Person identification apparatus

An apparatus and a method for identifying a person by making use of his fingerprint. The uneven fingerprint surface of a finger is scanned by a laser beam through a transparent plate. The distance between positions of the surface of the transparent plate serving as a reference surface of reflection and of the uneven surface of the fingerprint is detected as a deviation value due to the scanning. Pattern information obtained from the deviation value is indicative of undulation of the uneven surface of the fingerprint. The pattern information is collated with registered fingerprint data so as to determine whether or not the person whose fingerprint has been detected is registered or not.

BACKGROUND OF THE INVENTION 
This invention relates to a person identification apparatus which is used 
for permitting only specified persons to enter a specific room or for 
preventing a car from burglary or the like. 
Conventional person identification apparatus are generally divided into two 
types one of which uses the physical information such as fingerprint, 
retina in the dorsal aspect of eyes, signature, voice and the like, and 
the other type uses cards such as magnetic cards, IC cards, radio 
responsive cards and the like. 
In the apparatus using the physical information, the fingerprint, retina or 
the like is read as a pictorial image, and subjected to image processing, 
and collated with the personal pattern registered beforehand. 
Particularly, in case of the fingerprint identification, light is applied 
to a fingerprint so as to form shade by the reflected light, which shade 
is to be used as an input image. The input image is subjected to the 
preparation in which the fingerprint is changed into a black and white 
image of about 128-256 gradations with a resolution of about 512.times.512 
picture elements, and after the smoothing and the image enhancement are 
effected to correct unclear portions, the binarization is carried out. 
Thereafter, minutiae are used as the characteristics of the fingerprint. 
In the apparatus using the voice, since not only the personal information 
but also the contents of the talk and the feelings are included as the 
information, it is very difficult to extract only the personal 
information. 
In such conventional person identification apparatus, the physical 
information such as the fingerprint obtained as the two-dimensional image 
information is a random pattern so that a very complicated image 
processing technique is required. 
Further, although the identification apparatus using the cards is the 
generally used person identification apparatus at present, it is 
disadvantageous in that the person must carry the card and there is a 
possibility that the card is abused when lost. 
SUMMARY OF THE INVENTION 
The present invention was originated in view of the above-described 
technical background. 
An object of the present invention is to solve at least a part of the 
problems encountered in the prior arts. 
Another object of the invention is to provide a person identification 
apparatus and a method therefor which have no need of using any pattern 
recognition techniques based on a complicated image processing and which 
are not adversely affected by the reflection factor of finger which is 
different individually. 
To this end, there are provided the following apparatus and method. 
1. A person identification apparatus comprising: a laser beam source; an 
optical scanning system for scanning a fingerprint surface of a finger by 
applying a laser beam, which system serves to make the laser beam emitted 
from the laser beam source incident obliquely on the finger print surface; 
an unevenness detecting element serving to receive laser beam ray 
reflected from an uneven surface of the fingerprint so as to detect 
variation amount of relative positions of the uneven surface with respect 
to a reference surface; and collating means for collating output from the 
unevenness detecting element with registered personal data. 
2. A person identification method comprising the steps of: scanning a 
fingerprint surface of a finger through a transparent plate by means of a 
laser beam; detecting the distance between the surface of the transparent 
plate serving as a reference surface of reflection and each position of an 
uneven surface of the fingerprint as a deviation value by the scanning; 
obtaining a pattern information from the deviation value as being in the 
form of undulation of the uneven surface of the fingerprint; and collating 
the pattern information with the registered fingerprint data so as to 
identify the person having the finger concerned. 
According to the present invention, the fingerprint is scanned by the laser 
beam so that the deviation between the position on which the light is 
reflected in accordance with the unevenness of the fingerprint and the 
position on which the light is reflected from the reference surface of 
reflection, that is, the path obtained as a result of the scanning on the 
fingerprint, is changed into the pattern information which is to be used 
for collation with the registered data, and therefore, it is possible to 
obtain stable information without requiring the pattern recognition 
technique based on complicated two-dimensional image processing and 
without being affected by the variation of the intensity of the reflected 
ray attributable to the discrepancies in the reflection factors of the 
fingers of the individuals.

DETAILED DESCRIPTION OF THE INVENTION 
As shown in FIG. 1, a person identification apparatus is provided with an 
irradiation optical system consisting of a semiconductor laser 11, a slit 
12 disposed in front of the semiconductor laser 11, a collimating lens 13, 
a movable reflector 14 serving to make the laser beam scan on the 
fingerprint of a finger 18, and a condensing lens 15, and with a light 
receiving optical system consisting of a condensing lens 16 serving to 
gather the light reflected from the fingerprint on a two-dimensional 
position detecting element (or an unevenness detecting element) 17. 
Further, the apparatus is provided with a photosensor consisting of a light 
emitter 19 and a light receiver 20 for detecting the existence of the 
finger 18. 
As shown in FIG. 2, the person identification apparatus comprises a 
semiconductor laser driving circuit 22 which starts to operate according 
to an output from a photosensor 21 serving to confirm that the finger 18 
is set in the fixed position so as to drive the semiconductor laser 11, an 
optical system position control unit 24 for controlling the positions of 
the movable reflector 14 and the condensing lens 15, a position detecting 
element driving circuit 26 for driving the position detecting element 17 
of the two-dimensional position detecting element, and a person collating 
unit 28 for collating a picture signal sent out from the position 
detecting element 17 with the personal data. 
Next, operation of the embodiment having the above-described arrangements 
will be described. 
As shown in FIG. 1, as the finger 18 is put on, the light incident from the 
light emitter 19 to the light receiver 20 of the photosensor 21 is cut off 
so that an output is generated. This output is introduced to the 
semiconductor laser driving circuit 22, the optical system position 
control circuit 24 and the position detecting element driving circuit 26. 
An output of the semiconductor laser driving circuit 22 causes the 
semiconductor laser 11 to emit the light beam and an output of the 
position detecting element driving circuit 26 causes the position 
detecting element 17 to start operating. 
Then, while keeping the positions of the movable reflector 14 and the 
condensing lens 15 under the control of the optical system position 
control circuit 24, the laser beam is used to scan on the fingerprint as 
shown in FIG. 3. Namely, by rotating the reflector 14 about y- and z-axes 
respectively, the scanning on the fingerprint 34 is performed 
two-dimensionally in the directions of y- and z-axes, as shown in FIG. 5. 
In case of scanning in the direction of the y-axis, the focal point 
changes, the position of the condensing lens 15 is moved in accordance 
with the angle of deviation .theta. of the reflector 14 within the range 
of .+-.f, as shown in FIG. 4. This makes it possible to perform the 
scanning in focus at any position 
As shown in FIG. 6, when the scanning is performed on the fingerprint 34 
with a laser beam 30, there is generated a reflected ray 32 which 
corresponds to the inherent unevenness of each fingerprint 34. The 
reflected ray 32 is made to be incident on the position detecting element 
17 through the lens 16. 
In this case, since a reflected ray 31 of the laser beam 30 which is 
reflected from a reference surface of reflection of a transparent plate 
(such as a glass plate) 33 is discrepant from the reflected ray 32 which 
is reflected from the uneven surface of the fingerprint 34 on the light 
receiving surface of the position detecting element 17 by a discrepancy of 
.DELTA.d, pattern information is formed on the basis of the discrepancy 
.DELTA.d thus detected, which pattern information is used as collation 
data. 
As shown in a flow chart of FIG. 8, the data obtained by the position 
detecting element 17 is converted into digital data by an A/D converter 
35. Then, a deviation .DELTA.d between the digital data thus converted and 
the reference surface of reflection 33 registered previously is obtained 
by calculation in a .DELTA.d calculating means 36. 
Output of the .DELTA.d calculating means 36, which includes noise component 
as shown in FIG. 7A, is made to be subjected to the average processing in 
a moving average processing means 37 so that it is possible to obtain the 
data shown in FIG. 7B from which the noise component is eliminated. 
A variance .sigma..sup.2 for this data is obtained in a variance 
.sigma..sup.2 calculating means 38. The variance .sigma..sup.2 thus 
obtained is used for the retrieval of registered data 40-42 in a collating 
means 39. Referring to FIG. 8, the registered data 40, 41 and 42 are the 
fingerprint information of three persons a, b and c. Results of the 
scanning about scanning positions Z.sub.1, Z.sub.2 and Z.sub.n are 
previously registered in the memory as the registered data 40, 41 and 42, 
respectively, that is, as the variance .sigma..sup.2 (.sigma..sub.a.sup.2, 
.sigma..sub.b.sup.2, .sigma..sub.c.sup.2) representing the fingerprint 
information of each person. For example, when the finger shown in FIG. 5 
is scanned about the scanning position (or line) Z.sub.1, the result of 
the scanning is calculated in the calculating means 38 so as to obtain a 
variance .sigma..sup.2 which is collated with the registered data 40 of 
three persons a, b and c. 
In a collating means 39, the variance .sigma..sup.2 is collated with the 
registered data 40-42 for every scanning position. 
A signal indicative of the scanning position is sent out from the optical 
system position control unit 24 to the collating means. 
After the variance is confirmed to be coincident with the registered data 
40-42 in a branch point 43 where a judgement is effected on the 
coincidence, it is checked in an n-line scanning judging means 44 whether 
or not the scanning was performed about all the predetermined scanning 
positions Z.sub.1 . . . Z.sub.n. If it is not confirmed to be coincident, 
operation is brought to an end. The n-line scanning judging means 44 
serves to confirm how many lines were scanned. If the number of 
repetitions of the scanning does not reach a predetermined number (n), the 
program is returned to operate the position detecting element 17 so that 
the same operation is repeated. 
Thus, the scanning is performed on n lines as shown in FIG. 5 and the 
pattern collation is performed for each scanning position, and thereby it 
is possible to improve the accuracy of person identification. 
When the scanning has been performed by the predetermined number of 
repetitions, a collation confirming unit 45 produces a signal so that a 
control signal is transferred to various kinds of application device such 
as an electronic lock for making them operate so as to unlock the 
electronic lock, thus completing the operation. 
As will be apparent from the above, according to the present invention, it 
is possible to perform the person identification by the information of a 
locus pattern by the reflected ray without requiring any complicated image 
processing. Since this pattern information uses only the position 
information of the reflected ray, it is not adversely affected by the 
variation of the intensity of the reflected ray attributable to a 
variation in the reflection factors of the fingers of the individuals, 
with the result that it is possible to obtain stable information. 
Further, after the noise is eliminated from the obtained data in the moving 
average processing means 37, the variance .sigma..sup.2 is calculated in 
the calculating means 38. By performing such data processing prior to the 
collation, it is possible to reduce further the time required for the 
collation of the measured data with the registered data.