WO2002046711A1

WO2002046711A1 - Electronic clinical thermometer

Info

Publication number: WO2002046711A1
Application number: PCT/GB2001/005429
Authority: WO
Inventors: Mark Gostick
Original assignee: Kindertec Limited
Priority date: 2000-12-07
Filing date: 2001-12-07
Publication date: 2002-06-13
Also published as: GB0314796D0; AU2002220913A1; GB2386692A; GB0029842D0; GB2386692B; WO2002046711A8

Abstract

An electronic clinical thermometer comprises a first sensor housing portion including at least one temperature sensor adapted to produce an output signal indicative of temperature, a second display housing portion including a visual display, and a third connecting link portion which connects the first portion to the second portion in a spaced arrangement to define a space between the first portion and second portion into which a part of a users hand can be inserted, and an electronic circuit located at least partially within the first, second and/or third portions which receives the output signal from the or each sensor and processes the received output signal to produce a display drive signal which causes an indication of the measured temperature to be produced on the display. This makes it simple to hold the thermometer whilst taking measurements.

Description

ELECTRONIC CLINICAL THERMOMETER

This invention relates to improvements in thermometers, and in particular to electronic clinical thermometers.

It is well known that a measurement of a patient's temperature can provide a good indication of the health of the patient. This is especially important with the young - up to the age of 3-4 years - who are unable to express themselves. This may also be true with elderly or infirm patients. A high temperature may indicate a fever, and depending on the exact temperature may indicate that a doctor should be called immediately or simply that attempts should be made to lower the patient's temperature.

Many types of clinical thermometers are presently available. Historically the most common type of clinical thermometer used a glass column containing mercury which expanded up the column with increasing temperature. The height of the column indicated the temperature. Recent developments have led to the demise of this type of thermometer which is widely regarded as being dangerous to use and also difficult to read accurately .

More recent clinical thermometers employ a sensing element such as a thermocouple or an infrared based sensing element which generates a voltage dependent on temperature. An electronic circuit housed within the thermometer converts the generated voltage into a drive signal for a numeric display. The display may show the sensor temperature in either degrees Centigrade or degrees Fahrenheit. An example of such a device is known from GB 2117579.

Other temperature sensing technologies have also been employed. One such alternative is the use of an IR detector as the sensor instead of a thermocouple. This can, in some circumstances offer faster response times although the technology usually makes the thermometer more expensive.

For all the other types of sensor, measurements can be made from a wide number of locations on the patients body. The most common measurement point recommended are in the mouth (oral measurements) or under the armpit (axilliary measurement) . This is often difficult, especially with small children and babies who usually resist any attempts to take measurement using a thermometer. Many health practitioners also recommend oral measurements should not be taken on young children, and underarm measurements require the child's clothes to be moved to take measurements which is at best inconvenient.

The shape of the majority of prior art thermometers also makes measurements of the temperature of children difficult. They usually comprise a body to be gripped in the hand and an elongate probe tip which extends from the body. The action of putting the tip in the child's mouth or under the arm can be quite intimidating to the child.

An object of the present invention is to ameliorate some of the problems with prior art clinical thermometers.

In accordance with a first aspect, the invention provides an electronic clinical thermometer comprising: a first sensor housing portion including at least one temperature sensor adapted to produce an output signal indicative of temperature; a second display housing portion including a visual display; a third connecting link portion which connects the first portion to the second portion in a spaced arrangement to define a space between the first portion and second portion into which a part of a users hand can be inserted; and an electronic circuit located at least partially within one or more of the first, second and third portions which receives the output signal from the or each sensor and processes the received output signal to produce a display drive signal which causes an indication of the measured temperature to be produced on the display.

The invention therefore provides a thermometer which fits around a part of the hand, for example held between the thumb and forefinger, of a user making it simple to hold whilst taking measurements. The first, second and third portions may define a single housing. Alternatively, the first or second portions may be separate whilst the third portion forms an integral part of the first or second portions.

The connecting portion may comprise a stem adapted in use to be located between at least two adjacent fingers of the users hand (for example between the second and third fingers) or between the thumb and forefinger whereby the sensing portion is located on the palm side of the hand and the display portion is located on the back side of the hand. The stem or a part of the thermometer surrounding the stem may be made from a rubber material which helps the thermometer "grip" the users hand.

In use, the thermometer when worn on the hand can be pressed onto a part of the patient's body by the palm side of the hand or fingers whilst allowing the display to be read by looking at the back side of the hand. The thermometer may include a pressure sensitive switching means whereby the thermometer is activated (e.g. starts to take a reading) by the action of pressing the sensor housing portion onto the surface to be measured. The invention is especially suitable for taking measurements of temperature from a patient's forehead by simply pressing the palm side of the hand onto the forehead. This is a very natural action and will not intimidate a young child as is common when using conventional thermometers. Alternatively, underarm measurements can be made by the user sliding the hand under the armpit. It is simple to feel when the sensing portion is correctly located.

The sensing portion may define a substantially smooth sensing face into which, or onto which, the or each sensor is located. The sensor may be a thermocouple or a device sensitive to infrared radiation, or perhaps some other form of sensing device.

Each sensor may comprise a thermocouple which is arranged to contact the surface whose temperature is to be measured when the sensing surface is pressed against the skin. The sensing face may be wholly or at least partially of resilient or conformable material to allow it to conform to the contours of the surface against which it is pressed. The sensors may be spaced in an even pattern around the sensing face or at random spacing where a single sensor is provided this may be located substantially at the centre of the sensing face. Of course, in an alternative the entire sensing face may form part of the sensors itself. Also, other sensors may be employed, such as infa-red temperature sensors which produce an output representative of the amount of infa-red radiation emitted from a surface.

The display portion may also define a substantially flat face which supports the display such as a liquid crystal display. The viewing face of the display may conveniently be flush with the rest of the face of the display portion. In an alternative, the face and the display may define a concave or perhaps convex surface. The display is preferably parallel to the sensing face. The display portion may conveniently house the electronic circuit which is connected to the or each sensor by one or more electrical wires. The or each wire may conveniently pass through the third connecting portion. The display portion may also accommodate a battery making the thermometer self contained. A button cell battery is preferred as it maintains the low profile of the thermometer and minimises its bulk. This is important in producing an attractive non-aggressive design that will not intimidate children when used to take temperature measurements.

The display may be rotatable relative to the sensor portion. This may be achieved by making the first portion rotate relative to the second portion. An advantage of making the display rotatable is that it allows the user to orient the display to the ideal position for reading when in use.

The display may present the measured temperature as numerical data, i.e. 36²C or as another form of visual data such as an array of coloured lights which are selectively illuminated depending on temperature measured.

It will, of course, be appreciated that many modifications and variations may be made. For example, the connecting portion may comprise a band (either stretchable or non-stretchable) which allows the users fingers or palm to support the sensing portion and display portion on either side of the hand. The connecting portion may alternatively form an integral part of a moulding defining the first and/or second housing portions.

In one modification, the first and second portions may be collapsed together when not in use and pulled apart to provide the space for accommodating the part of the hand when in use. The action of pulling the two portions away from one another may be used to turn on the thermometer electronic circuit. Also, the electronic circuit may be located in the sensing portion rather than the display portion. It is preferred to provide it in the display housing portion as this minimises the bulk of the first sensing portion.

In a further modification, the temperature indication may be held on the display either for a preset time after a measurement is made or until cleared by the user. A button may be provided for clearing the display. This is especially beneficial for taking axillary measurements as the display may not be visible whilst measurements are taken.

An audible alarm may also be provided which issues an audible signal to indicate that a successful reading has been taken. It may also issue a warning signal if the measured temperature falls outside as a predetermined safe range. For instance, the alarm may be raised if the measured temperature indicates a body temperature greater than 38 degrees Centigrade.

The device may be battery operated and may include a battery within the first portion, second portion and/or third portion such as a button cell or perhaps AA or AAA battery.

There will now be described, by way of example only, one embodiment of the present invention with reference to the accompanying drawings of which:

Figure 1 is a perspective view of a first embodiment of a clinical thermometer in accordance with the present inventions .

Figure 2 is a perspective view of an alternative embodiment of a thermometer in accordance with the present invention in (a) a closed inoperative position and (b) an open operative position, and (c) shows the display rotated into a different alignment.

Figure 3 is a view of the thermometer in its position of use on a users hand.

Figure 4 is an illustration of the thermometer in use to measure temperature of a childs forehead.

Figure 5 is an illustration of an alternative use of the thermometer to measure the underarm temperature of a child.

Figure 6 is a schematic of the electronic circuit included in the thermometer of Figure 1.

As illustrated in Figure 1, the thermometer 100 comprises two generally disc shaped housing portions 101 , 102 connected by a central stem 103 extending from an inward facing side of each disc. This central stem 103 supports the two discs in parallel spaced arrangement with sufficient spacing to accommodate the fingers of a users hand between the discs. Typically, the central stem 103 will be passed down between the index finger and middle finger of the hand, or perhaps the thumb and index finger. This is possible by making the length of the stem approximately equal to the thickness of the average persons fingers.

A first one 102 of the disc-like portions defines a sensor housing 102 that has an outer face 106 (not shown) which in use extends away from the palm side of the hand. Located at spaced intervals within this face are a number of thermocouple sensing elements (not shown) . The face accommodating the elements is made from a resilient or mouldable material, such as hydrogel, to permit the face to conform itself to a surface onto which it is pressed to ensure optimum contact between the thermocouple elements and the surface being measured.

The second disc-like portion 101 accommodates an electronic processing circuit and a liquid crystal display panel 104 on which a numerical representation 105 of the temperature measured by the thermocouple is displayed. The display panel is incorporated into an outer-facing face of the disc.

In use, the thermometer is placed on a users hand 300 with the stem between the fingers of the hand as shown in Figure 3 of the accompanying drawings. When in this position of use on a users hand the display can be easily read by observing the back of the hand. This allows a measurement to be made in a natural way by placing the hand onto the surface to be measured, such as a child's forehead (as shown in Figure 6 of the accompanying drawings) or under the childs arm ( as shown in Figure 4 of the accompanying drawings) . This brings the sensing elements into contact with the skin surface whilst allowing the display to be read.

Electronic wires (not shown) extend from the thermocouples in the first portion through the connecting stem to the electronic circuit in the second display portion. This second display portion also accommodates a small button cell battery (not shown) .

Figure 6 of the accompanying drawings shows the circuit of the thermometer. The thermocouples 200 are connected in series by connecting wires 201 to an input side of the electronic circuit which includes a sensitive pre-amplifier 202. Connecting the sensors in series allows a maximum value of the thermocouple output to be measured allowing for differences in contact between the thermocouples and surface to be accommodated. In a modification, the voltage produced by each thermocouple may be separately amplified and the "best" value used for subsequent processing. By "best" we may mean the highest ready for readings above normal body temperature or the lower reading for temperatures below normal body temperature.

The analogue output of the pre-amplifier 202 is fed to an analogue to digital converter 204 driven by a quartz crystal oscillator 205 which converts the amplified voltage into a digital measurement signal indicative of temperature. This digital value is passed to a central processing unit 206.

The central processing unit 206 analyses the measured value, which may change over time as the reading stabilises. When a satisfactory reading is received by the processor 206, for instance identified by a steady state value over a few seconds time span, the digital measurement signal is passed to a numerical display driver circuit 207.

The display driver circuit 207 converts the digital measurement signal into a suitable drive signal (or signals) for driving the liquid crystal display 104, 208 to produce a numerical display of the measured temperature .

A second display 209, in the form of a set of lights of different colour is also provided. One or more green lights are provided, at least one red light and at least one blue light. For measured temperatures in a normal range of body temperature the green light is illuminated whilst the others are extinguished. For higher temperatures the red light may be lit. This provides a very simple display of the temperature in a way which can be readily understood. A red light indicates the body temperature is too high. The blue light is lit to indicate that the measured temperature is too low. A separate display drive 210 is used to drive the colour lights.

The circuit also includes a piezo-electric buzzer (not shown) . This produces an audible alarm which is activated for temperatures corresponding to a red or a blue light. The alarm is also driven by the central processing unit to provide an audible beep signal when a satisfactory reading has been obtained.

An alternative embodiment of a thermometer is illustrated in Figures 2(a) to 2(c) of the accompanying drawings. For clarity, the same reference numerals have been used to indicate like parts as the embodiment of Figure 1.

In this arrangement the first portion 102 housing the sensors is free to move towards, and be at least partially accommodated within, the second portion 101 housing the display 104. This allows the thermometer to be compressed when not in use as shown in figure 2(a) . To use the thermometer the two portions are pulled apart to provide the spaced therebetween needed to accommodate the users fingers. This action also acts to turn on the electronic circuit and energise the display. In a further refinement, which can also be incorporated into the design of Figure 1, the display portion may be rotated relative to the sensor portion.

Claims

1. An electronic clinical thermometer (100) comprising: a first sensor housing portion (102) including at least one temperature sensor adapted to produce an output signal indicative of temperature; a second display housing portion (101) including a visual display (104) ; a third connecting link portion (103) which connects the first portion (102) to the second portion (101) in a spaced arrangement to define a space between the first portion (102) and second portion (101) into which a part of a users hand can be inserted; and an electronic circuit located at least partially within one or more of the first portion (102), the second portion (101) and the third portion (103) which receives the output signal from the or each sensor and processes the received output signal to produce a display drive signal which causes an indication of the measured temperature to be produced on the display.

2. The thermometer of claim 1 in which the first, second and third portions (102, 101 , 103) comprise parts of a single housing.

3. A thermometer according to claim 1 or claim 2 in which the connecting portion (103) comprises a stem adapted in use to be located between at least two adjacent fingers of the users hand whereby the sensing portion is located on the palm side of the hand and the display portion is located on the back side of the hand.

4. A thermometer according to any preceding claim which includes a pressure sensitive switching means whereby the thermometer is activated Ϊ2 (e.g. starts to take a reading) by the action of pressing the sensor housing portion onto the surface to be measured.

5. A thermometer according to any preceding claim in which the sensing portion defines a substantially smooth sensing face into which or onto which the or each sensor is located.

6. A thermometer according to any preceding claim in which the or each sensor comprises a thermocouple which is arranged to contact the surface whose temperature is to be measured when the sensing surface is pressed against the skin.

7. A thermometer according to claim 6 in which the sensing face is at least partially of resilient or conformable material to allow it to conform to the contours of the surface against which it is pressed.

8. A thermometer according to any preceding claim in which the display portion (102) houses the electronic circuit which is connected to the or each sensor by one or more electrical wires.

9. A thermometer according to any preceding claim in which the display (104) is rotatable relative to the sensor portion.

10. A thermometer according to any preceding claim in which the first and second portions (102, 101) may be collapsed together when not in use and pulled apart to provide the space for accommodating the part of the hand when in use.

11. A thermometer according to claim 10 in which the action of pulling the first and second portions (102, 101) away from one another turns on at least a part of the thermometer electronic circuit.