JP7492060B1 - Ultraviolet Detector - Google Patents

Abstract

[Problem] To provide an ultraviolet detection device capable of improving resistance to vibration or impact. [Solution] The ultraviolet detection device comprises a container 10 in which a discharge gas G is sealed, an ultraviolet detection tube 2 having a pair of electrodes 21, 22 arranged in the container 10, and current-carrying parts 23, 24 electrically connected to the pair of electrodes 21, 22, respectively, and extending to the outside of the container 10 along a predetermined direction, a circuit board 3 provided with a drive circuit 32 for driving the ultraviolet detection tube 2, and a housing 4 that houses the ultraviolet detection tube 2 and the circuit board 3 and has a light introduction part 41 through which light LT incident on the ultraviolet detection tube 2 is introduced. The circuit board 3 is fixed to the housing 4, and the ultraviolet detection tube 2 is held by the housing 4 on one side S1 in the predetermined direction, and is held by the circuit board 3 at the current-carrying parts 23, 24 on the other side S2 in the predetermined direction. [Selected Figure] Fig. 3

Description

The present invention relates to an ultraviolet detection device.

Patent Document 1 describes a flame detector that detects the presence or absence of a combustion flame in a combustion device such as a burner. In the configuration described in Patent Document 1, an ultraviolet detection tube is arranged so as to be suspended above the bottom plate within a recess defined by the cylindrical outer wall and the bottom plate.

JP 2002-61836 A

In flame detectors such as those described above, the ultraviolet detection tube is easily affected by vibrations and shocks that the flame detector receives. If such effects cause deformation or damage to the internal structure of the ultraviolet detection tube, such as the electrodes, this may deteriorate the characteristics or cause malfunctions. In addition to the internal structure, such effects may also cause damage to the container of the ultraviolet detection tube. For this reason, there is a demand for improved resistance to vibrations and shocks.

The present invention aims to provide an ultraviolet detection device that can improve resistance to vibration or impact.

The ultraviolet detection device of the present invention is [1] "an ultraviolet detection device comprising: a container filled with a discharge gas; an ultraviolet detection tube having a pair of electrodes arranged in the container; at least two current-carrying parts each electrically connected to the pair of electrodes and extending outside the container along a predetermined direction; a circuit board provided with a drive circuit for driving the ultraviolet detection tube; and a housing that contains the ultraviolet detection tube and the circuit board and has a light introduction part through which light incident on the ultraviolet detection tube is introduced, the circuit board being fixed to the housing, and the ultraviolet detection tube being held by the housing on one side of the predetermined direction and held by the circuit board at the current-carrying parts on the other side of the predetermined direction."

In this ultraviolet detection device, the ultraviolet detection tube is held by the housing on one side in a predetermined direction, and is held by the circuit board at the current-carrying section on the other side in the predetermined direction. This allows the ultraviolet detection tube to be securely held by the housing on one side in the predetermined direction, and also allows the ultraviolet detection tube to be securely held by the circuit board fixed to the housing on the other side in the predetermined direction. In this way, by holding the ultraviolet detection tube on both one side and the other side in the predetermined direction, it is possible to effectively increase resistance to vibration and impact. Therefore, with this ultraviolet detection device, it is possible to improve resistance to vibration and impact.

The ultraviolet detection device of the present invention may be [2] "the ultraviolet detection device described in [1] in which an elastic member is interposed between one side of the ultraviolet detection tube in the predetermined direction and the housing." In this case, the resistance to vibration or impact can be further improved.

The ultraviolet detection device of the present invention may be [3] "the ultraviolet detection device described in [2] in which the elastic member is arranged so as not to overlap the pair of electrodes when viewed from the predetermined direction." In this case, it is possible to prevent the elastic member from blocking light incident on the electrodes, and to prevent a decrease in sensitivity.

The ultraviolet detection device of the present invention may be the ultraviolet detection device described in [4] or [3], in which "the container has a cylindrical portion having a center line along the predetermined direction, and a curved portion that is disposed on one side of the cylindrical portion in the predetermined direction and curved so as to be convex toward the one side, and the elastic member is in contact with the curved portion." In this case, the ultraviolet detection tube can be held more firmly than when, for example, the elastic member is in contact with the side surface of the cylindrical portion.

The ultraviolet detection device of the present invention may be [5] "an ultraviolet detection device according to any one of [2] to [4], in which the container has a cylindrical portion having a center line along the predetermined direction, and the elastic member is arranged so as to overlap the edge of the cylindrical portion when viewed from the predetermined direction." In this case, the ultraviolet detection tube can be firmly held while preventing the elastic member from blocking light incident on the electrode and reducing sensitivity.

The ultraviolet detection device of the present invention may be [6] "an ultraviolet detection device according to any one of [1] to [5], in which a gap is provided between the other side of the container in the predetermined direction and the circuit board." In this case, it is possible to prevent the container from coming into contact with the circuit board and being damaged by vibration or impact.

The ultraviolet detection device of the present invention may be [7] "an ultraviolet detection device according to any one of [1] to [6], in which the ultraviolet detection tube is arranged so that a portion on one side in the predetermined direction faces the light introduction part of the housing." In this case, the ultraviolet detection tube can be arranged with suitable directivity.

The ultraviolet detection device of the present invention may be [8] "an ultraviolet detection device according to any one of [1] to [7], which includes a first light-emitting element that outputs ultraviolet light having a wavelength included in the wavelength sensitivity range of the ultraviolet detection tube, the first light-emitting element being a semiconductor light-emitting element." In this case, it is possible to perform a highly accurate check of the operation of the ultraviolet detection tube. That is, for example, the desired wavelength can be obtained more reliably than when a discharge tube is used as the light-emitting element.

The ultraviolet detection device of the present invention may be [9] "the ultraviolet detection device described in [8] further comprising a determination unit provided on the circuit board and determining the operating state of the ultraviolet detection tube based on the output signal of the ultraviolet detection tube accompanying the operation of the first light-emitting element." In this case, the operational reliability of the ultraviolet detection device can be improved by determining the operating state, including checking the operation of the ultraviolet detection tube.

The ultraviolet detection device of the present invention may be [10] "an ultraviolet detection device according to [9], further comprising a second light-emitting element that outputs light having a longer wavelength than the ultraviolet light output by the first light-emitting element, and the judgment unit judges the operating state of the ultraviolet detection tube based on the output signal of the ultraviolet detection tube accompanying the operation of the first light-emitting element and the output signal of the ultraviolet detection tube accompanying the operation of the second light-emitting element." In the ultraviolet detection tube, not only a defect of not responding to light, but also a defect of reacting to light of a wavelength range longer than the target wavelength range (ultraviolet region) due to aging or the like may occur. In the ultraviolet detection device of [10], for example, by setting the wavelengths of the light from the first light-emitting element and the second light-emitting element so that the ultraviolet detection tube reacts to the light from the first light-emitting element while not reacting to the light from the second light-emitting element when the ultraviolet detection tube is operating normally, and the ultraviolet detection tube reacts to both the light from the first light-emitting element and the light from the second light-emitting element when the ultraviolet detection tube is not operating normally, the occurrence of the latter defect described above can be grasped.

The ultraviolet detection device of the present invention may be [11] "an ultraviolet detection device according to any one of [8] to [10], in which an elastic member is interposed between a portion of the ultraviolet detection tube on one side in the predetermined direction and the housing, and the elastic member is located on one side in the predetermined direction with respect to the pair of electrodes." In this case, it is possible to prevent the light from the first light-emitting element from being blocked by the elastic member, and the light from the first light-emitting element is more likely to enter the electrodes.

The ultraviolet detection device of the present invention may be [12] "an ultraviolet detection device according to any one of [8] to [11], in which the first light-emitting element is arranged on the circuit board so as to output the ultraviolet light toward one side of the predetermined direction, and a portion of the housing located between the ultraviolet detection tube and the first light-emitting element when viewed from the predetermined direction has a higher light reflectance than other portions of the housing." In this case, by fixing the first light-emitting element to the circuit board in a stable state, the resistance to vibration or impact is improved, and the light from the first light-emitting element is reflected at that portion of the housing and is more likely to enter the ultraviolet detection tube.

The present invention makes it possible to provide an ultraviolet detection device that can improve resistance to vibration or impact.

FIG. 1 is a perspective view of an ultraviolet ray detection device according to an embodiment. FIG. 2 is a perspective view showing the inside of the ultraviolet detection device. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2.

The following describes in detail an embodiment of the present invention with reference to the drawings. In the following description, the same or equivalent elements are designated by the same reference numerals, and duplicate descriptions are omitted.

As shown in Figures 1 to 3, the ultraviolet detection device 1 includes an ultraviolet detection tube 2, a circuit board 3, and a housing 4. The ultraviolet detection device 1 is used, for example, to monitor combustion in a boiler, monitor misfires in places where hazardous materials are handled, detect misfires or fires in warehouses or facilities, and detect discharges in power plants. The following description will be given with reference to the X, Y, and Z directions (predetermined directions) shown in each figure. The Y direction is perpendicular to the X direction, and the Z direction is perpendicular to the X and Z directions. Also, reference will be made to one side S1 (upper side in each figure) and the other side S2 (lower side in each figure) in the Z direction. The other side S2 is opposite to the one side S1.

The ultraviolet detection tube 2 comprises a container 10, an anode 21 (electrode), a cathode 22 (electrode), two anode current-carrying parts 23, and two cathode current-carrying parts 24. The container 10 is a tubular sealed container, and has a stem part 11 and a bulb part 12. In this example, the stem part 11 and the bulb part 12 are integrally formed from a material that is ultraviolet-transmitting. Examples of such materials include borosilicate glass, ultraviolet-transmitting glass, and quartz glass. The container 10 is hermetically sealed, and discharge gas G is enclosed within the container 10.

The stem portion 11 is formed, for example, in the shape of a circular plate. A protrusion 11a is formed in the center of the stem portion 11, protruding toward the other side S2 in the Z direction. The valve portion 12 has a cylindrical portion 13 and a curved portion 14 (Figure 3). The cylindrical portion 13 has a center line along the Z direction. The cylindrical portion 13 extends from the stem portion 11 to one side S1 in the Z direction. The curved portion 14 is disposed on one side S1 in the Z direction relative to the cylindrical portion 13, and is connected to the cylindrical portion 13. The curved portion 14 is curved, for example, spherically, so as to be convex toward the one side S1.

The anode 21 has an anode body 21a and two anode joints 21b. The anode 21 is made of a metal material such as tungsten, nickel, molybdenum, copper, stainless steel, or Kovar metal. The anode body 21a is formed, for example, in a rectangular plate shape and is arranged perpendicular to the Z direction. In the center of the anode body 21a, a plurality of holes 21c are formed that penetrate the anode body 21a along the Z direction. The plurality of holes 21c are arranged, for example, in a two-dimensional regular arrangement with a certain interval between them. The anode joint 21b is formed in a tab shape (rectangular shape) and extends from the anode body 21a to the other side S2 in the Z direction. The two anode joints 21b are respectively arranged at a pair of corners located diagonally in the anode body 21a.

The cathode 22 has a cathode body 22a and two cathode junctions 22b. The cathode 22 is formed of a metal material such as tungsten, nickel, molybdenum, copper, or Kovar metal. The cathode body 22a is formed, for example, in a rectangular flat plate shape, and is arranged perpendicular to the Z direction so as to face the anode body 21a in the Z direction. The cathode body 22a is located on the other side S2 in the Z direction relative to the anode body 21a.

Unlike the anode body 21a, the cathode body 22a has no holes. In the ultraviolet detection tube 2, light passing through the hole 21c of the anode body 21a is incident on the surface 22c of the cathode body 22a. The surface 22c is the surface (flat surface) of one side S1 in the Z direction of the cathode body 22a (FIG. 3) and functions as a photocathode. The surface 22c emits photoelectrons in response to the incidence of ultraviolet light. The cathode junction 22b is formed in a tab shape (rectangular shape) and extends from the cathode body 22a to the other side S2 in the Z direction. The two cathode junctions 22b are respectively arranged at a pair of corners located diagonally in the cathode junction 22b.

The anode current conductor 23 is a rod-shaped pin (stem pin) that is provided so as to penetrate the stem portion 11 and is fixed to the stem portion 11. The anode current conductor 23 is joined to the anode joint portion 21b, for example, by welding, and extends straight from the anode joint portion 21b in the Z direction to the outside of the container 10. The anode current conductor 23 is formed, for example, from Kovar metal.

The cathode current conductor 24 is a rod-shaped pin (stem pin) that is provided to penetrate the stem portion 11 and is fixed to the stem portion 11. The cathode current conductor 24 is joined to the cathode joint portion 22b, for example, by welding, and extends straight from the cathode joint portion 22b along the Z direction to the outside of the container 10. The cathode current conductor 24 is formed, for example, from Kovar metal. In this example, when viewed from the Z direction, the two anode current conductors 23 face each other across the center of the ultraviolet detection tube 2, and the two cathode current conductors 24 face each other across the center of the ultraviolet detection tube 2.

When the ultraviolet detection tube 2 is in use, a voltage is applied between the anode 21 and the cathode 22 via the anode current conductor 23 and the cathode current conductor 24. When ultraviolet light is incident on the cathode 22 (surface 22c) through the container 10 (valve section 12) and the hole 21c of the anode 21 in use, photoelectrons are emitted from the cathode 22. These photoelectrons are attracted to the anode 21 and collide with the discharge gas molecules in the container 10, ionizing the discharge gas molecules. Of the electrons and positive ions generated by the ionization, the electrons further collide with other discharge gas molecules and ionize them, reaching the anode 21. Meanwhile, the positive ions are accelerated toward the cathode 22, collide with the cathode 22, and generate many secondary electrons. By repeating the above phenomenon, a current flows between the anode 21 and the cathode 22, resulting in a discharge state. The ultraviolet detection tube 2 uses this discharge phenomenon to detect ultraviolet light.

The circuit board 3 is, for example, a rectangular flat printed circuit board (PCB) and is arranged perpendicular to the Z direction. The circuit board 3 is fixed to the housing 4 using, for example, fastening members 3a. In this example, a cylindrical spacer member 3b is arranged between the circuit board 3 and the housing 4, and the circuit board 3 is arranged at a predetermined distance from the bottom wall 4b of the housing 4 in the Z direction.

Various electronic components 31 are mounted on the circuit board 3. The electronic components 31 include, for example, electronic components that constitute a drive circuit 32 (drive unit) for driving the ultraviolet detection tube 2. The electronic components 31 may also include a microcomputer that controls each element, a reading circuit that reads the output signal from the ultraviolet detection tube 2, a DC-DC converter, and the like. The microcomputer constitutes the determination unit 60, which will be described later. Note that, although two electronic components 31 are shown in simplified form as an example in Figures 2 and 3, in reality, many electronic components are mounted on the circuit board 3.

The ultraviolet detection tube 2 is mounted on the circuit board 3. The circuit board 3 is provided with four sockets 33 for holding (fixing) the anode current conductor 23 or the cathode current conductor 24. The anode current conductor 23 and the cathode current conductor 24 are inserted and held in these sockets 33, respectively, thereby holding the ultraviolet detection tube 2 on the circuit board 3. In this way, the ultraviolet detection tube 2 is held (fixed) on the circuit board 3 at the anode current conductor 23 and the cathode current conductor 24 on the other side S2 in the Z direction. As shown in FIG. 3, a gap S is provided in the Z direction between the stem portion 11 of the container 10 (the part of the other side S2 of the container 10) and the circuit board 3. In other words, the stem portion 11 of the container 10 is arranged to be separated from the circuit board 3 with a gap S.

The socket 33 has a contact portion made of, for example, a leaf spring, and is configured so that when the pin-shaped anode current-carrying portion 23 or cathode current-carrying portion 24 is inserted, the contact portion elastically contacts the anode current-carrying portion 23 or cathode current-carrying portion 24. As a result, the socket 33 holds the anode current-carrying portion 23 or cathode current-carrying portion 24 by sandwiching them. In this example, the anode current-carrying portion 23 or cathode current-carrying portion 24 is not completely fixed to the circuit board 3 through the socket 33, as in the case of fixing by soldering, for example. Under normal conditions, a certain fixed state is maintained, but the anode current-carrying portion 23 or cathode current-carrying portion 24 is elastically held so that the fixed state relative to the circuit board 3 can be slightly changed (so that the anode current-carrying portion 23 or cathode current-carrying portion 24 can be slightly moved relative to the circuit board 3) when stress is applied to the ultraviolet detection tube 2 due to vibration or impact on the ultraviolet detection device 1. Therefore, compared to when the pin-shaped anode current-carrying part 23 or the cathode current-carrying part 24 is completely fixed to the circuit board 3, it is possible to reduce the possibility that the ultraviolet detection tube 2 itself will be damaged when stress is applied to the ultraviolet detection tube 2 due to vibration or impact on the ultraviolet detection device 1, for example. The ultraviolet detection tube 2 is removable from the socket 33 and can be replaced.

A first light-emitting element 5 and a second light-emitting element 6 are further mounted on the circuit board 3. The first light-emitting element 5 and the second light-emitting element 6 are arranged so as to be adjacent to the ultraviolet detection tube 2 in the Y direction (direction perpendicular to the Z direction). The first light-emitting element 5 and the second light-emitting element 6 are semiconductor light-emitting elements such as LEDs (Light Emitting Diodes). The first light-emitting element 5 outputs ultraviolet light having a wavelength included in the sensitivity wavelength range of the ultraviolet detection tube 2 as the first light L1. The second light-emitting element 6 outputs ultraviolet light having a wavelength longer than the first light L1 output by the first light-emitting element 5 as the second light L2. As an example, the wavelength of the first light L1 is 275 nm, and the wavelength of the second light L2 is 365 nm. The first light-emitting element 5 and the second light-emitting element 6 are arranged so as to output the first light L1 and the second light L2 toward one side S1 in the Z direction. That is, the light emission surfaces of the first light-emitting element 5 and the second light-emitting element 6 face the one side S1.

The housing 4 is formed in a box shape from a metal material such as aluminum. The housing 4 houses the ultraviolet detection tube 2 and the circuit board 3. The housing 4 has a light introduction section 41 through which the light LT incident on the ultraviolet detection tube 2 is introduced. In this example, the light introduction section 41 is configured by attaching a unit 42 to an opening 4c formed in the top wall 4a of the housing 4. The top wall 4a is, for example, a lid portion configured to be removable from other parts of the housing 4. The unit 42 includes a first member 51, a second member 52, a window member 53, an O-ring 54, an O-ring 55, and an O-ring (elastic member) 56. The unit 42 constitutes a part of the housing 4. In FIG. 2, the top wall 4a and the first member 51 are omitted.

The first member 51 has a cylindrical portion 51a and an annular flange portion 51b extending radially outward from the end of the cylindrical portion 51a on the other side S2 in the Z direction. An O-ring 56 is attached to the inside of the cylindrical portion 51a. The O-ring 56 will be described later. The second member 52 has a cylindrical portion 52a, a cylindrical portion 52b located on one side S1 in the Z direction relative to the cylindrical portion 52a, and an annular connection portion 52c formed between the cylindrical portions 52a and 52b. The inner diameter of the cylindrical portion 52a is approximately the same as the inner diameter of the cylindrical portion 51a, and the inner diameter of the cylindrical portion 52b is larger than the inner diameter of the cylindrical portion 52a. The first member 51 and the second member 52 are formed of a metal material such as aluminum.

The first member 51 is disposed so that the cylindrical portion 51a is located within the opening 4c and the flange portion 51b faces the top wall 4a within the housing 4, and is fixed to the top wall 4a at the flange portion 51b. The flange portion 51b is fixed to the top wall 4a by a fastening member such as a screw (not shown). The second member 52 is fixed to the cylindrical portion 51a of the first member 51 at the cylindrical portion 52a by a fastening member such as a screw (not shown).

The window member 53 is disposed between the cylindrical portion 52a of the second member 52 and the cylindrical portion 51a of the first member 51. The window member 53 is formed, for example, in a flat plate shape from glass and has optical transparency to ultraviolet light. The window member 53 contributes to the stable operation of the ultraviolet detection device 1 by suppressing the intrusion of foreign matter from the light introduction portion 41 into the space in which the ultraviolet detection tube 2 and the circuit board 3 are housed and by blocking heat from the light introduction portion 41. An O-ring 54, which mainly functions as a sealing member, is interposed between the window member 53 and the cylindrical portion 52a. The O-ring 54 seals the gap between the window member 53 and the cylindrical portion 52a, and can suppress the intrusion of foreign matter from the light introduction portion 41 into the space in which the ultraviolet detection tube 2 and the circuit board 3 are housed, for example. The O-ring 54 also has a function of relieving stress on the window member 53. In addition, an O-ring 55, which mainly functions as a sealing member, is disposed on the connection portion 52c of the second member 52. The O-rings 54 and 55 are primarily used to seal between adjacent components and are formed into an annular shape from an elastic material such as rubber or a resin material such as urethane.

A thread groove is formed on the inner surface of the cylindrical portion 52b of the second member 52 for attachment to an attachment target. The attachment target is, for example, a detection window portion provided in a boiler. For example, the second member 52 (ultraviolet light detection device 1) is attached to the detection window portion by screwing the thread formed on the detection window portion into the thread groove on the inner surface of the cylindrical portion 52b. At this time, the above-mentioned O-ring 55 is interposed between the detection window portion and the second member 52, sealing the gap between the detection window portion and the second member 52. The inner surface of the cylindrical portion 52b may be processed to increase the light reflectance so as to make it easier to capture the light LT arriving from the detection window portion.

Light LT coming from the boiler detection window is introduced through the second member 52 and enters the window member 53. The window member 53 transmits ultraviolet light from the incident light LT. The light LT that passes through the window member 53 is introduced into the housing 4 via the first member 51 and the opening 4c, and enters the ultraviolet detection tube 2. As a result, the light LT from the boiler detection window, i.e., the ultraviolet light contained in the boiler flame, is detected by the ultraviolet detection tube 2. In this way, the ultraviolet detection tube 2 can function as a flame sensor.

At one side S1 in the Z direction, the ultraviolet detection tube 2 is held (fixed) to the housing 4 at the valve portion 12 (the portion of the ultraviolet detection tube 2 at one side S1). More specifically, the valve portion 12 is pressed against the inner surface of the cylindrical portion 51a of the first member 51 with the O-ring 56 interposed therebetween, so that the valve portion 12 is held to the top wall 4a of the housing 4 at one side S1 in the Z direction. This prevents the ultraviolet detection tube 2 from swinging, for example, in the X direction or Y direction, at one side S1 in the Z direction due to vibration or impact on the ultraviolet detection device 1. Furthermore, the top wall 4a of the housing 4 presses the valve portion 12 against the circuit board 3 via the O-ring 56. In other words, the ultraviolet detection tube 2 is fixed so as to be sandwiched between the top wall 4a of the housing 4 and the circuit board 3. This also prevents swinging in the Z direction. Thus, in this example, the valve portion 12 is held to the housing 4 at the light introduction portion 41.

Such holding can be achieved, for example, by bringing the unit 42 closer from one side S1 in the Z direction to the ultraviolet detection tube 2 held on the circuit board 3 at the other side S2 in the Z direction. In this case, for example, the top wall 4a to which the unit 42 is fixed is brought closer to the bottom wall 4b of the housing 4 to which the circuit board 3 is fixed. This holds the ultraviolet detection tube 2 on both the one side S1 and the other side S2 in the Z direction, and as a result, the ultraviolet detection tube 2 is held within the housing 4. In this example, the ultraviolet detection tube 2 is positioned so that the curved portion 14 (the portion on one side S1 in the Z direction) faces the light introduction section 41 of the housing 4.

The O-ring 56 is an elastic member provided mainly to relieve stress on the valve part 12 by being sandwiched between the valve part 12 and the first member 51, and is formed in a circular shape from an elastic material made of a resin material such as rubber or urethane. Therefore, by utilizing the elasticity of the O-ring 56, it is possible to both fix the ultraviolet detection tube 2 and suppress damage to the ultraviolet detection tube 2 by relaxing the stress between the ultraviolet detection tube 2 and the first member 51 associated with the fixation. In other words, according to this configuration, the ultraviolet detection tube 2 can be fixed to the housing 4 reliably by the O-ring 56 and the socket 33 while relaxing the stress. In addition, the O-ring 56 also functions as a sealing member that seals between the valve part 12 and the first member 51, and can suppress the intrusion of foreign matter from the light introduction part 41 into the space in which the ultraviolet detection tube 2 and the circuit board 3 are housed. The O-ring 56 has, for example, a circular cross section. The O-ring 56 is formed of, for example, silicone rubber. The rigidity of the O-ring 56 is lower than the rigidity of the container 10. That is, the O-ring 56 is softer than the container 10.

The O-ring 56 is arranged so as not to overlap the anode 21 and the cathode 22 when viewed from the Z direction. In other words, the O-ring 56 is located outside the anode 21 and the cathode 22 when viewed from the Z direction. The O-ring 56 is in contact with the curved portion 14 of the valve portion 12. In this example, the O-ring 56 is in contact with the outer edge of the curved portion 14 so as to overlap the edge of the cylindrical portion 13 when viewed from the Z direction. In the Z direction, the entire O-ring 56 is located on one side S1 relative to the anode 21 and the cathode 22.

The following describes how to check the operation of the ultraviolet detection device 1. The ultraviolet detection device 1 is equipped with a judgment unit 60 that judges the operating state of the ultraviolet detection tube 2. The judgment unit 60 is configured, for example, by a microcomputer that is one of the electronic components 31 mounted on the circuit board 3 described above.

During operation check, the judgment unit 60 causes the first light-emitting element 5 to output (drive) the first light L1 and causes the second light-emitting element 6 to output (drive) the second light L2. The judgment unit 60 reads the output signal from the ultraviolet detection tube 2 via the reading circuit, and judges the driving state of the ultraviolet detection tube 2 based on the signal of the ultraviolet detection tube 2 accompanying the driving of the first light-emitting element 5 and the second light-emitting element 6. This judgment is performed, for example, when the power of the ultraviolet detection device 1 is turned on. A further judgment may be performed at any timing after the power is turned on. The judgment result is output to the outside by any means or notified to the user.

For example, when the ultraviolet detection tube 2 reacts to the first light L1 but does not react to the second light L2, the judgment unit 60 judges that the ultraviolet detection tube 2 is operating normally. In this case, the ultraviolet detection tube 2 is sensitive to the target wavelength (275 nm) but is not sensitive to a longer wavelength (365 nm). On the other hand, when the ultraviolet detection tube 2 does not react to the first light L1 and the second light L2, the judgment unit 60 judges that a malfunction has occurred in the ultraviolet detection tube 2. In addition, the judgment unit 60 also judges that a malfunction has occurred in the ultraviolet detection tube 2 when the ultraviolet detection tube 2 reacts to the first light L1 and the second light L2. In this case, the ultraviolet detection tube 2 is sensitive not only to the target wavelength (275 nm) but also to a longer wavelength (365 nm). Such malfunctions can occur, for example, due to aging.

The first light L1 and the second light L2 output from the first light-emitting element 5 and the second light-emitting element 6 are, for example, reflected by the flange portion 51b of the first member 51 and enter the bulb portion 12 of the ultraviolet detection tube 2. Therefore, in the ultraviolet detection device 1, the surface 51c of the other side S2 in the Z direction of the flange portion 51b is configured to have a higher light reflectance than other parts of the housing 4. The surface 51c is a part of the housing 4 located between the ultraviolet detection tube 2 and the first light-emitting element 5 and the second light-emitting element 6 when viewed from the Z direction, and is a part where the first light L1 and the second light L2 from the first light-emitting element 5 and the second light-emitting element 6 are reflected toward the ultraviolet detection tube 2. For example, the surface 51c may be processed to increase the light reflectance. In addition, the light output from the first light-emitting element 5 and the second light-emitting element 6 can also enter the bulb portion 12 of the ultraviolet detection tube 2 by repeatedly reflecting and scattering within the housing 4.
[Action and Effects]

In the ultraviolet detection device 1, the ultraviolet detection tube 2 is held by the housing 4 on one side S1 in the Z direction, and is held by the circuit board 3 at the anode current conductor 23 or the cathode current conductor 24 on the other side S2 in the Z direction. This allows the ultraviolet detection tube 2 to be securely held by the housing 4 on one side S1 in the Z direction, and the ultraviolet detection tube 2 can be securely held by the circuit board 3 fixed to the housing 4 on the other side S2 in the Z direction. In this way, by holding the ultraviolet detection tube 2 on both the one side S1 and the other side S2 in the Z direction, it is possible to effectively increase resistance to vibration and impact. Therefore, according to the ultraviolet detection device 1, it is possible to improve resistance to vibration or impact (earthquake resistance). Such improvement in resistance to vibration or impact is particularly effective when the ultraviolet detection device 1 is used to monitor a boiler, for example. This is because vibrations are likely to occur when the boiler is in operation. In addition, improvement in resistance to vibration or impact is also important from the viewpoint of suppressing the occurrence of malfunctions due to the ultraviolet detection device 1 being dropped during transportation or handling.

An O-ring 56 (elastic member) is interposed between the valve portion 12 (the portion on one side S1 in the Z direction of the ultraviolet detection tube 2) and the housing 4. This further improves resistance to vibration and impact.

The O-ring 56 is positioned so that it does not overlap the anode 21 and the cathode 22 when viewed from the Z direction. This prevents the O-ring 56 from blocking the light LT incident on the anode 21 and the cathode 22, thereby preventing a decrease in sensitivity.

The O-ring 56 is in contact with the curved portion 14 of the container 10. This allows the UV detection tube 2 to be held more firmly than, for example, when the O-ring 56 is in contact with the side of the cylindrical portion 13 of the container 10.

The O-ring 56 is positioned so that it overlaps the edge of the cylindrical portion 13 when viewed from the Z direction. This makes it possible to firmly hold the ultraviolet detection tube 2 while preventing the O-ring 56 from blocking light incident on the anode 21 and cathode 22, which would otherwise reduce sensitivity.

A gap S is provided between the stem portion 11 (the portion on the other side S2 of the container 10 in the Z direction) and the circuit board 3. This prevents the container 10 from coming into contact with the circuit board 3 and being damaged by vibration or impact.

The ultraviolet detection tube 2 is arranged so that one side S1 in the Z direction faces the light introduction section 41 of the housing 4. This allows the ultraviolet detection tube 2 to be arranged with suitable directivity.

The ultraviolet detection device 1 includes a first light-emitting element 5 that outputs ultraviolet light (first light L1) having a wavelength included in the sensitivity wavelength range of the ultraviolet detection tube 2, and the first light-emitting element 5 is a semiconductor light-emitting element. This makes it possible to accurately check the operation of the ultraviolet detection tube 2. That is, the target wavelength can be obtained more reliably than when a discharge tube is used as the light-emitting element. More specifically, for example, when a hydrogen discharge tube is placed instead of the first light-emitting element 5 and the operating state of the ultraviolet detection tube 2 is determined based on the detection result of the light from the hydrogen discharge tube, the light from the hydrogen discharge tube also contains light in the infrared range, so the solar blind characteristics of the ultraviolet detection tube 2 cannot be confirmed. In contrast, in the ultraviolet detection device 1, by using the first light-emitting element 5, which is a semiconductor light-emitting element, the ultraviolet detection tube 2 can detect the target light (ultraviolet light), and the operation of the ultraviolet detection tube 2 can be accurately checked.

The ultraviolet detection device 1 is provided with a determination unit 60 that is provided on the circuit board 3 and determines the operating state of the ultraviolet detection tube 2 based on the output signal of the ultraviolet detection tube 2 accompanying the operation of the first light-emitting element 5. This allows the operating reliability of the ultraviolet detection device 1 to be improved by determining the operating state, including checking the operation of the ultraviolet detection tube 2. More specifically, for example, the operating state of the ultraviolet detection tube 2 can change depending on the wavelength and light amount of the incident ultraviolet light, but by using a semiconductor light-emitting element as the first light-emitting element 5, ultraviolet light with a stable wavelength and light amount can be output, making it possible to check the operating state under certain conditions.

The ultraviolet detection device 1 is equipped with a second light-emitting element 6 that outputs light (second light L2) having a longer wavelength than the ultraviolet light output by the first light-emitting element 5, and the judgment unit 60 judges the operating state of the ultraviolet detection tube 2 based on the output signal of the ultraviolet detection tube 2 accompanying the operation of the first light-emitting element 5 and the output signal of the ultraviolet detection tube 2 accompanying the operation of the second light-emitting element 6. In this case, as described above, it is possible to grasp the occurrence of a malfunction that causes the ultraviolet detection tube 2 to react to light in a wavelength range longer than the target wavelength range (ultraviolet region) due to aging or the like.

The O-ring 56 is located on one side S1 in the Z direction relative to the anode 21 and the cathode 22. This prevents the light from the first light-emitting element 5 from being blocked by the O-ring 56, making it easier for the light from the first light-emitting element 5 to enter the anode 21 and the cathode 22.

The first light-emitting element 5 and the second light-emitting element 6 are arranged on the circuit board 3 so as to output ultraviolet light (first light L1 and second light L2) toward one side S1 in the Z direction, and the surface 51c of the flange portion 51b (the portion of the housing 4 located between the ultraviolet detection tube 2 and the first light-emitting element 5 when viewed from the Z direction) has a higher light reflectance than other parts of the housing 4. As a result, by fixing the first light-emitting element 5 and the second light-emitting element 6 to the circuit board 3 in a stable state, the resistance to vibration and impact is improved, and the light from the first light-emitting element 5 and the second light-emitting element 6 is reflected by the surface 51c of the flange portion 51b and easily enters the ultraviolet detection tube 2.

The present invention is not limited to the above embodiment. For example, the material and shape of each component are not limited to the above-mentioned material and shape, and various materials and shapes can be adopted. In the above embodiment, the anode body 21a and the cathode body 22a are flat, but the anode body 21a and the cathode body 22a (anode 21 and cathode 22) may be rod-shaped or a combination of rod and plate shapes. The anode current conductor 23 and the anode 21 may be integrally formed, and the cathode current conductor 24 and the cathode 22 may be integrally formed. The number of anode current conductors 23 may be one, or three or more. The number of cathode current conductors 24 may be one, or three or more. In the above embodiment, the anode current conductors 23 and the cathode current conductors 24 were not completely fixed by using the socket 33, but the anode current conductors 23 and the cathode current conductors 24 may be completely fixed to the circuit board 3 by soldering or the like.

In this embodiment, the O-ring 56, which is a circular elastic member, is used, but the elastic member may be a polygonal elastic member or a linear elastic member wound around it, or a plurality of divided elastic members arranged at desired positions, or an elastic material applied and solidified at desired positions. The O-ring 56 may have a portion that overlaps with the anode 21 and the cathode 22 when viewed from the Z direction. The O-ring 56 may be in contact with the side surface of the cylindrical portion 13 of the container 10. The O-ring 56 may be located on the other side S2 in the Z direction relative to the anode 21 and the cathode 22. The O-ring 56 may be omitted, and for example, the valve portion 12 may be in direct contact with the first member 51. The means for holding the ultraviolet detection tube 2 on the circuit board 3 is not limited to the socket 33, and may be any holding means. The ultraviolet detection tube 2 may be held in a state in which the stem portion 11 is in contact with the circuit board 3.

The second light-emitting element 6 may be omitted, and only the first light-emitting element 5 may be provided. In this case, the judgment unit 60 judges the driving state of the ultraviolet light detection tube 2 based on the output signal of the ultraviolet light detection tube 2 accompanying the driving of the first light-emitting element 5. Both the first light-emitting element 5 and the second light-emitting element 6 may be omitted. The surface 51c of the flange portion 51b does not need to have a high light reflectance compared to other parts of the housing 4, and for example, the entire inner surface of the housing 4 may have the same light reflectance.

In the above embodiment, one side S1 in the Z direction of the ultraviolet detection tube 2 faces the light introduction part 41 of the housing 4, but the arrangement of the ultraviolet detection tube 2 is not limited to this. For example, if the anode body part 21a and the cathode body part 22a are rod-shaped, light may be incident on the ultraviolet detection tube 2 from the side. In the above embodiment, the ultraviolet detection tube 2 is held in the housing 4 at the light introduction part 41, but the ultraviolet detection tube 2 may be held in the housing 4 at a position other than the light introduction part 41.

1...UV detector, 2...UV detector tube, 3...circuit board, 4...housing, 5...first light-emitting element, 6...second light-emitting element, 10...container, 13...cylindrical portion, 14...curved portion, 21...anode (electrode), 22...cathode (electrode), 23...anode current-carrying portion, 24...cathode current-carrying portion, 32...drive circuit, 41...light introduction portion, 56...O-ring, 60...determination portion, G...discharge gas, LT...light, S...gap, S1...one side, S2...other side.

Claims (12)

an ultraviolet detection tube including a vessel filled with a discharge gas, a pair of electrodes disposed within the vessel, and at least two conductive parts electrically connected to the pair of electrodes, respectively, and extending to the outside of the vessel along a predetermined direction;
a circuit board provided with a drive circuit for driving the ultraviolet detection tube;
a housing that houses the ultraviolet detection tube and the circuit board and has a light introduction section through which light incident on the ultraviolet detection tube is introduced;
The circuit board is fixed to the housing,
an ultraviolet detection device, the ultraviolet detection tube being held by the housing on one side in the predetermined direction, and being held by the circuit board at the current-carrying portion on the other side in the predetermined direction; The ultraviolet detection device according to claim 1, wherein an elastic member is interposed between the housing and a portion of the ultraviolet detection tube on one side in the predetermined direction. The ultraviolet detection device according to claim 2, wherein the elastic member is arranged so as not to overlap the pair of electrodes when viewed from the predetermined direction. the container has a cylindrical portion having a center line along the predetermined direction, and a curved portion that is disposed on one side of the cylindrical portion in the predetermined direction and is curved so as to be convex toward the one side,
4. The ultraviolet detection device according to claim 2, wherein the elastic member is in contact with the curved portion. the container has a cylindrical portion having a centerline along the predetermined direction,
4. The ultraviolet detection device according to claim 2, wherein the elastic member is disposed so as to overlap an edge of the cylindrical portion when viewed from the predetermined direction. The ultraviolet detection device according to claim 1 or 2, wherein a gap is provided between the other side of the container in the predetermined direction and the circuit board. The ultraviolet detection device according to claim 1 or 2, wherein the ultraviolet detection tube is arranged so that a portion on one side in the predetermined direction faces the light introduction part of the housing. a first light emitting element that outputs ultraviolet light having a wavelength included in the sensitivity wavelength range of the ultraviolet detection tube;
The ultraviolet detection device according to claim 1 , wherein the first light emitting element is a semiconductor light emitting element. The ultraviolet detection device according to claim 8, further comprising a determination unit provided on the circuit board for determining the operating state of the ultraviolet detection tube based on an output signal of the ultraviolet detection tube accompanying the operation of the first light emitting element. a second light-emitting element that outputs light having a longer wavelength than the ultraviolet light output by the first light-emitting element;
The ultraviolet detection device according to claim 9 , wherein the determination unit determines the drive state of the ultraviolet detection tube based on an output signal of the ultraviolet detection tube accompanying the drive of the first light-emitting element and an output signal of the ultraviolet detection tube accompanying the drive of the second light-emitting element. an elastic member is interposed between the housing and a portion of the ultraviolet detection tube on one side in the predetermined direction;
9. The ultraviolet ray detecting device according to claim 8, wherein the elastic member is located on one side of the pair of electrodes in the predetermined direction. the first light-emitting element is disposed on the circuit board so as to output the ultraviolet light toward one side of the predetermined direction;
9. The ultraviolet detection device according to claim 8, wherein a portion of the housing located between the ultraviolet detection tube and the first light-emitting element when viewed from the predetermined direction has a higher light reflectance than other portions of the housing.

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