Multicolor Indicators

Abstract

A multicolor indicator system has two or more lamps with differently colored filter and a housing with a plurality of reflecting facets such that light is reflected out through a viewing aperture from each lamp over the whole of a required range of viewing angles.

Description

This invention relates to multicolor indicators, that is to say, indicators having a colored light display in which indication is given by one or more changes of color. Such displays may be used to indicate any one of two or more states of operation of a machine or process or the like or may be used as an artistic or decorative or testing device.

The use of a color change system is preferable in many cases to a simple on/off arrangement of a single lamp or the like since it avoids the possibility of false and possibly dangerous indication due to one or more lamp failures; for example in a two-color system to indicate by one or other of two states by lighting one or other of two differently colored lamps, the third state with no illumination is an obvious fault indication. Commonly a number of indicating units would be arranged in line or in other form; these units may be identical but this is not essential. A typical example of the use of such indicating apparatus is in the boiler water level indicating apparatus. Such apparatus conveniently has an in-line, vertical display using indicating units arranged vertically in line; each indicating unit provides green illumination if an associated probe is below water level or red if the associated probe is above water level.

For display purposes filament lamps are a convenient form of primary illumination; they may be used in conjunction with color filters for color light displays. The average life of an ordinary filament lamp is only of the order of 1,000 hours but special types have recently become available having average lives of 50 to 100 times this period. Unfortunately these lamps are available only with low power input ratings, typically 300mw. and with a correspondingly low light output. If such low power lamps are to be used for display purposes under conditions of external ambient lighting sufficient for other work such as the control of machines, virtually the whole of their available light output must be distributed as evenly as possible over the whole of the solid angle required to cover all the viewing positions, with as little light as possible being directed outside this angle or otherwise absorbed. Translucent or frosted screens or reflectors introduce absorption and scattering of light and it is therefore desirable that the viewing path must be either transparent or directly reflective throughout. It is commonly desirable that the color, whichever color is to be displayed, should appear across the whole viewing surface of the display unit rather than be restricted to one particular position as otherwise a change in color introduces a shift in the position of the display.

The present invention is concerned more particularly with the construction of an improved form of unit for providing a display of two or more colours.

According to this invention, a color light indicator system comprises at least two lamps providing light of different colors, a housing having a viewing aperture through which can be seen a surface having a plurality of reflecting facets, the facets being arranged to reflect light from the various lamps outwardly through the viewing aperture. This construction enables light from any of the lamps to be reflected outwardly through the viewing aperture in the required directions. Preferably two or more facets are arranged to reflect light from each lamp through the viewing aperture.

The facets may be reflecting surfaces on the inside face of the housing. Conveniently however the facets are facets of a block of transparent material which form internal reflecting surfaces in the block and, in this case, conveniently the block has a flat surface lying in or parallel to said viewing aperture. Thus an observer sees the housing with this flat surface in the viewing aperture, the surface appearing to be illuminated with any of the colors according to which lamp is illuminated; in practice the facets can readily be arranged so that the illumination appears uniform over the whole of the viewing aperture.

For many purposes a two-color indicator system is required and the invention will be more readily understood by describing firstly a two-color system before considering arrangements with more than two colors.

According to one aspect of the invention a color light indicator system having two lamps providing light of different colors comprises a housing having a viewing aperture through which can be seen a surface having a plurality of reflective facets, some of the facets lying in planes passing through one lamp whereby those facets reflect light only from the other lamp and the other facets lying in planes passing through said other lamp so as to reflect light only from said one lamp, and wherein the reflecting facets are arranged to reflect the light from their respective associated lamps outwardly through the viewing aperture.

It will be seen that the form of indicator system described above enables each of the two colors to be reflected so as to pass out in the required direction through the viewing aperture. Usually a plurality of facets would be provided reflecting light from each lamp and, on looking into the viewing aperture, there will appear to be a continuous color display right across the aperture. Since each facet is for the purpose of reflecting light from one light source only, the facet can be angularly disposed to the optimum direction of the reflected light. It is thus possible to reflect substantially all the light into the required viewing angle.

In one convenient form of construction, two lamps are arranged one at each side of the housing with the viewing aperture in the front of the housing between the lamps and the reflecting surface forming the rear wall of the housing. By providing additional reflecting surfaces around each of the lamps, the whole of the light from each lamp may be directed on to the reflecting facets. Conveniently, if the lamps are spaced horizontally, the facets for the two different lamps are arranged alternately in vertical strips on the rear surface of the housing. Because each facet has its plane aligned with one of the lamps, it is not illuminated by that lamp and it does not obstruct illumination of the other facets by that lamp. In the simplest form the facets are flat planes. In some cases however it may be desired to focus the light and for this purpose the facets may have concave surfaces; provided the periphery of the concave surface defines a flat plane passing through one of the lamps, then such a surface receives light only from the other lamp and will not obstruct illumination of facets lighted from the first lamp.

The facets may be equal or unequal in size. In general they will be symmetrically arranged about the centerline of the system. As will be shown later, if the lamps are considered as point sources and the intensity of illumination is constant for equal increments of angle around the point source, then it is preferable that the various facets should subtend equal angles at the point of the light source which they are reflecting.

In any of the arrangements described above, preferably the lamps are so arranged within the housing that they cannot be directly seen through the viewing aperture by an observer and a reflector is associated with each lamp to direct all the illumination from the lamp into the angular region over which the facets for reflecting light from that lamp extend.

Although a two color system has so far been described it is possible to use three or more colors. For example it will be apparent that one could have three lamps, each producing light of a different color, arranged so that they are not in line and have three sets of facets, the facets in each set being arranged with its plane passing through the line joining two lamps so that the facet reflects only light from the third lamp. Thus the three sets of facets are respectively associated with the three lamps, each facet reflecting light from one lamp and the angular positions of the facets can be chosen so as to give the optimum direction for the reflected light. As will be described later, it is possible to have more than three differently colored lamps and the invention includes within its scope a color light indicator system having three or more lamps providing light of different colors, the lamps being arranged in one plane in a housing having a viewing aperture parallel to said plane through which can be seen a surface having a plurality of concentric annular facets lying within a region surrounded by the lamps, each facet extending as a continuous surface one around another and the facets at each point having a slope such that each lamp can be seen through parts of alternate facets.

A lens system may be provided across the viewing aperture.

If the lamps have to have separate color filters, the filters may be arranged as lenses arranged so that the focal point lies at the light source. If filters are employed, further color changes may be incorporated by changing the filters, mechanically or electrically operated means being provided for this purpose.

In the following description, a number of embodiments of the invention will be described, reference being made to the accompanying drawings in which:

FIG. 1 is a diagram showing a two color indicator in transverse section;

FIGS. 2 and 3 are diagrams illustrating the effect of putting reflecting facets at the wrong angle;

FIGS. 4 and 5 are diagrams illustrating modifications of the construction of FIG. 1;

FIG. 6 is a diagram for explaining how the angular extent of the surface of each facet is determined;

FIG. 7 is a transverse section of an indicator showing facets arranged to give an indication over a predetermined viewing angle and assuming that the lamp sources give uniform illumination;

FIG. 8 is a plan view of a module using a facet of the type illustrated in FIG. 7;

FIG. 9 is a plan view of a module for use with six different colors;

FIG. 10 is a section along the line 10-10 of FIG. 9;

FIG. 11 is a diagram illustrating how the modules of FIGS. 9 and 10 are stacked together;

FIG. 12 is a plan view of a four lamp module;

FIG. 13 is a section along the line 13-13 of FIG. 12;

FIG. 14 is a plan view of another four lamp module;

FIG. 15 is a section along the line 15-15 of FIG. 14; and

FIG. 16 is a diagram illustrating how modules such as those of FIGS. 14 and 15 may be stacked together.

FIG. 1 is a diagram showing a housing 10 containing two lamps 11, 12 of different colors. In the front of the housing is a viewing aperture 13. The rear surface of the housing contains, in this particular example, eight reflecting facets numbered 1 to 8. These facets are flat reflecting surfaces extending from top to bottom of the housing and it will be seen that facets 1, 3, 5, 7 lie in radial planes passing through the lamp 11. Thus no light from the lamp 11 can fall on these facets and be reflected thereby. Similarly the facets 2, 4, 6 and 8 lie in radial planes through the lamp 12 so that no light from the lamp 12 can fall on these facets and they reflect light only from the lamp 11. It will be apparent that if one considers any one radial plane through a lamp such as for example a plane containing the facet number 1, a facet at any particular position on this plane will reflect light from the lamp 12 in a predetermined direction. The positions of the facets in the various planes are chosen so that the light from the lamps is reflected forwardly through the viewing aperture. It will be seen that if one, for example, considers the lamp 11 with light being emitted therefrom over an angle which extends in a clockwise direction from the plane of facet 1 to the right-hand end of facet 8, all this light falls on the four facets 2, 4, 6 and 8. All this light is therefore reflected forwardly through the viewing aperture.

As stated above, the facets lie in radial planes planes. This is not essential but with some dispositions, light may be lost through not being reflected out through the viewing aperture. Referring for example to FIG. 2 there are shown facets 3 and 4 together with a part of facet 2 in a construction in which the radial plane from the lamp 11 extends along the dashed line 20. It will be seen immediately that the facet 3 together with part of the facet 2 shields part of the facet 4 which is thereby not utilized. However no light is lost with the arrangement of FIG. 2. FIG. 3, on the other hand, illustrates a similar construction in which the facet 3 is sloping at the opposite direction to the radial plane indicated by the line 20. In this case part of the light from the lamp 11 falls on the facet 3 and is thereby wasted compared with the arrangement of FIG. 1 in which it all falls on facets 2, 4, 6 and 8.

Reflectors 22, 23 in FIG. 1 are provided around the lamps to confine the radiation to the required solid angle in which the appropriate facets are illuminated.

In FIG. 1 all the facets are made of the same size. This is not essential and FIGS. 4 and 5 illustrate constructions in which facets of different size are employed. The reflecting facets are shown at 25 in FIG. 4 and 26 in FIG. 5.

FIG. 6 is an explanatory diagram for explaining how the optimum conditions of viewing angle and intensity within that angle can be determined. Under normal conditions, the viewing angle will be symmetrically disposed about the perpendicular to the plane of the viewing aperture and it is desirable that the intensity of light throughout that angle should be constant for both lamps.

On the assumptions that the lamps may be considered as point sources and that the intensity of illumination is constant for equal increments of angle around the point source, the use of plane reflecting surfaces results in the external viewing angle, ignoring change of refractive indices between media, being the same as the total angle subtended at the source by the reflector array, and thus even illumination may be achieved if all reflectors subtend equal angles at the source. The angle between the plane of the lamps and the nearest reflecting surface determines the angle of the centerline of the viewing angle when taken in conjunction with the number of reflecting surfaces per lamp. It can be shown that, where:

n= total number of equal increments of angle per lamp (i.e. total number of reflectors per lamp);

a= starting angle for reflection;

b value of each increment of angle;

x = value of maximum required viewing angle from the perpendicular to the plane of the lamps.

These parameters are illustrated in FIG. 6 which shows two lamps 30, 31 and facet 1 indicated at 32 and facet n indicated at 33.

It will be seen that:

nb = 2x

and 90.degree. - 3a - (n - 1)b = -x

One possible solution for these equations is shown in FIG. 7 where n = 5, a = 4.degree., b = 12.degree. and x = .+-. 30.degree.. This construction gives the following coverage from each reflecting facet:

facet 1 - 30 .degree. to - 18 .degree.

facet 2 - 18 .degree. to - 6 .degree.

facet 3 - 6 .degree. to + 6 .degree.

facet 4 + 6 .degree. to + 18 .degree.

facet 5 + 18 .degree. to + 30 .degree.

In FIG. 7 the two lamps are shown at 40, 41 with reflectors 42, 43 for confining the radiation to the required angular region in which the facets to be illuminated lie. The dashed line 45 shows the position at which the viewing aperture would have minimum width for viewing over the required angular extent. In practice however, to reduce the depth of the indicator from front to back, a slightly wider viewing aperture would usually be preferred such as that indicated at the line 46.

It will be immediately apparent that indicators such as are shown in FIGS. 1, 4, 5 and 7 having parallel top and bottom faces of the housing may be stacked one above another to give a column of color light indications. In such an assembly, it is not necessary however that all the indicators should be identical.

FIG. 8 illustrates a practical form of construction for a module shaped along the lines explained with reference to FIG. 7. Referring to FIG. 8 the module has a transparent body 50 (conveniently a transparent plastics material such as polymethyl methacrylate material) with facets such as are shown at 51, 52. Two blocks 53, 54 of differently colored transparent plastics material, typically polycarbonate mouldings, are secured on opposite sides of the main block 50 using a transparent cement. These blocks 53, 54 form housings for lamps, one of which is shown at 55, which are connected as indicated at 56 to connecting pins 57. For clarity in the drawing, the lamp and connecting pins have been shown only in the block 53. In the block 54 there is shown only a heat sink and reflector system for the lamp; such a heat sink and reflector would be provided for each lamp. This heat sink and reflector comprises a part cylinder 58 with an internal reflecting surface which extends around the lamp in an aperture in the block 54 so as to reflect all the light into the main block 50. This part cylinder 58 has an extension 59 lying outside the block and forming a heat sink. The particular unit shown in FIG. 8 forms a module; a number of such modules are separately plugged into a housing (not shown) having connecting sockets for the lamps and finger grips 61 are formed on the side surfaces of the module near the front thereof to assist extraction. The housing would provide an opaque surface for the block 50 so that reflections occur from the facets 51, 52. It is preferred, however, to metallize the block over its whole outer surface except for the viewing aperture, reflections thus occurring at the metallized surfaces. The reflecting facets are positioned as previously described with reference to FIGS. 1 to 6.

It will be apparent that three-color system can also be employed. Typically the three lamps of different color would be arranged symmetrically at the apices of an equilateral triangle within the housing. Considering a three-color modification of the system of FIG. 1, two lamps might be arranged in a vertical plane (that is to say a plane normal to the plane of the paper) through the position of the lamp 11 so that the facets 1, 3, 5 and 7 each reflect light only from the lamp 12. Then in place of the facets 2, 4, 6 and 8 there would have to be two sets of facets, the facets in one set being in planes which pass through the lamp 12 and one of the other lamps and the facets in the other set being in planes to pass through the lamp 12 and the second of the other lamps. Alternatively, the facets may be circular facets similar to those described below with reference to FIGS. 9 to 11.

FIGS. 9, 10 and 11 illustrate an arrangement for displaying six different colors. The six lamps are arranged at positions spaced evenly around a center point of a block 70 of transparent plastics material. The various lamps are put in apertures 71 each in a separate block 72 of transparent plastics material of a different color, the various blocks 72 being shaped so that together they form a hexagon externally whilst their inner surfaces form a circular frustum of a cone which is cemented with optical cement in a recess around the periphery of the block 70 which has a hexagonal base. The central block 70 thus abuts against these color blocks 72 and, as is most clearly shown in FIGS. 9 and 10, has a series of concentric annular facets 73, 74, 75 and 76. Each facet is of conical form, the various facets sloping in alternate directions so that in a diametral plane through any lamp alternate facets have a slope such that the plane of the facet passes through the center of the lamp filament. The combined assembly of the blocks 70 and the block 72 is metallized over its whole surface except for a flat viewing surface 77 opposite the concentric facets 73 --76 and for the lamp apertures. The various hexagonal units, each constituted by a block 70 with its associated blocks 72, may be assembled together as shown in FIG. 11 to form a surface in which each of the different modules 78 may be made to appear any one of six colors by appropriate switching of the various lamps for the modules.

FIGS. 12 and 13 illustrate an arrangement which is generally similar in principle to that of FIGS. 9 to 11 but which makes use of four lamps. In the constructions of FIGS. 12 and 13 there is a central element of transparent plastics material 80 having the concentric annular conical facets 81 on its top surface. The element is completed around two circular arcs by means of four shaped blocks 82 to 85 formed of different colored transparent plastics material each of which has a recess 86 to accommodate a lamp. As in the arrangement of FIGS. 9 to 11, the combined assembly of central element 80 and the blocks 82 to 85 is metallized over all its surfaces except for a viewing face 87 opposite the facets 81 and the lamp apertures 86. The rectangular elements of FIGS. 12 and 13 may be assembled together to form a surface display similar to that of FIG. 11.

FIGS. 14 and 15 illustrate a modification of the construction of FIGS. 12 and 13 in which a four lamp module is of trapezium shape. This is formed as before of a central transparent block 90 with concentric annular facets 91 and with four colored transparent blocks 92 to 95 each having a bore 96 to hold a lamp. The assembly is metallized all over except for a viewing face 97 and the lamp apertures. In the particular arrangement shown in FIGS. 14 and 15, the module is of trapezium form so that a number of similar modules 98 can be arranged together, as shown in FIG. 16, to form line type display.

The constructions of FIGS. 9 to 15 may be used for multicolor indicators for many different purposes. They may for example be used as display devices for power station control rooms or for railway marshalling yards and for centralized traffic control centers in cities. In the latter case for example degrees of traffic density or direction of flow may be presented as different colors on a mimic diagram in the form of a map. In teaching or exhibition work, these devices may be used to form animated diagrams showing related quantities, for example showing discrete steps throughout an apparatus or process. More generally, in display panels, for example on aircraft, where the saving of space is required, these modules permit the use of color variety at a point to obviate the need of having several different on/off displays in close proximity. These modules may also be used for decorative purposes. The viewing faces of the modules may be engraved or otherwise marked for identification or decoration. Constructions with four or more lamps may also be used as a two-color display, two or more lamps being employed for each color to give greater reliability than constructions using only a single lamp for each color.

The constructions of FIGS. 9 to 15 make use of annular concentric reflective facets as these are the most convenient for manufacture. However it is possible to use noncircular shapes, e.g. elliptical or other curvilinear forms. In some cases it may be convenient to use square shaped blocks having straight facets, each facet extending parallel to a side of block between two diagonals so that in effect, a square set of facets, one inside another, is provided instead of circular facets. Although FIGS. 9 to 15 illustrate arrangements having four or more lamps, similar constructions may be used for three lamps; the blocks in this case are conveniently of triangular form with the lamps in inserts at the apices of the triangles. The facets are preferably circular for convenience of manufacture but can be of other shapes.

Claims

I claim:

1. A color light indicator system comprising at least two lamps providing light of different colors, a reflector block of transparent material, said block being shaped to have a number of facets forming internal reflecting surfaces, said facets including at least first and second sets of reflecting facets, two transparent lamp housing blocks, each lamp housing block having a recess in which one of said lamps is housed, said lamp housing blocks being secured on opposite sides of said reflector block and each having a surface abutting a surface of said reflector block so that light from said lamps is transmitted into said reflector block, the two lamps and lamp housing blocks being arranged to provide light of different colors, each lamp housing block, further including a metallic reflector reflecting light from the lamp into the reflector block said reflectors extending outwardly of the lamp housing block to form two parallel pins constituting heat sinks, electrical connector pins for the two lamps extending outwardly of the lamp housing blocks parallel to said heat sinks, said reflector blocks further having a viewing face normal to the direction of said pins, each facet of said reflector block having its boundary defining a flat plane and its reflecting surface lying in or behind the flat plane, the facets of said first set having the planes defined by their boundaries lying each in a different radial plane extending from one of said lamps, and the facets of the second set having the planes defined by their boundaries lying each in a different radial plane extending from another of said lamps, the planes of the facets of the first set being angularly disposed to reflect light from said another of said lamps through said viewing face and the planes of the facets of the second set being angularly disposed to reflect light from said one of said lamps through said viewing face.

2. A color light indicator system as claimed in claim 1 wherein said lamp housing blocks are transparent blocks of different color to transmit light of different color into said reflector block.

3. A color light indicator system as claimed in claim 1 wherein the facets are arranged symmetrically about the centerline of the system.

4. A color light indicator system as claimed in claim 1 wherein the two lamps are spaced horizontally and the facets for the two different lamps are vertical strips arranged alternately on the rear surface of the reflector block.

5. A color light indicator system as claimed in claim 1 wherein the facets are flat planes.

6. A color light indicator system as claimed in claim 1 wherein the various facets are arranged to subtend equal angles at the point of the light source which they are reflecting.