Removable media spindle and antenna assembly for printer

A removable spindle for use in a thermal transfer printer houses dual RFID reader antennas that are used to read an RFID tag attached to the core of the print media. The information provided by the RFID tag enables the printer to self-calibrate based on the type of media loaded. The antenna design eliminates “null” areas at which the tag cannot be read, and enables the tag to be read around and across the entire length of the printer spindle. The design also allows the media holder to be easily removed from the printer.

CROSS-REFERENCE TO RELATED APPLICATION

Not applicable.

FIELD OF THE INVENTION

The field of the present invention is printer systems, and more particularly antenna systems for use in a auto-configurable printer.

BACKGROUND

The set up and calibration of thermal transfer printers can be both cumbersome and expensive. In most thermal transfer printers, full calibration requires feeding several feet of label stock and ribbon material. This calibration process must be performed each time a different type of media is loaded into the printer. The set up and calibration process can be avoided if the printer can discern what type of media is loaded.

To simplify printer set-up, various methods have been used to identify the media loaded into a thermal transfer printer, including touch cell memory components and barcodes. In these applications, a code or memory component including media identification data is coupled to the media provided in the printer. The data is read when the media is positioned in the printer, and the printer is configured for the appropriate media.

One method that is particularly well-suited for identifying media in a thermal transfer printer is radiofrequency identification or RFID technology. Unlike barcode or touch cell memory applications, RFID does not require either a line of sight or a direct connection to the identifying code or memory component to acquire data about the media loaded into the printer.

Antenna systems used in these types of printers for reading the data from the RFID tags, however, typically comprise a single horizontal coil or loop antenna housed in the media spindle of the printer. When the RFID transponder travels around the circumference of such an antenna, there are null areas at which the RFID reader cannot download information from the RFID transponder associated with the tag. These null areas occur when the RFID tags are perpendicular to the plane of the antenna, and, although the width of the null areas can be varied, they can never be eliminated. These nulls create problems if the printer attempts to gather information from the RFID transponder while the transponder is located in a null. This problem is particularly troublesome when the media is initially loaded into the printer, and when it is important to verify the type of media inserted into the printer.

The present invention addresses these problems.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides an antenna system for use in a printer system. In this antenna configuration, two coil or loop antennas are located in a media spindle of a printer. A controller in the printer switches the RFID reader between two antennas when it fails to receive a signal from the antenna that is being polled. When the RFID transponder is located in a null area for one antenna, for example, the reader will switch to the opposing antenna, which will be in an optimum orientation relative to the transponder. Whenever the RFID transponder is located in a null of one reader antenna, the opposing antenna will always be in an optimum orientation. The control system therefore compensates for nulls and allows the reader to successfully download information from and upload information to the transponder in any position along or around the circumference of the printer media spindle.

The antenna system of the present invention, moreover, is easily positioned in and removed from the printer. In one embodiment, the media spindle utilizes spring-loaded contact pins which are mounted on printed circuit boards coupled to the antennas in the antenna system. These circuit boards are connected to the antenna circuit boards via coaxial cable, and the resulting antenna assembly is located within the media holder housing.

When the media holder assembly is installed into the printer housing, the spring pins or contacts can make electrical connection with corresponding round, flat button contacts in the receptacle for the media holder in the printer housing, with the loading of the springs inside the media holder contact pins providing consistent electrical contact. To ensure long life for the spring contact pins, and to prevent forces acting on the pins in directions other than that of spring actuation, the media holder housing is designed to fit very closely into the receptacles in the printer housing. The close fit prevents lateral movement of the contact pins along the surface of the contact buttons. Furthermore, the spring contact pins are located below flush in the media holder housing. Therefore, when the media holder is not installed into the printer, the pins are protected from damage by the media holder housing.

In another aspect of the invention, a printer is provided with an RF transceiver and an antenna assembly sized and dimensioned to be received in the interior of a core of a roll of media including at least one RFID tag. The antenna assembly comprises a first antenna and a second antenna, and the first antenna is positioned with respect to the second antenna to allow the RF transceiver to acquire data from the RFID tag from the other of the first and second antennas when a selected one of the first and second antennas is in a null area for data communications from the RFID tag. A controller is connected to the RF transceiver, and is programmed to switch between the first and second antennas to avoid the null area.

In yet another aspect of the invention, a printer includes a housing, a printer circuit, and a removable spindle. The housing includes a receptacle, and the printer circuit is positioned in the housing, and includes an RF transceiver coupled to the receptacle through a switch. The removable spindle includes an antenna assembly comprising a first and a second antenna to provide a communication link to the RF transceiver, and an antenna connector that is receivable in the receptacle for connection to the printer circuit. The printer circuit further includes a controller for selectively coupling the RF transceiver to one of the first and second antennas to allow the printer circuit to communicate to an RFID tag on a roll of media provided on the removable spindle.

In still another aspect of the invention, a spindle for retaining a roll of media in a printer is provided. The spindle includes a first and a second planar antenna, in which the second planar antenna is positioned with respect to the first planar antenna to provide communications to an RF transceiver in the printer when the first planar antenna is in a null area.

These and other aspects of the invention will become apparent from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention and reference is made therefore, to the claims herein for interpreting the scope of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the figures and more particularly toFIG. 1, a printer10including a printer housing11having a printer housing base12is shown. Referring now also toFIG. 2, the printer housing base12is sized and dimensioned to receive a print head (not shown) and associated circuitry for printing information, such as text, on a media provided in a media holder assembly14.

Referring still toFIG. 2, the printer housing base12includes media holder receptacles32which are formed as depressions in on opposing sides of the printer housing base12, and which are sized and dimensioned to receive a media holder plug27provided in the media holder assembly14. The interconnection between the plug27and receptacle32provides an electrical connection between the media holder assembly14and printer housing12as described more fully below.

Referring now toFIG. 3, an exploded view of the media holder assembly14is shown. The media holder assembly14includes a media holder base30, which includes media holder plugs27extending from opposing sides. The media holder base30is sized and dimensioned to receive an antenna assembly22which, referring now also toFIG. 4, includes a first antenna21and a second antenna23which, as shown here, can be substantially planar in construction. Referring now also toFIG. 10, each of the antennas21and23is preferably constructed on a printed circuit board that includes a trace52that extends around the perimeter of the printed circuit board, forming a loop. As shown, the antennas21and23are substantially orthogonal to one another, that is, the antennas are positioned substantially 90 degrees apart. However, the antenna assembly22can include two or more antennas that are positioned with respect to one another to allow the antennas to be electrically switched to compensate for nulls encountered by any one of the antennas in the antenna assembly22, as described below. The antennas, therefore, can be varied in number and provided at different angles, depending on the width of the null area, and other factors.

Referring still toFIGS. 3 and 10, each of the antennas21and23further includes a printed circuit board24mounted to the antenna printed circuit board, and that includes contact pins26that are connected to the loop52of the corresponding antenna21or23. A coaxial cable28connects the antenna printed circuit board21or23to the contact pins26. The contact pins26are preferably spring-loaded contacts, which provide a good electrical connection to receptacle32, as discussed below. Although pins are described here, the antenna connector can also be sockets or other types of connectors.

Referring now toFIG. 5, the media holder plugs27formed in the media holder base30include depressions provided in a bottom surface of the plugs27. The depressions27are sized and dimensioned to receive the contact pins26. As received in the plug27, the contact pins26rest in the depression29formed in the bottom surface of the plug27, and do not protrude from the media holder14. The depression29therefore protects the contact pins26from being bent in directions other than that of spring actuation, preventing bending, tearing, shearing, or other damage to the contact pins26.

Referring now also toFIG. 6, as discussed above, the printer housing12includes a media holder receptacle32that houses electrical connectors for interconnection with the plug27. As shown here, the connectors can be button contacts34, which are round and flat and therefore provide a consistent electrical connection between the contact pins26and the button contacts34, particularly where the contact pins26are spring-loaded contacts. Depending on the construction of the contact pins26, however, various types of connectors can be provided in the receptacle32, including pins, sockets, or other connectors. Furthermore, the orientation of the plug27and receptacle32can be reversed, and various other modifications made to the interconnection between the media holder base30and housing12.

Referring now also toFIG. 7, a cutaway view of the media holder14as received in the printer housing12is shown, illustrating particularly the interconnection between the receptacle32and plug27. As shown here, the plug27is received in the receptacle32in a tight, interference fit. When the plug27is inserted into the receptacle32, the contacts pins26are aligned with and rest on the button contacts or pads34. As described above, the contact pins26are preferably spring loaded and therefore provides a good electrical connection to the button contacts or pads34. The contact pins26are connected directly to the spring contact PC board24which, as described above, is connected to an antenna21or23. A coaxial cable36connects the button contacts34to internal printer circuitry, described below with reference toFIG. 9.

Referring now toFIG. 9, a block diagram of a printer circuit for use in a printer employing the present invention is shown. The printer includes a printer control circuit40which, as described above, can control communications between RFID tags as provided on a roll of media and on a ribbon inserted into the printer. The printer control circuit40includes a microprocessor42or other controller element, an RF transceiver44for communicating with RFID tags and transponders, and one or more RF switches46and48, for switching between antennas. The printer control circuit40can also control a print head (not shown) to drive the print head to print on the printer media, although a separate circuit can also be provided for this function.

Referring still toFIG. 9, in operation, the control circuit40is programmed to select between antennas21and23through RF switch48based on whether data can be received from the selected antenna. The output of the media antenna is fed through switch48to an RF transceiver44which provides information acquired from the RFID tags or transponders associated with the media antennas21and23to the microprocessor42. Referring now toFIG. 8, the cutaway side view of the media roll as positioned on the antenna assembly22is shown. To provide data to the printer, an RFID transponder18is coupled to the interior of a media core16associated with the media. The transponder18includes a memory component which stores data indicating the type of media that is provided on the core16. This information can include, for example label material type, height and width of printable area, label color, correlating acceptable ribbons, etc.

Referring again toFIG. 9, optionally, a second antenna50can be provided to read from and write to an RFID tag or transponder associated with the ribbon inserted into the printer prior to a printing process. The ribbon antenna50is connected to the microprocessor42selectively through the RF switch46which, as shown, is also controlled by the microprocessor42to select input from one of the media antennas21or23or the ribbon antenna50. Referring now also toFIG. 11, the ribbon antenna50is provided on a circuit board, which includes a trace54in the form of a loop or coil.

Referring now toFIG. 8, in operation, a roll of printer media17is positioned on the media holder assembly14. The roll of media17includes a media core16to which an RFID tag or transponder18is coupled. The RFID transponder18stores data about the type of media that is being positioned in the printer10. The roll of media17is positioned over the spindle or antenna assembly22, such that the antennas21and23are substantially centered in the media core16. When the media17is properly positioned, the media holder assembly14is plugged into the receptacles32in the printer housing12, providing a connection between the contact pins26and contact buttons34, as shown inFIG. 7.

Referring again toFIG. 8and also toFIG. 9, null areas, where a corresponding antenna cannot access an RFID tag18, are located directly above the wires or traces that form the coil antennas21and23on the printed circuit boards that form antennas21and23, and can prevent the printer circuit40from reading the data from the RFID transponder18when the transponder18is located at a null, which can be particularly troublesome when the media is initially loaded into the printer. To allow the RFID transponder18to be read irrespective of its position, the printer control circuit40, and particularly microprocessor42, selectively activates the RF transceiver44to acquire data from the RF tag18, and activates switch48to query the RFID tag18via either antenna21or antenna23. The microprocessor switches antennas if it cannot read data from the RFID tag18using the connected antenna21or23, which provides an indication that the RFID tag18is in a null area. As described above, the microprocessor42can also selectively switch antenna50into the print control circuit40to read data associated with an RFID tag associated with the ribbon, which can then be used to determine operating characteristics for the printer, or to assure a match between the print media and ribbon.

It should be understood that the methods and apparatuses described above are only exemplary and do not limit the scope of the invention, and that various modifications could be made by those skilled in the art that would fall under the scope of the invention. For example, although specific types of connectors are described above for coupling the antenna system to the printer, it will be apparent that various other types of known plug and receptacle elements can be used, and various types of electrical contacts can also be used. Additionally, although the invention is described above as including two antennas that are substantially orthogonal, it will be apparent that more than two antennas could be used. Furthermore, these antennas could be arranged with respect to one another in a number of ways to allow for reading of data when the RFID tag is in a null area associated with any one antenna. Additionally, although the invention is described above specifically with reference to a thermal transfer printer, the present invention can be used in various types of printers and other types of equipment where rolls are used in conjunction with RFID transponders or tags.