Diving helmet

A diving helmet comprises a transparent front window and an air supply chamber at the back. The air supplied from a ship on the water is fed into the helmet through the air supply chamber. The air in the air supply chamber is partially fed to diver's mouth through an air hole formed in the wall of the helmet, thereby preventing the front window from getting misted. The air supply chamber is made as a box separately from the helmet and is embedded therein.

BACKGROUND OF THE INVENTION 
This invention relates to a diving helmet. 
A known diving helmet comprises a head and a body contacting portion which 
are made of a heavy metal or synthetic resin with a relatively large 
thickness to act as diving weight. It comprises a transparent front 
window, and an air supply tube is connected to the back of the head. 
When air is supplied into the helmet, air exhaust noise generates and 
vibrates in the small space of the helmet to place a diver in 
uncomfortable condition. 
If an air inlet is formed at the back remote from diver's mouth, he will be 
worried about leakage of fresh air before breathing, if he is a beginner. 
Further it is necessary to supply fresh low-humidity air to the front 
window enough to take off mist formed by breathing. 
According to the present invention, the above disadvantages will be solved. 
According to the present invention, there is provided a diving helmet which 
comprises a head and a body-contacting portion made of regid material with 
relatively large thickness to act as weight, the head comprising a 
transparent front window, an air supply chamber connected with an air 
supply tube at the back of the helmet, and a plurality of air holes which 
allow the air supply chamber to communicate with the inside of the helmet, 
at least one of the air holes being extended close to the front window. 
The air supplied into the helmet through the air supply tube is 
depressurized in the air supply chamber, from which it is fed into the 
helmet through the air holes. Thus, the exhaust velocity through the air 
holes becomes lower than that directly from the air supply tube, thereby 
turning down exhaust noise. The fresh air through the air hole is 
partially blown to the front window directly, thereby preventing the 
window from getting misted.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION 
FIG. 1 illustrates one embodiment of the present invention. Numeral 1 
denotes a diving helmet in which there is provided a relatively thick, 
heavy body contacting portion 6 which comprises a head 2, right and left 
shoulder contacting portions 3, a breast-contacting portion 4 and a 
neck-contacting portion 5 so that the helmet 1 itself may act as weight. 
The helmet 1 comprises a front transparent window 7. 
An air supply tube 8 is connected to the neck contacting portion 5 at the 
back of the head 2 of the helmet 1. Air is fed from a ship on the water 
through the air supply tube so that the helmet 1 may be always filled with 
fresh air. The helmet 1 is used for underwater walking or sightseeing at 
relatively small, below 10 m, depth. 
At the neck-contacting portion 5 of the lower back portion of the helmet 1, 
there are provided an air supply chamber 9 which communicates with the air 
supply tube 8, and an air exhaust chamber 10. The air exhaust chamber 10 
has width enough to extend right and left shoulder-contacting portions 3. 
The front wall 10a of the air exhaust chamber 10 has a plurality of air 
exhaust guide holes 11 horizontally, while the rear wall 10b thereof has a 
plurality of air exhaust holes 12. The air exhaust holes 12 have 
relatively small diameters, thereby allowing exhausted bubbles to be 
smaller and keeping exhaust velocity constant. The front wall 9a of the 
air supply chamber 9 has a plurality of openings 14. 
There are provided a pair of air holes 15 and 15 from the right and left 
side walls 9b and 9b of the air supply chamber 9 to diver's mouth just 
before the front window 7 through the thick wall of the 
shoulder-contacting portions 3 and 3. In this embodiment, there are 
provided a pair of air holes 15 and 15, but one hole 15 may be provided. 
It is not so easy to form the air supply chamber 9 integrally with the air 
exhaust chamber 10, the shoulder-contacting portion 3 and the 
neck-contacting portion 5 therebelow. 
Thus, as shown in FIG. 2, the air supply chamber 9 may be formed separately 
from the helmet body. An air supply chamber 9 is formed in a box 16, the 
back wall 16a of which is connected with a tube 17. A plurality of 
openings 18 which communicate with the inside of the helmet 1 are provided 
in the front wall of the box 16. A certain length of air tube 19 is 
connected with the side wall 16c of the box 16. The box 16 is embedded in 
the thick neck-contacting portion 5 at the back of the helmet 1 so that 
the outer end 17a of the tube 17 may project outwardly and the end 19a of 
the air tube 19 may be positioned just before the window 19. Therefore, 
the air supply chamber 9 and the air holes can be easily formed. 
The advantages of the invention are as follows: 
(a) The air fed through the air supply tube 8 is depressurized in the air 
supply chamber 9 and is supplied into the helmet 1, thereby turning down 
air supply noise in the helmet. 
(b) Fresh air is blown directly through at least one of the air holes to 
diver's mouth, thereby keeping him reliable if he is a beginner. 
(c) The air fed through the air hole is partially blown to the window, 
thereby preventing the window from getting misted. 
The above description merely relates to a preferred embodiment of the 
present invention, and various changes and modifications are possible 
without departing from claims as follows.