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On radio frequency identification system and an overview of non-contact IC card


The same, the energy of the charge transfer phase, the chip is in standby mode or hibernate mode, virtually no power consumption. Should seek to charge the capacitor in the charging mode is completely put the beginning of electricity, while the charging circuit of the ohmic resistance is extremely small, then the charge current is large, but the pressure drop across the capacitor is close to 0, with the capacitor charging people gradually charge, the charge current in accordance with the decreasing exponential function e. When the capacitor voltage is equal to the transponder coil voltage trends, the charging current also tends to 0. This work shows that the chip timing of energy supply has the following advantages can answer all of the voltage coil used for the chip work. Therefore, the operating voltage than the full duplex / half-duplex system, the high voltage is almost doubled: * for the chips used in the capacity of energy from charging the capacitor charging time and the size and length of decision. Because of the flexibility to choose the parameters of the two, end leaves the system designer to optimize the system enough room to work. 2, should Rong Tian reader device to transmit music data block diagram of the transponder shown in Figure 10. In the timing system, the transponder reader to read the information work cycle can be divided into three stages, shown in Figure 11. - Charging period transponder reader to transfer energy and information stages: * read out the phase of the transponder to send the information to the reader the order of ≯ i,[link widoczny dla zalogowanych], i: Section: * Discharge stage: This is the transponder to prepare for the next work cycle stage. We can see from the above-mentioned process,[link widoczny dla zalogowanych], the charge cycle detection circuit monitors the voltage of the transponder coil magnetic field to identify the cut off time reader. End of the period in charge, start transponder chip-chip oscillator, the vibration off the device using transponder coil to determine its oscillation frequency. It generates a weak alternating magnetic field reader antenna coil can be received, because at this time is not itself on the reader coil oscillation signal, and full duplex / half-duplex system, in comparison,[link widoczny dla zalogowanych], has about 20dB of signal to interference ratio improvement , can effectively improve the role distance. For modulated HF signal, with the serial shift of data to switch off the circuit and mode of a capacitor in parallel to achieve 2FSK modulation. After the data transfer into the discharge stage, the charging capacitor is fully discharged, the charge to ensure that the next stage, the power is completely reset. 3 SAW Surface Acoustic Wave Components should Rong (SuffaceACOUsticWaveDe-vices-_sAwJ is a piezoelectric effect and the sound waves spread along the surface at low speed based. SAW response Used to work at microwave frequencies,[link widoczny dla zalogowanych], usually in the 245GHz to IsM (Industrial Scientific Medical) band. Some ionic crystals under the action of external mechanical deformation in its side surface on both sides of the induced voltage is called the piezoelectric effect. This phenomenon originated in the polarization properties of crystals, crystal princess on point positive and negative ions in the external shear displacement under the action of force, so that the original neutral crystals slightly positive and negative power center separate from the polarization, when the crystal structure of the symmetry center no longer has to equal the symbol appears on both sides opposite charge and voltage. piezoelectric effect is reversible, that is the applied external voltage transistors can cause deformation of the crystal to produce electricity. wave is a pressure wave, high frequency alternating voltage wave can generate a high frequency crystal acoustic; the other hand high-frequency sound waves can also produce high-frequency crystal surfaces at both ends of the voltage wave. In this electro-acoustic sound waves generated by the phenomenon is mainly spread along the surface of the object light, the acoustic wave is the use of a transponder This electro-acoustic effects posed by the transponder. SAW transponder usually has a lithium niobate piezoelectric effect or lithium tantalate as the substrate, the surface coated with aluminum, then lithography method of printing on the substrate planar electrode structure to produce electro-acoustic converter (internal digital converter) and the reflector. The basic structure shown in Figure 12. In the long ends of the piezoelectric substrate produced a finger electrode structure - Internal digital conversion device. ribbon emblem on the bus with the line connecting the dipole antenna. internal digital signal and the converter is the conversion between the surface acoustic wave used. piezoelectric crystal is encapsulated in the metal shell. to the dipole antenna Reader inquiry sent to the telecommunications numbers,[link widoczny dla zalogowanych], the applied electrical pulses on the bus between the finger electrode piezoelectric effect, deformation of the substrate surface to form a wave propagation in both directions. on the common substrate materials that the sound wave propagation speed is about 3000 ~ 4000m/so wave propagation in the left side to the edge of Scientology film, after special treatment of the film side is absorbed, the energy consumption of this part. to the right side of the surface wave propagation, then As in the dissemination process, continue to face reflector, a portion of the wave reflected back to digital converter. Kim, Department of Electronics and Information bamboo mat contracting ... 152 29'j scape key.
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