Patent Application
20120228478
The present invention concerns the field of portable electronic devices, in particular electronic cards, provided with a switch that can be actuated by a user to activate an electronic unit and/or to supply a command or instruction thereto. It will be noted that, within the scope of the present invention, the function of the switch is in no way limiting, and may relate to the activation of an electronic unit or only one part thereof (in particular for powering or initialising said unit or establishing a connection with another unit of the portable electronic device), or to the launching of an application or a step in an application, or to a command or instruction, in particular for selecting an element in a sequentially displayed list or for giving a transaction confirmation signal, etc.
Portable electronic devices provided with switches having various configurations are known. In general, these switches are formed by a pressure device on which the user has to exert a certain level of pressure to activate the switch, for example a keyboard key or a push-button. It is also known that a switch can be achieved without any exertion of pressure, for example in the form of a capacitive sensor sensitive to the presence of a finger or a light sensitive optical sensor.
In particular in the case of electronic cards, the use of a push-button incorporated into the card, which has an elastically deformable area for activating the switch, has certain drawbacks. First of all, the arrangement of these push buttons makes the cards more complex to manufacture. Next, the presence of an area that can be elastically deformed by a user's finger raises a problem if it is sought to obtain a flat card with a surface having no hollows or raised portions. Moreover, repeated activation of the switch tends to leave a slight depression in the area of the push button. Finally, a major problem arises from the fact that an electronic card, particularly a bank card, is generally carried on the person, so that pressure may be inadvertently and randomly exerted on the push button and may thereby inadvertently activate the switch. This may cause a problem of electric power consumption or disrupt the proper operation of an application of the electronic card.
It is an object of the present invention to provide a portable electronic device provided with a switch that can be activated by a user, which does not have the drawbacks of the aforementioned prior art. In particular, it is an object of the invention to provide an electronic card provided with a switch which can be actuated by a user and does not require any local deformation of the card and which does not react to the application of pressure.
The present invention concerns a portable electronic device including at least one electronic unit and one switch which can be activated by a user and is associated with said electronic unit, particularly for actuating and/or supplying said unit with a command or instruction. This electronic device is characterized in that the switch is formed by two independent photo-detectors which are sufficiently far from each other to enable the user to cover only one of these two photo-detectors with his finger, and in that the switch further includes a logic circuit to which first and second light reception signals are respectively supplied by the two photo-detectors, said logic circuit being arranged to provide a signal indicating actuation of said switch only when said first and said second light reception signals correspond to two different logic states for said logic circuit.
According to a particular feature of the invention, the two photo-detectors are arranged to supply a voltage signal whose value varies according to the quantity of light received.
According to a preferred embodiment, each of the two photo-detectors includes a light sensor and a comparator. The comparator receives at input a reference signal and a measuring signal from the light sensor. It supplies at output a logic signal which is in a first logic state when the value of the measuring signal is higher than that of the reference signal and otherwise is in a second logic state. The comparator output signal defines the first or second light reception signal respectively.
The logic circuit, according to a first embodiment, is formed by an Exclusive OR (XOR) gate, respectively receiving said first and second signals at its two inputs.
The logic circuit according to a second embodiment is formed by an AND gate with a single inverter arranged at one of its two inputs, which respectively receive said first and second signals.
According to a particular embodiment of the invention, the two photo-detectors are respectively arranged in two opposite areas of the electronic card.
The portable electronic device according to the invention therefore allows an optical switch to be used very efficiently owing to the fact that the optical switch is formed of two independent photo-detectors sufficiently far from each other to allow a user to obscure only one of the two photo-detectors with one finger. When the two photo-detectors receive light or when they are in darkness and are receiving little or no light, the optical switch is not actuated and thus remains in an OFF state.
It is clear that with only one photo-detector, it is difficult to provide an optical switch for an electronic card, given that it is difficult for the user to control the reception of light by a single photo-detector. When the user takes his electronic card out of his card holder for example, the single photo-detector then immediately receives light, which actuates the switch before the user has taken any deliberate action. The presence of two photo-detectors at a distance from each other provides an efficient optical switch, which is generally only actuated when the user so wishes, in particular to start a banking application.
Other features and advantages of the present invention will also appear upon reading the following description, made with reference to the annexed drawings, given by way of non-limiting example, in which:
Signal S3 indicating actuation of switch 12 has a high level or logic state “1” when the first signal S1 and second signal S2 respectively correspond to two different logic states for logic circuit 14. Thus, according to the invention, when the two photo-detectors 6 and 8 both receive substantially the same quantity of light or substantially no light, optical switch 12 is not actuated and the signal that it supplies corresponds to a low level or logic state “0” in the preferred variant. This logic state “0” corresponds to an open position of optical switch 12, i.e. to an OFF state. When the user obscures or covers only one of the two photo-detectors while electronic card 2 is in a luminous environment, the XOR gate supplies a signal S3 corresponding to logic state “1”, i.e. to a closed position of the switch corresponding to an ON state. Thus, logic circuit 4 only receives a signal indicting activation of the optical switch when said first and second light reception signals correspond to two different logic states of the XOR logic gate.
When the electronic card is entirely in darkness, particularly inside a wallet or card holder, the optical switch remains continuously deactivated. Likewise, when electronic card 2 is entirely situated in a luminous environment and neither of the two photo-detectors is obscured, the optical switch also remains deactivated. Only an action consisting in obscuring or covering one of the two photo-detectors causes actuation of optical switch 12 and communication of a command or instruction to the electronic system incorporated in card 2.
It will be noted that in the first embodiment of the invention, and in the other embodiments described below, the photo-detectors 6 and 8 are arranged to provide voltage signals whose value varies according to the quantity of light received. Thus, signals S1 and S2 are voltage signals applied to logic circuit 14. Those skilled in the art know how to make these photo-detectors. Signals S1 and S2 may be either analogue signals, or digital signals provided by an analogue-digital converter internal to the photo-detectors.
In the first embodiment, a signal indicating actuation of the optical switch is supplied regardless of whether it is the first photo-detector 6 or second photo-detector 8 which is obscured while the other is receiving light. In the second embodiment, this symmetry does not exist. The only situation which results in actuation of the optical switch is where photo-detector 6 receives light whereas photo-detector 8 does not. The variant shown in
A third embodiment of the invention will be described with reference to
In the variant shown, the delay circuit 32, given by way of non-limiting example, is arranged after logic circuit 14. This delay circuit thus receives a logic signal S3 indicating whether the two photo-detectors 6 and 8 have different logic states. Signal S3 is, on the one hand, directly supplied to an input of an AND logic gate 38, and on the other hand, to an N counter, referenced 34. This counter 34 is clocked by a clock signal 36. The counter output signal is supplied to the second input of logic gate 38. Counter 34 is arranged so that it remains at the reset value as long as the signal S3 received at the input thereof corresponds to a low level, i.e. to a logic state “0”. As soon as logic signal S3 changes to a high level, i.e. to a logic state “1”, the counter is incremented to value N. Preferably, it remains at this value N as long as input signal S3 has a high level. Output signal S6 from counter 34 corresponds to a logic state “0” as long as the counter has a lower value than N. Only when the counter has value N does signal S6 correspond to a logic state “1”.
The AND logic gate supplies a logic signal S5 indicating actuation of the optical switch 30 to electronic unit 4 as soon as signal S6 changes to logic state “1”. Thus this logic signal S5 only has a logic state “1” when counter 34 reaches the value corresponding to N. In order to be incremented from zero value to value N, counter 34 operates for a certain time period T determined by the clock signal which clocks said counter. Consequently, as long as the two photo-detectors 6 and 8 have not been in a different logic state for at least said determined time period T defining a delay or lag in activation of optical switch 30, the signal S5 supplied to electronic unit 4 corresponds to an OFF control signal, i.e. to a deactivated state for the optical switch. The optical switch is thus only actuated when the two photo-detectors 6 and 8 have respectively supplied first and second signals corresponding to two different logic states for a greater length of time than time period or lag T. If the different logic states last for a shorter period than said time period T, signal S3 supplied by logic circuit 14 again changes to logic state “0”, before counter 34 reaches maximum value N. This causes the counter to be reset before it reaches value N and signal S6 therefore remains in logic state “0”. Signal S6 thus defines an inhibition signal preventing actuation of the optical switch during a determined time lag. The switch is not actuated in an initial period after the start of an external situation which corresponds to a normal actuation situation for the switch, namely differentiated reception of light by the two photo-detectors.
In short, delay circuit 32 is arranged to supply the signal indicating actuation of the optical switch to electronic unit 4 only when the two different logic states of the two logic signals S1 and S2 have simultaneously lasted longer than a reference period. The counter provided in the delay circuit is reset to zero as soon as the first and second light reception signals S1 and S2 correspond to the same logic state. The counter is activated as soon as these first and second signals have a different logic state and supplies an inhibition signal provided that it has not reached a certain given level. It will be noted that the inhibition signal may preserve logic state “1” as long as the counter remains at value N (logic state “1” corresponds here to a non-inhibited state) or it may only supply a pulse of limited duration. Other variants and alternatives may be envisaged by those skilled in the art.
| Number | Date | Country | Kind |
|---|---|---|---|
| PCT/EP2009/062631 | Sep 2009 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2009/066862 | 12/10/2009 | WO | 00 | 6/1/2012 |
