JP2003322562A - Ultraviolet ray detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultraviolet ray detecting device constructible in a relatively small shape having no adverse influence between mutually adjacent detectors at detecting time when detecting an ultraviolet ray from flame by using a plurality of kinds of discharge tube type ultraviolet ray detectors different in detectable wave length area. <P>SOLUTION: This ultraviolet ray detector is formed by arranging an anode 11 and a cathode 12 in a discharge tube 10 for passing an ultraviolet ray, and is constituted by filling ionizable gas in the discharge tube 10. A plurality of ultraviolet ray detectors 1, 2, and 3 mutually different in a construction material of the cathode 12 are arranged on the ultraviolet ray incident side. When supplying prescribed voltage to the electrodes 11 and 12 of the respective ultraviolet ray detectors 1, 2, and 3, the voltage is impressed on the adjacent ultraviolet ray detectors by staggering the time so as not to be simultaneous. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet ray detecting device for accurately and efficiently detecting ultraviolet rays generated from a flame in a combustion furnace.

[0002]

2. Description of the Related Art In a combustion furnace, temperature control is performed to adjust the supply amount of air or fuel in order to achieve and maintain a desired temperature. On the other hand, harmful nitrogen oxides (NO _x ) are used. It is required to suppress the generation of carbon monoxide (CO) and the like and to improve the combustion efficiency. Therefore, the air-fuel ratio (ratio indicating the mixing ratio of air and fuel) is detected,
It is considered to control combustion based on that.
As a means therefor, an image measurement and detection device for the air-fuel ratio distribution in the flame has been proposed which includes a camera that receives visible light emitted from the flame and an image processing device that calculates the air-fuel ratio from the image obtained by the camera.

On the other hand, in order to meet the above demands, the temperature of the furnace wall has been increased (600 ° C. to 900 ° C.) and the operation is often performed. At such a high temperature, visible light is radiated not only from the flame in the furnace but also from the furnace wall, and thus the measurement / detection device based on visible light cannot accurately measure the air-fuel ratio. Therefore, it is conceivable to detect ultraviolet rays emitted from the flame in a region having a wavelength shorter than visible light (shorter than 400 nm) and measure the air-fuel ratio based on the detected ultraviolet rays. Therefore, as a means for detecting ultraviolet rays, there are known discharge tube type, photoelectric tube type or Geiger-Muller type ultraviolet ray detectors (hereinafter referred to as "discharge tube type") ultraviolet ray detectors and semiconductor type ultraviolet ray detectors. However, since the ultraviolet rays emitted from the flame as described above are relatively weak, a semiconductor type ultraviolet ray detector having a low sensitivity cannot be used, and it is necessary to use a highly sensitive discharge tube type ultraviolet ray detector.

In a conventional discharge tube type ultraviolet detector, a pair of electrodes (anode and cathode) are installed in a discharge tube through which ultraviolet rays can pass and an ionizable gas (Penning gas) is filled in the discharge tube. It is configured. As the Penning gas, a mixed gas of neon-hydrogen, helium-hydrogen, or neon-argon-hydrogen is used. Then, when a voltage of about 300 V is applied between the pair of electrodes, it becomes a state where ultraviolet rays can be detected (ON state), and when ultraviolet rays hit the cathode, it becomes a discharge state.

In the spectrum distribution of ultraviolet rays from the flame detected by this, waveforms corresponding to respective components such as NO, OH, CH, etc. in the flame appear, and whether the wavelength region in which these waveforms appear can be detected or not. Depends on the material of the electrodes in the discharge tube. That is, the materials of the electrodes used in this type of discharge tube are tungsten (W), nickel (Ni),
Molybdenum (Mo), copper (Cu), iron (Fe), gold (A
u), silver (Ag), tantalum (Ta), carbon (C), and the like, but the detectable wavelength region is determined by which material the cathode (cathode) is made of.

[0006] In such a discharge tube type ultraviolet detector, although the detectable ultraviolet region is limited depending on the material of the electrode, the presence or absence of ultraviolet can be detected, so that the flame inside the combustion furnace is monitored. It is used as a means.

[0007]

However, in order to meet the recent demands for combustion furnaces, NO in the flame,
It is necessary to correctly detect the components such as OH and CH, and if the conventional discharge tube type ultraviolet ray detector is used as a means for detecting the ultraviolet rays emitted from the flame, the following problems occur.

First, in order to detect in the wavelength region in which each component such as NO, OH, and CH in the flame appears, a detector in which the detectable ultraviolet region is determined by the electrode material as described above is used. Therefore, it is necessary to prepare a plurality of types for each wavelength region including those components. And, it is required that a plurality of discharge tube type ultraviolet ray detectors with different wavelength regions that can be detected are closely arranged in a determined place so that the ultraviolet rays emitted from the flame in the furnace can be detected under the same conditions. And need space for their placement.

Further, when a plurality of discharge tube type ultraviolet ray detectors are closely arranged, when one detector discharges due to the incidence of ultraviolet rays, an electromagnetic field is generated along with the discharge and the detector itself. Ultraviolet rays are also emitted from. Adjacent detectors can be adversely affected by those electromagnetic fields and UV radiation, making accurate detection of UV radiation from flames difficult.

In order to prevent the adjacent detectors from adversely affecting each other as described above, visible light is irradiated on the wall surface of the discharge tube so that only ultraviolet rays from the flame in the furnace are incident on each detector. It is conceivable to give a treatment to prevent the reflection of ultraviolet rays or to strengthen the electromagnetic shielding. However, in order to completely remove the adverse effect between the adjacent detectors by such processing and shield, the size of the flame detection unit in the furnace must be increased.

According to the present invention, when ultraviolet rays from a flame are detected by using a plurality of types of discharge tube type ultraviolet ray detectors having different detectable wavelength regions as described above, adjacent detectors adversely affect each other during detection. It is an object of the present invention to provide an ultraviolet detection device that does not fit and that can be configured in a relatively small size.

[0012]

The first aspect of the present invention is as follows.
An ultraviolet detector in which an anode and a cathode are installed in a discharge tube through which ultraviolet rays can pass and an ionizable gas is filled in the discharge tube, and a plurality of ultraviolet detectors having different cathode materials are provided. , Placed on the incident side of ultraviolet rays,
When a predetermined voltage is supplied to the electrodes of each ultraviolet ray detector, the voltage is applied to the adjacent ultraviolet ray detectors at different times so that they do not occur simultaneously.

In the ultraviolet detector of this aspect, it is preferable to apply a voltage in sequence to the electrodes of the plurality of ultraviolet detectors.

Another aspect of the present invention is to provide a discharge tube capable of transmitting ultraviolet rays, an ionizable gas sealed in the discharge tube, an anode installed inside the discharge tube, and an anode. An electrode section composed of a plurality of cathodes made of different materials arranged so as to face each other, and a voltage supply circuit for applying a predetermined voltage to the electrode section, wherein the voltage supply circuit is at least one of the plurality of cathodes. It is characterized in that the voltage is applied between adjacent cathodes not at the same time but at different times.

In the ultraviolet detector of this aspect, it is preferable that the application time of the voltage supplied from the voltage supply circuit to the electrode portion is variable.

[0016]

[Advantageous Effects] According to the first aspect, the predetermined voltage is applied to the plurality of ultraviolet ray detectors having different cathode materials so that the adjacent ultraviolet ray detectors are not shifted at the same time. Therefore, adjacent detectors do not adversely affect each other at the time of discharge, and no electromagnetic shielding or other additional structure is required, so that the entire structure can be made relatively small.

According to another aspect, in one discharge tube, one (common) anode and a cathode made of a plurality of different materials constitute an electrode portion, that is, a plurality of types of detectors are integrated. Since a single discharge tube covers a plurality of ultraviolet ray detection regions, the entire device is made smaller, and it is convenient to handle because it is a single device.

According to the present invention, in any of the above-mentioned modes, it is possible to calculate the air-fuel ratio by detecting the ultraviolet rays emitted from the combustion flame and determine whether the flame state is normal or abnormal. . Therefore, an ultraviolet ray detection device suitable for various purposes such as state diagnosis of a combustion furnace used for quenching and the like and fire detection in various facilities is provided.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of an ultraviolet ray detector according to a first embodiment of the present invention. This detection device is configured by arranging a plurality (three in the illustrated case) of discharge tube type ultraviolet ray detectors 1, 2 and 3 toward the incident side of ultraviolet rays.

Each of the ultraviolet detectors 1, 2 and 3 has a pair of electrodes (anode 1) in a discharge tube 10 made of ultraviolet transmitting glass.
1 and the cathode 12) are arranged in parallel at a predetermined interval and the discharge tube 10 is filled with an ionizable gas (Penning gas), but the cathode (cathode) 12 of each detector is common. Are different materials (in the case shown,
Made of W, Cu, Ag).

The anode 11 is made of a mesh metal material (for example, Mo, Ni, or W). By forming the anode 11 in a mesh shape, ultraviolet rays enter the inside of the discharge tube 10 from the upper end and hit the cathode 12. As described above, this type of ultraviolet detector is in a discharge state when ultraviolet rays hit the cathode while a voltage of about 300 V is applied between the pair of electrodes (on state).
Ultraviolet rays can be measured by detecting the current generated thereby.

In each of the ultraviolet detectors 1, 2 and 3 shown in FIG. 1, a pair of electrodes, that is, an anode 11 and a cathode 12 is provided.
Are metal rod-shaped support members 13 and 1 connected to each.
It is supported in parallel and close relation to the inner upper part of the discharge tube 10 by means of 4.

Each of the ultraviolet detectors 1, 2, 3 is, for example, as shown in FIG.
It is driven by the drive circuit shown in. This drive circuit
As described above, the ultraviolet detectors 1, 2 and 3 having the cathode 12 made of different materials are sequentially driven to the ON state. Each of the detectors is brought into a discharge state by receiving ultraviolet rays in the ON state, and a pulse current from the anode 11 to the cathode 12 is generated.

In the circuit of FIG. 2, the ultraviolet detector 1 and the ultraviolet detector 1 are connected to the secondary side of the transformer 20 on the output side of a voltage circuit including a parallel circuit of a capacitor 21 and a diode 22 and a resistor 23 and a capacitor 24. 2, 3 in parallel, and via the switch circuit 25 provided on each cathode 12 side,
It is configured by connecting a parallel circuit of a resistor 23 and a capacitor 24.

As will be described later, the switch circuit 25 changes the predetermined voltage in the order of the ultraviolet detectors 1, 2 and 3 or changes the voltage depending on the situation (for example, when the amount of ultraviolet rays from the flame is large, the voltage is changed. (For example, several tens of microseconds to several tens of milliseconds) are applied periodically (in alternating current or rectangular waveform) for a predetermined time (for example, several tens of microseconds to several tens of milliseconds).
It may be a mechanical switching means having a movable contact 28 that is switched so as to be sequentially connected to the cathode side terminals of the second and third terminals at predetermined time intervals.

In the circuit of FIG. 2, when the lower terminal of the secondary winding of the transformer 20 is +, the current flows from this lower terminal through the resistor 23 and the diode 22 to the capacitor 21.
Flow to charge to the polarity shown. The secondary voltage of the transformer 20 is added to the voltage of the capacitor 21 in the next half cycle of the alternating current to apply a positive voltage to the anode 11 of the UV detector connected to the movable contact 28 of the switch circuit 25.

In the illustrated example, the secondary voltage is 136 V, the capacitor 21 is 4 μF, the resistor 23 is 5100Ω, and the capacitor 24 is
Are set to 10 μF, and the voltage of the capacitor 21 is 110V.

If no ultraviolet light is present in the state where the AC voltage is applied to the transformer 20, the impedance of the detector 1, 2, or 3 connected to the movable contact 28 of the switch circuit 25 becomes extremely high, and the diode 22 is initially connected. A current flows through and charges the capacitor 21 during the first half cycle. During the next half cycle, little or no current will flow through this circuit. When the voltage is reversed again, only leakage current flows through the diode 22 and the capacitor 21
To keep the battery charged. This leakage current is insufficient to produce the output current.

In the presence of ultraviolet light, the detector conducts for half a cycle of the alternating current applied to the transformer 20, the capacitor 21 being the detector, and the resistor 26 and the capacitor 2.
It discharges through the parallel circuit of 7. When the next half cycle with reversed polarity appears in the transformer 20, the capacitor 21 is recharged via the diode 22.

If the detector remains conductive, the capacitor 21 will alternate between charging and discharging, resulting in a current through the diode 22 every other half cycle. Therefore, a voltage drop occurs in the resistor 23 that is connected in series with this, and this voltage drop charges the capacitor 24,
A voltage develops across it. During this time, the capacitor 27
The voltage across is very small. If a short circuit occurs in the detector, its impedance becomes extremely small, so that the capacitor 21 is charged to a relatively high voltage via the diode 29 connected in parallel with the short circuit. That is,
The extremely high charging voltage of capacitor 21 reverse biases diode 22 every other half cycle, reducing its conductivity. Therefore, the current flowing through the resistor 23 becomes extremely small or becomes zero, so that the charge amount of the capacitor 24 decreases or becomes no charge. When the capacitor 24 becomes uncharged, the voltage across it becomes zero.

As long as ultraviolet rays are incident, the detector is turned off and the capacitor 21 is charged in the half cycle, and the detector is turned on and the capacitor 21 is discharged in the next half cycle.

The parallel circuit of the resistor 26 and the capacitor 27 and the diode 29 constitute short-circuit protection means.

With the switch circuit 25 of FIG. 2, for example,
As shown in FIG. 3, the cathode 12 is made of W, Cu, and Ag, and the ultraviolet detectors 1, 2, and 3 are sequentially applied with a predetermined voltage to a pair of electrodes in each discharge tube for a certain period of time. As described above, the ultraviolet ray detectors 1, 2, and 3 are sequentially turned on (operated), and it is possible to detect the ultraviolet rays in the detectable wavelength region. Specifically, 1 connected to the anode and cathode of each ultraviolet detector 1, 2, 3 respectively
When ultraviolet rays hit the cathode in a state where the AC voltage as shown in FIG. 3 is applied to the pair of terminals, discharge is performed approximately every half cycle of the AC voltage. A signal current as shown in the figure is obtained by this discharge. At this time, the terminal voltage becomes as shown by the broken line.

As shown in FIG. 3, the ultraviolet light detectors do not overlap each other in the application time (ON state) of the voltage supplied to the plural ultraviolet light detectors having different cathode materials, and one ultraviolet light detector is not detected. It is preferable to take a state in which none of the detectors is turned on (OFF) after turning on the other one and then turn on another detector.

FIG. 4 shows an emission spectrum (wavelength characteristic) in a wavelength region in which components such as NO, OH and CH in a flame which is a detection target of the present invention appears. This acetylene on the burner - which is an example of a nitrous oxide (N 2 _O) flame. As shown in the figure, when the wavelength is about 260 (nm) or less, NO,
OH in the region of approximately 260 to 310 (nm), approximately 310 to 400
In the region of (nm), components such as CH and CN strongly appear.

On the other hand, the work function (Φ) and the wavelength are classified as follows according to the kind (material) of the electrodes of the discharge tube type detector as described above.

Φ 1 = 4.52 eV (W), 4.61 to 5.24 eV
(Ni), 4.2 eV (Mo) Wavelength = 270, 270 to 236, 294 (nm) Φ2 = 3.85 to 4.38 eV (Cu), 4.04 to 4.77 eV (F
e), 4.0 to 4.58 eV (Au), 4.07 to 4.19 eV (T
a), 4.39 eV (C) Wavelength = 320 to 280, 306 to 260, 309 to 270, 303 to 295
, 281 (nm) Φ3 = 3.08 to 3.56 eV (Ag), 2.98 to 4.43 eV (A
l), 2.24 eV (Ca) wavelength = 400 to 347, 414 to 279, 551 (nm) Therefore, in the emission spectrum of FIG. 4, NO in the flame is detected in the wavelength range of 200 to 250 nm, so work The output of the function Φ1 is F1 = f1
(Φ1). Since OH in the flame is detected in the wavelength range of 260 to 310 nm, the output is F2 = f2 at the electrode with work function Φ2.
(Φ2) -k1 · F1. [K1 is a correction coefficient] CH in the flame is detected in the wavelength region of 314 to 390 nm, so the output is F3 = f3 at the electrode of work function Φ3.
(Φ3) −k2 · F2−k3 · F1. [K2 and k3 are correction factors] From the above, the work function Φ1 according to the electrode material mainly captures the NO group, the work function Φ2 captures OH and NO, and the work function Φ3
Can be said to capture NO, OH, CH, CN, C, etc.

Therefore, as in the above-mentioned embodiment, by detecting the ultraviolet rays by a plurality of ultraviolet ray detectors, each cathode being made of a different material (for example, W, Cu, Ag),
By obtaining an emission spectrum in the wavelength region corresponding to those materials, the amount of components such as NO and CH in the flame (the intensity ratio thereof) can be calculated.

On the other hand, the emission intensity due to combustion and the air ratio have a fixed relationship as shown in FIG. This is, for example, N in a mixed gas of CH ₄ (methane) and air generated when air is supplied and burned using natural gas as a fuel.
It shows the relationship between the spectral intensity (ratio) of O, OH and CH groups and the equivalence ratio (reciprocal of the air ratio). Here, the air ratio is the minimum amount of air (that is, oxygen) required to completely burn the fuel (that is, 1), and theoretically, this is the required amount of air, but The air may not mix well with the fuel, and as mentioned above,
Since it burns at a higher temperature, a large amount of air is supplied.
That is, the target air ratio is set higher than 1. Then, at the time of combustion, since the supply amount of air or fuel is controlled so that the air ratio takes a target value, it is necessary to detect the actual air ratio.

Therefore, according to the ultraviolet detector of the present invention,
Since the emission intensity ratio of NO and CH in the flame is calculated as described above, the air ratio is obtained from the calculation result based on the above relationship.

Next, another embodiment will be described.

FIG. 6 is a schematic diagram of the detection apparatus including the plurality of ultraviolet ray detectors shown in FIG.
A low-pass filter or a band-pass filter (hereinafter, referred to as a band-pass filter) that passes only ultraviolet rays longer than a predetermined wavelength in front of the light entrance portions (upper end surfaces of the discharge tubes 10 in FIG. 1) of the ultraviolet detectors 2 and 3 made of Ag Will be described in the case of using a "low-pass filter").

According to this structure, as shown in FIG. 7, the wavelength regions detected by the ultraviolet detectors 2 and 3 are each within a predetermined wavelength (for example, 250 nm for Cu and 280 nm for Ag). Is cut. This allows
In the ultraviolet region on the short wavelength side, only the ultraviolet detector 1 whose cathode 12 is made of W detects, and in the wavelength region larger than that, the ultraviolet detectors 2 and 3 provided with the low-pass filter 15 detect. In addition, it is possible to detect in the ultraviolet region divided according to the characteristics of each detector.
On the other hand, the spectra of the components such as NO, OH, and CH appear separately for each of the regions divided as described above, so that those components can be reliably detected by the detector corresponding to each region. That is, the effect of improving the detection or analysis accuracy of the ultraviolet detection device is obtained by such spectroscopy.

FIG. 8 shows an ultraviolet ray detector according to the second embodiment of the present invention. This detection device is common to the first embodiment in that the ionization gas (Penning gas) is filled in the discharge tube 30 made of ultraviolet-transparent glass, but it is installed inside the discharge tube 30. One anode (anode) 31 made of a mesh-shaped metal material, and a plurality of cathodes (three in this case) made of different materials so as to face each other.
The difference from the first embodiment is that 32 are arranged to form one discharge tube type detector.

The three cathodes 32 are made of W, Cu, and Ag, and the one common anode 31 constituting the electrode portion and each cathode 32 are constituted by, for example, the drive circuit shown in FIG. By the voltage supply circuit (not shown), adjacent cathodes 32 are applied with voltage not at the same time but at different times.

For the same purpose as shown in FIG. 6,
On the upper end surface of the discharge tube 30, a low-pass filter 15 that passes only ultraviolet rays longer than a predetermined wavelength is arranged at a position corresponding to the cathode 32 made of Cu and Ag therein.

The ultraviolet ray detecting device of the above embodiment is not limited to the flame in the combustion furnace, but also detects an abnormality in the flame in a cooking or cooking area where a fire is used, detects the state of ignition flame in an automobile engine,
Alternatively, it can be preferably used for flame detection for preventing a fire.

For example, in order to prevent fires, in a work place where an infrared stove is used or welding is performed, a considerable amount of light is emitted from the stove or the welding point, so that a normal photodetector may cause erroneous detection. The above-mentioned ultraviolet ray detection device detects not the light but the ultraviolet rays emitted from the flame that can develop into a fire, so that the occurrence of a flame that causes a fire can be detected at an early stage.

FIG. 9 is a flow chart showing an example of a flame detecting method when the ultraviolet ray detecting device of the above embodiment is used for preventing fire. This method is the same as the first embodiment or the second embodiment.
In the embodiment, it is carried out by processing a signal current generated by three kinds of cathodes (made of W, Cu and Ag) which are discharged when ultraviolet rays are incident, by a computer or other processing device.

Specifically, in FIG. 9, first, W,
Whether the detector is a flame or a flame is determined by whether or not a detector having a cathode made of Cu or Ag detects ultraviolet rays. That is, it is checked in ST1 whether or not it is detected by the W cathode, and if “Yes”, the signal amount (amount of ultraviolet ray) is measured (ST2), and in the next ST3, it is detected by the Cu cathode. If it is also “Yes”, the signal amount (ultraviolet amount) is measured (ST4), and in the next ST5, it is checked whether or not it is detected by the Ag cathode.
If this is also “Yes”, the signal amount (amount of ultraviolet rays)
Is measured (ST6). In the above cases, since ultraviolet rays have been detected by all the detectors, it is determined that the flame is a flame (ST7). Then, based on the signal amount detected and measured by each detector, the above-mentioned "air ratio" is calculated (ST8), and it is determined whether or not the obtained air ratio is within the set value ( ST9) If "Yes", the flame is judged to be proper and the initial standby state is returned. On the other hand, when the obtained air ratio is not within the set value, it is judged to be abnormal and an alarm is issued (S
T10). If none of the above detectors detect ultraviolet rays, it is determined that the flame is not present (ST1
1) Return to the initial standby state.

Although the embodiment has been described above, the present invention is not limited to this, and an arbitrary configuration can be adopted by using a discharge tube type detector having a different detectable region depending on the material of the electrode.

[Brief description of drawings]

FIG. 1 is a diagram showing an ultraviolet detection device according to a first embodiment of the present invention.

2 is a diagram showing an example of a drive circuit for detecting ultraviolet rays by applying a predetermined voltage to three ultraviolet ray detectors in the embodiment of FIG.

FIG. 3 is a diagram showing an operation of detecting ultraviolet rays when the three ultraviolet ray detectors of FIG. 1 are sequentially turned on.

FIG. 4 is a diagram showing an emission spectrum in a wavelength region in which components such as NO, OH, and CH appear in a flame to be detected.

FIG. 5 is a graph showing the correlation between the emission intensity of components generated by combustion and the air ratio.

FIG. 6 is a diagram showing a configuration in which a low-pass filter is provided in front of a light entrance portion of a detector whose cathode is made of Cu or Ag among the three ultraviolet detectors shown in FIG. 1;

7 is a diagram showing changes in the wavelength region of ultraviolet rays detected by a detector provided with the low-pass filter shown in FIG.

FIG. 8 is a diagram showing an ultraviolet ray detection device according to a second embodiment of the present invention.

FIG. 9 is a flowchart showing a procedure of flame detection processing using the ultraviolet ray detection device according to the embodiment.

[Explanation of symbols]

1, 2, 3 ... Ultraviolet detector, 10 ... Discharge tube, 11 ... Anode, 12 ... Cathode, 13, 14 ... Electrode support member, 15 ... Low-pass filter, 30 ... Discharge tube, 31 ... Anode, 32 ... Cathode.

Continued front page    (72) Inventor Yoshikazu Nishino             2-12-19 Shibuya, Shibuya-ku, Tokyo Co., Ltd.             Yamatake (72) Inventor Kenjiro Tanaka             2-12-19 Shibuya, Shibuya-ku, Tokyo Co., Ltd.             Yamatake (72) Inventor Tetsuya Yamada             2-12-19 Shibuya, Shibuya-ku, Tokyo Co., Ltd.             Yamatake (72) Inventor Keisuke Sumiyoshi             2-12-19 Shibuya, Shibuya-ku, Tokyo Co., Ltd.             Yamatake F term (reference) 2G065 AB05 BA16 BB27 BC02 BC14                       BC22 BC35 BD06 CA01 CA12                       DA06

Claims (3)

[Claims] 1. An ultraviolet detector comprising an anode and a cathode provided in a discharge tube capable of transmitting ultraviolet rays, and a discharge tube filled with an ionizable gas, wherein the cathodes are made of different materials. The UV detectors are placed on the incident side of UV rays, and when supplying a predetermined voltage to the electrodes of each UV detector, apply the voltage to the adjacent UV detectors with staggered times so that they do not occur simultaneously. Ultraviolet ray detection device characterized by. 2. The ultraviolet detector according to claim 1,
An ultraviolet ray detection device, wherein the voltage is sequentially applied to electrodes of the plurality of ultraviolet ray detectors. 3. A discharge tube capable of transmitting ultraviolet rays, an ionizable gas sealed in the discharge tube, one anode installed inside the discharge tube, and an anode disposed opposite to the anode. An electrode section composed of a plurality of cathodes made of different materials and a voltage supply circuit for applying a predetermined voltage to the electrode section are provided, and the voltage supply circuit is provided for at least adjacent cathodes of the plurality of cathodes at the same time. Instead of the above, the ultraviolet detection device is characterized in that the voltage is applied at a different time.