Patent Description:
Conveyor belts are often used to convey products through weighing stations such as checkweighers. If a product's weight is outside an acceptable range, the product is separated from the acceptable products. The separation is typically achieved by positioning a rejector downstream of a weighing station to divert rejected, out-of-range products to a reject conveyor for corrective action. The transfer of products from one device-the weighing system-to a second device-the rejector-can cause positioning errors that result in false rejects. And using two separate devices adds complexity and risk.

<CIT> discloses a weighing system according to the preamble of claim <NUM> and a conveyor belt according to the preamble of claim <NUM>. has electrically conductive rollers that are rotated with a constant torque in a lateral direction by a linear induction stator defining a roller-activation zone along a carryway. Because the lateral acceleration of a conveyed object is inversely proportional to the object's weight, lighter objects are displaced farther and at greater speeds than heavier objects. So their weights can be determined from the lateral acceleration, speed, or displacement. And objects can be sorted off the side of the belt by weight.

<CIT> discloses a conveyor and associated method for diverting closely spaced articles conveyed along the conveyor. The conveyor includes a conveyor belt with belt rollers oriented to rotate on axes oblique to the direction of belt travel. A series of arrays of bearing surface elements are arranged end to end along the length of the conveyor. The bearing surfaces may be static or rotational. Each array defines a roller-control zone in which the array is selectively activated with its bearing surface elements in contract with the belt rollers or deactivated with its bearing surface elements out of contact with the belt rollers. As the belt advances through an activated roller-control zone, the belt rollers rotate to propel a conveyed article toward a side of the belt. The contiguous roller-control zones are sequentially activated and deactivated to direct articles to the side and off the belt or to let them pass straight through. The length of the entire series of roller-control zones determines the lateral extent of the sidewise diversion. The length of each roller-control zone determines the minimum gap between consecutively conveyed articles. The serial cascade of these roller-control zones permits the tight sortation of closely spaced articles for high throughput.

In one aspect, the present invention provides a weighing system in accordance with claim <NUM>.

In another aspect, the present invention provides a conveyor belt in accordance with claim <NUM>.

One version of a weighing system embodying features of the invention is shown in <FIG>. The weighing system <NUM> includes a conveyor belt <NUM> advancing along a travel path from an upstream end <NUM> to a downstream end <NUM> in a travel direction <NUM>. The conveyor belt <NUM> is a roller belt having a plurality of article-supporting belt rollers <NUM> extending above the belt's outer face. The belt rollers <NUM> shown in <FIG> are arranged to rotate on axes <NUM> oblique to the travel direction <NUM>. One example of roller belt with obliquely rotatable rollers is disclosed in <CIT>. Commercial versions include the INTRALOX® Series <NUM> Angled Roller Belt manufactured and sold by Intralox, L. of Harahan, Louisiana, U. Another example of a roller belt is disclosed in <CIT>. The rollers described in that patent rotate on axes parallel to the travel direction. Commercial versions include the INTRALOX® Series <NUM> Belt. Yet another roller belt is the ball belt disclosed in <CIT>. The spherical rollers described in that patent rotate about all axes. Commercial versions include the INTRALOX® Series <NUM> Ball Belt. Or the rollers can be stacked oblique rollers in which a bottom roller is actuated to rotate a top article-supporting roller in the opposite direction. A roller belt with stacked rollers is disclosed in <CIT>. Commercial versions include the INTRALOX® Series <NUM> DARB Belt.

An infeed conveyor <NUM> feeds articles <NUM> onto the roller belt <NUM> at the upstream end <NUM> of the weighing system <NUM>. The articles <NUM> sit atop the rollers <NUM> and are conveyed along a first length of the travel path through a weighing zone <NUM>. Because the belt rollers <NUM> are not actuated in the weighing zone <NUM>, the articles <NUM> pass through the weighing zone without being diverted from the travel direction <NUM> by the rollers. The articles <NUM> are weighed as they pass through the weighing zone <NUM>. The conveyor belt <NUM> then conveys the articles into a second length of the travel path defined by a roller-actuation, or sorting, zone <NUM> downstream of the weighing zone <NUM>. In this version the roller-actuation zone <NUM> comprises two sequential roller-actuation subzones 28A, 28B. Actuators <NUM> in the roller-action zone <NUM> are selectively actuated and deactuated as a function of the weights of the articles atop the rollers. For example, when actuated, the actuator <NUM> causes the belt rollers <NUM> to rotate on their axes <NUM> oblique to the travel direction and to push articles, such as out-of-range articles 24A, 24B whose weights are outside a predetermined acceptable weight range, off the side of the belt and onto reject conveyors 32A, 32B. Weights outside the acceptable weight range can be can be divided into two or more unacceptable subranges. For example, the two roller-actuation zones as in the version shown in <FIG> could each correspond to one of two unacceptable weight ranges. All the out-of-range articles 24A whose weights are less than a predetermined unacceptable weight could be diverted in the first roller-actuation subzone 28A, and all those articles 28B whose weights exceed the predetermined unacceptable weight could be diverted off in the second subzone 28B. The rollers <NUM> supporting acceptable in-range articles <NUM>" are deactuated as they pass through the roller-actuation zone <NUM>. The acceptable articles are delivered over the conveyor's downstream end <NUM> to a discharge conveyor 34A, 34B. In that way rejected out-of-range articles 24A, 24B exit the conveyor belt <NUM> along a different path from the in-range articles 24C. And because a single conveyor belt <NUM> conveys the articles <NUM> through both the weighing zone <NUM> and the roller-actuation zone <NUM> without intervening belt-to-belt transfers, false rejects due to positioning errors are reduced. More than two roller-actuation subzones could be used to sort out-of-range articles to multiple reject conveyors according to out-of-range weight subranges into which they fall. Or the sorting can be organized according to other criteria, such as destination and package type, as just two examples.

<FIG> show a belt roller <NUM> with a weight sensor to measure the weights of articles. The cylindrical roller <NUM> is mounted on an axle <NUM> that defines the roller's axis of rotation <NUM>. The weight sensor comprises three load cells <NUM>, which are connected between the roller's periphery <NUM> and a hub <NUM> surrounding the axle <NUM>. The three load cells <NUM> in this example are equi-spaced around the axle <NUM>. The load cells <NUM> are electrically connected to associated support circuitry <NUM>. The three load cells <NUM> resolve the downward force F, which is proportional to the weight of an article sitting atop the roller. The sums of the downward forces on all the rollers supporting an article equal the article's total weight.

Instead of being incorporated into the rollers as in <FIG>, the weight sensor shown in <FIG> is embedded in the conveyor belt. The conveyor belt <NUM> shown in <FIG> is a modular conveyor belt constructed of a series of rows <NUM> of one or more belt modules, such as the module <NUM> shown in <FIG>. The rows <NUM> are hingedly linked together by hinge rods <NUM> at hinge joints. In this version the roller <NUM> is mounted on an axle <NUM> that is oriented parallel to the travel direction <NUM>. The ends of the axle <NUM> are supported from below on load cells <NUM>, <NUM> embedded in the module <NUM>. A downward force F on the article-supporting roller <NUM> is measured by the two load cells <NUM>, <NUM>. The sum of the outputs of the two load cells <NUM>, <NUM> equals the applied force F. Like the load cells in <FIG>, the load cells <NUM>, <NUM> in <FIG> are associated with support circuitry to be described later.

The weighing system <NUM> shown in <FIG> is operated as a conveyor switch. A roller conveyor belt <NUM> is divided across its width into two parallel longitudinal lanes <NUM>, <NUM> that extend from the upstream end <NUM> to the downstream end <NUM>. The infeed conveyor <NUM> feeds articles <NUM> onto the first lane <NUM> at the upstream end <NUM> of the conveyor belt <NUM>. The articles <NUM> are weighed in the first lane <NUM> in the weighing zone <NUM>. The roller-actuation zone <NUM> is selectively actuated either only for articles <NUM> whose weights are in-range or only for articles whose weights are out-of-range. When selectively actuated, the belt rollers <NUM> divert the articles from the first lane <NUM> to the second lane <NUM>. Thus, the selectively diverted articles <NUM>' are switched to the second lane <NUM> to exit the downstream end <NUM> of the conveyor belt <NUM> onto a discharge conveyor <NUM>. The roller-actuation zone <NUM> is deactuated for articles <NUM>" that are not selected to be switched to the second lane <NUM>. Instead, those articles <NUM>" remain in the first lane <NUM> to exit onto a separate discharge conveyor <NUM>. In another version the conveyor belt comprises two side-by-side abutting conveyor belts, in which the second conveyor belt can be, but does not have to be, a roller belt.

Various ways of collecting and using the weight measurements for weighing conveyors in which the weight sensor is integrated into the conveyor belt or its rollers are shown in <FIG> represents a passive system in which the belt has only passive components. A load cell <NUM>, such as a load cell <NUM> as in <FIG> or a load cell <NUM>, <NUM> as in <FIG>, in the belt <NUM> is electrically connected to a transmitter <NUM> realized as a capacitor plate or a coil. A receiver <NUM> external to and below the belt <NUM> in the weighing zone is realized as a second capacitor plate forming a capacitor with the plate in the belt or as a second coil forming a transformer with the coil in the belt. Thus, the weight sensor's weight signal <NUM> is sent by the transmitter <NUM> to the external receiver <NUM> by capacitive or inductive coupling when the sensor <NUM> is in the weighing zone. The received weight signal is conditioned, including being converted from an analog weight signal <NUM>' into a digital weight signal <NUM> in a conditioning circuit <NUM> before being sent to a controller <NUM>, which may be realized as a programmable logic controller or other programmable computing device executing program steps stored in a program memory. The controller <NUM> also receives weight signals from other weight sensors and, from those signals, determines the weight of an article, compares its weight to a predetermined weight range, classifies the article as out-of-range if its weight is outside the weight range or as in-range if within, and selectively sends an actuation signal <NUM> to the actuator <NUM> in the actuation zone for either only the out-of-range articles or only the in-range articles to rotate the belt rollers to divert the in-range and out-of range articles off the belt along different exit paths.

Another version of support circuitry to transmit weight signals from the belt to the external controller <NUM> is shown in <FIG>. The circuitry on board the belt <NUM> includes the load cell <NUM>, a local controller <NUM>, and a transmitter <NUM>. The analog weight signal <NUM> is converted to a digital weight signal <NUM> by the controller <NUM> and an associated analog-to-digital converter. The digital weight signal <NUM> is then transmitted by the transmitter to an external receiver <NUM> while the weight sensor is in the weighing zone. The received digital weight signal <NUM>' passes through an interface circuit <NUM> on its way to the controller <NUM>, which determines the weight of the article and either actuates or deactuates the belt rollers as they convey the article through the roller-actuation zone. The belt-borne components receive power from an external power supply <NUM>, which is coupled to a power receiver <NUM> including a voltage regulator, in the belt. Power transfer to the power receiver <NUM> can be by inductive or capacitive coupling, by light transmission, or by sliding electrical contacts, as just a few examples.

Yet another version of support circuitry is shown in <FIG>, which is similar to <FIG>, except that <FIG> shows a storage element <NUM>, such as one or more dry cells or capacitors, powering the weight-sensor circuit. The external power source <NUM> is optionally coupled to a local charging circuit <NUM> in the belt to recharge the rechargeable storage element <NUM> wirelessly or via contacts.

Claim 1:
A weighing system (<NUM>) comprising:
a conveyor belt (<NUM>; <NUM>) arranged to advance in a travel direction (<NUM>) along a travel path from an upstream end (<NUM>) to a downstream end (<NUM>) and having a plurality of article-supporting rollers (<NUM>; <NUM>; <NUM>) actuatable to rotate toward a side of the conveyor belt (<NUM>; <NUM>) in a transverse direction transverse to the travel direction (<NUM>);
a weighing zone (<NUM>) extending along a first length of the travel path in which one or more weight sensors measure the weights of articles (<NUM>) conveyed by the conveyor belt (<NUM>; <NUM>) and produce weight signals (<NUM>) indicative of the weights of the articles;
a roller-actuation zone (<NUM>) extending along a second length of the travel path;
wherein, in the roller-actuation zone (<NUM>), an actuator (<NUM>) selectively actuates the article-supporting rollers (<NUM>; <NUM>; <NUM>) as they pass through to push articles (<NUM>) in the transverse direction;
characterised in that the weighing system (<NUM>) comprises a controller (<NUM>):
receiving the weight signals (<NUM>);
determining the weights of the articles (<NUM>) from the weight signals (<NUM>);
selectively actuating and deactuating the rollers (<NUM>; <NUM>; <NUM>) passing through the roller-actuation zone (<NUM>) as a function of the weights of the articles (<NUM>);
wherein the weight sensors are coupled to the rollers (<NUM>; <NUM>; <NUM>) to measure the downward forces (F) on the rollers (<NUM>; <NUM>; <NUM>) applied by the conveyed articles (<NUM>) atop the rollers (<NUM>; <NUM>), the weight signals (<NUM>) being proportional to the downward forces (F).