Weight measuring system with automatic gain correction
First Claim
1. In an electronic weigh system comprising auto gain means for automatically correcting the gain of the weigh system so as to maintain an accurate relationship between the weight of a load being measured and the value displayed or recorded, the weighing system being such that a train of pulses representing, by its repetition rate, the weight of the load, is counted over a predetermined time interval, the improvement comprising:
- means for establishing said predetermined time interval by counting a predetermined number of pulses in a network supplied with clock pulses and with additional pulses, the number of which additional pulses corresponds to a nominal value if the required gain correction is zero but which otherwise corresponds to a correction value which varies about the nominal value according to the magnitude and sign of the correction of gain required, means for introducing a reference into a load measuring circuit to simulate precisely a predetermined load value, means for passing the reference weight pulses to a gain counter over a nominal time interval and means for utilising the least significant digits of the count to the same order as the nominal value to represent the correction value for determining the number of additional pulses to be fed to said network during each weighment.
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Abstract
In electronic measuring systems the accuracy of measurement is affected by drift not only of the zero but of the gain due to temperature changes, aging and supply conditions. The invention provides an automatic gain correction means so as to maintain an accurate relationship between the magnitude of the characteristic being measured and the value displayed or recorded. The measuring system is such that a train of pulses is counted over a predetermined time interval with a train of pulses representing, by its pulse repetition rate, the magnitude of the characteristic. A reference count is provided and means are provided for generating a pulse train simulating a predetermined magnitude of the characteristic being measured. Means are provided for counting the pulses of the generated pulse train and means are provided for comparing the reference count with the count of the generated pulse train to determine any error in the gain. Means are provided for automatically adjusting the predetermined time interval to correct the effect of the determined gain error.
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Citations
20 Claims
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1. In an electronic weigh system comprising auto gain means for automatically correcting the gain of the weigh system so as to maintain an accurate relationship between the weight of a load being measured and the value displayed or recorded, the weighing system being such that a train of pulses representing, by its repetition rate, the weight of the load, is counted over a predetermined time interval, the improvement comprising:
- means for establishing said predetermined time interval by counting a predetermined number of pulses in a network supplied with clock pulses and with additional pulses, the number of which additional pulses corresponds to a nominal value if the required gain correction is zero but which otherwise corresponds to a correction value which varies about the nominal value according to the magnitude and sign of the correction of gain required, means for introducing a reference into a load measuring circuit to simulate precisely a predetermined load value, means for passing the reference weight pulses to a gain counter over a nominal time interval and means for utilising the least significant digits of the count to the same order as the nominal value to represent the correction value for determining the number of additional pulses to be fed to said network during each weighment.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. Apparatus for automatically correcting the gain of an electronic measuring system so as to maintain an accurate relationship between the magnitude of the characteristic being measured and the value displayed or recorded, the measuring system being such that a train of pulses is counted over a predetermined time interval with the train of pulses representing, by its pulse repetition rate, the magnitude of said characteristic, the improvement comprising, in combination:
- means for providing a reference count, means for generating a pulse train simulating a predetermined magnitude of said characteristic;
means for counting the pulses of the generated pulse train;
means for comparing the reference count with the count of the generated pulse train to determine any error in the gain; and
means for automatically adjusting the predetermined time interval to correct the effect of the determined gain error. - View Dependent Claims (13, 14, 15)
- means for providing a reference count, means for generating a pulse train simulating a predetermined magnitude of said characteristic;
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16. A method for automatically correcting the gain of an electronic measuring system so as to maintain an accurate relationship between the magnitude of the characteristic being measured and the value displayed or recorded, the measuring system being such that a train of pulses is counted over a predetermined time interval with the train of pulses representing, by its pulse repetition rate, the magnitude of such characteristic, the improvement comprising the steps of:
- providing a reference count;
generating a pulse train simulating a predetermined magnitude of said characteristic;
counting the pulses of the generator pulse train;
comparing the reference count with the count of the generated pulse train to determine any error in the gain; and
automatically adjusting the predetermined time interval to correct the effect of the determined gain error. - View Dependent Claims (17, 18, 19, 20)
- providing a reference count;
Specification