DE8701634U1 - Temperature-sensitive quartz oscillator - Google Patents

Description

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HahaU* 27, January 1987 ZPi/-Ga/gr/Öi99F

Heraeus GmbH

Utility model application

"Temperature-sensitive quartz oscillator"

The innovation concerns a temperature-sensitive quartz oscillator with at least two parallel surfaces of approximately the same size* which form a predetermined intersection angle with an x-y-z coordinate system of the quartz crystal formed by an electrical, mechanical and optical axis, whereby the angle enclosed by one of the two surfaces and the electrical (x) axis lies within a tolerance range including the angle 0°.

A temperature-sensitive quartz is known from US-PS 3,486,023 which has a high temperature coefficient due to the so-called y-cut. Y-cut means here that the cut runs through the so-called y-plane, which is spanned by the x and z axes; this means that the angle enclosed by the cut surface and the electrical x-axis is 00°, this also applies to the angle enclosed by the cut surface and the optical z-axis. * Since in the range 0=0 the difference quotient formed from the temperature coefficient change per angle change is relatively large, in order to clearly assign the generated frequency to the temperature, the cut must be as precise as possible within a very narrow tolerance range; otherwise the dependence of the frequency on the temperature would have to be determined for each individual quartz before it is used.

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Wettening has set itself the task of creating quartz oscillators, in particular of the thickness oscillator type, with the largest possible temperature coefficient, whereby the smallest possible variation between specimens should occur in series production.

The problem is solved according to the invention by the characterizing features of claim 1.

In a preferred embodiment, the surfaces parallel to one another are circular, with the centers of the two circular surfaces lying on a common axis that passes through them perpendicularly, and the casing located between the two surfaces having an outward-facing bulge that extends over its entire circumference.

The innovation has proven to be advantageous in that quartz oscillators, particularly those produced in mass production, can be manufactured within a technically easy-to-manage tolerance range with a practically constant temperature coefficient, so that temperature sensors equipped with such quartz can be connected to specified evaluation units after a single-point calibration or zero-point calibration; the easy exchangeability of temperature sensors is particularly advantageous.

The subject of the innovation is explained in more detail below using Figures 1 to 3.

Figure 1 shows the cutting plane of the surface in the crystalline structure of the quartz indicated by coordinates; Figure 2a shows a quartz oscillator with circular surfaces, while Figure 2b shows a cross section through the quartz. Figure 3a shows a quartz oscillator with segmented circular surfaces, the geometric relationships being explained using Figure 3b.

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According to Figure 1, the x-axis of the coordinate system corresponds to the electrical axis, the Y'-axis to the mechanical axis and the z^-axis to the optical axis of the crystal structure of the quartz. The intersection angle enclosed by the plane of the surface 2 of the quartz and the x-axis is between 1 and *-1°, while the angle 0 enclosed by the plane of the surface 2 and the z-axis is in the range from 3 to 6° or in the range from 68 to 72°; preferably the sennite angle is between 15* and -15*, while the angle © is in the range from 4° 8* ~3· or in the range from 70° ~3'. The temperature coefficient is at a maximum in the range from 0 to 4°, whereby even intersection angles slightly above or below the value of 4° only show an extremely slight change in the temperature coefficient; Furthermore, the temperature coefficient has a pronounced minimum in the range of 0*70°, so that in this range there is also a tolerance zone with extremely small changes in the temperature coefficient; between these two angles there is a zero crossing of the function of the temperature coefficient at © ^30°, i.e. at this point temperature changes have no influence on the oscillation behavior of the quartz.

According to Figure 2a, the quartz has two circular, flat surfaces 2, which are arranged axially to one another. Between the two surfaces there is a faceted surface 3 extending over the entire circumference, which is intended to achieve a high quality of the quartz oscillator. The faceting consists of a circumferential, trapezoidal bulge, whereby the cross section according to Figure 2b is represented as a broad octagon. The quartz 1 has a diameter of approx. 4.5 mm and a thickness of approx. 0.1 mm; the frequency is 16.75 niHz ~50 kHz at a temperature of 25 °C, whereby a quality of at least 5000 is achieved.

For use as a temperature sensor, the surfaces 2 are provided with silver electrodes 5 by mass vapor deposition. The electrodes 5 overlap in a circular manner inside the disk and have lateral projections 6 on several sides to ensure lateral contact by the clamping springs (not shown here) located in the temperature sensor housing. The electrodes 5 are shown disproportionately in Figure 2b for the sake of a better overview. The quartz is held in the clamping springs by high-temperature conductive adhesives; the quartz is surrounded by a

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The stainless steel housing is surrounded by an air-tight protective gas atmosphere. The outside of the stainless steel housing is smooth and therefore suitable for industrial temperature measurement technology. The housing base and the connecting pipes are laser welded, with the housing base containing two die -cast leadthroughs for connection pins. The clamping springs inside the housing are connected to the connection pins by spot welding.

The aro^'icsoer'icn of the system lies Dex temperatures between -hu and &tgr;&ogr;&ugr;&ugr; -c

Another form of quartz 1 is shown in Figure 3a; the surfaces 2 have the shape of segmented circles according to Figure 3b, with two secants 2' lying opposite each other and running parallel. Due to the segmentation, this quartz has a similarly high quality to that described in Figure 2, whereby faceting of the outer surface 4 can be dispensed with. The electrode application and mounting in the temperature sensor housing correspond to the embodiment explained in Figure 2.

Claims (5)

&bull; · Hanau. 27 January 1987 ZPL-Ga/gr/0199F W-C. Heraeus GmbH Utility model application "Temperature-sensitive quartz crystal" Protection claims 1. Temperature-sensitive quartz oscillator with at least two mutually parallel surfaces of approximately the same size, which form a predetermined intersection angle with an xyz coordinate system of the quartz crystal formed by an electrical, mechanical and optical axis, wherein the angle Q enclosed by one of the two surfaces and the electrical (x) axis lies within a tolerance range including the angle 0°, characterized in that the tolerance range of the angle Q lies between +1° and -1° and that the angle θ enclosed by one of the surfaces and the optical (z) axis lies either in the range from 3 to 6° or in the range from 68 to 72°. 2. Quartz oscillator according to claim 1, characterized in that the mutually parallel surfaces (2) are circular and arranged axially to one another, the centers of the two circular surfaces lying on a common axis passing through them perpendicularly. ti 'ti 4* 4 tons · 3. Quartz oscillator according to claim 2, characterized in that the jacket surface (3) located between the two surfaces in the region of the middle of the distance between the two surfaces has an outwardly directed bulge (3 ¹ ) extending over its entire circumference. 4. Quartz crystal according to claim 3, characterized in that the bulge (3 ¹ ) is trapezoidal. 5. Quartz oscillator according to claim 1, characterized in that the surfaces (2) are designed as segmented circles with opposing, parallel secants (2') which are congruent to one another. K 111) K I Ii llllt II I IIII I < · I* I 1411 6*4 It· Il IaI ItIlI III 1114* I