The present invention relates to a weighing apparatus. Items to be weighed are conveyed onto a weighing surface, and the apparatus comprises displacement means for removing weighed items from the weighing surface into a receiving means and returning to its original position withough physically interacting with subsequent items placed on the weighing surface. In a preferred embodiment, the displacement means are comprised of a comb-like structure, which returns to its original position after removal of weighed items from the weighing surface by movement under and along the weighing surface, which contains a plurality of apertures which the displacement member can move through and along. The invention further relates to a method of operating a weighing apparatus according to the invention.

Background of the invention In various industries, such as the food industry, it is important to be able to weigh items that are produced in a reliable and efficient manner. For example, it is important to establish the weight of individual items for subsequent labelling and/or quality control. Furthermore, it may be of importance to record the individual weight of items that will later be packaged together, and where it is important that the final package be within a given weight range. In other applications, the weight of a receiver is recorded as items are continously fed into the receiver, until a predefined limit has been reached.

Various methods and appliances have been developed for use in specific manufacturing lines, and both static weighing means and dynamic weighing means have been developed. The former are more reliable and provide a more accurate determination of weight, while the latter is useful in high-througput settings, for example as part of conveyor systems, where production items are being moved at a large speed.

Determining the weight of an item by means of a static weight requires three distinct operations to be performed: 1. Loading of the weighing means with one or several items to be weighed 2. Determination of the weight of the items put on the weighing means 3. Removal of the items from the weighing means

These three steps either require manual intervention, i. e. manual loading and removal, or automatization by means of e. g. robotic arms. In both cases, the weighing operation is rather slow and thus inefficient.

Loading of a weighing means may be performed at high speed using conveying means, either by manual conveying or by loading via a conveyor. However, in such cases, the removal of items from the weighing means becomes the rate- limiting step in the weighing procedure.

There is therefore a need for a weighing apparatus which (i) allows accurate weight determination by means of a static weight, and (ii) provides means for rapid removal of items from the weighing means after determining the weight of one or more items.

It is an object of the present invention to provide an apparatus for weighing items which allows rapid operation of a weighing means, including loading, weight determination and removal. The present invention further provides a method for operation of a weighing apparatus according to the invention.

Description of the Invention In a first aspect, the present invention provides a weighing apparatus comprising loading means for delivery of items to be weighed onto a weighing surface ; weighing means comprising a weighing surface for accepting items to be weighed and means for recording and storing the weight of items to be weighed; a displacement member for removing weighed items from the weighing surface by movement from an original position to a displacement position, the displacement member being mounted on a motor for providing horisontal and/or lateral movement of the displacement member; receiving means for receiving items displaced from the weighing surface by the displacement member.

In one embodiment of the invention, the displacement member comprises means for movement from the displacement position to an original position, after displacement of a first item or items from said weighing surface, without entering the space occupied by subsequent item or items to be weighed, after said item or

items have been positioned on said weighing surface. The advantage of such means is that an increased throughput of the weighing means is possible, since the weighing platform can be loaded and the weight of items recorded, while the displacement member moves from its displacement position back to the original position.

Thus, in one preferred embodiment, the movement of the displacement member is characterized by transversal movement from an original position across said weighing surface, thus essentially removing the weighed items from the weighing surface; movement of said displacement member to its original position by a first lateral movement, such that the displacement member is positioned below or above said weighing surface; 'movement in a plane parallel to the weighing surface and below or above the weighing surface, in a direction transversally across the weighing surface; zea second lateral movement to the original position of the displacement member.

Thus, the original. : position, may for example be in the plane of the weighing surface behind the items that are to be weighed, seen from the position of the receiving means for the items. From such a view, the : movement of the displacement member essentially is characterized by movement through the plane of the weighing surface towards the receiving means, thus pusing the weighed items into the receiving means. In one embodiment of the invention, the weighing apparatus is characterized by the first lateral movement comprising. movement to a position essentially below said weighing surface. As a consequence, after the delivery of weighed items into the receiving means, the displacement member moves vertically to a position below the plane of the weighing surface and back to its original position, thus allowing simultaneous loading of items and determination of their weight on the weighing surface.

In one embodiment, the displacement member has a width approximately equal to the width of said weighing surface. By such a design, the effective removal of all items from the weighing surface is materialized, and is in particular important for displacement of a plurality of relatively small items from the weighing surface.

However, in other embodiments, it is possible that the displacement member has different dimensions, in particular when the items to be displaced are relative large and a relatively small displacemnt member is sufficient to be effective. The

displacement member does not have to be comprised of a continuous contact surface with the items to be displaced. Rather, it is possible in particular embodiment of the invention that the displacement member is provided in a plurality of individual displacement members, which may or may not be part of a single overall structure with respect to the movement of the displacement member across the weighing surface.

In one preferred embodiment, the weighing surface comprises at least one aperture and the displacement member copmrises at least one bar member for movement along and through said at least one aperture. In another embodiment, the weighing surface comprises a plurality of apertures and wherein the displacement member comprises an equal number of plurality of bars for movement along and through said apertures. By such a design, the displacement member may be of the general shape of a"comb"or a"fork". Such a design of the displacement member has the advantage of providing effective displacement of items from the weighing surface, and convenient movement through the weighing surface, provided by the apertures in the surface, across a plane approximately parallel to the plane of the weighing surface, and back through the apertures in the weighing surface for displacement of subsequent items that have been positioned on the weighing surface and subsequently weighed.

The design of the displacement member of the invention can be varied to suit different applications.-In particular the design will depend on the nature of the weighing equipment being used and the nature of the production line of which the weighing equipment belongs. Thus, size constraints amongst other things are expected to be important for considering potential designs of the particular embodiments of the invention, while fulfilling the particlar characteristics defined in the above. Furthermore, the design of the displacement member can be varied while fulfilling the principle characteristics of the invention. In particular, various designs which include means for moving the displacement member within the plane of the weighing surface, above the plane or under the plane ; after displacement of the item or items that have been weighed from the weighing surface, are within the scope of the invention.

In one embodiment, the displacement member is comprised of a first arm, said arm being mounted at its proximal end on said motor, a second arm being mounted at the distal end of said first arm, and a plurality of bars mounted normally on said second arm. In another embodiment, the first arm, the second arm and the plurality of bars are provided in one continuous structure.

Loading of items onto the weighing surface of the weighing apparatus of the invention may conveniently be done by manual means. Thus, a construction or manufacturing line worker is typically capable of manually delivering up to about 100 items per minute. In such an operation, each cycle of the weighing

procedure takes about 0.6 seconds, which includes determination of the weight of the item or items placed on the weighing surface, displacement by the displacement member and manual loading of the weighing surface. Commercial static weighing means are capable of determining the weight of items in a fraction of a second, and the movement of the displacement member across the weighing surface for displacing the item or items that have been weighed can be made as fast as needed by means well known to those skilled in the art. A signal from the weighing means after the determination of the weight is complete can be used to trigger movement of the displacement means. Overall, the rate determining step of this mode of operation will therefore in principle be provided by the loading rate of the operator.

In alternative modes of operation, automatic delivery means, e. g. by a conveyor, are used to deliver items to the weighing surface. In such modes, the throughput of the weighing apparatus can be increased, but will however typically require a uniform distribution of items on the conveying means. Alternatively, a sensor which can detect the position of items on the conveying means can adjust the rate of delivery of items, e. g. by adjusting the rate of the conveyor.

In a second aspect, the present invention provides a method of operating a weighing apparatus, the method comprising the steps of conveying at least one item to be weighed onto a weighing surface; recording and storing the weight of each item to be weighed onto a data recorder ; removing weighed items from the weighing surface after their weight has been recorded by means of a displacement member; * delivering weighed items into a receiving means, wherein said displacement member comprises means for movement from a displacement position to an original position, after displacement of a first item or items from said weighing surface, without entering the space occupied by subsequent item or items to be weighed, after said item or items have been positioned on said weighing surface. By this method, it is possible to replace items that have been displaced from the weighing surface, while the displacement member moves back to its original position for displacement of subsequent item or items placed on the weighing surface.

In one embodiment, the removal of items from the weighing surface by means of said displacement member comprises the steps of

transversal movement from an original position across said weighing surface, thus essentially removing the weighed items from the weighing surface; 'movement of said displacement member to its original position by a first lateral movement, such that the displacement member is essentially positioned below or above said weighing surface; movement in a plane parallel to the weighing surface and below or above the weighing surface, in a direction transversally across the weighing surface; a second lateral movement to the original position of the displacement member.

In a preferred embodiment, the first lateral movement comprises movement to a position essentially below said weighing surface.

In another embodiment, the method involves the use of a weighing apparatus comprising a weighing surface which comprises a plurality of apertures wherein the displacement member comprises an equal number of plurality of bars for movement along and through said apertures. In such an embodiment, the displacement member may be of the general shape of a"comb."or a-"fork". Such a design of the displacement member has the advantage of providing effective displacement of items from the weighing surface ; and convenient movement through the weighing surface, provided by the apertures in the surface, across a plane approximately parallel to the plane of the weighing surface, and back through the apertures in the weighing surface for displacement of subsequent items that have been positioned on the weighing surface and subsequently weighed. Thus, in this embodiment, a convenient and dependable manner of displacing items from the weighing surface and moving the displacement out of the weighing surface via a convenient design.

Detailed description of the Invention In the following, a preferred embodiment of the invention will be described in further details with reference to the drawings in which: Figure la shows the weighing grid and the displacement or kick-off mechanism in an idle state, Figure 1b shows the weighing grid and the displacement or kick-off mechanism in a full forward or kick-off position, and Figure 2 shows the weighing grid and the weighing sensor.

A a weighing surface 1 comprising a plurality of apertures or slots 7 so as to be in the shape of a weighing grid is attached to a weighing sensor (i. e. a load cell) 2 as shown in figure 2. A displacement member 3 in the shape of a comb-like structure serves the role of a kick-off mechanism for items that are to be weighed on the weighing surface. The displacement member 3 is placed with both vertical 5 and horizontal 4 actuators underneath the weighing grid 1 so that its bars, in the shape of teeth, 6 can stick up through and slide along the slots 7 in the grid 1. In an idle state the comb 3 is in a full backward position as shown in figure la.

When an item enters the weighing grid (not shown) and a weighing signal has been processed, the comb is pushed forward by the horizontal actuators, kicking the item off the grid. At its full forward position (fig. Ib) the comb is pulled down by the vertical actuator 5 and at the same time a pull-back operation is performed by the horizontal actuators 4 to move the comb back to its horizontal starting position. Finally, to close the weighing circle the vertical actuator pushes the comb upwards to its idle state.

It should be appreciated that mechanisms for delivering items to be weighed to the weighing surface, as well as mechanisms for removal of items that are kicked off by the displacement member are well known in the art. Thus, a variety of manual and/or automatic means for feeding items to be weighed or removing items that have been weighed are possible and within the scope of different embodiments of the invention.

The core of the invention is to-select a different path for the kick-off mechanism to travel backwards than to travel forward. The backwards path lies underneath the weighing surface so that a weighing of a new item already entered on the weighing surface is not affected. A new weighing cycle can therefore be initiated before the kick-off mechanism has travelled back to its idle state, significantly increasing the throughput of such device.