Device for the obtaining of an electric signal which is proportional to an amount of movement and therefore capable of detecting any movement or acceleration

An apparatus for detecting and signalling the presence and absence of movement of an object moving randomly in space and time has a portable transmitter carried by the moving object, such as a human operator. The transmitter transmits a carrier frequency signal so long as the operator continues his random movements. A detector associated with the transmitter detects the random movements and has sensing means which is a sensor that responds to the operator's movements and is movable randomly in three dimensions in response to the movements. The detector has a photo-responsive switch activated by the movement sensor which interrupts the emission of the carrier frequency signal when the human operator is substantially immobile and permits the transmission once the operator renews his movement. A receiver is positioned in an area for receiving the carrier frequency signal. It activates an alarm after a delay of a predetermined period of time after the carrier frequency signal is not received by it because of the interruption therefor while the operator is substantially immobile.

BACKGROUND OF THE INVENTION 
The present invention relates to a device which makes it possible to obtain 
an electric signal which is proportional to an amount of movement and 
therefore capable of detecting any movement and is suitable in particular 
for an individual signalling apparatus for the rapid detection of 
accidents. 
An individual signalling apparatus for the rapid detection of accidents has 
been devised which comprises on the one hand a transmitter carried by the 
operator which continuously gives off a high-frequency signal. This 
transmitter is controlled by a switch which interrupts and reestablishes 
the emission of the high-frequency signal in random fashion as a function 
of the movements of the operator. The apparatus further comprises a 
receiver which can be located at any place in the area of use. The 
receiver comprises a clockwork which operates continuously after every 
stop of reception of the high-frequency signal and causes the giving of an 
acoustic alarm signal after the passage of a predetermined period of time. 
The present invention concerns instruments and detectors which make it 
possible to supply an electric signal which is related to a movement and 
therefore a speed or acceleration, and in particular the apparatus 
indicated above. 
In the known devices of this type, the detection of movement is not 
programmable and operates only when the movement takes place in a 
well-defined position in space, that is to say positions of an individual 
or of a machine along preferential axes. These systems generally employ 
mercury contained in a glass tube, whose movement information is given on 
a "all-on and all-off" basis. 
SUMMARY OF THE INVENTION 
The device in accordance with the invention makes it possible to avoid 
these drawbacks. It is possible with it to detect a movement in any 
position and to have a system which gives an electric signal which is 
substantially proportional to the movement and therefore a programming of 
the amount movement which it is desired to detect. 
For this purpose, the invention concerns a device which makes it possible 
to obtain an electric signal proportional to an amount of movement and 
therefore capable of detecting any movement, suitable for an individual 
signalling apparatus for the rapid detection of accidents, comprising on 
the one hand a transmitter borne by the operator and continuously giving 
off a high-frequency signal. This transmitter is controlled by a switch 
which interrupts and reestablishes the emission of the high-frequency 
signal in random manner as a function of the movements of the operator. 
The invention further comprises a receiver which can be placed anywhere 
within the zone of use and comprises a clockwork continuously operating 
after each stop of reception of the high-frequency signal and controlling 
the giving off of an acoustic alarm signal after the passage of a 
predetermined period of time, which device is characterized by the fact 
that on the one hand it has a ball contained within a photoelectric field 
and capable of moving in space and that therefore the field received is 
proportional to the movement and that on the other hand the detection of 
the movement can be effected in space and is programmable. 
In accordance with one embodiment of the invention, the detector is 
composed of a ball which can move in a cylindrical space. This space is 
swept by a photoelectric field perpendicular to the axis of this cylinder. 
The movement of the ball causes an instantaneous variation of the field 
proportional to the amount of movement given by the ball. 
The electronic system consists of an amplification, a filter circuit which 
makes it possible to be independent of the initial condition at rest, 
which initial condition is established without movement and differs 
depending on the position of the ball in the field with respect to the 
position of the detector in space, as well as a circuit for the 
programming of the amount of movement which it is desired to detect.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The apparatus shown in FIG. 1 comprises essentially two distinct parts, 
namely on the one hand a transmitting unit 1 carried by an operator, 
possible accidents to whom must be rapidly detected and, on the other 
hand, a receiver unit 2. 
The transmitter unit 1 comprises a transmitter proper 3 connected to a 
sampler 4 and energized by a battery 5. This transmitter is connected to 
an antenna 6 of the shoulder strap type and it produces a carrier of high 
frequency, for instance of 27 MHZ. The transmitter 3 operates under the 
control of a detector 7 which closes its contact when the operator is 
moving. 
As shown in FIGS. 2 and 3, the device comprises a detector 119 composed of 
the assembly consisting of the printed circuit 102 on which there is 
mounted a transmission diode or photodiode 101 of a wavelength of between 
500 and 1200 manometers; a printed circuit 113 on which there is mounted a 
phototransistor 116; the circuits 102 and 113 are connected together with, 
between them, the elements 106, a plate of metal or other material 
provided with a hole at 107; the transparent element 108, 110 same as 106, 
111 same as 108, 112 same as 106. Between 108 and 111 there is 
incorporated a ball 109 which moves in the cylindrical passage 107 of 110. 
The assembly is held together by bolts 118 which pass through the holes 
103 and are locked by the nuts 117. 
The photoelectric field which is emitted by the photodiode 101 which is 
perpendicular to the axis formed by 107 is intercepted by the ball 109. 
The phototransistor 116 then receives a gradient of the field caused by the 
movement of the ball 109. The electric signal developed by the 
phototransistor is proportional to the movement. 
The associated electronic system (FIG. 3) then processes the analog signal 
obtained on the one hand by feeding the transmission diode via a battery 
121 and the phototransistor and the other circuits via 122 which is a 
positive or negative supply with zero referential. The electric signal of 
the gradient of the field is then amplified by an element 120 which can be 
a linear amplifier. The initial condition is extracted by a linear 
amplifier-filter 123. The circuit 124 is a linear subtracter which reduces 
the variation of the field to a fixed referential which is independent of 
the initial condition. The circuit 125 is a comparator which provides an 
electric signal upon a movement greater than that programmed by the 
element 126 which is a potentiometer which provides the comparison 
threshold between a fixed electric value and a variation of the field, and 
therefore the variable movement. 
The device which forms the object of the invention can be used in all cases 
where movement is to be detected. It can be used for the detection of the 
movement of a man for the purpose of the protection of an isolated worker, 
the detection of mechanical vibration and any system or element which is 
subject to movement. 
The receiving assembly 2 comprises a receiving antenna 8, a receiver proper 
10 and a decoder 11. It may also comprise a battery 9 and a battery 
charger 12 which can also be used to recharge the battery 5 of the 
transmitter. 
One important element of the receiving assembly 2 consists of a clockwork 
13 having several outlets. One of these outlets is connected to an 
acoustic annunciator 14, and another to a lamp 15, which are placed in 
operation after the passage of a predetermined period of time, for 
instance about 20 to 30 seconds after the stop of any reception. The 
clockwork is also connected to an on-off pilot bulb 16 and a prealarm 
pilot bulb 17 with which a push button 18 is associated. Another 
additional recocking push button 19 can be provided. 
The operation of the apparatus in accordance with the invention is as 
follows: as long as the operator is moving, the switch is closed and the 
transmitter 3 continuously gives off a high-frequency carrier of 27 MHZ. 
This switch at random interrupts the transmission of the carrier as a 
function of the movements of the operator and then causes the 
reestablishing of the transmission. The permanent stopping of the 
transmission takes place only if the operator is in a practically 
stationary position. 
In the receiving unit 2 the clockwork 13 is not engaged as long as the 
receiver 10 receives the high frequency carrier, that is to say as long as 
the operator is moving. 
On the other hand, as soon as the switch, as a result of the immobility of 
the operator, interrupts the emission of the high-frequency carrier, this 
stopping of the signal is detected by the receiver 10 and the decoder 11, 
which causes the engagement of the clockwork 13. If the stopping of the 
high frequency carrier continues for a predetermined period of time, for 
instance about 20 to 30 seconds, the clockwork 13 upon the expiration of 
this period of time gives off an alarm signal by means of the acoustic 
annunciator 14 and/or a luminous alarm by means of the bulb 15. This 
signal advises the operator that the unit 1 is no longer emitting the 
high-frequency carrier. 
If the operator is not injured, he need merely start moving again in order 
to transmit for a moment and then the clockwork 13 is automatically 
returned to zero. 
On the other hand, if the operator does not move within a first period of 
time of 20 to 30 seconds, for instance as the result of an accident, the 
clockwork 13 brings about the giving off of a general alarm which may 
include a powerful alarm bell. The receiving assembly 2 contains the 
button 18 which makes it possible to turn off the alarm. 
The electric power line is used to feed the receiving unit 2 and possibly 
to recharge the batteries. Otherwise, a charger is used. However, the 
charge life is calculated so as to make it possible to maintain full 
emission during a work shift.