DETECTOR WITH INDICATOR LIGHT

Abstract: A detector (10) having a base (11) and a cover (12) the base having about part of its periphery a surface (15) which is transparent or translucent and having located internally at least one source of illumination (31, 32, 33) which, when operating can effect the illumination of the surface (15) to enable ready visual identification of the operation of the detector.

Description: DETECTORWITH INDICATORLIGHT This invention relates to an improved detector and in particular to a detector which may be a thermal, smoke or other detector adapted to be located in a building, normally on a ceiling thereof• In this specification we shall not qualify the application of the detector, unless this is specific, and the term can relate to any of the types of detectors commonly used. It is normally a requirement of the relevant authorities that buildings be provided with detectors, and conventionally, these are ceiling mounted, and are adapted to react when the relevant parameter changes to a value which is predetermined. The detectors may simply operate to close a circuit, which provides an alarm or other function at a remote position, or they may be intelligent in that they contain a micro processor and are continually interrogated from a remote position so that their status can be ascertained. This second form is becoming more common as it ensures that the detector is in fact operative whereas in the passive forms of detector, reliance has to be placed on the fact that the detector will operate when an alarm condition occurs. Many authorities demand that detectors must have an indicator which shows when the detector is operative and such indicators can conventionally be LED's but they could also be incandescent SUB S TITUTESHEET globes or even discharge devices. A problem that has been found with the current indicator devices is that they are normally located either on the body of the detector itself, or on the detector-base and their illumination can be very directionally selective so that it can be very difficult to see whether they are in fact illuminated or not. Very often the maximum output can be in a narrow cone angle and once it goes beyond that angle, then it is difficult if not impossible to see whether the indicator is in fact illuminated and thus an observer would need to be very close to the detector to ascertain its status. The principal object of the present invention is to provide a detector in which this difficulty is minimised. It is also an object to provide a detector which is aesthetically pleasing, simple to locate and service and yet economic to manufacture. In its broadest sense the detector of the invention has a base having about part of its periphery a surface which is transparent or translucent and having located internally at least one source of illumination which can effect the illumination of at least a part of the surface. In a preferred form of the invention the surface can effectively be at an angle which is directed outwardly from the base and thus, when the base is positioned on the ceiling or the like, is directed downwardly and outwardly. In a specific preferred form there may be one or more light sources, the output of which are directed to various positions about the base, so that illumination is achieved over effectively the whole periphery of the base. In order that the invention may be more readily understood we shall describe one particular form of detector made in accordance with the invention in relation to the accompanying drawings, in which:- Figure 1 is a perspective view of one form of detector showing how it would be normally mounted; Figure 2 is a plan view of one form of base which might be used with the invention; Figure 3 is a side elevation of the base of Figure 2; and Figure 4 is a schematic view of one possible form of circuit board adapted to be located in the base. As is conventional the detector 10 is shown to be generally circular in plan, although it will be understood that the aspects of the invention can be applied to detectors of different shapes. The detector has a base 11 and a cover 12 and the base itself may be made of two components 13, 14 as will be described hereafter. The components are preferably made of moulded synthetic plastics materials, for cheapness of manufacture of large quantities of components, and the component 14 of the base is made of a plastics material which is transparent or translucent. Around the periphery 15 of the component 14 of the base there is what is effectively a bevel which is formed integral with the base but which is generally downwardly and outwardly directed when the base is mounted on a ceiling, as shown in Figure 1. The component 13, which may be an annular ring which fits over the component 14 and abuts a shoulder 16 thereon and the cover 12 are solid and light impervious. This bevel 15 is so arranged that if the base is illuminated from the inside then the bevel will also become illuminated. The cover 12 is designed to permit operation of the type of detector to be used and again is of an opaque material. Mounted in the base is a circuit board 30 comprising the necessary circuitry for operation of the detector. The form of the circuit board is constrained by the shape and size of the detector and the circuitry will, of course, depend on the type of the detector. It is preferred that the base and cover are readily attached one to the other and that any necessary electrical connections which need to be made between components on the different parts are made automatically as they are connected. For example, if the transducer is mounted on the cover, then its connection to the circuit can be by way of complimentary connectors on the base 11 and the cover 10. Shown on the board are light sources 31, 32, 33 which are adapted to provide the required illumination. For simplicity in description these will be considered to be light emitting diodes (LEDs) although, as indicated earlier, other forms of light source could be used. As illustrated the circuit board 30 is in the form of an arc of a circle adapted to be located adjacent the periphery of the detector and is connected to the base 11. Two of the LEDs, 31, 32 are adjacent the edge of the board and are directed outwardly so as to terminate inwardly of the base adjacent the position of the bevel 15 and the third 33 can be generally inwardly directed. Associated with the base and this third LED there can be a light pipe 34, which can simply be a rod of transparent plastics material which has one end adjacent the LED 33 and the other end adjacent the inside of the base substantially bisecting the obtuse included angle between the other two LEDs*, 31, 32. That is the effective outputs from the LEDs' are located more or less equiangularly about the periphery of the base. The actual location may not be equiangular as the spacing of the first two LEDs' are dependant upon the size of the circuit board and these may, for example, be at approximately 90 degrees subtended angle to the centre of the base from each other rather than 120 degrees, which would be required for the spacing to be equiangular. Nevertheless we have found that by the use of such an arrangement the indication can be readily seen from any position around the detector and the arrangement of the bevel can be such as to permit the provision of relatively wide cone angle over which the light can be seen. This means that a person entering an area where a detector or a number of detectors are located can readily see whether the or which detector has its indicator illuminated and thus which detector is providing a fault signal. It may be possible to chemically coat the body with a material such as a fluorescent paint or other light enhancing material. If, for example a fluorescent paint is used this will absorb light from the illumination source and retransmit it in a narrow frequency band which can readily be seen. Also whilst we have described the invention in relation to a circular detector having three LEDs it will be understood that the same arrangement can be provided for different shaped detectors and for different arrangements of light sources. For example we could use a single light source and a number of light pipes which terminate at different positions about the periphery of the device. Alternatively we could in fact use a number of light sources which are physically located adjacent the periphery of the base and which are in electrical connection to the circuit. Further we could use detectors of different shapes, for example a square or rectangular detector which means whereby each of the sides of the detector could be illuminated.

Claims: We claim: 1. A detector (10) having a base (11) having about part of its periphery a surface (15) which is transparent or translucent and having located internally at least one source of illumination (31,32,33) which can effect the illumination of at least a part of the surface (15). 2. A detector as claimed in claim 1 in which the surface (15) is at an angle to the surface on which the detector is mounted. 3. A detector as claimed in claim 1 or claim 2 wherein there is a circuit board (30) in or on the base (11) on which there is mounted at least one light source (31,32,33). 4. A detector as claimed in claim 3 wherein there are a plurality of light sources. 5. A detector as claimed in claim 3 wherein there is a light source (33) and associated therewith at least one light pipe (34) terminating close to the surface (15). 6. A detector as claimed in any preceding claim wherein the base (11) is circular in plan and the surface (15) is peripherally located. 7. A detector as claimed in claim 6 wherein the surface (15) is an annular bevel. 8. A detector as claimed in any preceding claim having a cover (12) and an electronic circuit board mounted within the detector. 9. A detector as claimed in claim 8 wherein part of the circuitry is located in the cover and wherein the electrical connections with the circuit board are made on connection between the cover and the base. 10. A detector as claimed in any preceding claim wherein the surface (15) is treated to effect light enhancement.

Inventors: HELLEWELL GEOFF, HELLEWELL, GEOFF
Applicants: HARDIE JAMES BUILDING SERVICES, JAMES HARDIE BUILDING SERVICES & TECHNOLOGIES LIMI
Application year: 1992
Main classification: F21V23
IPC codes: G08B17