Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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FIELD OF THE INVENTION:
The present invention related to a theft prevention
apparatus for vehicles. More particularly, the present invention
relates to an apparatus which produces an alarm sound in
response to the detection of movements o~ the vehi~le ~hat ma~
be caused when a person other than the driver attempts to
steal the vehicle while it is parked.
SUMMARY OF THE INVENTION:
It is an object of the present invention to provide a
1~ theft prevention apparatus for vehicles that produces an
alarm sound in response to the detection of movements o~ the
vehicle that may be caused when a person other than the driver
attempts to steal the vehicle while it is parked. The apparatus
locks the movement detector mean~ while the vehicle is running,
to thereby prevent the set condition of a movement detector
from being disturbed due to vibrations, whereby proper
operation of the movement detector can be assured.
According to the invention, the movement detector utilizes
the mechanism of a moving-coil type meter, comprising a pointer
having on its distal end a weight and pivotally supported at
its base portion b~ à spiral spring, the base portion of the
pointer supporting a coil thereon, and magnet poles disposed
on either vertical sides of the pointer base portion. While
the vehicle is stopped, the detector can detect unusual
movements of the vehicle to generate an alarm signal current;
and while the vehicle is running, the coil on the pointer base
portion is supplied with a current ~rom an external source to
maintain the pointer immovable, i.e., in a fixed position.
The above and other objects, features and advantages of
the present inv~ntion will become apparent from the following
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description taken in conjunction with the accompanying
drawings which illustrate a preferred embodiment of the
invention, by way of example.
BRIEF DESCRIPTION OF THE DRAWINGS:
Figure 1 is a circuit dia~ram in block form o a theft
prevention apparatus constructed in accordance with the
present invention;
Figure 2 is a front elevational view of a movement
detector to be employed in the theft prevention apparatus;
~igure 3 is a side elevational view of the movement
detector shown in Figure 2; and,
Figure 4 is a view showing a conventional movement
detector.
DESCRIPTION OF THE PRIOR ART:
There have been known theft prevention apparatus that
can produce an alarm sound upon detection of unusual movèments
of a vehicle while it is parked.~ Figure 4 of the accompanying
drawings shows a conventional movement detector used in one
such theft prevention apparatus.
The movement detector comprises a base plate 43 and a
movable plate 44 that are spaced from each other and have
confronting contacts 41l42 thereon. When the movable plate
44 is moved up and down due to the action of a weight 45
attached to a distal end of the movable plate 44, the contacts
41,42 are momentarily closed, whereupon the movement can be
detected by the frequency of the closed states of the contacts
41/42. An adjustment screw 46, when turned, changes the
distance between the contacts 41~42 so as to adjust the
sensitivity of movement detection.
~ne of the problems with such prior movement detectox
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is that sensitivity adjustment is dif-icult to be done wi-th
the screw 46; that is, it is difficult to firld out for cer-tain
how wide the distance between the contacts should be for -the
detection of attempts to steal the vehicle. Further, the
distance between the contacts even iE correctly set initially,
tends to be varied due to vibrations as the vehicle is running.
Accordingly, thelprior movement detector does not have
stable and reliable operation.
DESCRIPTIO~ OF TH~ PREFERRED EMBODIM~NT:
As shown in Figure 1, a theft prevention apparatus 1
according to the present invention generally comprises a
main section 2 equipped with a radio 31 and a receiving
antenna 32 for the radio and adapted to be mounted on a
vehicle such as an automobile, and a receiver 3 which is
separate from the main section 2. The main section 2 has a
movement detector 4, which as shown in Figures 2 and 3, is
constructed of a mechanism utilizing the principles of a moving-
coil type meter. More specifically, the movement detector 4
has a pointer 5 having on its distal end a weight 6, which is
movable up and down along an outer surface 4a of the detector
4. The pointer 5 is pivotally supported by a shaft 7 attached
to a base portion 5a of the pointer, the pointer 5 being
pivotable about the shaft 7. A spiral spring 8 is disposed
axound the shaft 7 and acts between the sha~t 7 and one end
of the base portion 5a of the pointer, so that the pointer 5
is normally directed horizontally. The movement detector
is calibrated so that when it is mounted on the vehicle,
the pointer 5 will be directed horizontally on de~energization
of the detector. The move~ent detector 4 is preferably
mounted beneath the dashboard of the vehicle.
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Mounted on the base portion 5a of the pointer 5 is a
coil 9 with its terminal ends 9a, 9a disposed for external
connection. A pair of n~rth and south poles 10, 10 of a
magnet are loca-ted upwardly and downwardly of the coil 9,
respectively.
With such an arrangement, the movement detector ~
can detect slight movements in such a manner that when the
pointer 5 becomes slightly out of its horizontal reference
position under the influence of applied motion, there will be
generated a voltage across the termainl ends 9a, 9a in
response to the angular movement of the pointer 5. ~ccordingly,
sensitivity adjustment can easily be effected and stable
sensitivity can be maintained at all times.
The movement detector 4 has its output connected to
an amplifier circuit 11 that is coupled to a signal switch
12, to which there is connected a high-frquency transmitter 13.
When the pointer 5 is angularly moved through a predetermined
angle, the detector 4 produces a voltage for actuating the
signal switch 12, which then enables the high-frequency
transmitter 13 to generate an alarm signal of a high frequency.
The high-frequency transmitter 13 is connected to an adjustment
device 14 for varying the frequency or tone of a transmitting
signal so as to prevent interference with alarm signals
produced by similar apparatus 1.
The main section 2 also has a pair of switches 16,17
which are ganged together by means of a relay 15. When the
switch 16 has its movable contact in the position of -the
solid line by detachment of the receiver 3 from the main
section 2, the relay 15 is energized, whereupon the movable
contact of the switch 17 is maintained in the solid line
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position, thereby connecting the high-frequenc~ transmitter 13
to the antenna 32. When the movable contac-t of -the switch 16
is in the position of the dot-and-dash line by attachment
of the receiver 3 to the main section 2, the relay 15 is
de-energized to cause the movable contact of the switch 17
to move to the dot~and-dash lineposition, thereby connecting
the radio 31 to the antenna 32.
When the movable contact of the switch 16 is in the dot-
and-dash line position, it allows a voltage of 12V from the
battery of the vehicle to be applied via an automatic
adjustment circuit 18 across the terminals 9a, 9a of the
movement detector 4. An electric current then flows through
the moving coil 9, biasing the point 5 to one side against
wobbling movement due to vibrations that take place while
the vehicle is running.
The receiver 3 is preferably incorporated in a pocket-
sized carry-on buzzer, comprising a receiving antenna 19, an
amplifier circuit 20, a signal switch 21, a loudspeaker 22,
and a battery 23, the receiving 3 being attachable to the
main section 2 of the apparatus 1. When the receiver 3 is
not attached to the main section 2, the loudspeaker 22
produces an alarm sound in response to the reception of an
alarm signal transmitted via the antenna 32 from the main section
2. Conversely, when the receiver 3 is attached to -~he main
section 2, the movable contact of the switch 16 is caused
to be in the dot-and-dash line position, and the receiver 3
is connected via the switch 16 to the battery of 12V, which
enables the battery 23 to be charged.
When a driver gets off the vehicle having the apparatus 1
equipped, with .the receiver 3 in his hand, the pointer 5 of
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the movement detector 4 becomes freely movable. Movements
of the vehicle that may be caused by a person attempting
to steal it, cause the pointer 5 to move; whereupon the movement
detector 4 becomes actuated to enable the hi.gh-Ere~uency
transmitter 13 to transmit an alarm signal via the antenna 32,
and then the receiver 3 upon receiving such alarm signal
genera.tes an alarm sound via the loudspeaker 22. The driver
i5 now aware of the fact that the vehicle is under the attack
of a thief, and can immediately do something necessary to
prevent the theft.
While the vehicle is being driven, the receiver 3 is
mounted on the main section 2 of the apparatus 1. Therefore,
the pointer 5 of the movement detector 4 is fixed in position,
with the result that the movement detector 4 will not be
energized even if the vehicle is subjected to vibrations while
running. At the same time, the battery of the receiver 3
can be charged, and the radio 31 can receive radio ~aves through
the antenna 32.
Although the present invention has been shown applied
to a vehicle with the radio 31 and the antenna 32, the
invention is also applicable to vehicles with other equipment.
The receiver 3 may be dispensed with, and the main section 2
of the apparatus may have suitable provision for producing an
alarm sound. For instance, as indicated in an imaginary line
in Figure 1, in case that a loudspeaker 22-1 is inseparably
connected to the main section 2, the main section can produce
an alarm sound wi-th no use of the separate receiver 3.
The movement detQctor 4 is not limited to a movi.ng-coil
type structure, but may be of other structures of similar
function. The direction of angular movement of the pointer
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5 may be other than vertical depending upon the type of
vehicles.
It should be understood that various changes and
modifications can be made in the preferred embodi.ment without
departing from the scope of the appended claims.
