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WO1990011497A1 - Thermometre pour aliments - Google Patents

Thermometre pour aliments Download PDF

Info

Publication number
WO1990011497A1
WO1990011497A1 PCT/GB1990/000452 GB9000452W WO9011497A1 WO 1990011497 A1 WO1990011497 A1 WO 1990011497A1 GB 9000452 W GB9000452 W GB 9000452W WO 9011497 A1 WO9011497 A1 WO 9011497A1
Authority
WO
WIPO (PCT)
Prior art keywords
enclosure
food
food thermometer
transducer
thermometer
Prior art date
Application number
PCT/GB1990/000452
Other languages
English (en)
Inventor
Susan Margaret Mary Matthews
Peter Alan George
Derek David John Pollock
Original Assignee
S.D.A. Innovations Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by S.D.A. Innovations Limited filed Critical S.D.A. Innovations Limited
Publication of WO1990011497A1 publication Critical patent/WO1990011497A1/fr

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K13/00—Thermometers specially adapted for specific purposes

Definitions

  • the present invention relates to a food thermometer.
  • thermometers of the Mercury-in-glass type are available covering the range of temperatures necessary for the preparation and cooking of food, such thermometers are fragile, difficult to read and require detailed knowledge of the various minimum temperatures.
  • electronic thermometers do exist, they are generally laboratory tools and are unsuitable for use in a domestic kitchen. For instance, detailed knowledge of the minimum temperatures is still necessary and the constructions of such thermometers do not permit efficient and hygienic cleaning, for instance as part of the "washing-up" after preparation of food.
  • a food thermometer comprising an enclosure having an elongate portion with a tip, a temperature sensitive transducer located at the tip, at least one visual indicator located within and visible through the enclosure, a battery located within the enclosure, and a control circuit located within the enclosure and a responsive to the located within the enclosure and responsive to the transducer for actuating the or each indicator when the temperature of the transducer exceeds a predetermined value, the enclosure being sealed to prevent ingress of liquid.
  • control circuit is arranged to actuate each indicator when the temperature of the transducer exceeds a respective preset value.
  • thermometer which gives a clear and unambiguous indication of when one or more predetermined temperatures has been reached and which can readily be cleaned hygienically without the need for special measures.
  • a thermometer can be used easily and reliably by untrained personnel, such as a cook in a domestic kitchen, and allows various types of food to be prepared with little or no risk of biological contamination and food poisoning.
  • Figure 1 is a circuit diagram of a food thermometer constituting a preferred embodiment of the invention.
  • Figure 2 is an external view of the food thermometer of Figure 1.
  • a temperature-sensitive transducer 1 is connected to the inputs of a differential amplifier 2.
  • the transducer 1 is shown as a thermo-couple in Figure 1 but other types of transducer, such as thermistors and temperature sensitive semi-conductor devices, may alternatively be used.
  • the differential amplifier 2 is directly coupled and is, for instance, based on an operational amplifier providing sufficient gain so that the output signal of the differential amplifier 2 is at a level suitable for subsequent processing.
  • the differential amplifier 2 is provided with positive and negative power supply inputs which are connected to a positive power supply line 3 and a negative power supply line 4.
  • the negative supply line 4 is connected to the negative terminal of a battery 5 whereas the positive supply line 3 is connected to the positive terminal of the battery 5 via a normally open switch 6 of the "push to make/release to break" type.
  • the output of the differential amplifier 2 is connected to the non-inverting inputs of comparators 7, 8, and 9, which have power supply input terminals connected to the supply lines 3 and 4.
  • the comparators 7, 8, and 9 may, for instance, be embodied as integrated circuit comparators or operational amplifiers.
  • the comparators 7, 8 and 9 have inverting inputs which are connected to receive respective reference voltages from a reference voltage source.
  • the reference voltage source comprises a zener diode 10 connected in series with a current limiting resistor 11 between the supply lines 3 and 4 with a potential divider comprising resistors 12 to 15 connected across the zener diode.
  • the output of the comparator 7 is connected via a current limiting resistor 16 and a .light emitting diode 17 to the supply line 4.
  • the outputs of the comparators 8 and 9 are connected via current limiting resistors 18 and 19 and light emitting diodes 20 and 21 to the supply line.
  • the light emitting diodes 17, 20 and 21 may be of any desired colour and may be of the same colour or of different colours.
  • Figure 1 illustrates a thermometer having three light emitting indicators
  • fewer indicators may be provided by omitting one or two of the comparators, light emitting diodes, and associated components.
  • further comparators, light emitting diodes, and associated components may be provided.
  • Each additional comparator has its non-inverting input connected to the output of the differential amplifier 2 and its inverting input connected to a further tap on the potential- divider, for instance formed by including additional resistors in the potential divider.
  • a further comparator 22 has power supply inputs connected to the supply lines 3 and 4 and an output connected via a current limiting resistor 23 and a light emitting diode 24 to the supply line 4.
  • the comparator 22 has a non- inverting input connected to a potential divider formed by resistors 25 and 26 connected in series between the supply lines 3 and 4.
  • the comparator 22 has an inverting input connected to a potential divider formed by resistors 27 and 28 connected in series between the negative supply line 4 and the connection between the zener diode 10 and the resistor 11.
  • the comparator 22 thus compares the battery voltage with a stable voltage derived from the zener diode and illuminates the light emitting diode 24 when the terminal voltage on load of the battery 5 is sufficient to ensure correct operation of the thermometer. However, when the on load terminal voltage falls below a predetermined adequate value, the light emitting diode 24 is extinguished so as to give an indication that the battery 5 should be replaced or the thermometer should be discarded and replaced by a
  • the thermometer comprises an enclosure 30 of elongate shape having a tip 31 which is formed by or contains the temperature sensitive transducer 1.
  • the locations of the battery 5, the light emitting diodes 17, 20, 21, and 24, the switch 6, and a circuit board 32 carrying the remainder of the components shown in Figure 1 are indicated in Figure 2.
  • the light emitting diodes are located within the enclosure 30 below openings which are enclosed by transparent covers.
  • the switch 6 is located below a flexible membrane sealed to the enclosure so as to permit actuation without exposing the switch itself.
  • the enclosure 30 is therefore completely sealed against the ingress of foreign material, such as water and other liquids with which the thermometer may come into contact during use and during cleaning.
  • the enclosure 30 is preferably formed of a heat resistant plastics material having a smooth outer surface to permit easy hygienic cleaning, for instance by conventional washing-up with other food preparation utensils.
  • the switch 6 is actuated by external pressure on its membrane cover and the condition of the battery 5 is checked by observing whether the light emitting diode 24 is illuminated. If so, then the tip 31 is inserted into food at various points and left in place at each point for a few seconds to allow the transducer 1 to reach the local temperature of the food. The light emitting diodes 17, 20 and 21 are then checked for illumination so as to indicate whether the appropriate temperature has been reached throughout the food.
  • the reference voltage supplied to the inverting input of the comparator 9 corresponds to a transducer temperature of 5°.
  • the light emitting diode 21 will therefore be illuminated whenever a temperature greater than 5° is detected by the transducer 1.
  • the reference voltage supplied to the inverting input of the comparator 8 corresponds to 75° so that the light emitting diode 20 indicates whether pre-cooked food has reached its minimum temperature.
  • the reference voltage supplied to the comparator 7 is set to a value such that the light emitting diode 17 illuminates when the transducer detects a temperature of 90° or greater for checking whether raw or uncooked food has reached its minimum cooking temperature.
  • thermometer With the thermometer shown in Figures 1 and 2, it is thus possible to provide reliable and easy indication of whether predetermined temperatures for safe preparation of food have been achieved while permitting the thermometer to be cleaned hygienically and without any special precautions in a domestic or kitchen environment.
  • a food temperature of this type can readily be made insensitive to cleaning in dishwashers and the like and prevents the ingress of cleaning fluids (and also contact between food and the contents of the enclosure) .
  • Thermometers of the type shown in Figures 1 and 2 may be used in other applications.
  • the reference voltages could be chosen so that the light emitting diodes indicate whether the temperature of food is substantially correct for a baby or infant, the light emitting diodes indicating whether the food temperature is too hot, correct, or too cold.
  • the tip 31 may be formed as a blunted head to permit stirring of baby or infant food.
  • the enclosure 30 may be designed to have the appearance of a utensil such as a spoon for use by a baby or infant in order to have an educational and aesthetically attractive function for use by a baby or inf nt.
  • the reference voltages may be chosen so as to indicate the condition of cooked meat, for instance providing indications as to whether meat is rare, medium or well done.
  • a thermometer having more than three indicators so as to provide an indication that different kinds of meat have been correctly cooked for individual tastes.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Control Of Temperature (AREA)
  • Confectionery (AREA)
  • General Preparation And Processing Of Foods (AREA)

Abstract

Thermomètre pour aliments comprenant une enveloppe (30), dans la pointe (31) de laquelle se trouve un transducteur thermosensible. Des diodes électroluminescentes (17, 20, 21) sont commandées par un circuit de commande (32) qu'alimente une batterie (30) par le biais d'un commutateur (6). Ledit circuit de commande (32) compare la sortie du transducteur avec des valeurs prédéterminées et allume chaque diode électroluminescente en fonction du dépassement de la valeur prédéterminée correspondante.
PCT/GB1990/000452 1989-03-28 1990-03-26 Thermometre pour aliments WO1990011497A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB898907011A GB8907011D0 (en) 1989-03-28 1989-03-28 Food thermometer indicator
GB8907011.4 1989-03-28

Publications (1)

Publication Number Publication Date
WO1990011497A1 true WO1990011497A1 (fr) 1990-10-04

Family

ID=10654076

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1990/000452 WO1990011497A1 (fr) 1989-03-28 1990-03-26 Thermometre pour aliments

Country Status (3)

Country Link
AU (1) AU639915B2 (fr)
GB (2) GB8907011D0 (fr)
WO (1) WO1990011497A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6736086B2 (en) 2000-09-30 2004-05-18 Dolores Kaiser Food temperature measuring device with audible signal
US6945693B2 (en) 2000-09-30 2005-09-20 Kaiser Dolores C Cooking thermometer with audible alarm
US7075442B2 (en) 2003-07-07 2006-07-11 Mastrad Sa Food temperature monitoring device
TWI473983B (zh) * 2013-02-27 2015-02-21 Radiant Innovation Inc 探棒溫度計

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE9318346U1 (de) * 1993-12-01 1994-02-03 Heidl, Gerhard, 90475 Nürnberg Speisenthermometer
US7686232B2 (en) 2005-09-20 2010-03-30 Novarus Corporation System and method for food safety inspection

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3753259A (en) * 1971-08-30 1973-08-14 R Donovan Cooler and freezer failure warning system
FR2176051A1 (fr) * 1972-03-15 1973-10-26 Timm Hermann
US3927571A (en) * 1974-01-18 1975-12-23 Hobart Corp Temperature indicating device
DE2943977A1 (de) * 1978-11-06 1980-05-08 Tokyo Shibaura Electric Co Mikrowellenherd/mikrowellenofen
JPS60158325A (ja) * 1984-01-30 1985-08-19 Matsushita Electric Ind Co Ltd 温度レベル表示装置
DE8013753U1 (de) * 1980-05-22 1985-09-12 Käferlein, Christian, Dipl.-Ing., 6100 Darmstadt Temperaturmeßgerät
DE8704350U1 (de) * 1987-03-24 1988-07-21 Kühnert, Eduard, 5650 Solingen Kochlöffel, insbesondere aus Kunststoff

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4133208A (en) * 1978-01-26 1979-01-09 Parlanti Conrad A Probe-type read-out thermometer
SE437608B (sv) * 1978-08-02 1985-03-11 Inge Charlen Gustafsson Anordning for indikering av sjukdomstillstand och/eller brunst hos kor
AT376795B (de) * 1982-06-08 1984-12-27 Elkon Elektron Geraeten Elektronisches kleingeraet, insbesondere elektronisches fieberthermometer
GB2140615B (en) * 1983-03-22 1987-03-18 Standard Telephones Cables Ltd Thermistor composite
GB2162643A (en) * 1984-06-08 1986-02-05 Diehl Gmbh & Co Electronic thermometer
NL8700806A (nl) * 1987-04-06 1988-11-01 Daalderop Bv Inrichting voor het meten van de warmte-inhoud van een met vloeistof gevuld reservoir.

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3753259A (en) * 1971-08-30 1973-08-14 R Donovan Cooler and freezer failure warning system
FR2176051A1 (fr) * 1972-03-15 1973-10-26 Timm Hermann
US3927571A (en) * 1974-01-18 1975-12-23 Hobart Corp Temperature indicating device
DE2943977A1 (de) * 1978-11-06 1980-05-08 Tokyo Shibaura Electric Co Mikrowellenherd/mikrowellenofen
DE8013753U1 (de) * 1980-05-22 1985-09-12 Käferlein, Christian, Dipl.-Ing., 6100 Darmstadt Temperaturmeßgerät
JPS60158325A (ja) * 1984-01-30 1985-08-19 Matsushita Electric Ind Co Ltd 温度レベル表示装置
DE8704350U1 (de) * 1987-03-24 1988-07-21 Kühnert, Eduard, 5650 Solingen Kochlöffel, insbesondere aus Kunststoff

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS Of JAPAN, Vol. 9, No. 334 (P-417) (2057), 27 December 1985; & JP-A-60158325 (Matsushita Denki Sangyo K.K.) 19 August 1985 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6736086B2 (en) 2000-09-30 2004-05-18 Dolores Kaiser Food temperature measuring device with audible signal
US6945693B2 (en) 2000-09-30 2005-09-20 Kaiser Dolores C Cooking thermometer with audible alarm
US7075442B2 (en) 2003-07-07 2006-07-11 Mastrad Sa Food temperature monitoring device
TWI473983B (zh) * 2013-02-27 2015-02-21 Radiant Innovation Inc 探棒溫度計

Also Published As

Publication number Publication date
AU5276290A (en) 1990-10-22
GB9006723D0 (en) 1990-05-23
AU639915B2 (en) 1993-08-12
GB2229821B (en) 1993-03-24
GB2229821A (en) 1990-10-03
GB8907011D0 (en) 1989-05-10

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