Discrete tablet counting machine

• US 5,774,518 A
• Filed: 01/30/1997
• Issued: 06/30/1998
• Est. Priority Date: 01/30/1997
• Status: Expired due to Fees

• Current Assignee: John Kirby
• Original Assignee: John Kirby
• Inventors: Kirby, John
• Primary Examiner(s): Wambach, Margaret Rose
• Application Number:
  US08/791,288
• Time in Patent Office: 516 Days
• Field of Search: 377/6, 377/7
• US Class Current: 377/6
• CPC Class Codes: G06M 1/101 by electro-optical means
• CPC Class Codes: G06M 11/00 Counting of objects distributed at random, e.g. on a surface

Abstract

A machine for counting discrete articles, such as tablets, pills, or capsules, comprising a feeder including a hopper for receiving and dispersing a plurality of tablets to be counted into separate streams, a plurality of detectors associated with each stream for detecting each tablet in that stream, a counter coupled to said plurality of counters for counting the total number of tablets in all of the streams and a switching device coupled to each of said plurality of detectors for preventing detector saturation and delay, thereby improving counter accuracy and speed.

Claims

1. A machine for counting discrete tablets, comprising:

a feeder including a hopper for receiving a plurality of tablets and means for dispersing a flow of tablets to be counted approximately evenly among a plurality of channels, each channel having a falling stream;

a plurality of detectors individually associated with each channel for detecting each of the tablets passing down each falling stream and generating a detect signal which varies as discrete tablets passing down each stream interrupt a beam of light from a light source to the respective receiver;

a plurality of detecting circuits, each detecting circuit individually coupled to a respective detector to receive the detect signal therefrom and produce a detector output signal;

a counter coupled to said plurality of detecting circuits for counting the detector output signals for the total number of tablets in all of the streams; and

a switching device coupled to each of said plurality of detecting circuits to limit detector saturation and tablet under-counting.

2. A machine for counting discrete tablets according to claim 1 wherein each of said detecting circuits comprises:

an amplifier circuit having an input coupled to the respective detector; and

each switching device includes an inverter with hysteresis coupled to said amplifier circuit for providing detecting circuit noise immunity and decreasing tablet over-counting; and

a resistor coupled between said amplifier circuit and said inverter to provide greater noise margin than if the amplifier had been directly coupled to the inverter by limiting current input to said inverter.

3. A machine for counting discrete tablets according to claim 2 wherein said inverter with hysteresis is a schmidt trigger inverter.

4. A machine for counting discrete tablets according to claim 1 wherein the switching device is a zener diode.

5. A machine for counting discrete tablets according to claim 1 wherein said counter comprises a logic circuit having a plurality of inputs individually coupled to a respective detector and generating a counter signal representing the logical-OR of the individual detect signals.

6. A machine for counting discrete tablets according to claim 5 wherein said logic circuit comprises a plurality of diodes.

7. A machine for counting discrete tablets, comprising:

a feeder including a hoper for receiving a plurality of tablets and means for dispersing a flow of tablets to be counted substantially evenly among a plurality of channels, each channel having a falling stream;

a plurality of detectors individually associated with each falling stream for detecting each of the tablets passing down each stream, each of said plurality of detectors coupled to a detector voltage supply;

a counter coupled to said plurality of detectors for counting the total number of tablets in all of the streams;

a plurality of detecting circuits individually coupled to each of said plurality of detectors and generating a tablet detect signal for each of the tablets in each of the channels;

a switching device coupled to each of said plurality of detecting circuits for preventing detecting circuit response delay and saturation; and

a device with hysteresis coupled to said plurality of detecting circuits for providing detecting circuit noise immunity.

8. A machine for counting discrete tablets according to claim 7 wherein said inverter with hysteresis is a schmidt trigger inverter.

9. A machine for counting discrete tablets according to claim 7 wherein the switching device is a zener diode.

10. A machine for counting discrete tablets according to claim 7 said counter comprises a logic circuit having a plurality of inputs individually coupled to a respective detector and generating a counter signal representing the logical-OR of the individual tablet detect signals.

11. A machine for counting discrete tablets according to claim 10 wherein said logic circuit comprises a plurality of diodes.

12. A method of counting discrete tablets with a high level of accuracy and improved speed, which comprises:

receiving a plurality of tablets to be counted in a hopper;

dispersing the plurality of tablets received substantially evenly among a plurality of channels, each channel having a stream;

producing a voltage signal for each of the tablets passing down each falling stream;

amplifying the voltage signal produced using an operational amplifier; and

clamping the amplified voltage signal produced below a voltage level corresponding to the voltage level at which the operational amplifier circuit saturates; and

counting the total number of voltage signals produced for all of the tablets passing down all streams.

13. A method of counting discrete tablets with a high level of accuracy and improved speed according to claim 12 further comprises providing the amplified voltage signal with hysteresis for improving electrical signal noise immunity.

14. A method of counting discrete tablets with a high level of accuracy and improved speed according to claim 13 wherein providing the amplified voltage signal with hysteresis is accomplished using a schmidt trigger inverter.

15. A method of counting discrete tablets with a high level of accuracy and improved speed according to claim 14 wherein clamping the amplified voltage signal is accomplished using a zener diode.