The field of the present disclosure relates to electronic weighing instruments in general, and specifically to methods and devices for establishing zero-points for an electronic scale.
Electronic scales are important commercial tools used to determine the weight of various objects in numerous settings. A common example is an electronic scale, such as those used at grocery stores, used singly or operatively connected to other electronics such as a data reader, point of sale system, or other suitable electronic equipment. Electronic scales are commonly calibrated by the manufacturer or a certified individual to establish an absolute zero-point. The term “zero-point” is used to designate a weight detected by an electronic weighing instrument where the detected weight is associated with a display of “0” units of weight measurement, such as pounds, kilograms, etc. An absolute zero-point typically provides a zero indication, such as the numeral “0” shown on an electronic display, when the electronic weighing instrument detects no object on the scale. In other words, the absolute zero-point, or calibrated zero-point, corresponds to the weight detected by an electronic scale when it detects the weight of its own components, such as a weigh platter.
Maintenance and repair costs associated with electronic scales having only an absolute zero-point are relatively high because the absolute zero-point should be maintained to facilitate use of the electronic scale, or the scale should be recalibrated from time-to-time to re-establish the absolute zero-point. If a scale component is replaced, becomes worn, or is damaged, the electronic scale will detect a weight different from the weight used to establish the absolute zero-point and will provide an indication other than zero when there is no object to be weighed unless the absolute zero-point is recalibrated. Thus, use and maintenance of the electronic scale may be cumbersome and relatively expensive.
Two common devices developed to address the situation when an electronic scale does not detect the absolute zero-point are an initial zero device and a semi automatic zero device. An initial zero device operates when an electronic scale is powered on, and uses the weight detected when powered on to establish an initial zero-point. Thus, whatever weight is detected at power on, such as the weight of the electronic scale components alone or the weight of such components plus the weight of an object, is associated with the initial zero-point. A semi-automatic zero device operates after power on and uses the weight detected when the semi-automatic zero device is activated to establish a current zero-point. Semi-automatic zero devices are commonly activated by an operator pressing a “0” or “zero” button on an electronic scale.
Organisation Internationale De Métrologie Légale (OIML) International Recommendation R 76-1:2006(E) establishes technical requirements for non-automatic weighing instruments. Section 4.5 of OIML R 76-1:2006(E) governs semi-automatic zero devices. Specifically, subsection 4.5.1 provides that the overall effect of semi-automatic zero devices shall not be more than 4% of the maximum weighing capacity of the instrument. In other words, the semi-automatic zero device may establish a current zero-point if the electronic scale detects a weight change that falls within a range having an upper limit and a lower limit where the difference between the upper limit and the lower limit is not more than 4% of the maximum weighing capacity of the scale.
Subsection 4.5.1 of OIML R 76-1:2006(E) also provides that the overall effect of an initial zero device shall not be more than 20% of the maximum weighing capacity of the instrument. In other words, the initial zero device may establish an initial zero-point if the electronic scale detects a weight that falls within a weight range having an upper limit and a lower limit where the difference between the upper limit and the lower limit is not more than 20% of the maximum weighing capacity of the scale.
The present inventors have recognized various problems associated with electronic scales that comply with the above technical requirements of OIML R 76-1:2006(E). One such problem relates to electronic scales establishing an initial zero-point when a relatively heavy object is on the scale at power on. Removal of the object after power is supplied to the electronic scale causes the scale to be unable to establish a current zero-point. Another such problem relates to electronic scales limited to establishing an initial zero-point only with a relatively light weight on the scale. Subsequent wear or damage to such a scale commonly results in a relatively heavy phantom weight detected by the scale and prevents the scale from establishing an initial zero-point.
Embodiments of the present invention may address some or all of the above identified limitations and/or needs, or may address other suitable needs. An exemplary apparatus/system or method for establishing initial zero-points and current zero-points includes an initial zero device programmed to establish an initial zero-point and a semi-automatic zero device programmed to establish a current zero-point or to reset or power cycle a scale when a current zero-point cannot be established.
Additional aspects and advantages will be apparent from the following detailed description of preferred embodiments, which proceeds with reference to the accompanying drawings.
The present inventors have recognized various problems associated with electronic scales having initial zero devices and semi-automatic zero devices that conform to the technical requirements of OIML R 76-1:2006(E). One such problem relates to powering on an electronic scale bearing an initial weight other than the weight of the instrument's own components.
When currently existing electronic scales are powered on, such electronic scales detect an initial weight. If the initial weight is outside the IZR, a fault is detected and the electronic scale is made inoperative until some or all of the initial weight is removed. Once enough of the initial weight has been removed to fall within the IZR, the initial zero device establishes an initial zero-point based on the initial weight and the instrument's display outputs a zero reading while the initial weight is on the scale. Alternately, if the initial weight falls within the IZR the initial zero device establishes an initial zero-point and the display outputs a zero reading. As illustrated in
The electronic scale may be used to weigh objects with the initial weight in place, but commonly the initial weight is removed. With reference to
When the flashing “-0-” symbol appears, scale operators typically activate a semi-automatic zero device by pushing a “0” or “zero” button to establish a current zero-point. However, under the requirements of OIML R 76-1:2006(E) a semi-automatic zero device can only establish a current zero-point if the detected weight on the scale is within 4% of the maximum weighing capacity of the scale compared to the last weight used to establish a zero-point. For the hypothetical example illustrated in
However, when the 13% of maximum weighing capacity initial weight used to establish the initial zero-point is removed, the scale detects 0% of the maximum weighing capacity and the semi-automatic zero device cannot establish a current zero-point because of the technical requirements of OIML R 76-1:2006(E). Therefore, pressing a “0” or “zero” button does not cause the semi-automatic zero device in typical, current electronic scales to establish a zero-point under such circumstances.
When typical, current semi-automatic zero devices cannot establish a current zero-point, for example, because an under or over weight condition outside the 4% maximum weighing capacity range exists, the same flashing “-0-” symbol, or other suitable symbol, is typically provided as an indication that a current zero-point cannot be established. In response, operators commonly attempt to establish a current zero-point by activating the semi-automatic zero device, but do not understand what to do when a current zero-point cannot be established. Typically operators make a service request for the electronic scale when a current zero-point cannot be established. Such service requests are expensive due to the electronic scale's downtime and the cost associated with a technician visiting and servicing the electronic scale.
A preferred system and method for establishing zero-points for an electronic scale address the inability of current electronic scales with an initial zero device and a semi-automatic zero device to establish a current zero-point after a relatively heavy item used to establish an initial zero-point is removed from a scale.
The initial zero device 20 and semi-automatic zero device 25 are preferably embodied as programmable logic and may each include one or more of hardware, firmware, software, or other suitable programmable logic. In an alternate embodiment, initial zero device 20 and semi-automatic zero device 25 may be included as part of processor 15.
The initial zero device 20 and semi-automatic zero device 25 are preferably programmed to carry out certain of the method steps illustrated in
The initial zero device 20 is programmed to execute an initial zero process.
For step 310, if the initial weight is outside the IZR the initial zero device 20 is preferably programmed to determine that an initial zero-point cannot be established. When an initial zero-point cannot be established, the initial zero device 20 is also programmed to return to step 305 to restart the initial zero process.
For step 310, if the initial weight is within the IZR, the initial zero device 20 is preferably programmed to proceed to step 315 where the initial zero device 20 is programmed to set the initial weight as a reference weight. At step 320 the initial zero device 20 is programmed to establish the reference weight as the initial zero-point.
For step 325 the processor 15 is programmed to use the initial zero-point in conjunction with signals received from the weight detecting device 10 to carry out weighing operations for items placed on scale 5.
The semi-automatic zero device 25 is programmed to execute a current zero process. For step 330, the semi-automatic zero device 25 is programmed to determine whether the semi-automatic zero device 25 has been activated. For example, the semi-automatic zero device 25 may be programmed to receive a signal generated by an operator pressing a “0” or “zero” button on scale 5. If the semi-automatic zero device 25 does not detect an activation signal, then the processor 15 continues to perform weighing operations at step 325.
If the semi-automatic zero device 25 detects an activation signal at step 330, it is programmed to receive a signal indicative of the amount of the current weight for step 335, for example, from the processor 15 or directly from the weight detecting device 10. For step 340, the semi-automatic zero device 25 is programmed to determine whether the current weight falls within the SAZR. According to OIML R 76-1:2006(E), the difference between the upper and lower limits of the SAZR can be no more than 4% of the maximum weighing capacity of scale 5. Additionally, the difference between the upper or lower limit of the SAZR and the initial zero-point can be no more than 4% of the maximum weighing capacity of scale 5. For example,
Note that the weights corresponding to the upper and lower limits of the SAZR will change each time a zero-point is established because the SAZR is based on the currently existing zero-point. In contrast, the weights corresponding to the upper and lower limits of the IZR preferably do not change as it is preferable to have the same IZR used each time scale 5 is powered on or is reset.
For step 340, if the current weight is within the SAZR, the semi-automatic zero device 25 is preferably programmed to proceed to step 315 where the semi-automatic zero device 25 is programmed to set the current weight as the reference weight. At step 320 the semi-automatic zero device 25 is programmed to establish the reference weight as the current zero-point. Alternately, the semi-automatic zero device 25 may be programmed to pass the current weight to the initial zero device 20 and the initial zero device 20 may be programmed to set the current weight as the reference weight at step 315 and to establish the reference weight as the current zero-point at step 320.
For step 325 the processor 15 is programmed to use the current zero-point in conjunction with signals received from the weight detecting device 10 to carry out weighing operations for items placed on scale 5.
For step 340, the semi-automatic zero device 25 is preferably programmed to determine whether the current weight is outside the SAZR. If the semi-automatic zero device 25 determines the current weight is outside the SAZR, the semi-automatic zero device 25 is preferably further programmed to proceed to step 345 and determine that a fault has occurred. At step 345 the semi-automatic zero device 25 is also preferably programmed to automatically make scale 5 inoperable, or to provide a visual or audible indication of the fault.
The semi-automatic zero device 25 is preferably further programmed to initiate a reset or power cycle procedure for scale 5 at step 350. A reset or power cycle procedure may include clearing the existing zero-point and the reference weight and restarting processing with the initial zero device 20 at step 305. Alternately, a reset or power cycle procedure may include shutting down scale 5 and restarting scale 5 without operator intervention followed by processing starting with the initial zero device 20 at step 305.
Operation of a preferred initial zero device 20 and semi-automatic zero device 25 thus provides improved operation for scale 5 compared to currently existing initial zero and semi-automatic devices. As discussed above, current electronic scales complying with OIML R 76-1:2006(E) typically cannot establish a current zero-point after a relatively heavy item present when establishing an initial zero-point is thereafter removed from the scale. Such failure to establish a current zero-point commonly results in a service request for the scale, often because the operator does not understand the meaning of the flashing “-0-” symbol. In contrast, after a relatively heavy item was present when establishing an initial zero-point is thereafter removed from the scale 5, using an initial zero device 20 and a semi-automatic zero device 25 programmed to execute the method discussed above and illustrated in
The present inventors have recognized another problem related to electronic weighing instrument manufacturers limiting a currently existing initial zero device to establishing an initial zero-point only when an initial weight (in addition to the weight of the electronic weighing instrument's own components used to establish the absolute zero-point) does not exceed 4% of the electronic scale's maximum weighing capacity. Placing such a 4% limitation on currently existing initial zero devices permits a currently existing automatic zero device to consistently establish a current zero-point when an initial weight is removed. However, if a scale component is replaced (for example, with a component having a weight that is greater than 4% of the electronic scale's maximum weighing capacity), becomes worn, or is damaged, the scale may detect a real weight (for example, due to a replaced component) or a phantom weight (for example, due to a false reading caused by a worn or damaged component) that exceeds the 4% limitation imposed on the initial zero device. In such a situation neither a currently existing initial zero device nor a currently existing semi-automatic zero device can establish a zero-point and the scale needs to be recalibrated or repaired.
However, using an initial zero device 20 and a semi-automatic zero device 25 programmed to execute the method discussed above and illustrated in
Consider a currently existing scale having a maximum weighing capacity of 100 pounds and an initial zero device that is limited to establishing an initial zero-point only when the initial weight detected by the scale is 4 pounds or less. Components of the scale may become damaged if a relatively heavy item, such as a frozen turkey, is dropped onto the scale. For example, the scale may include a processor communicating with a load cell having multiple strain gages attached to a beam. When the beam deflects, the electrical resistance of the strain gages proportionally changes and the processor can determine the weight of the item causing the beam to deflect. If the frozen turkey dropped on the scale causes a permanent deformation of the beam to a position where the processor determines there is 7 pounds on the scale, when the scale is next cycled off and then back on the processor will detect a phantom weight of 7 pounds. That is, the processor will detect a 7 pound weight that is not actually present due to the permanently deflected beam. Therefore, when the scale is powered on, the initial zero device will not be able to establish an initial zero-point because the 7 pound phantom weight exceeds the 4 pound limitation placed on the initial zero device. Likewise, the semi-automatic zero device will not be able to establish a current zero-point because there is no existing zero-point from which to determine the SAZR. The scale will thus need to be recalibrated or repaired before it can be used again.
In one example implementation, a scale 5 is provided having a maximum weighing capacity of 100 pounds, an initial zero device 20, and a semi-automatic zero device 25 (where both the initial zero device 20 and the semi-automatic zero device 25 are programmed to execute the method discussed above and illustrated in
The terms and descriptions used above are set forth by way of illustration only and are not meant as limitations. Those skilled in the art will recognize that many variations can be made to the details of the above-described embodiments without departing from the underlying principles of the invention. The scope of the present invention should, therefore, not be limited to the above specific examples, but is defined by the claims below.
This application claims priority under 35 U.S.C. §119(e) to U.S. Application No. 61/294,056 filed on Jan. 11, 2010 and to U.S. Application No. 61/294,379 filed on Jan. 12, 2010, both of which are fully incorporated herein by reference.
Number | Date | Country | |
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61294056 | Jan 2010 | US | |
61294379 | Jan 2010 | US |