JP2008092111A - Inspection method for temperature compensation piezoelectric oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection method for a temperature compensation piezoelectric oscillator capable of checking whether a temperature compensation operation functions normally or not, without using a thermostatic oven. <P>SOLUTION: The inspection method for a temperature compensation piezoelectric oscillator comprises: a process A for preparing a reference temperature compensation piezoelectric oscillator, and acquiring an output frequency value when a supply voltage value for outputting to a pseudo temperature information signal is impressed onto its temperature sensor element; a process B for preparing a temperature compensation piezoelectric oscillator to be inspected, and acquiring an output frequency value when a supply voltage value of the same value as the supply voltage value in Process A is impressed onto its temperature sensor element; a process C for comparing the output frequency value acquired at the process A with the one at the process B, and classifying accepted products and rejected products for the temperature compensation piezoelectric oscillators, wherein difference between both of the output frequency values is below an error for the accepted products, but the difference is equal to or above the error for the rejected products; and a process for sending the accepted products to the next process, but for writing a compensation data in a memory element again for the rejected products and repeating from the process B to the process C. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a temperature-compensated piezoelectric oscillator inspection method capable of making the output signal frequency substantially constant within a certain temperature range, and more particularly to a temperature-compensated operation inspection method in a temperature-compensated piezoelectric oscillator.

  Conventionally, a piezoelectric oscillator composed of a piezoelectric vibrator and an integrated circuit element incorporating various electronic circuits for controlling the operation of the piezoelectric vibrator has been used as a reference for operating frequency or time in electronic equipment. Yes. In particular, in recent years, the demand for piezoelectric oscillators for mobile communications including mobile phones has been increasing. In recent electronic devices, high stability and high accuracy are desired. For example, the oscillation frequency of a piezoelectric oscillator using a piezoelectric vibrator is also highly stable against changes in the usage environment. In particular, the oscillation frequency is required to be stable with respect to temperature changes. As a countermeasure, a nonlinear function is generated for the temperature detected by the temperature sensor element, and this function is used as a control signal to adjust the capacitance of the variable capacitance element connected in series to the piezoelectric vibrator. A temperature-compensated piezoelectric oscillator that compensates for the oscillation frequency of the piezoelectric vibrator that changes due to the above is used. In general, the temperature characteristics of the oscillation frequency of a piezoelectric vibrator using a crystal formed by AT cut as a piezoelectric material can be approximated by a cubic function, and compensation data for compensating the temperature characteristic is also a cubic function. Given.

  A circuit that generates such a cubic function can be easily realized by a semiconductor integrated circuit or the like. For variations in the temperature characteristics of piezoelectric oscillators and piezoelectric vibrators, the coefficients and constants of each order of compensation data for temperature compensation are stored in a memory element, and the value stored in this memory element is changed. It corresponds with.

  The configuration of a conventional temperature compensated piezoelectric oscillator includes an oscillation circuit and a piezoelectric vibrator connected to the input of the oscillation circuit, and these constitute a piezoelectric oscillation circuit unit. At the input end of the piezoelectric oscillation circuit unit, a variable capacitance element is provided in series with the piezoelectric vibrator to adjust the oscillation frequency of the piezoelectric oscillation circuit unit by changing the capacitance by applying a control voltage. For example, a variable capacitance diode is used as the variable capacitance element. This temperature-compensated piezoelectric oscillator further includes a control voltage according to the ambient temperature applied to the variable capacitance element to compensate for fluctuations in the oscillation frequency of the oscillation circuit due to temperature changes. A temperature compensation circuit unit composed of a quadratic function generation circuit and a memory element is connected, and a temperature sensor element is connected to the cubic function generation circuit.

  The cubic function generation circuit generates a cubic function corresponding to the coefficient and constant of each order term of the cubic function given from the memory element connected to the ambient temperature detected by the connected temperature sensor element. Generated and provided as a control signal to the variable capacitance element described above.

The temperature compensated piezoelectric oscillator as described above is disclosed in the following prior art documents.
JP 2005-347929 A Japanese Patent No. 3310550 Japanese Patent Laid-Open No. 2003-163541 JP-A-3-280703

  In addition, the applicant has not found any prior art documents related to the present invention by the time of filing of the present application other than the prior art documents specified by the above prior art document information.

  In the temperature-compensated piezoelectric oscillator as described above, as a method for inspecting whether the temperature characteristic of the oscillation frequency of the piezoelectric vibrator is normally compensated by the compensation data in the memory element, conventionally, a plurality of temperatures to be inspected are used. Prepare a compensated piezoelectric oscillator, and place the temperature compensated piezoelectric oscillator in a thermostatic chamber that can change the temperature in the tank within a certain range, and vary the temperature in the tank within the specified temperature range. While the temperature compensated piezoelectric oscillator is actually operated, the output signal frequency at that time is measured, and a method of inspecting whether the temperature compensation operation is functioning normally is used, but in this inspection method, It takes a very long time to change the temperature in the thermostatic chamber to a plurality of predetermined temperatures, and to maintain the temperature in the bath at the predetermined temperature for a certain period of time. It is causing the time of. In particular, when a large-sized thermostatic chamber is used to inspect many temperature-compensated piezoelectric oscillators at the same time, it takes more time to maintain the temperature because the space in the chamber becomes wider, and the lengthening of the process becomes remarkable. There is a risk that.

  Therefore, an object of the present invention is to provide an inspection method for a temperature-compensated piezoelectric oscillator that can confirm whether or not the temperature-compensated operation is functioning normally without using a thermostat.

The inspection method for a temperature-compensated piezoelectric oscillator according to the present invention compensates for at least an oscillation circuit incorporating a piezoelectric vibrator, a temperature sensor element installed in the vicinity of the piezoelectric vibrator, and temperature characteristics of the oscillation frequency of the piezoelectric vibrator. Therefore, a memory element in which compensation data based on coefficients and constants of each order of the function is written, and a detected temperature signal from the temperature sensor element are input, and the oscillation frequency of the piezoelectric vibrator is determined according to the detected temperature signal. A temperature-compensated piezoelectric oscillator comprising a cubic function generating circuit that generates a nonlinear function signal for compensating temperature characteristics based on each data written in the memory element and outputs the nonlinear function signal to an oscillation circuit. In the temperature compensation operation inspection method,
A reference temperature compensation type piezoelectric oscillator in which correct compensation data is input in a memory element is prepared, and the temperature sensor element provided in the reference temperature compensation type piezoelectric oscillator is input from this temperature sensor element to a cubic function generation circuit. Step A for obtaining the frequency value of the compensated output signal of the oscillation circuit when a power supply voltage value for pseudo-outputting a signal having the same value as when the detected temperature signal is detected at an arbitrary temperature is applied When,
Prepare at least one temperature compensated piezoelectric oscillator to be inspected, and generate a cubic function from the temperature sensor element of the reference temperature compensated piezoelectric oscillator in step A to the temperature sensor element provided in the temperature compensated piezoelectric oscillator to be inspected Output signal frequency of the oscillation circuit when a power supply voltage value that is the same as the power supply voltage value applied to output a signal with the same value as the detected temperature signal input to the circuit is detected. Step B for obtaining a value;
The frequency value of the output signal of the reference temperature compensated piezoelectric oscillator obtained in step A is compared with the frequency value of the output signal of the temperature compensated piezoelectric oscillator obtained in step B, and the difference between the two frequency values is an error. A process C for classifying the temperature compensated piezoelectric oscillator to be inspected below and the temperature compensated piezoelectric oscillator to be inspected whose difference between both frequency values is equal to or greater than an error;
The temperature-compensated piezoelectric oscillator to be inspected whose difference is less than the error is sent to the next step, and the temperature-compensated piezoelectric oscillator to be inspected whose difference is greater than or equal to the error writes compensation data to the memory element again. And a step of repeating step B and subsequent steps.

  Further, according to the inspection method of the temperature compensated piezoelectric oscillator of the present invention, the assumed detection temperature of the power supply voltage value applied to the temperature sensor element in the reference temperature compensated piezoelectric oscillator and the temperature compensated piezoelectric oscillator to be inspected is 0 ° C. It is characterized by.

  According to the inspection method of the temperature compensated piezoelectric oscillator of the present invention, it is possible to check whether the temperature compensated operation of the temperature compensated piezoelectric oscillator is functioning normally without using an inspection method using a thermostat. By changing the detected voltage of the temperature sensor element by changing the power supply voltage applied to the element, it is possible to confirm the temperature compensation operation of the temperature compensated piezoelectric oscillator to be inspected.

  Therefore, according to the present invention, it is possible to provide an inspection method capable of confirming the temperature compensation operation of the temperature compensated piezoelectric oscillator simply and in a short time.

Hereinafter, an embodiment of an inspection method for a temperature compensated piezoelectric oscillator according to the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of a temperature compensated piezoelectric oscillator according to the present invention. FIG. 2 is a process flow chart showing a temperature-compensated piezoelectric oscillator inspection method according to the present invention. FIG. 3 is a graph showing characteristics between the detected temperature and the power supply voltage value in the temperature sensor element 5 shown in FIG. In each figure, a part of the block and the flowchart are not shown for clarity of explanation.

  The configuration of the temperature compensated piezoelectric oscillator 100 according to the present invention includes an oscillation circuit 101 and a piezoelectric vibrator 102 connected to an input of the oscillation circuit 101, and these constitute a piezoelectric oscillation circuit unit. At the input of the piezoelectric oscillation circuit unit, a variable capacitance element 103 is provided in series with the piezoelectric vibrator 102 to change the capacitance by applying a control voltage and adjust the oscillation frequency of the piezoelectric oscillation circuit unit. As this variable capacitance element 103, for example, a variable capacitance diode or the like is used. In addition, the temperature compensated piezoelectric oscillator 100 further applies a control voltage corresponding to the ambient temperature to the variable capacitance element 103 to compensate for fluctuations in the oscillation frequency of the oscillation circuit 101 due to temperature changes, so that the cubic function generation circuit 104 is used. The temperature compensation circuit unit 107 is provided by the memory element 106, and the temperature sensor element 105 provided in the vicinity of the piezoelectric vibrator 102 is connected to the cubic function generation circuit 104.

  The cubic function generation circuit 104 is configured according to the coefficients and constants of the terms of each degree of the cubic function given from the memory element 106 with respect to the temperature information signal in the vicinity of the piezoelectric vibrator 102 detected by the temperature sensor element 105. A next function is generated and given to the variable capacitance element 103 as a control signal.

  Here, the characteristic part of the present invention is to confirm whether or not the temperature compensation operation is functioning normally. By changing the power supply voltage value (Vcc) applied to the temperature sensor element 105, the temperature from the temperature sensor element 105 is simulated. An information signal is transmitted, and it is to confirm whether the temperature compensation operation of the temperature compensated piezoelectric oscillator is functioning normally based on the signal.

  A specific method for inspecting a temperature compensation operation in a temperature compensated piezoelectric oscillator is a reference temperature compensation type in which correct compensation data is input into the memory element 106 as step A as shown in the process flowchart of FIG. A piezoelectric oscillator is prepared, and when a detected temperature signal input from the temperature sensor element 105 to the cubic function generating circuit 4 detects an arbitrary temperature on the temperature sensor element 105 provided in the reference temperature compensation type piezoelectric oscillator. The frequency value of the compensated output signal of the oscillation circuit 101 when the power supply voltage value (Vcc) for pseudo-outputting the same value signal is applied is acquired.

  Next, as step B, at least one temperature compensated piezoelectric oscillator to be inspected is prepared, and the temperature sensor element 105 provided in the temperature compensated piezoelectric oscillator to be inspected is connected to the reference temperature compensated piezoelectric oscillator in step A described above. A power supply having the same value as the power supply voltage value (Vcc) applied to output a signal having the same value as when the detected temperature signal input from the temperature sensor element 5 to the cubic function generating circuit 104 detects an arbitrary temperature. The output signal frequency value of the oscillation circuit 101 when the voltage value (Vcc) is applied is acquired.

  Next, as step C, the frequency value of the output signal of the reference temperature compensated piezoelectric oscillator acquired in step A above and the frequency value of the output signal of the temperature compensated piezoelectric oscillator acquired in step B described above are obtained. In comparison, the temperature-compensated piezoelectric oscillator to be inspected whose difference between both frequency values is less than the error and the temperature-compensated piezoelectric oscillator to be inspected in which the difference between both frequency values is equal to or greater than the error are classified.

  After that, in the above-mentioned process C, the temperature compensated piezoelectric oscillator to be inspected whose difference between the frequency values is less than the error is sent to the next process as an acceptable product, and the temperature compensated inspected type in which the difference is equal to or greater than the error The piezoelectric oscillator again writes the compensation data to the memory element 106 and then repeats the process B and subsequent steps.

  For example, the flow of the inspection process will be described using an example in which an arbitrary temperature is 0 ° C. First, a power supply voltage value for artificially outputting a signal having the same value as when a detected temperature signal is detected at a temperature of 0 ° C. to a reference temperature compensated piezoelectric oscillator in which correct compensation data is input in the memory element 106 The frequency value (f0) of the compensated output signal of the oscillation circuit 101 when (Vcc) is applied is measured (step A).

Next, at least one temperature compensated piezoelectric oscillator to be inspected is prepared, and the temperature sensor element 105 provided in the temperature compensated piezoelectric oscillator to be inspected is transferred from the temperature sensor element 105 of the reference temperature compensated piezoelectric oscillator in step A. A power supply voltage value equal to the power supply voltage value (Vcc) applied to output a signal having the same value as when the detected temperature signal input to the cubic function generation circuit 104 detects a temperature of 0 ° C. (FIG. 3). The output signal frequency value (f1) of the oscillation circuit 101 when V1) is applied is measured (step B), and finally the frequency value (f0) of the output signal of the reference temperature compensated piezoelectric oscillator measured in step A is measured. Is compared with the frequency value (f1) of the output signal of the temperature compensated piezoelectric oscillator to be inspected measured in the process B, and the temperature compensated piezoelectric oscillator to be inspected whose difference between both frequency values is less than an error, and both frequency values while The temperature compensated piezoelectric oscillator with the difference greater than the error is classified and the temperature compensated piezoelectric oscillator with the difference less than the error is sent to the next process, and the difference is greater than the error. The temperature-compensated piezoelectric oscillator to be inspected repeats the process B and subsequent steps after writing compensation data into the memory element 106 again.

  According to the inspection method of the temperature compensated piezoelectric oscillator in the present invention described above, the power supply applied to the temperature sensor element can be confirmed without using the inspection method using a thermostatic bath to confirm whether the temperature compensation operation is functioning normally. By changing the voltage value (Vcc), a temperature information signal from the temperature sensor element is artificially transmitted, and whether or not the temperature compensation operation of the temperature compensated piezoelectric oscillator operates normally based on the pseudo temperature information signal Can be confirmed.

  Therefore, the temperature-compensated piezoelectric oscillator is placed in a thermostatic chamber that can change the temperature in the tank within a certain range, and the temperature-compensated piezoelectric oscillator is actually operated while varying the temperature in the tank within a predetermined temperature range. In the conventional method of operating, measuring the output signal frequency at that time, and checking whether the temperature compensation operation is functioning normally, it takes a very long time to keep the inside of the tank at the predetermined temperature for a certain period of time. However, the temperature compensated piezoelectric oscillator manufacturing process including the inspection process has led to a long time, but the temperature compensated piezoelectric oscillator inspection method of the present invention confirms the temperature compensated operation without using a thermostat. Therefore, various problems caused by using the thermostatic bath can be solved, and the manufacturing process of the temperature compensated piezoelectric oscillator can be shortened.

FIG. 1 is a block diagram showing a schematic configuration of a temperature compensated piezoelectric oscillator according to the present invention. FIG. 2 is a process flow chart showing a temperature-compensated piezoelectric oscillator inspection method according to the present invention. FIG. 3 is a graph showing characteristics between the detected temperature and the power supply voltage value in the temperature sensor element shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Temperature compensation type | mold piezoelectric oscillator 101 ... Oscillation circuit 102 ... Piezoelectric vibrator 103 ... Variable capacity element 104 ... Tertiary function generation circuit 105 ... Temperature sensor element 106 ... Memory Element 107 ... Temperature compensation circuit Vcc ... Power supply voltage value

Claims (2)

at least,
An oscillation circuit incorporating a piezoelectric vibrator;
A temperature sensor element installed in the vicinity of the piezoelectric vibrator;
A memory element in which compensation data by coefficients and constants of each order of the function for compensating the temperature characteristics of the oscillation frequency of the piezoelectric vibrator is written;
A detection temperature signal from the temperature sensor element is input, and a nonlinear function signal that compensates for a temperature characteristic of the oscillation frequency of the piezoelectric vibrator according to the detection temperature signal is based on each data written in the memory element. In a method for inspecting a temperature compensation operation in a temperature compensated piezoelectric oscillator configured by a cubic function generation circuit that generates and outputs the nonlinear function signal to the oscillation circuit,
A reference temperature compensation type piezoelectric oscillator in which correct compensation data is input in the memory element is prepared, and the temperature sensor element provided in the reference temperature compensation type piezoelectric oscillator is transferred from the temperature sensor element to the cubic function. The frequency value of the compensated output signal of the oscillation circuit when applying a power supply voltage value for pseudo-outputting a signal having the same value as when the detection temperature signal input to the generation circuit detects an arbitrary temperature Step A for obtaining
At least one temperature compensated piezoelectric oscillator to be inspected is prepared, and the temperature sensor element provided in the temperature compensated piezoelectric oscillator to be inspected is moved from the temperature sensor element of the reference temperature compensated piezoelectric oscillator in the step A to the temperature sensor element. The detection temperature signal input to the cubic function generation circuit is applied with a power supply voltage value that is the same as the power supply voltage value applied to output a signal having the same value as that detected when an arbitrary temperature is detected. Step B for obtaining an output signal frequency value of the oscillation circuit;
The frequency value of the output signal of the reference temperature compensated piezoelectric oscillator acquired in the step A is compared with the frequency value of the output signal of the temperature compensated piezoelectric oscillator to be inspected acquired in the step B. Classifying the inspected temperature compensated piezoelectric oscillator whose difference is less than an error and the inspected temperature compensated piezoelectric oscillator in which the difference between both frequency values is equal to or greater than the error;
The temperature compensated piezoelectric oscillator to be inspected whose difference is less than an error is sent to the next step, and the temperature compensated piezoelectric oscillator to be inspected whose difference is equal to or more than an error is again supplied to the memory element as the compensation. A method for inspecting a temperature-compensated piezoelectric oscillator, comprising the steps of repeating the process B and subsequent steps after writing data.   2. The temperature compensation type according to claim 1, wherein an assumed detection temperature of a power supply voltage value applied to the temperature sensor element is 0 ° C. in the reference temperature compensation type piezoelectric oscillator and the temperature compensation type piezoelectric oscillator to be inspected. Inspection method of piezoelectric oscillator.

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