Apparatus and method for counting a plurality of similar articles

• US 4,982,412 A
• Filed: 03/13/1989
• Issued: 01/01/1991
• Est. Priority Date: 03/13/1989
• Status: Expired due to Term

• Current Assignee: Moore Push Pin Company
• Original Assignee: Moore Push Pin Company
• Inventors: Gross, Barry M.
• Primary Examiner(s): Heyman, John S.
• Application Number:
  US07/322,715
• Time in Patent Office: 659 Days
• Field of Search: 377/6, 377/8, 377/10, 377/11, 377/28, 377/29, 221/2, 53/500, 250/222.1
• US Class Current: 377/6
• CPC Class Codes: G06M 7/04 Counting of piece goods, e.g. of boxes

Abstract

A counting device determines the number of similar articles, or parts, passing a detector. The device is especially useful in packaging small parts into containers, and in insuring that each package contains the correct number of parts. The counter is preferably of the type in which the parts interrupt a beam of light, changing the current through a photoelectric cell. When the current in the photoelectric cell falls below a predetermined threshold level, the device generates a pulse which indicates the presence of a part. The pulses are counted electronically. The device preferably includes a microprocessor which can efficiently control the counting, calibration, and diagnostic operations. The microprocessor stores information relating to the threshold current level, for a given type of part. The value of the threshold can be determined by a separate calibration procedure. The microprocessor is programmed to ignore pulses received for a predetermined time interval following the leading edge of a pulse, so as not to count the same part twice. The invention also includes circuitry for detecting faults in the system, such as an open-circuited or short-circuited photoelectric cell. The device also contains circuits for determining whether the wrong types of parts have been mixed into the batch being counted, and for determining whether more than one part has passed the photoelectric cell. The latter tests are based on a comparison of the observed level of current flowing through the detector with an expected level.

Claims

1. In an apparatus for counting a plurality of parts, the apparatus including photoelectric means for sensing the presence of a part by observing the blockage of a beam of radiation caused by the presence of a part, and means for counting electrical pulses generated by the sensing means in response to the presence of a part, the improvement comprising a programmed computer for deactivating the counting means for an adjustable interval following the leading edge of one of said pulses, the computer being programmed to deactivate the counting means immediately upon detection of said leading edge, the interval being adjusted in accordance with the length of the parts being counted, wherein the apparatus counts a given part only one time.

2. Apparatus for counting a plurality of parts, comprising:

(a) means for directing said parts between a source of radiation and a detector of said radiation, so as to detect the presence of a part by sensing the amount of radiation received by the detector, and

(b) programmable means for storing a value related to the level of current in the detector which must be observed in order to record a count, said level of current being called the programmed threshold current,

(c) programmable means comprising means for comparing the stored value with the actual current flowing through the detector, and for recording a count when the actual current falls below the programmed threshold current for a predetermined period of time,

the programmable means also comprising means for measuring the lengths of a plurality of parts passing the detector, and means for setting said period equal to or less than the shortest observed part.

3. A method of counting parts, comprising the steps of:

(a) determining whether a part is present by passing the part between a source of radiation and a detector, observing a change in current through the detector due to the blockage of radiation, and recording a count when the current in the detector falls below a programmed threshold,

(b) setting a timer immediately upon determining that the current in the detector has fallen below the programmed threshold, the timer being programmed to wait for a predetermined time interval, the interval being based on the length of the parts being counted, and

(c) resuming the counting only after the delay timer has reached the end of the predetermined interval.

4. A method of counting parts, comprising the step of determining whether a part is present by passing the part between a source of radiation and a detector, observing a change in current through the detector due to the blockage of radiation, and recording a count when the current level in the detector falls below a programmed threshold level, the method also comprising the step of performing at least one diagnostic test on the detector while the counting is being performed, the diagnostic test being performed substantially independently of the count-recording step, such that the result of the test is determined without regard to the number of counts being recorded.

5. The method of claim 4, wherein the diagnostic test includes testing for an open-circuited condition in the detector.

6. The method of claim 5, wherein the testing step comprises the step of determining whether the voltage at the detector has increased beyond a predetermined level.

7. The method of claim 6, wherein the detector is connected to an operational amplifier, and wherein the determining step includes the step of determining whether the output of the operational amplifier has fallen below a predetermined value.

8. The method of claim 4, wherein the diagnostic test includes testing for a short-circuited condition in the detector.

9. The method of claim 8, wherein the detector is connected to an operational amplifier, and wherein the testing step includes the step of determining whether the output of the operational amplifier has become too high.

10. The method of claim 4, wherein the diagnostic test includes determining whether the level of current in the detector is inconsistent with the type of part being counted.

11. The method of claim 10, wherein the determining step includes the steps of establishing a second threshold level, the second threshold level being different from the programmed threshold, and determining whether the current in the detector lies between the programmed threshold and the second threshold.

12. A method of calibrating a counting device, the counting device being of the type wherein a part to be counted is passed between a source of radiation and a detector, and wherein the device performs the counting by observing the blockage of radiation to the detector, the method comprising the steps of causing a plurality of parts to be counted to pass the detector, measuring the length of each such part by measuring the time during which radiation is blocked by the passage of each part, storing the length of the longest measured part, computing a value based on the stored maximum part length, using said value in subsequent runs of the device, such that the counting device is disabled, beginning with the detection of a part, for a time corresponding to said stored value.

13. The method of claim 12, wherein the counter does not record a count unless the radiation is blocked for a predetermined minimum amount of time, and wherein said minimum is determined by storing the minimum length of parts passing the detector, computing a value less than or equal to the stored minimum part length, and using the latter value in subsequent runs of the device, such that the counting device does not record a count unless the radiation is blocked for a time longer than the latter value.

14. A method of calibrating a counting device, the device including a source of radiation and a detector of said radiation, wherein parts to be counted are caused to pass between the source of radiation and the detector, so as to block radiation entering the detector, the method comprising the steps of measuring the current in the detector when there is no part blocking the radiation, storing the value of measured current, repeating the measuring and storing steps after a predetermined interval, comparing the measured amounts of current, and halting the system if the latter two values are not sufficiently close to each other.

15. A method of calibrating a counting device, the device including a source of radiation and a detector of said radiation, wherein parts to be counted are caused to pass between the source of radiation and the detector, so as to block radiation entering the detector, the counting device being capable of recording a count when the detector current falls below a programmed threshold, the counting device including an operational amplifier and a microprocessor, the microprocessor supplying a voltage to the amplifier, said voltage being related to a programmed threshold current, the method comprising the steps of determining a first value by measuring the signal needed from the microprocessor to record a count when there is no part blocking the detector, determining a second value by measuring the change in output of the amplifier due to the presence of the part and scaling said second value if necessary, and setting said voltage equal to the difference between the first and second values, said voltage being stored in the microprocessor and being used in subsequent operation of the counting device.

16. Apparatus for counting a plurality of parts, comprising:

(a) means for directing said parts between a source of radiation and a detector of said radiation, so as to detect the presence of a part by sensing the amount of radiation received by the detector,

(b) programmable means for storing a value related to the level of current in the detector which must be observed in order to record a count, said level of current being called the programmed threshold current, and

(c) means for comparing the stored value with the actual current flowing through the detector, and for recording a count when the actual current falls below the programmed threshold current,

wherein the programmable means includes a microprocessor, the microprocessor being connected to a digital-to-analog converter, the converter being connected to the comparing means.

17. The apparatus of claim 16, wherein the apparatus includes first means for determining the amount of current flowing through the detector when there is no part present, second means for determining the amount of current flowing through the detector when a part blocks the radiation entering the detector, and means for storing the above-mentioned amounts.

18. The apparatus of claim 17, wherein the second means includes means for discharging a capacitor to a voltage which is related to the amount of current flowing through the detector when a part is present, means for comparing the voltage across the capacitor with a reference voltage, and means for varying the reference voltage until the reference voltage equals the voltage across the capacitor.

19. The apparatus of claim 18, further comprising means for recharging the capacitor to a voltage related to the maximum amount of current flowing through the detector when a part is not present.

20. Apparatus for counting a plurality of parts, comprising:

(a) means for directing said parts between a source of radiation and a detector of said radiation, so as to detect the presence of a part by sensing the amount of radiation received by the detector,

(b) programmable means for storing a value related to the level of current in the detector which must be observed in order to record a count, said level of current being called the programmed threshold current, and

(c) means for comparing the stored value with the actual current flowing through the detector, and for recording a count when the actual current falls below the programmed threshold current,

the apparatus further comprising means for testing whether the detector has become open-circuited, the testing means being substantially simultaneously operable while the apparatus is counting parts,

wherein the open-circuit testing means comprises means for determining whether the voltage at the detector has increased beyond a predetermined level.

21. The apparatus of claim 20, wherein the detector is connected to an operational amplifier, and wherein the open-circuit testing means also comprises means for determining whether the output of the operational amplifier has fallen below a predetermined value.

22. Apparatus for counting a plurality of parts, comprising:

(a) means for directing said parts between a source of radiation and a detector of said radiation, so as to detect the presence of a part by sensing the amount of radiation received by the detector,

(b) programmable means for storing a value related to the level of current in the detector which must be observed in order to record a count, said level of current being called the programmed threshold current, and

(c) means for comparing the stored value with the actual current flowing through the detector, and for recording a count when the actual current falls below the programmed threshold current,

the apparatus further comprising means for testing whether the wrong kind of part has been detected, the testing means being substantially simultaneously operable while the apparatus is counting parts, the testing means including means for measuring the current in the detector when a part is present, and for comparing the current drop with a predetermined value, the latter value being called the "wrong part" threshold, and means for halting the counting if the current in the detector lies between the "wrong part" threshold and the programmed threshold.

23. Apparatus for counting a plurality of parts, comprising:

(a) means for directing said parts between a source of radiation and a detector of said radiation, so as to detect the presence of a part by sensing the amount of radiation received by the detector,

(b) programmable means for storing a value related to the level of current in the detector which must be observed in order to record a count, said level of current being called the programmed threshold current, and

(c) means for comparing the stored value with the actual current flowing through the detector, and for recording a count when the actual current falls below the programmed threshold current,

the apparatus further comprising means for testing whether more than one part has blocked radiation entering the detector, the testing means including means for determining whether the current in the detector has fallen below the level that would be due to the presence of only one part, the testing means being substantially simultaneously operable while the apparatus is counting parts.

24. Apparatus for counting a plurality of parts, comprising:

(a) means for directing said parts between a source of radiation and a detector of said radiation, so as to detect the presence of a part by sensing the amount of radiation received by the detector,

(b) programmable means for storing a value related to the level of current in the detector which must be observed in order to record a count, said level of current being called the programmed threshold current, and

(c) means for comparing the stored value with the actual current flowing through the detector, and for recording a count when the actual current falls below the programmed threshold current,

the apparatus further comprising means for determining whether the detector is open-circuited or short-circuited, and whether the wrong type of part is present, and whether a single count should be recorded as two counts due to the level to which the current in the detector falls, said determining means being substantially simultaneously operable while the apparatus is counting parts.

25. Apparatus for counting a plurality of parts, comprising:

(a) means for directing said parts between a source of radiation and a detector of said radiation, so as to detect the presence of a part by sensing the amount of radiation received by the detector,

(b) programmable means for storing a value related to the level of current in the detector which must be observed in order to record a count, said level of current being called the programmed threshold current, and

(c) means for comparing the stored value with the actual current flowing through the detector, and for recording a count when the actual current falls below the programmed threshold current,

the apparatus further comprising means for deactivating the comparing and recording means for an adjustable time interval beginning with the moment that the detector current first falls below the programmed threshold, said interval being adjusted in accordance with the length of the parts being counted, wherein the apparatus counts a given part only one time.

26. The apparatus of claim 25, further comprising automatic means for determining and setting said time interval when a plurality of parts passes the detector.

27. Apparatus for counting a plurality of parts, comprising:

(a) means for directing said parts between a source of radiation and a detector of said radiation, so as to detect the presence of a part by sensing the amount of radiation received by the detector,

(b) programmable means for storing a value related to the level of current in the detector which must be observed in order to record a count, said level of current being called the programmed threshold current, and

(c) means for comparing the stored value with the actual current flowing through the detector, and for recording a count when the actual current falls below the programmed threshold current,

the apparatus further comprising means for measuring the current in the detector when the apparatus is turned on, and for comparing the latter current with the corresponding value for a previous day.

28. A method of counting parts, comprising the steps of:

(a) determining whether a part is present by passing the part between a source of radiation and a detector, observing a change in current through the detector due to the blockage of radiation, and recording a count when the current in the detector falls below a programmed threshold,

(b) setting a timer, the timer being programmed to wait for a predetermined time interval, the interval being based on the length of the parts being counted, and

(c) resuming the counting only after the delay timer has reached the end of the predetermined interval,

wherein the timer-setting step comprises the step of setting a value stored in a microprocessor, the microprocessor being programmed to ignore signals from the detector until the predetermined interval has elapsed.

29. A method of counting parts, comprising the step of determining whether a part is present by passing the part between a source of radiation and a detector, and observing a change in current through the detector due to the blockage of radiation, the observing step including the step of comparing the current flowing through the detector with a previously stored value of a programmed threshold current, and recording a count when the current level in the detector falls below the programmed threshold level,

wherein the value of the threshold current is stored in a microprocessor, and wherein the comparing step includes comparing a signal, supplied by the microprocessor, to a signal generated by the detector.

30. A method of counting parts, comprising the step of determining whether a part is present by passing the part between a source of radiation and a detector, observing a change in current through the detector due to the blockage of radiation, and recording a count when the current level in the detector falls below a programmed threshold level, the method also comprising the step of performing at least one diagnostic test on the detector while the counting is being performed,

wherein the diagnostic test includes testing for an open-circuited condition in the detector, and wherein the testing step comprises the step of determining whether the voltage at the detector has increased beyond a predetermined level.

31. The method of claim 50, wherein the detector is connected to an operational amplifier, and wherein the determining step includes the step of determining whether the output of the operational amplifier has fallen below a predetermined value.

32. A method of counting parts, comprising the step of determining whether a part is present by passing the part between a source of radiation and a detector, observing a change in current through the detector due to the blockage of radiation, and recording a count when the current level in the detector falls below a programmed threshold level, the method also comprising the step of performing at least one diagnostic test on the detector while the counting is being performed,

wherein the diagnostic test includes testing for a short-circuited condition in the detector, wherein the detector is connected to an operational amplifier, and wherein the testing step includes the step of determining whether the output of the operational amplifier has become too high.

33. A method of counting parts, comprising the step of determining whether a part is present by passing the part between a source of radiation and a detector, observing a change in current through the detector due to the blockage of radiation, and recording a count when the current level in the detector falls below a programmed threshold level, the method also comprising the step of performing at least one diagnostic test on the detector while the counting is being performed,

wherein the diagnostic test includes determining whether the level of current in the detector is inconsistent with the type of part being counted, and wherein the determining step includes the steps of establishing a second threshold level, the second threshold level being different from the programmed threshold, and determining whether the current in the detector lies between the programmed threshold and the second threshold.

34. Apparatus for counting a plurality of parts, comprising:

(a) means for directing said parts between a source of radiation and a detector of said radiation, so as to detect the presence of a part by sensing the amount of radiation received by the detector,

(b) programmable means for storing a value related to the level of current in the detector which must be observed in order to record a count, said level of current being called the programmed threshold current, and

(c) means for comparing the stored value with the actual current flowing through the detector, and for recording a count when the actual current falls below the programmed threshold current,

the apparatus further comprising means for testing whether the detector has become open-circuited, the testing means being substantially simultaneously operable while the apparatus is counting parts, the testing means also being substantially independent of the count-recording means.

35. Apparatus for counting a plurality of parts, comprising:

(c) means for directing said parts between a source of radiation and a detector of said radiation, so as to detect the presence of a part by sensing the amount of radiation received by the detector,

(b) programmable means for storing a value related to the level of current in the detector which must be observed in order to record a count, said level of current being called the programmed threshold current, and

(c) means for comparing the stored value with the actual current flowing through the detector, and for recording a count when the actual current falls below the programmed threshold current,

the apparatus further comprising means for testing whether the detector has become short-circuited, the testing means being substantially simultaneously operable while the apparatus is counting parts, the testing means also being substantially independent of the count-recording means.