RF inventory system

• US 6,927,692 B1
• Filed: 09/05/2002
• Issued: 08/09/2005
• Est. Priority Date: 09/05/2002
• Status: Active Grant

• Current Assignee: American Greetings Corporation
• Original Assignee: American Greetings Corporation
• Inventors: Petrinovic, Peter
• Primary Examiner(s): Hofsass, Jeffery
• Assistant Examiner(s): PHAM, LAM P
• Application Number:
  US10/235,619
• Time in Patent Office: 1,069 Days
• Field of Search: 340/572.1, 340/10.3, 340/825.5, 340/568.1, 340/825.35, 340/825.49, 340/825.54
• US Class Current: 340/572.1
• CPC Class Codes: G06K 17/00 Methods or arrangements for effecting co-operative working between equipments covered by two or more of main groups G06K1/00 - G06K15/00, e.g. automatic card files incorporating conveying and reading operations

Abstract

A system and method for calculating a quantity of items wherein each item has a tag attached to it. A low intensity RF signal is radiated, causing each tag to generate a reflected signal. The frequency response of the reflected signals is then measured, and the quantity of tagged items is calculated based on the frequency response of the reflected signals.

Claims

1. A method for calculating inventory, comprising:

attaching a one bit tag to each of a plurality of items to be inventoried at a storage location;

transmitting a signal that interacts with the tag of each item present at the storage location;

receiving a one-bit frequency modulated signal resulting from the interaction between the signal and each of the one bit tags; and

calculating the quantity of items present at the storage location by correlating the frequency modulated signal with a corresponding quantity count.

2. The method of claim 1, wherein the correlating step further comprises measuring a frequency of the modulated signal at a time when the amplitude of the modulated signal is maximized.

3. The method of claim 1 further comprising the step of transmitting the quantity to a remote location.

4. The method according to claim 1, wherein the step of attaching a one-bit tag comprises the step of:

attaching a substantially identical one-bit tag to each of a plurality of different items stored at a plurality of separate storage locations.

5. The method according to claim 3, wherein the step of transmitting a signal comprises the steps of:

selecting a desired storage location at which the inventory is to be calculated; and

transmitting the signal to interact with the tag of each item present at the selected storage location with minimal interaction with tags adjacent to the storage location.

6. The method according to claim 5, further comprising the step of calculating quantity from plurality of separate storage of separate storage.

7. A system for monitoring a quantity of items stored at a storage location, the system comprising:

a tag to be coupled to each item to be counted;

a signal generator for generating an interrogation signal;

an antenna dedicated to the storage location for transmitting the interrogation signal to interact with the tag coupled to each item present at the storage location;

a receiver for receiving a secondary signal emitted in response to the frequency modulated interaction between the interrogation signal and the tags present at the storage location when the interrogation signal is transmitted; and

a computing component comprising computer-readable instructions stored in a computer-readable memory for computing the quantity of items present at the storage location by correlating the frequency modulated secondary signal with a corresponding quantity count.

8. The system according to claim 7, wherein the tags to be coupled to the items at the storage location are substantially identical and are independent of the type of the items.

9. The system according to claim 7, wherein the interrogation signal is a radio-frequency signal that interacts with tags present at the storage location to which the antenna is dedicated and has a suitably-low intensity to minimize interaction of the interrogation signal with adjacent tags not present at the storage location.

10. The system according to claim 7, wherein the secondary signal is a reflected portion of the interrogation signal.

11. The system according to claim 7, wherein the computing component computes the quantity of items present at the storage location based on a modulated frequency spectrum of the secondary signal.

12. The system according to claim 7 further comprising a look-up table stored in the computer-readable memory to be used by the computing component for computing the quantity of items present at the storage location based on the received secondary signal.

13. The system according to claim 7, wherein the antenna dedicated to the storage location substantially continuously transmits the interrogation signal to compute the real-time quantity of items present at the storage location.