Seed level detection in a seed meter

1. A method of controlling a seed meter having a housing defining a seed chamber and a seed disc having seed cells defined as openings through a perimeter region of the seed disc, the method comprising:

receiving, with an electronic controller, signals from a first sensor carried by the housing and aimed at the perimeter region of the seed disc where the seed cells are defined;

receiving, with the electronic controller, signals from a second sensor carried by the housing and aimed at the seed cells in the perimeter region of the seed disc at a different location than the first sensor; and

coordinating, with the electronic controller, the sampling of signals from the first sensor with the detection of an empty seed cell based on the signals received from the second sensor.

2. The method of claim 1 , wherein the first sensor is at least partially disposed within a vacuum channel of the seed meter.

3. The method of claim 1 , wherein the seed disc defines a rotational axis that extends through a horizontal centerplane of the seed chamber, wherein the seed chamber defines a bottom end such that seeds tend to move toward the bottom end of the seed chamber due to the influence of gravity, and wherein the first sensor is aimed at a targeted portion of the perimeter region located vertically between the bottom end of the seed chamber and the horizontal centerplane of the seed chamber.

4. The method of claim 3 , wherein the first sensor is aimed at a location of the seed cell at the perigee location of the seed disc's rotation adjacent the bottom of the seed chamber.

5. The method of claim 1 , wherein the first sensor is a reflectance style sensor.

6. The method of claim 1 , wherein the second sensor is a break beam style sensor.

7. A method of controlling a seed meter having a housing defining a seed chamber and a seed disc having seed cells defined as openings through a perimeter region of the seed disc, the method comprising:

receiving, with an electronic controller, signals from a first sensor carried by the housing and aimed at, the perimeter region of the seed disc where the seed cells are defined;

receiving, with the electronic controller, signals from a second sensor carried by the housing and aimed at the seed cells in the perimeter region of the seed disc at a different location than the first sensor; and

coordinating, with the electronic controller, the sampling of signals from the first sensor with the detection of an empty seed cell based on the signals received from the second sensor,

wherein the seed disc is disposed so that at any given moment only a first portion of the seed disc is bounded within a vacuum channel of the seed meter while a second portion of the seed disc is bounded outside of the vacuum channel, and wherein the second sensor is aimed at the seed cells in the perimeter region of the seed disc in the second portion that is bounded outside of the vacuum channel.

8. The method of claim 7 , wherein the first sensor is aimed at the seed cells in the perimeter region of the seed disc in the first portion of the seed disc that is bounded within the vacuum channel.

9. The method of claim 7 , further comprising determining a frequency at which empty seed cells pass by the second sensor based on the signals received from the second sensor.

10. The method of claim 9 , wherein coordinating the sampling of signals from the first sensor comprises coordinating the sampling of signals from the first sensor based on the determined frequency.

11. The method of claim 7 , wherein the seed disc defines a rotational axis that extends through a horizontal centerplane of the seed chamber, wherein the seed chamber defines a bottom end such that seeds tend to move toward the bottom end of the seed chamber due to the influence of gravity, and wherein the first sensor is aimed at a targeted portion of the perimeter region located vertically between the bottom end of the seed chamber and the horizontal centerplane of the seed chamber.

12. The method of claim 11 , wherein the first sensor is aimed at a location of the seed cell at the perigee location of the seed disc's rotation adjacent the bottom of the seed chamber.

13. The method of claim 7 , wherein the first sensor is one of a reflectance style sensor or a break beam style sensor.

14. A method of controlling a seed meter having a housing defining a seed chamber and a seed disc having seed cells defined as openings through a perimeter region of the seed disc, the method comprising:

receiving, with an electronic controller, signals from a first sensor carried by the housing and aimed at the perimeter region of the seed disc where the seed cells are defined;

receiving, with the electronic controller, signals from a second sensor carried by the housing and aimed at the seed cells in the perimeter region of the seed disc at a different location than the first sensor;

determining a frequency at which empty seed cells pass by the second sensor based on the signals received from the second sensor

coordinating, with the electronic controller, the sampling of signals from the first sensor with the detection of an empty seed cell based on the signals received from the second sensor.

15. The method of claim 14 , wherein coordinating the sampling of signals from the first sensor comprises coordinating the sampling of signals from the first sensor based on the determined frequency.

16. The method of claim 14 , wherein the seed disc is disposed so that at any given moment only a first portion of the seed disc is bounded within a vacuum channel of the seed meter while a second portion of the seed disc is bounded outside of the vacuum channel, and wherein the second sensor is aimed at the seed cells in the perimeter region of the seed disc in the second portion that is bounded outside of the vacuum channel.

17. The method of claim 16 , wherein the first sensor is aimed at the seed cells in the perimeter region of the seed disc in the first portion of the seed disc that is bounded within the vacuum channel.

18. The method of claim 14 , wherein the first sensor is at least partially disposed within a vacuum channel of the seed meter.

19. The method of claim 14 , wherein the seed disc defines a rotational axis that extends through a horizontal centerplane of the seed chamber, wherein the seed chamber defines a bottom end such that seeds tend to move toward the bottom end of the seed chamber due to the influence of gravity, and wherein the first sensor is aimed at a targeted portion of the perimeter region located vertically between the bottom end of the seed chamber and the horizontal centerplane of the seed chamber.

20. The method of claim 19 , wherein the first sensor is aimed at a location of the seed cell at the perigee location of the seed disc's rotation adjacent the bottom of the seed chamber.

21. The method of claim 14 , wherein the first sensor is one of a reflectance style sensor or a break beam stele sensor.