Apparel – Guard or protector – For wearer's head
Patent
1996-07-02
1998-03-03
Neas, Michael A.
Apparel
Guard or protector
For wearer's head
2424, A42B 318
Patent
active
057220913
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to head equipment for pilots of military aircraft (airplanes and helicopters), the head equipment being of the type optionally including a face mask for breathing and comprising a helmet having a shell and a visor for placing in front of the eyes, which visor is generally movable relative to the shell by tilting about an axis which is either orthogonal to the midplane of the helmet or parallel to said plane, the visor tilting between a position in which it protects the eyes and the face and a position in which it disengages the eyes.
The visor must protect the face and the eyes, particularly in the event of ejection. When the helmet is provided with a headup visor, the helmet projects symbols onto the visor, which symbols become superposed on the environment.
In recent years, military aircraft pilots have had to face the threat of laser weapons which deliver a substantially monochromatic light beam of very high power.
Proposals have already been made to protect the retina of a pilot against this danger by coating the visor in thin layers constituting an interference filter which is opaque for the known operating wavelengths of high power pulse lasers. However, the opaque waveband and the density of the protection provided by an interference filter varies strongly as a function of the angle of incidence of the light beam on the filter. Protection that is satisfactory so long as the beam is coming straight at the visor, falls off quickly because of the change of angle of incidence when the beam is oblique.
SUMMARY OF THE INVENTION
The invention seeks to provide head equipment which is better at satisfying practical requirements of providing protection against laser attack than are previously proposed equipments; more particularly, it seeks to limit the angles of incidence at which it is possible for rays to reach the retina, and to do this without significantly reducing the solid angle of vision of the wearer of the equipment.
To achieve this result, the visor is given a shape such that when the visor is in position in front of the face and the eyes, the angles of incidence of rays that are capable of reaching the retina via the pupil are smaller than 15.degree., with this applying to both eyes, which angle of 15.degree. corresponds more or less to the limit beyond which protection falls off. In practice, it suffices if this result is achieved for beams reaching the eye in a cone having an angle at the apex of 45.degree. around the natural viewing direction. It turns out that when a pilot seeks to look at an object located on one side, he turns the head before his line of sight has moved through an angle of 20.degree. relative to the axis of the head.
The angle of 45.degree. covers any such rotation of the eye relative to its natural position and the zone of the eye to be protected.
As a general rule, helmet shells and visors are provided in a few sizes only. Pilots with very different inter-ocular spacings (in practice over the range 52 mm to 72 mm) may consequently be fitted with helmets and visors having the same predetermined outside shape. It is desirable for the visor to protect the user over all of the above range of inter-ocular spacings.
In practice, this result is often achieved by giving the central portion of the visor a shape such that its radius of curvature in the horizontal plane varies from about 145 mm in the center to about 110 mm in lateral zones, and the radius of curvature in a vertical plane parallel to the midilane of the helmet varies from about 135 mm in the center to about 75 mm in lateral zones. As a general rule, that leads to the visor being made so that all of the centers of curvature lie in a parallelepipedal volume having a width of about 30 mm and a depth of about 30 mm, with said volume being centered about 5 mm in front of the center of a line segment interconnecting the centers of rotation of the two eyes, and the centers of curvature run from the back center of the volume, for the center of the visor, to the front edg
REFERENCES:
patent: 3787109 (1974-01-01), Vizenor
patent: 3870405 (1975-03-01), Hedges
patent: 3923370 (1975-12-01), Mostrom
patent: 4978182 (1990-12-01), Tedesco
patent: 5324460 (1994-06-01), Briggs
Bertheau Fernand
Farin Eric
Keller Francois
Intertechnique
Neas Michael A.
LandOfFree
Protective equipment for the pilot of a military aircraft, and a does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Protective equipment for the pilot of a military aircraft, and a, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Protective equipment for the pilot of a military aircraft, and a will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2238287