Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – With specific source of supply or bias voltage
Patent
1996-08-16
1998-09-01
Callahan, Timothy P.
Miscellaneous active electrical nonlinear devices, circuits, and
Specific identifiable device, circuit, or system
With specific source of supply or bias voltage
327538, 327540, G05F 110
Patent
active
058015752
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to the control of the operation of the electronic means of a portable object equipped with an antenna enabling these electronic means to be supplied electrically.
BACKGROUND
The invention applies advantageously but non-limitingly to the supervision of access to a building, for example. During such supervision, the bearer of the portable object, such as a card, presents the latter in proximity to a terminal cooperating electromagnetically with the antenna of the card. The electromagnetic energy received by the antenna of the card makes it possible to energize the chip installed in its surface. When the supply voltage delivered is sufficient, the processing means of the card are between the terminal and the card.
However, during the activation of the electronic processing means, the latter suddenly absorb part of the energy available, bringing about an abrupt drop in the supply voltage available. This may result in a shutdown of the operation of these electronic means if the voltage available drops below a floor threshold. After the shut down of the operation of the electronic means, the voltage rises again to allow reactivation of the electronic means, so leading to a repetition of the phenomenon just described.
These successive fits and starts are prejudicial to the proper operation of the electronics of the card.
SUMMARY
The invention aims to afford a solution to this problem.
Its object is to allow crisp starting of the electronic processing means of the portable object, avoiding successive shutdowns and restarts following a sudden power demand.
The invention therefore proposes a device for controlling the operation of the electronic processing means of a portable object equipped with an antenna, which comprises, connected to the antenna, a rectifier delivering a primary DC supply voltage at its output terminal, and stabilizing means for generating a stabilized DC voltage from the said primary voltage. First means calculate a first prespecified voltage threshold corresponding to a prespecified level of the stabilized DC supply voltage. The device also comprises comparison means, the output terminal of which is connected to the processing means, a first input of which is connected to the output of the first calculating means, and a second input of which is connected to the output terminal of the rectifier. The comparison means are intended overall to compare the primary voltage with the first threshold. A load with chosen impedance with is also provided, connected between the said output terminal of the rectifier and earth by way of a controllable switching means whose control input is joined to the output terminal of the comparison means.
The prespecified level of the (virtually constant) stabilized voltage corresponds to a sufficient level of supply to the electronic means arranged down-stream of the device allowing them to operate correctly. Moreover, by reason especially of the absorption of energy inherent to the stabilizing means, the value of the stabilized voltage is below that of the primary voltage. Additionally, the first voltage threshold (for example 5.5 volts) is above this level of the stabilized voltage (for example 4.2 volts).
As far as the impedance of the said load is concerned, it is chosen as a function of the electrical characteristics of the electronic processing means arranged downstream of the device according to the invention. More precisely, the impedance of this load is chosen as a function of the quantity of energy absorbed by the electronic processing means during their activation (power demand).
In other words, a load with chosen impedance is used, during the rise in the supply voltage and when the electronic processing means are not as yet activated, to simulate, as regards the energy absorbed, these electronic processing means. Thus, when the supply voltage reaches the said first voltage threshold, the load is disconnected and the electronic processing means are activated, which then produces virtually no voltage drop or power d
REFERENCES:
patent: 4594517 (1986-06-01), Cohen et al.
patent: 5276646 (1994-01-01), Kim et al.
patent: 5498995 (1996-03-01), Szepesi et al.
Callahan Timothy P.
France Telecom
Shin Eunja
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