GB2281797A

GB2281797A - Temperature range sensor

Info

Publication number: GB2281797A
Application number: GB9318968A
Authority: GB
Inventors: Stephen Philip Woolley
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-09-14
Filing date: 1993-09-14
Publication date: 1995-03-15
Also published as: GB9318968D0

Abstract

A temperature range sensor provided with visual 5, or audible indication that the temperature of an environment is above, below, or within acceptable, safe, or optimum limits. The sensor is provided with means for activation by conducting liquid or variation in light level or by simple switch operation. The sensor may be preset to certain temperature limits or be made adjustable. <IMAGE>

Description

TEMPERATURE RANGE SENSOR This invention relates to sensing temperatures within a specified range.

There are many situations in which a person needs to know that the temperature of an environment is within specified 'safe' limits without necessarily being aware of the precise values for these limits. Examples of such situations include the monitoring of the temperature of a baby's bath water, the interior temperature of a refrigerator or a freezer compartment or the temperature of photographic chemicals in a processing laboratory. In each example the user needs a device to indicate that the temperature is within acceptable, optimum, or 'safe' limits for the process in question. It is not necessary for the user to be aware of the actual temperature limits dictated for the process in such instances; it is sufficient to have a simple indication that the temperature is within the required range.

According to the present invention there is provided a temperature sensing device comprising a temperature measuring means so as to indicate (a) a temperature within a predetermined range, (b) a temperature below such range, and (c) a temperature above such range.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which:- Figure 1 shows the basic circuit diagram for a temperature range sensing device which is activated by contact with water or other electrically conducting liquid; Figure 2 shows the structure of a probe suitable for such a purpose; Figure 3 shows how the device might be activated by change in light level; Figure 4 shows how the device might be provided with audible rather than visual indication ofthe temperature range; and Figure 5 shows how the device might be modified to allow the permitted range to be adjusted.

Referring to the drawing figure 1 shows a sensor activated on contact with a conducting liquid. The liquid sensing probes enable the switching element, 1, connecting the OV supply to the rest of the circuit. The thermistor and resistor 2 constitute the basic temperature sensor, and the temperature range is determined by the values of the resistor chain 3. The operational amplifiers, 4, act as comparators and a visual indication ofthe temperature range is given by light-emitting-diodes 5.

Figure 2 shows an embodiment ofthe probe. The thermistor is fitted into a metal cap, 6, and connected to the circuitry by wires 9 and 10 running within the probe tubing.

The liquid sensing probes are formed by the metal cap, 6, also connected to wire 9, and a metal ring, 7, connected to wire 8. The metal cap, 6, and the metal ring, 7, are separated by a suitable insulating material.

Figure 3 shows the circuit modified to include a light activating circuit, 11, such as might be used if the sensor is to indicate a suitable temperature range in a refrigerator.

The circuit is activated by light falling onto the light sensor.

Figure 4 outlines a modification providing an audible rather than a visual output. The output transducer will produce different audible signals to indicate whether the temperature is below, within, or above the desired range.

Figure 5 shows how the upper and lower limits of the temperature range may be adjusted using potentiometers, 12.

Claims

1. A temperature sensing device comprising a temperature measuring means so as to indicate (a) a temperature within a predetermined range, (b) a temperature below such range, and (c) a temperature above such range.

2. A temperature sensing device as claimed in Claim 1 wherein the predetermined range may be preset according to the intended purpose, or be made adjustable for use in a variety of situations.

3. A temperature sensing device as claimed in Claim 1 or Claim 2 which may be activated manually by means of a switch, or by specific changes in the environment of the device such as contact with a conducting liquid or change in light level.

4. A temperature sensing device as claimed in Claim 1 or Claim 2 or Claim 3 in which the indication of temperature range is given either visually or audibly.