AU729446B2

AU729446B2 - Method of manufacturing a personalized helmet

Info

Publication number: AU729446B2
Application number: AU27039/97A
Authority: AU
Inventors: Alexandre Bataille; Joel Baudou; Pascal Beaudoin
Original assignee: Thales Avionics SAS
Current assignee: Thales Avionics SAS
Priority date: 1996-04-26
Filing date: 1997-04-18
Publication date: 2001-02-01
Anticipated expiration: 2017-04-18
Also published as: AU2703997A; DE69707507T2; WO1997040716A1; FR2747895A1; FR2747895B1; ZA973631B; DE69707507D1; EP0957697A1; EP0957697B1

Description

1 METHOD OF MANUFACTURING A PERSONALIZED HELMETT The present invention applies to the manufacture of any helmet which has to be accurately positioned on its wearer's head.

Helmets with a sight are essentially used by the military for infantrymen or pilots of aeroplanes and helicopters. These helmets comprise, on the one hand, the helmet proper, intended for the passive protection of the wearer of the helmet, and, on the other hand, a display built into this helmet and intended for presenting information to the eyes of the said wearer.

In the rest of the text, the wearer denotes the person for whom the helmet is produced, even if, in certain phases of the production described, this person is bare-headed.

The helmet consists of a rigid protective shell resistant to perforation and of a thick internal cap, which is more flexible, for comfort and protection against impacts. It usually includes an audio communication system and, optionally, a breathing system, and in addition supports the display if this is a helmet with a built-in display.

The display is an optical displaying device which presents a video image of the external reality or a synthetic image on a "combiner", that is to say on a semi-reflecting screen which allows simultaneous viewing of the real world and of the image presented.

The image is produced by an image generator, for example a cathode-ray tube, a liquid-crystal screen or a matrix of light-emitting diodes. A relay optic placed between the image generator and the combiner collimates the image in order to convert it into a virtual image.

In some constructions, the "combiner" is produced by the visor of the helmet itself.

Figure 1 shows such a helmet, with its rigid shell 10 and its shockproof internal cap 12. The display 14 comprises an imager 16 (here, a projecting 2 cathode-ray tube), a protective visor 18 forming the abovementioned "combiner" and, between the imager and the visor, the relay optic The image can only be correctly viewed by the person wearing the helmet if his eyes are placed at a very precise position with respect to the optical paths defined by the display, and therefore at a very precise position with respect to all of the elements making up the display, which elements themselves must be positioned very precisely with respect to each other.

The difficulty resides in this strict positioning of the display with respect to the eyes of the person wearing the helmet.

The tolerance on the relative positioning is, for example, 1 millimetre and 1 degree between the optical system, the optical paths which it defines and the wearer's eyes.

One simple solution consists in producing a helmet with a display which can be mechanically adjusted with respect to the shell so as to adjust the position of the display to that of the wearer's eyes.

Figure 2 shows such a helmet with adjustment means 22 having four degrees of freedom, namely three translations and one rotation in elevation.

However, such an adjustment device is complex, increases the weight and size of the head equipment, and is the cause of it being problematic in use and of both its performance and reliability deteriorating over time. What is more, if the person wearing the helmet makes the adjustments himself, these may be made erroneously.

Another solution consists in transferring the adjustment from the helmet to its internal cap.

The display is then rigidly fixed to the shell and a personalized internal cap brings about both the matching of the helmet to the wearer's morphology and the correct positioning of the display with respect to the wearer's eyes.

3 The helmet is then perfectly matched to the wearer's morphology and the display is correctly placed for this wearer alone. The difficulty resides in producing this personalized internal cap, this production having to result in the display always being correctly placed without an ancillary mechanical adjustment system.

This personalization can be achieved in practice by producing a personalized lining which the wearer places inside a standard helmet. The lining may be produced by moulding directly on the wearer's head, by injecting a polyurethane foam between the wearer's head and a former which is the internal former for the shockproof cap of the helmet, whilst keeping the head and the said former in precise relative position such that the display is correctly placed with respect to the wearer's eyes. After polymerization of the foam and demoulding, a personalized lining is obtained which will be placed inside the helmet.

However, this method is tricky to use because of the pressure caused on the wearer's head by the expansion of the foam especially. This pressure causes excessive movements (of the order of 5 millimetres, while the tolerance is fixed at 1 millimetre) between the eyes and the display. It is not easily possible to compensate for this discrepancy by means of a prior shift, because the shift depends in fact on the morphology and the musculature specific to each wearer.

Moreover, the pressure and the exothermic chemical reaction of the injected foam depend on its density, that is to say on the ratio between the quantity of material injected and the actual volume lying between the head and the internal former of the shockproof cap, this volume being very difficult to measure in practice. This also leads to an uncertainty in the final positioning precision obtained.

Other drawbacks of this method also exist: pain during the operation because of the immobilizing systems used (the user must bite onto a positioning plate in order to keep his head in place) and possible headaches due to the product used and to the exothermic reaction, the method is impossible to implement if the user's morphology is outside a range of predefined morphologies, or else it is necessary systematically to increase the quantity of foam to be injected and the overall volume of the helmet in order to take into account more varied morphologies, considerable size of the equipment, the need for two or three experienced operators and a lengthy operation (several hours).

The invention aims to produce a personalized helmet in a simpler manner and by avoiding as far as possible the drawbacks of the methods of the prior art.

To do this, the invention provides method of manufacturing a helmet comprising a personalized internal cap which positions the helmet on the wearer's head, characterized by a prior determination of the shape of the wearer's head by a non-contacting measurement device, during which prior determination the position of the user's eyes is determined in three dimensions and which prior determination is followed by production of the said personalized cap on the basis of this determination.

The presence of the wearer is then necessary only for the prior determination: it is not necessary for producing the internal cap. The stresses on the wearer are much lower and the problems encountered because of the direct injection of foam onto the wearer's head disappear.

S" The prior determination is preferably performed by an optical measurement method, especially by a laser scanner which rotates about the user's head, determining the .distances between this scanner and points on the head in order to obtain the shape of the head in the form of numerical data.

0 Given that the position of the user's eyes is very important, such a determination is preferably completed by accurate measurement of the position of the wearer's eyes so as to constitute the digitized [R:\LIBLL] 10255.doc:SSL shape determination. This measurement of the position of the eyes is preferably performed by optical means.

On the basis of the shape determination, it is possible to machine or define by moulding the inside surface of the internal lining of the helmet in order to achieve personalization, that is to say that either the internal cap itself or a personalized lining, which is inserted into a standard internal cap in order to complete it, is machined or moulded.

The invention will be more clearly understood on reading the detailed description which follows and which is given with reference to the following figures in which: Figure 1, already described, is a general diagram of a pilot's helmet with a sight; Figure 2, also already described, shows an embodiment of a helmet of the prior art; Figure 3, also already described, shows a helmet with a personalized lining in a use situation; Figure 4 shows a device for determining the shape of the head, providing a numerical determination, by rotation of a measurement apparatus about the head; Figure 5 shows a mould for a personalized lining with its standard parts and its personalized internal mould.

The preferred implementation of the invention will now be described. In this implementation, a personalized lining, which is to be inserted between the head and the standard (non-personalized) shockproof cap of the helmet, is produced. However, it will be understood that a personalized shockproof cap could also be produced directly.

Figure 3 shows a helmet on the head of its wearer 36, with its shell 30 and its standard internal cap 31 in which a lining, composed of a foam 34 with flocking 35 on the wearer's head side, is placed with the aid of positioning studs 32 and 33.

Figure 4 shows the preferred implementation of the invention. In this implementation, the 6 determination of the shape of the wearer's head is a non-contacting numerical determination, such as for example a two-dimensional numerical determination obtained by a 3-D scanner digitizing profiles formed by a plane laser beam.

Such a determination of the shape of a head may consist of digitization of meridians illuminated by the laser and captured by a camera in a rotary digitizing head 52 which rotates about a vertical spindle 53 of a fixed platform In order to facilitate digitization of the shape of the head by such a scanner, the wearer wears, for example, a thin elastic cap intended to press his hair against his skull, as the helmet would do, this thin elastic cap having a colour and a surface finish which are tailored to the scanner.

Next, the wearer is placed in an armchair whose backrest is inclined in a manner representative of the aeroplane's seat. The wearer is placed in a natural posture of the head, fixing his gaze in the horizontal while looking at his image in the semi-reflecting mirror 54 placed in front of him. His head is kept in a stationary position by a biting plate, a chin rest or an adjustable ergonomic brace which has six degrees of freedom and is connected to the armchair.

The armchair is movable with respect to the fixed platform 55 and is moved in the horizontal plane so as to make the crown of the subject's skull coincide with the mechanical rotational axis 53 of the scanner and then adjusted in terms of height so as to optimize the shape determination and to reduce the areas of shadow.

Complete digitization of the head may be carried out in one revolution of the scanner in 15 seconds.

The average resolution of this digitization is about 0.5 millimetres and the accuracy of the order of 0.1 millimetres.

7 The session finishes by measuring the spatial coordinates of the eyes and of possible anatomical features, by means of sightings using various telescopes.

In order to allow strict positioning of the display of the helmet with respect to the wearer's eyes, the device in Figure 4 measures the position of the centre of each of the wearer's eyes with respect to the fixed platform Each of the three sighting telescopes 56, 57 and 58 is placed on a digital-coding linear rule, respectively 59, 60 and 61, these rules making it possible to measure two coordinates of a point on the wearer to be digitized. The system of digital rules..and of telescopes is positionally harmonized beforehand with the digitization determination by the scanner with the aid of a calibration piece.

The wearer maintains his fixed gaze using the semi-reflecting mirror 54 placed in front of him.

A telescope 56 is placed in front of the wearer's face and enables an operator to determine the coordinates of the wearer's eyes in terms of height and in terms of width by adjusting the position of this telescope.

The other two telescopes 57 and 58, which are orthogonal to the telescope 56, are placed on either side of the wearer so that the operator measures the depth value, on the one hand, of the left eye by adjusting the position of the sighting telescope 57 and, on the other hand, of the right eye by adjusting the telescope 58.

Next, the digitization of the wearer's head is used to produce the personalized lining defined hereinabove, as well as internal elements of the helmet such as, for example, the position of the headphones.

This digitization may be used by a numericalcontrol machining in order to machine an internal mould for the lining.

8 Production of a lining mould is shown in Figure 5 and comprises, on the one hand, a standard base 63 into which a personalized internal mould 64 is inserted and, on the other hand, a standard external mould 65, corresponding to the inside shape of the standard shockproof cap of the helmet.

The internal mould has a standard internal surface 67, enabling the said mould to be accurately positioned with respect to the base 63, and a personalized external surface 66 representing the shape of the wearer's head. The external mould 65 fits onto the base so as to obtain a space corresponding to the lining between the external mould 65 and the internal mould 64. The lining is thus produced by injection.via the orifice 68 when the two moulds 65 and 64 are locked onto the base 63. Centring studs are formed on the lining during this moulding operation by filling the cavities 69 and The lining may also be produced from a foam block by machining with the aid of a numerical-control machine using the above digitization, followed by dressing by a comfort-providing finishing step.

After manufacture, the personalized lining is placed in a standard helmet.

Such a helmet-manufacturing method allows production of a helmet with a built-in display tailored to the wearer without the addition of a mechanical device for adjusting the display.

It allows separation, in time and in space, of the two main production steps consisting, on the one hand, of determining the shape of the head and, on the other hand, of producing the personalized lining.

The shape determination described in the preferred implementation of the invention is clean and not very stressful for the wearer since there is no pressure exerted on his head, as in the production of the lining by moulding directly right on the wearer's head, immobilization being painlessly provided by a simple biting plate without taking a dental impression.

9 The necessary determination of the shape of the head is more precisely limited to determining that part of the head which serves to define the personalized lining.

The first step requires the wearer to be present, but only a few tens of minutes, and, for greater convenience, a device for determining the shape of the head may be installed, for example, in a lorry in order to enable the determinations to be made at the helmet wearers' place of work.

The second step takes place without the wearer, for example in a factory, since the adjustment of the helmet on the wearer's head is defined in the first step.

Spare linings may be provided on request, without the constraint of having the wearer present.

Likewise, it is possi-ble to incorporate options into the lining production without repeating the shape- taking step, such as for example the choice of the material of the lining, the choice of. the finishing fabric, the choice of the type of helmet or even the choice of the position of the display in terms of elevation.

Another advantage of the invention is the fact that the prior shape determination enables the quantity of material to be injected in order to produce the personalized cap to be ascertained in advance.

Claims

1. Method of manufacturing a helmet comprising a personalized internal cap which positions the helmet on the wearer's head, the method including a prior determination of the shape of the wearer's head by a non-contacting measurement device, during which prior determination the position of the user's eyes is determined in three dimensions and which prior determination is followed by production of the said personalized cap on the basis of this determination.

2. Method according to claim 1, wherein the prior determination of the shape of the wearer's head is performed by a 3-D optical scanner.

3. Method according to claim 1 or 2, wherein the personalized cap is machined with the aid of a numeral-control machine on the basis of the prior shape determination.

4. Method according to claim 1 or 2, wherein the personalized cap comprises a standard cap into which a personalized lining is inserted.

5. Method according to claim 1 or 2, wherein a mould for a personalized cap is produced from the determination.

6. Method according to claim 4, wherein a mould for a personalized lining o 25 is produced from the determination.

7. Method according to any one of claims 1 to 6, wherein the position of the eyes is measured by a device determining at least the coordinates of the eyes in terms :of height and in terms of width and the depth of each of the eyes. S 8. Method according to any one of claims 1 to 7, wherein the position of 0. the eyes is determined by an optical device. 4 RA 9. Method according to any one of claims 1 to 8, wherein the head is F immobilised during the determination of the shape and of the position of the eyes. [R:\LIBLL] 10255.doc:SSL 11 Method according to any one of claims 1 to 9, wherein the helmet comprises a built-in display device requiring very precise positioning with respect to the wearer's eyes.

11. Method of manufacturing a helmet comprising a personalized internal cap which positions the helmet on the wearer's head, the method substantially as hereinbefore described with reference to Figs 4 and 5 of the accompanying drawings. Dated 15 November, 2000 Sextant Avionique Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON *o *ot *ot ft*f ft*tftf [R:\LIBLL] 10255.doc:SSL