WEIGHING DYNAMIC LOADS

Abstract: Apparatus for the weighing of successive loads by means of a weighing device (10) which provides an electrical signal representative of weight, in which the signal is examined to establish a weight reading according to a predetermined criterion (24). Establishment of a weight reading actuates latch means (25) to hold the weight display (17), and the signal is examined to establish a new load condition (26), whereupon the latch means (25) is reset to release the display (17).

Description: WEIGHING DYNAMIC LOADS TECHNICAL FIELD This invention relates to weighing apparatus of the kind particularly adapted for the weighing of loads which are successively applied to and removed from a weighing device and which may involve load fluctuations, such as for example in livestock weighing. BACKGROUND ART In the weighing of such loads it is known to provide a weighing platform provided with a number of load cells or weigh bars, the outputs of which are utilized to provide a displayed output indicative of the current weight. Appropriate damping is applied to the weight- indicating signal and the weight y noted when a stable reading is obtained. SUMMARY OF THE INVENTION The present invention seeks to provide an approach to the weighing of such loads with greater convenience and greater productivity, by providing a weighing system which automatically detects the change from a previous load to a new load while displaying and if required storing the previous weight, and which provides considerable choice of operating modes. In one broad form the invention resides in weighing apparatus comprising a measuring device providing a signal representative of a load, signal processing means responsive to said signal to arrive at, according to a predetermined first criterion, a weight value, display means displaying said value, latching means actuated by the establishment of said value maintaining said display of said value, means detecting, according to a predetermined second criterion, a new load condition, and latch resetting means responsive to said new load condition detecting means to reset said latch means. The detection of a new load condition may, for example, be provided by the detection of a reduction in the load to zero or to a value within a range of small load values (referred to as a "zero window"), or by the " detection of a weight increase of predetermined magnitude following the detection of zero or a zero window. In one of many alternatives, a new load condition may be established when the load falls to a predetermined fraction (for ^ example one half) of the latched displayed weight. The latter arrangement is particularly suited to. livestock weighing. Preferably the signal processing means includes damping means providing, when activated, a damped signal . derived from said load representative signal. Preferably also actuation of the latching means to "hold" the displayed weight value operates to modify the operation of the damping means to reduce the damping applied to the weight signal, in order that a zero or zero window condition or other new load condition, may quickly be sensed. BRIEF DESCRIPTION OF THE DRAWINGS In the drawings : Fig. 1 is a schematic illustration showing the main components of a weighing system according to an embodiment of the invention; and Fig. 2 schematically shows the relationship between functional units of the weight signal processing system in this embodiment. DESCRIPTION OF PREFERRED EMBODIMENT As shown in Fig. 1, the apparatus comprises a weighing device 10 of known kind providing a signal indicative of the instantaneous weight of an applied load. Such a device may, for example, comprise a conventional cattle weighing platform provided with load cells. A microcomputer 11 is provided, consisting conventionally of a microprocessor 12, read-only-memory. 13, random access memory 14, and peripheral " interface adaptor 15, under the control of a clock 16. The signal from the weighing device 10 is applied to the PIA 15, for examination under the control of the system software resident in the ROM 13. Particular software solutions to provide the functions which will be described below are within the competence of those skilled in the art of microprocessor control, and will not be detailed in this specification. It will also be appreciated that the functions described may be achieved by "hard wired" devices, and such are within the scope of the present invention. Connected to the PIA device 15 is a digital display device 17, which provides weight readings and an indication of the status of the reading as will be described below. A switch 18, which may be provided internally or at the back of the apparatus, enables the supplier or user to set the resolution mode, determining the weight increments which will be shown by the display 17. Similarly, a switch 19 enables the type of hold function to be chosen, these functions being described below. Where a manual hold or hold release function may be required, the device provides a hold release button 20, accessible to the operator, the operation of which is described in detail below. Also accessible to the operator is a "tare" switch 21, the known function of which is to re-set the zero load reading of the apparatus. Provision is also made at 27 for the connection of a printer or- other peripheral devices. In operation, the signal from the weighing device 10 is examined under the control of the system software to provide a functional operation which will be described with the aid of Fig. 2, which shows the functions essential to this embodiment of the invention, in a schematic way. The weighing device 10 employed in the practice of the present invention may comprise a group of load cells or weigh bars employing electrical strain gauges, and an output device providing a signal which representative of the weight measured. The signal from the weighing device 10 is subjected to damping by means 23, in this embodiment being a software function, and the damped signal is examined at 24 to locate a stable or "no motion" reading. In the preferred embodiment the criterion for a stable reading consists of the occurrence of successive readings which are within a predetermined tolerance. Other criteria may of course be employed as is well known in the art. Whatever criterion may be adopted for the existence of a stable reading, it is preferred that the degree of damping applied to the signal by the damping means 23, be progressive, so that as the signal from the device 10 more closely approaches stability the degree of damping increases. Upon the determination of a stable reading, the display 17 is locked by hold means 25 at the indicated weight reading and preferably an additional indicia, such as a + sign, is activated at the display to indicate the latched status of this reading. At the same time, the damping effectively applied by the damping means 23 is reduced, so the system may respond more quickly to a change in weight. At this time also, the stable weight reading may be stored and/or printed. The weight signal is now monitored by "new load" function 26 for the occurrence of a weight signal which satisfies the criterion which establishes the commencement of the next weight-reading cycle. This criterion may be the reduction of the indicated weight to zero or to a reading within a zero window, followed by a positive-going reading passing out of the zero window. Where a faster response may be desirable, a weight reduction to some fraction, say 1/2, of the stable weight may be preferable as the trigger for the next weighing cycle by the function 26, while in fleece weighing, a predetermined percentage increase or decrease may be employed, enabling the weighing of belly wool, and then fleece, without removal of the belly wool. 5 In any case, once the satisfaction of a criterion for a new weighing cycle is established by the function 26, the display is unlatched by releasing the hold function 25 * This automatic sensing of a new load by the satisfaction of a chosen criterion provides a significant 12 advance in the art of weighing successively applied loads, in enabling greatly increased throughput, as no operator intervention is required. Thus for example, in cattle weighing where the new • t load s.ensing criterion preferably employed is the zero 15 load or zero window mode, the animal may be removed from the scales without losing the weight reading as this remains on hold until, following the removal of the weighed animal, the next animal is placed on to the scale. This enables reliable single operator cattle weighing. 20 in the case of sheep weighing with automatic drafting, the preferred new load criterion is a fractional decrease in the load. Once a stable reading is achieved, the next load can be applied immediately the requisite fractional decrease is detected, this being detected 25 quickly due to the damping having been reduced upon latching of the display. If desired, the introduction of a new load to the weighing device, and the exit of the previous load therefrom can automatically be controlled in response to the detection of a stable weight signal by the means 24. In this way the weight measurement is unaffected by the ability of sheep to defeat the drafting equipment and for example, to enter the scales before the departure of the weighed animal. The display latch condition is used to control the operation of the drafting equipment, and a throughput of sheep can be achieved which is far superior to that obtained in the prior art, with no errors arising from the behaviour of the sheep. The weight signal which is monitored for the establishment of the new load condition may be derived from any suitable stage of signal processing within the device. Various degrees of manual override may be incorporated in a system such as that described. For example, by means of the hold function switch 19 the- release of the latching applied to the stable reading may be made manual, requiring the actuation by the operator of the latch release button 20. Similarly, there may be provided a mode of operation in which latching and latch release may only be achieved manually. A "verify" function is provided by the switch 20, in addition to its reset function already described. If the apparatus has been set to the manual hold mode of operation by means of the switch 19, operation of the switch 20 once will set the hold means 25 to its latching condition, while operation of switch 20 a second time will reset the hold function. More importantly, however, with the apparatus in its automatic hold and release mode, actuation of the switch 20 will simultaneously reset the hold means 25. As the damping means 23 has already been set to its loose level of damping, this enables the operator to verify the weight reading.

Claims: CLAIMS : 1. Weighing apparatus comprising a measuring device providing a signal representative of a load, signal processing means responsive to said signal to arrive at, according to a predetermined first criterion, a weight value, display means displaying said value, latching means actuated by the establishment of said value maintaining said display of said value, means detecting, according to a predetermined second criterion, a new load condition, and latch resetting means responsive to said new load condition detecting means to reset said latch means. 2. Apparatus according to claim 1 wherein said signal processing means includes damping means providing, when activated, a damped signal derived from said- load representative signal. 3. Weighing apparatus according to claim 2 further comprising means modifying the operation of said damping means to reduce the damping applied thereby upon the actuation of said latching means. 4. Weighing apparatus according to claim 3 further comprising manually operable means actuating said latch resetting means. 5. Weighing apparatus according to claim 1 wherein said second criterion comprises the reduction of the weight indicated by said signal to a weight within a predetermined range below said weight value,- followed by an increase in said weight indicated by said signal to a value greater than the maximum weight within said range. 6. Weighing apparatus according to claim 1 wherein said second criterion comprises a predetermined reduction in the weight indicated by said signal. 7. Weighing apparatus according to claim 1 wherein said second criterion comprises an increase in the weight indicated by said signal to a weight which exceeds to a predetermined extent said stable weight value. 8. Weighing apparatus according to claim 1 comprising means associated with said display means indicating the actuated condition of said latching means.

Inventors: KELLENBACH ARTHUR, KELLENBACH, ARTHUR
Applicants: KELLENBACH ARTHUR, KELLENBACH, ARTHUR
Application year: 1986
Main classification: G01G23
IPC codes: G01G17, G01G23