JPS5910486B2 - temperature sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature sensor using a piezoelectric vibrator, particularly a crystal resonator. Specifically, the present invention relates to a temperature sensor using a piezoelectric vibrator, particularly a crystal resonator. The present invention relates to a temperature sensor that detects the vibration frequency of a crystal oscillator proportional to temperature by applying a force proportional to temperature to a child, and thereby measures temperature.

Traditionally known temperature sensors include metal resistance wires and thermistors, but all of them have drawbacks such as power consumption and measurement accuracy.In recent years, however, as manufacturing technology for crystal resonators has advanced, crystal resonators have become easier to obtain. As a result, various temperature sensors using crystal oscillators have been proposed.

Conventionally proposed temperature sensors using crystal oscillators are
In both cases, we focused on the fact that the temperature dependence of the crystal oscillator increases depending on its extraction angle, and the temperature to be measured is determined by the vibration frequency of the crystal oscillator when the crystal oscillator itself reaches the temperature to be measured. Such a crystal resonator includes, for example, a biaxially rotating LC cut plate.

Temperature sensors using crystal oscillators are considered to be superior to temperature sensors using metal resistance wires, thermistors, etc. in terms of power consumption, measurement accuracy, and ease of detecting electrical signals (direct detection with digital signals). Although this method is very good, the crystal resonator itself does not have good thermal conductivity, and therefore it takes a long time for the crystal resonator to reach the temperature to be measured, resulting in a slow response speed. In addition, in the conventional example described above in which the crystal oscillator itself is sensitive to temperature, the sensitivity of the temperature sensor is uniformly determined by the cutting angle of the crystal oscillator, making it difficult to obtain temperature sensors with various sensitivities depending on the application. There are drawbacks.

Furthermore, a crystal resonator as a temperature sensitive element must generally use an LC cut plate, and the LC cut plate is a two-axis rotating type crystal resonator, and a single-axis rotating type crystal resonator, such as an AT cut plate, must be used. Compared to a crystal resonator such as a plate (this AT cut plate can be used in the present invention), it has a drawback that it is less mass-producible. It is an object of the present invention to overcome the above-mentioned conventional drawbacks, and to provide a temperature sensor using a crystal resonator that has a fast response speed, can be manufactured with various sensitivities depending on the application, and can be mass-produced. do.

For this purpose, in the present invention, the periphery of a crystal resonator cut out at a cutting angle that has low temperature dependence and high stress dependence has a thermal conductivity higher than that of the crystal resonator and a coefficient of thermal expansion corresponding to that of the crystal resonator. A member having a coefficient of thermal expansion different from that of the crystal resonator is rigidly fixed, and the temperature is changed to the thermal expansion of the member, thereby applying stress to the periphery of the crystal resonator. The temperature to be measured is determined by changes in the vibration frequency of the crystal oscillator.

With this configuration, the temperature sensing part of the temperature sensor is converted to the above-mentioned highly thermally conductive member, so a temperature sensor that quickly follows the temperature to be measured can be obtained, and the shape of the above-mentioned member can be changed as appropriate. By appropriately changing the material, temperature sensors with various sensitivities can be obtained depending on the application.

Embodiments of the present invention will be described in detail below with reference to the drawings.

All drawings are drawings explaining embodiments of the present invention,
1, 2, and 3 are a plan view, a front view, and a sectional view taken along line A-A in FIG. 1 of the first embodiment, and FIGS. 4 and 5 are the second embodiment. The plan view and BB cross-sectional view in FIG. 4, FIGS. 6 and 7 respectively show specific examples of the support structure and electrical signal derivation lead structure of the temperature sensor according to the present invention. It is an exploded perspective view shown according to.

First, a first embodiment will be explained with reference to FIGS. 1 to 3.

In Figures 1 to 3, 1 is a crystal oscillator, 111 and 1
12 is an electrode, 113 and 114 are electrical signal output paths, 2
1 and 22 are temperature sensing members, 211 and 221 are temperature sensing parts, 2
12 and 222 are joint parts, 213 and 223 are air holes,
31 and 32 are electrical signal derivation leads.

The oscillation frequency of the crystal oscillator 1 does not change due to changes in ambient temperature, or even if it changes, the change is extremely small, and the oscillation frequency changes in proportion to the applied stress. A material cut at an angle with such characteristics, that is, low temperature dependence of vibration frequency and high stress dependence, is used.

Specific examples of crystal resonators with such characteristics include a uniaxially rotating AT cut plate, but other crystal resonators with various cutting angles can also be used.

A circular crystal resonator 1 is used, and electrodes 111 and 112 are formed on both sides of the crystal resonator 1 by, for example, gold plating, and lead-out paths 1 for extracting electrical signals from the electrodes 111 and 112 are used.
13 and 114 are provided in the same manner as a general crystal resonator (for example, a crystal resonator used as an oscillation element), and the lead-out paths 113 and 114 are provided with electrical signal lead-out leads 31 and 3.
2 are connected.

The temperature-sensitive members 21 and 22 are made of a material having higher thermal conductivity and higher coefficient of thermal expansion than the crystal oscillator 1, such as metals such as aluminum and silver, and their structure is such that the temperature changes when the temperature changes.
The strength is such that it can expand or contract while its external shape remains approximately similar, i.e., the strength that will not cause it to bend when it expands, and the strength that will not cause cracks when it contracts. The temperature-sensing portion 2 is set such that the change due to the expansion or contraction described above is transmitted to the crystal resonator 1 to the maximum extent and evenly to its periphery.
11 and 221 are formed into a dome shape with a curved surface.

The curved surface is appropriately set, such as a curved surface having a spherical curvature, taking into consideration the required sensitivity of the temperature sensor and the like. Temperature sensing members 21 and 22 having such a structure are fixed to both surfaces of the crystal resonator 1 to constitute a temperature sensor.

That is, the temperature sensing member 21 is placed around the periphery of the crystal resonator 1.
, 22 are rigidly fixed by appropriate means such as adhesive, soldering, glass welding, etc., and as a result, the electrodes 11 of the crystal resonator 1
1,112 portion and the temperature sensing portion 211 of the temperature sensing members 21, 22,
A space is formed between 221 and 221. The fixation between the crystal resonator 1 and the temperature-sensitive members 21 and 22 is such that the change in the outer shape (expansion or contraction) of the temperature-sensitive member due to temperature change is properly transmitted to the crystal resonator 1 at the fixed portion. It is firmly fixed to prevent any burrs from forming. Electrode 111,1
The part where 12 is formed is the vibrating part of the crystal oscillator 1, and this vibrating part is connected to the temperature sensing members 21 and 22 by the above-mentioned space.
The vibration of the crystal resonator 1 is not inhibited. In addition, air holes 213 are provided in the temperature sensing members 21 and 22.
, 223 are provided, and the air existing in the space formed between the crystal resonator 1 and the temperature sensing parts 211, 221 of the temperature sensing members 21, 22 is This eliminates the influence on the vibration frequency of the crystal resonator 1 when the crystal resonator 1 expands or contracts.

The setting positions of the air holes 213 and 223 are as follows:
, 22 so that stress caused by expansion or contraction of the temperature sensing portion 21 does not prevent the stress from acting uniformly on the periphery of the crystal resonator 1.
It is desirable to set it at the center of 1,221.

When the temperature to be measured rises, the temperature sensing members 21 and 22 expand,
A force in the direction indicated by arrow F1 in FIG. 2, that is, a stretching force acts on the periphery of the crystal resonator 1 fixed to the temperature sensing members 21, 22, and when the temperature to be measured falls, the temperature sensing members 21, 22 contracts, and a force in the direction indicated by arrow F2 in FIG. 2, that is, a compressive force, acts on the periphery of the crystal resonator 1.

Since the vibration frequency of the crystal resonator 1 changes depending on this stretching or compression force, the temperature to be measured can be measured by detecting the vibration frequency using an appropriate electric circuit means. The response speed of the temperature sensor according to the present invention depends on the thermal conductivity of the material of the temperature sensing members 21, 22, the structural shape and dimensions, etc., and the sensitivity depends on the thermal expansion coefficient, the structural It depends on the shape and dimensions of.

In the shape of the first embodiment, the crystal resonator 1 has a diameter of 1211φ (diameter not including the peripheral portions of the temperature-sensitive members 21, 22 in contact with the joints 212, 222), and the temperature-sensitive members 21, 22 When the radius of curvature of the inner diameter of
．． 111 silver, a response speed of about 1 second is obtained. Regarding the sensitivity, since the crystal resonator 1 itself has extremely high sensitivity, it changes due to minute dimensional differences, but if the above-mentioned silver plate is used as an example, a sensitivity of approximately 120 Hz/° C. can be obtained. In addition, in order to manufacture temperature sensors of various sensitivities in the first embodiment, the temperature sensing member 21,
22, the temperature sensing parts 211 and 221 may have different spherical curvatures.

In other words, when the spherical curvature is large, the joint 2 due to temperature change
12, 222 is large and the stress applied to the crystal resonator 1 is large, so a temperature sensor with high sensitivity can be obtained. Also, when the spherical curvature is small, the joint parts 212, 2 due to temperature changes can be obtained.
Since the change in 22 is small and the stress applied to the crystal resonator 1 is small, a temperature sensor with low sensitivity can be obtained. A second embodiment, whose plan view and cross-sectional view are shown in FIGS. 4 and 5, has a faster response speed than the temperature sensor of the first embodiment.

The second example will be described below. Figures 4 and 5
In the figure, 214 and 224 are heat conductive pieces, and the others are the same as in the first embodiment.

In the second embodiment, a plurality of heat-conducting pieces 214, 224 are provided around the temperature-sensitive members 21, 22, thereby increasing the surface area of the temperature-sensing members 21, 22. The time required for the members 21 and 22 to reach the ambient temperature (temperature to be measured) is accelerated. As a result, a temperature sensor having a faster response speed than the first embodiment can be obtained. Heat conductive piece 214
, 224, the temperature sensing members 21, 22
Since the thermal capacity of the temperature sensing members 21 and 22 increases due to the provision of the heat conductive pieces 214 and 224 (a factor that increases the response speed), the heat capacity decreases. In relation to the increase in response speed (a factor that slows down the response speed), consideration must be given to making the effect of the former even greater.

In the second embodiment shown in FIGS. 4 and 5, the heat conductive piece 21
The temperature-sensitive members 21 and 22 are respectively fixed to both sides of the crystal resonator 1 so that the temperature-sensitive members 4 and 224 are at the same position on both sides of the crystal resonator 1.
The fixing positions of the temperature sensing members 21 and 22 may be set so that they are alternately located.In addition, in the second embodiment, the heat conductive pieces 214 and 224 are set to be longer, and when used, the above-mentioned heat conductive piece 214,
224 so that it can be set to an appropriate length, it is possible to obtain a temperature sensor whose response speed can be set according to the application after manufacturing.

FIGS. 6 and 7 show specific structural examples of the support structure of the temperature sensor and the electrical signal lead-out lead according to the embodiment described above. Although the shape of the temperature-sensitive member portion is shown in FIGS. 6 and 7 in accordance with the shape of the first embodiment, it is possible to adopt the same structure in the second embodiment. it is obvious. In Figures 6 and 7,
215, 225 are support columns, 216, 226 are conductive paths,
217 and 227 are connection terminals, 115 is a conductive band, and other symbols are the same as in the first embodiment.

FIG. 6 shows an example of a structure in which the temperature sensing members 21 and 22 are made of a non-conductive material or a conductive material whose electrical resistance is large enough to affect the derived electrical signal.

The support struts 215 and 225 are constructed by extending leg-like struts from the joints 212 and 222 of the temperature-sensitive members 21 and 22,
Connecting terminals 217 and 227 are formed at their tips with a width narrower than that of the support columns 215 and 216.

The conductive paths 216 and 226 are electrical signal derivation paths 113 and 1 when the temperature sensing members 21 and 22 are joined to the crystal resonator 1.
A highly conductive metal such as gold is vapor-deposited over the joint parts 212 and 222 where the crystal resonator 1 and the temperature-sensitive member 21, Electrode 1 when integrated with 22
11, the lead-out path 113, the conductive path 216, the electrode 112, the lead-out path 114, and the conductive path 226 are electrically connected to each other.

In this way, electrical signals (electrical vibrations) generated at the electrodes 111 and 112 are extracted to the outside. In addition, when mounting this temperature sensor on a device, for example, connect the connecting terminal 2 to the wiring hole of the printed wiring board that constitutes the measurement circuit.
17, 227 and connect the conductive pattern and connection terminal 217,
227, the temperature sensor becomes the support column 215,
The crystal resonator 1 is supported on a printed wiring board at 225, and the electrical signal generated by the crystal resonator 1 is transmitted to the measurement circuit via conductive paths 216, 226 formed on the support columns 215, 225.

FIG. 7 shows an example of a structure in which the temperature sensing members 21 and 22 are made of a highly conductive material, and in this example, the temperature sensing members 21 and 22 also serve as members for deriving electrical signals.

Support struts 215, 225 and connection terminals 217 at their tips
, 227 are constructed similarly to the structural example shown in FIG.
In the example shown in FIG. 7, the support columns 215, 225 themselves form a conductive path for electrical signals, and the conductive paths 216, 226 as shown in FIG. 6 are not formed on the support columns 215, 225. A conductive band 115 is formed around the periphery of the crystal resonator 1, integrally with the electrode 111 and the lead-out path 113 (in a state where they are electrically connected).

The conductive band 115 is formed, together with the electrode 111 and the lead-out path 113, by depositing gold, for example. Note that electrodes, lead-out paths, and conductive bands are similarly formed on the back side of the crystal resonator 1 shown in FIG. 7 (the side facing the temperature-sensitive member 22). The temperature sensing members 21 and 22 are closely fixed to both surfaces of the crystal resonator 1 on which the conductive bands 115 are formed as described above.

As a result, the joint portions 212, 22 of the temperature sensing members 21, 22
2 comes into contact with the conductive band 115, the temperature sensing members 21, 22 and the electrodes 111, 112 are electrically connected, and the electric signal generated in the vibrating part of the crystal oscillator 1 is transmitted to the support column 21.
5,225. According to the structure shown in FIG. 7, since a conductive band 115 made of a vapor-deposited metal film is formed around the periphery of the crystal resonator 1, the crystal resonator 1 and the temperature-sensitive members 21 and 22 can be joined by soldering or the like. This can be easily done by

In addition, in the structure shown in FIG. 7, the support columns 215 and 225 are formed in the shape of open legs, but this is because the crystal resonator 1 is generally formed extremely thin, so consideration is given to mounting the temperature sensor on a printed wiring board, etc. This is the configuration adopted.

Note that in the configuration of the second embodiment, the heat conductive piece 214
, 224 can be used as a support column for the temperature sensor and a conductive path for electrical signals.

The temperature sensor according to the present invention has a crystal resonator with a diameter of about 51! It is possible to realize a diameter of lφ to 1211φ.

In addition, the temperature sensor according to the present invention can be mounted on a flying vehicle such as a radiosonde in the upper atmosphere due to its characteristics such as being small and lightweight, having a fast response speed, and having a small heat capacity of the temperature sensor itself. Although this temperature sensor is most suitable for meteorological observation that measures temperature from time to time, it can also be used for various other temperature measurements, especially for measuring the temperature of gases.

As explained above in detail, the temperature sensor according to the present invention employs a mechanism that converts changes due to the temperature of the temperature sensing member into changes in the frequency of the crystal oscillator with high measurement accuracy. An extremely reliable temperature sensor can be obtained.

(8) By forming the temperature sensing member into a dome shape, stress caused by changes in the temperature sensing member is applied evenly to the periphery of the crystal resonator, so a temperature sensor with good linearity of the detection signal can be obtained.

(C) A uniaxial rotating type crystal diaphragm, such as an AT cut plate, which is easy to cut from the crystal and has a high yield, can be used as the crystal diaphragm, so a temperature sensor with low cost and high productivity can be obtained. It will be done. By selecting the material, shape, etc. of the temperature-sensitive member, it is possible to easily obtain a temperature-sensitive member with sensitivity suitable for various uses.

(Since a member with high thermal conductivity and small heat capacity is used in the temperature sensing part D, the response speed can be fast. (G) Depending on the embodiment, a member fixed to the crystal resonator ( Since the electrical signal lead-out path and the support means can be constructed using the temperature-sensitive member, the construction can be made simple.

(G) Since the temperature to be measured can be determined by the vibration frequency, the measured value can be detected as a digital signal without the need for a complicated electric circuit, such as an A-D converter circuit, which is extremely useful for computer processing of data. be.

The present invention has various advantages such as, and the present invention has extremely significant effects.

Note that depending on the type of printing used, the present invention may be practiced even if the temperature-sensitive member is fixed to one side of the crystal resonator.

[Brief explanation of the drawing]

The drawings are all drawings showing embodiments of the present invention, and the first
Figures 2 and 3 are respectively a plan view and a front view of the first embodiment, and a sectional view taken along A-A in Figure 1, and Figures 4 and 5 are respectively of the second embodiment. The plan view and BB sectional view in FIG. 4, and FIGS. 6 and 7 are exploded perspective views showing examples of a temperature sensor support structure and an electric signal derivation lead structure according to the first embodiment. It is a diagram. [Main symbols], 1...Crystal resonator, 111, 1
12... Electrode, 115... Conductive band, 2
1, 22... Temperature-sensitive member, 211, 221...
...Temperature sensing part, 212, 222...Joint part, 2
13,223...Air hole, 214,224...
...Heat conduction piece, 215, 225...Support strut, 2
16,226... Conductive path.

Claims (1)

[Scope of Claims] 1. A crystal resonator whose vibration frequency has a cutting angle that has low temperature dependence and high stress dependence, and a crystal resonator that has higher thermal conductivity than the above crystal resonator and that has a thermal expansion coefficient similar to that of the above crystal resonator. What is claimed is: 1. A temperature sensor comprising a temperature-sensing member formed in a dome shape with members having different ratios, the temperature-sensing member being fixed to the periphery of the crystal resonator at its hem. 2. The temperature sensor according to claim 1, wherein the crystal resonator is an AT cut plate. 3. The temperature sensor according to claim 1, wherein the temperature sensing member is fixed to both sides of a crystal resonator, sandwiching the temperature sensing member therebetween. 4. The temperature sensor according to claim 1 or 3, wherein the temperature sensing member has a spherical curved surface. 5. The temperature sensor according to claim 1, 3, or 4, which has a heat conductive piece on the periphery of the bottom portion of the temperature sensing member. 6. The temperature sensor according to any one of claims 1 and 3 to 5, wherein a support strut is integrally formed with the temperature sensing member. 7. The temperature sensor according to claim 6, wherein the support strut is an electrical signal derivation section.