Panel/chassis mounted indicator lamps

Abstract: A panel/chassis mounting indicator lamp comprising a first part in the form of a bush (114), of resilient material for insertion, in use, lengthwise into an aperture (112) in a panel/chassis (113), the bush (114) having a longitudinal through bore (115) and an outwardly extending shoulder (128) at or adjacent one end for limiting the depth of insertion of the bush (114) into the aperture (112). A second part in the form of an LED (110) has a solid plastics body which is received, in use, within the bush bore (115). The outer peripheral surface of the LED body engages with the bush such as to distort the bush so that it is expanded, on the side of the panel/chassis aperture opposite to that engaged by the shoulder (128) sufficiently to prevent withdrawal of the bush from the chassis aperture (112) and to cause the bush to grip the LED (110) to prevent withdrawal of the LED therefrom.

Description: The present invention relates to indicator lamps of the type adapted for panel mounting (References to panel mounting include chassis mounting). Many different means of mounting indicator lamps in a panel or chassis are known. The traditional method of fixing such lamps has been for the lamp to include an outer housing which is inserted through a hole in the panel/chassis, the extent of projection being limited by a shoulder on this housing which engages one side of the panel/chassis. The end of the housing which projects from the other side of the panel/chassis has an external screw thread which receives a correspondingly screw-threaded retention nut. Among the numerous disadvantages of this traditional means of fixing are that the sealing between the lamp and the panel/chassis is unreliable and that access to the back (other side) of the panel/chassis is necessary to secure the lamp in its operational position. The problem of sealing was addressed in UK 1530304 (Robert Frederick Oxley) and, in accordance with that patent, there was provided a sealing device comprising a first part of resilient material for insertion, in use, lengthwise into a chassis aperture, the first part having a shoulder adjacent one end for limiting the depth of insertion of the first part into the aperture, and a second part for insertion, in use, into a corresponding shaped first bore in the first part which extends lengthwise from the shouldered end of the first part, one end of the second part carrying an outwardly directed detent for expanding the first part, on the side of the chassis opposite to that engaged by the shoulder, sufficiently to inhibit subsequent withdrawal of the first part from the chassis aperture, at least a portion of the second part being transparent or translucent such that light may pass from one side of the chassis to the other. For use as a lamp, the latter sealing device was designed such that the second part comprised a solid cylindrical body portion of diameter slightly smaller than that of the bore in the first member and which has an annular detent at its one end. The other end of the body was formed with a lens portion having a convex surface and a shoulder portion for engaging the projecting end of the first part. The cylindrical body forming the second part was received in a blind bore in one end of the first part. The opposite end of the first part had a further blind bore in which was positioned a light emitting device, such as an LED. The latter device was fixed in the further blind bore by a clip or a screw. Thus, in the lamps originally envisaged in UK 1530304, the sealing means using the annular, outwardly directed detent was applied to the lens of the lamp or to a holder for the lens and in no way with the light emitting device itself. Another design was our BARB (Registered Trade Mark) CONE-LOCK range of LED indicator lamps. A typical example of our latter range of indicator lamps is illustrated in Figures 1 and 2 of the accompanying drawings. An initially cylindrical bush 10 of a resilient plastics material, such as PTFE, having a peripheral shoulder 12 at one end, is inserted into a circular aperture in a panel or chassis 14. This corresponds to the "first part" of UK 1530304. A cylindrical bodied LED 16 (whose periphery is indicated by chain lines in Figs. 1 and 2) is fixed securely within a cylindrical longitudinal bore in an outer rigid metal sleeve 18. A lens end 24 of the LED projects from one end of the metal sleeve 18 and terminals 20, 22 of the LED project from the opposite end of the sleeve 18. The LED is fixed within the metal sleeve 18 by adhesive and/or suitable potting compound. Whereas the inner peripheral surface of the metal sleeve 18 is purely cylindrical, the outer periphery is formed firstly with an outwardly directed shoulder 24a at one end, for engaging the bush 10, and secondly with an outwardly directed annular detent 26 located approximately midway along the length of the sleeve 18. In use of the latter lamp device, the PTFE bush 10 is first inserted into the panel/chassis aperture and the metal sleeve (containing the LED) is then slowly and gently pushed through the bush 10 (terminal end first) so that the detent 26 distorts the bush 10 to assume the positions shown in present Figures 1 and 2 and thereby resist subsequent withdrawal. Imperfect holes can be improved by the use of smear of silicone grease on the PTFE bush prior to insertion. This arrangement has been very successful commercially and provides an excellent weatherproof seal between the lamp and the panel/chassis. Another lamp device is known from DE-A- 3009425 which makes use of a radially projecting flanged part formed at the rear end of an LED. After the LED and a surrounding bush of resilient material have been inserted together into a panel aperture, the LED is then moved backwards relative to the bush so that the flange on the LED expands the bush to hold the bush and LED in position. The present invention seeks to provide a lamp having even better sealing properties while using an modified LED and being cheaper and easier to manufacture than the existing devices. In accordance with the present invention, there is provided a panel/chassis mounting indicator lamp comprising a first part in the form of a bush of resilient material for insertion, in use, lengthwise into an aperture in a panel/chassis, the bush having a longitudinal through bore and an outwardly extending shoulder at or adjacent one end for limiting the depth of insertion of the bush into the aperture, and a second part in the form of an LED having a solid plastics body which is received, in use, within the bush bore, the outer peripheral surface of the LED body engaging with the bush such as to distort the bush so that it is expanded, on the side of the panel/chassis aperture opposite to that engaged by the shoulder sufficiently to prevent withdrawal of the bush from the chassis aperture and to cause the bush to grip the LED to prevent withdrawal of the LED therefrom, wherein the LED is unmodified, and the outwardly extending shoulder of the bush is formed, so that in use, a portion of the bush will project beyond the aperture on the opposite side of the panel/chassis to that engaged by the shoulder, there being formed within the bush bore an internal projection which is adapted to be engaged by the hemispherical end of the LED when the latter is inserted into the bush bore whereby to outwardly distort the projecting portion of the bush sufficiently to prevent withdrawal of the bush from the panel/chassis aperture. In one embodiment, the internal projection comprises an annular flange disposed at the end of the bush which projects beyond the panel/chassis aperture. In another embodiment, the internal projection comprises a radially inwardly directed shoulder in the bush bore disposed at a position within said portion which, in use, projects beyond the panel/chassis aperture. Advantageously, in addition to said shoulder, the bush is formed with an annular flange disposed at the end of the bush which projects beyond the panel/chassis aperture, the flange serving to retain a lens disc within the bush in front of said hemispherical end of the LED. The invention is described further hereinafter, by way of example only, with reference to the accompanying drawings, in which:- Figs. 1 and 2 are front and side views of a known panel/chassis mounting indicator lamp; Fig. 3 shows in side elevation a typical LED; Fig. 4 is a sectional side view illustrating the two main components of one embodiment of a panel/chassis mounting indicator lamp assembly in accordance with the present invention, but prior to assembly of the components together; Fig. 5 corresponds to Fig.4 but shows the components in side elevation; Fig. 6 is a side elevation showing the components of Figs. 4 and 5 in their assembled positions; Fig. 7 is a sectional side view illustrating the two main components of a second embodiment, prior to assembly of the components together; Fig. 8 corresponds to Fig. 7 but showing the components in side elevation; and Fig. 9 is a side elevation showing the components of Figs. 5 and 6 in their assembled positions. Fig.1 shows a typical LED 110 having a cylindrical body 116, a hemispherical lens portion 118 at one end, an outwardly extending peripheral flange 120 at the other end, and terminal pins 122. By use of a bush component described hereinafter, the LED 110 can be mounted in an aperture 112 of a panel 113 (Fig.2) without any structural modification whatsoever being required to the LED. A first embodiment of the bush component 114 is shown in section in Fig.2. The bush 114 comprises a cylindrical body 122, of a resilient plastics material such as PTFE, having at its one end an inwardly directed annular flange 124. Extending from said one end of the bush, the bush is formed with a reduced diameter portion 126 which terminates in a radial shoulder 128. The diameter of the portion 126 is such that it can be received snugly within the panel aperture 112, as shown in Fig.2. The bush has a longitudinal cylindrical bore 115 dimensioned so as to be capable of snugly receiving the cylindrical body 116 of the LED 110. The length of the reduced diameter portion 126 is chosen such that, when the bush has been inserted in the aperture with the shoulder 128 in abutment with the underside of the panel, said one end of the bush, carrying the flange 124, projects beyond the upper surface of the panel to such an extent that, when the LED 110 is inserted from below into the cylindrical bore 115 in the bush (as indicated by arrow A in Figs. 1 and 2), the hemispherical lens portion 118 of the LED eventually engages the flange 124 and urges it radially outwardly whereby to distort the part of the bush extending above the panel aperture sufficient to resist withdrawal of the bush from the panel aperture. At the same time, the resulting reactional distortion of the bush 114 acts to grip the outer periphery of the led and thereby prevent its withdrawal from the bush. By this means, therefore, both the bush 114 and LED 110 are held securely in place in the panel aperture. Fig.4 illustrates the latter condition. Figs. 5 to 7 illustrate a more complex version where there is positioned in the bush a separate lens member 130. The principal difference between the two embodiments is that, in the second embodiment, the outward distortion is obtained by the provision of an inwardly directed shoulder 132 disposed at a position spaced from the upwardly projecting end of the bush but just beyond the level of the upper surface of the panel 113. In this case, the radially inwardly extending flange 124 is still provided but is used to retain the lens disc 130 as shown in Figs. 5 and 7. Although in the illustrated embodiments, the flange 124 is shown as being annular and continuous, in other embodiments this flange could be replaced by a plurality of radially inwardly directed fingers spaced around the mouth of the bush 114. As a result of the above described construction, there is provided a means of securely mounting a conventional LED in a panel aperture using a very simple bush and without any need for modification or adaptation of the LED itself.

Claims: A panel/chassis mounting indicator lamp comprising a first part in the form of a bush(114) of resilient material for insertion, in use, lengthwise into an aperture (112) in a panel/chassis (113), the bush (114) having a longitudinal through bore (115) and an outwardly extending shoulder (128) at or adjacent one end for limiting the depth of insertion of the bush into the aperture (112), the outwardly extending shoulder (128) of the bush (114) being formed, so that in use, a portion of the bush will project beyond the aperture (112) on the opposite side of the panel/chassis (113) to that engaged by the shoulder, and a second part in the form of an unmodified LED (110) having a solid plastics body (116) which is received, in use, within the bush bore (115), the outer peripheral surface of the LED body engaging with the bush such as to distort the bush (114) so that it is expanded, on the side of the panel/chassis aperture opposite to that engaged by the shoulder (128) sufficiently to prevent withdrawal of the bush from the chassis aperture (112) and to cause the bush to grip the LED (110) to prevent withdrawal of the LED therefrom, characterised in that there is formed within the bush bore (115) an internal projection (124) which is adapted to be engaged by the hemispherical end (118) of the LED (110) when the latter is inserted into the bush bore (115), whereby to outwardly distort the projecting portion of the bush (114) sufficiently to prevent withdrawal of the bush from the panel/chassis aperture (112). An indicator lamp as claimed in claim 1, wherein the internal projection comprises an annular flange (124) disposed at the end of the bush which projects beyond the panel/chassis aperture (112). An indicator lamp as claimed in claim 1, wherein the internal projection comprises a radially inwardly directed shoulder (132) in the bush bore disposed at a position within said portion which, in use, projects beyond the panel/chassis aperture (112). An indicator lamp as claimed in claim 3, wherein, in addition to said shoulder (132), the bush is formed with an annular flange (134) disposed at the end of the bush which projects beyond the panel/chassis aperture, the flange (134) serving to retain a lens disc (130) within the bush (114) in front of said hemispherical end of the LED (110).

Inventors: ARMISTEAD TREVOR, EDWARDS GEOFFREY STEPHEN, FELLOWES MICHAEL, LOGAN PHILIP MALCOLM, ARMISTEAD, TREVOR, EDWARDS, GEOFFREY STEPHEN, FELLOWES, MICHAEL, LOGAN, PHILIP MALCOLM
Applicants: OXLEY DEV CO LTD, OXLEY DEVELOPMENTS CO., LTD.
Application year: 1991
Main classification: F21Q3
IPC codes: F21S8, F21V19