JPS5856419B2 - temperature sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature sensor using a piezoelectric vibrator, especially a crystal resonator. The present invention relates to a temperature sensor that measures temperature by detecting the vibration frequency of a crystal resonator that is proportional to temperature by applying a force that is proportional to 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
Both methods focus on the fact that the temperature dependence of the crystal oscillator increases depending on its cutting 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.

Compared to temperature sensors using metal resistance wires, thermistors, etc., this temperature sensor using a crystal resonator of an LC cut plate has lower power consumption, measurement accuracy, and ease of detecting electrical signals (direct digital signal detection).

), etc., but the crystal resonator itself does not have good thermal conductivity, so it takes a long time for the crystal resonator to reach the temperature to be measured, so the response speed is slow. .

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 is also a drawback.

Furthermore, a crystal resonator as a temperature sensitive element generally uses an LC cut plate, and an LC cut plate is a biaxially rotating type crystal resonator, and a single axis rotating type crystal resonator, such as an AT cut plate. (This AT cut plate can be used in the present invention.

) has the disadvantage of being less mass-producible than crystal resonators such as

The present invention solves the above-mentioned conventional drawbacks, has a fast response speed,
Another object of the present invention is to provide a temperature sensor using a piezoelectric vibrator (crystal resonator) that can be manufactured with various sensitivities depending on the application and can be mass-produced.

For this purpose, in the present invention, the periphery of two opposing sides of a rectangular (square or rectangular) crystal oscillator, which has low temperature dependence and high stress dependence, has higher thermal conductivity than the crystal oscillator, and A member whose coefficient of thermal expansion is different from that of the piezoelectric vibrator is rigidly fixed, and changes in temperature are converted into thermal expansion of the member, thereby applying stress to the piezoelectric vibrator. The temperature to be measured is determined by changes in the vibration frequency of the piezoelectric vibrator due to stress.

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 leftover member can be changed as appropriate. Furthermore, 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 the drawings are diagrams for explaining the present invention in detail, and the first
The figure is a plan view, FIG. 2 is a sectional view taken along the line B-B shown in FIG. 1, and FIG. 3 is a perspective view.

Furthermore, FIG. 4 is a custom diagram of the stress sensitivity coefficient for the AT cut plate of the crystal resonator.

1 to 3, 1 is a crystal resonator, 11F and 112 are electrodes, 113 and 114 are electrical signal output paths, 21j, - and 22 are temperature sensing members, 212, 213.
222 and 223 are joint parts 214, 215, 224 and 225 are heat conducting pieces, 31 and 32 are electrical signal lead-out leads, and 41 and 42 are protective covers.

The crystal oscillator 1 has a characteristic that the change in its vibration frequency due to changes in ambient temperature is extremely small, and the vibration frequency changes in proportion to the applied stress, that is, the temperature dependence of the vibration frequency is An angle that is low and has a high stress dependence is used.

Specifically, a crystal resonator having such characteristics includes an AT-cut plate of l-axis rotation type, but other crystal resonators with various cutting angles can also be used.

The crystal resonator 1 has electrodes 111 and 112 on both surfaces, for example, by gold plating, and lead-out paths 113 and 114 for extracting electrical signals from the electrodes 111 and 112. The lead-out paths 113 and 114 are provided in the same way as the child).
Electric signal derivation leads 31 and 32 are connected to the terminals.

The temperature sensing 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 metal such as aluminum or silver, and are positioned parallel to each other on one plane. A pair (two strips) of protruding strip-shaped joints 2 provided in
12, 213, 222-f-= and 223 on the other plane.
It has heat conductive pieces 214, 215, 224 and 225 in the form of protrusions, respectively, which are provided in a direction perpendicular to the setting direction of 23, and are formed into a rectangular shape (square or rectangle).

The crystal resonator 1 is sandwiched between the two temperature-sensitive members 21 and 22 at their joints 212, 213, 222 and 223, and is rigidly fixed by appropriate means.

The crystal oscillator 1 and the temperature-sensitive members 21 and 22 are fixed together in such a way that changes in the external shape (expansion or contraction) of the temperature-sensitive member due to temperature changes are effectively transmitted to the crystal oscillator 1 at the fixed portion. It is firmly fixed to prevent any burrs from forming.

As a result, a space is formed between the electrodes 111 and 112 of the crystal resonator 1 and the temperature sensing members 21 and 22.

The part where the electrodes 111 and 112 are formed is the vibrating part of the crystal resonator 1, and this vibrating part is separated from the temperature sensing members 21 and 22 by the above-mentioned space, and the vibration of the crystal resonator 1 is inhibited. Care has been taken to ensure that this does not occur.

In addition, the temperature sensing member 21.22 is connected to the joint portion 212°213.2.
22 and 223 are fixed to the crystal resonator 1 on two opposing sides of the crystal resonator 104, and the remaining two sides are left open and fixed to the crystal resonator 1 for measurement. A flexible protective cover 41 is placed over the above-mentioned open part to prevent the user from coming into contact with the atmosphere in which the user intends to use the product, and to protect it from floating dust.
j=- and 42 (having flexibility to the extent that it does not affect the deformation of the temperature-sensitive members 21 and 22 due to temperature changes).

Since the protective covers 41 and 42 are flexible, the air existing in the space in which the crystal resonator 1, the temperature sensing members 21 and 22 and the flexible protective covers 41 and 42 are formed. When the crystal oscillator 1 expands or contracts due to changes in ambient temperature or atmospheric pressure, there is almost no effect on the vibration frequency of the crystal resonator 1.

When the temperature to be measured rises, the temperature sensing members 21 and 22 expand.
A force in the direction shown by arrow F1 in the figure, that is, a stretching force acts, and when the temperature to be measured falls, the temperature sensing members 21 and 22 contract, and a force in the direction shown by arrow F2 in FIG. 1 is applied to the crystal resonator 1. , that is, a compressive force acts.

Since the vibration frequency of the crystal oscillator 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.

Figure 4 shows how the stress sensitivity coefficient changes depending on the direction of the force applied to the crystal oscillator of the AT cut plate. According to this characteristic, the crystal oscillator of the AT cut plate has angles of 0° and 1800 with respect to the X axis. It can be seen that the stress sensitivity coefficient becomes maximum when a load is applied in the direction, and becomes minimum at 90°.

The force Fl is determined by taking advantage of the characteristic that the stress sensitivity coefficient changes depending on the direction of the load applied to the crystal resonator.

Temperature sensors with various sensitivities can be obtained by appropriately setting the angle between the direction of F2, that is, the direction in which the temperature sensing members 21, 22 contract or expand due to temperature changes, and the X axis of the crystal resonator 1.

Further, the temperature sensing members 21 and 22 expand or contract in the direction of the force that should be applied to the crystal resonator 1 due to temperature changes, and also expand or contract in the direction perpendicular to the direction of the force.

The expansion or contraction of the temperature-sensitive members 21 and 22 in the direction perpendicular to the direction of the force has a considerable effect on the sensitivity of the frequency change to the stress of the crystal resonator 1, so the expansion or contraction in the perpendicular direction is as described above. It is better that the force be smaller than the expansion or contraction in the direction of the force that should be applied to the crystal resonator 1.

For this reason, the shape of the crystal oscillator 1 should be made into a rectangle with the long side in the direction in which the force is applied, or the joint portion 212° 213, 222, 2 of the crystal oscillator 1 and the temperature sensing member 21.
It is effective to limit the fixed portion 23 to a length corresponding to the electrodes 111 and 112 (vibrating portion) formed on the crystal resonator 1.

Further, the shape of the temperature sensing members 21.22 is the same as that of the joint portion 212.
213, 222, and 223, this increases the area where the temperature sensing part of the temperature sensor comes into contact with the atmosphere to be measured, thereby increasing the response speed of the temperature sensor. It is effective for that.

The thermally conductive pieces 214, 215, 224, and 225 are made of the same material and integrally constructed as the temperature-sensitive member 21.22, thereby increasing the surface area of the temperature-sensitive member 21.22. The time required to reach the ambient temperature (temperature to be measured) of .22 is accelerated.

As a result, a temperature sensor having a faster response speed can be obtained than simply forming the temperature sensing members 21, 22 in a planar shape.

In addition, the heat conductive pieces 214, 215, 224 and 22
5 is a force F1.5 applied to the crystal resonator 1 when the temperature sensing members 21, 22 expand or contract due to temperature changes. It is set in the direction of F2.

By doing this, the heat conductive pieces 214, 21
5° 224 and 225 have the original function of increasing the response speed, and when the temperature sensing members 21 and 22 expand extremely due to a large temperature change, the joints 212 and 22
It also has the secondary effect of preventing the temperature between 2, 213, and 223 from deforming into a curved shape, and as a result, the range of temperature to be measured can be expanded.

When measuring temperature, it is important for accuracy to reduce the amount of heat absorbed from the object to be measured, that is, the heat capacity of the temperature-sensitive members 21 and 22. The sizes of 214°, 215.22t$- and 225, the set number of threads, etc. are determined.

The temperature sensor according to the present invention has 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 where measurements are taken from moment to moment, it can also be used for various other types of temperature measurement, especially gas temperature measurement.

As explained above in detail, the temperature sensor according to the present invention is (4) a crystal resonator used in the temperature sensor, for example, AT
L-axis rotating type like cut plate can be used,
The crystal resonator can be easily derived from the crystal, has a high yield, is suitable for mass production, and can be highly reliable.

(B) By appropriately setting the mounting angle of the crystal resonator to the temperature-sensitive member, sensitivity suitable for various uses can be easily obtained.

(By making the temperature-sensitive member a material with an appropriate coefficient of thermal expansion, it is possible to obtain sensitivities suitable for various uses.

(D) The temperature sensing part has higher thermal conductivity than a crystal oscillator,
In addition, a member with a small heat capacity is used, and its shape is devised so that the temperature sensing part quickly reaches the ambient temperature, so the response speed is faster than that of a conventional temperature sensor using, for example, an LC cut plate. can do.

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

Note that, depending on the application, the present invention may be practiced even with a structure in which 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
FIG. 2 is a plan view, FIG. 2 is a sectional view taken along the line B-B in FIG. 1, FIG. 3 is a perspective view, and FIG. 4 is a stress sensitivity coefficient characteristic diagram of a crystal resonator of an AT cut plate. Explanation of symbols, 1...Crystal resonator, 31.32.
...- Lead-out lead, 111, 112 ... Electrode, 21゜22 ... Temperature-sensitive member, 212, 213
,222゜223...Joint part, 214,215
, 224° 225... Heat conductive piece, 41.42.
・−・Protective cover F1. F2...Compression force.

Claims (1)

[Scope of Claims] 1. A rectangular crystal resonator with a cutting angle whose vibration frequency has low temperature dependence and high stress dependence, and a rectangular crystal resonator with a higher thermal conductivity than the above crystal resonator, and which has a thermal conductivity with the above crystal resonator. It is formed of members having different expansion coefficients, has a rectangular flat plate shape, and has a pair of joint portions in the shape of protrusions parallel to each other on one plane thereof,
and a heat-conducting piece in the form of a protrusion is provided on the other plane in a direction perpendicular to the setting direction of the joint, and the temperature-sensing member has two opposing sides of the crystal resonator. A temperature sensor characterized by being fixed to a joint of a pair of members. 2. The temperature sensor according to claim 1, which is a crystal resonator AT cut plate. 3. The temperature sensor according to claim 1, which is a temperature-sensitive member sandwiching a crystal resonator and fixed to both sides of the crystal resonator. 4. The temperature sensor according to claim 1 or 2, in which the long side of the crystal oscillator is stepped in the direction of the force applied by the temperature sensing member.