Wireless temperature-sensing system inclusive of thermally-responsive oscillator

• US 4,340,796 A
• Filed: 08/29/1979
• Issued: 07/20/1982
• Est. Priority Date: 08/31/1978
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Yamaguchi, Masumi, Kumagai, Yoshimi, Kawabata, Kenji
• Primary Examiner(s): Truhe, J. V.
• Assistant Examiner(s): George, Keith E.
• Application Number:
  US06/070,730
• Time in Patent Office: 1,056 Days
• Field of Search: 219/10.55 B, 219/10.55 E, 219/10.55 D, 219/516, 310/311, 310/341, 310/343, 73/339 A, 73/352, 324/61 QL, 324/61 QS
• US Class Current: 219/713
• CPC Class Codes: G01K 1/024 for remote indication
• CPC Class Codes: G01K 2207/06 for preparation purposes
• CPC Class Codes: G01K 7/32 using change of resonant frequency of a crystal
• CPC Class Codes: H05B 6/6411 the supports being rotated
• CPC Class Codes: H05B 6/6452 the sensors being in contact with the heated product
• CPC Class Codes: H05B 6/6467 using detectors with R.F. transmitters
• CPC Class Codes: H05B 6/6482 combined with radiant heating, e.g. infrared heating

Abstract

A wireless temperature-sensing assembly adapted for a cooking apparatus such as a microwave oven, comprises a wireless communication element and a sensing probe. The wireless communication element provides electromagnetic waves over an oven cavity of the cooking apparatus. The sensing probe selects a particular frequency of the electromagnetic waves. The sensing probe contains an oscillator element resonance frequencies of which vary depending on the surrounding temperature. The wireless communication element further receives and detects the particular frequency of the electromagnetic waves defined by the selecting means. In a specific form, the wireless communication element provides the electromagnetic waves the frequencies of which vary from time slot to time slot. The oscillator element may be composed of crystal, ceramic, or the like. The resonance frequencies of the oscillator element change due to variation in its number of proper vibrations dependent on the surrounding temperature.

Claims

1. Wireless temperature sensing means for monitoring a temperature within a cooking apparatus, comprising:

transmitter means for propagating electromagnetic waves within said cooking apparatus over a range of selectively variable frequencies, the said frequencies varying by predetermined increments upon the respective lapses of corresponding predetermined increments of time over which given discrete frequencies exist;

resonant circuit means having a resonant frequency variable linearly in accordance with a monitored temperature value in said cooking apparatus and being devoid of a source of power for selectively responding to a particular frequency of said given discrete frequencies of said propagated electromagnetic waves which is representative of said monitored temperature value and repropagating a response wave having that particular frequency over a subsequent interval of time; and

detection means, responsive to said response wave over a sampling interval coincident with said subsequent interval of time for determining said particular frequency as a measure of monitored temperature value.

2. The wireless temperature sensing means of claim 1, wherein said resonant circuit means comprises oscillator element means having a resonant frequency varying linearly in response to variations in monitored temperature value in combination with inductance and capacitance tuning means for maximizing the response of said resonant circuit means to said particular frequency of said propagated electromagnetic waves.

3. The wireless temperature sensing means according to claim 2, wherein said oscillator element means is constructed of a material selected from the group consisting of crystal and ceramic having resonant frequencies linearly variable with respect to temperature.

4. The wireless temperature sensing means of claim 1, wherein said detection means includes:

gated frequency counter means, enabled over said sampling interval, for providing a count representative of said particular frequency; and

means responsive to said count for providing an output signal representing said monitored temperature value.

5. The wireless temperature sensing means of claim 4, which further includes display means responsive to said output signal for displaying said monitored temperature value.

6. The wireless temperature sensing means according to claim 4 further comprising control means responsive to said output signal for controlling said cooking apparatus.

7. The wireless temperature sensing means according to claim 6, wherein said control means comprises:

power source means for supplying power to said cooking apparatus; and

power control means for controlling the power supplied from said power source means to said cooking apparatus.

8. The wireless temperature sensing means according to claim 7, which further comprises display means responsive to said output signal provided by said detection means for displaying said monitored temperature value.

9. The wireless temperature sensing means according to claim 7 or 8, wherein said control means further comprises:

input means for introducing information representing a desired temperature of said cooking apparatus into said control means;

storage means for retaining said desired temperature information; and

comparing means for determining the difference between said desired temperature and said monitored temperature for providing a power control signal to said power control means in the absence of said difference to terminate the supply of power from said power source means to said cooking apparatus.

10. The wireless temperature sensing means of claim 1, wherein said resonant circuit means comprises oscillator element means having a resonant frequency varying linearly in response to variations in monitored temperature value in combination with inductance and capacitance tuning means for maximizing the response of said resonant circuit means to said particular frequency of said propagated electromagnetic waves;

and

wherein said detection means includes;

gated frequency counter means, enabled over said sampling interval, for providing a count representative of said particular frequency; and

means responsive to said count for providing an output signal representing said monitored temperature value.

11. The wireless temperature sensing means of claim 10, which further includes display means responsive to said output signal for displaying said monitored temperature value.

12. The wireless temperature sensing means according to claim 1, wherein said cooking apparatus is a microwave oven.

13. Cooking control means for detecting the difference between a monitored cooking temperature value and a preset cooked temperature value of a foodstuff in a cooking apparatus and controlling said apparatus as a function of the said difference in temperatures, comprising:

transmitter means for propagating electromagnetic waves within said cooking apparatus over a range of selectively variable frequencies, the said frequencies varying by predetermined increments upon the respective lapses of corresponding predetermined increments of time over which given discrete frequencies exist;

resonant circuit means having a resonant frequency variable linearly in accordance with a monitored temperature value in said cooking apparatus and being devoid of a source of power for selectively responding to a particular frequency of said given discrete frequencies of said propagated electromagnetic waves which is representative of said monitored temperature value and repropagating a response wave having that particular frequency over a subsequent interval of time; and

detection means, responsive to said response wave over a sampling interval coincident with said subsequent interval of time for determiming said particular frequency as a measure of said monitored temperature value;

said detection means providing an output signal representative of said monitored cooking temperature value;

comparison means responsive to said output signal and including a reference parameter representative of said preset cooked temperature value for comparing said monitored cooking temperature value with said preset cooked temperature value for generating a representative temperature difference signal therebetween; and

control means responsive to said temperature difference signal for controlling the cooking of said foodstuff by said cooking apparatus as a function of said temperature difference.

14. The wireless temperature sensing means of claim 13, which further includes display means responsive to said output signal for displaying said monitored cooking temperature value.

15. The cooking control means in accordance with claim 13 or 14, wherein said resonant circuit means comprises oscillator element means having a resonant frequency varying linearly in response to variations in monitored temperature value in combination with inductance and capacitance tuning means for maximizing the response of said resonant circuit means to said particular frequency of said propagated electromagnetic waves.

16. The cooking control means in accordance with claim 13 or 14, wherein said detection means includes:

gated frequency counter means, enabled over said sampling interval, for providing a count representative of said particular frequency; and

means responsive to said count for providing an output signal representing said monitored temperature value.

17. The cooking control means in accordance with claims 13 or 14, wherein said resonant circuit means comprises oscillator element means having a resonant frequency varying linearly in response to variations in monitored temperature value in combination with inductance and capacitance tuning means for maximizing the response of said resonant circuit means to said particular frequency of said propagated electromagnetic waves;

and

wherein said detection means includes;

gated frequency counter means, enabled over said sampling interval, for providing a count representative of said particular frequency; and

means responsive to said count for providing an output signal representing said monitored temperature value.

18. The cooking control means in accordance with claim 13 or 14, wherein:

said comparison means further comprises input means for introducing a desired preset cooked temperature reference parameter of said foodstuff therein; and

said control means de-energizes said cooking apparatus when said temperature difference approaches zero.