GB1574495A - Weight computing system - Google Patents

Description

(54) WEIGHT COMPUTING SYSTEM (71) We, HI-SPEED CHECKWEIGHER COMPANY INC., a corporation organized and existing under the laws of the State of New York, United State of America, located at 605 West State Street, Ithaca, State of New York, United States of America, do hereby declare the invention for which we pray that a Patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a high speed weight computing system and to a method of weighing a succession of articles.

Electronic techniques have been applied to the weighing art. Electronic scale and weighing systems have been developed which provide a relatively rapid readout in digital format without the use of springs and similar mechanical devices. A particularly useful system involves the use of a load cell or similar transducer which provides an analog voltage or signal which is proportional to the weight of an unknown load to a high degree of linearity. Amplification and analog-to-digital conversion is employed to provide a digital output signal corresponding to the weight of the load.

Systems of this type have been developed commercially which are capable of displaying the weight of a load accurately to the nearest hundredth of a pound within several seconds.

Weight-price labelling systems have also been developed using the above format in conjunction with commercially available solid state microprocessors in which the net weight of an article is computed by subtracting a set tare weight from the measured gross weight of an article and then computing the article price by multiplying the net weight by the price per unit weight. In these systems, a keyboard is employed to enter the price per unit weight into the microprocessor and also to enter the tare weight data. Optionally, the tare weight data may be entered directly from the scale by loading a representative emtpy article container on the scale, the system being provided internally with circuitry which allows entry of this measurement as the set tare weight data when this option is exercised.

In conjunction with visual display of the set tare weight, net weight, price per unit weight and computed article cost, a label printing device is operated which prints the desired information on a label for application to the article package.

Systems of this latter type have found wide applicability in retail outlets such as supermarkets and the like, and are likely to encounter increasing demand for various reasons.

However, such systems require somphisti cated and expensive electronic circuitry in order to attain and maintain the accuracy which is inherent with present electronic weighing transducers. For example, although a state of the art load cell or similar transducer will be highly linear over a particular load range and therefore is capable of yielding weight readings of high accuracy within that range, normal electronic drift in the equipment which processes the transducers signal may well intro duce error which substantially reduces the overall accuracy. Thus, substantial effort has been expended in order to establish a stable " zero " reference from which the weight measurements are taken.Obviously, if stable " zero" i 5 not achieved, the measured gross weight which provides the basis for all computations will correspondingly be in error.

According to one aspect of the present invention there is provided a high speed weight computing system which includes in combination: weight-sensitive means for producing an output signal in response to weight acting thereon; conveyor means for conveying articles along a path passing over said weightsensitive means and including control means for transiently depositing said articles on said weight-sensitive means; sensor means for actuating said control means transiently to deposit an article on said weight-sensitive means; and computer means interfaced with said sensor means and with said weight-sensitive means for computing the gross weight of an article based upon the difference in outputs of said weight-sensitive means when an article is transiently deposited on the weight-sensitive means and when the article is not on the weight-sensitive means.

According to another aspect of the present invention there is provided a method of weighing a succession of articles which comprises the steps of: (a) effecting movement of a succession of articles along a horizontal path to and from a position above a weighing platform; and (b) sensing the presence of each article as it moves to the weighing station and effecting a cycle of operations in response thereto, said cycle of operation comprising: (1) depositing said article in a lowered, at rest position on said platform, (2) raising the article from the platform to effect its movement from said position above the platform, (3) measuring the article-laden weight of said platform while the article is in its rest position; (c) measuring the unladen weight of said platform separately with respect to each measurement of cycle step (3); and (d) automatically computing the weight of the article from the measurement of cycle step (3) and step (c).

The present invention will now be described in more detail, by way of example, with reference to the accompanying drawings in which: - Figure 1 is a perspective view of the machine according to the invention and illustrating in phantom lines the infeed and discharge conveyors which may be associated therewith; Figure 2 is an enlarged vertical section taken longitudinally through the weighing station and showing certain details of construction with respect to the mechanical aspects of the device; Figure 3 is a view on enlarged scale taken transversely through the weighing station and showing the relative disposition of component parts prior to lowering of the article; Figure 4 is a view similar to Figure 3 but illustrating the disposition of component parts after the article has been lowered onto the scale platform;; Figure 5 is a face view showing a portion of the control and display of the machine; Figure 6A taken in conjunction with Figures 6B and 6C cumulatively illustrate the schematic arrangements of the various components of the electrical system of the machine; Figure 7 is a detailed circuit illustration of the input expander of Figure 6A; Figure 8 is a detailed circuit illustrating the load cell circuit board of Figure 6B; Figure 9 is a detailed circuit illustrating the analog-to-digital conversion board of Figure 6B; and Figures 10-14 are logic flow diagrams illustrating the manner in which the central processing unit is programmed.

Reference is had more particularly at this time to Figures 1-5 inclusive which show various details of the mechanical aspects of the system with which the present invention is associated. The mechanical aspects are disclosed in detail in United States Patent No. 3 955665 is incorporated herein by reference thereto.

Figure 1 illustrates the overall system and will be seen to include the printing and labeling assembly generally indicated by the reference character 10, the weighing station indicated generally by the reference character 12 to one side of which is the infeed conveyor section 14 and to the other side of which disposed the outfeed conveyor system 16. The conveyor section 14 receives articles from a delivery conveyor indicated generally by the reference character 18 and articles are removed from the system by the discharge conveyor mechanism 20. The operator's side of the system embodies a control console indicated generally by the reference character 22 which includes certain control buttons and control lights as well as a keyboard and, in addition, a display section all as described hereinafter.

Figure 2 illustrates the basic principle of the mechanical aspects of the weighing station and as shown, there is provided a weighing platform assembly indicated generally by the reference character 24 which acts upon a suitable load-responsive transducer housed in the stationary support device 26. The transducer may be a commerically available strain guage device which is of highly linear nature within a specified weight range and which is characterized by requiring very little total movement of the weighing platform 24. An endless chain or conveyor system comprising a plurality of lengths of endless chain or the like 28 is trained over a plurality of fixed idlers indicated by the reference characters 30, 32, 34, 36, 38, 40 and 41 and over the drive sprocket 42 as is shown.

An essentially constant velocity input drive is imparted to the chains or other endless conveyor members by the drive sprocket 42. The weighing station which is represented by the section 44 is characterized by the two standards or rackets 46 and 48 which are carried by the vertically slidable posts 50 and 52 respectively. These posts are slidably guided in the fixed support members 54, 56, 58 and 60 and the bottom of each post 50 and 52 is provided with a cam follower in the form of a roller such as those indicated by the reference character 62. The bracket 46 carries a pair of idler rollers 64 and 66 and the bracket 48 carries an idler roller 68.A double acting pneumatic cylinder or the like indicated generally by the reference character 70 is provided with piston rod portions 72 and 74 which are connected to the slidable cam blocks 76 and 78 and when the device 70 is actuated, the cam blocks 76 and 78 are translated to the left in Figure 2 so that the followers 62, under the action of the compression springs 84 and 86, will remain in engagement with inclined ramp portions 80 and 82 of the blocks 76, 78 consequently to cause lowering of the brackets 46 and 48. The effect of this can be seen in Figures 3 and 4. In Figure 3, the normal disposition of the endless conveyor portions 88 in the weighing station section 44 are shown in their normally disposed elevated positions whereby to support an article A in elevated position above the rails or plates 90 which form the weighing platform 24 proper.Figure 4, on the other hand, shows the conveyor sections 88 in their lowered positions corresponding to the lowered positions of the brackets 46 and 48. A characteristic feature of the system thus far described is that as the conveyor sections 88 are lowered, the action of the three idler 64, 66 and 68 is such that although the infeed and outfeed sections 92 and 94 of the endless conveyor continue their constant velocity movement, the section 88 are transiently affected by a deceleration component due to the lowering of such sections 88. The inclination of the ramps 80, 82 and of the translational movement of the blocks 76 and 78 can be so adjusted that an article A can be decelerated correspondingly by this action.

Two sensor devices as indicated in Figure 1 by the reference characters 100 and 102 are retroreflective photosensors and have associated reflectors 104 and 106.

The sensors are provided to control the timing of the system with respect to the movement of the incoming articles A. As can be seen in Figure 2, when the beam of the first sensor 100 is broken, as the article enters onto the conveyor sections 88 from the infeed section 92, two effects occur. First, the output signal of the unladen scale platform 24 will be sampled and the mechanism 70 will be actuated whereby to lower the sections 88 and deposit the article A centrally upon the weighing platform 24. The cycle then continues with the raising of the conveyor sections 88 and a second sampling before the article is engaged by the conveyor; and as the article is transferred to the discharge or outfeed section 94, it breaks the beam of the second sensor 102 which commences the price label application to the corresponding article.Both of the sensors 100 and 102 are movable longitudinally along the system so as to be adjustable in precise position to achieve the proper timing actions when depositing the articles on the weighing platform and in positioning them properly in relation to the label applicator 104 as illustrated in Figure 1.

An important characteristic of the present invention will now be apparent, namely, that two output signals from the weighing transducer are obtained for each article under consideration, one of these signals indicating the unladen weight of the scale platform and the second indicating the laden weight of the scale platform. This is an important consideration inasmuch as it liberates the system from the serious constraint of having to provide a stable "zero" for the system. As previously explained, and as will be evident, prior art devices which utilize only a signal when the scale is laden must provide means which positively assures that the unladen output signal will be "zero" and will remain so during operation.Whereas such a stabilized "zero" can be achieved by utilization of complex electronic circuitry, it is not only expensive to achieve this but it also does not accommodate for gross product build-up on the scale platform which may easily occur. According to the present invention, the system is immune from product build-up on the scale platform (except in the rare instance in which such build-up should occur between readings) and as noted the constraint of providing for a stable "zero" is eliminated.

Referring now more particularly to Figure 5, the operator control panel is illustrated therein and is designated generally by the reference character 110 which, with reference to Figure 1 will be seen to occupy the right-hand portion of the machine.

Three regions containing illuminated or back-lighted push buttons are positioned on the front panel as indicated generally by the reference characters 112, 114 and 116 and, in addition, a keyboard 118 is provided. Further, a display region 120 is provided which contains four areas of display as indicated by the reference characters 122, 124, 126 and 128. The push button switches individually are indicated by reference characters 130, 132, 134 and 140 in Figures 6A, 6B and 6C, and the corresponding buttons of these switches are indicated by like reference characters in Figure 5.

The machine is powered up by depressing the switch button 136, which causes the back-lighting bulb (not shown) to be illuminated. The remaining back-lighting bulbs are illustrated in Figure 6C and are designated therein by the reference characters 129, 131, 133, 135, 139, 141 and 142. The scale error bulb 139 illuminates, for example, when the tare weight entry exceeds the measured weight of the article. The bulb 142 back-lights the "label" section of the button of the switch 140 when this switch is open whereas the bulb 141 backlights the "disable" section when the switch 140 is closed. The bulb 129 backlights the "process enable" section of the button of the switch 130 when the central processing unit (CPU) 152 shown in Fig. 6a commands whereas the bulb 131 backlights the "hold" section when the CPU commands. The bulb 133 back-lights the button of the switch 132.

Reference is had to Figures 6A, 6B and 6C which are a composite illustrating various circuit boards and their functional interrelationships and electrical interconnections constituting the entire system according to the invention. Of the circuit boards illustrated in these three Figures, the boards 150 and 152 are commercially available items as indicated in Figure 6A.

Figures 6A, 6B and 6C do not show the labeler control circuitry, same constituting no part of the present invention. However, the outputs to the labeler control circuit is provided by the conductor 154 indicated in Figure 6C. The output which controls the conveyor dropping/lifting device 70 in Figure 2 is provided at the conductor 156, specifically the output at 156 is applied to a solid state relay controlling the pressurized air supply valve for the device 70.

The keyboard 118 is a commercially available device and may be of any conventional form utilizing a set of normally open momentary contact switches each of which is grounded when the corresponding button is depressed. The input lines to the keyboard are provided in parallel with the switches 130, 132 and 134 as illustrated in Figure 6C. The grounded outputs from the keyboard 118 and/or the switches 130, 132 and 134 are applied as inputs to the data selector 158 and a single output appears at the conductor 160 according to the code present on the four input lines 162, the conductor 160 being applied to the circuit board 152 shown in Figure 6A. The conductors 162 are the select code lines which determine which of the inputs is applied to the output conductor 160 and the code present at the lines 162 is determined by the output port 164 of the central processing unit 152.

The remainder of the multifunction board 166 consists essentially of the 75452 dual peripheral drivers such as the set consisting of the gates 168, 170, 172 and 174 which are contained in two integrated circuit chips. Additionally, the board 166 includes a power on reset circuit of conventional form (not shown) which applies a reset state for a predetermined time on the conductor 176 after application of power and this signal is applied to the central processing unit (CPU) board 152 as indicated in Figure 6A.

The input expander circuit board 180 is provided to increase the number of input ports to the central processing board 152.

Specifically, the X and Y inputs as illustrated in Figure 6A are provided and they are connected to thumb wheel switches (not shown) which merely set a binary coded decimal (BCD) number to be read as an input by the central processing unit to determine certain timing functions of the system. The X input number is used to establish a timing function associated with breaking of the sensor 100 beam.

As soon as the beam of the sensor 100 is broken, the "out 3" port of the CPU board 152 (Figure 6A) causes the output conductor 156 from the multifunction board 166 (Figure 6C) to provide a signal which initiates lowering of the incoming article onto the scale platform and simultaneously interrogates the analog-to-digital (A/D) converter board 184 (Figure 6B) over the conductor 182. Thereafter, the CPU sequentially interrogates the input expander board 180 to input the preset BCD number at the X input and interrogates the board 180 to input the preset BCD number at the Y input. The number read by the CPU from the X input determines a first time delay which is to prevail until the lifting mechanism signal at the conductor 156 is restored to its initial condition and the number read by the CPU from the Y input determines a second time delay before the second reading is taken from the A/D converter board 184.

As noted, the A/D board 184 is interrogated when the lifting mechanism command to "drop" is applied at the conductor 156 and since the article is not instantaneously lowered onto the scale platform, this first reading from the A/D board is the unladen scale weight. The first time delay is so chosen by the present number at the X input that cessation of the "drop" command signal occurs only at such time as allows the incoming article at least momentarily to be lowered fully onto the scale platform and the second time delay is so chosen by the preset number at the Y input that the second interrogation of the A/D board 184 occurs while the article is so lowered fully. In this way, the second reading from the A/D board will be the laden scale reading.

Figure 7 is a schematic of the input expander circuit board 180 shown in Figure 6A and will be seen to include two integrated circuits 190 and 192 and the integrated circuit 194, the latter functioning primarily as a buffer. The binary coded decimal (BCD) number present on the lines 196, 198, 200 and 202 in conjunction with the enabling signal on the conductor 204 selects either the X input or the Y input, the former consisting of the four conductors 206, 208, 210 and 212 and the latter consisting of the input at the four conductors 214, 216, 218 and 220. This selected input will appear on the output lines 222, 224, 226 and 228 to the CPU board 152 as shown.

The load cell amplifier and filter board 230 of Figure 6B is illustrated in detail in Figure 8. The transducer or load cell device indicated generally by the reference character 232 is a strain gauge load cell of conventional construction. The circuit of Figure 8 employs three integrated circuits of the type LM308AH manufactured by National Semiconductors and indicated respectively by the reference characters 234, 236 and 238. The circuit 234 receives the output of the load cell 232 over the conductors 240 and 242 and performs an amplification with a gain of 62.5 whereas the two circuits 236 and 238 are connected as unity gain amplifiers acting as active low pass filters with a cut off frequency of 20Hz. The output of the circuit of Figure 8 is at the conductor 244 wherein the change of the voltage output on the conductor 244 is proportional to the change of load on the scale.The purpose of this high gain circuit will be apparent presently.

The analog-to-digital converter board 184 is illustrated in Figure 9 and contains a commercially available A/D module 246 which is an ADC 1100 manufactured by Analog Devices. The input conductor 244 from the circuit of Figure 8 is applied through the voltage divider circuit constituted by the potentiometer 248 and resistor 250 so as to provide gain control of the input signal to the circuit 246 from the circuit of Figure 8.

Ordinarily, the input to the converter 184 would be adjusted to produce a count change output of one hundred counts in response to a scale weight input change of one pound, thereby providing a count output which may be displayed to the hundredth of a pound. However, it is well known that there is an inherent quantization uncertainty of +1/2 LSB (least significant bit) associated with any A/D system.

In the present invention, since the results of two A/D conversions are being subtracted (laden weight minus unladen weight) the resulting resolution is + 1 LSB.

In order to reduce this uncertainty, the input range to the A/D circuit, and consequently its output range, is effectively expanded and subsequent to the subtraction of the outputs, the resulting difference is divided by the expansion factor. In this way, it can be shown that the resolution uncertainty is reduced to 1 /nth of one hundredth of a pound where n is the aforesaid factor. In a specific embodiment, this factor is four so that the uncertainty becomes .010 lob. - .0025 lb. Specifically, 4 whereas the A/D converter 246 requires an input change of 10 millivolts to produce an output change of 100 counts, the potentiometer 248 is set so that for a change of weight of one pound on the scale platform, there will be a change of 40 millivolts at the input to the circuit 246, causing an output count change of 400 counts.Thus, the aforesaid expanding factor n is 4.

As shown in Figure 9, the sensor 100 is connected to the NE555 chip 254 configured as an inverter and functioning to produce in conjunction with the circuit 256 an output pulse as indicated at reference character 258 whose duration is determined by the setting of a potentiometer 260 in conjunction with a capacitor 262 to provide a lock out against double interrogation when the light beam impinging on the sensor 100 is broken more than one time by an entering package. The output signal on the conductor 264 is applied to the input port 265 of the CPU 152. The data selectors 266 and 268 are of conventional construction as indicated in Figure 9 and operate in conjunction with the input lines 270 and 272 from the CPU which are the lower two bits of the port 164.This selects the binary coded decimal (BCD) digits in succession from the circuit 246 on command from the CPU and in sequence thereby to appear at the output lines 274, 276, 278 and 280 which are applied back to the CPU 152.

Two display modules as are shown in Figure 6B as are indicated by reference characters 300 and 306 there, and provided for providing the display at 120 in Figure 5. Specifically the display module 300 provides the display for the net package weight at 122 and the package price at 124. The display at 122 is under command of the CPU 152 in response to the two weighing signals and the computation effected in response thereto and the display at 124 is the result of the computation of the package price based upon the net package weight as computed by the computer. The two displays at 126 and 128 are controlled by the module 306 and are set by keyboard entry at 118 or, optionally, the tare weight may be set by passing the product container over the scale platform to take its weight.Once the set tare button 132 is depressed, the tare entered into the computer memory may be accepted either from the keyboard 118 or by passing an empty package over the scale mechanism.

If the tare is entered from the scale device is rounded if necessary and, progressing through the line E to Figure 13, the result is latched into the net weight display, provision is made to turn off the scale error light, the result and the price per pound are entered into the print line, the net the entry will be only to the nearest one hundredth of a pound and the last digit of the display will be zero. Likewise, the button 134 is depressed to enter the price per pound from the keyboard 118, which entry is displayed at 128.

The printer interface board 308 is constructed to be compatible with the particular printer utilized in the labeling section of the machine, same forming no part of the present invention. However, the output port 310 of the CPU board 152 provides the input control signals for the printer. The binary coded decimal (BCD) numbers on the output lines 311 of the printer interface correspond to the character in position to be printed and are applied to the input port 312.

The logic flow diagrams of Figures 10-14 serve to illustrate the manner in which the processing assembly is to be programmed in order to perform the various operations described hereinabove. Although these Figures are believed largely self-explanatory, a brief description will be given.

Starting with Figure 10, when the device is powered up, various initial values are set up as indicated and the state of label/ enable button is read and stored. Since at this time beginning at the position "start" this will be the first time through, the internal mode bit is set to =1 ("hold") and the "hold" section of the switch button 130 is back-lighted. It is assumed at this time that the tare button has not been depressed and so the logic flows through the branch C to the corresponding branch of Figure 11. It will be also assumed at this time that the price per pound button has not been pushed and so the lamp test button "LT" which is the key at the lower right-hand corner of the register 118 in Figure 5 is interrogated.Assuming that this lamp test button is depressed prior to other operations, it will be seen from Figure 11 that all lights are lit and "eights" are latched into the display latches and this condition prevails so long as the lamp test button is depressed.

When it is released, the displays and lights are restored to their initial condition. This initial test of course allows checking of all lights and displays. At this time, the logic cycles back to "start" of Figure 10 and since this now is not the first time through, the process enable/hold switch is first interrogated and assuming at this time that this button is not pressed, the internal mode bit will be checked which, as aforesaid is set to =1 ("hold"). Assuming now that the tare button is being pushed, the logic flow will pause and wait for release of the button. The "set tare " switch button 132 will be back-lit and the tare display will be filled with E's.If a keyboard button is not pressed, provision is made for accepting tare entry from the scale which is detected by the scale eye which, if broken, causes the package to be weighed and if this weight is not greater than .999 pounds, the logic will cycle through branch B to Figure 11. This interrogation of the weight is provided to prevent a tare setting greater than .999 pounds, since it is not contemplated in the specific embodiment that the tare weight will ever be set to such a high value. Thus, if the tare weight is greater than .999 pounds, the scale error display button 138 will be back-lit.If, on the other hand, the tare weight is not excessive, the logic cycles through the line B to the corresponding portion of Figure 11 wherein the measured weight is moved to the tare display and the "set tare " and the " scale error" lights are turned off and, the measured weight is moved to the tare store section of the RANDOM ACCESS MEMORY (RAM) and the cycle goes back to " start If, on the other hand, the tare button has been pushed and a keyboard button is pressed, the corresponding digit is moved to the tare display register, the register scanned and the display latch is set accordingly and when the next keyboard button is pressed as shown at the line A at the bottom of Figure 10, the logic continues to the corresponding line A in Figure 11, the new digit being moved to the tare display register which is scanned and the display latches set accordingly. The third keyboard button entry for tare is then made and the three digits are then moved to the tare storage section of the RAM as described hereinabove, the "set tare" light and " scale error" light are turned off and the cycle goes back to "start" in Figure 10.

From start, if the "set tare" button is now not depressed, the logic will cycle again through the line C in Figure 10 to the corresponding line in Figure 11 and if now the price per pound button is depressed, E's will be loaded into the price per pound display and the switch button 134 will be back-lit. Then three characters are obtained from the keyboard and written into the display latches, in a manner similar to the entry of three tare digits as above described. The "set price/lb" light is turned off and the logic cycles back to "start" in Figure 10.

If now the momentary switch button 130 is depressed, the internal representation "hold" is terminated and the logic will flow to the line D in Figure 10 to flow to "enable" in Figure 12. If there is a new package on the scale, the read scale subroutine of Figure 14 is performd and if neither reading is over range, the difference is divided by four, the tare entry is subtracted from the result and its polarity checked.Since in the specific embodiment disclosed herein it is not intended to accommodate packages greater than 8 pounds, a check is made on the result and if it is within the proper range, the result weight is multiplied by the price per pound the product is rounded and is latched into the total price display, the product is moved to the print line with suppression of the leading zeros and if the machine is in the label mode, the print line is printed on the bale and the labeler is signaled to advance a label for application to the package and the cycle goes back to " start " in Figure 10.

The weighing subroutine of Figure 14 serves to illustrate further the timing provided by the X and Y inputs mentioned previously. As will be seen from Figure 14, the read scale or weighing subroutine drops the lifters 88 and starts the analog-todigital converter. After the time determined by the setting of the X input thumb switches, the analog-to-digital converter is interrogated and if it is ready, its output is stored in RAM location 50, any overrange being effective to produce an error exit.

Thereafter, the lifters are initiated in their lifting cycle and the time set by the Y input thumb switches determines the delay until the second interrogation of the A/D unit, the A/D output is stored in RAM location 60. Next, the reading stored in RAM location 50 is substracted from the reading stored in the RAM location 60 and the result is placed in RAM location 70. It will be appreciated that the reading stored in RAM location 50 is the unladen scale reading whereas the reading which is stored in RAM location 60 is the laden scale reading. If there is no error in polarity or in magnitude, the flow of logic exits the subroutine to resume after the point where the subroutine was invoked.

As has been noted hereinabove, two weight determinations are made for each package or article being processed, one weight reading corresponding to the unladen platform and the other corresponding to the laden platform. In this fashion, the unladen platform or "zero" reading may float without introducing error. The zero " level corresponding to the unladen platform is initially adjusted to some offset value by means of the potentiometer PT in Figure 8.

WHAT WE CLAIM IS: - 1. A high speed weight computing system including in combination: weight-sensitive means for producing an output signal in response to weight acting thereon; conveyor means for conveying articles along a path passing over said weightsensitive means and including control means for transiently depositing said articles on said weight-sensitive means; sensor means for actuating said control means transiently to deposit an article on said weight-sensitive means; and computer means interfaced with said sensor means and with said weight-sensitive means for computing the gross weight of an article based upon the difference in outputs of said weight-sensitive means when an article is transiently deposited on the weight-sensitive means and when the article is not on the weight-sensitive means.

2. A high speed weight computing system as claimed in claim 1 further including a keyboard interfaced with said computer means, control switch means for entering tare weight data from said keyboard into said computer means, and display means interfaced with said computer means for displaying net weight of an article based upon said computer gross weight less said tare weight data.

3. In a high speed weight computing system as claimed in claim 2 further including control switch means for entering price per unit weight data from said keyboard into said computer means, said display means also displaying article price based upon the computer net weight times said price per unit weight data.

4. A high speed weigh computing system as claimed in any one of claims 1 to 3 in which the weight sensitive means includes a weighing platform and in which the conveyor means includes a horizontal portion overlying said weighing platform, drive means for effecting continuous

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. tare" light and " scale error" light are turned off and the cycle goes back to "start" in Figure 10. From start, if the "set tare" button is now not depressed, the logic will cycle again through the line C in Figure 10 to the corresponding line in Figure 11 and if now the price per pound button is depressed, E's will be loaded into the price per pound display and the switch button 134 will be back-lit. Then three characters are obtained from the keyboard and written into the display latches, in a manner similar to the entry of three tare digits as above described. The "set price/lb" light is turned off and the logic cycles back to "start" in Figure 10. If now the momentary switch button 130 is depressed, the internal representation "hold" is terminated and the logic will flow to the line D in Figure 10 to flow to "enable" in Figure 12. If there is a new package on the scale, the read scale subroutine of Figure 14 is performd and if neither reading is over range, the difference is divided by four, the tare entry is subtracted from the result and its polarity checked.Since in the specific embodiment disclosed herein it is not intended to accommodate packages greater than 8 pounds, a check is made on the result and if it is within the proper range, the result weight is multiplied by the price per pound the product is rounded and is latched into the total price display, the product is moved to the print line with suppression of the leading zeros and if the machine is in the label mode, the print line is printed on the bale and the labeler is signaled to advance a label for application to the package and the cycle goes back to " start " in Figure 10. The weighing subroutine of Figure 14 serves to illustrate further the timing provided by the X and Y inputs mentioned previously. As will be seen from Figure 14, the read scale or weighing subroutine drops the lifters 88 and starts the analog-todigital converter. After the time determined by the setting of the X input thumb switches, the analog-to-digital converter is interrogated and if it is ready, its output is stored in RAM location 50, any overrange being effective to produce an error exit. Thereafter, the lifters are initiated in their lifting cycle and the time set by the Y input thumb switches determines the delay until the second interrogation of the A/D unit, the A/D output is stored in RAM location 60. Next, the reading stored in RAM location 50 is substracted from the reading stored in the RAM location 60 and the result is placed in RAM location 70. It will be appreciated that the reading stored in RAM location 50 is the unladen scale reading whereas the reading which is stored in RAM location 60 is the laden scale reading. If there is no error in polarity or in magnitude, the flow of logic exits the subroutine to resume after the point where the subroutine was invoked. As has been noted hereinabove, two weight determinations are made for each package or article being processed, one weight reading corresponding to the unladen platform and the other corresponding to the laden platform. In this fashion, the unladen platform or "zero" reading may float without introducing error. The zero " level corresponding to the unladen platform is initially adjusted to some offset value by means of the potentiometer PT in Figure 8. WHAT WE CLAIM IS: -

1. A high speed weight computing system including in combination: weight-sensitive means for producing an output signal in response to weight acting thereon; conveyor means for conveying articles along a path passing over said weightsensitive means and including control means for transiently depositing said articles on said weight-sensitive means; sensor means for actuating said control means transiently to deposit an article on said weight-sensitive means; and computer means interfaced with said sensor means and with said weight-sensitive means for computing the gross weight of an article based upon the difference in outputs of said weight-sensitive means when an article is transiently deposited on the weight-sensitive means and when the article is not on the weight-sensitive means.

2. A high speed weight computing system as claimed in claim 1 further including a keyboard interfaced with said computer means, control switch means for entering tare weight data from said keyboard into said computer means, and display means interfaced with said computer means for displaying net weight of an article based upon said computer gross weight less said tare weight data.

3. In a high speed weight computing system as claimed in claim 2 further including control switch means for entering price per unit weight data from said keyboard into said computer means, said display means also displaying article price based upon the computer net weight times said price per unit weight data.

4. A high speed weigh computing system as claimed in any one of claims 1 to 3 in which the weight sensitive means includes a weighing platform and in which the conveyor means includes a horizontal portion overlying said weighing platform, drive means for effecting continuous

motion of said conveyor means, and actuator means for lowering and then raising said horizontal portion to cause each article transiently to rest upon said weighing platform.

5. A high speed weight computing system as claimed in claim 4 in which said actuator means causes deceleration of each article as it is lowered to its rest position on the weighing platform.

6. A method of weighing a succession of articles which comprises the steps of: (a) effecting movement of a succession of articles along a horizontal path to and from a position above a weighing platform; and (b) sensing the presence of each article as it moves to the weighing station and effecting a cycle of operations in response thereto, said cycle of operations comprising: (1) depositing said article in a lowered, at rest position on said platform, (2) raising the article from the platform to effect its movement from said position above the platform, (3) measuring the article-laden weight of said platform while the article is in its rest position; (c) measuring the unladen weight of said platform separately with respect to each measurement of cycle step (3); and (d) automatically computing the weight of the article from the measurement of cycle step (3) and step (c).

7. A method as claimed in claim 6 wherein each article is decelerated as it is lowered to its rest position on the platform.

8. A high speed weight computing system substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

9. A method of weighing a succession of articles substantially as hereinbefore described with reference to and as shown in the accompanying drawings.