GB2084332A - Indicating weight - Google Patents

Abstract

The weight readout arrangement 14 of a weighing device comprises fixed concentric graduated scales 21 and 22 respectively swept by a fast pointer 16 and a slower pointer 15. Each pointer 15, 16 is fixed to a respective one of a pair of coaxial shafts which are fixed to respective wheels of a speed-increasing gear train. The weight indicated comprises the sum of the readings indicated by the two pointers 15 and 16. The first driving member of the gear train is a rack which is connected to the weighing mechanism. The gear train may be a compound train or an epicyclic gear train having its planet wheels meshing with an internal gear wheel which is fixed against rotation when the pointers are aligned with their respective zero graduations and held so fixed during weighing. <IMAGE>

Description

SPECIFICATION Weighing scales DESCRIPTION This invention relates to weighing scales.

Weight readout arrangements of bathroom scales need to be easily readable from a distance of several feet whilst being able to indicate weights within a range of the order of three hundred pounds for them to be usable by most people. Also they should be cheap if the bathroom scales are to be marketable. These criteria have meant that the graduations of the graduated scales employed have not been as small as might otherwise have been desired so that the units of the weight readout are larger than ideal.

Similar problems are experienced on a smaller scale with kitchen scales and the like.

An object of this invention is to provide an inexpensive weight readout arrangement for weighing scales, that readout arrangement being arranged in graduations so as to be readily readable from a distance and providing a usefully large weight range whilst allowing the use of graduations representing small weight units.

According to this invention weighing scales comprise a weighing mechanism and a weight readout arrangement, the weight readout arrangement comprising indicating means and two graduated scales, the indicating means and the two graduated scales being supported for relative movement between the indicating means and each of the graduated scales and there being drive transmitting and coupling means connecting the movable elements of the relatively movable indicating means and graduated scales to the weighing mechanism so that, during weighing, those movable elements are driven by the weighing mechanism to effect relative movement between the indicating means and the two graduated scales which is a function of the weight being weighed, the graduations of the two graduated scales being such that the maximum reading of one of them equals a unit of the other so that each unit of said one graduated scale is a fraction of a unit of said other graduated scale and the indicating means co-operating with the two graduated scales so as to indicate a weight reading on each of the graduated scales simultaneously and said drive transmitting and coupling means being arranged so that the weight being weighed comprises the sum of the readings indicated on the two graduated scales by the indicating means.

Preferably the movable elements comprise two pointers which together constitute the indicating means, each pointer being arranged to sweep a respective one of the two graduated scales that are static. Alternatively the movable elements may comprise two dials which are supported for revolution past a fixed pointer, each dial carrying a respective one of the graduated scales.

Conveniently the movable elements are geared so that one of them executes one revolution whilst one unit of the scale associated with the other traverses or is traversed by the respective indicating means. Preferably the movable elements are supported for coaxial movement, the two graduated scales being concentric.

There may be a second such weight readout arrangement comprising further indicating means and two further graduated scales, the further indicating means and the two further graduated scales being supported for relative movement between the further indicating means and each of the two further graduated scales, the movable elements of the further indicating means and the two further graduated scales being connected to the weighing mechanism by further drive transmitting and coupling means, in a manner similar to the connection of the movable elements of the first mentioned weight readout arrangement to the weighing mechanism the second such weight readout arrangement being arranged to indicate weight in a different system of weighing units (for example in the metric system) from the system of weighing units (say the imperial system) in which the first mentioned weight readout arrangement is arranged to indicate weight.

Conveniently the weighing scales may be personal scales of the kind used as bathroom scales. Alternatively the weighing scales may be kitchen scales or the like.

Preferably the drive transmitting and coupling arrangement comprises a speed increasing gear train including, as its first driving element, a rack which co-operates with the weighing mechanism so that it is displaced longitudinally during weighing, the displacement being a function of the weight being weighed, wherein a first of the two pointers, which is the slower, is fixed to a first intermediate gear wheel of the train with which the rack meshes and the second, faster pointer is fixed to the final gear wheel of the train, the train being arranged such that said first intermediate gear wheel and said final gear wheel are driven to rotate in the same sense. The gear train may be a compound train.Alternatively, the gear train may be an epicyclic gear train including at least one second intermediate gear wheel which is carried by an arm which is fixed to and projects radiallyoutwardly from said first intermediate gear wheel, the or each said second intermediate gear wheel meshing with a sun wheel about which it revolves, and with an internal gear wheel, the sun wheel being said final gear wheel. The internal gear wheel may be supported by support means which are fixed relative to the graduated scales, and clamping means provided for clamping said internal gear wheel against rotation relative to said support means during weighing, said internal gear wheel being free for rotation about its axis relative to said support means when not clamped by said clamping means.

One form of bathroom scales in which this invention is embodied, and a modification are described now by way of example with reference to the accompanying drawings, of which: Figure 1 is a perspective view of the bathroom scales; Figure 2 is a fragmentary plan view of a gear train incorporated in the bathroom scales shown in Figure 1; Figure 3 is a section on the line Ill-Ill in Figure 2; and Figure 4 is a view similar to Figure 3 of another form of gear train used in a modified form of the bathroom scales shown in Figure 1.

Figure 1 shows bathroom scales comprising a base 11 which stands on a floor, and a ioading platform 12 which is supported from the base 11 by a conventional weighing mechanism (not shown).

A part 1 3 of the base 11 which is not covered by the platform 12 has a weight readout arrangement 14 mounted on it. The weight readout arrangement 14 comprises two indicating pointers 1 5 and 1 6 each projecting radially from a respective one of two coaxial shafts 1 7 and 1 8 (see Figures 2 and 3) so as to extend over a respective one of two circuiar graduated scales 21 and 22 (see Figure 1) which are depicted concentrically on a suitable backplate so as to be coaxial with the coaxial shafts 17 and 18. Each pointer 1 5, 1 6 is connected to the weighing mechanism by a speed increasing compound gear train which is a drive transmitting and coupling mechanism and which is described below with reference to Figures 2 and 3.

The inner graduated scale 21 is graduated in first order units, say in pounds where the scale is graduated for weighing according to the imperial scale, and the other graduated scale 22 is graduated in second order units, namely stones where the scale is graduated according to the imperial system. The gear train is arranged so that the pointer 16 that sweeps the graduated scale 21 which is graduated in the first order units executes one revolution about its axis whilst the other pointer 1 5 traverses one unit of the other graduated scale 22.

Figures 2 and 3 show that the first, or input member of the gear train comprises a rack 23 which is connected to the weighing mechanism in the usual way so that it is displaced rectilinearly by the weighing mechanism during weighing by a distance which is a measure of the weight on the platform 12.

The rack 23 meshes with the smaller diameter gear wheel portion of a compound spur gear wheel 24 which is the first intermediate gear wheel of the gear train. The compound gear wheel 24 is fixed coaxially to the shaft 1 7 which is a slim vertical spindle. The shaft 1 7 is journaled in a spaced pair of horizontal support plates 25 and 26 which extend respectively above and below the compound gear wheel 24 and which are mounted in the base 11. The larger diameter gear wheel portion of the compound gear wheel 24 meshes with a smaller gear wheel portion of a second compound intermediate gear wheel 27 of the gear train.The larger gear wheel portion of the second compound wheel 27 meshes with an annular spur gear wheel 28 which is journaled on the shaft 17 above the support plate 25 and which, being integral with the hollow shaft 18, is the final gear wheel of the compound gear train. The gear train is conveniently arranged so that the hollow shaft 18, and its pointer 1 6, are driven at fourteen times the speed of the shaft 1 7 and its pointer 1 5.

The upper end of the hollow shaft 18 has splines 29 formed on its outer surface and those splines 29 are engaged in co-operating formations in the pointer 1 6. The pointer 1 5 is shown fixed to the shaft 17 by a grub screw 30, but other fixing arrangements, such as a locking taper, could be used. Accurate location of the pointer 15 relative to the spindle shaft 1 7 and in line with the respective zero graduation when the pointer 1 6 is aligned with its respective zero graduation during assembly is difficult because the shaft 1 7 is small and the range of possible locations of the pointer 1 5 relative to the shaft 1 7 is infinite.Moreover accurate fixing of the pointer 1 5 to the shaft 1 7 when so located is also difficult. We believe these problems can be avoided if bathroom scales are modified so that the special form of epicyclic gear train shown in Figure 4 is used instead of the compound gear train shown in Figures 2 and 3.

The epicyclic gear train shown in Figure 4 comprises a rack 23A, which is functionally equivalent to the rack 23 and which meshes with a first intermediate spur gear wheel 31 which carries two radial arms 32 and 33 and a coaxial hollow shaft 1 7A which is functionally equivalent to the shaft 17. Splines 34 are formed at the upper end of the shaft 1 7A and are engaged with corresponding formations in the slower pointer 1 5A. The final gear of the gear train is an annular spur gear wheel 35 which is journaled on the hollow shaft 17A, is integral with a hollow shaft 1 8A which is functionally equivalent to the hollow shaft 18, and is the sun wheel of the epicyclic gear train.There are two further intermediate spur gear wheels 36 and 37 which both mesh with the sun gear 35 in the manner of planet gear wheels and which are each journaled on a respective stub shaft 38, 39 which is mounted at the outer end of a respective one of the radial arms 32 and 33. The two planet gear wheels 36 and 37 both mesh with an internal gear wheel 41 which is seated in an annular shoulder 42 formed in the base part 13A and which is normally fixed relative to the base part 1 3A by a clamping screw 43. Splines 29A formed at the upper end of the outer hollow shafts 1 8A are engaged in corresponding formations in the faster pointer 16A.

The step of setting the two pointers 1 5A and 1 6A to zero during assembly of the scales is carried out before the internal gear wheel 41 is clamped to the base part 1 3A but after the remainder of the epicyclic gear train is assembled with the pointers 1 5A and 1 6A fitted to the splined ends of the respective shafts 1 7A and 18A. Firstly the slower pointer 1 5A is set to zero on the respective graduated scale by manipulation of the usual adjusting knob which is provided for "in-service" adjustment and which drives that pointer 1 5A through the rack 23A, the first intermediate gear wheel 31 and the integral shaft 17A. The slow pointer 15A is then locked in that zero location, either by clamping the rack 23A or the carrier arms 32 and 33 using a separate clamping jig (not shown).The faster pointer 1 6A is then set to zero on the respective graduated scale by turning one of the sun gear wheel 35, the planet gear wheels 36 and 37 or the internal gear wheel 41 with the aid of a key (not shown), the internal gear wheel 41 being free to rotate within the annular shoulder 42. When the faster pointer 1 6A is aligned with the respective zero graduation, the internal gear wheel is locked against movement relative to the base part 1 3A by tightening the clamping screw 43 which completes assembly of the epicyclic gear train and its installation in the bathroom scales for use. The separate clamping jig and the key are then removed, thus freeing the first intermediate gear wheel 31, the carrier arms 32 and 33 and the planet gears 36 and 37 for rotation about the axes of the gear wheel 31 and the sun gear 35 during weighing.

Claims (9)

1. Weighing scales comprising a weighing mechanism and a weight readout arrangement the weight readout arrangement comprising indicating means and two graduated scales, the indicating means and the two graduated scales being supported for relative movement between the indicating means and each of the graduated scales and there being drive transmitting and coupling means connecting the movable elements of the relatively movable indicating means and graduated scales to the weighing mechanism so that, during weighing, those movable elements are driven by the weighing mechanism to effect relative movement between the indicating means and the two graduated scales which is a function of the weight being weighed, the graduations of the two graduated scales being such that the maximum reading of one of them equals a unit of the other so that each unit of said one graduated scale is a fraction of a unit of said other graduated scale and the indicating means co-operating with the two graduated scales so as to indicate a weight reading on each of the graduated scales simultaneously and said drive transmitting and coupling means being arranged so that the weight being weighed comprises the sum of the readings indicated on the two graduated scales by the indicating means.

2. Weighing scales according to Claim 1, wherein the movable elements comprise two pointers which together constitute the indicating means, each pointer being arranged to sweep a respective one of the two graduated scales that are static.

3. Weighing scales according to Claim 1 or Claim 2, wherein the movable elements are geared so that one of them executes one revolution whilst one unit of the scale associated with the other traverses or is traversed by the respective indicating means.

4. Weighing scales according to Claim 1, Claim 2 or Claim 3, wherein the movable elements are supported for coaxial movement, the two graduated scales being concentric.

5. Weighing scales according to Claim 2 or either of Claims 3 and 4 when appended to Claim 2, in which the drive transmitting and coupling arrangement comprises a speed increasing gear train including, as its first driving element, a rack which co-operates with the weighing mechanism so that it is displaced longitudinally during weighing, the displacement being a function of the weight being weighed, wherein a first of the two pointers, which is the slower, is fixed to a first intermediate gear wheel of the train with which the rack meshes and the second, faster pointer is fixed to the final gear wheel of the train, the train being arranged such that said first intermediate gear wheel and said final gear wheel are driven to rotate in the same sense.

6. Weighing scales according to Claim 5, wherein the gear train is a compound train.

7. Weighing scales according to Claim 5, wherein the gear train is an epicyclic gear train including at least one second intermediate gear wheel which is carried by an arm which is fixed to and projects radially-outwardly from said first intermediate gear wheel, the or each said second intermediate gear wheel meshing with a sun wheel about which it revolves, and with an internal gear wheel, the sun wheel being said final gear wheel.

8. Weighing scales according to Claim 7, wherein said internal gear wheel is supported by support means which are fixed relative to the graduated scales, and clamping means are provided for clamping said internal gear wheel against rotation relative to said support means during weighing, said internal gear wheel being free for rotation about its axis relative to said support means when not clamped by said clamping means.

9. Bathroom scales substantially as described hereinbefore with reference to and as illustrated in Figures 1 to 3 or in Figures 1 and 4 of the accompanying drawings.