The difference between active and passive fingerprint identification?


Active principle is mainly through the addition of the drive signal (such as Ring) to the finger to enhance the finger surface to enhance the charge,So that the bottom of the induction array to receive the electric field signal and the signal amplification, according to the fingerprint irregularities inconsistent under the chip induced electric field is inconsistent to reproduce the fingerprint.


Passive work principle is not the same,It is the use of fingers on the chip surface,Fingerprint of the peak trough on the chip internal capacitance of the upper and lower electrode charge distribution ratio of the impact of the degree of fingerprint to reproduce the fingerprint,No need to increase the driver source,Chip structure is very simple,Because no additional drive signal,So the module does not need external Ring,The module structure is also very simple.


Passive less active than the active noise treatment, the module is more light and lower power consumption.

In principle,Automatic program must be loaded onto the finger driving source,This is also the early time Authentec, FPC, IDEX and other active chip program must have the reasons for the Ring,Although behind the FPC, the top chip factory provides no Ring program,But must be dedicated to a driver chip (such as FPC2050, GF118, etc.)Essentially it did not escape the external characteristics of the drive signal,But the drive signal buried in the chip only inside;Because to specifically drive the chip,This not only makes the cost of the entire module higher,The structure will be more complex.Industry rumored passive program because there is no additional drive signal to enhance,Drive capability is weak,Can not do high light coating or cover program,For this argument may be just opponents of the rhetoric.


Passive signal is indeed no active strong,But do not ignore the impact of noise,Passive because there is no drive source inside,So the noise will be very little,The environment is very clean;For the active drive source is both enhanced signal,But at the same time will produce a very large noise;For the effect of the final signal superposition of the passive can match the thickness of the medium is not necessarily less than the active thin.


Another passive program does not have an additional drive signal,So the power consumption will be smaller than the active.

To sum up,Passive capacitive principle and program than the active program has the above advantages:1, signal acquisition more direct and closer to the principle of the use of the scene;2, the module structure is more simple;3, noise is easier to handle;4, the module is more thin;5, lower power consumption.