Teeth-held head tilt alarm

An alarm intended to alert the operator of dangerous equipment, such as the driver of an automobile, when his head tilts as from drowsiness or sleep. Intended to be of utmost convenience so as to encourage its use, the device is gripped between the teeth by a mouthpiece. Vibration concomitant with making the sound it emits is partially transmitted through the bone structure of the head, reducing the needed noise level and so the disturbance of nearby persons. The preferred embodiment is sensitive to tilt in any direction, and may be stored inverted in which position it tolerates large tip angles without sounding.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
Automobile drivers and operators of other dangerous equipment occasionally 
continue operation past the time when they should stop--when they are 
sleepy. This device is an alarm system to emit a wakening signal should 
the operator's head tilt. It is intended to improve the chances of 
equipment operators, and nearby persons, surviving an episode of sleep; 
thus is considered safety equipment of a specialized kind. 
2. Description of Prior Art 
A variety of devices for the purpose of awakening vehicle drivers has been 
proposed. The need has increased in recent years because long stretches of 
boring freeway have become more common, as has the use of trucks on long 
hauls. The use of tilting of the head to actuate the wakening alarm is 
customary, because the need to make the device easily attached and 
adjusted has been recognized in the art. 
Except for Philians U.S. Pat. No. 3,054,868 which uses a chin plate switch 
attached to the clothing, the present art uses devices attached to a hat, 
to eyeglass bows, or more commonly to the ear. My use of the teeth to grip 
the device overcomes two problems which may have prevented widespread use 
of this type of device. First, the present invention is obviously easier 
and quicker to mount, which is an advantage in a dark car, while watching 
the road with the eyes and steering the car with one hand. Second, in 
using direct coupling to the bone structure it becomes possible to lower 
the necessary level of audible sounds, rendering the device less 
disturbing to other occupants of the vehicle. This is possible because the 
wearer receives some of the sensation of sound from vibration of the 
mouthpiece transmitted through the bone structure to his ear. 
Most of the prior art relies on forward tilt of the head in one plane to 
close a normally-open mercury switch. Morrison U.S. Pat. No. 2,713,159 and 
Greene U.S. Pat. No. 3,076,186 include switches which will close if tilted 
in any plane, but no showing of operability for these switches was made. 
The present invention responds to tilt in any direction, and also reduces 
the cost of the switch by making it of fewer parts. The switch includes 
specific features developed by test to improve operation--specifically to 
reduce hysteresis. 
In addition to making a head-tilt alarm easy to install, one should 
recognize the fact that the use of it will probably be very irregular, 
interrupted by months or years when it is simply kept inert, handy to the 
operator's seat. Thus operators are likely to forget how to activate and 
how to adjust the devices common in the prior art which have on-off 
switches or movable protrusions for adjusting the tilt angle setting at 
which the device actuates. The construction of my mercury switch has the 
advantage that merely turning the device upside down (inverting it) allows 
it to be stored for long periods with no drain on the battery. As the user 
erects it, the buzzer functions to confirm the battery is working, then 
stops when the silent zone is reached. The absence of a need to remember 
(or to re-learn by trial and error) how to use the device is an advantage 
over much of the prior art. The real object of this invention is to help 
save the lives of people who should not be driving, and minimizing the 
effect of their inebriation, confusion, or weariness could make an 
important contribution to that end. 
SUMMARY OF THE INVENTION 
The invention has a mouthpiece which is held between the upper and lower 
teeth as is a pipe. A portion of the mouthpiece extends outward between 
the lips. To this portion is attached a source of electric energy such as 
a battery, connected in series with a tilt switch and an electromagnetic 
buzzer. Such buzzers make audible sound by mechanical means, generating 
both a noise and a vibration. Both are transmitted to the ear and are 
perceived as a sound. 
The tilt switch is typically formed from two dished discs of thin metal, 
rim to rim, separated by an insulating washer. When the switch is upright, 
with the rims horizontal, a pool of mercury rests in the center of the 
lower disc which is only slightly dished. The upper disc is deeply dished 
in the preferred embodiment, enough to clear the top of the pool of 
mercury by a substantial distance. When the switch oriented as described 
is tilted sufficiently from the level or horizontal position, the mercury 
pool approaches the rims of the discs and establishes electrical contact 
from the lower disc through the mercury to the upper disc, closing the 
switch. When the tilt switch is inverted, the mercury pool rests in the 
(now lower) deeply dished disc and is isolated from the rim except at very 
large tilt angles. Thus it may be stored ready for use without 
depletingthe battery. The preferred embodiment thus omits the on-off 
switch as a simplification for the user. It also eliminates the adjustment 
of tilt angle so as to make it unnecessary for the user to be familiar 
with the device; the mouthpiece may have a contoured portion which allows 
the user to adjust the set angle a few degrees by "pointing" the device 
more toward the front or more toward the side of the head, and by gripping 
it close to or farther from the end of the mouthpiece. 
The principal novelty of this invention is that it is gripped in the teeth. 
Two distinct advantages derive from this. First, it is extremely easy to 
install on or to remove from the head, which may encourage more people to 
own it and to use it. Second, the force transmitted to the air to make 
sound is reacted directly by the head bones without intervening tissue, so 
the noise perceived through the bone structure is close to the maximum 
possible.

DETAILED DESCRIPTION OF THE INVENTION 
In FIG. 1 a partial cutaway view of the invention is shown in the mouth of 
a user. The invention may be retrieved from its storage place, inverted 
and placed in between the teeth quickly--a positive factor encouraging its 
use. Mouthpiece (1) is clamped between the upper and lower teeth, extends 
outward forward of the lips, and incorporates provision for holding all of 
the other elements except possibly the d.c. power source and the leads 
thereto. The angle at which the alarm is held is essentially level, 
although contoured portion (10) of mouthpiece (1) may be used to provide a 
few degrees adjustment. This is better illustrated in FIG. 7. When 
upright, the alarm sounds until it is within a few degrees of level so the 
user has no difficulty in finding the silent zone. FIG. 1 also shows the 
preferred placement of (2) tilt switch, (3) electromagnetic buzzer, (14) 
battery, and one connection (4) to the battery. All are placed relatively 
near the teeth so as to reduce the moment on the teeth, and the upper face 
of buzzer (3) provides a stable base when the invention is stored 
inverted. 
FIG. 2 shows mouthpiece (1) with contoured portion (10) in a side elevation 
of the preferred embodiment. Battery (14) is held between connections (4); 
in this embodiment one connection (4) is the lower surface of tilt switch 
(2). The other connection (4) carries voltage through lead (15) to buzzer 
(3). The other lead or leadwire from the buzzer is connected to spring 
(17) which makes electrical contact with the upper surface of tilt switch 
(2). 
In the embodiment shown in FIG. 2 tilt switch (2) is partially cut away to 
show first terminal (5), mercury pool (13), insulating gasket (8), and 
second terminal (6). The word terminal in this explanation is considered 
to include all matter to which current coming to or leaving the switch can 
flow with little or no resistance, except the pool of mercury which is 
separately identified. Thus electric potential is equal throughout a 
terminal, thus two metal parts in electric contact are one terminal, and a 
terminal may be a metallic or otherwise conductive coating independent of 
its supporting substrate. Also the expression transversely fixed means 
that the parts referred to may not shift relative to each other laterally, 
the features of elements remain in the position described relative to each 
other during tilt or inversion. "Abutting", "wall slope" and 
"Circumferential direction" have the obvious meanings. 
FIG. 3 is a top view of the alarm parts beneath the buzzer (3). The central 
part of spring (17) is cut away exposing switch (2) which is also 
partially cut away to show pool of mercury (13) as it would appear when 
the switch was tilted and mercury (13) was in contact with second terminal 
(6) as well as first terminal (5) on which it rests. Two leads (15) from 
the buzzer are shown, one attached to spring (17) and one to connection 
(4). As shown gasket (8) which separates terminals (5) and (6) is larger 
in diameter than either thus preventing them from touching connection (4), 
but obviously other means to isolate connection (4) are possible. 
FIG. 4 shows another version of tilt switch (2) in perspective, cut away to 
show the detail of first terminal (5), namely the concave (or depressed) 
portion (or region) (9) and rim portion (also called rim or first terminal 
rim) (11). This is the preferred embodiment; function of the switch would 
not be changed if the first terminal rim (11) were a separate part, or a 
non-conductor, or at a different elevation than that shown. A cover dish 
(16) is shown in FIG. 4. It serves to seal in the mercury and to support 
it when the switch is inverted, in the event the second terminal (6) takes 
the form of a ring or another shape with an internal opening or aperture 
in it which surrounds the pool of mercury at a point below the top of the 
pool. The aperture need not have cylindrical walls; my tests have shown 
that sharp ridges running in any direction help cause the mercury to break 
away at tilt angles close to those at which it makes contact thus reducing 
hysteresis. 
Irregularities in the internal surface of second terminal (6) are 
illustrated in the cross section view of a third version of tilt switch 
(2), FIG. 5. This view also shows concave portions (9) and (12) 
respectively on each terminal (5) and (6), as well as first terminal rim 
(11). The pool of mercury is not shown, but the ridges visible on terminal 
(6) are at a level approximately mid-height of the mercury pool for best 
results. 
FIG. 6 shows a fourth version of tilt switch (2) which would be suitable if 
the alarm was to be invertable not to store it but to provide for more 
than one tilt angle setting in a single alarm. A third terminal (7) is 
illustrated, and the second terminal (6) is illustrated as having a tab 
for making connections to it at one side of the saw-cut cross section. The 
same remarks as made earlier about the rim (11) and concave portion (9) of 
first terminal (5) apply to third terminal (7). 
FIG. 7 shows the preferred embodiment of the part of mouthpiece (1) 
containing contoured region (10). Many shapes are possible, but shown is 
two crowned ridges on the upper surface near the edges of the mouthpiece, 
the peak of the rightmost crowned region being closer to the end of the 
mouthpiece that the peak of the left ridge. Thus the wearer's teeth, which 
contact both upper and lower surfaces at an angle to the length of the 
mouthpiece will bear fairly securely on the broad lower surface and at two 
discrete areas on the upper surface (on the crowned ridges). By selecting 
the different amounts of penetration inward of the teeth or by moving the 
mouthpiece more to the front or more to the side of the head, the wearer 
can control the angle of the mouthpiece relative to horizontal or level, 
and so exert some control on the angle at which the tilt switch closes, 
sounding the alarm. 
This invention having been described in its preferred embodiment, it is 
clear that it is susceptible to numerous modifications and embodiments 
within the ability of those skilled in the art without the exercise of the 
inventive faculty. Accordingly, the scope of this invention is defined by 
the scope of the following claims.