JPH11214929A - Piezoelectric oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crystal oscillator which is easily made inexpensive and small, and has excellent frequency stability and rise time characteristic. SOLUTION: Six surface mounted small heaters 4, 4', 5, 5', 6 and 6' are arranged on a printed circuit 1. The small heaters 4, 4', 5 and 5' are adhered closely and fixed between a metallic cap 9 of an oscillator 10 and the circuit 1. Also, the small heaters 6 and 6' are adhered closely and fixed between lead terminals 11 and 11' of the oscillator 10 and the circuit 1 via a metallic piece 8. The six small heaters are connected to a temperature control circuit 3 on the bottom of the circuit 1. A temperature sensor 7 is arranged between the heaters 6 and 6' and is connected to the circuit 3. The six small heaters take into consideration the heat capacity and heat radiation of a quartz oscillator, and respective heating quantity is separately set.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric oscillator,
In particular, the present invention relates to a piezoelectric oscillator having a high oscillation frequency.

[0002]

2. Description of the Related Art In the field of electric equipment such as a frequency counter used for maintenance of communication equipment of a mobile communication base station, a satellite communication device, etc., a crystal oscillator used as a reference transmission source for these is used. Is required to have high frequency stability, so that the frequency stability is generally 1 × 1
A constant temperature oven crystal oscillator of about 0 ^-7 to 1 × 10 ^-10 is used. In recent years, in these fields, there has been a demand for small size, light weight, and portability, and there has been a demand for a thermostatic oven crystal oscillator to be small and light. A constant temperature oven crystal oscillator is configured to house a crystal oscillator in a recess formed in a metal block with a large heat capacity in order to obtain a high stable oscillation frequency, and to further heat the metal block at a predetermined temperature. And had FIG. 3 is a partial sectional perspective view showing an example of a conventional oven controlled crystal oscillator. As shown in the figure, a recess is formed in a metal block (100) made of a metal such as aluminum, and a quartz oscillator (101) is housed in the recess. This crystal oscillator (10
The lead terminal of 1) is connected to the substrate (10) on which the oscillation circuit is formed.
2) is connected by soldering or the like. Also, on the outer peripheral surface of the metal block (100), the metal block (10
A heater wire (103) for heating the heater wire (0) is wound, and a semiconductor element (104) such as a transistor for controlling the power supplied to the heater wire (103) is tightly fixed. Thereby, the semiconductor element (104) can be used as an auxiliary heat source, and the heater wire (10) can be used.
By heating the semiconductor element (104) at a constant temperature by the heating of (3), the characteristics of the semiconductor element (104) are stabilized. Furthermore, (105) is a metal block (10
0) a temperature sensor such as a thermistor for detecting an internal temperature; and (106) a temperature for controlling a heating temperature together with the semiconductor element (104) based on temperature information from the temperature sensor (105). It is a substrate on which a control circuit is configured. (107) is a metal container made of aluminum or the like, and a gap between the metal container (107) is provided with a heat insulating material (10).
8) is filled. The oven controlled crystal oscillator configured as described above causes the heater wire (103) to generate heat under the control of the temperature control circuit (106) to heat the metal block (100) and the crystal oscillator (101) to a specific constant temperature. I do. Thus, the oven-controlled crystal oscillator can output a highly stable frequency signal.

[0003]

[Problems to be solved by the present invention] However, FIG.
Since it is necessary to use a metal block (100) having a predetermined heat capacity in order to maintain the crystal oscillator (101) at a constant temperature,
There has been a problem that the cost of the oscillator increases and the size of the oscillator increases. Also, the lead terminals connected to the crystal oscillator (101) and the substrate (10
Since the heat of the crystal oscillator is radiated in 2), there is also a problem of frequency stability in which the temperature of the crystal oscillator changes suddenly due to the fluctuation of the outside air temperature and the oscillation frequency becomes unstable. Further, after the power is turned on, the heater (103) starts heating.
03) is transmitted from the metal block (100) to the quartz crystal plate via the metal cap of the crystal unit via a long heat transfer path, so it takes a long time for the temperature of the crystal unit to stabilize. This causes a problem that the rise time from turning on the power supply voltage to stabilizing the oscillation frequency becomes long. The present invention has been made in order to solve the above-mentioned problems, and can be easily reduced in cost and size.
Another object of the present invention is to provide a crystal oscillator having excellent start-up characteristics and rise time characteristics.

[0004]

According to the present invention, there is provided an oscillator circuit, a plurality of surface-mount heaters, and a temperature for controlling a heating temperature of the heater. A control circuit is disposed on a substrate, and a case of the piezoelectric vibrator and a lead terminal of the piezoelectric vibrator are simultaneously heated by separate heaters in order to simultaneously heat the piezoelectric vibrator, the oscillation circuit, and the temperature control circuit. It is characterized by doing. According to a second aspect of the present invention, in addition to the first aspect, a ratio of electric power supplied to each heater is set such that an oscillator oscillation frequency is stabilized according to a difference in heat capacity of the piezoelectric vibrator. .

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on illustrated embodiments. 1A and 1B show the structure of a main part of a crystal oscillator according to an embodiment of the present invention. FIG. 1A is a side view, and FIG. 1B is a top view. An oscillation circuit (2) is provided on the lower surface of the printed circuit board (1) shown in FIG.
And a temperature control circuit (3), and six small surface-mount type heaters (4,
4 ', 5, 5', 6, 6 ') are spaced apart from each other. Each of the small heaters (4, 4 ', 5, 5') is tightly fixed between the metal cap (9) of the vibrator (10) and the substrate (1). ) Are tightly fixed between the lead terminals (11, 11 ′) of the vibrator (10) and the printed board (1) via a metal piece (8). The six small heaters (4, 4 ', 5, 5',
6, 6 ') are electrically connected to the temperature control circuit (3). A temperature sensor (7) is arranged on the printed circuit board (1) between the small heaters (6, 6 '), and the temperature sensor (7) is electrically connected to the temperature control circuit (3). ing. Furthermore, a power transistor (1
2) is tightly fixed to the cap (9), and is also used as an auxiliary heat source. Further, if necessary, the periphery of the printed circuit board (1) and components mounted thereon may be covered with a heat insulating material (not shown), or may be stored in a package. The operation of the crystal oscillator having such a configuration will be described. When power is supplied to the crystal oscillator, the oscillation circuit starts oscillating at a frequency based on the resonance frequency of the crystal resonator. On the other hand, the temperature control circuit (3) supplies power to the six small heaters so that the temperature detected by the temperature sensor (7) matches the set temperature. The small heater (4, 4 ',
5, 5 ') heats the metal cap (9), and the quartz plate is warmed by radiant heat from the metal cap (9).
The small heater (6, 6 ′) is connected to the lead terminal (11,
11 ′) is heated, and the quartz crystal plate is heated by the heat directly transmitted from the lead terminals (11, 11 ′). Furthermore, the six miniature heaters heat the printed circuit board (1), while the power transistors (12) also heat the crystal resonator (9). FIG. 2 shows an example of the temperature control circuit (3). In this configuration, the resistance elements R2 and R3 are connected in series, and the center of the connection is connected to the positive input of the differential operational amplifier IC1. The thermistor TH1 serving as a temperature sensor and the resistor R1 are connected in series, and the center of the connection is connected to the minus input of the differential operational amplifier IC1 via the resistor R4. The other terminal of each of the resistance element R2 and the thermistor TH1 is connected to the power supply element IC2, and the other one of the terminals of the resistance elements R1 and R3 is grounded. A feedback resistor R5 is connected between the output of the differential operational amplifier IC1 and the negative input. The transistor TR1
Are connected in series between heater H1 and heater H2, heater H3 and heater H4, and heater H5 and heater H6, which are connected in series. Incidentally, C1 and C3 connected between the collector of the transistor TR1 and the ground and between the power supply element IC2 and the installation are bypass capacitors. The operation of the temperature control circuit (3) shown in FIG. 2 will be briefly described below. The differential operational amplifier outputs a voltage corresponding to a voltage difference between a positive input and a negative input. As the voltage difference becomes lower, the resistance value of the thermistor TH1 becomes higher as the temperature becomes lower, so that the voltage becomes higher. Further, the output voltage of the differential operational amplifier becomes higher and the heater (H1, H2, H3, H3) becomes higher.
4, H5, H6) are each heated. The zener diode ZD1 is for determining the minimum voltage at which the transistor TR1 operates. In such a crystal oscillator, the metal cap (9) of the crystal unit (10) used for the crystal oscillator and the lead terminal portion (11) have different heat capacities and heat radiation amounts. That is, when the metal cap (9) is heated, the main path for heating the crystal plate inside the crystal unit (10) is mainly the path for heating the crystal plate by radiant heat from the metal cap (9). Lead terminal (1
When 1) is heated, the main path is directly transmitted from the lead terminal portion to the quartz crystal plate. Therefore, taking into account the difference in heat capacity and heat dissipation of the crystal unit, a small heater (4, 4 ',
5, 5 ', 6, 6') are individually set, so that the heating efficiency is improved and the temperature of the crystal unit (10) is hardly fluctuated by the influence of the outside air temperature. It is possible. In this embodiment, the quartz oscillator (1
0) metal cap (9) and lead terminal portion (11,
11 ') and small heaters (4, 4', 5, 5 ', 6,
6 ') is described as being in direct contact with or tightly fixed via the metal plate (8), but may be bonded and fixed using an adhesive or the like having excellent thermal conductivity. In the above description, six small heaters are used, but the present invention is not limited to this, and even if the number of small heaters is smaller or larger, the vibrator and the printed board are stably heated. Needless to say, by setting the heating capacities of the individual small heaters so as to perform the same operations as in the present embodiment. Furthermore, in the description of the present embodiment, a thermistor element is used as the temperature sensor (7). However, the present invention is not limited to this, and another semiconductor element such as a semiconductor sensor may be used as the temperature sensor.

[0006]

As described above, according to the first aspect of the present invention, since the vibrator is directly heated by a surface-mount type heater without using a constant temperature bath made of metal or the like, the size and the size are low. The effect that cost reduction can be performed easily is produced. In addition, a small heater is attached to the lead terminal to heat the crystal plate without using a metal block so that the heat is directly transmitted to the crystal element plate. This reduces the heating volume and reduces the current consumption of the oscillator. At the same time, there is also an effect that the rise time from when the power is turned on until the frequency is stabilized is short. According to a second aspect of the present invention, in addition to the effects of the first aspect of the present invention, the quartz oscillator is directly heated in a well-balanced manner by an individual heater, and further, the screw of the piezoelectric element plate is directly transmitted. Since the heater is also attached to the lead terminal portion and heated, there is an effect that an oscillator having excellent start-up characteristics in which the oscillation frequency is stabilized in a short time with respect to a temperature change can be formed.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a crystal oscillator according to the present invention.

FIG. 2 is a diagram showing one embodiment of a temperature control circuit used in the present invention.

FIG. 3 is a diagram showing a conventional crystal oscillator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Printed circuit board, 2 ... Oscillation circuit, 3 ... Temperature control circuit, 4, 4 ', 5', 6, 6 '... Surface mount type small heater, 7 ... Temperature Sensor, 8: metal piece, 9: metal cap, 10: crystal oscillator, 1
1, 11 ': lead terminal, 12: power transistor, 100: metal block, 101: crystal oscillator, 102: substrate, 103: heater wire, 1
04: semiconductor element, 105: temperature sensor, 10
6 ... substrate, 107 ... metal container, 108 ... heat insulating material

Claims (2)

[Claims] A piezoelectric vibrator, an oscillating circuit, a plurality of surface-mounted heaters, and a temperature control circuit for controlling a heating temperature of the heater are disposed on a substrate. A piezoelectric oscillator wherein the case of the piezoelectric vibrator and the lead terminal of the piezoelectric vibrator are simultaneously heated by separate heaters so as to simultaneously heat the circuit and the temperature control circuit. 2. The piezoelectric oscillator according to claim 1, wherein a ratio of power supplied to each heater is set so that an oscillation frequency of the oscillator is stabilized according to a difference in heat capacity of the piezoelectric vibrator.