Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The invention relates to an electronic detection and
transmission system for activating a remote camera or triggering
an alarm. More specifically, the invention relates to such a
system which is light sensitive.
The so-called "money-clip", which is a pressure sen-
sitive electronic device, adapted to activate a remote camera
or trigger an alarm, is well known in the art. Such money clips
are used in banks, and they are usually kept in tellers' drawers
with a stac]c of bills on top of them. The pressure of the stack
of bills keeps the circuit in the clip in an OFF condition.
When the bills are removed from the money clip, the
release of pressure puts the circuit in an 0~ condition, where-
upon it will transmit a signal to either a remote camera or an
alarm to activate the camera or trigger the alarm.
Accordingly, the bills should be removed from the clip
only when the bank is being held up. When the bills are removed
the camera will be activated to take pictures of the hold-up men.
Alternatively, an alarm could be triggered in, for example, a
nearby police station.
Such money clips have the disadvantage of being too
easily turned 0~. ~hus, if the stack of bills i9 partially moved
off the clip, then the release in pressure could needlessly
activate an alarm condition when an alarm situation does not exist.
For example, in reaching into the drawer for something, the
teller's arm or hand could accidentally brush up against the stack
o~ bills and move it. Or, in opening or closing the drawer, the
action of the moving drawer could cause the stack o~ bills to
move.
It is there~ore an object of the invention to provide
3G an electronic system which overcomes the above disadvantages.
It is a more specific object of the invention to
provide such a system wherein a small movement of the stack of
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bills will not falsely trigger an alarm condition.
It is an even more specific object of the invention to
provide such a system which is light sensitive.
It is an even more specific object of the invention to
provide such a system which is contained in a housing having a
top surface, the light sensing means being disposed below the
opening-of the top surface.
In accordance with the invention, an electronic detec-
tion and transmission system comprises: a housing having a top
surface, an opening in said top surface; light sensitive means
disposed in said housing below said opening, and a transmitter
means disposed in said houqing; said light sensitive means ~eing
connected in circuit with said transmitter means, whereby, when
said opening is uncovered and light is permitted to enter said
opening and fall on said light sensitive means, said transmitter
means will transmit a predetermined signal.
Preferably, said light sensitive means comprises a
phototransistor.
Preferably, said opening is in the center of said
top surface.
The output of said light sensitive maans may be con-
nected to the input of an amplifier, and a code generator may be
connected in parallel with said light sensitive means; wherein
said system further comprises an AND gate, the output of said
amplifier being connected to one input terminal of said AND gate;
the output of said code generator being connected to the other
input terminal of said AND gate, said transmitter means comprising
an electronic ON/OFF switch; the output of said AND gate being
connected to the control terminal of said switch, whereby, when
light falls on said light sensitive means, the signal transmitted
by said transmitter means will correspond with the code generated
by said code generator.
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The invention will be better understood by an exam-
ination of the following description, together with the accom-
panying drawings, in which:
Figure 1 illustrates the housing of the inventive
system, and
Figure 2 is a block diagram of the electronic circuit
of the system.
Referring to Figure 1, the system is contained in a
housing 1, shown in Figure 1 as an eight sided box. The actual
form of the housing is not critical, as long as the housing
includes a top surface 3 with an opening 5, and a ~ottom surface
for mounting a light sensitive means 7.
As can be seen in Figure 1, the opening 5 is at the
center of the top surface, i.e., any straight line drawn through
the opening to opposing edges will be of equal length on either
5ide of the opening, for reasons to be explained below. The light
~ensitive means which is preferably a phototransistor as well -
]~nown in the art, is disposed directly below the opening 5 so
that any light which enters the opening will fall on the photo- -
transistor. As is well known in the art, when light falls on the
phototransistor its state will change relative to its state when
it is in darkness.
Referring to Figure 2, the light sensitive means is
shown connected in serie~ with a power source, such as battery
9, and in parallel with code generator 11. Amplifier 13 amplif-
ies the output of means 7.
The output of the code generator is connected to one
input terminal of AND gate 15, while the output of amplifier 13
is connected to the other input of 15. The output of the AND
gate controls switch 17, which is the ON/OFF switch for trans-
mitter 19. Prefera~ly, the switch 17 is an electronic switch,
as well known in the art, and the switch will normally constitute
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an integral part of the transmitter, but is shown separately
here to simplify the description.
The output of the trans~itter is fed to antenna 21.
In operation, the system works as follows:
A stack of bills 23 is disposed on the top surface
over the opening 5 so as to prevent any light from entering
through the opening, leaving the phototransistor in darkness.
Under these conditions, the phototransistor will be quiescent,
and it will not provide an output signal.
As can be clearly seen, the bills would have to be
moved a substantial distance before the opening is uncovered to
permit light to enter the opening 5. As the opening has to be
uncovered to trigger an alarm condition, as will be seen below,
false alarms will not be initiated by a brush of the teller's arm
or by movement of the drawer. This is,of course, due to the fact
that the opening is substantially centrally located. However, it
will be appreciated that the opening could be somewhat offset
from the center, and most of the advantages of the inventive
system will still be obtained.
Turning to Figure 2, when the means 7 is not providing
an output, then only one input terminal to the AND gate is being
fed, so that there will be no output at the output terminal of
the AND gate. Thus, switch means 17 will not be activated ~o turn
on the transmitter 19.
When the stack of bills 23 is removed from the top sur-
face 3, for example, when the band is being held-up and the hold-
up person demands all the money in the teller's drawer, then
opening 5 will be uncovered permitting light to enter the opening
5 and to fall on the phototransistor 7. At this time, the state
of phototransistor 7 will be changed so that amplifier 13 provides
an output to thereby open gate 11 to the output of the code
generator 11.
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The output of gate 15 will then activate the swi-tch
each time it provides a signal, 50 that the transmitter will be
turned ON and OFF in synchronism with the code of the generator
11. Accordingly, the transmitter will be transmitting a coded
signal.
As above mentioned, the system can be used with a re-
mote camera. The camera, as well known, includes a receiver having
a decoder, and the receiver is designed so that the camera is
turned ON and takes photographs at predetermined intervals when-
ever the transmitted code is received, and only when this code isreceived. The coder/decoder system is used to prevent false trig-
gering of the camera from other spurious or generated electrical
signals in the vicinity. The camera, being directed to the posi-
tion in front of the teller, will take photographs of the hold-up -
person.
Instead of using a code/decode arrangement, especially
in relatively electrically quiet areas, it is possible to simply
have the transmitter and receiver tuned to a common frequency.
Again, the transmitter would provide an output signal only when
opening 5 is uncovered, and in this case, the CW signal received
at the camera receiver would be detected to provide a camera
initiating signal.
For the tuned frequency system, the parallel line of
the code generator 11, and the A~D gate 15, would not be necessary.
Instead, the output of the amplifier 13 would be fed directly to
the switch means 17 to turn ON the transmitter during an alarm
situation. The transmitter would then, as above indicated, trans-
mit a CW signal at the tuned frequency.
~ s will be appreciated, the means 7 will have to be
sensitivity adjusted taXing into account the ambient light con-
ditions of its environment. Thus, if it is in a relatively dark
drawer, it will have to be more sensitive than if it is disposed
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in a high intensity light environment.
The particular circuit elements whlch make up the
boxes in the block diagram of Figure 2 are well known in the art
and require no further description here. As will be appreciated,
all of the circuit elements are contained in housing 1 although
not so shown in Figure 1.
Although several embodiments have been described, this
was for the purpose of illustrating, but not limiting the inven-
tion. Various modifications, which will come readily to the mind
of one skilled in the art, are within the scope of the invention
as defined in the appended claims.
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