REAR-VIEW DEVICE INCORPORATABLE IN HELMETS AND THE LIKE

Abstract: A rearview device is integrated within a helmet and pres­ ents an objective O₁, an eyepiece O₃ and means for optically coupling together said elements, comprising either optical fibres F or an intermediate objective O₂, and at least a mirror M. Moreover, the mirror is of the roof type configuration.

Description: Application for Patent under the European Patent Convention Title: REARVIEW DEVICE INCORPORABLE IN HEliflETS AND THE LIKE DESCRIPTION The present invention relates to a rearview device incorporable in helmets and the like, for example in protective helmets used by motorcyclists and for sports in general, with particular reference to,but without any limitation to protective helmets. The increasa in road traffic presently causes all vehicle drivers when undertaking a manoeuvre, e.g. when turning or overtaking, to locate exactly all the vehicles that follow or precede. The rearview mirrors applied inside the vehicle enable the driver, by means of a slight inclination of the head, to explore rearwards a field covering an angle of about 300 and to observe the vehicles in the field of vision. Generally these rearview mirrors are Integrated by a second rearview mirror, applied externally to the vehicle, the field of which completes that of the first rearview mirror, permitting the driver to "follow", for a few instants, the vehicles that are overtaking him. Besides these various advantages, said devices present, however, some inconveniences i.e.: - their field vision is fixed and dependent on the direction of movement of the vehicle; - the protrusion of the external rearview mirror makes this a fragile and dangerous accessory; - the observation through the rearview mirror demands an inclination of the head with consequent momentary abandonment of the direct vision of the objects situated in front of the driver. In the case of two-wheeled vehicles, i.e. motorbicycles and motorcycles, the rearview mirror is fixed to the handle,whereby all the inconveniences cited hereabove occur. The present invention concerns a rearview device the essential characteristics of which consists in the fact that it can be integrated within the helmet which protects the driver's head and is able to offer, on the models presently in use, the following advantages: A) the field of vision towards the rear may be ampli fied at will by means of a simple orientation of the driver's 3:lyad; B) the use of protruding, fragile or dangerous members or parts is not required; C) the image is observed in proximity of the normal vision axis, with the overlapping or juxtaposition of the objects located in front and seen without the aid of the device; D) this device may be easily fitted to any type of helmet maintaining practically unaltered the structural strength of the helmet. The rearview device presents supporting means which may be fitted to the helmet and which support, in the rear part of the helmet, an objective the optical axis of which is generally horizontal, and in the front part, at least an eyepiece, and presents means to optically connect the objective and the eyepiece so as to permit the vision of the rear objects. According to this invention, the optical elements of the rearview device form an objective which provides, in its focal plane, an image of the rear objects which are to be observed and an eyepiece which permits the observation of said image according to a desired enlargement factor. The objective, backwards, is located in the upper part, or on one of the side walls of the helmet. The eyepiece is fitted in the front part of the helmet and, ob mousy, in such a position as to be seen by the eye of the driver. The optical connection between the objective image and the eyepiece image is obtained, in accordance with the invention, by means of a connecting system comprising an optical fibre and an intermediate objective, or by reflecting and/or refracting means such as mirrors or prisms the combination of which must fulfill the following requirements: - the final image observed by the driver through the eyepiece must be a "true" one, i.e. the top and bottom, the right and left hand side of the rear object,as seen in the field of vision of said eyepiece, must be maintained; - the optical system which generally follows a profile corresponding to that of the helmet, to which the rearview device is connected, is made in such a manner that the elements of said rearview device may be easily fitted in the helmet. Some examples of the embodiment of this rearview device are described further on with reference to the attached drawings in which: - Figure 1 shows a side and partial elevation view of a helmet provided with a rearview device in which the coupling means between the objective and the eyepiece are constituted by optical fibres. - Figures 2 and 3 are variations of the embodiment as shown in Figure 1, in which the coupling means are of the reflecting type; and - Figure 4 is a schematic top view of a reflecting ele ment of the rearview device shown in Figures 2 and 3. In the various figures, the same components bear the same references. In these Figures, the helmet A presents, in the upper rear section, an aperture A1 in allignment with an objective Oi held by the helmet structure by means of support B1. In Figure 1, the objective On has its focal plane coinciding with the input face F1 of an optical fibre element F the output face F2 of which is in allignment with the intermediate objective 02 and with a deflecting mir- ror M1 coupled with an eyepiece 03. The rearview device representedDn Figure 2 is more simple than that shown in Figure 1. The objective Oi is coupled with a field lens V located at the input of a reflecting system M-N clearly illustred in Figure 4. Said reflecting system presents two mirrors M and N with their reflecting faces placed at right angles and in such a manner that their meeting line is practically vertical. Still considering Figure 4, the incident beam R1 fdlllowing, in a vertical plane, a path inclined downwards, meets the mirror M and is reflected at right angle, forming a downwards inclining beam R2 but always remaining in a vertical plane parallel to that of the incident beam R. Said double reflection caused by the two faces of the reflecting system M-N shifts horizontally the vision plane and causes it to pass from the medium plane of the helmet to that of the driver, resting a reversal - from right to left - of the observed image. The horizontal reversal of the image from objective On completes the vertical reversal caused by the mirror M and allows the observation through the eyepiece 0 of a t'true" image. The reflecting system N-N may comprise trapezoidal mirrors in order to reduce the volume of said system, said mirrors inscribing into the conical beam which covers the field of the image, starting from the eye of the driver. The use of the reflecting system M-N ensures, besides a deviation effect, a lateral reversal of the image. With further reference to the rearview device shown in Figure 1, the objective Or presents small overall dimensions and is pointed towards the rear part of the helmet A, said objective having an optical axis which is generally horizontal. This objective gives a real inverted image I1 of the objects situated behind the driver, said image being situated in the focal plane of the objective. The focal distance of the objective Ol is chosen in such a manner as to cover a field of about 300, said distance corresponding, for example, to 10 mm. for an image having a diameter of 4 mm. The optical fibre F generally has the same diameter and is held in place by supports B2 which follow the profile of the helmet0 Said optical fibre transmits image I1 fro the rear part to the front part of the helmet, without deforming the image and without loss of luminosity, whereupon the image 12 appears at the opposite end thereof. Said image I2, identical to image I1, is received by an intermediate objective 2 forming image 13 enlarged about 5 times with respect to image 13 i.e. an image covering a surface having a diameter of about 20 mm. An eyepiece 03 placed in proximity of the eye E of the driver, permits the vision without any strain due to adaptation, of the image 13 in a direction deviated by means of a deflecting mirror M1 so that said image can be near the normal vision axis of the objects placed in front of the driver. A field lens V, placed in the plane of the image I3, concentrates the beam light coming from the objective 2 towards the eyepiece 03. With a helmet equipped with said rearview device it is-possible to observe almost simultaneously the vehicles located in front of and behind the driver. In the embodiment shown in Figure 2, the objective Oi occupies a position identical to that of the objective Ol in Figure 1. However, in this case the focal distance is larger i.e. it is for example equal to 70 mm. so as to form an image having a diameter of about 25 mm. for a field in the order of 300. The optical axis after the real, inverted image I3, is deviated doamwards by about 700 by means of a reflecting system M-N as cited above, which ensures also the lateral reversal of said image which is directly observed by the eyepiece 02. As in the previaus example, the optical axis is deviated by means of mirror M, in a direction close to the normal vision axis of the objects situated in front of the driver. Moreover, the field lens V situated in the plane of the image I3 permits to concentrate the beam light coming from the objective 01 on the eyepiece 02. In the example of Figure 3 the reflecting system M-N presents the mirrors M and N situated in a position inverted with respect to the corresponding elements of-the rearview device in Figure 2. In the examplesof the embodiments previously described, the rearview devices may be duplicated in order to obtain two parallel circuits 65 mm apart, this corresponding to the average distance between the eyes K, of a human, thus ensuring a binocular and stereoscopic vision of the image observed. Needless to say the rearview device as described and illustrated hereabove may be modified and adapted with particular reference to the type of helmet to which said rearview device is being applied within the scope of the present invention.

Claims: CLAIMS 1. A rearview device for helmets in general and for pro tective helmets in particular, characterized in that it presents supporting means which may be fixed to the structure of the helmet and holding, in the rear part of the helmet, an objective the optical axis of which is generally horizontal, and in the front part at least one eyepiece and means for optically coupling said eye piece and said objective in order to permit a "true" vision of the objects situated in the rear. 2; A rearview device according to claim 1, characterized in that the means utilized for optically coupling said eyepiece and said objective comprises an optical fibre the inlet face of which is situated in the focal plane of the image of the objective while the outlet face is combined with an intermediate objective to transfer the enlarged image in the focal plane of the eyepiece, while a plane mirror reflects the image in the vision direc tion. 3. A rearview device according to claim 1, characterized in that said means for optically coupling said eyepiece and said objective comprise reflecting and/or refrac ting means collocated one with respect to the other ir such a manner as to obtain a reflection and the recti fication of the image in the vision direction. 4. A rearview device according to claim 3, characterized in that it comprises at least one mirror and 8 double mirror the reflecting surfaces of which are collocated almost at right angles. 5. A rearview device according to one or more of any of the preceding claims 1 through 4 characterized in that the supporting means fixed to the structure of the helmet support a double optical system the branches of which are situated parallel to each other and symmetrically with re spect to the median plane of the helmet, the elements of said branches being placed apart at a distance generally corresponding to the average distance between the eyes of a human, thus ensuring a binocular vision of the image observed. 6. A protective helmet characterized in that it comprises a rearview device according to any one or more of claims 1 to 5. 7. A helmet according to claim 6 characterized in that the optical axis of the objective-eyepiece system, according to any one of the preceding claims 1 to 5, is situated in the longitudinal plane of symmetry of the helmet or in a position which is equidistant from said plane.

Inventors: PICQUET, LAMBERT, CUVILLIER, ROGER, PICQUET, JEAN MARIE
Applicants: CUVILLIER, ROGER, PICQUET, JEAN MARIE, PICQUET, LAMBERT
Application year: 1979
Main classification: A42B3
IPC codes: G02B27, A42B3, G02B17, G02B5