JPS593884B2 - crystal oscillator unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a specific structure for canceling changes in the natural frequency of a crystal resonator due to temperature.

An object of the present invention is to correct temperature changes in vibration frequency with a simple structure by using both a capacitor for temperature compensation and a stand for fixing the vibrator.

First, a conventional example will be explained.

A tuning fork-shaped crystal resonator formed from a thin crystal plate using photoetching technology is very suitable for use in wristwatches because it is suitable for mass production and is compact.

Although there are various methods for cutting out the vibrator at an angle with respect to the crystal axis and arranging the electrodes, the methods shown below are particularly excellent from the viewpoint of temperature characteristics and dynamic impedance.

FIGS. 1 and 2 are conceptual views of this vibrator from the front and back sides.

The vibrator 1 is extracted from the crystal plate shown in FIG. 3 using a photoetching technique.

The angle γ in the figure is taken in the range 0° to 10°.

Reference numbers 2 and 3 in FIG. 1 and 4 and 5 in FIG. 2 are electrodes for applying an electric field to the vibrator.

The vibrator 1 includes a metal film 8, which is attached to the upper surface of a fixing base 10 made of an insulating material by vapor deposition, sintering, etc., in accordance with the electrodes 6, 7 of the vibrator, using parts 6, 7 of the back electrodes 4, 5. 9
electrode 2 and electrode 3 are bonded to the wire 11.1
2 are connected to electrode terminals 13 and 14, respectively.

FIG. 4 is a diagram showing the arrangement of electrodes of this vibrator.

The electric field is parallel to the X-axis (t) as shown by the arrow in the figure, so the dynamic impedance is very small, and the temperature (To) at which zero temperature coefficient of the frequency-temperature characteristic is obtained can be changed by changing the angle 2 without changing impedance
It can be freely changed within the range of 0°C to 40°C.

Figure 5 shows the relationship between the frequency of the oscillator mentioned above and the temperature, and it is clear from this that if this oscillator is used in a watch, it will not work when the temperature is high or low. It has the disadvantage of causing a ``lag'' in the process.

Below, we will describe a method to eliminate the drawbacks associated with this temperature change.

Figure 6 shows a widely known oscillation circuit for a crystal resonator, in which 15 is a resonator, 16 is an inverter circuit, and 1 is an inverter circuit.
γ and 18 are capacitors, and 19 and 20 are resistors.

FIG. 7 shows the relationship between the capacitance (horizontal axis) of the capacitor 17 or 18 in FIG. 6 and the frequency (vertical axis - arbitrary scale).

Figure 8 shows how temperature changes in vibration frequency are canceled out by using a dielectric material such as barium titanate whose permittivity changes with temperature as the capacitor 17.18. The temperature-frequency relationship shown in the figure is drawn, and the capacitance-frequency relationship shown in FIG. 7 is drawn in the second quadrant.

Note that the vertical axes of the first and second quadrants have opposite directions.

The fourth quadrant shows the relationship between the capacitance and temperature of the correction capacitor 17 or 18.

If the capacitance-temperature characteristic in the fourth quadrant is taken appropriately, the frequency-temperature characteristic before correction shown by the solid line in FIG. 9 is relaxed as shown by the broken line.

FIG. 10 shows a specific conventional example of the circuit shown in FIG. 6, in which 23 is a resonator case, 21° and 22 are temperature compensation capacitors, and 24 is an IC.

25, 26, and 27 are power supply and output terminals. As is clear from this conventional example, the two capacitors 21 and 22 occupy a considerably large volume compared to other parts.
It has disadvantages such as complicated wiring etc.

As described below, the present invention aims at simplifying and downsizing the entire crystal resonator unit by housing at least one of these two capacitors in a resonator case.

FIG. 11 shows an embodiment of the present invention.
．． Reference numeral 29 denotes a block-shaped capacitor, which has electrodes formed on its upper and lower surfaces, the lower surface being adhered to a substrate 30, and the vibrator 15 being adhered to the upper surface.

The electrical connection between them is as shown in FIG. 12, and the circuit shown in FIG. 6 is obtained.

In addition to this, there are two types of capacitor electrode shapes as shown in Figure 13.
Both electrodes may be formed on the top surface, and the capacitors 31 and 32 themselves may be mounted insulated from the substrate 30.

Furthermore, it is also possible to give only one of the two blocks the property of a capacitor, and use an insulator such as glass or ceramic for the other block.

Note that the specific circuit for temperature compensation is not limited to that shown in FIG. 6; for example, a capacitor may be inserted in series with the vibrator 34 as shown in FIG. 14.

Here, the capacitance of at least the capacitor 39 among the capacitors 33, 38, and 39 changes depending on the temperature.

37 is an inverter, and 35 and 36 are resistors.

Their connections are as shown in Figure 15.

In the figure, capacitors 33 and 39 are used as stands.

In this case as well, temperature compensation is performed in the same manner as described above by changing the capacitance of the capacitor 39 due to temperature.

Although the present invention has been explained above using a specific tuning fork type crystal resonator shown in FIG. The present invention is not limited to, and may be applied to vibrators with various cutting angles and electrode structures.

For example, in Fig. 16, 40 is a relatively thick vibrator;
Electrodes of two polarities are taken out from the front and back surfaces of the support section 41, respectively.

42 is a capacitor according to the present invention, one electrode of which is bonded to the back surface of the vibrator, and the other electrodes are tangential to the substrate.

43 is a bonding wire connected to the front electrode of the vibrator, 44 is a bonding wire connected to the back electrode of the vibrator, and 45 is a bonding wire connected to the substrate, which are temperature compensated for the reason detailed above. .

As is clear from the above, according to the present invention, by using the fixed support of the crystal resonator and the capacitor of the oscillation circuit, it is possible to achieve a reduction in volume and improve reliability due to the reduction in the number of connection points. Coupled with improvements, the contribution when used in wristwatches is significant.

[Brief explanation of the drawing]

FIG. 1 is a schematic view of an example of a crystal resonator from the front side, and a diagram showing a conventional fixing method. Figure 2 is an overview of the crystal resonator from the back side. FIG. 3 is a diagram showing the cutting angle of the crystal resonator from the crystal original plate, and 1 indicates the crystal resonator. FIG. 4 is a diagram showing the electrode arrangement of the crystal resonator. FIG. 5 is an example of the frequency-temperature characteristic of the crystal resonator. FIG. 6 shows a general vibrator oscillation circuit, where 15 is a vibrator and 17 and 18 are capacitors. FIG. 7 is an example of the capacitance-temperature characteristics of the capacitors 17 and 18 shown in FIG. FIG. 8 is a diagram showing how the temperature change in the oscillation frequency is compensated for by the temperature change in the capacitance of the capacitor. FIG. 9 shows the compensation characteristics of the oscillation frequency for temperature changes, where the solid line shows the characteristics before compensation and the broken line shows the characteristics after compensation. FIG. 10 shows a conventional mounting example of the circuit shown in FIG. 6, in which 23 is a resonator case, and 21 and 22 are temperature compensation capacitors. 11 and 12 show an embodiment of the present invention, in which a vibrator 15 is mounted across capacitors 28 and 29 according to the present invention. FIG. 13 shows another embodiment of the present invention, in which a vibrator 15 is mounted across capacitors 31 and 32 according to the present invention. FIG. 14 shows another example of a vibrator oscillation circuit, where 34 is a vibrator;
39 is a capacitor. FIG. 15 shows an embodiment of the circuit shown in FIG. 14, in which a vibrator 34 is mounted across capacitors 33 and 39. FIG. 16 shows another embodiment of the present invention, in which a thick vibrator 40
is attached to the capacitor 44 according to the present invention.

Claims (1)

[Claims] 1. In a crystal resonator unit having a tuning fork type crystal resonator, the tuning fork type crystal resonator is fixed to a fixed base made of a dielectric material, and an electrode disposed at the base of the tuning fork type crystal resonator and an electrode on the fixed base are fixed. The dielectric is directly bonded to the electrode, and the dielectric constant of the dielectric is set to a value that changes to cancel out temperature changes in the oscillation frequency of the tuning fork type crystal resonator, and the tuning fork type crystal resonator is further bonded. A crystal resonator unit characterized in that an electrode on a fixed base serves as an electrode extraction terminal of the dielectric.