Headrest apparatus

A headrest apparatus comprising at least one support member mounted on a seat, a high cushioning elastic base provided on said support member, a low cushioning elastic support wall provided on said elastic base, an empty room formed in front of said elastic support wall, a head resting part formed at the front side of this empty room and a gel material layer formed by filling said empty room with gel material, wherein a load to be applied to said head resting part is applied to said gel material layer.

BACKGROUND OF THE INVENTION 
The present invention relates to the headrest apparatus for use in seats of 
automobiles, airplanes, etc. 
This type of conventional apparatus has a head resting part which supports 
a head of a man and comprises an elastic layer such as, for example, a 
molded part made of foamed polyurethane inside which a supporting member 
such as the support member is embedded. 
Such headrest apparatus as described above is disclosed, for example, in 
the Japanese Patent Gazette (laying-open) No. SHO. 56-89213. 
In such headrest apparatus as described above, there is a problem that a 
repulsive force of the elastic layer deteriorates the shock absorbing 
effect of said elastic layer as a whole since, when a sudden and strong 
shock is added to the head as in case of rear end collision, the head 
sinks into the elastic layer once and is pushed out toward the front by 
the repulsive force of this elastic layer because the head of the man is 
received by the elastic layer. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a headrest apparatus which 
absorbs a sudden shock the human head receives without causing strong 
repulsion. 
In the apparatus in accordance with the present invention, a head resting 
part is filled with gel material, an elastic support wall with small 
cushion effect is formed behind said head resting part, and a base part 
with large cushion effect is arranged behind this elastic support wall and 
a shock is reduced and absorbed by the above triple construction. 
In case of the apparatus in accordance with the present invention, a shock 
to be applied to the head is absorbed by non-elastic deformation of the 
gel material layer, dispersed by elastic deformation of the low cushioning 
elastic support wall and reduced by large and flexible elastic deformation 
of the high cushioning base part which supports the elastic support wall 
whereby the recovering repulsive force of said base part and the elastic 
support wall will reach the head while being absorbed by non-elastic 
deformation of the gel material layer and the repulsive elastic force 
received by the head can therefore be reduced.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The headrest apparatus in accordance with the present invention has support 
mechanism 10 and pillow member 20 fitted to this support mechanism 10, 
which comprises a pair of support members 11 and 11' made of a hard 
material such as metal and pillow member securing part 12 provided between 
support members 11 and 11' which are fixed to seat 30 to be adjustable in 
its height. 
Therefore, seat 30 is provided with base 13 and support members 11 and 11' 
are inserted into base 13 to be freely movable in the vertical direction 
and engaged and fixed at a desired height. 
Said pillow member 20 can be provided, as required, to be pivotable between 
said support members 11 and 11' and thus inclined to an appropriate angle 
for the human head. In other words, the angle of said pillow member 20 to 
the support members 11 and 11' can be varied in accordance with the 
position of the human head. 
Such construction as described above has been well known in conventional 
headrest apparatuses. 
Said pillow member 20 comprises high cushioning elastic base part 21, which 
is made up so that said pillow member securing part 12 is sunk into it 
such as, for example, a block member made of foamed polyurethane or foamed 
polyethylene which is foamed by 60 times and molded, low cushioning 
elastic support wall 22 which is multi-layered at the front surface of 
said base part 21 such as, for example, a layer made of said foamed resin 
which is foamed by approximately 30 times and molded, head resting part 23 
formed in front of said elastic support wall 22 by extending a soft cloth 
such as, for example, a sheet material made of polyurethane, and gel 
material layer 24 made up by filling an empty room formed between said 
elastic support wall 22 and said head resting part 23 with gel material. 
Though the thickness of said elastic base part 21 can be determined as 
desired, it is generally approximately 30 to 50 mm and the thickness of 
said elastic support wall 22 is approximately 3 to 7 mm in case the 
thickness of elastic base part 21 is 30 to 50 mm. 
On the other hand, the thickness of said gel material layer 24 is generally 
approximately 5mm but it can be 10 to 20mm depending on the case. 
The thickness of every part can be freely determined and is not limited to 
the values shown above. 
Though the sheet which forms head resting part 23 is adapted to integrally 
cover base part 21 in this embodiment, the external covering layer of head 
resting part 23 can be separated from base part 21. 
The gel material which forms said gel material layer 24 is preferable to 
provide the penetration value of 50 to 200, particularly 100 to 200 and, 
if the penetration value is excessively small, the shock absorbing 
capacity will deteriorate and, if the penetration value is excessively 
large, a repulsive force applied to the head will be a problem. 
The penetration value herein shown is measured according to JIS K 2530-1976 
(50 g load) which is one of Japanese Industrial Standards. 
This standard relates to the petroleum asphalt penetration testing method. 
The test has been conducted with a load of 100 g for a test sample with 
the penetration value of 350 or less but the load of 50 g has been used 
in the test for gelled material. 
Since the apparatus in accordance with the present invention is as 
described above, the head of a man, when shocked by rear-end collision of 
the car, deforms low cushioning elastic support wall 22 while suddenly 
deforming gel material layer 24, and simultaneously sinks into base part 
21 due to deformation of this elastic support wall 22. At this time, said 
gel material layer 24 deforms elastic support wall 22 while absorbing the 
shock energy from the human head by its non-elastic deformation and 
accordingly, the repulsive force due to repulsion at the instant of a 
shock applied to the human head can be small. 
Shock energy due to deformation of elastic support wall 22 is transmitted 
to in a wide range since this elastic support wall 22 has a low cushioning 
effect and therefore shock energy is widely dispersed and transmitted to 
base part 21. 
After base part 21 and elastic support wall 22 have been deformed by said 
shock energy and have absorbed the shock energy, the recovering repulsive 
force of base part 21 and elastic support wall 22 act as a repulsive force 
on the human head and push out the head frontwardly. In this case, the 
deformation of gel material layer 24 is non-elastic deformation and 
therefore a repulsive elastic force to the human head can be reduced. 
Accordingly, an instantaneous force arising from an elastic force applied 
to the human head is effectively attenuated by deformation of gel material 
layer 24. 
Hereupon, the apparatus in accordance with the present invention can be 
made up by combining elastic base part 41 and elastic support wall 42 of 
pillow member 40 which are separately made and the empty room formed 
between said elastic support wall 42 and head resting part 43 can be 
formed in the shape of boat as shown in FIG. 4. In this case, after gel 
material layer 45 has been formed by filling the boat-shaped empty room 
with gel material, head receiving member 46 can be formed by sealing the 
empty room with elastic layer 44 such as, for example, foamed polyurethane 
sheet and fitted to base part 41. 
If head receiving member 46 is separately made as described above, elastic 
layer 44 of head receiving member 46 can be made to form head resting part 
43 but generally the front surface part of the external covering layer 
which integrally covers head receiving member 46 and base part 41 is used 
as head resting part 43. 
In addition, said gel material layers 24 and 45 can preferably made up with 
silicone gel and Toray Silicone CY52 (trademark)(manufactured by Toray 
Silicone Kabushiki Kaisha) is suitable as such material. 
If silicone is thus used as the material, the weight and price of silicone 
can be reduced by mixing fine hollow spherical particles such as fine 
particles of 5 to 300.mu. in diamater referred to as micro sphere, micro 
balloon, hollow bubble or synthetic foam in silicone. 
A compound type silicone gel material mixed with fine hollow particles as 
described above is described in detail in the Specification of U.S. patent 
application Ser. No. 814,726. 
Said gel material layers 24 and 25 in said embodiment are formed, as a 
whole, as a single layer but these gel material layers can be formed with 
a plurality of block members such as, for example, gel material balls 50 
as shown in FIG. 5 or cylindrical members 60 made of gel material as shown 
in FIG. 6. In this case, since the empty room between elastic support 
walls 22 and 24 and head resting parts 23 and 43 is filled with a 
plurality of balls 50 or cylindrical members 60, spaces among balls 50 or 
cylindrical members 60 act as air cushion. 
For the block members such as balls 50 or cylindrical members 60, it is 
preferable to cover the internal gel material with external covering layer 
51 or 61. A thin film made of elastic material such as silicone rubber can 
be used as this external covering layer 51 or 61 or a hardened film can be 
produced on the surface of silicone gel by chemical reaction. 
Silicone gel on which the hardened film is formed is disclosed in the 
Japanese Patent Gazette No. SHO. 59-30932. 
said embodiments allow addition of a number of modifications without any 
deviation from the intent of the present invention and the present 
invention is not limited to said embodiments and allows various 
modifications.