space. It is a figure for demonstrating the manufacturing method of a convex part. It is a figure for demonstrating the measuring system using the light source for microchips using the short arc type discharge lamp of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emission tube 2 Cathode 3 Anode 4 Metal foil 5 External lead 10 Exhaust tube 11 Light emission part 12 Branch pipe part 13 Sealing part 14 Convex part 21 Large diameter part 22 Shaft part 23 Base end part 31 Large diameter part 32 Shaft part 33 Base Edge S Internal space H Auxiliary space

Claims (4)

Xenon gas is enclosed in an arc tube having a light emitting portion and branch tube portions connected to both ends of the light emitting portion, and the cathode and anode are on the lower side and the anode is on the upper side in the inner space of the arc tube. In the short arc type discharge lamp which is arranged so as to be opposed and is driven to be lit in the vertical direction ,
The arc tube has a convex portion formed on the branch side on the cathode side,
The convex portion is connected to the inner space of the arc tube and has an auxiliary space into which xenon gas can flow.   The short arc discharge lamp according to claim 1, wherein the convex portion is an exhaust pipe remaining portion. 2. The short arc type discharge lamp according to claim 1, wherein an inner volume of the arc tube is 0.5 cm ³ or less and a distance between the electrodes is 0.4 mm or less.   4. The short arc type discharge lamp according to claim 1, wherein the short arc type discharge lamp is used as a light source for a microchip.

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