GB2182802A - L.E.D. indicator device - Google Patents

Abstract

The device comprises a plurality of light emitting diodes (10A, 10B) electrically connected for simultaneous energisation and disposed on a small printed circuit board (20) in a particular spatial arrangement relative to a common diffusing cover (38) to give a desired even light effect. The device has pins (14A, 14B) by which it can be mounted onto another printed circuit board etc. There may be two interspersed sets of light emitting diodes of different colours also allowing a third colour at part energisation. <IMAGE>

Description

SPECIFICATION Light indicator devices DESCRIPTION This invention relates to light indicator devices and has arisen in connection with the use of light emitting diodes (LEDs).

In our experience as specialists in relation to indicator devices using LEDs, it is not easy to get uniform or other desired illumination intensities, whether actual or as perceived, and especially relative to different sizes and/or effective colours of LEDs. Thus, LEDs are generally considered to be of low light intensity and the tendency is for LEDs as such to be provided with an optimised light output, i.e. leaving it to the manufacturers of devices using LEDs to take such steps as they can or wish to make effective adjustment of such output, albeit that efficiency and effectiveness of LEDs usually require them to be driven for the aforesaid optimised light output.Also, the availability of LEDs in ever decreasing sizes and costs, whilst good for matching to general progress in miniaturisation of solid-state electronics, has, if anything, a tendency to emphasise the different actual and/or perceived intensities of very small LEDs.

It is an object of this invention to facilitate the use of LEDs, particularly if not exclusively the smallest and/or cheapest LEDs, in what might be termed more "user-friendly" ways, and further by way of assisting in dealing with the aforesaid difficulties.

To that end, we have developed a combination of plural simultaneously energised LEDs organised in a spatial arrangement related to location of or for a common translucent, opalescent or otherwise diffusing light-transmitting cover, as can be conveniently achieved using a suitable small printed circuit board (pcb) in a container closed by such a cover.

In preferred embodiments, such covers can take any desired shape, i.e. to suit the user's requirements and may even be applied by the user, and the plural LEDs can be connected serially by conductive tracks of the pcb; say extending between terminal holes for consecutive ones of the LEDs. Then, we find it possible to provide satisfyingly even but highly visible illumination, effectively as back-lighting resulting in infusion of the cover with light from the associated plural LEDs at appropriate spacings and positions.

A particularly preferred generally circular light indicator results from LEDs spaced symmetrically, say substantially equally both radially and angularly and/or centrally on a circular pcb fitting into a substantially circular cylindrical hollow housing also accepting or taking a substantially circular said diffusing cover. For a small such indicator device, say of about 17 mm diameter, three or four such LEDs are generally found to be satisfactory, but more could be used at the same radial positions, or at further radial spacings, if desired, whether for greater size or for greater intensity.

It will be appreciated that it is thus possible to make substantial contribution towards achieving uniformity of actual or perceived intensityby varying the number and/or dispositions of LEDs for given diffusing covers, whether according to the size of such covers or according to inherent intensities associated with the colour of LEDs used.

Moreover, according to a particular aspect of this invention, two sets of plural LEDs of two different colours, respectively, can be used in a single indicator device to give corresponding options of illumination colours according to which set of LEDs is energised. For appropriate colours, a third optional colour of device illumination can be achieved by simultaneous energisation of both sets.

For a substantially circular pcb, say small as above, one set of LEDs of greater inherent intensity than the other may comprise three LEDs substantially at apices of an equilateral triangle, and the other set may comprise four LEDs of which three are also substantially at apices of another equilateral triangle, say canted relative to the first so that respective apices interleave, and the fourth substantially central. It will be evident that such arrangements can be effectively expanded or varied to other numbers and dispositions, for example four in one set disposed at corners of a square and five in the other of which one is central and four are also dispaced at corners of a square interleaving the first square.

It is, of course, not essential to this invention that pcbs and/or housings be substantially circular though it is generally preferred that they correspond reasonably closely in shape. Then, an assembled pcb, with appropriate connection pins attached and extending away therefrom, can conveniently rest inset in the housing on a ledge thereof, say potted therein to its rearside and the translucent or otherwise diffusing cover fixed into or over said inset above the tops of the LEDs, preferably finishing with the exterior of the cover and the potting substantially flush with or flushing off ends of the housing. Such a device is readily plugged into another pcb or a suitable socket and/or located in a suitable hole in a panel or otherwise relative to a panel whether flush, proud or inset and with or without a diffusing cover.

Specific implementation of this invention will now be described, by way of example, with reference to the accompanying drawing, in which: Figure 1 is a section through one light indicator device; Figure 2 is a top end view with cover removed; Figure 3 is a bottom view of the pcb only; Figures 4A and 4B show end and side views of an individual LED; Figure 5 is a circuit diagram relevant to the embodiment of Figs. 1 to 4; Figure 6 is a top end view of a second embodiment having two sets of LEDs; Figure 7 is a corresponding bottom view; Figure 8 is a bottom view of the pcb only; and Figure 9 is a circuit diagram relevant to the embodiment of Figs. 6 to 8.

In the drawings, referring first to Figs. 1 to 5, a plurality of LEDs 10A-10D are connected in series with a feed resistor 12 between pins 14A, 14B for relatively positive and negative supply voltages, i.e. for simultaneous energisation when such voltages are applied, see switch 16 indicated only symbolically in Fig. 5 between sockets or the like 18A, 18B for the pins 14A, 14B, which sockets may be holes in a pcb of equipment with which the illustrated indication device is to be associated.

The LEDs 10A-10D are shown mounted to a small pcb 20 by way of their terminal tags 10X, 10Y bent back towards their bodies 10Z and pushed through pairs of holes 22A-22D, 24A-24D in the board and thereby into electrical connection with conductive tracks 26 on the other side or rear of the pcb, conveniently assisted or consolidated by soldering up (not shown) to such tracks 26. It will be appreciated that the conductive tracks 26 are suitably disposed to enable achievement of a series circuit from the positive pin 14A electrically connected in hole 28A thence via track 26A to hole 22E for the resistor 12 and through the latter to hole 24E and track 26B to hole 22A for LED 10A, further via hole 24A, track 26C and hole 22B to LED 10B, and so on to track 26F via hole 24D to the negative pin 14B in the hole 28B.

The pcb 20 is shown as circular, and the LEDs lOA-lOD are shown symmetrically arranged radially and angularly, actually substantially at corners of a square at about 60% to 75% of the pcb radius.

A housing 30 for the illustrated device comprises a hollow bush member internally stepped at 32 to seat the pcb 20 medially thereof and with space from its entry end for potting up to the underside of the pcb, see 34. Before such potting, it is convenient to affix a partial sleeving 36 to the relatively positive pin 14A, which sleeving can be shrunk onto the pin 14A and is preferably colour-coded to indicate the colour of the LEDs 10. The other end of the housing is shown with a cover 38, actually going clear across rather than inset, and is so affixable by cement or adhesive. An annular adhesive pad can be used as an aid to mount the device of Figs. 1 to 4.

Turning to Figs. 6 to 9, a first set of LEDs 40A-40C are associated with a pcb 42, relatively positive and negative pins 44A, 44B, resistor 46 and conductive tracks 48A-48E, i.e. in a series circuit for simultaneous energisation. Three such LEDs 40 are shown in a circular pcb 42 in symmetrical arrangement substantially at apices of an equilateral triangle. Another set of LEDs 50A-50D are associated with the same pcb 42, relatively positive and negative pins 54A, 54B, resistor 56 and conductive tracks 58A-58G plus wire link 58W, i.e. in a series circuit for simultaneous energisation. Four such LEDs 50 are shown on circuit pcb 42 in symmetrical arrangement with LED 50A central and LEDs 50B-50D substantially at apices of an equilateral triangle canted relative to that for LEDs 40 so the LEDs 50B-50D interleave with those 40A-40C, but with the former somewhat more spaced along radii.

The positive pins 44A and 58A will be colour coded via sleeves 60A, 60B to correspond with the colours of LEDs 40 and 50, respectively. Energisation via either of pins sets 44 and 58 will thus give different colours, say red and green, that for LEDs 50 (say green) being assumed to have less effect in normal energisation conditions, at least as perceived, thereby to assure more consistent brightness as between such lighting colours.

For appropriate colours, simultaneous energisation of the LED sets 40 and 50 can give a third colour, say yellow for red and green, all according to the requirements of circuitry with which the device of Figs. 6 to 8 is to be associated.

Claims (18)

1. A light indicator device comprising a plurality of light emitting diodes electrically connected for simultaneous energisation and disposed in a particular spatial arrangement relative to a location of or for a common diffusing cover.

2. A light indicator device according to claim 1, comprising a printed circuit board carrying similar said light enabling diodes and their electrical connection to each other and to terminals for electrical supply to the light emitting diodes.

3. A light indicator device according to claim 2, wherein the printed circuit board has conductive tracks between mounting holes for the light emitting diodes and serially connecting same.

4. A light indicator device according to claim 2 or claim 3, wherein the printed circuit board carries pins as said terminals which pins extend from an opposite side of the printed circuit board to that at which the light emitting diodes face said cover location.

5. A light indicator device according to claim 4, wherein a resistor in series with the light emitting diodes is at said opposite side of the printed circuit board.

6. A light indicator device according to claim 4 or claim 5, wherein the printed circuit board is located against internal edging of a generally cylindrical container one end of which affords said cover location and beyond the other end of which said pins protrude.

7. A light indicator device according to claim 6, wherein said printed circuit board is potted into said container from said other end.

8. A light indicator device according to any one of claims 4 to 7, wherein at least one of said pins has a sleeve extending along part of its length and coloured to indicate the colour of the light emitting diodes.

9. A light indicator device according to any preceding claim, wherein the spatial arrangement affords regularity of spacing of the light emitting diodes in relation to said cover so as to give a substantially even diffusion of light thereby.

10. A light indicator device according to claim 9, wherein one of the light emitting diodes is disposed centrally of others of the light emitting diodes.

11. A light indicator device according to claim 9 or claim 10, wherein, for a substantially circular said cover, the light emitting diodes are disposed or also disposed at positions spaced substantially equally both radially and angularly.

12. A light indicator device according to any preceding claim, comprising two sets of plural light emitting diodes those of each set being all the same columns but such colour being different for each set.

13. A light indicator device according to claim 12 with claim 8, wherein at least one supply pin for each set has a said sleeve.

14. A light indicator device according to claim 12 or claim 13, wherein the spatial arrangements of the light emitting diodes of the two sets are interspersed with each other.

15. A light indicator device according to claim 12, 13 or 14, wherein the two sets are energisable separately or together to give three possible colour.

16. A light indicator device according to any one of claims 12 to 15, wherein the light emitting diodes of one said set are of greater inherent light intensity than the light emitting diodes of the other set and are fewer in number.

17. A light indicator device according to claim 16,,wherein the light emitting diodes of said one set are three disposed at apices of an equilateral triangle and the light emitting diodes of said other set are four of which one is control and the others are at apices of an equilateral triangle and offset relative to the light emitting diodes of the one set.

18. A light indicator device substantially as herein described with reference to and as shown in the accompanying drawings.