Article or seed counter

• US 4,635,215 A
• Filed: 09/10/1984
• Issued: 01/06/1987
• Est. Priority Date: 09/10/1984
• Status: Expired due to Term

• Current Assignee: Deere & Company
• Original Assignee: Deere & Company
• Inventors: Friend, Kenneth D.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Laibowitz, Danielle B.
• Application Number:
  US06/649,108
• Time in Patent Office: 848 Days
• Field of Search: 364/555, 364/564, 250/221, 250/222.1, 250/222.2, 377/6, 377/10
• US Class Current: 702/128
• CPC Class Codes: A01C 7/105 Seed sensors
• CPC Class Codes: G01V 8/20 using multiple transmitters or receivers
• CPC Class Codes: G06M 1/101 by electro-optical means
• CPC Class Codes: G06M 7/00 Counting of objects carried by a conveyor

Abstract

A sensor for counting articles, such as seeds, moving through a conduit includes an array of infrared LEDs generating a uniform diffuse beam of radiation which entirely illuminates a cross sectional volume of the conduit. The beam is detected by a planar photo diode which extends across the opposite side of the conduit. A pair of mirrors extend along opposite sides of the conduit between the array and the photo diodes. Slits narrow the beam and limit the amount of radiation which can impinge upon the photo diode. The signal from the photo diode is integrated by a signal processing unit so that the sensor can count a plurality of seeds in a group of seeds which simultaneously pass through the beam. The signal processing unit automatically compensates for changes in the steady state photo-diode output and for changes in seed size.

Claims

1. A signal processor for processing a signal of an article sensor which generates a variable signal which has a relationship to the quantity of articles within the sensor, the signal processor comprising:

means for generating an offset value representing a steady state magnitude of the variable signal produced by the article sensor when no articles are in transit through the article sensor;

means for deriving a first value by subtracting an input value from the offset value, wherein the input value represents an actual magnitude of the variable signal;

means for deriving an area value by repetitively integrating the first value; and

means for comparing the area value to an estimated area value and for generating an output signal when the area value is not less than the estimated area value.

2. The article sensor of claim 1, wherein the signal processor further comprises:

means for periodically adjusting the estimated area value.

3. The article sensor of claim 1, wherein the signal processor further comprises:

means for periodically adjusting the offset value in response to changes in the steady-state magnitude of the variable signal.

4. The article sensor of claim 1, wherein the signal processor further comprises:

means for generating a quantity value indicative of the number of articles in a group of articles which makes a transit through the article sensor; and

means for periodically adjusting the estimated area value wherein the amount of adjustment varies, depending upon the quantity value.

5. In an article sensor having an article flow path, a beam generator and a beam detector oriented so that articles in the flow path interrupt at least a part of the beam and cause the beam detector to generate a variable signal, a signal processing method comprising the following steps:

(a) obtaining a signal value derived from the variable signal by subtracting a current value of the variable signal from an offset value representing a steady state level of the variable signal;

(b) adding the signal value to a predetermined pulse value to obtain an updated pulse value;

(c) comparing the updated pulse value to a threshold value; and

(1) if the updated pulse value is less than the threshold value, repeating steps (b) and (c), otherwise;

(2) if the updated pulse value is not less than the threshold value, generating an output signal indicative of a transit of an article through the beam.

6. The signal processing method of claim 5, further comprising:

(d) upon the updated pulse value being not less than the threshold value, subtracting an estimated pulse area value from the updated pulse value to obtain a new predetermined pulse value; and

(e) repeating steps (a)-(d).

7. The signal processing method of claim 6 further comprising:

upon the updated pulse value being not less than the threshold value, incrementing a quantity value; and

modifying the estimated pulse area value, depending upon the quantity value.

8. The signal processing method of claim 6, further comprising:

upon the updated pulse value being not less than the threshold value, incrementing a quantity value;

if the quantity value has satisfied a first condition a predetermined number of times, then setting the quantity value equal to an initial quantity value before repeating steps (a)- (d);

if the quantity value repeatedly satisfied a second condition a predetermined number of times, then decreasing the estimated pulse area value and setting the quantity value to the initial quantity value before repeating steps (a)-(d); and

if the quantity value satisfies a second condition a predetermined number of times, then increasing the estimated pulse area value and setting the quantity value to the initial quantity value before repeating steps (a)-(d).

9. The signal processing method of claim 5, further comprising:

increasing the offset value by a certain amount if the signal value satisfies a first condition for a certain time period; and

decreasing the offset value by a predetermined amount if the signal value satisfies a second condition for a predetermined time period.