Classifications

• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
  • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
  • G06K7/10—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
  • G06K7/10544—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation by scanning of the records by radiation in the optical part of the electromagnetic spectrum
  • G06K7/10821—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation by scanning of the records by radiation in the optical part of the electromagnetic spectrum further details of bar or optical code scanning devices
  • G06K7/1097—Optical sensing of electronic memory record carriers, such as interrogation of RFIDs with an additional optical interface

Definitions

• the present invention is an improvement to these various patents. It relates to a system comprising at least one light energy source comprising at least means for focusing this energy source, and a device for generating optical signals intended for an electro-optical label comprising at least one circuit for detection of these signals and means for ensuring communication between the label and the light energy source, characterized in that the device for generating the optical signals is arranged so as to deliver light signals of very short duration and very high intensity, the label detection circuit comprising at least one level discriminator arranged so as to separate the electrical pulses generated by said light signals from high intensity of those generated by the current intensity signals.
• Figure 1 shows by way of example a light source according to the invention with its focusing means.
• FIG. 2 shows by way of example a part of the internal configuration of the electro-optical label with the means for discriminating the input signals.
• FIG. 3 shows by way of example a part of the internal configuration of the device for generating the optical signals.
• FIG. 4 represents an example of configuration of these optical signals.
• Figure 1 a light source according to the invention comprising three possibilities for generating light.
• filament bulb 1 for example of the halogen type.
• this type of bulb has a good performance in the visible spectrum. It can therefore be used to transmit all or part of the light energy it needs to the label.
• this bulb creates a visible light ray which, properly focused, can be used to aim the label.
• this bulb cannot be used to generate coded optical signals due to the time constant of the filament.
• This diode cannot generate sufficient power to supply the label at a certain distance, on the other hand it can generate fast coded signals which can be easily picked up by the label. This diode could also be used to target the label as long as it works in the visible spectrum.
• These means may comprise only a simple reflector, for example of parabolic shape 4, or more sophisticated optical means comprising for example a set of lenses 5.
• the latter can be arranged so as to form a zoom 6 enabling the radius to be adjusted. bright depending on the distance.
• FIG. 2 shows by way of example a part of the internal configuration of the electro-optical label with the means for discriminating the input signals.
• the five photovoltaic cells 10 necessary to transform the luroineux ray into electrical energy. These 5 cells make it possible to obtain the working voltage of 1.5 to 2.0 volts necessary to supply a low voltage CMOS circuit. If a higher voltage is necessary, for example to write in the memory, this will preferably be obtained by using a voltage booster rather than multiplying the number of cells.
• these cells With a lighting of the order of 2000 to 3000 lux which can be obtained with a halogen bulb from 10 to 50 watts depending on the distance, these cells typically deliver 2.0 volts (0.4 volts per cell) for a current of a few hundred microamps. There is thus sufficient power to operate the system.
• the cells 10 are connected to the emitter of a transistor 11 whose base is connected to a capacitor 12 and the collector to the emitter of a second transistor 13.
• the collector of this transistor 13 is connected to Vss by the resistor 14 and at the entrance to an amph 15.
• the base of the transistor 13 is reed to Vss by a zener diode 36 polarized by the resistor 37.
• this circuit can be explained as follows. When the voltage across the cells 10 is low, the voltage across the zener diode 36 is insufficient for it to be conductive. There is therefore no current flowing in the base of the transistor 13. The latter is non-conductive and no current can pass through the collector of the transistor 11.
• This capacity 12 acts as a buffer capacity and accumulates sufficient energy to deliver current spikes for short periods of time, for example during operations of writing to memory, or when sending light signals in return by means of the LED, which represents peaks of the order of 10 mA for a few microseconds.
• CMOS circuit If the lighting is sufficient, the power generated by the cells becomes greater than that necessary for the proper functioning of the CMOS circuit and the voltage increases.
• the threshold voltage of the zener diode 36 When the threshold voltage of the zener diode 36 is reached, a current is established in this diode through the base of the transistor 13, and thereby between the emitter and the collector towards the resistor 14. Thus, taking into account the gain of the transistor 13 , almost all of the excess current is deflected on the resistor 14 and a voltage appears at the terminals of the latter. This voltage is applied to the input of amph 15 which functions like a level detector. It is known that such simple CMOS amphs have a threshold equal to approximately half of the supply voltage.
• This type of bulb is capable of generating light rays of several hundreds of thousands of lux for a time of the order of a millisecond. This ray is therefore capable of generating at the terminals of the cells 10 a peak current much greater than the average current obtained with the bulb halogen, or in natural lighting, even exceptional. If with 3'000 lux we generate for example a current of 200 microA, this current will pass to 2 mA for 30O00 lux, corresponding lighting I don't already have good sunshine. For a flash delivering 150O00 lux, this current goes to 10 mA.
• the output of amph 15 is connected to the reset input of a flip-flop 16 whose Q output goes to the reset input of a sequence generator 17 such as that described in patent application 03 759/94 -1, and at a first input of an OR gate 18 whose output is rehired at the reset input of a counter 19.
• a pulse appears at the output of the amph 15, the output Q of the " flip- flop 16 goes to 0.
• the counter 19 starts to count, and the sequence generator 17 becomes operational and generates a first batch of reference optical signals via an amplifier 20 and an LED 21. These optical signals reference allow the device to generate the optical signals to the label to synchronize on it.
• the sequence generator 17 delivers a signal corresponding to said window on the control input of an analog switch 22 which rehe cells 10 at the input of an analog amph during the duration of the window.
• This amph is formed by a transistor 23 whose collector is connected to Vdd by the resistor 24 and the emitter at Vss by the resistor 25 connected in parallel with the capacitor 26.
• This emitter is also connected by the resistor 28 at the base of a transistor 27 reliably at Vss by the capacitor 29.
• the emitter of the transistor 27 is rehé at Vss by the resistor 30, while its collector goes on the base of the transistor 23 and on the output of the analog switch 22.
• the analog amph is arranged so as to remove the DC component due either to the halogen bulb, or to ambient light, so as to extract the coded optical signals. The operation is explained as follows:
• the cells 10 generate a voltage of the order of 2.0 volts for a current of a few hundred microamps.
• this voltage is applied to the base of the transistor 23.
• the latter becomes conductive, the capacity 26 this load, as well as the capacity 29 through the resistor 28.
• the voltage on the basis of the transistor 27 becomes sufficient, the latter becomes conductive and derives the current from cells 10. If the resistance 30 is low, the voltage across these cells is thus regulated to approximately the sum of the base-emitter diode thresholds of the transistors 23 and 27. Due to the gain of these transistors, the almost totality of the current coming from the cells 10 is derived in the transistor 27.
• the latter therefore delivers a current equal to that delivered by the cells and functions as a current generator.
• this current generator cannot immediately adapt to sudden variations in current in the cells 10.
• the instantaneous increase in current thus obtained cannot not be absorbed by the transistor 27.
• the totality of this increase in current will therefore pass through the base of the transistor 23 and generate a pulse on the resistor 24.
• This pulse applied by a capacitor 31 at the input of an amplifier 32 is further amplified by the latter.
• the output of this amph 32 is connected to an input of a decoder 33 which delivers to the second input of the OR gate 18 a signal when the train of pulses received at the terminals of the cells 10, appearing amplified at the output of the amp '32, is in accordance with a predetermined sequence.
• FIG. 2 shows by way of example a part of the internal configuration of the device for generating the sequences of optical signals incorporated in the light energy source.
• This device comprises a photo-diode 40 making it possible to receive the optical signals coming from the label.
• This photo-diode 40 is connected to an amplifier-decoder 41 itself connected to a sequence generator 42.
• This configuration of circuits makes it possible to amplify the signals received at the terminals of the photo-diode 40 and to analyze their distribution in time according to a procedure similar to that described in patent application 03 759 / 94-1.
• the sequence generators of the tag and of this device must work synchronously. This is easily re-usable if the two generators have a precise time base.
• Synchronization can be obtained by a simple periodic reset to 0 of the time base of the present device in response to a particular configuration of the optical signals coming from the label, decoded by the ampli-decoder 41.
• the amplifier-decoder 41 uses a quartz 43, just like the time base of the label sequence generator.
• the fact that it is the generator of the present device which synchronizes with that of the label, and not vice versa, has an essential advantage. In fact, if two labels were in close proximity to one another and were awakened simultaneously by the flash, it is unlikely that they would simultaneously transmit their reference optical signals.
• the generator of the present device can therefore be synchronized either on one or on the other, according to criteria to be defined. Thus only the label which receives synchronous signals will continue to transmit, while the other will be automatically deactivated as we have seen in the previous figure.
• the sequence generator 42 delivers the signals controlling the ignition of the various light sources, namely the halogen bulb 44, the LED diode 45 and the flash bulb 46. These control signals come in two configurations which we will describe in a way detailed below, this according to the position of the switch 46, corresponding to the switching means 7 of FIG. 1.
• Synchronization of generator 42, establishment and maintenance of communication by means of LED 45 The halogen lamp 44 and LED 45 can be supplied directly at low voltage by generator 42.
• the procedure is a little more complex, whatever perfectly known.
• a capacitor 47 is charged at high voltage, for example 250 V direct, by means of a system represented in a simplified manner by the diode 48 reheated to said capacitor by the current limiting resistor 49. If this system is rehe charging to the sector, the capacity 47 will charge at the peak sector voltage, ie more than 250 V. This voltage is however insufficient to initiate the discharge. This is caused by an overvoltage of several volt rnilhers generated on a special electrode 50 by means of a priming coil 51 controlled by the sequence generator 42.
• the gas of the bulb becomes ionized and becomes perfectly conductive. If the capacity 47 was connected directly to the terminals of the bulb, the latter would then be completely drained, and it is the value of this capacity which would determine the duration of the flash as occurs in simple commercial photographic flashes. When the capacity is completely emptied and the current has passed below a critical threshold, the gas deionizes and becomes non-conductive again. The capacity can then recharge. As soon as it has reached its setpoint voltage, a new flash can be triggered by generating a new overvoltage at the terminals of the coil 51. In the case of FIG. 3, a transistor 52 has been incorporated in series with the flash bulb 50. If this transistor remains permanently conductive, we will have the scenario described above. On the other hand, by making this transistor non-conductive, it is possible to cut the current in the flash bulb so as to control with more precision the duration of the light signal, see to modulate this signal as we can see in the figure next.
• FIG. 4 represents a particular configuration of the optical signals emitted by the device of FIG. 3.
• Configuration 1 above works very well up to a certain distance, i.e. around 50 to 70 cm for a halogen bulb of a few Watts. But we know that the energy required increases with the square of the distance. Thus, to work at a greater distance, it would require a bulb added to certainly several tens of watts. However, this bulb, we already have it available in the form of the flash lamp.
• the flash may completely saturate the cells, and secondly to save energy, especially when you want a portable and autonomous device.
• the switch 46 makes it possible to initiate a second configuration.
• Flash lamp 46 on to wake up the label Synchronization of the generator 42, establishment and maintenance of the communication by means of the LED 45 (ev. Of the flash lamp 46) Sending of flashes at the beginning of each train of pulses as additional supply of energy to the label.

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• Physics & Mathematics (AREA)
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Applications Claiming Priority (3)

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• 1996
  • 1996-08-07 AU AU65115/96A patent/AU6511596A/en not_active Abandoned
  • 1996-08-07 MX MX9800579A patent/MX9800579A/es unknown
  • 1996-08-07 PL PL96324697A patent/PL324697A1/xx unknown
  • 1996-08-07 EP EP96924730A patent/EP0845128A1/de not_active Withdrawn
  • 1996-08-07 SK SK159-98A patent/SK15998A3/sk unknown
  • 1996-08-07 WO PCT/CH1996/000276 patent/WO1997007479A1/fr not_active Application Discontinuation
  • 1996-08-07 CN CN96196275A patent/CN1193396A/zh active Pending
  • 1996-08-07 JP JP9508785A patent/JPH11510926A/ja active Pending
  • 1996-08-07 HU HU9900249A patent/HUP9900249A2/hu unknown
  • 1996-08-07 CA CA002228754A patent/CA2228754A1/en not_active Abandoned

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