JP6066799B2 - Flame detection sensor - Google Patents

Description

The present invention relates to an ultraviolet ray detection unit of a flame detection sensor that detects ultraviolet rays contained in a flame of a combustion apparatus.

There is a UV tube as a flame detection sensor that detects and monitors the flame in the combustion device by detecting the ultraviolet rays contained in the flame and ensures combustion safety.
The UV detection unit installed inside the UV tube is a pair of metallic discharge electrodes that generate a discharge upon receiving UV light, and the lead wires of the pair of discharge electrodes are the glass tubes of the UV tube. Derived from one end (see, for example, Patent Document 1).
FIG. 1 is a schematic diagram showing the structure of a conventional UV tube. A mesh-like anode electrode 11 and a cathode electrode 12 are supported by lead wires 13 and 14 in a glass tube 10 in which gas is sealed. The anode electrode 11 and the cathode electrode 12 have a parallel plate structure, and are arranged with a distance of about 0.5 mm between the electrodes. The ultraviolet rays incident from the end of the glass tube 10 (the upper end in FIG. 1) pass through the mesh of the anode electrode 11 and hit the cathode electrode 12 to emit secondary electrons and avalanche phenomenon of the secondary electrons. As a result, discharge occurs. Since the UV tube has a specific discharge performance, an arbitrary component specific gas is sealed inside the UV tube.

The invention in Patent Document 2 by the present applicant and the same applicant is an integrated flame detection sensor made of a glass material having a pair of metal electrodes. FIG. 2A in the present application is a cross-sectional view showing components of the flame detection sensor. A glass plate 21 having ultraviolet transparency and a glass plate 22 having a concave structure are components of the flame detection sensor.
In the concave portions of the glass plate 21 and the glass plate 22, an anode electrode 24 and a cathode electrode 28 on which metal is deposited are formed. Since the ultraviolet rays can pass through the glass plate 21 and reach the cathode electrode 28, the anode electrode 24 is formed as an electrode having a mesh pattern. Conductor portions 25 and 29 are provided to apply an arbitrary voltage to each electrode from the outside of the flame detection sensor. FIG. 2B is a cross-sectional view showing the flame detection sensor in which the components shown in FIG. A space formed by the concave portions of the glass plate 21 and the glass plate 22 corresponds to an ultraviolet ray detection part of a conventional UV tube, and discharges between the electrodes when the ultraviolet ray hits. The detection of the discharge phenomenon generated in the electrode due to the irradiation of the ultraviolet rays contained in the flame is made by observing the change in voltage or current between the electrodes 24 and 25. Similar to the UV tube of Patent Document 1, a specific gas of an arbitrary component is sealed inside the UV tube to have a specific discharge performance.

Japanese Patent Publication No. 44-1039 JP 2013-19719 A

In the invention of Patent Document 1, since it is not easy to heat the lead wire at the same length and the same temperature when melting the electrode end by laser welding, the electrode plate placed on the lead wire may be inclined as a result. There is.
Since the electrode plate does not become flat, the distance and electric field between the two electrodes are different from the central part and the periphery of the electrode. As a result, the electric field distribution between the electrodes is not flat. In this way, when the electric field distribution is biased, a discharge may occur in a region where the electric field strength is large even if ultraviolet rays do not hit. Further, in a region where the electric field strength is low, there is a case where no discharge occurs even when the ultraviolet ray hits. When such a discharge abnormality occurs, it becomes difficult to detect ultraviolet rays accurately, and there arises a problem that the combustion detection of the combustion apparatus does not work normally.

  Patent Document 2 is an invention made to realize a UV tube that is small in size and that does not cause distortion by making the electrodes parallel to each other. In order to generate a discharge between the electrodes during ultraviolet irradiation, a specific gas is sealed in the internal space of the UV tube as in the conventional UV tube. For this reason, it is necessary to introduce a production facility equipped with a gas chamber and a gas pressure control device, which requires cost and labor when introducing the production facility and operating the facility.

The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide an ultraviolet detector for a UV tube having a high degree of parallelism that does not cause distortion in an electrode plate.

In order to achieve the above object, the present invention provides an Si base having a hole penetrating ultraviolet rays, electrically insulated from an upper lid on which an inner surface of the Si base is vapor-deposited with metal to form an anode electrode. The cylindrical glass of the body and the Si base machined into the shape of the recess, and the electrode part integrated by joining the lower lid on which the inner surface of the recess was vapor-deposited with metal to form the cathode electrode The present invention provides a UV tube having an ultraviolet detection part characterized by the above. Since the upper cover S has penetrated ultraviolet rays, the anode electrode is a metal plane having a mesh pattern. On the other hand, the cathode electrode was a metal plane without holes. Furthermore, by creating an electrode terminal portion connected via a conductive material to the surface of the anode electrode and the cathode electrode on the opposite side of the Si substrate, the anode electrode and the cathode electrode are connected to the anode electrode and the cathode electrode from the outside of the UV tube. Arbitrary voltage can be applied. The UV detector replaces a pair of conventional metal electrodes of a conventional UV tube.

  The present invention can manufacture an ultraviolet detection unit including an anode electrode and a cathode electrode which are parallel to each other without distortion.

It is a schematic diagram which shows the structure of the conventional type UV tube which is a flame detection sensor. It is a schematic diagram which shows the structure of the UV tube of patent document 2. FIG. (A) is sectional drawing of an anode electrode part and a cathode electrode part, (b) is sectional drawing of UV tube. It is a figure explaining the component (anode electrode part) of the ultraviolet-ray detection part of Embodiment 1 of this invention which concerns on Embodiment 2, and the UV tube. It is a figure explaining the component (cathode electrode part) of the ultraviolet-ray detection part of Embodiment 1 of this invention and the UV tube which concerns on Embodiment 2. FIG. It is a schematic diagram which shows the ultraviolet-ray detection part of the UV tube which concerns on Embodiment 1 of this invention. It is a schematic diagram which shows the ultraviolet-ray detection part of the UV tube which concerns on Embodiment 2 of this invention.

  Embodiments of the present invention will be described below.

The first embodiment of the present invention will be described in detail with reference to FIGS. 3, 4 and 5. FIG.
Embodiment 1 FIG.

FIG. 3A is a plan view of the upper lid 31 provided with an anode electrode placed opposite to the entire UV tube or a part of the UV tube that transmits ultraviolet rays. FIG. 3B is a cross-sectional view of the upper lid 31. The upper lid 31 is a Si substrate. A hole is made so that the ultraviolet rays pass through the Si substrate and reach the cathode electrode 42 of the lower lid 41. This hole is created by dry etching or wet etching process technology. After removing the Si oxide film on the surface layer of the Si substrate, W (tungsten) is deposited to make the anode electrode 32. After deposition, the surface of the Si substrate except the W (tungsten) surface is covered with an oxide Si film having an arbitrary thickness. Since the Si substrate is perforated, the anode electrode 32 has a mesh pattern. In the upper lid 31, the outer peripheral portion 33 is a place where the W (tungsten) is not deposited. Although not shown in the drawing, an electrode terminal portion is provided on the surface of the Si base of the upper lid 31 opposite to the anode electrode 32, and the electrode terminal is connected to the anode electrode 32 via the conductor portion. . The electrode terminal portion is connected to a lead wire extending outside the UV tube. The cathode electrode portion 41 is located in the direction A shown in FIG.

FIG. 4A and FIG. 4B are views showing a lower lid 41 provided with the cathode electrode portion 42. 4A is a plan view of the lower lid 41, and FIG. 4B is a sectional view thereof. The lower lid 41 is a Si base. The lower lid 41 is pierced in the shape of a recess at the center. In order to form the recess structure, dry etching or wet etching process technology is adopted for the central portion of the Si substrate. The central portion may be shaved by physical polishing to form a concave shape. During the production of the recess, the Si oxide film on the surface layer of the recess is removed. In the next step, W (tungsten) is deposited on the bottom surface of the recess to form the cathode electrode 42. After deposition, the surface of the Si substrate except the W (tungsten) surface is covered with an oxide Si film having an arbitrary thickness. The cathode electrode 42 has a pattern without holes. In the lower lid 41, 43 is a place where the W (tungsten) is not deposited in the periphery of the recess. Although not shown in the figure, an electrode terminal portion is provided on the surface of the Si base of the lower lid 41 opposite to the cathode electrode 42, and the electrode terminal portion is connected to the cathode electrode 42 via a conductor portion. . The electrode terminal portion is connected to a lead wire extending outside the UV tube.
The anode electrode part is joined from the A direction shown in FIG.

The reason why Si is used for the material of the upper lid 31 with the anode electrode 32 and the material of the lower lid 41 with the cathode electrode 42 is established in the semiconductor industry because it is inexpensive and readily available. This is because the Si microfabrication technology can be used.

FIG. 5A is a cross-sectional view showing an ultraviolet detection unit in which the upper lid 31 in FIG. 3A and the lower lid 41 in FIG. 4A are joined together by direct joining . FIG. 5B is a side view of the ultraviolet detection unit.

The outer peripheral portion 33 of the upper lid 31 and the peripheral portion 43 of the concave portion of the lower lid 41 are mechanically polished to remove the Si oxide film and smooth the surface so that the anode electrode 32 and the cathode electrode 42 are parallel to each other. To process. In the next step, the upper lid 31 and the lower lid 41 are directly joined.

The assembled ultraviolet detection part is replaced with a pair of metal electrode plates constituting the conventional ultraviolet detection part of the UV tube shown by 11 and 12 in FIG.

The second embodiment of the present invention will be described in detail with reference to FIGS. 3, 4 and 6. FIG.
Embodiment 2. FIG.

FIG. 6 (a) shows an ultraviolet ray in which the upper lid 31 of FIG. 3 (a) and the lower lid 41 of FIG. 4 (a) are joined together by anodic bonding with a cylindrical glass 51 for insulation interposed therebetween. It is a side view of a detection part, FIG.6 (b) is sectional drawing.

The outer peripheral portion 33 of the upper lid 31 and the peripheral portion 43 of the concave portion of the lower lid 41 are places where the insulating cylindrical glass 51 is joined. In this part, the oxidized Si film is removed by mechanical polishing and the surface is processed smoothly. At the same time, the peripheral portion of the concave portion is polished so that the peripheral portion of the concave portion and the cathode electrode 42 are parallel to each other. Further, the upper and lower joint portions of the cylindrical glass are also polished so that the surfaces thereof are smooth and the planes serving as the joint portions are parallel to each other. As a result, the surface can be closely adhered without gaps during anodic bonding, and the parallelism between the anode electrode 32 and the cathode electrode 42 is kept high.

Thereafter, except for the surface of the W (tungsten) electrode, the surface of the ultraviolet detection portion is covered with a film of Si oxide having an arbitrary thickness.

The assembled ultraviolet detection part is replaced with a pair of metal electrode plates constituting the conventional ultraviolet detection part of the UV tube shown by 11 and 12 in FIG.

The upper lid 31 and the cylindrical glass 51 are joined by the anodic bonding technique, and the cylindrical glass 51 and the lower lid 41 are joined. However, they may be joined directly or using an adhesive.

In the present invention, W (tungsten) is vapor-deposited on two Si substrates without adopting a method of maintaining the parallelism of electrodes by joining a lead wire and an electrode plate by laser welding as in the conventional UV tube manufacturing method. Therefore, the two electrodes can be manufactured with a high degree of parallelism.

Since the internal space of the UV tube of the present invention is larger than the internal space of the UV tube of Patent Document 2, even if there is a change in discharge characteristics due to the specific gas leakage, there is little influence on the ultraviolet detection performance.

When depositing the W (tungsten) on the ultraviolet detection section, the surface of the Si substrate may be deposited with a Si oxide film attached thereto. However, the W (tungsten) surface after vapor deposition remains a metal and is not covered with an insulator such as an Si oxide film.

When the ultraviolet rays contained in the flame are incident on the ultraviolet detector, a discharge phenomenon occurs between the anode electrode 32 and the cathode electrode 42. The algorithm and circuit for detecting a flame with a change in voltage or current due to the discharge may adopt a conventional technique.

DESCRIPTION OF SYMBOLS 10 Glass tube 11, 24, 32 Anode electrode 12, 28, 42 Cathode electrode 13, 14 Lead wire 21 Upper cover of UV tube 22 Lower cover of UV tube 23,26 Glass plate 25 Conductive lead (through electrode)
27 Cavity 29 Conductive lead (through electrode)
31 Si base upper lid of UV detection part 33 Joint part with lower lid 41 Si base lower lid of UV detection part 43 Joint part with upper lid 51 Glass for insulation

Claims (2)

A glass tube made of at least a part of an ultraviolet transmitting material, and an ultraviolet detector is installed inside the glass tube. The ultraviolet detector is a mesh-like flat plate anode electrode and a flat plate placed opposite to the anode electrode. In the flame detection sensor comprising a cathode electrode and a conductive conductor on the outside of the glass tube from the flat plate anode electrode and the flat plate cathode electrode , the ultraviolet detection unit has an upper lid of the Si base having a mesh-shaped hole , The joint surface of the lower lid of the Si substrate is processed so as to be parallel, and the upper lid and the lower lid are directly bonded or joined by anodic bonding, and the anode electrode is attached to the upper lid of the Si substrate. Moreover the have a cathode electrode on the lower lid of the Si base, and a conductive conductor for guiding an electric signal to the outside of the glass tube from the anode electrode and the cathode electrode Flame detection sensor, wherein the door.
In claim 1,
The anode electrode of the upper lid of the ultraviolet detection unit is formed by vapor-depositing a metal electrode on one side of the upper lid, and the cathode electrode on the bottom surface of the recess of the lower lid formed into a concave shape is a metal electrode. A flame detection sensor characterized by being formed by vapor deposition .