GB2185576A - Instrument pointer assembly - Google Patents

Abstract

An instrument pointer assembly comprises a light conductive boss member 23 attached to a spindle 22 for rotation about an axis and a light conductive needle member 24 comprising a pointer portion 32 and a co-extensive root portion 31 attached to said boss member 23 so that the needle member 24 extends radially at right angles to said axis with the root portion 31 intersecting said axis, said boss member 23 having first and second spaced and parallel reflecting surfaces 25, 27 at 45 DEG to said axis whereby light travelling parallel to said axis and incident upon said surfaces is reflected within the boss member at right angles to said axis and in a direction opposite to that in which said pointer portion 32 extends. A 90 DEG prism 28 deflects said light reflected from said first and second surfaces 25, 27 along the length of said needle member 24 from the end of the root portion which is remote from the pointer portion so that said light can illuminate the whole of the lower face of the needle member 24 including that region of the lower face defined by the root portion 31,which region intersects said axis. The pointer is mounted to extend through a light conducting sheet provided with an opaque apertured surface to provide indicia. A plurality of light sources secured below the sheet in saddles illuminate the inside of the sheet via 45 DEG facets provided in the outer surface of the sheet. Light from two or more light sources is directed through the sheets towards a hole in the sheet through which the spindle extends 45 DEG facets, parallel to facets associated with the saddles diverting the light parallel to the spindle to the pointer assembly. <IMAGE>

Description

SPECIFICATION Instrument pointer assembly This invention relatesto an instrument pointer assembly principally but not exclusively for use in a road vehicle instrument such as a speedometer and to an instrument using the pointer assembly.

A known pointer assembly comprises a light conductive needle integral with and extending radially outwardlyfrom a boss whereby the pointer assembly is attached to a spindle. The needle, at its boss end, has a 45" reflecting surface which receives light reflected upwardly, parallel to the spindle axis, from a light conductive sheet forming part of the instrument and which reflects this light lengthwise of the needle. The upper and lower faces of the needle are polished and the lowerface is painted sothatthe needle, by virtue of internal reflection from the painted lower face appears as an illuminated barofthe colour of the paint coating the lowerface.It will be recognisedthatthelowerfaceofthe needleter- minates at the periphery of the boss and so the perceived illuminated bar of colour can extend only to a point adjacent but spaced from the axis of rotation of assembly.

Currentstyling requirements dictate that the perceived illuminated barofcolourshall extend through and beyond the axis of rotation and a prior attemptto achieve this is disclosed in West German PatentApplication No. 3201571 wherein a one piece needle receives light passing adjacent one side of the spindle andturnsthe lightfirstthrough 900 and then through 1800 so that the iighttravels the length ofthe needle.

However, the arrangement illustrated in West Ger- man Patent Application No. 3201 571 may proveto be disadvantageous in that by virtue of a restricted light collection area, the intensity of illumination of the needle may be inadequate, and it is an object of the present invention to provide a pointer assembly wherein this disadvantage is obviated.

In accordance with the present invention there is provided a pointer assembly comprising a light con- ductive member whereby the pointer assembly can be attached to a spindiefor rotation aboutan axis and a light conductive needle membercompris- ing a root portion and a co-extensive pointer portion, said root portion being attached to said boss member so that the needle member extends at right angles to said axis with the root portion intersecting said axis and the pointer portion extending radially outwardly from the axis, said boss member having first and second spaced and parallel reflecting surfaces at 45" to said axis whereby light travelling parallel to said axis and incident upon said surfaces is reflected within the boss member at right angles to said axis and in a direction opposite to that in which said pointer portion of said needle member extends relative to said axis, the assemblyfurther including 90" prism means for deflecting said light reflected from said first and second surfaces and conducted within the boss member, along the length of said needle member from the end ofthe root portion which is remote from the pointer portion so that said light can illuminatethewhole ofthe lowerface ofthe needle member including that region ofthe lower face defined bythe root portion, which region intersects said axis.

Preferably said first and second surfaces are positioned at opposite sides respectively of said axis such that light reflected from one of said first and second surfaces intersects said axis en route to said prism means.

Desirably said boss member has therein a blind bore for receiving said spindle and said one of said first and second surfaces reflects light in a region of the boss member lying beyond the closed end of said bore.

Preferably said boss member and said needle member are separately formed members, the needle member being attached to the boss member in use buy a cover engaging both members.

Conveniently said prism means is defined by respective 45" reflecting surfaces on the boss member and the root portion of the needle member said surfaces subtending 90 between them.

Alternatively said prism means is integral with one of boss member and said needle member.

In the accompanying drawings; Figure 1 illustrates a light conductive sheet for use in an instrument assembly in accordance with a first example of the present invention, Figure2 illustrates oneform of light collector associated with the sheet of Figure 1, Figure 3 is a sectional view on the lines 3-3 in Figure 2, Figure4isaviewsimilarto Figure 3 of a modification, Figure5isviewsimilarto Figure 2 of a modification, it being noted that Figures 2,3,4 and 5 are shown to an enlarged scale by comparison with Figure 1, Figure 6 is a simplified, diagrammatic representation of part of the light conductive sheet of Figure 1, Figure 7 is an exploded, side elevation view illustrating a pointer assembly for use in the instrument, Figure8isaviewsimilarto Figure7showingthe parts in their assembled condition, Figure 9 is a view similar to Figure 7 ofthe modification, Figure 10 is a view similarto Figure 9 showing the parts assembled, and Figure 11 is a sectional view on the line 11-11 of Figure 10.

Referring to the drawings, there is provided an instrument assembly comprising a housing (not shown) supporting bulb holders, and a printed circuit arrangement for making electrical connections to the bulb holders, the housing being closed at one face by a planar sheet 11 of clear arcylic material. In the example illustrated in the drawings the instrument assembly comprises at least six instruments each performing a different function, but sharing a common housing and sheet 11. It is to be understood however that each instrument could, if desired, have an individual housing and a individual sheet 11.

Figure 1 shows the sheet 11 from below, that isto say from the face presented towards the light sources. Each ofthe instruments includes a movement housed within the housing and including a spindle 22 (Figure 7) which extends upwardly through a respective aperture 12 in the sheet 11.

Overlying the outer face ofthe sheet 11 is an opaque maskwhich is formed with a circular or partcircular aperture, ortransparent region, concentric with each ofthe apertures 12, but of larger diameter, and con- centric with each of the apertures the mask is formed with a row of indica defining the scale ofthe respective instrument.

Extending downwardly from the inwardly presented face of the sheet 11 is a plurality of saddles 13.

Some ofthe saddles 13 are of the form shown in the Figure 2, and some are ofthe form shown at 13a in Figure 5. Each saddle 13 is in the form of a clear arcylic block having a U-shaped slot 14within which the envelope of a bulb defining a light source is received. Above each saddle 13 and aligned therewith the outer face of the sheet 11 is formed with a groove 15 of V-shaped cross-section the walls of the groove 15 being at 450 to the upper and lower faces, and therefore to the thickness, ofthe sheet. Light conducted upwardly, lengthwise within the saddles 13 strikes the faces ofthe groove 15 and is reflected parallel to the sheet 11 within the material of the sheet.

Where saddles 13 are provided at an edge ofthe sheet then the edge region of the sheet immediately above the saddle 13 will be chamfered at 45" to pro- duce a single reflecting surface 15a which is of course equivalent to half of the groove 15. The form of saddle 1 3a which is shown in Figure 5 may be used where space does not permitthe use of a full saddle 13 ofthe kind shown in Figure 2. It will be recognised that the bulbs are supported in bulb holders which in turn are carried by the housing, and the saddles on the sheet are located in accordance with the positioning ofthe bulb holders in the housing. Thus when the sheet is placed in position on the housing the bulbs ofthe bulb holders locate within the saddles so that light from the bulbs is directed upwardly through the saddles, and then laterally within the plane ofthe sheet 11.Light is conducted within the sheet 11 by internal reflection as well as by direct conduction, and there is therefore inevitably scattering of light and consequent upward "leakage" oflightthrough the upperface ofthe sheet 11. It will be recognised therefore that lightwill issue upwardlythrough the apertures or clear regions ofthe overlying mask which definethe indicia ofthe instruments so that the indicia appear as illuminated regions on a dark background. Naturally the mask could be provided with transparent regions which are coloured so that the indicia appear as appropriately coloured illuminated regions.

The "leakage" oflightfrom the uppersurface of the sheet 11 is not sufficient to provide good illumination of the pointer assembly of each instrument.

Generallythe point assembly will include a light con- ductive needle a lower face of which is painted with a light reflective paint, and the intention is that light will enterthe needle adjacentthe supporting spindle ofthe pointer assembly, and will be conducted along the length ofthe needle and reflected from the painted lower surface of the needle so thatthe needle appears as an illuminated bar of colour. In orderto achieve a good intensity of illumination of the needle it is necessary to provide specific meansfordiverting light from within the sheet 11 to the pointer assembly.

In the arrangement illustrated in Figure 1 light is diverted from the sheet 11 to illuminate the pointer assembly of each of the instruments by means of a plurality of 45" reflecting facets. The arrangement is basically similar for each of the instruments, and so only one will be described.

At the region of the sheet 11 where the spindle of an instrument movement is to pass through the sheet the lower face of the sheet is recessed in a mannerto provide a set of three facets associated with each adjacent region of the sheet where light entersthe sheet. For each of the apertures 12 ofthe sheet 11 shown in Figure 1 there are two associated regions where light will enter the sheet. Using for example the aperture 12 which is atthe lower right hand corner ofthe sheet 11 (in Figure 1 ) there is a saddle 13 below the body of the sheet 11 to the left of, and slightiy above the position ofthe aperture 12, and there is a second saddle 13 at the edge of the sheettothe right, and belowtheaperture 12.Thus associated with the aperture 12 is a first set offacets 16 presented towardsthefirst mentioned saddle 13 and a second setoffacets 17 presented towards the other saddle 13. The first mentioned saddle 13 has a V-shaped groove 15 associated with it and one face of the V-shaped groove 15 thus directs light from the saddle 13 towards the facet 16. The other saddle, being at an edge ofthe sheet, has only a chamfered edge surface 1 5a which reflects light from the saddle towards the facets 17, The actual geometry of the facets will be determined bythe relationship between the position ofthe aperture 12 and the posi tion and number of associated light entry points (saddles).Each light entry point can be considered as a linear source within the sheet, and desirably each aperture 12 will be associated with a pair of linear sources. Ideally the two linear sources of each aperture 12will be parallel to one another, and a line intersecting the mid-points of the two sources will pass through the aperture 12. Unfortunately,this ideal orientation will frequently be precluded by other constraints imposed upon the construction of the instrument assembly. In fact, in the sheet illustrated in Figure 1 the ideal orientation does not apply to anyofthe apertures 12, but the actual orientation is arranged to be as close as possible to the ideal.The greaterthe divergence of the aperture 12 from the line joining the mid-points ofthe associated sources, then the more liekly is it that a third linear source will need to be associated with the aperture 12 in orderto achieve even illumination. Of course if third source is associated with an aperture 12 then the aperture 12 will need to have a corresponding third set offacets.

Figure 6 illustrates diagrammatically howthe facets are arranged in an ideal orientation. The upper surface ofthe sheet is denoted by the reference numeral 11 a and the lower face of the sheet 11 is denoted by the reference numeral 1 Each set of facets includes three facets denoted by the suffixes a, b, and c respectively and the planes of each of the facets of a set of facets are parallel.The facets a and c of each set are co-planar and the facet b of each set (the cen terfacet) is parallel to, but offset from the common plane of the facets a and c so thatthe two facets 1 6a, 176 define between them a rectangular gap constituting the aperture 12 through which the spindle of the pointer assembly movement passes.The edges defined where the facets 17 intercept the lower face 1 1b ofthesheet 11 are all parallel to the edge defined by the interception ofthe edge surface 1 5a and the lower surface 1 1b so that each of the facets 17a, 17b, 17cis presented directly towards the linear light source defined by the edge surface 15a. Moreover, each of the facets extends at an angular of 45"to the upper and lower faces ofthe sheet 11 so that light reflected from the surface 15a within the sheet 11 and incident upon the facets 17 is reflected at 90 by the facets 17 and passes upwardly out of the face 11 a of sheet.In an arrangement having ideal orientation the facets 16 are a mirror image ofthefacets 17 and operate in exactly the same manner in relation to their linear light source. The depth ofthe recesses defining the facets 16a, 17a and 16c, 16c,17c is equal to the thickness ofthe sheet 11 so that the facets extend across the whole cross-section of the sheet 11.

It must be recognised howeverthatwhereas in the ideal orientation the set of facets 16 extends parallel to the set 17 this is notthe case where the orientation is other than ideal since it is necessary for the facets of each setto be presented directlytowardstheirrespective linear light source. Thus in the various nonideal orientations illustrated in Figure 1 the general direction of extent ofthe facets 16, within the plane of the sheet 11, diverges from the general extent ofthe facets 17 and the actual geometry of the facets in re lationtooneanotherwill be determined bytheactual orientation of spindle position and saddle position which must be accommodated.

It will be recognised therefore that in practice each ofthe facets will reflect substantially the same amount of light from its respective light source, and thus there will be an even intensityofillumination on both sides of the aperture 12. The mask, in the region of each aperture 1 2 will have a circular aperture through which a substantially even intensity column of light is directed upwardly at rightanglestothe plane of the sheet 11. The pointer assembly attached to the upper end of the spindle moves, upon rotation of the spindle, in a plane above, and parallel to the surface 1 la of the sheet.As will be described in more detail, each pointer assembly includes 45 reflecting surfaces which reflect light passing upwardly through the circular aperture ofthe mask, at right angles into the needle ofthe assembly to illuminate the needle. The 45 reflecting surfaces of the pointer assembly have a sufficient angular dimension to ensure that when either is positioned aboveforex- ample the apex defined by the facets 16e and 17c then itwill be receiving light from one, orthe other, or both ofthe facets 1 6c, 1 7c. Thus the needle ofthe pointer assembly will beevenlyilluminatedthroug- houtthe whole are of movement of the spindle.

Referring now specifically to Figures 7 and 8 it can be seen that beneath the sheet 11 there is provided an instrument movement 21 having an upwardly projecting spindle 22. In use the spindle 22 projects through an aperture 12 in the sheet 11,andthrough an aperture in an opaque mask 1 1a positioned above the sheet 1 liThe pointer assembly includes a boss member 23 and a neeld member 24, both of which are formed from clear acrylic material.

As can be seen clearly in Figure 7 the boss member 23 has a blind bore 24 extending inwardly from its lower face, within which the spindle 22 is received in use. The boss member 23 extends radially outwardly from both sides of the bore 24, and at one side ofthe bore 24 the end face of the member 23 is inclined at 45" to the lowerface of the member 23 and so defines a reflecting surface 25 whereby light incident thereon in a direction parallel to the spindle 22 is reflected at right angles to pass along the length of the boss member 23 above the level of the closed end of the blind bore 24.To the opposite side of the blind bore 24from the surface 25 the member 23 is formed with an inclined slot 26 extending inwardly from the lower face of the member 23 through a distance equi- valentto the depth of the bore 24. The slot 26 defines a reflecting face 27 parallel to the reflecting face 25 which also reflects light lengthwise to the boss member 23.

The upperfaceofthe boss member 23 is parallel to the lowerface and defines a surface upon which a root portion 31 of the needle member 24 is secured.

The needle member 24 includes the root portion 31, and an integral, co-extensive, pointer portion 32.

When the root portion 31 is seated upon the upper surface of the boss member 23 then the needle member 24 extends transverse to, and intersects, the axis of the spindle 22. Thus the length ofthe needle member 24 is such that parts of the needle member 24 project in opposite directions from the centre of rotation of the pointer assembly, the major portion of the needle, that is to say the pointer portion together with part of the root portion projecting to one side of the axis of rotation while the remainder of the root portion projects to the opposite side ofthe axis of rotation. The whole of the lower face of the needle member 24, both in the root portion and the pointer portion is coated with reflective paint, but the free end of the root portion is polished.Integral with the end region of the boss member 23 remote from the reflecting surface 25 is a 90 prism member 28 comprising a first 45 reflecting surface 29 which reflects light from within the boss member 23 upwardly at right angles, and a second 45 reflecting surface 30 whichturns the upwardly reflecting light through 90 so that it is projected in the opposite direction to its direction of transmission within the boss member.

The end surface of the root portion 31 of the needle member 24 seats against part of the prism member 28 and receives lighttherefrom. Thus the whole length of the needle member 24 can be illuminated, so that the perceived effect is of an illuminated bar of colour projecting at considerable distance to one side of the axis of rotation of the pointer assembly, but extending backthrough the axis of rotation and beyond the axis of rotation in the opposite direction.

Where the pointer assembly is utilized in conjunction with a sheet 11 of the kind described above then light incident upon the reflecting surfaces 25 and 27 ofthe boss member 23 is that deflected from the facets 16, 17. It is to be understood howeverthat other forms of sheet could be employed with the pointer assembly if desired.

It is to be understood that in optical terms it is not sigificantthatthe prism member 28 is integral with the boss member23. The prism membercould instead be integral with the needle member 24, or, as shown in Figures 9 to lithe prism member could be in two parts, one integral with the needle member and the other integral with the boss member. In Fig ures 9 and 1 Othe prism member parts are indicated bythe reference numerals 28a and 28b respectively.

Figures 10 and ii also illustrate the provision of an opaque cover 33 which serves a dual function. Firstly the cover 33 serves to securethe needle member24 in the appropriate position on the boss member 23 thus obviating the need for an adhesive between the needle memberandthe boss memberwhich might impairthe reflection from the coated lower face of the needle member. Secondly, the cover 33 masks the pointer assembly in the region of the boss to prevent emanation of light from the pointer assembly except along the surface ofthe needle member 24.

The cover 33 will thus tend to merge into the background defined by the mask 1 a, heightening the illusion that the pointer ofthe instrument is simply an elongate bar of illuminated colour having an axis of rotation at right angles to the bar, and intersecting the baratthe point spaced inwardlyfrom one end thereof. A similar cover arrangement will be provided in the pointer assembly of Figure 7 and 8 and in each case the cover will be of generally circu larform so as to overliethe circular aperture in the mask 1 la thereby preventing direct escape of light from the aperture in the mask 1 ia alongside the boss and needle members ofthe pointer assembly. Desirably the cover is a snapfit on the assembly of the needle member and the boss member.

It isto be recognised thatthe pointer assembly of Figure 7 and 8 or the pointer assembly of Figures 9 to 11, can be used with instrument assemblies other than that described with reference to Figures 1 to 6.

Claims (9)

1. An instrument pointer assembly comprising a light conductive boss memberwherebythe pointer assembly can be attached to a spindle for rotation about an axis and a light conductive needle member comprising a root portion and a co-extensive pointer portion, said root portion being attached to said boss member so that the needle member extends at right angles to said axis with the root portion intersecting said axis and the pointer portion extending radially outwardlyfrom the axis, said boss member having first and second spaced and parallel reflecting surfaces at 45 to said axis whereby light travelling parallel to said axis and incident upon said surfaces is reflected within the boss member at right angles to said axis and in a direction opposite to that in which said pointer portion of said needle member extends relative to said axis, the assembly further including 90 prism means for deflecting said light reflected from said first and second surfaces and conducted within the boss member, along the length of said needle memberfrom the end ofthe root portion which is remote from the pointer portion so that said light can illuminate the whole ofthe lower face ofthe needle member including that region of the lower face defined by the root portion, which region intersects said axis.

2. An assembly as claimed in claim 1 wherein saidfirst and second surfaces are positioned at opposite sides respectively of said axis such that light reflected from one of said first and second surfaces intersects said axis en route to said prism means.

3. An assembly as claimed in claim 2 wherein said boss member has therein a blind boreforreceiv- ing said spindle and said one of said first and second surfaces reflects light in a region of the boss member lying beyond the closed end of said bore.

4. An assembly as claimed in any one of claims 1 to 3 wherein said boss member and said needle member are separately formed members, the needle member being attached to the boss member in use by a cover engaging both members.

5. An assembly as claimed in any one of claims 1 to 4wherein said prism means is defined by respective 45 reflecting surfaces on the boss member and the root portion of the needle member, said surfaces subtending 90 between them.

6. An assembly as claimed in any one of claims 1 to 4 wherein said prism means is integral with one of boss member and said needle member.

7. An instrument pointerassemblysubstantially as hereinbefore described with reference totheaccompanying drawings.

8. An instrument incorporating a pointer assembly as claimed in any one of claims 1 to7.

9. An instrument comprising a pointer assembly as ciaimed in any one of Claims 1 to 7 and a sheet of ilghtconductive material having first and second spaced regions at which light enters the sheet and a third region to which lightfrom said first and second regions isconductedwithin the sheet, one face ofthe sheet being recessed at said third region to define first and second sets of light reflective facets for reflecting light from the sheet in a direction awayfrom said oneface of the sheet, said facets being generally planarand being disposed atsubstantially 45"tothe sheetthickness, the facets of the first set offacets being presented towards said first region so as to reflect light emanating from said first region and the facets of said second set being presented toward said second region so asto reflect light emanating from said second region, said pointer assembly having its axis of movementtransverseto the sheet and extending between said sets of facets and said first and second parallel reflecting surfaces of the pointer boss member receiving light reflected from said facets.