Weighing scales incorporating printers

A price computing weighing scale has a platform 10 and a m in housing 14 and also incorporates a printer unit 16 located between the platform 10 and the main housing 14 so as to be removable as a unit whereby the scale can be supplied with or without a printing facility. Location of the printer unit 16 within the area beneath the platform 10 minimises the counter space occupied by the weighing scale and printer.

This invention relates to a weighing scale having a facility for providing 
a printed record of each weighing effected. 
There is an increasing demand from retail businesses for a printed record 
to be provided for each weighing. Hitherto this demand has been met either 
by providing a "stand alone" printing unit separate from the weighing 
scale but linked thereto by an electrical signal transmission cable or by 
incorporating the printer in the weighing scale. With the exception of the 
weighing scale mentioned below, as far as we are aware in all examples of 
weighing scales with built-in printers, the printer unit is located along 
side the weighing unit and such scales, and also those with separate 
printers, suffer from the drawback that the counter space required is 
increased because of the presence of the printing unit, the ticket 
capacity is very limited (the printing unit being kept small to avoid 
taking up excessive counter space) and the need for access to the interior 
of the printing unit to replenish the ticket supply and ink makes the 
sealing of the unit against ingress of foreign matter difficult. U.S. Pat. 
No. 3,461,984 shows a typical prior art arrangement combining a weighing 
scale and a printer. 
The exception referred to above is the scale disclosed in U.S. Pat. No. 
2,549,752 which employs a mechanical drum computing mechanism operated by 
the scale pan. The drums in this case have a dual purpose in that they are 
provided with printing type so that a print-out can be derived. This type 
of mechanism suffers from the drawback that the large displacements of the 
scale pan inevitably make it very difficult to prevent the ingress of 
foreign matter while at the same time providing ready access to the 
printer, and the scale cannot be readily converted to one without a 
printing facility as the printing mechanism is inextricably linked with 
the weighing mechanism. Moreover, the printing medium feed mechanism has 
to be located at the base of the scale and is relatively difficult to 
maintain. As a result of the location of the feed mechanism, the printed 
labels issue adjacent the base of the housing at one side thereof and in 
general this will be inconvenient to the user as a space must then be kept 
clear in that region to allow the printed labels to be collected. 
The present invention seeks to provide an improved weighing scale with a 
built in printing facility which overcomes the above drawbacks. 
According to the present invention we provide a weighing scale including 
printing means, characterised in that the load receiving member or 
platform of the scale is mounted on a load cell for providing an 
electrical representation of the applied load and at least part of the, 
and preferably the entire, printing means is located within an area 
directly beneath the load receiving platform. 
With a load cell mounting for the platform, the degree of movement of the 
platform even for loads at the top end of its capacity is very small and 
the presence of the printer beneath the platform does not therefore create 
any difficulties as far as platform movement is concerned. 
In the preferred embodiment, the printing means comprises a printing 
device, means for storing a supply of printing medium (e.g. a supply of 
tickets or fan folded paper) and means for feeding the printing medium 
through the printing device whereby the result of each weighing 
transaction may be recorded, and all of the above mentioned integers of 
the printing means are housed beneath the load receiving platform on a 
deck within an area which does not extend beyond the perimeter of said 
platform, the deck and the printing means being removable as a unit from 
the scale so that the scale can be used with or without a printing 
facility. 
The platform is conveniently mounted on the load cell by one or more 
generally vertically extending members so as to be spaced above the main 
housing of the scale and the printer is accommodated within the space 
between the main housing and the platform.

Referring to FIG. 1, the weighing scale according to the present invention 
comprises a weighing platform 10 mounted on vertically extending rods 11 
above the scale housing 12. The scale housing 12 comprises a lower section 
14 and an upper section 16. The lower housing section 14 houses for 
example a bending beam type load cell (not shown) to which the rods 11 are 
connected, the beam being provided with strain gauges which are wired in 
for example a Wheatstone bridge configuration so as to provide an output 
signal representing the applied load. The section 14 also houses circuitry 
associated with the load cell, circuitry associated with the visual 
display 18 for displaying weight and also for example price per unit 
weight and total cost, and circuitry for computing total price etc. A 
keyboard 20 (the individual keys of which are not illustrated) is provided 
by means of which the user can key in price per unit weight information 
and other data. 
The upper section 16 is in the form of an inverted tray shaped cover which 
may be of transparent or translucent plastics material and accommodates a 
printing unit. As shown in FIG. 2, in one form the printer comprises a 
printing head 22, a spool 24 for mounting a roll 26 of adhesive labels 
carried by a continuous packing strip 27 of for example silicone paper, 
and a drive and pinch wheel system 28 which is operable in stepwise manner 
to draw the strip 27 from the roll 26 and thereby increment the labels one 
by one through the printing head 22. The drive motor and associated 
control circuitry for the pinch wheel system 28 may be housed within the 
lower section 14 and the printing head 22 may be supplied with control 
signals from the electronic circuitry representing the weight and price 
data and other information to be printed out. A sensor 30 is provided in 
order to ensure proper registration of the labels with the printing head. 
The strip feed path conveniently includes a sharp bend as defined by a 
guide 32 so that the backing strip is caused to pull away from the labels 
33 and leave the latter projecting in the direction of the original path 
of movement. By providing an opening 34 in the cover 16 adjacent the guide 
32, the label can be caused to project externally for collection by the 
scale user. 
FIG. 3 shows a modified embodiment which is similar to that of FIG. 2 
except that the spent backing strip is rewound into roll form by means of 
a rewinder mechanism 36. 
In both embodiments, the cover 16 is formed with a pair of holes through 
which extend the vertical rods 11 connecting the scale pan to the load 
cell. The pan itself may seat on a X-shaped structure (not shown) which is 
supported on the rods and this structure and the cover 16 may include 
raised formations surrounding the rods 11 which formations nest with each 
other to prevent ingress of water and such like. The lower edge of the 
cover 16 may be on the lower housing section 14 via a labyrinth seal to 
prevent ingress of foreign matter whilst allowing ready removal of the 
cover 16. Access to the printing mechanism may be obtained by lifting off 
the weighing pan and supporting structure and the cover 16 and the 
arrangement may be such that this can be effected in a single operation. 
Also the printing deck is conveniently removably mounted on the housing 
section 14 by releasable fasteners to enable the deck and section 16 to be 
removed when a printing facility is not required. The rods 11 may for this 
purpose include spacers (not shown) which may also be removed in this 
event to lower the scale pan. 
The printer may be adapted to handle "fan-folded" paper or modified to 
provide a tally roll record of weighing transactions. 
Referring now to FIGS. 4 and 5 the same reference numerals are used in 
these figures to identify those components which are equivalent to the 
components shown in FIGS. 2 and 3. The scale pan 10 is mounted on an 
X-shaped structure 50, part only of which is illustrated, and the 
structure 50 is supported from a load cell 52 via rods 11. Various forms 
of load cell may be employed but in FIG. 4 a load cell of the type 
disclosed in our prior European published patent application No. 15337 is 
shown (in part only). The rods 11 pass through a pair of guide sleeves 54 
on the printer deck 56 and extend into the housing 14 which accommodates 
the load cell 52. The deck 56 is removably mounted on the housing 14 and 
for this purpose is supported at its periphery by a flange 58 extending 
around the edge of a top opening in the housing 14. Fasteners 60 secure 
the deck 56 to the housing 14. 
The deck 56 mounts various components of the label carrying strip feed and 
printing assembly including a dot matrix printer 22, storage spool 24, 
take up spool 36, sensors 30 for sensing registry of the labels with the 
printer 22, guides 32, 62, 64 and 66 and a drive motor 68 for driving the 
take-up spool and the ribbon feed mechanism of the printer 22. The guides 
32 and 66 are rotatable about their axes and the guides 64 and 66 may 
include rotatable sleeves for contacting the strip. The guide 32 it will 
be observed is polygonally shaped so as to assist in deflecting the 
printed labels away from the backing strip in the manner described in the 
previous embodiments whereby the printed label is projected through an 
opening in the cover 16 for collection by the operator. 
The sensors 30 as mentioned enable the label carrying strip to be 
coordinated with the printer so that the relevant printed matter is 
entered at the desired location on the labels. The guide 32 as well as 
serving to peel the labels from the backing strip also forms an anvil for 
supporting the labels during printing. 
The cover 16 may simply rest on the housing section 14 in the manner 
indicated in FIG. 4 and is provided with opening 70 through which the 
bushes 54 and rods 11 extend. The cover 16 may be composed of transparent 
plastics material so as to aid inspection of the amount of label carrying 
strip stored. The circuitry associated with the printer and strip feeding 
assembly and the load cell, keyboard etc. is mounted on a printed circuit 
board 72 which is fastened within the housing 14 and the arrangement is 
such that the connections between the circuitry and the electrical 
components (e.g. the drive motor and sensors 30) of the printer and strip 
feed assembly are readily disconnectable, e.g. via a single male and 
female connector. 
The rods 11 include detachable extension pieces 74 to which the structure 
50 is releasably connected so that, in circumstances to be discussed 
below, the structure can be secured to the rods 11 without the 
interposition of the extension pieces. In some circumstances, the end user 
of the weighing scale may not require a printing facility. To enable the 
scale to be adapted to meet this requirement, in each embodiment described 
above the printer and feed assembly together with the cover 16 are 
designed so as to be readily removable from the housing 14. Thus, with 
reference to the embodiment of FIGS. 4 and 5, the printer and feed 
assembly on the housing 16 can be removed simply by removing the pan 10 
and structure 50, removing the cover 16, releasing the fasteners 60, 
lifting out the printing deck 56 and disconnecting the previously 
mentioned male/female connector. The pan 10 can then be lowered with 
respect to the housing 14 simply by removing the extension pieces 74 and 
fastening the structure 50 directly to the upper ends of the rods 11. In 
this event, the printer and strip feed control circuitry on the board 72 
will be redundant but nevertheless will be available if the end user 
wishes to take advantage of the printing facilities subsequently. 
Alternatively, the printer and strip feed control circuitry may be 
provided on a separate board attached to the printer deck 56 so as to be 
removable with the deck and, in this case, a male/female connector may be 
provided to interconnect the two circuit boards for the supply of 
electrical power and data to be printed out.