JPH0650921A - Odor sensor - Google Patents

Abstract

PURPOSE:To omit spot welding for lead wires and to decrease power consumption by providing a heat insulating means comprising heat insulator, whose heat conductivity is lower than that of the substrate in a sensor part, around the sensor part. CONSTITUTION:A sensor part S comprises a sensor element 3 and a sensor electrode 4 made of the thin films of tin (IV) oxide or the like and a heating part, which is located at the opposite surface of a element substrate 1 with respect to the element 3. The sensor part S is attached to the substrate 1 comprising alumina or the like. At this time, a heat insulating part comprising a heat insulator 2, whose heat conductivity is lower than that of the substrate 1, such as glass material or the like is provided around the sensor part S. Thus, efficient heat insulation is performed on the substrate 1. Therefore, the heat insulation of the sensor part S in the substrate 1 becomes excellent. The substrate 1 can be directly fixed to a circuit board 7 and terminals 6 by soldering and the like. In this way, it is not necessary to perform spot welding for lead wires costing much labor, and power consumption can be also decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an odor sensor, and more particularly to an odor sensor in which a sensor portion and other portions are efficiently thermally insulated on a substrate.

[0002]

2. Description of the Related Art In recent years, as a method for early detection of a fire, a method of detecting a burning odor generated before smoke in a fire by an odor sensor has attracted attention. In a conventional odor sensor, as shown in FIG. 4, a plurality of terminals 6 are provided at intervals on a circuit board 7 such as a glass board on which a main electric circuit is mounted. The lead wire 10 for the electrode 4 for the heater and the electrode (not shown) for the heater are attached by welding.
The alumina substrate having the sensor portion S was supported. The sensor portion S on the alumina substrate is composed of a sensor element 3 (for example, stannic oxide) and a heater (not shown) printed and fired on the opposite surface of the sensor element 3 through the substrate. Had heated the heater to 350 ° C. or higher in order to sensitively detect odor. As described above, in the conventional odor sensor, since the sensor portion is fixed on the upper portion of the circuit board 7 by the lead wire 10, conduction of heat generated by heating the heater is prevented, which adversely affects other circuits. It had no effect.

[0003]

However, in such a conventional odor sensor, it is necessary to attach lead wires to the substrate in advance and carefully arrange each lead wire on the nail of the terminal to perform spot welding. It was very time-consuming. An object of the present invention is to solve the conventional problems as described above, and to provide an odor sensor in which a sensor portion and other portions are efficiently thermally insulated on a substrate without performing troublesome spot welding. It is what

[0004]

As a result of earnest studies, the present inventors were able to solve the above-mentioned conventional problems. That is, the first aspect of the present invention is that, in a odor sensor in which a sensor unit including a sensor element and a heating unit that heats the sensor element is provided on a substrate, a heat insulating unit is provided around the sensor unit on the substrate. The present invention provides a characteristic odor sensor. A second aspect of the present invention is that the heat insulating means is
The above odor sensor is provided in which a heat insulating material having a lower thermal conductivity than the substrate of the sensor section is interposed in the substrate.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is an element substrate made of alumina or the like, 2 is a heat insulating material interposed in the opening of the substrate 1 as a heat insulating means, 3 is a sensor element (for example, sputter-deposited thin film stannic oxide), 4 is a sensor electrode 5 is a conductor pattern obtained by screen-printing a gold paste and baked, 6 is a terminal,
7 is the above-mentioned circuit board. As shown in FIG. 2, a heating portion, for example, a heater 8 made of ruthenium oxide formed of a paste is provided on the opposite surface of the sensor element 3 through the substrate 1 to form a sensor portion S. The heat insulating means that can be used in the present invention is, for example, a glass material (7 to 10).
W · m ⁻¹ · K ⁻¹ , alumina substrate is about 210 W · m ·
A heat insulating material such as K ^-1 ) can be used. The heat insulating material that can be used for the odor sensor of the present invention has a lower thermal conductivity than the substrate.

Separately from this, by providing only the groove 9 and the opening 9'around the sensor portion of the substrate 1 without providing the heat insulating material 2 as shown in FIGS. 3 and 4, the heat insulating effect can be obtained. By providing the heat insulating means around the sensor element 3 as described above, the heat emitted from the sensor element 3 heated to 350 ° C. or higher is blocked and the heat conduction is suppressed. Therefore, efficient thermal insulation is performed on the substrate 1. Further, since the thermal insulation in the alumina substrate 1 is good as described above, the element substrate 1 can be directly fixed to the circuit substrate 7 and the terminal 6 by soldering or the like, which is a labor required in the conventional technique. There is no need to perform spot welding of the lead wire, which takes a long time. Although the shape of the heat insulating material 2 is illustrated as a square shape in FIG. 1, the shape is not limited to this in the present invention, and the shape, size, etc. can be freely selected depending on the situation. Further, when the heat insulating means is a groove or an opening, its size, depth, shape, etc. can be freely selected. The substrates 1 and 7 may be integrated according to the circuit configuration. In this embodiment, the heater 8 is provided on the back surface of the sensor element 3, but the sensor element 3 may be provided on the upper side of the heater 8 via an insulating layer. Further, this structure is shown for the case of one element, and for example, two or more elements having different components of the sensor element 3 arranged side by side may be arranged. It is possible to identify and eliminate false alarms when determining fire.

[0007]

According to the odor sensor of the present invention, as described in the above embodiment, the heat generated in the sensor section can be efficiently insulated on the substrate by the heat insulating means provided around the sensor section. There is no need to perform troublesome spot welding of lead wires, which is required in the conventional technique, and it is possible to reduce power consumption.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of an odor sensor of the present invention.

FIG. 2 is a vertical cross-sectional view of the sensor unit of FIG.

FIG. 3 is a vertical sectional view similar to FIG. 2, which is another embodiment of the sensor unit.

FIG. 4 is a perspective view showing another embodiment similar to FIG.

FIG. 5 is a perspective view showing an outline of a conventional odor sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Element substrate 2 Heat insulating material 3 Sensor element 4 Sensor electrode 5 Conductive pattern 6 Terminal 7 Circuit board 8 Heater 9 Groove 10 Lead wire S Sensor section

Claims (2)

[Claims] 1. An odor sensor in which a sensor section comprising a sensor element and a heating section for heating the sensor element is provided on a substrate, wherein a heat insulating means is provided around the sensor section of the substrate. , Odor sensor. 2. The odor sensor according to claim 1, wherein the heat insulating means has a heat insulating material having a lower thermal conductivity than that of the substrate of the sensor portion interposed in the substrate.