A programmable gun has a body supporting a handle, a trigger and a pin actuatable between a first position providing for a trigger depression to fire a bullet and a second position restraining the trigger depression. A memory stores a print identifying an authorized person's hand when such person inserts a key in the handle and then grips the handle. Hand prints of one (1) or more authorized persons, or several hand prints of one (1) person, may be stored in the memory when such persons move the key, after insertion, to individual positions and then grip the handle. When an authorized person thereafter grips the handle, that person's hand generates a print for comparison with the prints in the memory. A comparison coincidence produces a pin actuation to the first position. A subsequent gun firing is recorded in the memory as to time and as to the authorized person. When a comparison coincidence is established, the ability to fire the gun continues until such authorized person relinquishes the gun. If the authorized person relinquishes the gun before firing, the pin becomes actuated to the second position after a particular time period. If the authorized person again grips the handle during such particular time period, the time period is re-initiated. When an unauthorized person grips the handle, no comparison coincidence occurs and the pin is not actuated to the first position. A print of such unauthorized person's hand and the recording time are recorded in the memory.

This invention relates to a gun programmable to limit the firing of the gun 
only to a limited number of authorized persons. More particularly, the 
invention relates to a gun which compares the hand prints of proposed 
users with the hand prints stored in a memory in the gun of authorized 
persons and which provide for a firing of the gun only in accordance with 
a coincidence in such comparison. 
The use of guns has proliferated in recent years. Every day in the 
newspapers or on television, there is a grisly story of individuals 
running rampant and firing guns indiscriminately into groups of people and 
killing some and injuring others. The situation has deteriorated so 
significantly that youngsters in their teens and even younger now commonly 
kill fellow students at school. Furthermore, large cities, and now even 
small cities, have gangs of youngsters who wage war on one another and 
kill members of rival gangs and even innocent bystanders. 
Many citizens are buying guns to protect themselves. For example, in 1993 
gun sales increased by approximately twenty percent (20%) in California. 
The proliferation of guns increases the potential for their unauthorized 
use. As gun owners, parents are afraid that their children will attempt to 
operate guns on an unauthorized basis. Homeowners are afraid that a 
criminal unlawfully entering into their home will make unauthorized use of 
their gun. This is a common occurrence today as evidenced by many news 
reports. 
In view of the above, there is a growing consensus that steps have to be 
taken in an attempt to reduce and even minimize the killings that are 
occurring through gun shootings. For example, legislation is now pending 
to permit a sale of a firearm to an individual only after a waiting period 
such as fifteen (15) days. The hope is apparently that an investigation 
can be made of the individual during this waiting period to determine if a 
sale is justified. 
Various attempts have been made from a technological standpoint to limit 
the firing of guns only by authorized persons. For example, a gun has been 
suggested or provided which uses a keypad and a decoder system. This gun 
requires a proposed user to enter a code into the decoder system. The gun 
is enabled to be fired only when the number entered into, and the number 
stored in, the decoder system coincide. As will be appreciated, this 
system is disadvantageous because there is a considerable time delay while 
the proposed user is entering the code into the decoder. During this time 
delay, the proposed user may be in considerable danger. 
Another gun has been provided or suggested which also provides an active 
participation by the user before the gun can be fired. This system 
requires the user to wear a special ring which transmits a coded signal to 
the gun. This is illustrated in U.S. Pat. No. 5,016,376. This signal is 
decoded by a safety system in the gun. The gun is operated only when the 
proper signal or series of signals are transmitted to the safety system in 
the gun. The system involves an active participation by the gun user 
because the user has to wear the special ring. The system is also 
disadvantageous because the gun has to have a battery and the battery 
tends to lose its power with time. 
A number of other systems have been proposed in recent years to regulate 
the operation of a weapon such as a gun. All of such systems operate on an 
active basis which requires some participation by the proposed user other 
than merely to operate the gun. These requirements for active 
participation by the proposed user are disadvantageous because they either 
require a delay in time or some other event (such as the wearing of a 
ring) to occur before the gun can be operated. 
Although a considerable amount of attention has been devoted in recent 
years to providing a gun which limits and regulates the use of the gun 
only to selective persons, the problem still exists. No gun has been 
provided or suggested which regulates the use of the gun effectively on a 
passive basis and which can be used instantaneously after an authorized 
user grips the gun. 
This invention provides a gun which effectively limits or regulates the use 
of the gun on a passive basis so that only authorized users can fire the 
gun on an instantaneous basis after such authorized user has gripped the 
gun. The gun of this invention pre-records a print of an authorized user's 
hand in a memory. When the authorized user thereafter grips the gun, the 
print of the authorized user's hands on the gun handle is compared with 
the stored print of the authorized user's hand. A coincidence in such 
comparison allows the gun to be operated instantaneously after the gun has 
been gripped by the authorized user. 
In one embodiment of the invention, a programmable gun has a body 
supporting a handle, a trigger and a pin actuatable between a first 
position providing for a trigger depression to fire a bullet and a second 
position restraining the trigger depression. A memory stores a print 
identifying a hand of an authorized person when such person inserts a key 
in the handle and then grips the handle. Hand prints of several authorized 
persons may be stored in the memory when such persons move the key, after 
insertion, to individual positions and then grip the handle. 
When an authorized person thereafter grips the handle, that person's hand 
generates a print for comparison with the prints in the memory. A 
comparison coincidence produces a pin actuation to the first position. A 
subsequent gun firing is recorded in the memory as to time and as to the 
authorized person. When a comparison coincidence is established, such 
coincidence continues thereafter while such person grips the handle. The 
pin remains actuated in the first position during this time. The 
comparison coincidence continues even after the user fires the gun. 
If the authorized person relinquishes the gun before firing, the release of 
the membrane switch 20 is sensed and, after a particular period, the 
microprocessor causes the pin to be actuated to the second position. If 
the authorized person again grips the handle and depresses the membrane 
switch before the end of such particular time period, coincidence is 
re-established and the time period is reset. When an unauthorized person 
grips the handle, no comparison coincidence occurs and the pin is not 
actuated to the first position. A print of such unauthorized person's hand 
and the recording time are recorded in the memory.

In one embodiment of the invention, a gun generally indicated at 10 is 
provided in FIGS. 1 and 2. The gun 10 includes a body 12, a handle 14 
integral with the body, a nozzle 16 with an opening for providing for the 
passage of bullets and a rotatable cartridge 18 for holding a plurality of 
bullets. The gun 10 as constructed above is known in the art and is 
considered only to be illustrative. It will be appreciated that different 
embodiments of a gun may be used without departing from the scope of the 
invention. 
The gun 10 includes a sensing pad 20 which is disposed on the side of the 
handle 14 to receive a particular portion, such as the palm, of a person's 
hand when such person grips the handle as illustrated schematically in 
FIG. 1. When this occurs, the sensing pad 20 receives a print of a portion 
of the hand of the person gripping the handle 14. The print includes the 
swirls, and the grooves between the swirls, individual to the hand of such 
proposed user. A sensing pad such as the sensing pad 20 is well known in 
the art. For example, a suitable unit is available from Identix, 
Incorporated, of Sunnyvale, Calif. 
A source of energy such as a battery 22 is also disposed in a socket in the 
handle 14. The battery 22 is disposed so that it is easily accessible and 
can be easily replaced when its energy has become depleted. A membrane 
switch 24 is also disposed in the handle 14 at a position where it is 
engaged by the hand of the person gripping the gun. The membrane switch 24 
includes a membrane which is depressed when the user grips the handle of 
the gun. When the membrane in the switch 24 is depressed, it closes the 
switch. A switch such as the membrane switch 24 is known in the art. 
Indicators are also disposed on the handle 14 or the body 12. For example, 
a buzzer 26 is shown in FIG. 1 as being disposed on the handle 14. The 
buzzer emits a distinctive sound when the gun 10 has been gripped by an 
authorized person and is ready to be fired. Illuminating means such as 
light-emitting diodes 28, 30 and 32 are disposed on the body near the 
handle. The diode 28 produces a green light when the gun 10 is ready to be 
fired. The diode 30 produces a red light when an unauthorized person grips 
the gun 10. 
The diode 32 produces a flashing or blinking light when the gun is in a 
problem status other than being gripped by a non-authorized person. For 
example, the light 32 may flash when the gun has no bullet in the chamber. 
This may be accomplished by a sensor subsystem which indicates 
magnetically the presence of a bullet in a chamber. The disposition of the 
buzzer 26 and the diodes 28, 30 and 32 on the gun may be other than as 
shown in FIG. 1 without departing from the scope of the invention. 
Furthermore, the buzzer 26 and the diodes 28, 30 and 32 are illustrative 
only of the types of sensors and indicators that may be used. 
A memory 34 (FIGS. 1, 3, 4 and 8) is disposed in the handle 14, which may 
be hollow, or in the portion of the body to the rear of the cartridge 18. 
The memory 34 may be constructed in a conventional manner. The memory 34 
stores in binary form the characteristics such as the optical 
characteristics and pattern of the swirls and grooves individual to the 
portion of the hand of an authorized user on the sensing pad 20. This 
binary pattern is obtained by scanning the swirls and grooves in a 
conventional manner and by introducing the resultant signals to a finger 
print reader converter 36 (FIGS. 4, 5 and 6) which may be a 
digital-to-analog converter and which may be constructed in a conventional 
manner. The relative sizes of different elements such as the sensing pad 
20 and the memory 34 are shown only schematically in the drawings and may 
not indicate the actual sizes of these elements. 
The memory 34 may have sufficient capacity to store in binary form the hand 
prints of several authorized users. For example, FIG. 2 illustrates a slot 
40 disposed at the bottom flat surface of the handle 14 for receiving a 
key 41. The key 41 and the slot 40 may respectively have corresponding 
male and female patterns in a conventional manner so that only the key 41 
can fit in the slot 40. As shown in FIG. 2, the slot 40 is disposed in a 
key barrel 44 which is rotated by the key 41 to three (3) different 
positions. It will be appreciated that a different number of positions 
than three (3) may be provided without departing from the scope of the 
invention. 
At each position in the key barrel 44, an authorized person may grip the 
handle 14 to have that person's print pattern recorded and stored in a 
different portion of the memory 34. This may be seen from FIG. 4 which 
shows how the signals from the sensing pad 20 are converted to a binary 
form by the converter 36 after passing through an OR network 83 and are 
directed in the binary form through an individual position in a three 
(3)-position switch 38 to an individual portion of the memory 34. The 
conversion of a hand print to a digital form as by the converter 36 and 
the passage of the converted information through a switch such as the 
switch 38 to a memory such as the memory 34 are well known in the art. 
In FIG. 4, the digital signals from the converter 36 shown as being 
introduced to an AND network 77. These signals pass through the AND 
network 77 when the membrane switch 24 is closed. The digital signals 
passing through the AND network 77 activate the memory 34 so that the 
memory records the signals in the portion of the memory indicated by the 
setting of a movable arm 41 of the switch 38. The movable arm 41 may 
constitute the key 40 which engages individual stationary contacts of the 
switch in accordance with its rotational position in the barrel 44. 
A receptacle 79 (FIG. 2) is provided for receiving a print of the 
particular portion of a person's hand from an external source 81 (FIG. 4). 
The hand print from the external source 81 passes through the OR network 
83 to the converter 36. The resultant digital signals then pass through 
the AND network 77 and the switch 38 to the memory 34 when the membrane 
switch 24 is depressed and the key 40 is disposed in the barrel 44. 
After the hand prints of up to three (3) different persons have been 
recorded in digital form in the memory 34 to authorize these people to 
fire the gun 10, one of these authorized people may grip the handle 14. 
The sensing pad 20 then produces signals which are compared in a 
microprocessor 42 (FIG. 3) with the hand prints stored in the memory 34 
for the three (3) authorized persons. This comparison may be on a 
sequential basis for such three (3) individuals as by scanning successive 
portions of the memory 34. This is indicated in FIG. 3 by the introduction 
of the binary information from the memory 34 through a sequentially 
operated switch 43 to the microprocessor 42, the switch being operative 
sequentially operated through the different positions when the membrane 
switch 24 is depressed. The microprocessor 42 also receives the signals 
from the sensing pad 20. The construction and operation of a 
microprocessor such as the microprocessor 42 for providing a comparison 
are well known in the art. It will also be appreciated that the memory 34 
may store the hand prints of more than three (3) authorized persons and 
that the key barrel 44 and the switch 43 may be moved to more than three 
(3) positions. 
The microprocessor 42 senses whether the binary pattern for the hand print 
in the sensing pad 20 matches or coincides with the binary pattern stored 
in the memory 34 for the hand print of any one of the three (3) authorized 
persons. When such a coincidence occurs, the microprocessor 42 produces a 
signal on a line 46 in FIG. 3. This signal is introduced to the "true" 
input terminal of a flip-flop 48 in FIG. 3. The "true" output terminal of 
the flip-flop is connected to an input terminal of an OR network 50. 
The output terminal of the OR network 50 is common with a gate of a 
transistor 52 which may be an n- type of CMOS transistor. The drain of the 
transistor 52 is connected to a reference such as ground. The source of 
the transistor 52 is common with the cathode of a diode 54 having its 
anode connected to a voltage source 56 for providing a positive potential 
and to one terminal of a solenoid 58. The other terminal of the solenoid 
58 is common with the source of the transistor 52. 
A solenoid for use as the solenoid 58 is illustratively manufactured by 
Guardian Electric Manufacturing Co. The solenoid 58 has a magnetizable 
armature 60 which operates as a magnetizable latching mechanism. The 
magnetizable latching mechanism enables a pin 62 (FIG. 1) to be latched in 
an individual one of two (2) separate positions upon each successive 
energizing of the solenoid 58. In a first position, the pin 62 releases a 
trigger 65 so that the trigger can be depressed to fire the gun. In the 
second position of the pin 62, the pin locks the trigger 65 (FIG. 1) 
against being depressed to fire the gun 10. 
The microprocessor 42 (FIG. 3) compares the binary indications of the hand 
print in the sensing pad 20 and the binary indications in successive ones 
of the three (3) hand prints in the memory 34. When a coincidence occurs 
in this comparison, the microprocessor 42 produces a signal which triggers 
the flip-flop 48 to the true state. The resultant high voltage on the gate 
of the semiconductor 52 causes the semiconductor to become conductive and 
the solenoid 58 to become energized. The armature 60 accordingly moves to 
a position in which the pin 62 is latched in its first position. In this 
position, the trigger 65 is released so that it can be depressed to fire 
the gun. The green light 28 becomes illuminated at the same time as the 
release of the trigger 65 to indicate that the gun 10 is ready to be 
fired. The buzzer 26 may also be operated at this time. 
The latching of the pin 62 to the first position as by the operation of the 
flip-flop 48 is advantageous since it minimizes any drainage of electrical 
power in energizing means such as a battery for the electrical circuitry. 
This energizing means may be the battery 22. This results from the fact 
that the flip-flop 48, being bistable, has to be operative only for an 
instant. It will be appreciated that the pin 62 may be operated by 
mechanical means instead of by the solenoid 58 without departing from the 
scope of the invention. A mechanical arrangement may be advantageous 
because it does not require electrical power for its operation. 
The operation of the microprocessor 42 in determining a coincidence between 
the prints in the sensing pad 20 and the memory 34 is approximately only 
ninety six percent (96%) reliable. This reliability may be significantly 
increased by storing the same print in two (2) of the different positions 
in the memory 34. For example, when the same print is stored in two (2) of 
the three (3) positions in the memory 34, the reliability of the 
determinations from the microprocessor 42 increases to a value greater 
than ninety nine percent (99%). When the same print is stored in the three 
(3) positions in the memory 34, the reliability of the determination from 
the microprocessor 42 approaches one hundred percent (100%). 
When a coincidence occurs between the prints in the sensing pad 20 and the 
memory 34, the microprocessor 42 continues to confirm this coincidence. It 
may sometimes happen, however, that the authorized person may lift his 
hand from the handle 14 or otherwise relinquish his grip on the handle. At 
such a time, the microprocessor 42 may produce a signal on a line 64. This 
signal is introduced to timing circuitry such as a counter 66. 
The counter 66 is preset to count a particular period such as approximately 
twenty (20) seconds. If this period passes without a signal on the line 
46, the counter 66 counts down to a value such as zero (0). At this count, 
the counter 66 passes a signal through the OR network 50 to the gate of 
the transistor 52. The resultant current through the transistor 52 
energizes the solenoid 58 and causes the rod 60 to move the pin 62 to the 
second position. In this position, the pin 62 locks the trigger 65 and 
prevents the trigger from being depressed. 
After the authorized user relinquishes the user's grip on the handle 14, 
the authorized user may subsequently grip the handle. When this occurs, a 
signal is again produced on the line 46 to indicate a coincidence between 
the prints in the sensing pad 20 and the memory 34. If this signal occurs 
while the counter 66 is still counting down to a value of zero (0), the 
signal resets the counter so that its value is reset to a full value such 
as twenty (20) seconds. The counter 66 is reset by a signal on a line 68 
which coincides with the line 46. 
The microprocessor 42 then continues to determine coincidence and maintains 
the count in the counter 66 at the full value of twenty (20) seconds upon 
a determination of coincidence. The pin 62 is also maintained in the first 
position so that the gun 10 is prepared to be fired. When the gun 10 is 
fired, the depression of the trigger 65 causes the firing to be recorded 
at a special position in the memory 34. For example, a switch 69 in FIG. 5 
may be closed by the depression of the trigger 65. This may cause a clock 
70 to pass signals representing time through an AND network 74 to a 
recording head 76 in the memory 34. The converter 36 also passes signals 
at this time through an AND network 78 to a recording head 80 to record 
the signals in the sensing pad 20. 
It may sometimes happen that an unauthorized user grips the handle 14. When 
this occurs, the microprocessor 42 will produce a signal on the line 64 
(FIG. 3) to indicate that no coincidence exists between the print in the 
sensing pad 20 and in the memory 34. When a signal is produced on the line 
64, the print in the sensing pad 20 is converted to a digital form by the 
converter 36 in FIG. 4. The digital signals from the converter 36 pass 
through an AND network 82 (FIG. 6) to a recording head 84 which records in 
the memory 34 the binary pattern of the signals in the sensing pad 20, the 
AND network having been activated by the signal on the line 64. 
The binary signals representing the hand print of the unauthorized user are 
recorded in a separate section of the memory 34. The time of such 
recording is also stored in the separate section of the memory 34 by the 
passage through an AND network 86 (FIG. 6) to a recording head 88 of 
binary signals representing the time in the clock 70, the AND network 
having been activated by the signal on the line 64. At the same time, the 
red light 30 is illuminated to indicate that the gun 10 is not ready to be 
fired. 
FIG. 7 is a flow chart illustrating the sequence of operations in the gun 
10. When the handle 14 of the gun 10 is gripped, the switch 24 is closed 
as indicated at 90 in FIG. 7. The coincidence between the prints in the 
sensing pad 20 and the memory 34 is then determined as indicated at 92 in 
FIG. 7. If a coincidence is not initially determined, a signal is provided 
in the microprocessor 42 to obtain another determination. This is 
indicated at 94 in FIG. 7. When this occurs, the print of the unauthorized 
user is recorded in the memory 34 and the position of the pin 62 is 
checked as indicated at 95 in FIG. 7. 
If the pin 62 is latched in the first position as indicated at 97, the pin 
62 is actuated to the second position for preventing the trigger 65 from 
being depressed, as indicated at 93 in FIG. 7. A signal is then provided 
on a line 111 to obtain another determination. 
If the pin 62 is latched in the second position to prevent the trigger 65 
from being depressed, a signal is provided on the line 111 to obtain 
another determination. If a coincidence is determined, the pin 62 is 
retracted to the first position as indicated at 96 in FIG. 7. The buzzer 
26 and/or the light 28 are then energized as indicated at 98 in FIG. 7. 
After the pin 62 has been retracted to the first position, the system 
continues to check the position of the membrane switch 24 as indicated at 
99 in FIG. 7. If the membrane switch 24 has not been released, the pin 62 
continues to be latched and the gun continues to be in a ready mode as 
indicated by the light emitting diode 28. This is indicated by a signal on 
a line 101 in FIG. 7. When the membrane switch 24 is released, the count 
in the counter 66 is initiated as indicated at 100 in FIG. 7. The 
count-down timer 66 checks the position of the membrane switch 24 
continuously. If the membrane switch 24 is re-depressed before the counter 
66 counts down to 0, the system checks the position of a safety switch 
112. 
In one alternative position of the switch 112, a signal is produced on a 
line 114 in FIG. 7, the pin 62 continues to be latched as in 98 and the 
gun continues to be in a ready mode as indicated by the light-emitting 
diode 28. If the membrane switch 24 is not re-depressed before the counter 
counts to 0, a signal is produced on a line 104 in FIG. 7 and the pin 62 
is actuated to the second or retracted position for preventing the trigger 
65 from being depressed. This is indicated at 118 in FIG. 7. In the other 
alternative positive of the safety switch 112, after the membrane switch 
24 has been re-depressed during the count-down time, a signal is produced 
on a line 116 in FIG. 7 and a repeat of the identification routine is 
produced as indicated at 92 in FIG. 7. 
FIG. 8 is a system block diagram representing the electrical and 
electro-mechanical components of the invention. FIG. 8 shows the 
microcomputer 42 which controls the logic functions of the system. The 
microcomputer 42 includes a system ROM (read only memory) and a system RAM 
(random access memory). These memories and the microprocessor 42 execute 
the program logic functions as described in the flow chart shown in FIG. 
9. Also included in the microprocessor 42 are interval timers for keeping 
track of real-time (e.g. time and calendar day) and delay time (e.g. the 
amount of time that the membrane switch 24 has been released). 
Also included in the microcomputer are I/O (input/output) ports 124. By 
including these I/O ports, the microprocessor 42 is able to control the 
operation of, and to communicate with, the different sub-systems shown in 
FIG. 8. One of these subsystems is the data I/O function which may be 
provided by external source 81 (FIG. 4) for communicating data into the 
system from an outside computer such as a computer at a gun service center 
or communicating data from the gun to the outside computer. This provides 
for uploading and downloading (sending and receiving) of information in 
the system. 
Illustrated in FIG. 8 is the memory 34 which stores various fingerprints or 
palmprints and events. These fingerprints correspond to enrolled, and 
therefore allowable, prints of individuals in which the system will go 
into the enabled state by bringing the latching solenoid 58 to the state 
enabling the gun to fire. The memory 34 also stores events such as the 
time and the date that the gun was fired and the identification based on 
the fingerprint of the individual firing the gun. Also stored in the 
memory 34 are fingerprints and the time and the date of the handling and 
attempted operation of the gun by unauthorized individuals who have picked 
up the gun. The sensing pad 20 senses the fingerprints or palmprints. The 
data representing the print is then sent to the microprocessor 42. The 
microprocessor 42 first selects and commands the sensing pad 20 to read 
the print. 
The data I/O ports 124 receive and translate the data signals to the binary 
signals readable by the microprocessor 42. The data sent through the data 
I/O ports 124 to the processor 42 includes information relating to 
enrollment fingerprint data so that fingerprints can be scanned and 
enrolled by an external terminal system that is not part of the unit. This 
is useful to enable controlled enrollment by users operating the terminal 
system. 
The data sent by the microprocessor 42 through the data I/O ports 124 
includes both event data and fingerprint/palmprint data. The event data is 
stored in the memory 34 and comprises events such as when the gun was 
fired and when the gun was picked up by an unenrolled and therefore 
unauthorized individual. The fingerprint palm data represents 
fingerprints/palmprints of both enrolled users and non-enrolled 
unauthorized individuals who picked up the gun. This data is stored in the 
memory 34. 
A switch subsystem 126 provides data to the microprocessor 42 to determine 
if the key 41 has been inserted into the slot 40 and to determine the 
position in which the key is disposed in the barrel 44. The switch system 
126 also provides information to determine whether the sensing pad 20 is 
currently being depressed. This information enables the microprocessor 42 
to determine the proper operational and functional state of the key 41 and 
key barrel 44 in FIG. 2. For example, when the key 41 is in the key barrel 
44 and located at position 2 and the sensing pad 20 is depressed, the 
microprocessor 42 instructs the sensing pad 20 to read the 
fingerprints/palmprints in the sensing pad 20 and to store such finger 
prints/palmprints in the memory 34 for the position 2 and to enroll that 
individual as an authorized user. This is illustrated in the flow chart of 
FIG. 9. 
A display subsystem 128 in FIG. 8 includes, for example, LEDs (such as the 
lights 28, 30 and 32) indicating to the user the specific state of the 
gun. This state can be determined by means of a sensor subsystem 130 which 
can illustratively determine if a bullet is lodged incorrectly in the gun 
chamber. This can cause the gun not to fire or misfire. The sensor 
subsystem 130 can include a magnetic coil which can determine the presence 
of metal such as a bullet that is lodged in an improper position in the 
chamber. 
A driver 134 in FIG. 8 amplifies the logic level signal from the 
microprocessor 42 to a higher voltage and higher current signal capable of 
driving the bi-position latching solenoid 58 to one or the other state. 
The driver 134 can be composed of a transistor array drive device with the 
higher voltage input derived from a power supply 136. The power supply 136 
may be a battery system with voltage regulators and level converters that 
are well-known in the art. 
The bi-position latching solenoid 58 contains a pin that is controllable by 
the position of the solenoid. The pin enables or disables the operation of 
the gun. The latching solenoid 58 can be of the magnetic latching type or 
the mechanical latching type in which two stable positions are achieved. 
This is important because, during operation, if power were required to be 
supplied to the solenoid 58, this requirement could drain the battery and 
prevent the gun from operating during a moment of crisis. By having a 
bi-position latching solenoid 58, a single pulse to the solenoid causes 
the pin to become actuated to a particular position without any additional 
expenditure of power from the power supply 136. 
FIG. 9 is a flowchart illustrating the enrollment procedure for reading and 
storing authorized fingerprints/palmprints. The flowchart operates by 
first reading the switch array positions of the barrel 44 in FIG. 2. The 
positions of the switch array are determined by the key 41 and the 
location (e.g. locations 1, 2 and 3) of the key in the barrel 44. If the 
key 41 is inserted in the barrel 44 and the sensing pad 20 is depressed, 
the system will scan the fingerprint/palmprint data and store that data in 
the particular memory location correlated to the switch position. 
If the key is not inserted in the barrel 44 and the sensing pad 20 is 
depressed and the data signal is not present, the system goes into the 
system operation 142 as illustrated in the left portion of the flowchart 
in FIG. 9. (In FIG. 9, an "N" indicates "No" and a "Y" indicates "Yes".) 
If the key is not inserted in the barrel 44 and the sensing pad 20 is not 
depressed, the system goes into the system operation 140 in FIG. 9. As 
will be seen in the left portion of FIG. 9, the system will not operate 
unless the sensing pad 20 is depressed and the data signal is ready. 
If the key is not inserted in the barrel 44 and the membrane switch 24 is 
depressed and the data signal such as the spacing signal for information 
from the external source 81 is present on the data port, the system will 
go into the data I/O operation shown at 146 in FIG. 9. The data I/O 
operation is understood in the art as a protocol-based communication 
system in which data at a specified Baud rate is sent between the two 
communicating systems. The hand print on a sensing pad like the sensing 
pad 20 is then sensed as at 148 in FIG. 9 and the hand print is recorded 
in the memory 34 as at 150. 
The gun constituting this invention has certain important advantages. It 
becomes activated instantaneously on a passive basis when an authorized 
user grips the handle 14 to fire the gun. The gun is accordingly ready to 
be fired immediately after the authorized user grips the gun. Furthermore, 
as long as the authorized user is in possession of the gun, the 
identification of the authorized user cannot be altered since the 
identification is stored in the memory 34 which is internal to the gun. 
Even if the authorized user is not in the possession of the gun, the 
user's identification in the memory 34 cannot be altered as long as the 
user has the Key 41. 
The gun constituting this invention also has other important advantages. 
For example, when an authorized user has been identified and the gun has 
been prepared to be fired, the user can relinquish his grip on the gun and 
then grip the gun again for immediate firing. Provided that the time 
between the grip relinquishment and the grip tightening occurs within a 
particular period such as twenty (20) seconds, the authorized user can 
immediately fire the gun. 
There are other important advantages in the gun of this invention. The gun 
records each time that an authorized user fires the gun. The gun also 
records the authorized user who has fired the gun. The gun also records 
the print of each unauthorized user who attempts to fire the gun. The gun 
further records the time when the unauthorized user attempts to fire the 
gun. 
Although this invention has been disclosed and illustrated with reference 
to particular embodiments, the principles involved are susceptible for use 
in numerous other embodiments which will be apparent to persons skilled in 
the art. The invention is, therefore, to be limited only as indicated by 
the scope of the appended claims.