Antenna for mobile wireless data collection system

• US 7,656,296 B2
• Filed: 04/13/2006
• Issued: 02/02/2010
• Est. Priority Date: 05/13/2005
• Status: Active Grant

• Current Assignee: EMS Technologies, Inc. (Honeywell International Inc.)
• Original Assignee: EMS Technologies, Inc. (Honeywell International Inc.)
• Inventors: Sorenson, Richard W. Jr., Roeder, William H., Runyon, Donald L.
• Primary Examiner(s): Previl; Daniel
• Application Number:
  US11/402,798
• Publication Number:
  US 20060255948A1
• Time in Patent Office: 1,391 Days
• Field of Search: 3405721-5729, 340/10.1, 340/10.52, 340/539.2, 340/539.11, 340/539.13, 235384-385, 705/22, 705/28, 705/29
• US Class Current: 340/572.7
• CPC Class Codes: B62B 5/0096 Identification of the cart or merchandise, e.g. by barcodes or radio frequency identification [RFID]
• CPC Class Codes: B66F 9/0755 Position control; Position detectors
• CPC Class Codes: G06Q 10/08 Logistics, e.g. warehousing, loading or distribution; Inventory or stock management
• CPC Class Codes: H01Q 1/2208 associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems methods or arrangements for sensing record carriers, e.g. for reading patterns G06K7/00; record carrier for use with machines and with at least a part designed to carry digital markings G06K19/00
• CPC Class Codes: H01Q 13/085 Slot-line radiating ends

Abstract

The present invention provides an antenna system for reading RFID tags and/or transmitting and receiving wireless network signals, including for example wireless local area network (WLAN) signals, in a material handling environment. A ruggedized antenna can be mounted on the load backrest of a lift truck and configured to accomplish the reading of RFID tags that indicate particular pallet storage locations and the reading of RFID tags that indicate warehouse locations, such as specific loading docks. The antenna system can also be configured to accomplish transmitting and receiving WLAN signals for communication with a warehouse.

Claims

1. An antenna element for use on the load backrest of a lift truck, comprising:

a radiating element of conducting material having a substantially uniform voltage distribution across the radiating element at low frequency; and

a radio frequency feed line, the feed line being coupled across an opening in the radiating element, wherein the radiating element is affixed to a portion of said load backrest so as to project at least one radio frequency signal in an essentially upward direction.

2. The antenna element of claim 1, wherein the radiating element is configured for mounting on the load backrest so as not to protrude into a plane of a load area of the lift truck.

3. The antenna element of claim 1, wherein said radiating element is affixed to the load backrest by at least one of welding, clamping, bolting and tongue-in-groove mounting.

4. The antenna element of claim 1, wherein the radiating element is a planar element and the opening of said planar radiating element is a notch formed therein and said feed line is coupled across the notch.

5. The antenna element of claim 4, wherein the material of the planar radiating element is at least one-eighth inch (⅛

″

) thick steel.

6. The antenna element of claim 4, wherein the planar radiating element includes cutouts.

7. The antenna element of claim 4, wherein the feed line is coupled to an opening to project and/or receive a signal for communication with a wireless network.

8. The antenna element of claim 7, wherein said signal is transmitted over an IEEE standard 802.11 wireless network.

9. The antenna element of claim 7, wherein said planar radiating element has a second notch and a second feed line, and wherein each feed line coupled across each of the notches is for a wireless network.

10. The antenna element of claim 4, wherein the feed line is adapted for a RFID tag reader, wherein the radio frequency signal is projected from the notch in a generally upward direction.

11. The antenna element of claim 10, wherein said planar radiating element has a second notch, the first and second notches being coupled to form an array.

12. The antenna element of claim 11, wherein the first and second notches are flared notches and the effective read zone of said projected radio frequency signal is limited to essentially the width of a dock door.

13. The antenna element of claim 10, wherein the projected radio frequency signal has a major lobe with a transverse cross-section that has a ratio of major to minor dimensions greater than or equal to 2.

14. The antenna element of claim 10, wherein at least a second feed line is coupled to a second opening to project and/or receive a signal for communication with a wireless network.

15. The antenna element of claim 4, wherein the planar radiating element comprises a first and a second notch, the first and the second flared notch coupled to a feed line adapted for a RFID tag reader, and further comprising a third opening, the third opening coupled to a feed line adapted to transmit and/or receive a wireless network signal.

16. The antenna element of claim 1, wherein the antenna element is uncovered.

17. The antenna element of claim 1, wherein the antenna element is uncovered.

18. A load backrest for a lift truck, comprising:

a frame adapted for connection to an lift carriage and extending in a generally vertical plane above the carriage; and

an antenna configured to have substantially uniform voltage distribution across the radiating element at low frequency and to be in essentially the same vertical plane as said frame, said antenna having a radiating element of conducting material with at least one opening, said radiating element configured to project at least one radio frequency signal.

19. The load backrest of claim 18, wherein said frame further comprises a mounting bracket to receive said antenna.

20. The load backrest of claim 18, wherein the radiating element is configured for mounting on the load backrest so as not to protrude into a plane of a load area of the lift truck.

21. The load backrest of claim 18, wherein the radiating element is a planar element and the opening of said planar radiating element is at least one notch formed therein.

22. The load backrest of claim 21, wherein the planar radiating element includes cutouts.

23. The load backrest of claim 21, further comprising at least one feed line coupled to the opening to project or receive a signal.

24. The load backrest of claim 23, wherein said signal is an wireless network signal for communication with a warehouse management system.

25. The load backrest of claim 23, wherein said opening is a notch and said signal is for a RFID tag reader.

26. The load backrest of claim 25, wherein the projected signal at half power has a major lobe with a transverse cross-section that has a ratio of major to minor dimensions greater than or equal to 2.

27. The load backrest of claim 26, further comprising at least a second feed line coupled to a second opening to project or receive a wireless network signal for communication with a warehouse management system.

28. A data collection system for a powered industrial truck with a lift carriage, said system comprising:

a load backrest mounted to said lift carriage, said load backrest including an integrated antenna with a radiating element configured to have substantially uniform voltage distribution across the radiating element at low frequency and having an opening configured for projecting at least one radio frequency signal;

a feed line coupled to the opening to communicate a signal for reading a RFID tag;

a RFID tag reading system including a RFID radio and a CPU; and

a power source for said reader and said antenna.

29. The data collection system of claim 28, further comprising a second feed line coupled to a second opening to communicate a signal for a wireless network, and wherein said reader further includes a wireless network radio.

30. The data collection system of claim 28, wherein the second one of the openings is vertical slot for communicating over an 802.11 network.

31. The data collection system of claim 28, wherein the opening is a flared notch to project the signal in a predominantly upward direction.

32. A method of collecting inventory tracking data in material handling environment, said method comprising the steps of:

providing location RFID tags in an inventory storage area, wherein the location RFID tags represent unique location in the inventory storage area;

providing product RFID tags on the inventory, wherein the product RFID tags represent inventory contents;

reading information from the location RFID tags and the product RFID tags using an RF signal transmitted from an antenna having a radiating element on a load backrest of a lift carriage and having a substantially uniform voltage distribution across the radiating element at low frequency; and

communicating the RFID tag information to an inventory management system.

33. The method of claim 32, wherein the signal transmitted from the antenna is a RF signal that has, at half power, a major lobe with a transverse cross-section that has a ratio of major to minor dimensions greater than or equal to 2.

34. The method of claim 32, wherein the step of communicating the RFID tag information is conducted using a wireless network antenna co-located on the radiating element to send a second RF signal.

35. The method of claim 32, wherein the radiating element is configured to project the RF signal transmitted from the antenna in a predominantly upward direction.

36. The method of claim 32, wherein said antenna has a linear polarization aligned with the primary plane of the load backrest.

37. A method for reading an overhead RFID tag using an antenna mounted on a lift truck, comprising:

projecting in a predominantly upward direction a first RF signal having, at half power, a major lobe with a transverse cross-section having a ratio of major to minor dimensions greater than or equal to 2, wherein said lift truck includes a front, a back, a first side, and a second side, and wherein said major dimension is parallel to a direction extending from the front of said lift truck to the back of said lift truck, and wherein said minor dimension is parallel to a direction extending from the first side of said lift truck to the second side of said lift truck;

receiving a second signal from the RFID tag; and

transmitting the second signal to a RFID reader.

38. The method of claim 37, wherein said antenna has a radiating element having a substantially uniform voltage distribution across the radiating element at low frequency.

39. The method of claim 37, wherein information about the second signal is transmitted to an inventory management system using a wireless network antenna co-located on the radiating element.

40. The method of claim 37, wherein the antenna has an adjustable power level and the power level is adjusted to allow for accurate RFID tag reading in different applications.

41. A RFID antenna for a lift truck, comprising:

a planar radiating element on an essentially-vertically-oriented load backrest, said radiating element oriented transverse to the primary direction of travel of said lift truck,

said radiating element having a substantially uniform voltage distribution across the radiating element at low frequency, and

said antenna having a linear polarization aligned with the primary plane of the load back rest and is configured for projecting an electromagnetic signal in predominantly an upward direction.

42. The antenna element of claim 41, wherein the radiating element is configured on the load backrest so as not to protrude into a plane of a load area of the lift truck.

43. The antenna element of claim 41, wherein said element is affixed to the load backrest by at least one of welding, bolting and tongue-in-groove mounting.

44. A WLAN antenna for a lift truck, comprising:

a planar radiating element on an essentially-vertically-oriented load backrest, said radiating element oriented transverse to the primary direction of travel of said lift truck,

said radiating element having a substantially uniform voltage distribution across the radiating element at low frequency, and

said antenna having a linear polarization aligned with the primary plane of the load back rest.

45. A dual band antenna element, comprising:

a radiating element of conducting material having a substantially uniform voltage distribution across the radiating element at low frequency, said radiating element comprising a first opening and a second opening; and

a first radio frequency feed line coupled across said first opening in the radiating element, to radiate a radio frequency signal at a first frequency in essentially an upward direction;

a second radio frequency feed line coupled across said second opening in the radiating element, wherein the radiating element is configured for projecting a second radio frequency signal.

46. The antenna element of claim 45, wherein the material of the radiating element is at least one-eighth inch (⅛

″

) thick steel.

47. The antenna element of claim 45, wherein the radiating element is a planar radiating element.

48. The antenna element of claim 45, wherein the first feed line is adapted for an RFID tag reader.

49. The antenna element of claim 48, wherein the feed line is coupled to an opening to project and/or receive a signal for communication with a wireless network.

50. The antenna element of claim 45, wherein said radiating element has a third opening, the first and third openings being coupled to said first feed line to form an array.

51. The antenna element of claim 50, wherein the first and third openings are flared notches and the effective read zone of said projected radio frequency signal from said first and third openings has, at half power, a major lobe with a transverse cross-section that has a ratio of major to minor dimensions greater than or equal to 2.