Quartz-temperature-measurement probe and quartz-temperature-measurement device

• US 9,228,906 B2
• Filed: 09/02/2013
• Issued: 01/05/2016
• Est. Priority Date: 09/21/2012
• Status: Active Grant

• Current Assignee: Masato Tanabe
• Original Assignee: Masato Tanabe
• Inventors: Tanabe, Masato
• Primary Examiner(s): KAPLAN VERBITSKY, GAIL
• Application Number:
  US14/376,780
• Publication Number:
  US 20150023388A1
• Time in Patent Office: 855 Days
• Field of Search: 374/100, 374117-119, 374/172, 374/184, 374/1, 331/66, 331/117.R, 331/167, 331/54, 331/175, 331/176, 331/158, 331/177.R, 331/23, 702/130, 702/99
• US Class Current: 1/1
• CPC Class Codes: G01K 7/32 using change of resonant frequency of a crystal

Abstract

A crystal oscillator (31) (Y-cut) has a temperature characteristic in which its oscillating frequency significantly changes with temperature, whereas a crystal oscillator (32) (AT-cut) has a temperature characteristic in which its oscillating frequency is stable with temperature. Crystal oscillators (31, 32) are cut from a raw material of the same type and configured to be substantially equal in shape, material, and size, and provide a combination of oscillation frequencies such that the frequency of a signal generated by a differential frequency circuit (35) will be less than or equal to 10 kHz within a measuring temperature range of 21 to 30° C. The frequency of a signal generated by differential frequency generating circuit (35) is output to a measurement apparatus main unit and a frequency counting circuit (15) measures the frequency of this signal by a reciprocal counting method to obtain at least eight or more significant digits.

Claims

1. A quartz temperature measuring probe comprising:

a first crystal oscillator of AT-cut orientation having a temperature characteristic in which its oscillating frequency is stable with temperature;

a second crystal oscillator of Y-cut or LC-cut orientation having a temperature characteristic in which its oscillating frequency significantly changes with temperature as compared with the first crystal oscillator;

a first oscillation circuit that generates a signal of a specific oscillating frequency, using the first crystal oscillator as an oscillation element;

a second oscillation circuit that generates a signal of a specific oscillating frequency, using the second crystal oscillator as an oscillation element; and

a differential frequency generating circuit that generates a signal of a differential frequency component between an oscillating frequency from the first oscillation circuit and an oscillating frequency from the second oscillation circuit,

wherein the frequency of the second crystal oscillator changes by about 1000 Hz with a temperature change of 1°

C.;

the first crystal oscillator and the second crystal oscillator are held to have the same positional relation to a location where temperature should be measured and cut from a raw material of the same type and configured to be substantially equal in shape and material, and provide a combination of oscillation frequencies such that the frequency of a signal which is generated by the differential frequency generating circuit will be less than or equal to 10 kHz within a preset measuring temperature range; and

said quartz temperature measuring probe measuring a temperature of a target medium with a precision on the order of one millionth of 1°

C. within a preset measuring temperature range.

2. A quartz temperature measurement device comprising:

a quartz temperature measuring probe including a first crystal oscillator of AT-cut orientation having a temperature characteristic in which its oscillating frequency is stable with temperature, a second crystal oscillator of Y-cut or LC-cut orientation having a temperature characteristic in which its oscillating frequency significantly changes with temperature as compared with the first crystal oscillator, a first oscillation circuit that generates a signal of a specific oscillating frequency, using the first crystal oscillator as an oscillation element, a second oscillation circuit that generates a signal of a specific oscillating frequency, using the second crystal oscillator as an oscillation element, and a differential frequency generating circuit that generates a signal of a differential frequency component between an oscillating frequency from the first oscillation circuit and an oscillating frequency from the second oscillation circuit; and

a measurement apparatus main unit including a frequency counter that measures the frequency of a signal received from the quartz temperature measuring probe, conversion means that converts a frequency measured by the frequency counter to a measurement temperature, and a display unit that displays a measurement temperature obtained by the conversion means,

wherein the frequency of the second crystal oscillator changes by about 1000 Hz with a temperature change of 1°

C.;

the first crystal oscillator and the second crystal oscillator are cut from a raw material of the same type and configured to be substantially equal in shape and material, and provide a combination of oscillation frequencies such that the frequency of a signal which is generated by the differential frequency generating circuit will be less than or equal to 10 kHz within a preset measuring temperature range;

the frequency counter measures the frequency of a signal received from the quartz temperature measuring probe to obtain at least eight or more significant digits; and

said quartz temperature measurement device measuring a temperature of a target medium with a precision on the order of one millionth of 1°

C. within a preset measuring temperature range.

3. The quartz temperature measurement device according to claim 2, wherein the frequency counter measures the frequency of a signal received from the quartz temperature measuring probe by a reciprocal counting method.