Emergency deceleration warning device

Emergency deceleration warning devices which may also be manually activated to provide a warning in situations where abnormal deceleration is not involved. The disclosed devices are self-contained units which include: (1) a flasher which is highly visible, even in bright daylight; (2) a circuit for turning the flasher on and off; and (3) a simple, enclosed decelerometer for enabling the flasher-operating circuit when a vehicle equipped with the warning device is decelerated at an abnormal rate.

The present invention relates to warning devices and, more particularly, to 
novel, improved devices for visually warning others that a vehicle 
equipped with the device is decelerating at an abnormal rate and may 
accordingly pose a clear and present danger. As employed herein, "abnormal 
deceleration rate" and similar terms are intended to mean collisions and 
other impacts as well as panic stops and other decreases in speed which 
might pose a danger to a following vehicle or vehicles. 
In another aspect, the present invention relates to visual warning devices 
of the character just described which can also be turned on manually or in 
some other manner to warn of danger in circumstances in which the vehicle 
equipped with the device is not decelerating at a rapid enough rate to 
activate the device. 
BACKGROUND OF THE INVENTION 
Warning devices that are triggered or turned on by more rapid than normal 
deceleration of a vehicle are disclosed in U.S. Pat. Nos. 3,559,164 issued 
Jan. 26, 1971, to Bancroft et al., for VEHICULAR DECELERATION SAFETY 
CIRCUIT MEANS; 3,760,353 issued Sep. 18, 1973, to Hassinger for EMERGENCY 
VEHICULAR WARNING SYSTEM; 3,846,749 issued Nov. 5, 1974, to Curry for 
VEHICLE BRAKE LIGHT CONTROL SYSTEM; 4,258,353 issued Mar. 24, 1981, to 
Carlson for VEHICLE ACCELERATION/DECELERATION WARNING SYSTEM; and 
4,357,594 issued Nov. 2, 1982, to Ehrlich et al. for VEHICULAR HAZARD 
WARNING SYSTEM. 
The Bancroft system has the disadvantage that it is not a self-contained 
unit but is instead designed to be incorporated in the brake light circuit 
of the vehicle in which it is installed. This can be a comparatively 
difficult matter. 
In addition, the deceleration sensing component of the Bancroft et al. 
device is a pendulum which is exposed and therefore subject to damage and 
misalignment. Furthermore, that pendulum operates an also exposed 
microswitch which is subject to wear and to damage by the fine, erosive 
particles stirred up by a moving vehicle. 
Another disadvantage of the Bancroft et al. arrangement is that visual 
warning of vehicular deceleration is given by turning a conventional 
incandescent bulb on and off. This can only be done at a comparatively 
slow rate. Consequently, the visual warning display may not make it 
obvious to an observer that a dangerous situation exists. 
Still another significant disadvantage of the Bancroft et al. device is 
that the pendulum which triggers the device is so designed and oriented 
that a mere sharp bump in a road, for example, could displace that 
pendulum enough to close the associated microswitch and turn the visual 
warning display on. This would be annoying to the driver of a following 
vehicle, at best. More likely, this would create a danger by falsely 
indicating that a panic stop was being made. 
Still another disadvantage of the Bancroft et al. device is that the visual 
warning display remains on only so long as deceleration is severe enough 
to effect a microswitch-closing displacement of the switch-operating 
pendulum. Consequently, in the event of a short, but severe, deceleration, 
the visual warning display might not be on long enough to clearly indicate 
to an observer that a panic stop was being made. 
Finally, there is no provision for manually operating the visual warning 
display of the Bancroft et al. device. This is a disadvantage because 
there are many situations not involving panic stops, such as a stalled 
vehicle, in which a visual warning display can also be employed to 
advantage. 
Like that disclosed by Bancroft et al., the Hassinger system employs a 
visual warning display with conventional incandescent filaments. The 
Hassinger device may, therefore, likewise not prove capable of being 
turned on and off fast enough to provide a clear warning of a present 
danger. 
Another disadvantage of the Hassinger system is that the control circuit 
for its visual warning display is enabled by a mercury switch. Switches of 
that type have the disadvantage in vehicular applications that the mercury 
tends to break up when the vehicle goes over a hard bump, for example, or 
is subjected to vibration on a dirt or other rough road. Once this occurs, 
the switch may stay on when it should turn off. Conversely, it may 
thereafter not come on when it should. 
In addition, the Hassinger unit is designed to be mounted under the dash of 
the vehicle in which it is installed. This area is notoriously difficult 
to reach in a modern automobile. It would accordingly be difficult and 
expensive to install the Hassinger system in such a vehicle. 
Furthermore, the Hassinger unit must be manually reset. This is a 
significant disadvantage because the device will be inoperative in a 
subsequent dangerous situation if the vehicle operator forgets to reset 
it. 
In addition, the Hassinger device has a number of mechanical parts 
including pins, springs, adjustment screws, etc. These are subject to 
partial or total failure. In addition, it would be difficult and 
burdensome to make those adjustments after installation which are required 
for the Hassinger device to operate properly. Finally, like Bancroft et 
al., Hassinger makes no provision for manually operating the visual 
warning display of his device in circumstances which pose a danger but do 
not involve abnormal deceleration. 
Carlson discloses yet another device which has the drawback that its visual 
warning display has an incandescent filament. 
Also, the Carlson device is quite complicated and requires special wiring. 
Consequently, an actual unit of the character proposed by Carlson would be 
expensive to produce and install. And its complexity would make it less 
than optimally reliable. 
Furthermore, the Carlson device is yet another one which must be manually 
reset. In his case, however, the situation is exacerbated because the 
visual warning display will continue to operate until the decelerometer is 
manually reset. Consequently, the visual warning display continues to 
flash, perhaps indicating that an emergency situation exists, long after 
the emergency has ended. This is particularly important because the driver 
of the vehicle may not be aware that the device is continuing to operate. 
Yet another disadvantage of the Carlson system is that it employs a trigger 
relay to control the operation of the visual warning display. This is a 
drawback because relays of that character are unreliable when used in 
vehicles in which they are subject to shock and vibration. 
The Curry device is yet another one which employs the brake lights of the 
vehicle in which it is installed to provide a visual display warning. 
Consequently, the Curry device has the same disadvantages as other warning 
devices employing that scheme. 
Also, at least in part, the deceleration indicative input of the Curry 
device is taken from the speedometer cable of the vehicle in which the 
device is installed. This arrangement has the disadvantage that it is not 
capable of taking into account the nature of the terrain on which the 
vehicle equipped with the device is operating. For example, a much lower 
rate of deceleration is required to send a vehicle descending a steep hill 
into a skid than is necessary to cause that vehicle to skid while 
ascending the same hill. The speedometer cable-derived input of the Curry 
device is not capable of so altering the operation of that device's 
display-controlling circuitry to take factors such as the one just 
identified into account. 
Furthermore, the Curry device employs extensive wiring and several 
pick-ups. As a practical matter, it could therefore only be installed in a 
vehicle while that vehicle was being manufactured. Thus, the Curry device 
has the disadvantage that it probably would not be practical to install in 
an already manufactured vehicle even at the dealer level. 
An extremely complicated vehicular warning device is disclosed in the 
Ehrlich et al. patent. That device has a large number of mechanical 
components including four sensors, mechanical clutches, etc. As a result, 
the Ehrlich et al. device would be expensive to manufacture and to 
maintain. It would be less than optimally reliable because of the failure 
susceptibility of its many mechanical components. 
In fact, the Ehrlich et al. device is so complicated that it requires 
extensive adjustments after the device is installed. This could make 
installation impractically expensive by placing it beyond the reach of the 
average vehicle owner. 
Furthermore, the Ehrlich et al. device would necessarily have a relatively 
slow response time: (1) because of the above-mentioned mechanical 
components, and (2) because the turning on of the visual warning display 
is controlled by a relatively slow acting, mechanical relay. 
In addition, the Ehrlich et al. device is yet another one which utilizes a 
visual warning display with an incandescent filament. It, too, has the 
above-discussed disadvantages appurtenant to that type of display. 
Yet another disadvantage shared in common by those above-discussed systems 
employing low mounted, dual vehicular brake lights as a visual warning 
display is that an observer able to see the light at only one side of a 
vehicle may mistakenly take the flashing display for a turn signal rather 
than a warning of a present danger. 
SUMMARY OF THE INVENTION 
We have now invented, and disclosed herein, certain new and novel emergency 
deceleration warning devices which do not have the disadvantages of those 
prior art warning devices disclosed above and which, moreover, have a 
number of significant features not possessed by those devices. 
Generally speaking, our novel emergency deceleration warning device is a 
self-contained unit comprising: (1) a high speed flasher or visual warning 
display, (2) a circuit for turning the flasher on and off, and (3) a 
simple, enclosed decelerometer for enabling a flasher-operating circuit 
when a vehicle equipped with the warning device is decelerated at a rate 
exceeding that associated with normal braking. This unit is designed to be 
prominently mounted on the rear deck of an automobile or at the top of a 
station wagon or hatchback rear window. The flasher-operating circuit of 
the device is designed to be connected directly to the hot terminal of the 
vehicle's battery and to the vehicle ground. 
One above-alluded-to advantage of the novel emergency warning devices 
disclosed herein is that the flashers we employ, typically consisting of a 
xenon-filled bulb, are capable of emitting light at a high intensity only 
a few milliseconds after they are turned on. Consequently, an almost 
instantaneous warning can be given when an emergency arises. Also, these 
visual warning devices can be flashed at a rate which eliminates any 
confusion between them and turn signals, brake lights flashed off and on 
by the pumping of vehicular brakes, etc. 
Also, our novel devices give a warning of a dangerous deceleration whereas 
normal brakelight systems do not. In addition, our novel devices will give 
a warning of dangerous deceleration even when vehicles in which they are 
incorporated are operated by those unfortunately numerous drivers who 
habitually ride their vehicle's brakes and therefore keep the vehicle's 
brake lights turned on whether or not it is slowing down. 
Another advantage of our novel devices, attributable to the type of visual 
warning display we employ, is that the flasher-emitted light is of a 
character which makes it highly visible even in the brightest sunlight. 
In view of the attributes of the visual warning devices just described, 
there is little chance that the warning they afford will not be seen or 
that it will be confused with a different warning signal. 
In conjunction with the foregoing, it is another feature of our novel 
emergency deceleration warning devices that the rate at which the visual 
warning display is turned on and off can be adjusted. This makes it 
possible to adjust the flash rate to a distinctive one without making this 
rate so fast that the human eye cannot distinguish individual flashes. 
Yet another advantage of our novel emergency deceleration warning devices 
is their mechanical reliability. This reliability is obtained: (1) by 
employing solid state circuitry to turn the visual warning display on and 
off, (2) by a novel design which requires only a single sensor to provide 
deceleration information to that circuitry and therefore has a minimum 
number of moving and other mechanical parts, and (3) by the self-contained 
design of the device. This self-contained design promotes reliability as 
does the fact that the visual warning display-operating circuit is wired 
to the battery of the vehicle in which the device is installed. With this 
novel type of hook-up, our novel warning device can continue to operate 
even if the brake light, turn signal, and/or emergency flasher systems of 
the vehicle fail. 
Only three (or at most four) leads are required to hook up the novel 
emergency deceleration warning devices disclosed herein. Moreover, even 
that small number of wires suffices to hook up both: (1) the visual 
warning display of the device, and (2) more conventional lamps included in 
the device and intended to be wired into the brake light system of the 
vehicle in which our device is installed to provide an additional highly 
visible warning when the vehicle's brakes are applied as required by the 
Department of Transportation on 1985 and later automobiles. 
Also, because our novel emergency deceleration warning devices are 
extremely simple, have a minimum number of moving and other mechanical 
parts, and are self-contained, they are inexpensive to produce and have a 
long service life. 
A related advantage is that, unlike prior art devices such as that 
disclosed in the above-discussed Ehrlich et al. patent, adjustment and 
debugging of the device are not required after installation. 
Another important, safety-related feature of our novel vehicle deceleration 
warning devices is that the visual warning display is automatically 
activated to provide a warning when the vehicle equipped with the device 
is turned over or tipped at an angle greater than that is assumes under 
normal operation. This could occur, for example, if the vehicle is rolled 
over or runs off the road into a ditch. 
In conjunction with the foregoing, our novel deceleration warning devices 
can also be turned on by a typically dash-mounted, manually operable 
switch. This switch is employed to enable the visual warning display 
operating circuit allowing the warning device to function in a manner akin 
to or in conjunction with an emergency flasher system at a slower rate of 
one flash per second. At the same time, it provides a more visible warning 
than a conventional emergency flasher system does. 
Yet another advantage of our novel emergency deceleration warning device is 
that it automatically compensates for the change in deceleration that 
might cause a skid as the vehicle in which it is installed travels up or 
down a steep hill. Also, it can be adjusted to compensate for the surface 
over which the vehicle equipped with it is traveling; i.e., for rough and 
bumpy surfaces, wet surfaces, snowy and icy surfaces, etc. 
Also, a sonar or other type speed-to-distance sensor may be readily 
attached to automatically trigger the visual warning display if a preset 
distance-to-speed ratio between our equipped vehicle and a following 
vehicle is violated. 
Another, and also significant, feature of our invention is that accessories 
which will provide still other useful inputs and outputs of information 
may be readily added. For example, a deceleration responsive signal which 
can be decoded and thereafter employed to automatically adjust the device 
and compensate for different road surfaces can readily be added. So can an 
output which could be activated with the visual warning display in the 
event of an accident to transmit an emergency message to the appropriate 
authorities. 
Another, and also significant, feature of our invention is a novel circuit 
which insures that the visual warning display remains on for at least a 
preselected, minimum length of time after it is first turned on. This is 
important in situations such as those involving a brief, but extremely 
rapid, deceleration. Absent activation of the visual warning display for 
the selected length of time, that display might not remain on for a 
sufficient length of time to provide a clear warning. Of course, if the 
deceleration (or other emergency) lasts longer than the selected minimum, 
the visual warning display will continue to be activated for as long as 
the deceleration of the vehicle exists plus five seconds. 
Also, our novel emergency deceleration warning devices are equipped with a 
novel thermal overload circuit which keeps the device from failing from 
overheating but nevertheless allows the visual warning display to continue 
to operate with only brief interruptions in which the temperature 
sensitive components of the device cool off. Associated circuitry, 
however, insures that the visual warning display remains on for a long 
enough period to convey an adequate warning (typically five seconds) even 
if the thermal protection is activated. 
Also, our novel emergency deceleration warning devices are equipped with a 
novel threshold voltage shutoff circuit which keeps the device from 
running the battery below a predetermined amount of charge needed to start 
the vehicle. Associated circuitry, however, insures that the visual 
warning display remains on for a long enough period to convey an adequate 
warning (typically five seconds) even if the minimum threshold is reached. 
OBJECTS OF THE INVENTION 
From the foregoing, it will be apparent to the reader that the primary 
object of the present invention resides in the provision of novel, 
improved emergency deceleration warning devices for automobiles and other 
vehicles. 
Other also important but more specific objects of the invention reside in 
the provision of emergency deceleration warning devices as described in 
the preceding object: 
which provide a visual warning display that is visible under the most 
adverse conditions and which is unlikely to be confused with other warning 
signals; 
in which, in conjunction with the preceding object, the visual warning 
display is a high intensity gas discharge tube which can be operated at a 
factory or user adjustable rate; 
which are mechanically reliable; 
which, in conjunction with the preceding object, employ a solid state 
circuit to turn the visual warning display on and off and which can have a 
single decelerometer and an absolute minimum of moving parts; 
which are self-contained units with visual warning display operating 
circuits that are designed to be wired directly to the batteries of the 
vehicles in which they are installed; 
which are also capable of providing a visual indication of normal braking; 
which will continue to operate even though the brake light, turn signal, 
and/or emergency flasher systems of a vehicle equipped with the device 
should fail; 
which are relatively inexpensive to produce; 
which have a long service life; 
which are simple to install and do not require adjustment after 
installation; 
which include a visual warning display that is activated to flash a warning 
when the vehicle in which it is installed is turned over or tipped at an 
angle greater than that it is designed to assume during normal operation; 
which can be activated manually and are therefore capable of being employed 
to warn of a stalled vehicle or other emergency hazard not involving 
abnormal deceleration; 
which can be adjusted to compensate for the character of the surface over 
which the vehicle equipped with the device is traveling; 
which automatically compensate for the steepness of the terrain over which 
the vehicle equipped with the device is traveling; 
which are versatile in that accessories which will provide yet other 
advantages can be readily added; 
which are so designed as to provide a visual warning for at least a minimum 
period of time upon being activated; 
which have a thermal protection system that allows the device to continue 
to operate, albeit with momentary interruptions, in circumstances in which 
heat sensitive components of the device may tend to become overheated; 
which has a slower flash mode in which the current drawn from the vehicle 
battery is reduced to provide a longer potential warning period; and 
which will operate until the battery voltage drops to a threshold voltage 
and then shuts off so that the battery will retain enough charge to start 
the vehicle engine. 
Other important objects and features and additional advantages of the 
invention will be apparent to the reader from the foregoing and the 
appended claims and as the ensuing detailed description and discussion of 
the invention proceeds in conjunction with the accompanying drawing.

DETAILED DESCRIPTION OF THE INVENTION 
Referring now to the drawing, FIG. 1 depicts an automobile 20 equipped with 
an emergency deceleration warning device 22 embodying, and constructed in 
accord with, the principles of the present invention. Typically, warning 
device 22 will be mounted on the rear deck of an automobile such as that 
shown in FIG. 1 by an appropriate bracket (not shown). 
In the case of a hatchback or station wagon, the warning device can instead 
be installed in the location commonly employed for the third light of the 
vehicle braking system. It can be affixed to the vehicle in same manner as 
the latter. 
Referring now primarily to FIGS. 2 and 3, the major components of emergency 
deceleration warning device 22 are: (1) a decelerometer 24; (2) a high 
intensity discharge, xenon-filled bulb 26 which is turned on and off 
(i.e., flashed) by a circuit 27 containing components printed and/or 
mounted on a diagrammatically illustrated board 28; and (3) a conventional 
incandescent bulb 30. These components are mounted in a casing 32 which 
has a base 34, side walls 36 and 38, a rear wall 40, a top wall 42, and a 
red lens 44 which doubles as the front wall of the casing. 
The circuit 27 alluded to above turns the xenon-filled bulb or flasher 26 
on and off to warn motorists following vehicle 20 that the vehicle is 
decelerating at a faster than normal rate detected by decelerometer 24. A 
flash rate of ten cycles per second will typically be employed to 
distinguish the visual warning given by device 22 from that generated by a 
turn signal or by the brakes of vehicle 20 being pumped repeatedly to turn 
brake lights 46 and 48 on and off. A gaseous discharge-type device such as 
the illustrated xenon-filled tube 26 is employed in our novel emergency 
deceleration warning device 22 rather than a conventional incandescent 
bulb because of the xenon flasher's faster response time and because it is 
much more visible in sunlight and other brightly illuminated settings. 
Incandescent bulb 30 is wired in parallel with the lower mounted brake 
lights 46 and 48 of vehicle 20 and is therefore turned on and off with the 
latter. Thus, emergency deceleration warning device 22 also doubles as, 
and meets the requirements of, now federally mandated, high mounted, third 
brake lights. 
Referring now to FIGS. 3-6, the decelerometer 24 employed to measure the 
deceleration of vehicle 20 is supported from the side of the base 36 of 
warning device casing 32 by an L-shaped bracket 50. That bracket has a 
base 52 and a vertical leg 54. A pendulum 56 is pivotably supported, at 
its upper end, from the vertically extending leg 54 of bracket 50 by a 
pivot member 58. This pivot member extends through bracket leg 54, a 
spacer 60, and the upper end of pendulum 56. Various washers 62 . . . 68 
are provided so that pendulum 56 can swing about pivot axis 70 without 
binding; and a conventional retainer 71 is employed to hold together the 
assembly of pivot member 58, spacer 60, and pendulum 56. 
Absent deceleration, pendulum 56 is supported at a selected angle from the 
vertical (typically, ca. 26.degree.) by a stop or rest 73. That stop is 
fixed to the vertically extending leg 54 of bracket 50 toward the lower 
end of the latter. 
In this illustrated position, pendulum 56 interrupts a beam of infrared or 
visible radiation which otherwise can pass from the emitter 74 to the 
detector or transducer 76 of an emitter/detector unit 78. That unit is 
mounted on the base 52 of bracket or support 50. 
As vehicle 20 decelerates, pendulum 56 rotates about pivot axis 70 in the 
direction indicated by arrow 82 in FIG. 4 to an extent indicative of the 
deceleration rate. If that rate is high enough to pose a danger to a 
following vehicle, pendulum 56 will swing in the direction indicated by 
arrow 82 out of the line-of-sight between infrared radiation emitter 74 
and detector 76. This causes detector 76 to output an electrical signal. 
That signal is employed to enable circuit 27, which thereupon turns gas 
discharge lamp 26 on and off at the selected flash rate to warn following 
vehicles that an emergency condition has arisen. 
Circuit 27 remains on until the rate of deceleration of vehicle 20 drops 
below the set rate. At this point, pendulum 56 swings back towards 
pendulum rest 73 to once again interrupt the beam of infrared radiation or 
visible light from emitter 74. Detector 76 thereupon ceases to generate an 
electrical output. This disenables circuit 27; and flasher 26 goes off 
after it has continued to flash for a long enough period (typically 5 
seconds) to clearly warn those vehicles following vehicle 20 that the 
latter has been braked at an abnormal rate. 
The angle at which pendulum 56 is supported by pendulum rest 72 can be 
adjusted to change the swing arc and, therefore, the deceleration required 
for pendulum 56 to clear the beam of radiation from emitter 74 and thereby 
allow detector 76 to enable visual warning display-operating circuit 27 in 
the manner discussed above. This is typically done to match the operation 
of emergency deceleration warning device 22 to the condition of the road 
or other surface over which vehicle 20 is traveling. For example, lighter 
braking is required to produce an imperiling skid or other dangerous 
condition that should be warned of on a wet, snowy, or icy surface then is 
required on a dry surface. Therefore, warning device 22 is preferably 
adjusted when vehicle 20 is traveling over one of those more slippery 
surfaces so that a lower rate of deceleration will cause circuit 27 to be 
enabled. 
The adjustment just discussed is provided by an adjustment mechanism 83 
which includes a shaft 84 supporting the assembly 86 of bracket 50, 
pendulum 56, pendulum rest 73, and emitter/detector unit 78 from the side 
wall 36 of emergency deceleration warning device casing 32. Shaft 84 is 
fixed to the vertical leg 54 of bracket 50 in any convenient fashion which 
requires that the bracket rotate with the shaft. The shaft is also fixed 
to casing side wall 36, in this case by retainers 88 and 90 on opposite 
sides of the casing wall. These retainers also generate sufficient 
friction between the shaft and the casing wall 36 to retain shaft 84 in 
the position to which it is rotated. 
Rotation of shaft 84 is effected by a knob 92 fixed to the outer end of the 
shaft on the exterior side of casing 36. A dial (not shown in FIG. 5 for 
the sake of convenience but identified by reference character 94 in FIG. 
3) may be fixed to shaft 84 in concentric relationship with shaft 84 to 
facilitate the adjustment of decelerometer 24. This dial can be calibrated 
in terms of G force or, alternatively, in terms of road surface by 
employing designations such as "dry," "bumpy," "wet," and "snowy or icy." 
We pointed out above that the circuit 27 shown in FIG. 11 is enabled, 
resulting in flasher 26 being turned on and off at a typical ten cycle per 
second rate, when vehicle 20 decelerates at a fast rate. This is because 
abnormally rapid deceleration causes pendulum 56 to swing in the direction 
indicated by arrow 82 in FIG. 4 to the extent that radiation from the 
emitter 74 of unit 78 falls on detector 76 and causes the detector to 
generate an enabling electrical input for circuit 27. 
Now referring again to the drawing, FIG. 11 depicts in more detail a 
preferred emitter/detector unit 78 for supplying the electrical pulse 
required to enable circuit 27. The major components of emitter/detector 
unit 78 include: (1) photo emitter 74, (2) photo detector 76, and (3) 
three resistors R106, R108, and R110. These are, respectively: a current 
limiting resistor for photo emitter 74, a protective device for photo 
detector 76, and a biasing resistor for the photo detector. 
As is also shown in FIG. 11, photo detector 76 is connected across, and is 
always enabled by, plus 12 volt power supply (not shown). This power 
supply will typically be an automobile or other vehicular battery. 
We pointed out above in conjunction with the decelerometer illustrated in 
FIGS. 4-6 of the drawing that photo detector 76 outputs an electrical 
pulse when the active element of the decelerometer is displaced to an 
extent which allows the beam of light from photo emitter 74 to fall upon 
the detector. This decelerometer element is illustrated diagrammatically 
in FIG. 11 and identified by reference character 112 because it does not 
necessarily have to be a pendulum like that identified by reference 
character 56. 
The electrical output signal from photo detector 76 appears at terminal 
114, which is also shown in FIG. 12. Turning now to the latter figure, the 
photo detector output is routed from terminal 114 through diodes 116 and 
118 and a biasing resistor R120 to the base of a transistor 122. Diode 116 
isolates the detector unit 76 shown in FIG. 11. Diode 118 similarly 
isolates certain accessory inputs of circuit 27 which are described in 
detail hereinafter. 
Connected in parallel with resistor R120 is a second biasing resistor R124. 
Two additional biasing resistors R126 and R128 are connected in series 
between the collector of transistor 122 and the base of a second 
transistor 130. 
As a consequence, the output from photo detector 76 turns on transistors 
122 and 130. That connects the emitter of transistor 130 through a fuse 
131 to the plus 12 volt power source. As indicated above, that power 
source is typically the battery of the vehicle in which emergency 
deceleration warning device 22 is installed or the ignition side of the 
ignition switch. 
This plus 12 volt signal is applied to input terminals or pins 12, 11, and 
8 of a solid state switching regulator 132 such as a TL494 or a TL594. 
Such regulators are available from a number of manufacturers including 
Texas Instruments. Switching regulator 132 is employed in transforming the 
plus 12 volt input pulse to a plus 200 volt output signal required to 
operate the high energy discharge tube or visual warning display 26. 
A bypass capacitor C133 is connected between these pins and ground to 
stabilize the plus 12 volt enabling signal routed to switching regulator 
132 from transistor 130. 
An indicator lamp 134 is also connected across inputs 12, 11, and 8 through 
a current limiting resistor R136. This lamp accordingly turns on when a 
panic stop or other abnormal deceleration of the vehicle equipped with 
emergency deceleration warning device 22 is made. This provides an 
indication that circuit 27 has been enabled and the threshold G-force has 
been reached. 
Circuit 27 can also be enabled and indicator lamp 134 turned on by any one 
of the accessory inputs mentioned briefly above. These are identified by 
reference characters 138, 140, 142, and 144 in FIG. 12. 
These inputs respectively feed into diodes 139, 141, 143 and 145, isolating 
each of the inputs from each other. 
The first of these inputs, 138, is from the emergency flashers of vehicle 
20. It causes visual warning display 26 to be flashed on and off when the 
emergency flashers of vehicle 20 are turned on. 
Input 140 is from the above-referred to, dash-mounted switch. Input 140 
allows circuit 27 to be enabled manually and visual warning display 26 
activated in the circumstances discussed above. 
The third input 142 is from the back-up light circuit of vehicle 20. A 
signal from this input results in circuit 27 being activated and providing 
a warning when vehicle 20 is backing up by flashing visual warning display 
26 on and off. 
Finally, the fourth input 144 may be from the emergency light system of a 
police vehicle, ambulance, etc. when the device is used in such vehicles. 
Inputs may be taken from still other warning systems of the vehicle 
equipped with emergency deceleration warning device 22 to optimize that 
device for a particular application. 
The enabling of circuit 27 via the detector unit 78 shown in FIG. 11 will 
typically cause visual warning display 26 to be turned on and off at a 
rate of ten cycles per second. In contrast, if that circuit is enabled via 
any one of the inputs 138, 140, 142, or 144, display 26 will instead 
typically be turned on and off at a slower rate of one cycle per second. 
This is done for several reasons--(1) to conserve electrical energy; (2) 
to distinguish the display generated in an abnormal deceleration situation 
from the other, just-discussed warnings that display 26 might be employed 
to provide; and (3) to extend the length of time for which circuit 27 can 
be operated indefinitely without becoming overheated. This is important 
because a longer warning will typically be in order in the just-described 
circumstances than is needed in an emergency deceleration situation. 
Referring still to FIG. 12, with the plus 12 volt input signal applied to 
switching regulator 132, plus 12 volt, sequential pulses appear 
alternately at output pins 10 and 9 of the switching regulator. These 
pulses are routed through current limiting resistors R146 and R148 and 
biasing resistors R150 and R152 to transistors 154 and 156. Those 
transistors convert the sequential signals appearing at pins 10 and 9 of 
the switching regulator to an alternating 24 volt peak-to-peak signal 
(referenced to A and B in FIG. 12). 
The output from the transistor circuit just described is applied across the 
primary 158 of a transformer 160 wired in a push-pull configuration. Here, 
the output signals from transistors 154 and 156 are converted to the 
higher voltage needed to operate visual warning display 26. Typically, 
this voltage will be alternating 400 volts peak-to-peak with respect to 
reference points C and D. 
A bypass capacitor C160 is connected from the plus 12 volt power supply to 
ground and to the center tap of transformer primary 158. This capacitor 
provides ripple rejection. That is necessary because the high frequencies 
involved would otherwise cause the output signals from transistors 154 and 
156 to be reduced. 
The output from transformer secondary 162 is applied to the inputs of a 
full wave rectifier consisting of diodes 164, 166, 168, and 170. This 
rectifier converts the alternating 400 volt peak-to-peak signal appearing 
across reference points C and D to a plus 200 volt charging voltage for a 
capacitor C172 connected across the rectifier output terminals. 
Capacitor C172 is employed to store the charge needed to enable visual 
warning display 26 and to turn off switching regulator 132. Specifically, 
when capacitor C172 is charged to a voltage matching that at the output of 
a divider network consisting of resistors R174 and R176, the sequential 
output pulses are not longer available at pins 10 and 9 of switching 
regulator 132. The input voltage to the divider network is supplied from 
capacitor C172 and fed to input pin 1 of switching regulator 132. 
The circuitry just described provides a constant voltage for operating 
visual warning display 26, thereby controlling the brightness of the flash 
provided by that display when its xenon gas is ionized. This brightness 
control is deemed necessary because, in a typical vehicular application, 
the voltage appearing at input terminal 178 can vary widely--for example, 
between 9 and 15 volts (the actual output voltage depends upon the state 
of charge of the vehicle's battery, the resistance in the vehicle's 
wiring, and the operation of the vehicle's voltage regulator). Therefore, 
the brightness of the flash provided by the visual warning display 26 
could vary to an unacceptable extent unless the battery output was 
converted to a constant operating voltage. 
When capacitor C172 is charged to the level at which its voltage matches 
the output voltage from the divider network consisting of resistors R174 
and R176, the divider network output voltage will be higher than the 
output voltage of a divider network consisting of resistors R180 and R182 
(the input voltage for that divider network is a plus 5 volts supplied 
from pins 13 and 14 of switching regulator 132). This causes a plus 5 
volt, capacitor charging signal to appear at pin 3 of the switching 
regulator. That signal is routed through diode 184 and a capacitor C186 to 
ground. Diode 184 provides isolation between capacitor C186 and the 
switching regulator. 
A second, associated capacitor C188 is connected across output pins 3 and 2 
of switching regulator 132. Capacitor C188 reduces current surge when the 
signals at pins 10 and 9 of switching regulator 132 are made unavailable 
by application of the matching voltage described above. This is important 
as it reduces noise in the circuit. 
When capacitor C186 is charged, a plus 5 volts signal is routed through a 
chip-to-chip isolation resistor R189 to one input of a NAND gate 190. A 
second resistor R192 is connected to ground between capacitor C186 and 
isolation resistor R189. This resistor and capacitor C186 together 
constitute a timing circuit which supplies an operating pulse of adequate 
width to a timing circuit composed of the just-mentioned NAND gate 190 and 
a second NAND gate 194. The timing circuit including the two NAND gates is 
employed to turn visual warning display 26 on and off at a controlled, 
typically ten or one cycle per second rate. 
With the plus 5 volt signal applied to input 2 of NAND gate 190, a signal 
will appear across the output of that gate because pin 1 is also supplied 
with a positive signal at that point in the operation of circuit 27 as 
will become apparent hereinafter. 
With pins 1 and 2 of NAND gate 190 positive, a negative signal appears at 
output pin 3 of the gate. The negative signal is applied to pins 1 and 2 
of NAND gate 194, causing a positive signal to appear at its output pin 3. 
The positive signal appearing at pin 3 of NAND gate 194 is routed through a 
current limiting resistor R196 and a biasing resistor R198 to ground. The 
plus 5 volt signal is also routed to thyristor 200, turning the thyristor 
on. 
This discharges a capacitor C202 which has heretofore been charged through 
a charge resistor R204. Capacitor C202 is charged at the same time as the 
above-mentioned capacitor C172. 
Capacitor C202 discharges through a trigger transformer 206. That 
transformer steps up the capacitor discharge voltage to a level of 
sufficient magnitude to ionize the xenon gas in visual warning display 26. 
Typically, the step-up voltage will be in the range of 200 volts in to 
4000 volts out. 
Upon ionization, the xenon emits light at an intensity proportional to the 
capacitance of capacitor C172 multiplied by the voltage to which that 
capacitor is charged squared. 
While visual warning display 26 is turned on, switching regulator 132 is 
turned off so that it will not continue to supply the output signal 
employed to turn visual warning display 26 on. Switching regulator 132 is 
turned off by a circuit which includes a bilateral field effect transistor 
switch 208. Field effect transistor switch 208 is turned on by the 
positive signal appearing at output pin 3 of NAND gate 194. 
The turning on the field effect transistor switch 208 drops the output 
voltage from the divider network consisting of resistors R180 and R182 to 
ground. That blocks the theretofore available output signal from pin 2 of 
switching regulator 132. 
With no signal appearing at switching regulator pin 2, the output signal 
from the divider network consisting of resistors R176 and R174 goes to 
ground. Therefore, capacitor C202 cannot be recharged to retrigger visual 
warning display 26. 
It will be noted that an associated capacitor C210 is connected across the 
output pin 3 of NAND gate 194. This is a timing capacitor which regulates 
the rate at which visual warning display 26 is turned on and off. 
Capacitor C210 is charged during that part of the operating cycle of 
circuit 27 in which the input of NAND gate 194 is low and a positive 
signal therefore appears at its output pin 3. When capacitor C210 reaches 
a threshold charge, a negative signal appears at pin 1 of NAND gate 190. 
This is because, as capacitor C210 charges, the magnitude of the signal 
appearing at pin 1 of NAND gate 190 decreases towards a threshold value. 
At that point, the NAND gate switches to a logic low, causing a positive 
signal to appear at its output pin 3. This causes pins 1 and 2 of NAND 
gate 194 to go positive, a negative signal thereupon appearing at the 
output pin 3 of that gate. 
Capacitor C210 is connected to pin 1 of NAND gate 190 through a resistor 
R212 and a forward bias diode 214. Resistor R212 controls the charge rate 
of capacitor C210 during that part of the duty cycle in which a logic high 
or positive voltage appears at output pin 3 of NAND gate 194. This charge 
rate is so selected that visual warning display 26 will be turned on for a 
sufficient portion of each duty cycle to ionize the xenon gas and then 
extinguish the discharge. 
Forward bias diode 214 drops resistor R212 out of the capacitor charge 
controlling circuit when NAND gate 194 is switched to a logic low; i.e., 
when a negative voltage appears at pin 3 of that NAND gate. Diode 214 
thereby acts as a pulse width shaper, controlling the on time of NAND 
gates 190 and 194. 
With NAND gate 194 at a logic low, capacitor C210 is recharged through a 
circuit consisting of an adjustable resistor R216, a fixed resistor R218, 
a field effect transistor switch 220, and a field effect transistor switch 
222. Therefore the duty cycle just described can be repeated the next time 
a plus 5 volt enabling pulse appears at input pin 2 of NAND gate 190. 
The circuit consisting of resistors R216 and R218 and field effect 
transistor switches 220 and 222 controls the time for which NAND gate 194 
remains at a logic low and, as a consequence, the flash rate of visual 
warning display 26. 
When NAND gate 190 reverts to a logic high state and a plus voltage signal 
is routed to adjustable and fixed resistors R216 and R218, field effect 
transistor switches 220 and 222 are turned on. This allows capacitor C210 
to recharge to the level necessary to enable it to perform the function 
discussed when NAND gate 194 next reverts to a logic high due to the 
application of a plus 5 volt signal to its input pin 2. 
Variable resistor R216 is employed to adjust the charging rate of capacitor 
C210 and, therefore, the rate at which the visual warning display 26 can 
be turned on and off. 
A third resistor R224 is connected in series with resistors R216 and R218. 
This resistor decreases the on-off or flash rate of visual warning display 
26 when one or both of the field effect transistor switches 220 and 222 
are open while capacitor C210 is being charged. If this occurs, resistor 
R224 is connected in series with resistors R216 and R218 rather than being 
bypassed through switches 220 and 222. Consequently, capacitor C210 
charges more slowly. 
Field effect transistor switch 220 is turned off during the capacitor 
charging part of the duty cycle by a negative pulse appearing at pin 3 of 
NAND gate 226. This NAND gate is employed to decrease the rate of 
operation of visual warning display 26 after a specified period, typically 
30 seconds. The decrease in the flash rate conserves the battery of the 
vehicle in which emergency deceleration warning device 22 is employed. 
This may be desirable if the vehicle has triggered the detector for a 
longer than normal time--for example, if the vehicle has gone into a 
ditch. In such cases, it is desirable to continue the warning provided by 
display 26 for an extended period of time. 
The operation of NAND gate 226 is controlled by a R-C circuit which 
includes a resistor R228 and a capacitor C230. The input to this circuit 
is a plus 5 volts. 
When capacitor C230 is charged, plus voltages appear at pins 1 and 2 of 
NAND gate 226; and a logic low (minus voltage) appears at output pin 3. 
This output signal is routed to field effect transistor 220, turning off 
that switch and placing resistor R224 in the capacitor C210 charging 
circuit as discussed above. 
The charging of capacitor C230 is initiated when photoelectric detector 104 
produces an output signal indicative of abnormal braking and switching 
regulator 132 is thereby enabled. 
Field effect switch 222 is turned off to similarly increase the charging 
rate of capacitor C210 and produce a slower flash rate for so long as one 
or more of the four accessory inputs 138, 140, 142, and 144 is enabled. 
When this occurs, the typically plus 12 volt signal is applied to the base 
of a transistor 236 through: (1) the enabled input, for example the input 
144 coupled to circuit 27 through diode 143, and (2) a circuit including a 
current limiting resistor R232 and a biasing resistor R234. This pulls the 
collector of transistor 236 to ground through a timing circuit. 
That circuit is composed of a series-connected, current limiting resistor 
R238 and capacitor C240 and a parallel-connected, time constant-providing 
resistor R242. This timing circuit is operated by the plus 5 volt signal 
appearing at the input pins of switching regulator 132. 
With the circuit including the just described R-C network activated, 
capacitor C240 charges, keeping the collector of transistor 236 at ground. 
With the transistor collector at ground, a negative voltage is applied to 
field effect transistor 222. That transistor is accordingly turned off. 
This connects resistor R224 into the capacitor C210 charging circuit, 
reducing the capacitor charging rate and thereby decreasing the rate at 
which visual warning display 26 is turned on and off or flashed. 
Capacitor C240 will charge (or remain charged) for so long as one or more 
of the accessory inputs 138, 140, 142, and 144 is enabled. Consequently, 
the collector of transistor 236 will remain at or near ground; and field 
effect transistor switch will remain turned off, producing the wanted slow 
flash rate, until all enabling signals from the accessory inputs are 
removed and the resistor R242 and resistor R235 charge capacitor C240 to 
the threshold voltage. 
Once there is no input from 138, 140, 142 or 144, visual warning display 26 
will continue to be turned on and off for a minimum period of typically 
five seconds. The duration of this period is determined by a timing 
circuit which includes: (1) a capacitor C244; (2) an adjustable resistor 
R246 which allows the minimum duration to be adjusted; and (3) a fixed 
resistor R248 which sets the minimum time to which the period of operation 
of visual warning display 26 can be reduced. This circuit is connected 
between ground and the plus 5 volt signal appearing at the input pins to 
switching regulator 132. 
The operating circuitry for visual warning display 26 is turned off after 
the above-mentioned period of minimum duration by a circuit which includes 
a transistor 250 connected in parallel through a biasing resistor R252 and 
a current-limiting resistor R254 to the five circuit enabling inputs 114, 
138, 140, 142, and 144. A diode 256 between the four last-mentioned inputs 
and current limiting resistor R254 isolates input 114 from the four 
accessory inputs 138, 140, 142, and 144. Isolation is provided so that 
enabling input 114 will cause visual warning display 26 to flash rapidly 
whereas the other four inputs will instead cause visual warning display 26 
to be operated at the slower rate. 
With an input applied to the base of transistor 250, its collector goes 
low, applying logic low (minus voltage) signals to the input pins 1 and 2 
of NAND gate 258. That causes a logic high or plus voltage signal to 
appear at the output pin 3 of that NAND gate. The output signal is routed 
to transistor 122: (1) through a diode 260, which isolates NAND gate 258 
from the signals supplied from inputs 114, 138, 140, 142, and 144; and (2) 
then through current limiting resistor R120. This insures that transistors 
122 and 130 remain on and that the enabling plus 12 volt voltage is 
therefore applied to the input pins of switching regulator 132 for the 
minimum period determined by the timing circuit consisting of capacitor 
C244 and resistors R246 and R248. 
Once the minimum period runs, capacitor C244 charges; and the collector of 
transistor 250 goes logic high, as do the inputs 1 and 2 of NAND gate 258. 
A logic low therefore appears at NAND gate output 3. This drops the NAND 
gate out of the circuit controlling the operation of switching regulator 
132, resetting or initializing circuit 27. 
The circuitry shown in FIG. 12 comprises FIGS. 12A and 12B also includes a 
second timing circuit. This circuit insures that switching regulator 132 
will remain on for a period of minimum duration (typically 5 seconds) once 
the switching regulator is enabled. This is necessary because a thermal 
protection circuit, described hereinafter, might otherwise earlier 
disenable switching regulator 132--for example, if the ambient temperature 
is very high. In that case, a warning of adequate duration might not be 
given. 
The timing circuit in question includes a capacitor C262 and a resistor 
R264. Resistor R264 also cooperates with a resistor R266 to form a divider 
network. That network sets a reference voltage from the plus 5 volt supply 
to input pin 16 of switching regulator 132. 
The just-mentioned thermal protection circuit protects switching regulator 
132 and heat sensitive transistors 154 and 156 from overheating. It 
includes: (1) the above-mentioned timing circuit consisting of a capacitor 
C262 and resistor R264, (2) resistor R266, (3) resistor R268, and (4) a 
diode 270. 
The diode 270 is disposed in intimate heat transfer relationship to heat 
sensitive transistors 154 and 156. Therefore, when the transistor 
temperature increases to a level above a threshold value, the P-N junction 
of the diode collapses; the voltage across the diode decreases; and the 
input voltage at pin 15 of switching regulator 132 becomes lower than the 
voltage at pin 16. This turns the switching regulator off until such time 
as the temperature of transistors 154 and 156 decreases to the threshold 
level. At this point, the voltage at input pin 15 again become higher than 
the voltage at pin 16; and switching regulator 132 is again enabled. 
Because of the rapid dissipation of heat, the switching regulator will be 
off only momentarily; and emergency deceleration warning device will 
consequently remain out of operation for only a few seconds at most. 
Yet another novel feature of the novel emergency deceleration warning 
device 22 described herein is a circuit which shuts off visual warning 
display 26 when the power supply voltage drops below a selected, minimum 
level. In a vehicular application of our invention, this results in the 
device being turned off while there is still enough energy in the 
vehicle's storage battery to restart the vehicle. 
The circuit just described includes a transistor 272 connected to the plus 
12 volt power supply through a voltage divider consisting of resistors 
R274 and R276 and employed to supply the appropriate threshold voltage to 
the transistor. This turns transistor 272 on. 
With the transistor conducting, its collector is low; and a field effect 
transistor switch 278 wired to that collector is turned off. This enables 
switching regulator 132. 
As the voltage applied to the base of transistor 272 through the divider 
network consisting of resistors R274 and R276 drops below the threshold 
level, the collector of transistor 272 is raised to a plus 5 volt 
potential by a R-C circuit consisting of a resistor R280 and a capacitor 
C282. This turns on field effect transistor switch 278. That brings the 
potential on output pin 2 of switch regulator 132 to zero, disenabling the 
switching regulator. 
The R-C or timing circuit composed of resistor R280 and capacitor C282 is 
provided so that the switching regulator can be enabled and visual warning 
display 26 turned on and off for a minimum period (typically five seconds) 
even though the battery voltage may drop below the threshold value during 
that period. 
A capacitor C284 is connected to ground and the plus 5 volt power source 
repeatedly referred to above. This is a bypass capacitor again provided 
for ripple rejection. 
Also, a capacitor C286 and a resistor R288 are connected between input pins 
5 and 6 of switching regulator 132 and ground. The capacitor and resistor 
together constitute an R-C circuit which controls the frequency at which 
switching regulator 132 operates. Typically, the switching regulator will 
be operated at a frequency in the range of 40-45 kHz. 
Also, two resistors R290 and R292 are connected to input pin 4, ground, and 
the plus 5 volt supply. These resistors are used to limit the maximum 
pulse signal from output pins 10 and 9 and, in so doing, to limit the 
maximum current surge from the vehicle battery. 
The final component of the emergency deceleration warning device 22 
illustrated in FIG. 12 is the above-discussed incandescent lamp 30 which 
is turned on and off in unison with vehicle 20's lower mounted stop lights 
46 and 48. One terminal of lamp 30 is connected to ground. The other 
terminal 290 is connected to the operating system of brake lights 46 and 
48 directly or through a control module (not shown) which is typically 
provided to coordinate the operation of the brake and turn signals of a 
modern automobile. 
The decelerometers we employ in emergency deceleration warning device 22 
may take many different forms. One appropriate decelerometer was described 
above in conjunction with FIGS. 4-6 of the drawing. A second preferred 
form of decelerometer is illustrated in FIGS. 7 and 8 and identified by 
reference character 350. 
That decelerometer includes an elongated member 352 in which a track 354 is 
formed. 
A rolling opaque element 356, typically a thin cylinder, is trapped in 
track 354 by transparent covers 358 and 360 fixed to opposite sides of the 
member 352 in which track 354 is formed. 
The assembly of track and rolling element is pivotably fixed as by a pin 
360 to the upper end of a bracket 362. At its lower end, bracket 362 is 
fixed in any convenient fashion to the casing 32 of warning unit 22. 
With decelerometer component 352 inclined at a typical, 26.degree. angle 
from the horizontal shown in FIG. 7, rolling element 356 rests in the 
bottom end 365 of track 354. When the vehicle (hereinafter referred to as 
vehicle 20) equipped with an emergency deceleration warning device as 
depicted in FIGS. 2 and 3 but employing decelerometer 350 decelerates, 
rolling element 356 moves up track 354. The point to which it travels is 
determined by the rate of deceleration. 
If that deceleration is sufficiently rapid to pose a clear and present 
danger, element 356 will travel up track 354 far enough to allow a beam of 
energy to pass from an infrared, photoelectric, or other emitter 366 
through track 354 and impinge upon an associated detector 368 (the emitter 
and detector may be incorporated in a single unit such as that identified 
by reference character 78 in FIG. 5). This causes detector 368 to emit an 
electrical signal which enables circuit 27. Again, that circuit causes 
gas-filled discharge lamp 26 to be turned on and off at a rapid rate, 
signaling following vehicles that an emergency exists. 
Once the deceleration of vehicle 20 falls below the level posing a danger, 
element 356 will retreat toward the lower end 365 of track 354. There, it 
interrupts the beam of radiation from emitter 366. Thereafter, flasher 26 
will be turned off, provided that the minimum period of operation 
controlled by circuit 27 has expired. 
Like the decelerometer 24 discussed above, decelerometer 350 can be 
adjusted to compensate for the surface over which vehicle 20 is traveling. 
This allows the deceleration of vehicle 20 required for activation of 
visual warning display 26 to be decreased as the coefficient of friction 
between that surface and the tires 370 of vehicle 20 decreases, for 
example. 
In particular, a retainer 372 incorporated in decelerometer 350 engages a 
pointer 374 at the end of decelerometer member 352. That frictionally 
retains member 352 in the angular position to which it is adjusted. A 
scale, again reading in G force or road condition, and not shown in the 
drawings, can be added to retaining member 372 to facilitate the 
adjustment of decelerometer 350 to changing road conditions. 
The advantage of the decelerometer 350 just described is that it is less 
apt to enable circuit 27 if a shock is transmitted to it by virtue of 
vehicle 20 hitting a bump or a chuckhole, for example. The imposition upon 
rolling element 356 of a force resulting from that type of incident merely 
tends to move the element vertically as suggested by arrow 376 in FIG. 7. 
However, because element 356 is kept from moving in that direction by the 
upper side 378 of track 354, it cannot uncover the optical path between 
emitter 366 and detector 368. Therefore, visual warning display 26 is not 
falsely triggered merely by vehicle 20 passing over a bump or hitting a 
chuckhole. 
A third, exemplary decelerometer 380 which can be employed in the emergency 
deceleration warning device 22 of FIGS. 2 and 3 is illustrated in FIGS. 9 
and 10. That decelerometer also includes a pendulum--in this case 
identified by reference character 382. Pendulum 382 is pivotably supported 
from the side wall 36 of warning device casing 32 as by a pivot pin 384 
and a tubular spacer 386. 
Absent deceleration of vehicle 20, pendulum 382 hangs from pivot pin 384 in 
the position or orientation shown in FIG. 9. As vehicle 20 decelerates, 
pendulum 382 swings about pivot member 384 in the clockwise direction 
indicated by arrow 394 in FIG. 9. The magnitude of the pendulum swing is 
proportional to the magnitude of deceleration of vehicle 20. 
A stop 390 extends through an arcuate track 392 in the pendulum. The stop 
is fixed to warning device casing side wall 36 by fastener 394. This stop 
limits the travel of pendulum 382, keeping the pendulum from hitting other 
components of decelerometer 380. 
The arc through which pendulum 382 swings is identified by a system which 
includes: (1) three emitter/detector units 396, 398, and 400; (2) a solid 
state decoder 402 such as a 4051BCP; and (3) reflective patches 403, 404, 
406, and 408 on pendulum 382. This system of reflective patches is 
designed so that a unique combination of the three emitter/detector units 
396, 398, and 400 shown in the following table will lie opposite a 
different reflective patch for each of the eight deceleration rates 
ranging from zero to seven-eighths G over which decelerometer 380 is 
designed to operate. 
______________________________________ 
ACTIVE 
DECELERATION (G) 
EMITTER/DETECTOR UNIT(S) 
______________________________________ 
0 396, 398, 400 
1/8 396, 398 
1/4 396, 400 
3/8 396 
1/2 398, 400 
5/8 398 
3/4 400 
7/8 None 
______________________________________ 
When it is located opposite a reflective patch, the detector (not 
separately shown) in each of the units 396, 398, and 400 will become 
active by virtue of light from the emitter of the unit (typically, a LED) 
being reflected back on to its detector. With light being reflected back 
upon it, the detector element of each unit 396, 398, and 400 will generate 
an electrical output signal. 
The signals from the three detectors are applied to, respectively, input 
pins C, B, and A of decoder 402. Depending upon the particular combination 
of units 396, 398 and 400 that is active, the decoder will generate at one 
of its outputs 1 through 8 a signal indicative of the rate of deceleration 
of vehicle 20 as detected by pendulum 382. 
Conventional, manually operated switches 410 . . . 424 are employed to 
connect a selected one of the decoder outputs 1 through 8 to visual 
warning display operating circuit 27. Depending upon the output that is 
selected, circuit 27 will be enabled and visual warning display 26 flashed 
on and off whenever the rate of deceleration represented by the selected 
output is reached. Alternatively, appropriate sensors (not shown) can be 
incorporated in emergency deceleration warning device 22 to ascertain road 
conditions and automatically connect the appropriate one of the decoder 
outputs 1 through 8 to circuit 27. 
The invention may be embodied in specific forms in addition to those 
discussed above without departing from the spirit or essential 
characteristics thereof. The present embodiments are therefore to be 
considered in all respects as illustrative and not restrictive, the scope 
of the invention being indicated by the appended claims rather than by the 
foregoing description. All changes which come within the meaning and range 
of equivalency of the claims are therefore intended to be embraced 
therein.