Card reader device for contactless readable cards and method for operating said card reader device
First Claim
1. A method of operating a card reader to perform a separate customization sequence to improve communication between the card reader and a contactlessly readable card situated in a local area of the card reader, which comprises steps of:
- producing a radio frequency magnetic field in the local area of the card reader, a magnetic field strength of the radio frequency magnetic field is controlled in order to execute communication with the contactlessly readable card, and an information transmission from the card reader to the contactlessly readable card situated in the local area prompts an execution of amplitude shift keying modulation between two non-zero magnetic field strengths, an unmodulated magnetic field strength a and a modulated magnetic field strength b;
evaluating the radio frequency magnetic field with unmodulated magnetic field strength and the radio frequency magnetic field with modulated magnetic field strength for detecting and analyzing a variation in the radio frequency magnetic field by the contactlessly readable card situated in the local area;
evaluating the radio frequency magnetic field with the unmodulated magnetic field strength and the radio frequency magnetic field with the modulated magnetic field strength using one of a reception inductor or reception antenna, which is different than a transmission inductor or a transmission antenna that is used, to receive the radio frequency magnetic field signal with the unmodulated magnetic field strength and the radio frequency magnetic field with the modulated magnetic field strength and ascertaining a modulation index mmeasured, the modulation index mmeasured is formed as a quotient of a difference between the unmodulated magnetic field strength ameasured and the modulated magnetic field strength bmeasured and a sum of the two magnetic field strengths ameasured, bmeasured(mmeasured=(ameasured−
bmeasured)/(ameasured+bmeasured));
wherein the ameasured represents the radio frequency magnetic field with the unmodulated magnetic field strength and the bmeasured represents the radio frequency magnetic field with the modulated magnetic field strength for calculating the modulation index mmeasured using a detection circuit of the card reader and wherein the detection circuit determines the values ameasured, bmeasured representing the magnetic field strengths from the received radio frequency magnetic field signal, so that the values represent the radio frequency magnetic field strength that is averaged over time for the communication between the card reader and the contactlessly readable card;
comparing the modulation index mmeasured ascertained with a prescribed modulation index mprescribed;
customizing the magnetic field strengths when controlling a production of the radio frequency magnetic field in order to bring the modulation index mmeasured more into line with the prescribed modulation index mprescribed; and
executing the separate customization sequence iteratively which includes substeps of;
performing the amplitude shift keying between the unmodulated magnetic field strength a and the modulated magnetic field strength b, andvarying at least one of the modulated magnetic field strength or the unmodulated magnetic field strength, in each case on a basis of a comparison between the modulation index mmeasured ascertained and the prescribed modulation index mprescribed, in order to prompt the ascertained modulation index mmeasured to be brought more into line with the prescribed modulation index mprescribed.
1 Assignment
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Accused Products
Abstract
A card reader device is configured to carry out communication with a contactless readable card according to standard ISO/IEC 14443 type B. In order to provide that a modulation index, which self-adjusts in close range in a presence of a contactless readable card, corresponds to a desired specified modulation index, the magnetic field is received and evaluated via a reception antenna of the card reader device. The modulation index is controlled or regulated accordingly in case of deviations between a measured modulation index and a specified value for the modulation index in order to approximate the measured modulation index to the specified value.
45 Citations
17 Claims
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1. A method of operating a card reader to perform a separate customization sequence to improve communication between the card reader and a contactlessly readable card situated in a local area of the card reader, which comprises steps of:
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producing a radio frequency magnetic field in the local area of the card reader, a magnetic field strength of the radio frequency magnetic field is controlled in order to execute communication with the contactlessly readable card, and an information transmission from the card reader to the contactlessly readable card situated in the local area prompts an execution of amplitude shift keying modulation between two non-zero magnetic field strengths, an unmodulated magnetic field strength a and a modulated magnetic field strength b; evaluating the radio frequency magnetic field with unmodulated magnetic field strength and the radio frequency magnetic field with modulated magnetic field strength for detecting and analyzing a variation in the radio frequency magnetic field by the contactlessly readable card situated in the local area; evaluating the radio frequency magnetic field with the unmodulated magnetic field strength and the radio frequency magnetic field with the modulated magnetic field strength using one of a reception inductor or reception antenna, which is different than a transmission inductor or a transmission antenna that is used, to receive the radio frequency magnetic field signal with the unmodulated magnetic field strength and the radio frequency magnetic field with the modulated magnetic field strength and ascertaining a modulation index mmeasured, the modulation index mmeasured is formed as a quotient of a difference between the unmodulated magnetic field strength ameasured and the modulated magnetic field strength bmeasured and a sum of the two magnetic field strengths ameasured, bmeasured(mmeasured=(ameasured−
bmeasured)/(ameasured+bmeasured));
wherein the ameasured represents the radio frequency magnetic field with the unmodulated magnetic field strength and the bmeasured represents the radio frequency magnetic field with the modulated magnetic field strength for calculating the modulation index mmeasured using a detection circuit of the card reader and wherein the detection circuit determines the values ameasured, bmeasured representing the magnetic field strengths from the received radio frequency magnetic field signal, so that the values represent the radio frequency magnetic field strength that is averaged over time for the communication between the card reader and the contactlessly readable card;comparing the modulation index mmeasured ascertained with a prescribed modulation index mprescribed; customizing the magnetic field strengths when controlling a production of the radio frequency magnetic field in order to bring the modulation index mmeasured more into line with the prescribed modulation index mprescribed; and executing the separate customization sequence iteratively which includes substeps of; performing the amplitude shift keying between the unmodulated magnetic field strength a and the modulated magnetic field strength b, and varying at least one of the modulated magnetic field strength or the unmodulated magnetic field strength, in each case on a basis of a comparison between the modulation index mmeasured ascertained and the prescribed modulation index mprescribed, in order to prompt the ascertained modulation index mmeasured to be brought more into line with the prescribed modulation index mprescribed. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A card reader for performing a separate customization to improve communicating with a contactlessly readable card in a local area of the card reader, the card reader comprising:
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a controllable transmission unit for producing a radio frequency magnetic field in the local area of the card reader, a magnetic field strength of the radio frequency magnetic field can be controlled to execute communication with the contactlessly readable card, said controllable transmission unit configured to execute amplitude shift keying modulation between two non-zero magnetic field strengths, including an unmodulated magnetic field strength a and a modulated magnetic field strength b, for an information transmission from the card reader to the contactlessly readable card situated in the local area; an evaluation unit for evaluating the radio frequency magnetic field with unmodulated magnetic field strength and the radio frequency magnetic field with modulated magnetic field strength to detect and analyze a variation in the magnetic field by the contactlessly readable card situated in the local area; a reception unit selected from the group consisting of a reception antenna and a reception inductor, which is different than a transmission antenna or a transmission inductor that is used for producing the radio frequency magnetic field, said reception unit receiving the radio frequency magnetic field signal with the unmodulated magnetic field strength and the radio frequency magnetic field with the modulated magnetic field strength and linked to said evaluation unit; a control unit; said evaluation unit having a detection circuit for ascertaining a received magnetic field strength and supplies it to said control unit configured to ascertain a modulation index mmeasured, the modulation index mmeasured being defined as a quotient of a difference between the unmodulated magnetic field strength ameasured and the modulated magnetic field strength bmeasured and a sum of the two magnetic field strengths ameasured, bmeasured (mmeasured=(ameasured−
bmeasured)/(ameasured+bmeasured)), and to compare an ascertained modulation index mmeasured with a prescribed modulation index mprescribed and to actuate said controllable transmission unit to bring the ascertained modulation index mmeasured more into line with the prescribed modulation index mprescribed; andsaid control unit executing the separate customization sequence iteratively which includes the steps of; subjecting an amplitude of a magnetic field to shift keying between the unmodulated magnetic field strength a and the modulated magnetic field strength b, and varying at least one of the modulated magnetic field strength b or the unmodulated magnetic field strength, in each case on a basis of a comparison between the ascertained the ascertained modulation index mprescribed to be brought more into line with the prescribed modulation index mprescribed; wherein said evaluation unit has a measuring circuit for measuring the ameasured represents the radio frequency magnetic field with the unmodulated magnetic field strength and the bmeasured represents the radio frequency magnetic field with the modulated magnetic field strength for calculating the modulation index mmeasured using the detection circuit of the card reader and wherein said measuring circuit determines the values ameasured, bmeasured representing the magnetic field strengths from the received radio frequency magnetic field signal, so that the values represent a magnetic field strength that is averaged over time. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification