JP2748740B2 - Temperature compensated oscillator and temperature detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature compensated oscillator having a crystal oscillator as a temperature sensor and a temperature detecting device.

[0002]

2. Description of the Related Art A temperature-compensated oscillator includes a voltage-controlled oscillator (VCO) as a main oscillator, a temperature detecting device for detecting a peripheral temperature of the main oscillator, and a VCO according to a result of the temperature detection.
And a control voltage supply means for generating a control voltage for compensating for a temperature change of the oscillation frequency and maintaining the same at a constant value and applying the control voltage to the VCO. The temperature detecting device has an oscillator having a crystal oscillator for temperature detection, and the detected temperature is represented by the frequency of an electric signal output from the oscillator.

Conventionally, as a piezoelectric oscillator for detecting temperature,
Proceedings of the 43rd Annual Symposium on Frequency Control (Proceedings of the 43
rd Annual Symposium on Fr
equipment, 1989, 51-
As described in the article on page 54, a combination of an AT-cut crystal resonator having a small temperature coefficient of the natural frequency and a Y-cut crystal resonator having a large temperature coefficient of the natural frequency is used. Have been done. In this case, the temperature detector
The output pulse of the oscillator by the AT cut crystal oscillator is
While counting the rising period of the output pulse of the oscillator by the Y-cut crystal oscillator, and repeating the operation of resetting the count result to zero at every preset cycle, the count result immediately before the reset is transmitted as a detected temperature signal.

[0004] Instead of performing temperature detection with a combination of two crystal oscillators, a circuit that uses a single crystal oscillator is based on the Procedures of the Forty-Force Annual.
Symposium on Frequency Control (P
rosedings of the 44th Ann
ual Symposium on Frequency
Control), 1990, pp. 597-614. This circuit has one SC-cut crystal resonator for temperature detection, and this crystal resonator is excited by two oscillation circuits for a fundamental wave and a harmonic, thereby oscillating both a fundamental wave and a third harmonic. An output is generated, and a signal representing a frequency difference between the two is used as a detected temperature signal.

[0005]

The former of the above two prior art crystal oscillators, that is, the combination of two crystal oscillators of AT-cut and Y-cut, is used for turning on the power or suddenly changing the ambient temperature. In the case where a rapid temperature change occurs, there is a problem that a temperature detection error transiently increases. That is, to increase the temperature detection accuracy is set considerably increase the ratio of the resonance frequency (f _Y) towards the resonant frequency (f _A) and Y-cut towards the AT-cut (e.g., f
_{A = 1MHz, f Y = 10KHz} ) of it is normally
As a result, the volume and heat capacity of the Y-cut crystal resonator are considerably larger than those of the AT-cut crystal resonator. Therefore, when a large difference occurs between the thermal time constants of the two and a rapid temperature change occurs, avoid a temperature detection error due to the temperature difference between the two during a transitional period until reaching a steady temperature state. I can't get it. On the other hand, in the latter case of the above-described prior art, that is, in a configuration in which a fundamental wave and a third harmonic are generated by one SC-cut crystal resonator,
Although there is no problem of the temperature detection error caused by the difference of the thermal time constants, the problem of increasing the power consumption of the oscillation circuit for generating the third harmonic is unavoidable. That is, since the power consumption of the semiconductor device constituting the oscillator circuit increases almost in proportion to the oscillation frequency, the power consumption of the oscillator circuit for the third harmonic is almost three times as large as that for the fundamental wave. ,
When they are added together, the power consumption reaches almost four times that of the fundamental wave.

Accordingly, an object of the present invention is to provide a temperature-compensated oscillator and a temperature detection device which do not involve the occurrence of a temperature detection error due to the difference between the thermal time constants and do not require a large increase in the power consumption of the oscillation circuit. It is to be.

[0007]

According to the present invention, there is provided a temperature compensated oscillator for changing an oscillation frequency in response to a control voltage, and a temperature for generating an electric signal representing a temperature change around the voltage controlled oscillator. A temperature compensation oscillator comprising: a detection unit; and a control voltage supply unit configured to apply, to the voltage control oscillator, an analog voltage that cancels an influence of the temperature change on the voltage control oscillator as the control voltage in response to the electric signal. Wherein the temperature detecting means is formed in a pair of AT-cut quartz oscillators having substantially equal natural frequencies and mutually different cut angles, and in a film shape on both surfaces of each of these quartz oscillators. Electrodes, a plurality of support members for holding the crystal unit at these electrode portions, respectively, and accommodating the crystal unit while holding these support members Case members, first and second oscillators each having the quartz resonator connected to a resonance circuit, and an electric signal indicating a difference between the oscillating frequencies of the oscillators, thereby generating a frequency difference signal indicating the temperature change. And a circuit.

A temperature detecting device according to the present invention comprises a first and a second quartz oscillators whose natural frequency changes with respect to temperature are different from each other, and a first and a second oscillator respectively connecting these quartz oscillators to a resonance circuit. And a means for generating an electric signal representing a temperature change in the vicinity of the quartz oscillator in response to the oscillation frequency of these oscillators,
The first and second quartz resonators have a pair of A's having substantially equal natural frequencies and mutually different cut angles.
It is a T-cut quartz resonator element, and the electric signal generating means has a reversible counter for counting up and down the output pulses of the first and second oscillators, respectively.

[0009]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. In the figure, crystal oscillators Q1 and Q2,
Oscillators 51 and 52 each including these in a resonance circuit
And a counter 53 for counting up and down the number of oscillation output pulses of the oscillators 51 and 52, respectively, to generate a signal representing a temperature change near the crystal units Q1 and Q2. It is sent to a read only memory (ROM) 54. Quartz resonator Q
1 and Q2 are AT cut plates having cut angles of 35 ° 25 ′ and 35 ° 17 ′, respectively, and have substantially equal natural frequencies. Crystal oscillators Q1 and Q2 are connected to oscillator 5
1 and 52, respectively, and the frequencies f1 and f
2 is generated. The counter 53 is a reversible counter that counts up one pulse of both output signals of the oscillators 51 and 52 and counts down the other pulse, and repeats an operation of resetting the count result to zero at a preset cycle. Meanwhile, a digital signal indicating the counting result immediately before the reset is sent to the read-only memory (ROM) 54 as a read address signal.
For the reset timing instruction, one of the divided pulses of the output signals of the oscillators 51 and 52 is used.

FIG. 2 shows the above-described quartz oscillators Q1 and Q2.
FIG. 3 is a characteristic diagram showing an example of a temperature characteristic of the resonance frequency of FIG. 1 with the horizontal axis representing temperature and the vertical axis representing relative frequency, which is the rate of change (Δf / f) of the resonance frequency. The quartz oscillators Q1 (AT cut with a cut angle of 35 ° 25 ') and Q2 (cut angle of 3
Curves AT1 and AT2 show the change of the resonance frequency (5 ° 17 ′ AT cut) with the temperature change. As is clear from these characteristic curves AT1 and AT2, the display value of the digital signal output from the counter 53,
That is, the value obtained by multiplying the difference between the frequencies f1 and f2 by the reset cycle increases (or decreases) monotonically as the temperature rises. Therefore, the detected temperature can be uniquely displayed by the read address signal given from the counter 53 to the ROM 54.

A digital value of a control voltage to be applied in order to keep the oscillation frequency f0 of the voltage controlled oscillator (VCO) 56 as a main oscillator constant at a temperature corresponding to the read address signal is written in the ROM 54 in advance. Leave. The digital control voltage read from the ROM 54 in response to the read address signal given from the counter 53 is converted into an analog voltage by a digital-to-analog converter (DAC) 55, and then applied to the VCO 56 as a control voltage. Control is performed to keep the oscillation frequency f0 constant.

FIGS. 3 (a), 3 (b) and 3 (c) are a side sectional view and a perspective view, respectively, showing one structural example of the quartz oscillators Q1 and Q2 in this embodiment. A vibrator element 1 corresponding to a plate-shaped AT-cut quartz crystal vibrator Q1 and Q2 having substantially equal natural frequencies and different cut angles.
, 2, holding means, described later, for holding the transducer pieces 1, 2, with their plate surfaces parallel and facing each other and holding them vertically, and a metal case 8 for accommodating these elements. Electrodes 3, 4 for electrical connection are provided on both sides of each of vibrator pieces 1 and 2.
And 5, 6 were formed by gold deposition, respectively. The lower ends of the vibrator pieces 1 and 2 are sandwiched by the upper side of a holding member 7 made of a T-shaped conductive material having a lower end fixed to the inner bottom surface of the metal case 8. The electrode 5 of the vibrator element 2 is electrically connected to the upper side of the holding member 7. Electrode 3 of vibrator element 1 and electrode 6 of vibrator element 2
Are terminals 9 and 1 made of a rod-shaped conductive material penetrated and fixed to the bottom surface of the metal case 8 via insulating members 11 and 12.
0, and are electrically connected to each other.

To connect to a temperature detecting oscillator, the terminals 9 and 10 are connected by wiring with the bottom surface of the metal case 8 placed on a wiring board (not shown). Since the vibrator pieces 1 and 2 are opposed to each other and held vertically, the bottom area of the metal case 8, that is, the area occupied by mounting on the wiring board can be reduced.

FIG. 4 is a side sectional view showing another example of the structure of the crystal units Q1 and Q2 of the above embodiment. Vibrator pieces 1 and 2 made of plate-shaped AT-cut quartz having natural frequencies substantially equal to each other and having different cut angles, and the plate surfaces of these vibrator pieces 1 and 2 are aligned on the same plane and horizontally adjacent to each other. A holding means to be described later and a metal case 18 for housing these elements are provided. Transducer pieces 1 and 2
Are sandwiched and electrically connected at the upper end of a holding member 17 made of a rod-shaped conductive material having a lower end fixed to the inner bottom surface of the metal case 18. An end is a terminal 19 made of a rod-shaped conductor material which is fixed to the side surface of the metal case 18 through insulating members 21 and 22.
And 20 at the ends thereof and are electrically connected. When mounting this crystal unit on a printed wiring board and assembling it into a package, the bottom surface of the case 18 is mounted on a wiring board, and the outer ends of the terminals 19 and 20 are bent downward for wiring connection. Since the vibrator pieces 1 and 2 are horizontally held on the same plane, the height on the wiring board can be reduced, which is suitable for so-called planar mounting.

In each of the above-described configuration examples of the crystal units Q1 and Q2, the vibrator pieces 1 and 2 have substantially the same fixed frequency, and therefore have substantially the same external dimensions and substantially the same thermal time constant. Can be aligned. Further, since both are housed close to each other in the same case, the temperature of both during use is always kept uniform. Therefore, AT
A temperature detection error does not occur due to a difference in thermal time constant as in a conventional oscillator in which two crystal oscillators of a cut and a Y-cut are combined.

The oscillation circuits 51 and 52 that oscillate by connecting the vibrator pieces 1 and 2 operate with fundamental waves having substantially the same frequency.
There is no need to increase power consumption associated with harmonic oscillation as in the conventional case using a C-cut crystal resonator.

In the configuration examples shown in FIGS. 3A and 4, the vibrator pieces 1 and 2 each have an electrode 4 on one side.
Although the electrodes 5 and 5 are commonly connected, these electrodes may be separated and individually led to the outside and connected. As illustrated in FIG. 1, the crystal units Q1 and Q2
When the oscillator and the oscillator 51 or 52 are used with a common ground connection, if the common connection is made in the metal case as in each of the above-described configuration examples, the wiring on the wiring board can be prevented from becoming complicated.

[0019]

As described above, according to the present invention, a pair of A's having substantially equal oscillation frequencies and different cut angles are provided.
By using a T-cut quartz resonator as a temperature sensor, it is possible to avoid occurrence of a temperature detection error due to a difference in thermal time constant, and to avoid a large increase in power consumption of an oscillator for temperature detection.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a temperature characteristic diagram of a quartz oscillator pair used in an embodiment of the present invention.

FIG. 3A is a side sectional view of a configuration example of a crystal resonator according to an embodiment of the present invention, and FIGS. 3B and 3C are perspective views of components of the crystal resonator.

FIG. 4 is a side sectional view of a configuration example of a crystal resonator according to an embodiment of the present invention.

[Explanation of symbols]

 1, 2 vibrator piece 3 to 6 electrode 7, 17 holding material 8, 18 metal case 9, 10, 19, 20 terminal 11, 12, 21, 22 insulating member 51, 52 oscillator 53 counter 54 read-only memory (ROM) 55 Digital-to-analog converter (DAC) 56 Voltage-controlled oscillator (VCO) Q1, Q2 Quartz resonator

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-196634 (JP, A) JP-A-62-239707 (JP, A) JP-A-63-152223 (JP, A) JP-A-2- 57928 (JP, A) JP-A-55-138626 (JP, A) JP-A-59-95431 (JP, A) JP-A-48-52255 (JP, A) Real opening 60-184320 (JP, U) (58) Field surveyed (Int.Cl. ⁶ , DB name) H03L 1/02 H03H 9/205 G01K 7/32

Claims (3)

(57) [Claims] A voltage-controlled oscillator for changing an oscillation frequency in response to a control voltage; a temperature detecting means for generating an electric signal indicating a temperature change around the voltage-controlled oscillator; A temperature-compensated oscillator comprising: a control voltage supply unit configured to apply an analog voltage that cancels out the effect of the temperature change on the voltage-controlled oscillator as the control voltage to the voltage-controlled oscillator. A pair of AT-cut quartz oscillators having a frequency and a cut angle different from each other, electrodes formed in a film shape on both surfaces of each of the quartz oscillators, and the quartz oscillator at these electrode portions. A plurality of support members for respectively holding the crystal elements, a case member for holding the crystal members and holding the support members, and a resonance circuit First and second connected respectively to
And a frequency difference signal generating circuit for generating an electric signal indicating a difference between the oscillating frequencies of the oscillators and thereby indicating the temperature change. 2. The frequency difference signal generating circuit according to claim 1, wherein
And a reversible counter for counting up and counting down the number of output pulses of the second oscillator, respectively.
And the control voltage supply means stores in advance a plurality of digital values which the control voltage can take at a plurality of addresses, respectively, selects one of the plurality of addresses in response to an output of the reversible counter, and selects the address. 2. The temperature-compensated oscillator according to claim 1, further comprising: a read-only memory for reading the digital value stored in the memory; and a conversion unit for converting the digital value to the analog voltage. 3. A first and second crystal oscillators whose natural frequency changes in temperature with respect to each other are different from each other; a first and a second oscillator each having the crystal oscillator connected to a resonance circuit;
Means for generating an electric signal indicating a temperature change in the vicinity of the crystal unit in response to the oscillation frequency of the oscillator, wherein the first and second crystal units are substantially equal to each other. A pair of AT-cut quartz-crystal vibrating pieces having a frequency and a cut angle different from each other, and wherein the electric signal generating means counts up and counts down output pulses of the first and second oscillators, respectively. A temperature detecting device having a reversible counter.