JP4762508B2 - Physical quantity detection sensor and sensing device - Google Patents

Description

  The present invention relates to a physical quantity detection sensor and a sensing device, and more particularly to a physical quantity detection sensor and a sensing device used when sensing dissolved oxygen concentration, atmospheric oxygen concentration, pH, pressure, and the like.

  Conventionally, in a sensing system that measures dissolved oxygen concentration, pH, etc. in water using a sensor, the sensor is washed with a rotating brush or the sensor is oscillated in order to prevent deterioration in sensor measurement accuracy due to dirt. Prevents dirt from sticking.

  However, cleaning with a rotating brush has problems such as a large sensor structure, dust on the brush, and high power consumption for rotation.

  In addition, when a structure in which the sensor is mechanically oscillated is employed when the sensor is oscillated to prevent contamination, not only the system is increased in size but also power consumption is increased. On the other hand, if a structure that swings the sensor with the flow of water is adopted, an increase in the size of the system and an increase in power consumption can be avoided, but a sufficient contamination prevention effect can be obtained when the flow of water is slow. There is no problem.

  By the way, the following patent document 1 discloses that a photocatalyst is used as a technique for preventing contamination of the inner surface of a flow path provided for flowing a liquid to be measured.

  For example, as shown in FIG. 15, a photocatalyst layer 110 is formed on one surface of the flow path 111, and ultraviolet light is irradiated through the flow path 111. The ultraviolet light multi-reflects the photocatalyst 110 and the reflection surface 112 a of the glass 112 covering the channel 111. In this case, the LED 113 and the photodiode 114 are attached above the glass 112.

However, in such a structure, the photocatalyst layer 110 is irradiated with ultraviolet light through the flow path 111, so that the ultraviolet light is attenuated as the transparency of the liquid flowing in the flow path 111 decreases, thereby causing the photocatalyst. The amount of ultraviolet light applied to the layer 110 is reduced, and a sufficient cleaning effect cannot be obtained.
JP 2000-61447 A

  An object of this invention is to provide the physical quantity detection sensor and sensing apparatus which can prevent adhesion of dirt.

According to a first aspect of the present invention, there is provided a sensor head that is attached to a sensor installation region and measures a dissolved oxygen concentration, an oxygen-permeable light-transmitting film that is installed at a bottom portion of a casing of the sensor head, and the oxygen-permeable light. A photocatalyst layer formed on the measurement atmosphere side of the permeable membrane, and an optical fiber for irradiating the photocatalyst layer with light disposed on the inside of the sensor head of the oxygen permeable light permeable membrane. An optical fiber having a surface fixed in contact with the upper surface of the oxygen-permeable light-transmitting film .

According to a second aspect of the present invention, there is provided a sensor head that is attached to a sensor installation region and measures a dissolved oxygen concentration, an oxygen-permeable light-transmitting film that is installed at a bottom portion of a casing of the sensor head, and the oxygen-permeable light. An optical fiber optically coupled to a light source for irradiating light to the photocatalyst layer disposed inside the sensor head of the oxygen permeable light permeable film, and a photocatalyst layer formed on the measured atmosphere side of the permeable film A sensor including an optical fiber having a distal end surface in contact with and fixed to the upper surface of the oxygen permeable light permeable film, and a data processing unit for processing data output from the sensor; It is a dissolved oxygen concentration sensing apparatus characterized by having.

  As described above, according to the physical quantity detection sensor and the sensing device of the present invention, the photocatalyst layer is formed on the detection surface of the sensor, and the sensor is irradiated with light from an optical element such as an optical fiber or a light emitting element. Yes.

  Therefore, the cleaning effect by the photocatalytic action is produced on the detection surface of the sensor, and it is difficult to be affected by the external environment, and the adhesion of dirt on the sensor can be prevented.

Embodiments of the present invention will be described below in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a top view of a physical quantity detection sensor showing a first embodiment of the present invention, and FIG. 2 is a cross-sectional view of the physical quantity detection sensor.

  1 and 2, the sensor unit 1 includes a cylindrical casing 4 that is hermetically sealed by an upper lid 2 and a lower lid 3, and an electronic circuit board 5 attached on the lower lid 3 in the casing 4. A light emitting element 6 and a light branching unit 7 attached on the lower lid 3, and a sensor head 8 for detecting the oxygen concentration attached to the approximate center of the lower lid 3. The upper lid 2, the lower lid 3, and the housing 4 are made of a corrosion-resistant material or the like, and for example, stainless steel is preferable.

  The optical branching unit 7 is a non-reciprocal light device having an N terminal (a positive number of N ≧ 3) having a function of separating incident light and outgoing light, for example, and penetrates the side surface of the housing 4 in an airtight state. A first input / output port to which the first optical fiber 10 drawn from one end of the attached optical cable 9 is connected and a second optical fiber 11 optically coupled to the light output surface of the light emitting element 6 are connected. 2 input / output ports, a third input / output port to which a third optical fiber 13 drawn to the power generation circuit 12 of the electronic circuit board 5 is connected, and other input / output ports.

  In the electronic circuit board 5, the power generation circuit 12 includes an optical / power converter that converts light incident from the third optical fiber 13 into electric power, and the converted electric power is transmitted to the electric double layer capacitor 19 for power storage. Is done. In addition, an amplifier circuit 15 is connected to the capacitor 19 via a semiconductor switch 14. The amplifier circuit 15 boosts a voltage to supply power to the sensor head 8, for example, and amplifies a measurement signal of the sensor head 8. Then, it is configured to output to the light emitting element driving circuit 16. The light emitting element driving circuit 16 emits an optical signal from the light output surface of the light emitting element 6 to the second optical fiber 11 by sending a signal based on the measurement signal of the sensor head 8 to the light emitting element 6 through the wiring 17. It is configured to let you.

  The semiconductor switch 14 is constituted by a transistor, for example, and is driven by a control signal from the power generation circuit 12 transmitted via the wiring 29a when a predetermined condition is satisfied, thereby amplifying the accumulated power of the capacitor 19 Supply to circuit 15.

  As shown in FIG. 3, the sensor head 8 has a casing 8 a that protrudes outward from the lower lid 3. At the bottom of the casing 8a, an opening 8b that is covered with an oxygen permeable light permeable film 20 (for example, a polytetrafluoroethylene film) is formed. The inside of the casing 8a is a sensor installation area that is spatially partitioned from the atmosphere to be measured, and is an area that does not contact the atmosphere to be measured except for the oxygen-permeable light permeable film 20.

  One end face of the fourth optical fiber 21 is connected and fixed to the upper surface of the oxygen permeable light transmissive film 20 with an adhesive. The fourth optical fiber 21 may be connected to an external light source through the optical cable 9 or branched from the third optical fiber 13 connected to the optical branching unit 7. There may be.

  For example, a titanium oxide layer is formed as the photocatalyst layer 22 on the lower surface of the oxygen permeable light transmissive film 20. The titanium oxide layer can have light permeability and oxygen permeability by adjusting the manufacturing method, film thickness, and the like. For example, a method in which titanium oxide powder is dissolved in a polytetrafluoroethylene film, a method in which a titanium peroxide solution is partially baked, or a titanium oxide hybrid photocatalyst particle is mixed using an oxygen-permeable silicone polymer as a binder. It is formed by the method to do. The titanium oxide hybrid photocatalyst particles are obtained by attaching an inactive ceramic as a photocatalyst to the surface of the titanium oxide photocatalyst particles.

  Further, for example, potassium hydroxide (KOH) is stored in the casing 8a as the electrolytic solution 8c. In the electric field solution 8c, the cathode 8d connected to the first signal line 18a connected to the amplifier circuit 15 is connected to the oxygen-permeable light. An anode 8e disposed near the transmission film 20 and connected to the second signal line 18b connected to the amplifier circuit 15 is disposed above the cathode 8d. The cathode 8d is made of, for example, silver (Ag), gold (Au), copper (Cu), and the like, and the anode 8e is made of, for example, lead (Pb), tin (Sn), or the like.

  1 and 2, reference numeral 28 a denotes a bracket for fixing the optical cable 9 to the housing 4, 28 b denotes a screw for fixing the upper lid 2, the lower lid 3, etc. to the housing 4, and 28 c denotes the housing 4. Packings 29 b to 29 d for maintaining the airtightness of the upper lid 2, the lower lid 3, etc., indicate wirings connected to the electronic circuit board 5.

  In the physical quantity detection sensor as described above, the light propagating through the third optical fiber 13 and irradiated on the light / power converter of the power generation circuit 1 is converted into electric power. This electric power is accumulated in the capacitor 19 via the wiring 29b and then supplied to the sensor head 8 via the wiring 29c, the semiconductor switch 14, the amplifier circuit 15, and the first and second signal lines 18a and 18b.

  Then, when electric power is supplied to the sensor head 8, oxygen enters the electrolytic solution 8 c of the sensor head 8 through the photocatalyst layer 22 and the oxygen-permeable light-transmitting film 20 from the atmosphere to be measured from the outside. A current having a magnitude corresponding to the concentration flows between the cathode 8d and the anode 8e.

  The current is output to the light emitting element driving circuit 16 through the amplifier circuit 15 as a signal indicating the oxygen concentration, and the light emitting element driving circuit 16 changes the light emitting state of the light emitting element 6 according to the input signal. Furthermore, the signal light output from the light emitting element 6 propagates in the first optical fiber 10 via the second optical fiber 11 and the optical branching unit 7 and further propagates through the optical cable 9 to an external processing device. The

  On the other hand, light supplied from a light source (not shown) outside the sensor unit 1 through the first optical fiber 10 in the optical cable 9 propagates through the optical branching unit 7 and the third optical fiber 13. Are introduced into the power generation circuit 12, and are branched by the optical branching unit 7 and propagated to the fourth optical fiber 21. Here, an ultraviolet light source is used as the light source.

  The ultraviolet light emitted from the fourth optical fiber 21 passes through the oxygen permeable light transmissive film 20 and is irradiated to the photocatalyst layer 22. Since the photocatalyst layer 22 has a light transmission structure, the surface exposed to the outside of the photocatalyst layer 22 is also irradiated with ultraviolet light.

Accordingly, contaminants adhering to the outer surface of the photocatalyst layer 22 are also decomposed by the photocatalytic reaction of the photocatalyst layer 22.
Further, since the tip surface of the fourth optical fiber 21 is fixed in contact with the oxygen-permeable light-transmitting film 20, it is not contaminated.

  Moreover, since the photocatalyst layer 22 is irradiated with light from the inside of the sensor head 8, even if the transparency of the atmosphere in which the sensor head 8 is placed is lowered, the anti-contamination effect by the photocatalyst layer 22 is maintained.

  By the way, in the sensor unit 1, as shown in FIG. 4, the wavelength is in the middle of the optical path from the optical branching unit 7 to the oxygen permeable light transmitting film 20 in the fourth optical fiber 21 drawn into the sensor head 8. A structure for connecting the conversion element 23 may be adopted.

The wavelength conversion element 23 is composed of a nonlinear optical crystal such as β-BaB ₂ O ₄ , LiNbO ₃ , LiIO ₃ , LiB ₃ O ₅ , Sr ₂ Be ₂ BO ₇ , CsLiB ₆ O ₁₀ , KTiOPO _{4, and the} like. The light (for example, infrared light) incident through the optical fiber 10 and the optical branching unit 7 is converted into ultraviolet light (UV).

  According to such a structure, when using, for example, infrared light as light propagating from the optical branching unit 7 to the fourth optical fiber 21, the light can be converted into ultraviolet light by the wavelength converter 23. Thereby, the ultraviolet light emitted from the fourth optical fiber 21 passes through the oxygen permeable light permeable film 20 and is irradiated to the photocatalyst layer 22.

  By the way, when it is desired to further expand the light irradiation region to the oxygen permeable light transmissive film 20 and the photocatalyst layer 22, a plurality of fourth optical fibers 21 bundled by a bundle 24 are provided as shown in FIG. If they are separated from each other and their tips are connected to a plurality of locations of the oxygen permeable light permeable film 20, the light irradiation region of the photocatalyst layer 22 is expanded, and the decomposition efficiency of contaminants can be increased.

  When the light propagating through the fourth optical fiber 21 is light other than ultraviolet light, for example, infrared light, light is transmitted in the middle of the optical path of the plurality of fourth optical fibers 21 as shown in FIG. A structure for connecting the wavelength converter 23 may be adopted. Thereby, ultraviolet light is irradiated to a wide area of the photocatalyst layer 22.

  Note that at least a portion of the sensor head 8 where light leaks is formed with a light leakage prevention structure including a light absorption layer or the like. This leakage light preventing structure may be formed anywhere on the outer peripheral surface of the housing of the sensor head 8 positioned other than the detection surface of the photocatalyst layer. With this leakage light prevention structure, generation and adhesion of algae and the like can be prevented. This structure can be similarly applied to the following embodiments.

(Second Embodiment)
In the present embodiment, a physical quantity detection sensor having a structure for preventing contamination of a sensor head for pH measurement will be described.
FIG. 7 is a cross-sectional view showing a sensor head of a physical quantity detection sensor according to the second embodiment of the present invention.

  In FIG. 7, a hole 62 is formed in the bottom portion of the sensor head casing 61 for introducing a liquid to be measured for pH from the outside. In the casing 61, a glass electrode 63 filled with a predetermined liquid and a reference electrode 64 are arranged apart from each other. Further, signal lines 67 and 68 are connected to the glass electrode 63 and the reference electrode 64, respectively.

  The transparent film 64 is in close contact with the pH detection surface at the end of the glass electrode 63, and the photocatalyst layer 65 is in close contact with the surface of the transparent film 64 opposite to the pH detection surface. Further, the light emitting portion of the optical element 66 is closely attached to the side surface of the transparent film 64 that is not covered with the photocatalytic layer 65. As the optical element 66, for example, the optical fiber described in the first embodiment or the light emitting element described in the sixth embodiment described later is used.

  In this embodiment, the ultraviolet light emitted from the optical element 66 next to the transparent film 64 propagates through the transparent film 64 and is irradiated to the photocatalyst layer 65, thereby causing a cleaning effect by the photocatalytic action in the photocatalyst layer 65. Contamination of the detection surface of the glass electrode 63 is prevented. As a result, a decrease in sensitivity due to contamination of the glass electrode 63 can be prevented.

  The direction of irradiating light to the transparent film 64 may be any of the lateral direction, the vertical direction, and the oblique direction with respect to the transparent film 64, but the light irradiation area increases by irradiating from the oblique direction. Therefore, the photocatalytic effect can be easily obtained. The same applies to the above-described embodiment and the embodiments described later.

(Third embodiment)
In the present embodiment, a physical quantity detection sensor having a structure for preventing contamination of a sensor head for pressure measurement will be described.
FIG. 8 is a cross-sectional view showing a sensor head of a physical quantity detection sensor according to the third embodiment of the present invention.

  In FIG. 8, a diaphragm 72 that is deformed by a pressure difference with the outside is attached to the bottom of the casing 71 of the sensor head. In addition, a strain gauge 73 that is attached on the diaphragm 72 and measures the pressure from the strain amount of the diaphragm 72 is attached to the inside of the casing 71. Further, the strain gauge 73 is connected to a signal line 74 that is drawn into the casing 71.

  A transparent film 75 is closely attached to the detection surface of the diaphragm 72 facing the outside of the casing 71, and a photocatalyst layer 76 is closely attached to the surface of the transparent film 75 opposite to the diaphragm 72. Yes.

  Further, the light emitting portion of the optical element 77 is closely attached to the side surface of the transparent film 75 that is not covered with the photocatalytic layer 76. As the optical element 77, for example, the optical fiber described in the first embodiment or the light emitting element described in the sixth embodiment to be described later is used.

  In this embodiment, the ultraviolet light emitted from the optical element 77 to the transparent film 75 propagates through the transparent film 75 and is irradiated to the photocatalyst layer 76, thereby causing a cleaning effect by the photocatalytic reaction in the photocatalyst layer 76. Contamination of the detection surface of the diaphragm 72 is prevented. As a result, a decrease in sensitivity due to the contamination of the diaphragm 72 is prevented.

(Fourth embodiment)
In the present embodiment, a physical quantity sensing system having a structure for preventing adhesion of contaminants attached to the surface of a sensor unit that detects not only oxygen concentration, pH concentration, and pressure but also gas concentration, transparency, and other physical quantities will be described.

  FIG. 9 is a configuration diagram showing a physical quantity detection sensing system according to the fourth embodiment of the present invention. In FIG. 9, the same reference numerals as those in FIG. 3 denote the same elements.

  In FIG. 9, the physical quantity sensing system includes a sensor head 31 that detects a gas quantity, transparency, and other physical quantities, a housing 32 that stores the sensor head 31, and a converter that converts an output signal of the sensor head 31 into a predetermined signal. 33 and a data processing device 34 that is provided outside the housing 32 and calculates a measured value of the physical quantity based on the output data of the converter 33.

  An opening 36 covered with a transparent film 35 is formed on one surface of the housing 32 that houses the sensor head 31, and a photocatalyst layer 37 is formed on the outer surface of the transparent film 35. The inside of the housing 32 is a sensor installation area that is spatially partitioned from the atmosphere to be measured.

  The transparent film 35 is made of a light transmissive material such as vinyl chloride, silicon oxide, or fluororesin, and the photocatalyst layer 37 is made of the same material as the photocatalyst layer 22 described in the first embodiment.

  In the housing 32, the other end of the first optical fiber 39 connected at one end to an infrared light source 38 installed outside the casing 32 is disposed, and infrared light is converted into ultraviolet light at the other end. One end of the second optical fiber 41 is connected via an optical wavelength conversion element 40 for conversion. Further, the other end of the second optical fiber 41 is in contact with the surface of the transparent film 35 from the inside of the housing 32.

  In this physical quantity detection sensing system, a physical quantity measurement signal based on the physical quantity measured by the sensor head 31 is input to the converter 33 via the signal line 42. Further, the signal output from the converter 33 is calculated as a physical quantity measurement signal by the data processing device 34.

  The infrared light emitted from the infrared light source 38 propagates through the first optical fiber 39 and enters the optical wavelength conversion element 40. Then, the light wavelength conversion element 40 converts infrared light into ultraviolet light, and irradiates the ultraviolet light to the transparent film 35 and the photocatalyst layer 37 via the second optical fiber 41. Further, since the photocatalyst layer 37 has a structure that transmits light, the ultraviolet light transmitted through the inside of the photocatalyst layer 37 is also irradiated to the surface of the photocatalyst layer 37 that is exposed outside the housing 32.

  Therefore, on the surface of the photocatalyst layer 37, contaminants are decomposed by the catalytic reaction of the photocatalyst layer 37, and light incident into the housing 32 from the outside is prevented from being blocked. Further, when a gas permeable structure is adopted for the photocatalyst layer 37 and the transparent film 35, contamination of the surface of the photocatalyst layer 37 is prevented, and the gas inlet on the surface of the sensor head 31 is prevented from being blocked. The

  On the other hand, since the second optical fiber 41 is attached to the inside of the housing 32 where the sensor head 31 is placed, the photocatalytic reaction caused by the ultraviolet light irradiation is less affected by the external environment of the housing 32. Furthermore, since the tip surface of the second optical fiber 41 is fixed in contact with the transparent film 35, it is not easily contaminated.

  By the way, in the above-described structure, infrared light propagating in the first optical fiber 39 is converted into ultraviolet light by the light wavelength conversion element 40.

  However, when an ultraviolet light source can be installed outside the housing 32, one end of the second optical fiber 41 is optically coupled to the ultraviolet light source 43, as shown in FIG. May be transmitted through the transparent film 35 from the other end of the second optical fiber 41 to irradiate the photocatalyst layer 36. In this case, the optical wavelength converter 40 is omitted.

(Fifth embodiment)
In the present embodiment, from the viewpoint of ecology, a system having a structure that irradiates the photocatalyst layer with ultraviolet light using natural light such as sunlight without using a light source based on electric energy will be described.

FIG. 11 is a block diagram showing a physical quantity detection sensing system according to the fifth embodiment of the present invention. The same reference numerals as those in FIG. 9 denote the same elements.
In FIG. 11, an optical cable 45 in which a plurality of optical fibers 44 are bundled is attached to the housing 32, and one ends of these optical fibers 44 are separated from each other and drawn into the housing 32. The transparent film 35 covering the portion 36 is connected to the upper surface. The other end of the optical fiber 44 is drawn out of the housing 32 and connected to the condenser 46.

The condenser 46 has a structure that collects natural light and makes it incident on the optical fiber 44 in the optical cable 45.
In the physical quantity detection sensing system having such a structure, the light collected by the condenser 46 propagates through the optical fiber 44 and is introduced into the housing 32 and is irradiated onto the transparent film 35.

  The ultraviolet light contained in the natural light irradiated on the transparent film 35 passes through the transparent film 35 and reaches the photocatalyst layer 37. Since the photocatalyst layer 37 has optical transparency, the ultraviolet light is scattered and transmitted through the transparent film 35 and irradiated on the lower surface side.

  Therefore, on the surface of the photocatalyst layer 37, contaminants are decomposed by the photocatalytic reaction, and light incident on the housing 32 from the outside is not blocked. Further, when a gas permeable structure is employed for the photocatalyst layer 37 and the transparent film 35, the surface of the photocatalyst layer 37 is prevented from being contaminated and the gas inlet on the surface of the sensor head 31 is prevented from being blocked. The

  On the other hand, since the optical fiber 44 is drawn into the housing 32 in which the sensor head 31 is placed, the photocatalytic reaction due to the ultraviolet light irradiation is not easily influenced by the external environment of the housing 32. Furthermore, since the front end surface of the optical fiber 44 for supplying ultraviolet light is fixed in contact with the transparent film 35, it is not easily contaminated.

  By the way, when the light condensed by the condenser 46 is sunlight, it becomes impossible to irradiate the photocatalyst layer 37 at night, so the light source 38 shown in the fourth embodiment is applied to the optical fiber 38. You may combine and introduce temporarily at night. Even in this case, since solar energy is used in the daytime, power consumption can be reduced.

(Sixth embodiment)
In the present embodiment, it will be described that a structure in which light emitted to the photocatalyst layer is emitted from the light emitting element is employed.
FIG. 12 is a configuration diagram showing a physical quantity detection sensing system according to the sixth embodiment of the present invention.

  12, the physical quantity sensing system includes a sensor head 31 that detects a physical quantity, a casing 32 that stores the sensor head 31, a converter 33 that converts an output signal of the sensor head 31 into a predetermined signal, and a casing 32. And a data processing device 34 that calculates a measured value of the physical quantity based on the output data of the converter 33.

  The opening 36 of the housing 32 that houses the sensor head 31 is covered with a transparent film 35, and a photocatalyst layer 37 is formed on the outer surface of the transparent film 35. The transparent film 35 and the photocatalyst layer 37 are made of the same material as the transparent film 20 and the photocatalyst layer 22 described in the fourth embodiment, respectively.

  Further, the other end of the optical fiber 52 having one end connected to a light source 88 for supplying light energy installed outside is drawn into the housing 32, and the other end is a light / power that converts light into electric power. A converter 53 is attached.

A light output element 54 that emits ultraviolet light, for example, a semiconductor laser for supplying ultraviolet light, and an LED are connected to the power output terminal of the light / power converter 53.
In this physical quantity detection sensing system, a physical quantity measurement signal based on the physical quantity measured by the sensor head 31 is input to the converter 33 via the signal line 42. Further, the signal output from the converter 33 is calculated as a physical quantity measurement signal by the data processing device 34.

  The light emitted from the light source 51 propagates through the optical fiber 52 and enters the light / power converter 53. The light / power converter 53 converts light into electric power and supplies the electric power to the light emitting element 54.

  Thereby, the light emitting element 54 irradiates the transparent film 35 and the photocatalyst layer 37 with ultraviolet light. Further, since the photocatalyst layer 37 has a structure that transmits light, the ultraviolet light transmitted through the inside of the photocatalyst layer 37 is also irradiated to the surface of the photocatalyst layer 37 that is exposed outside the housing 32.

Therefore, on the surface of the photocatalyst layer 37, the contaminants are decomposed by the photocatalytic reaction of the photocatalyst layer 37 as in the second embodiment.
On the other hand, since the light emitting element 54 is attached to the inside of the housing 32 where the sensor head 31 is placed, the photocatalytic action by the ultraviolet light irradiation is not easily influenced by the external environment of the housing 32.

Note that a diffusion lens (not shown) may be attached to the light emitting surface of the light emitting element 54 to widen the ultraviolet light irradiation region in the photocatalyst layer 37.
By the way, in the structure shown in FIG. 12, power is supplied to the light emitting element 54 by the light / power converter 53, but when there is a space for mounting the battery in the housing 32, it is shown in FIG. As described above, the battery 55 may be connected to the light emitting element 34 to supply power. According to this, it is possible to irradiate the photocatalyst layer 37 with ultraviolet light even when there is not enough room for the number of optical fibers drawn into the housing 32 or when there is no appropriate light source outside the housing 32. become.

  In the present embodiment, a light emitting element is used as the optical element, and in the first to fifth embodiments, an optical fiber is used as the optical element, and the photocatalyst layer is irradiated with ultraviolet light through the transparent film. Is adopted.

When an optical fiber is used as the optical element, light can be sent from a remote location, so that the contamination prevention process can be performed even when the power line cannot be supplied into the sensor unit or when natural light cannot be taken in.
In addition, when a transparent film is unnecessary, you may irradiate an ultraviolet light directly to a photocatalyst layer from an optical element.

(Seventh embodiment)
In the present embodiment, a physical quantity detection sensor in which the transparent body formed between the sensor and the photocatalyst layer in the above-described embodiment is configured from an optical waveguide will be described.
FIG. 14 is a cross-sectional view showing a sensor head of a physical quantity detection sensor according to the seventh embodiment of the present invention.

  In FIG. 14, a transparent body 82 formed of an optical waveguide is formed on the detection surface of the sensor head 81, and a photocatalyst layer 83 is formed on a portion of the transparent body 82 opposite to the sensor head 81. Yes. A signal line 84 is connected to the sensor head 81.

  As an optical waveguide constituting the transparent body 82, for example, a single mode or multimode optical fiber, an optical integrated circuit, or the like is used. In the case of using an optical fiber, the optical fiber may be arranged with an arbitrary bending radius or larger so that light propagating therein leaks from the core and cladding, or the core may be eccentric. When using an optical integrated circuit, the core may be designed to be closer to the photocatalytic layer.

FIG. 1 is a top view of a sensor used in the physical quantity detection system according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view of a sensor used in the physical quantity detection system according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view showing a first example of a sensor head used in the physical quantity detection system according to the first embodiment of the present invention. FIG. 4 is a cross-sectional view showing a second example of a sensor head used in the physical quantity detection system according to the first embodiment of the present invention. FIG. 5 is a cross-sectional view showing a third example of the sensor head used in the physical quantity detection system according to the first embodiment of the present invention. FIG. 6 is a cross-sectional view showing a fourth example of a sensor head used in the physical quantity detection system according to the first embodiment of the present invention. FIG. 7 is a sectional view showing a sensor head used in the physical quantity detection sensing system according to the second embodiment of the present invention. FIG. 8 is a cross-sectional view of a sensor head used in the physical quantity detection sensing system according to the third embodiment of the present invention. FIG. 9 is a configuration diagram of a physical quantity detection sensing system according to the fourth embodiment of the present invention. FIG. 10 is a configuration diagram illustrating another aspect of the physical quantity detection sensing system according to the fourth embodiment of the present invention. FIG. 11 is a configuration diagram showing a physical quantity detection sensing system according to the fifth embodiment of the present invention. FIG. 12 is a configuration diagram showing a physical quantity detection sensing system according to the sixth embodiment of the present invention. FIG. 13: is a block diagram which shows the other aspect of the physical quantity detection sensing system which concerns on the 6th Embodiment of this invention. FIG. 14: is a block diagram which shows the sensor used for the physical quantity detection sensing system which concerns on the 7th Embodiment of this invention. FIG. 15 is a cross-sectional view illustrating an example of a conventional physical quantity detection sensor.

Explanation of symbols

1: Sensor unit 2: Upper lid 3: Lower lid 4: Housing 5: Electronic circuit board 6: Light emitting element 7: Light branching unit 8: Sensor head 8a: Casing 8b: Opening 9: Optical cables 10, 11, 13, 21 : Optical fiber 12: Power generation circuit 14: Semiconductor switch 15: Amplifier circuit 16: Light emitting element drive circuit 19: Capacitor 20: Oxygen permeable light transmissive film 22: Photocatalyst layer 23: Wavelength conversion element 31: Sensor head 32: Housing 35 64, 75: Transparent film 36: Openings 37, 48, 65, 76, 83: Photocatalyst layer 38: Infrared light source 39, 41: Optical fibers 44, 49, 52: Optical fiber 46: Condenser 51: Light source 53: Light source 54: Light emitting element 66, 77: Optical element 82: Transparent body

Claims (15)

A sensor head attached to the sensor installation area and measuring the dissolved oxygen concentration;
An oxygen-permeable light-transmitting film installed at the bottom of the casing of the sensor head;
A photocatalyst layer formed on the measured atmosphere side of the oxygen-permeable light-transmitting film;
An optical fiber installed on the inner side of the sensor head of the oxygen permeable light permeable film for irradiating light to the photocatalyst layer , the tip surface of which is in contact with the upper surface of the oxygen permeable light permeable film A fixed optical fiber ;
A dissolved oxygen concentration sensor comprising:   The dissolved oxygen concentration sensor according to claim 1, wherein the photocatalyst layer is formed on a part of the oxygen permeable light permeable film.   2. The dissolved oxygen concentration sensor according to claim 1, wherein the photocatalyst layer is obtained by dissolving a photocatalyst powder in the oxygen permeable light permeable film.   The photocatalyst layer is formed by mixing the oxygen-permeable light-transmitting film with hybrid photocatalyst particles in which an inert ceramic is attached to the surface of the photocatalyst particles using an oxygen-permeable silicone polymer as a binder. The dissolved oxygen concentration sensor according to claim 1.   The dissolved oxygen concentration sensor according to any one of claims 1 to 4, wherein the oxygen-permeable light-transmitting film is a polytetrafluoroethylene film. A sensor head attached to the sensor installation area for measuring the dissolved oxygen concentration, an oxygen permeable light permeable film installed at the bottom of the casing of the sensor head, and formed on the measured atmosphere side of the oxygen permeable light permeable film And an optical fiber optically coupled to a light source for irradiating the photocatalyst layer with light disposed on the inside of the sensor head of the oxygen permeable light permeable film , the tip surface of which is the optical fiber. A sensor comprising an optical fiber fixed in contact with the upper surface of the oxygen permeable light permeable membrane ;
A dissolved oxygen concentration sensing device comprising: a data processing unit for processing data output from the sensor. The dissolved oxygen concentration sensing device according to claim 6 , wherein the photocatalyst layer is formed on a part of the oxygen permeable light permeable film. The dissolved oxygen concentration sensing device according to claim 6 , wherein the photocatalyst layer is obtained by dissolving a photocatalyst powder in the oxygen permeable light permeable film. The photocatalyst layer is formed by mixing the oxygen-permeable light-transmitting film with hybrid photocatalyst particles in which an inert ceramic is attached to the surface of the photocatalyst particles using an oxygen-permeable silicone polymer as a binder. The dissolved oxygen concentration sensing device according to claim 6 . It said oxygen permeable light transmitting film, the dissolved oxygen concentration sensing apparatus according to any one of claims 6 to 9, characterized in that a polytetrafluoroethylene membrane. The dissolved oxygen concentration sensing device according to claim 6 , wherein the light source is an ultraviolet light source. The dissolved oxygen concentration sensing device according to claim 6 , wherein the light source is optically coupled to the optical fiber via a wavelength converter. The dissolved oxygen concentration sensing device according to claim 12 , wherein the wavelength converter has a structure for converting into ultraviolet light. The dissolved oxygen concentration sensing device according to claim 6, wherein a plurality of the optical fibers are arranged in the sensor installation region and separated from each other. The optical fiber, the dissolved oxygen concentration sensing apparatus according to claim 6, characterized in that you are drawn to natural light irradiation area from the sensor installation region.

Images