WO1994025834A1

WO1994025834A1 - Level weighing device

Info

Publication number: WO1994025834A1
Application number: PCT/US1994/003741
Authority: WO
Inventors: Uri Zefira
Original assignee: Friedman, Mark, M.
Priority date: 1993-04-23
Filing date: 1994-04-06
Publication date: 1994-11-10
Also published as: IL105508A0; IL105508A

Abstract

A weighing device (2) for accurately weighing an object, which includes a support base (4), a weighing platform (8) for supporting the objet and a load cell (6) mounted on the base (4) for measuring the weight of the object. The load cell (6) includes an anchoring section (18) for anchoring the load cell (6) to the support base (4). The device further includes an inclinometer (28) horizontally positioned in correspondence with the anchoring section (18) of the load cell (6) for measuring the levelness of the load cell (6). A display means (32) is connected to the inclinometer (28) for conveying information necessary to obtain an accurate weight measurement.

Description

LEVEL WEIGHING DEVICE

FIELD AND BACKGROUND OF THE INVENTION

The present invention is related to a weighing device, and

particularly to a weighing device which includes an inclinometer. The

invention is also related to a method for accurately weighing an object.

It is well known that in order for a weighing scale to accurately

measure the weight of an object, it must be level. By the term 'level' it is

meant parallel with the plane of the horizon, or in other words, perfectly

horizontal. The scale must be level because the load cell, which measures

the load, only measures directly vertical forces applied to it. If the force

applied to the load cell is at an angle, only the vertical component of the

force (the force x the cosine of the angle) will be measured.

In order to ensure the levelness of a scale, it is customary to include

on the surface of the scale a small liquid-filled transparent chamber or vial

containing a bubble. A circle or other mark is located on the surface of the

chamber so that when the scale is level, the bubble is positioned within the

mark. The levelness of the scale can be adjusted, for example, by adjusting

the lengths of the legs of the scale. Although this method results in a level

scale, it is quite time-consuming and involves much trial-and-error until the

legs of the scale are adjusted to their proper lengths.

Tilt sensors or inclinometers are instruments, usually electrical or

electronic, capable of measuring quantitatively the angle of tilt of an object

and outputting the result to an appropriate display. Various types of these instruments based on various physical principles such as electrical resistance of a liquid or the displacement of a pendulum are known. They are commonly installed in ships or aircraft, or used with construction lasers

or vertical gyros.

It is an object of the invention to provide a weighing device which

can be levelled quickly and easily.

It is another object of the invention to provide a weighing device

will give an accurate weight measurement without being levelled.

It is a further object of the invention to provide a new type of

inclinometer.

SUMMARY OF THE INVENTION

In accordance with this invention there is thus provided a weighing

device for accurately weighing an object comprising: a support base; a

weighing platform for supporting the object; a load cell mounted on the

base for measuring the weight of the object, the load cell comprising an

anchoring section for anchoring the load cell to the support base; an

inclinometer horizontally positioned in correspondence with the anchoring

section of the load cell for measuring the levelness of the load cell; and a

display means connected to the inclinometer for conveying information

necessary to obtain an accurate weight measurement. In accordance with this invention there is also provided a method for

accurately weighing an object using the above weighing device.

By combining an inclinometer with a weighing scale, the levelling

of the scale is greatly simplified and speeded up. In addition, it is possible

to integrate the output of the load cell and the inclinometer in a processor

so that the weight measurement is automatically corrected for the tilt of the

scale, in which case the need to adjust the level of the scale is obviated.

In addition to the aforementioned types of inclinometers, a load cell

can be used in a similar manner to measure the tilt of an object. The load

cell can be calibrated to measure an internal weight (or its own weight)

while in a horizontal state. If the load cell is then tilted, it will measure a

weight less than the calibrated weight by a factor related to the cosine of

the angle of tilt. This output can then be used to indicate the degree of tilt.

Further features and advantages of the invention will be apparent

from the description below.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, with

reference to the accompanying drawings, wherein:

Figure 1 is a schematic, exploded, perspective view of a prior art

weighing scale; Figure 2 is a schematic, perspective view of one embodiment of the

invention; and

Figure 3 is a schematic, perspective view of another embodiment of

the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to Fig. 1, there is illustrated a weighing device,

generally designated 2, comprising a support base 4, a load cell 6 mounted

on the base, and a weighing platform 8 supported by the load cell.

The base 4 is supported on four rotatable legs 10, each comprising

a threaded rod 12 and a base element 14. The legs are threaded

respectively into four threaded holes 16 located at the corners of the base

4. The heights of the corners of the base, and therefore its levelness, are

adjusted by the extent of the threading of the rods 12 into the holes 16.

The load cell 6 includes two sections, an anchoring section 18 which

anchors the load cell to the base, and a load-bearing section 20 which is

attached to the weighing platform 8 for measuring the weight of the object

on the platform. The upper surface of the load bearing section 20 projects

slightly above the remainder of the load cell and its lower surface does not

rest on the base, so that it is free to bear the weight of the object. An

electrical cord 22 transmits the weight measurement to a display means

(not shown). The weighing platform 8 rests on the load-bearing section 20 of the

load cell and is attached to it. The platform includes a levelling chamber

24 for indicating the horizontal position of the platform.

Fig. 2 illustrates a weighing device 26 without the weighing

platform. Mounted on the base 4, in addition to the load cell 6, is an

inclinometer 28, in this case, another load cell calibrated as explained

above. Both the load cell and the inclinometer are fixed to the support base

4 so that their horizontal positions are in correspondence one to the other.

It is to be understood that the same result is obtained by securing the

inclinometer to the load cell rather than to the base.

Wires 30 extend from the load cell and inclinometer to a display

means 32 which has a first display 34 for displaying the weight measured

by the scale and a second display 36 for indicating which legs 10 of the

base should be threaded in which direction in order to bring the scale to

levelness. The first display 34 is connected to the load cell 6 and the

second display 36 is connected through a processor in the display means

to the inclinometer 28.

Referring now to Fig. 3, there is illustrated a weighing device 26 in

which the load cell 6 and inclinometer 28, which is also a load cell, form

one integral unit. This simplifies manufacturing and reduces costs. Both the

load cell and the inclinometer are fixed to the base 4 by a common

anchoring section 18. A common cable 38 including wires from the inclinometer 28 and from the load-bearing section 20 of the load cell extends from the scale to a processor 40. The processor integrates the

output from both devices and corrects the weight measured by the load-

bearing section for inaccuracies due to any deviation of the load cell from

levelness as measured by the inclinometer. The corrected output is then

transmitted to the display means 32 where the corrected weight is displayed

on a display 34.

The above configuration can of course be used with a display means

as illustrated in Fig. 2, and the configuration illustrated in Fig. 2 can be

used with the display means of Fig. 3. Furthermore, the inclinometer can

be of any of the standard types, and not just of the load cell type.

While the present invention has been described in terms of two

preferred embodiments, it is expected that modifications and improvements

will occur to those skilled in the art upon consideration of this disclosure.

Claims

WHAT IS CLAIMED IS:

1. A weighing device for accurately weighing an object

comprising:

a support base;

a weighing platform for supporting said object;

a load cell mounted on said base for measuring the weight of

said object, said load cell comprising an anchoring section for

anchoring said load cell to said support base:

an inclinometer horizontally positioned in correspondence

with said anchoring section of said load cell for measuring the

levelness of said load cell; and

a display means connected to said inclinometer for conveying

information necessary to obtain an accurate weight measurement.

2. A device according to claim 1 , wherein said inclinometer and

said load cell form one integral unit.

3. A device according to claim 1, wherein said inclinometer is

secured to said load cell.

4. A device according to claim 1, wherein said inclinometer and

said load cell are fixed to said support base.

5. A device according to claim 1, wherein said display indicates

the horizontal position of said anchoring section of said load cell.

6. A device according to claim 5, wherein said display indicates

the positional corrections necessary to bring said load cell to levelness.

7. A device according to claims 1, wherein said display is

additionally connected to said load cell.

8. A device according to claim 7, wherein said display indicates

the weight of said object, said weight being corrected for inaccuracies due

to a deviation from levelness of said load cell.

9. A device according to claims 1, wherein said inclinometer is

a load cell.

10. A method for accurately weighing an object using the

weighing device of claim 1.

11. A method for measuring the levelness of an object using a

load cell as an inclinometer.