RU2155442C1 - Quartz-crystal resonator with internal thermostatic control - Google Patents

Abstract

FIELD: radio electronics. SUBSTANCE: resonator has evacuated case with base mounting transistor on metal plate and contact lugs carrying crystal piezoid with exciting electrodes deposited onto the latter; it also has heater and temperature transmitter. Base is made in the form of metal ring with case-to-ring fastening points possessing low heat conductance. Mentioned fastening points through which supporting metal ring is secured within case and those through which metal plate is attached to supporting ring are made in the form of insulators accommodating metal rods. Evacuated case inner surface is metallized. Turning-on thermostatic control system ensures fast resonator heating by transistor due to its small mass and adequate heat transfer between heater, piezoid, and temperature transmitter. EFFECT: reduced warm-up period, improved temperature stability of frequency. 3 cl, 6 dwg

Description

 The invention relates to the field of electronics and can be used in frequency stabilization devices.

 A known quartz resonator with an internal temperature control system containing a piezoelectric plate placed in an evacuated housing with exciting electrodes deposited on it, as well as a film heater and a temperature sensor used to statically plate the plate at a given temperature (see. Reference "Piezoelectric resonators". Edited by P. E. Kandyba, P.G. Pozdnyakova, M .: Radio and communications, 1992, p. 362 - 364).

 This resonator has a short time to establish the frequency from the moment of switching on, which is due to the placement of the heater directly on the piezoelectric element. The disadvantage of this resonator is the significant temperature instability of the frequency, which is a consequence of the presence of thermal gradients on the piezoelectric element due to the intense heat flux from the heater located directly on the piezoelectric element into the environment through the piezoelectric element mounting system.

 Of the known devices closest to the claimed is the resonator according to the patent of the Russian Federation N 2101854, IPC H 03 H 9/19, issue. 01/10/98, containing a vacuum housing in which there is a dielectric ring with contact petals located on it, in which a piezoelectric element is mounted with a film heater and a temperature sensor deposited on it, as well as a transistor mounted on a metal plate that is mounted on a dielectric ring in the gaps between the contact petals and the fixing points of the dielectric ring in the evacuated housing. The conclusions of the exciting electrodes of the piezoelectric element are connected to the oscillator circuit; the outputs of the transistor, heater and temperature sensor are included in the thermal control circuit.

 Due to the placement of a transistor inside the resonator, which dissipates significant power in the stationary thermal mode, which causes additional heating of the resonator volume, a significant decrease in the heat flux from the film heater to the environment is achieved through the fastening of the piezoelectric element, which sharply reduces the temperature gradients along the piezoelectric element and increases the temperature stability of the resonator frequency. The metal plate on which the transistor is located has a high thermal conductivity, which leads to rapid heating and, therefore, a short time to establish the frequency. This design is taken as a prototype.

 However, such a resonator is characterized by low mechanical strength of the fastening of the dielectric ring in the evacuated housing, as well as the fastening of the metal plate to this ring. In practice, fixing the plate to the ring is carried out only by gluing, and the area and thickness of the adhesive layer are large enough and do not lend themselves to reliable control, ensuring the identity of this operation from sample to sample. In addition, it is practically impossible to avoid the presence of air microcavities in the adhesive layer, which lead to unpredictable burning of the adhesive layer in the evacuated cavity of the resonator during operation in the apparatus and a sharp deterioration in vacuum, which in turn leads to a sharp increase in heat loss, a decrease in temperature and long-term frequency stability . All the advantages of the resonator are thus lost.

 A dielectric ring with its attachment points is difficult to manufacture, be it ceramic or glass. Making it from ceramics requires sophisticated technological equipment to reproduce the dimensions with the accuracy necessary for a highly stable product, such as a resonator, and making a ring with the necessary fasteners is extremely inefficient due to the low strength and high likelihood of chips and cracks. The accuracy of reproducing the dimensions of the ring and the dimensions of the design of the resonator is generally low, which leads to an unacceptable variation in the parameters of the resonators.

 These shortcomings make the described prototype unsuitable for mass production because of its complexity and low yield, as well as extremely unreliable for use in modern highly stable reference generators.

 The problem to which this invention is directed, is to create a resonator devoid of the disadvantages inherent in the prototype.

 The technical result that the implementation of the present invention provides is to reduce the settling time of the resonator frequency at low power consumption and high temperature stability of the frequency; in increasing the mechanical strength of the resonator, its manufacturability and operational reliability.

 The problem is solved in a quartz resonator containing a vacuum housing, inside of which a support base made in the form of a ring with fastening places located on it in a vacuum housing is fixed, and on a support base there is a metal plate with its fastening places to the support base and a transistor placed on it for regulating the heating current, as well as a quartz piezoelectric element mounted on contact petals and equipped with exciting electrodes applied to it, cm and a temperature sensor. According to the invention, the support base is made of metal, and the indicated mounting points of the support base in the housing and the mounting points of the metal plate on the support base are made in the form of dielectric insulators in which the metal rods are placed. The evacuated housing is provided with metallization of at least part of the inner surface.

 Contact petals can be made as part of the specified metal plate. Contact tabs can also be attached to the support ring.

Next will be given a detailed description of one embodiment of the invention with reference to the drawings, which depict:
in FIG. 1 - resonator design (without internal connections);
in FIG. 2 is a top view of the structure (without housing) for the first embodiment of the piezoelectric element;
in FIG. 3 is a top view of the structure (without housing) for the second embodiment of the piezoelectric element;
in FIG. 4 is a view along arrow A in FIG. 1;
in FIG. 5 is an enlarged view of a fragment of a metal support ring with a dielectric insulator and a rod;
in FIG. 6 is a diagram for including a resonator in a generator with a temperature controller.

 Information confirming the possibility of carrying out the invention.

 The resonator (Fig. 1-5) contains a vacuum case 1, in which a base 2 is fixed with a transistor 3 mounted on it, mounted on a metal plate 4, and contact tabs 5, in which a quartz piezoelectric element 6 is installed with exciting electrodes 7 applied to it, a heater 8 and a temperature sensor 9. The base 2 is made in the form of a metal support ring (for example, from 47ND or 29NK alloy) with its mounting points in the evacuated housing 1. Mounting places of the supporting metal ring the housing and the mounting points of the metal plate 4 on the support ring (Figs. 5-6) are made in the form of dielectric (for example, glass) insulators 10 in which metal rods (for example, from 29NK alloy) are placed 11. The vacuum housing 1 is provided with metallization 12 of the inner surface.

 The leads of the exciting electrodes 7 are connected to the circuit of the oscillator 13, as shown in FIG. 3; the outputs of the transistor 3, heater 8 and temperature sensor 9 are included in the temperature control circuit 14.

 The resonator with internal temperature control works as follows. When a supply voltage is applied, the oscillator circuit 13 through the electrodes 7 excites the oscillations of the piezoelectric element 6, and the temperature control system 13, due to the temperature sensor resistance 9 not matching the value corresponding to the static temperature, opens the transistor 3, which regulates the current through the film heater 8, causing a rapid heating of the piezoelectric element 6. After reaching on the piezoelectric element 6 of a given temperature, the temperature control system 13 locks the transistor 3, and almost all the power is dissipated in it, causing thallic plate 4. As a result, the transition process in the resonator is significantly accelerated, which leads to a significant reduction in the time to establish the frequency. At the same time, heat losses remain insignificant, because the heat flux from the thermostatically controlled part of the resonator (a piezoelectric element mounted on a metal ring) to the environment passes through the fasteners of the metal plate in the evacuated casing, which have low thermal conductivity, and the heat flux from the piezoelectric element by radiation is minimized by metallization of the inner surface of the resonator body.

 The development of serial production technology and testing were carried out on the resonator in a vacuum evacuated glass case with a diameter of 19 mm and a height of 28 mm. A metal ring 2, made of alloy 47ND with dielectric insulators made of C48-2 glass, is fixed inside the case. On the metal (from alloy 29 NK) rods of the ring intended for installing the piezoelectric element, contact (nickel) petals 5 are welded in which a piezoelectric quartz lens is mounted at a frequency of 10.0 MHz (3rd harmonic, SC cut). Exciting silver electrodes 7, a nickel film heater 8, and a temperature sensor (thermistor) 9 are applied to the surface of the lens. The metal (copper with nickel coating) plate 4 is mounted on two pairs of insidious (29 NK alloy) terminals through glass insulators placed with two sides of the rods of the ring, used to mount the piezoelectric element. The transistor 3 is soldered to the copper plate 4. The inner surface of the housing is aluminized. The settling time of the frequency of such a resonator is about 30 s.

 To test the effectiveness of this technical solution and confirm its advantages over the prototype, samples were also made with a dielectric ring made of C48-2 glass, to which a metal plate was glued, on which a transistor was also installed using glue.

A comparison of the parameters showed that:
- the time to establish the frequency of the prototype ~ 20% more;
- long-term frequency stability is much worse due to the disadvantages of the prototype described above;
- the temperature stability of the frequency and power consumption are almost the same, however, the spread of these characteristics from sample to sample is much greater in the prototype.

 The metallization efficiency of the inner surface of the resonator housing was also tested. It turned out that without metallization, the temperature stability of the frequency is more than 2 times worse, which is caused by a sharp increase in temperature gradients on the piezoelectric element due to an increase in the heat flux by radiation from it into the environment. For the same reason, power consumption has increased by ~ 40%. Thus, without plating the housing, the benefits are not realized.

 It should be noted that the advantages of this invention in terms of manufacturability, suitability for mass production and reliability have been fully confirmed.

Claims (3)

 1. A quartz resonator with internal temperature control, containing a vacuum housing, inside of which a support base made in the form of a ring with fastening places located on it in a vacuum housing is fixed, a metal plate is installed on the support base with its fastening places to the support base and a transistor placed on it for regulation of the heating current, as well as a quartz piezoelectric element mounted on the contact petals and equipped with excitation electrodes applied to it, heating a body and a temperature sensor, characterized in that the supporting base is made of metal, and the indicated mounting points of the supporting base in the housing and the mounting points of the metal plate on the supporting base are made in the form of dielectric insulators in which metal rods are placed, while the evacuated housing is provided with metallization at least least part of the inner surface.  2. The quartz resonator according to claim 1, characterized in that said contact petals are made as part of said metal plate.  3. The quartz resonator according to claim 1, characterized in that said contact petals are mounted on a support ring.

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