DEPOLARIZING LAYER"

DESCRIPTION

[0001]The subject of the present invention is a protective helmet equipped with an eye visor for the practice of sports activities and/or the use of motorized vehicles. [0002]Protective helmets often include a protective eye visor. In some cases this visor is only intended to protect the user's eyes against the entry of debris, dust, or simply against the wind. In other cases, however, the visor also provides protection against excessive light.

[0003]Generally, protection from light is achieved simply through the use of pigments that cause the visor to transmit only a fraction of the incident light. Filters of this type are generally classified into categories (SO, SI, S2, etc.) with increasing levels of absorption. However, in many situations, the user needs to have a level of light filtering that varies according to the different levels of external brightness, such as in the case of a motorcyclist going from a sunny area through a tunnel.

[0004]Technologies that seek a solution to this problem are known. However, such known technologies have limitations that actually make them ineffective. [0005]Photochromatic lenses are known to be made with treatments or materials that react to sunlight causing the lens to darken. Such known lenses, however, are all too slow to react to very rapid changes in brightness. Furthermore, the optimal substrate on which to carry out such treatments is glass, which is a material that is hardly compatible with protective devices.

[0006]Electrochromic lenses are known that typically use polymers that may change optical properties when a magnetic field is applied. Said lenses, while faster than photochromatic lenses, are still quite slow. Moreover, the high power required to achieve the change of state limits the maximum number of possible changes, making this type of lens functional for automatic adaptation to ambient light only in the presence of bulky batteries.

[0007]Finally, lenses that use layers of liquid crystals are known, and they are the only ones that are able to react quickly to changes in ambient light. However, lenses of this type are still substantially unused, given the persistence of a number of issues, including: low maximum brightness of the filter, presence of unwanted polarizations, interference with other transparent elements, and undesirable reactions to mechanical stresses. For these reasons, said lenses find application in the field of protective devices for welding, wherein TN (twisted nematic)-type planar liquid crystal LC screens are widely used. However, said screens are not suitable for sunlight protection under normal conditions, being in fact too dark in their maximum transmission state and having a very small field of vision.

[0008]Device application techniques using GH (Guest-Host)- type liquid crystals are also known. This type of liquid crystal does not use polarizing filters and may therefore achieve transparencies much greater than 50 percent, making it potentially more suitable for use in sunlight protective devices under normal conditions. However, there are a number of issues with this type of lens as well. In fact, GH-type liquid crystal LC filters react to mechanical stresses by creating unwanted inhomogeneities in the level of transparency. Most existing helmet visors are made in such a way that, when a GH-type LC layer is applied to them, said layer undergoes such deformations and mechanical stresses that the uniformity of its transparency is compromised. Furthermore, helmet visors are typically made using the injection molding technique, which generates parts with residual internal stresses that interfere with the liquid crystals, creating a birefringence effect typically called "rainbow" that makes the vision uncomfortable. [0009]The object of the present invention is to solve the problems found in the state of the art in order to obtain a helmet equipped with a variable transparency visor that is truly effective and comfortable to use.

[0010]Said object is achieved by a protective helmet according to claim 1. The dependent claims disclose further advantageous embodiments of the invention.

[0011]The features and advantages of the protective helmet according to this invention will become apparent from the following description, given as a non-limiting example in accordance with the accompanying drawings, wherein:

[0012]- Fig. 1 is a side view of a protective helmet according to the present invention in one embodiment; [0013]- Fig. 2 is a cross-sectional view of the protective helmet of Fig. 1; [0014]- Fig. 3 shows a detail of the visor of the helmet of Fig. 1;

[0015]- Fig. 4 is a side view of a protective helmet according to the present invention, in a further embodiment; [0016]- Fig. 5 is a cross-sectional view of the protective helmet of Fig. 4;

[0017]- Fig. 6 is a cross-sectional view of the protective helmet from Fig. 1, in a further embodiment;

[0018]- Fig. 7 shows a detail of the helmet visor of Fig. 6; [0019]- Fig. 8 shows an exploded diagram of the structure of the lens assembly of the visor of the protective helmet according to the present invention.

[0020]With reference to the appended figures, 1 has been used to collectively denote a protective helmet equipped with a visor for the eyes for the practice of sports activities or the use of motorized vehicles according to the present invention.

[0021]The helmet 1 comprises a cap 2, protecting at least part of the user's head, to which is engaged a visor assembly 3, protecting the user's eyes.

[0022]The cap 2 comprises a rigid outer shell 21, such as made of plastics or composite, and a collapsible inner shell 22, such as made of polyurethane foam or expanded polystyrene.

[0023]The inner shell 22 is covered, on the side intended to be in contact with the user's head, with padding, made mainly of fabric, adapted to improve comfort during the use of the helmet. [0024]Preferably, the cap 2 is equipped with a communication system. For example, the helmet 1 comprises a bone conduction audio system.

[0025]Preferably, the cap 2 may also include additional components typical of a helmet, such as vents, spoilers, aerodynamic appendages, signal lights, communication systems, and displays.

[0026]The cap 2 has a frontal opening 23 at the user's eye region, which is intended to be closed by the visor assembly 3 at least when the helmet 1 is being used. Said opening is characterized by a closed perimeter in the case of full-face helmets (as in Fig. 1), while it takes the form of a recess in the perimeter of the cap in the case of helmets without chin guards (as in Fig. 4).

[0027]The cap 2 has, on both sides, a seat arranged near the region of the user's ear, adapted to accommodate a corresponding anchor pin 32 of the visor assembly 3 so that said assembly is pivoted on the cap 2 to open and/or close the opening 23.

[0028]In one embodiment, the visor assembly 3 is attached to the cap 2.

[0029]In a further embodiment, the visor assembly 3 is removable from the cap 2, for example, to be replaced with a different visor assembly to adapt the helmet 1 to specific lighting situations. [0030]The visor assembly 3 comprises a variable transparency lens assembly 4 that is truly effective and comfortable in use.

[0031]In one embodiment, the lens assembly 4 is directly attached to the cap 2. [0032]In a different embodiment, the visor assembly 3 comprises a frame 31 engageable to the cap 2 and adapted to support the lens assembly 4. Therefore, in this embodiment a frame 31 is applied to the lens assembly 4, and in particular to a structural lens 41, which at least partially follows the perimeter of said structural lens 41.

[0033]In the embodiment in Fig. 1 and 4, the visor assembly 3 comprises a frame 31 that is engageable to the cap 2 by means of a pair of anchor pins 32 that are insertable into the appropriate seats of the cap 2.

[0034]In the embodiment of Fig. 1, the frame 31 completely surrounds the lens assembly 4 of the visor 3. In said embodiment, the cap 2 also comprises a chin guard, fixed or flip-up, to cover the user's chin. In said embodiment, the helmet 1 is a full-face helmet.

[0035]In the embodiment in Fig. 4, the frame 31 only partially surrounds the lens assembly 4 of the visor 3. In fact, as may be seen, the lower part of the lens assembly 4 is without a frame 31. In said embodiment, the cap 2 has no chin guard covering the user's chin, which therefore remains uncovered. In said embodiment, the helmet 1 is an open or non-full-face helmet.

[0036]The lens assembly 4 comprises a structural lens 41 or outer lens. The structural lens 41 is at least partially transparent. Said lens may be made with transparent materials and without the addition of pigments resulting in a light transmission close to 100 percent. Or it may be made by using materials or combinations of pigments, materials, and surface treatments in such a way as to filter out some of the non-visible light or radiation, even possibly unevenly over the whole spectrum to achieve optimal vision under different environmental conditions.

[0037]In the case of the frame 31, the structural lens 41 is attached to the frame 31, for example, by interlocking, gluing, by the use of magnets, or by the interposition of double-sided adhesive film.

[0038]Preferably the structural lens 41 is made of plastics material, such as polycarbonate or polyamide. [0039]In an embodiment intended for use in specific lighting conditions, the structural lens 41 is pigmented to modulate the absorption spectrum, specifically in this case the structural lens 41 may also be pigmented to modulate the contrast in specific lighting situations, for example by increasing it.

[0040]As shown in Fig. 8, the structural lens 41 has an outer surface 411 and an inner surface 412.

[0041]Preferably, the outer surface 411 of the structural lens 41 is treated with a coating, such as an anti- scratch, and/or mirroring, and/or anti-reflective, and/or multilayer coating.

[0042]The lens assembly 4 comprises a liquid crystal film 43 (hereinafter LC film), provided with an outer face 431, facing the structural lens 41, and an opposite inner face 432.

[0043]The LC film 43 is of the GH (Guest-Host) liquid crystal type. In this type of LC film, dichroic pigments are dispersed in a matrix of liquid crystals; the magnetic field drives the orientation of the liquid crystals, which, in turn, drive the orientation of the pigments. Typically in the "active" state, the crystals assume a helical configuration and the pigments are arranged in planes parallel to the film surface, while in the "inactive" state crystals and pigments are arranged perpendicular to the surface of the film.

[0044]Preferably, the LC film 43 has a visible light transparency of at least 60 percent in the lightest state thereof and at most 40 percent in the darkest state thereof. For example, the LC layer may have a transparency of about 30 percent in the darkest state thereof and about 70 percent in the lightest state thereof.

[0045]The LC film 43 is controlled by an electronic board 5, described below, which produces a signal, the intensity of which increases with the increase in ambient light.

[0046]Preferably, the LC film 43 is mounted in back of the structural lens 41, i.e., on the side of the inner surface 412, preferably using optically clear adhesive (OCA).

[0047]In one embodiment, shown for example in Fig. 1, the structural lens 41 has a cylindrical curvature, that is, it is curved on a single axis. Advantageously, this shape allows the LC layer 43 to be laminated to the structural lens 41 in an optimal manner.

[0048]In one embodiment, the shape of the LC film 43 is contained in the shape of the structural lens 41. Therefore, the portion of the shape of the structural lens 41 not covered by the shape of the LC film 43 defines a free edge 413. Advantageously, this configuration avoids contact between the LC film 43 and the sealing gasket 49, as shown in Fig. 7. In the example wherein the visor assembly 3 has no frame, the free edge of the structural lens 41 not covered by the LC film 43 is at least partially covered by a covering layer. In the example wherein the visor assembly 3 has a frame, the free edge of the structural lens 41 not covered by the LC film 43 is at least partially covered by said frame.

[0049]In one embodiment, shown in Fig. 6, structural lens 41 has a recess, made in the inner surface 412, in which the LC film 43 is positioned, which is then embedded in the structural lens 41. In said embodiment, the free edge 413 of the structural lens 41 is at least partially covered by a covering layer 414. Therefore, the area of the visual field outside the LC film 43 is obstructed by applying a covering layer 414 to the structural lens 41. [0050]Preferably, internally to the LC film 43, i.e., on the side of the inner face 432, anti-fog and/or anti reflection treatments, or a real additional layer equipped with anti-fog and/or anti-reflection treatment, may be applied.

[0051]In an embodiment shown in Fig. 8, the lens assembly 4 comprises a depolarizing film 42 arranged externally to the LC film 43, that is, at the outer face 431. The depolarizing film 42 is then arranged between the structural lens 41 and the LC film 43.

[0052]The depolarizing effect is preferably achieved by birefringent film characterized by a wave phase shift between the two optical axes greater than 1500 nm. [0053]The visor assembly 3 comprises an electronic board 5 adapted to control the LC film 43. The electronic board 5 comprises a photovoltaic cell and an electronic circuit powered by the photovoltaic cell. In one embodiment, the electronic board 5 comprises a single photovoltaic cell, arranged in front and center, and two integrated circuits positioned at the rear, sides, and on either side of the photovoltaic cell. Preferably the photovoltaic cell operates simultaneously as a sensor of the amount of light in the environment and as a power supply for the LC film; in fact, the greater the amount of light that strikes the photovoltaic cell, the higher the power generated by the photovoltaic cell; the power with which the LC film is fed is consequently higher and said LC lens darkens more. [0054]Preferably, the response curve between the input signal and output signal from the electronic board 5 may be changed according to the user's needs.

[0055]Advantageously, the photovoltaic cell is located close to the structural lens 41, thus receiving more light. Specifically, the electronic board 5 with the photovoltaic cell is located to the rear of the structural lens 41, and the photovoltaic cell faces the structural lens 41.

[0056]Optionally, the structural lens 41 has a multilayer mirroring treatment.

[0057]The electronic board 5 is positioned internally with respect to structural lens 41. Advantageously, the photovoltaic cell receives filtered light from the structural lens and thus reacts to the same component of ambient light that the user's eye receives, net of the intervention of the LC film.

[0058]The electronic board 5 is arranged in a compartment 33 located outside the perimeter defined by the frontal opening 23 of the cap 2, so that, when the visor 3 is lowered, the electronic board 5 is outside the perimeter of the opening 23 and does not result in a significant reduction of the user's field of vision. Advantageously, therefore, the photovoltaic cell is positioned so that it is in an area of the user's field of view that is already occluded by the cap 2 of the helmet 1.

[0059]Preferably the compartment 33 is sealed i.e., leak- proof, and protects the electronic board 5; said board may alternatively or additionally be protected by protective coatings or embedded in resins. [0060]In a frameless embodiment (Fig. 6), the compartment

33 is made between the structural lens 41 and a rear protective shell.

[0061]In an embodiment with frame (Fig. 2,3,5), the compartment 33 is arranged in an upper portion of the frame.

[0062]In one embodiment, the helmet 1 includes a battery that may provide more power to the electronic board 5; possibly, this battery may also be used to power other electronic devices such as traditional or bone-conduction audio systems, intercoms, "head-up" or traditional displays, signal lights, emergency call systems, cameras, or sensors.

[0063]Preferably, the cap 2 comprises a photovoltaic sheet positioned at least partially on the outside of the outer shell 21. Preferably, the photovoltaic sheet is a flexible sheet deformed to follow the curvature of the cap 2. Preferably, the photovoltaic sheet is connected to the battery.

[0064]In summary, therefore, the protective helmet 1 for sports or motorized vehicle use according to the present invention comprises:

[0065]- a protective cap 2, which, when the helmet is worn, protects at least part of the user's skull;

[0066]- a structural lens 41, which is at least partially transparent;

[0067]- a GH-type LC film 43 positioned internally to the structural lens 41;

[0068]- a depolarizing film 42 placed between the structural lens 41 and the LC film 43. [0069]The depolarizing film eliminates interference between the LC 43 layer and the internal stresses present in the structural lens 41 and makes vision comfortable and uniform.

[0070]Advantageously, the protective helmet 1 for sports or motorized vehicle use according to the present invention is equipped with a visor with variable transparency that is truly effective and comfortable in use.

[0071]It is understood that a person skilled in the art, in order to meet contingent needs, could make modifications to the device described above, all of which are contained within the scope of protection as defined by the following claims.