GB2283333A

GB2283333A - Divers mask having a display

Info

Publication number: GB2283333A
Application number: GB9421858A
Authority: GB
Inventors: John Charles Irvine
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-10-29
Filing date: 1994-10-31
Publication date: 1995-05-03
Also published as: GB9421858D0

Abstract

An information display is made visible to a diver wearing a mask 10 by reflecting an image off a front lens 22 of the mask so that the image appears to be focused to the front of the diver beyond the mask. Focusing means within a housing 26 on one side of the mask enables the image size and distance to be varied, to suit the diver's circumstances. A battery pack 46 for the display may be mounted on the opposite side of the mask to balance the mask. The mask lens may be of a sandwich construction comprising an inner layer of photochromic glass (76, Fig. 6) applied to a layer of tempered glass (74, Fig. 6) bearing a semi-reflective coating. <IMAGE>

Description

DIVERS' MASK The present invention relates to a divers' mask and in particular to a divers' mask incorporating display means to present visual information to a diver wearing the mask.

While carrying out a dive, a diver must have access at all times to vital, safety-critical information. The diver uses this information to, amongst other things, avoid decompression sickness (the bends), nitrogen narcosis, and running out of air.

Conventionally, this information may be presented to the diver by a dive computer which may typically be mounted on a wrist strap or on a console attached to the diver's air supply apparatus.

Conventional dive computers have several disadvantages: when wrist-mounted, they are prone to loss; when console mounted, they may get caught in obstructions; in both cases, they may be difficult to read in an emergency or when both of the diver's arms are otherwise occupied.

It is known from US-A-5033818 to provide in a divers' mask an information display made visible to a diver wearing the mask outside of the normal field of vision of the mask by reflecting towards the diver's eyes, through a plurality of mirrors, the image of an electronic display. However, this arrangement appears to be unsatisfactory in use because (a) the diver's eyes must re-focus when their attention is moved between the closely-positioned display and the outside world; (b) the system is susceptible to disruption by water entering the mask; and (c) the display apparatus is cumbersome in use.

The aim of the present invention is to provide a divers' mask which has display means to present information to a diver wearing it which can be viewed clearly, which may be satisfactorily cleared of water by the diver even when submerged and which does not restrict the diver's movements or vision.

According to a first aspect of the invention there is provided a divers' mask having display means operative to generate a data display visible to a diver wearing the mask wherein there is provided focusing means arranged to cause the image of the data display to appear to be focused to the front of the diver beyond the mask.

In this way, the required re-focusing of the diver's eyes when they move from looking at the display to the outside world is minimised.

Preferably, the focusing means is adjustable such that the distance to which the diver's eyes must focus to read the display corresponds with the distance to which the diver's eyes must focus when viewing the general surroundings in which he or she is working.

The focusing means may comprise a first lens to modify the perceived size of the displayed information and a second lens to focus the image at the required distance.

In a preferred embodiment, the display means comprises a luminescent or an illuminated display, a visible image of which is projected by the focusing means.

Typically, the focusing means directs an image towards a front lens of the mask, the diver viewing a reflection of the image from the inner surface of the front lens. The front lens may be semi-reflective to enhance reflection of the image.

Preferably, optical surfaces within the display means and the focusing means, and the internal surface of the front lens of the mask are coated with a water-repellant and/or anti-mist coating. The coating composition sold as Ritec (R.T.M.) may be suitable.

From a second of its aspects, the invention provides a divers' mask having display means operative to display information visible to a diver wearing the mask, in which the display means is integrated into the mask.

This aspect of the invention allows the diver to remain unincumbered by trailing leads or other equipment additional to the normal mask and breathing apparatus.

Preferably, any apparatus required to support the display means such as a power supply, environmental sensors, and so forth, is also integrated into the mask.

In one embodiment of this aspect of the invention, the display means and a battery pack there for are mounted at opposite sides of the mask so arranged as to be disposed on opposite sides of the wearer's head.

This arrangement allows the weight of the mask to be balanced, or approximately balanced, about the centre-line of the wearer's head.

The display means may preferably be viewed while the mask is held in a hand so that information may be read from the display without the need to don the mask.

An embodiment of the invention will now be described in detail by way of example with reference to the accompanying drawings, in which: Figure 1 shows a divers' mask embodying the invention; Figure 2 is a schematic plan view of the optical components of the mask of Figure 1 as worn by a diver; Figure 3 is an example of the view presented to a diver wearing the mask of Figure 1; Figure 4 is a block diagram of an electronic control system for the mask of Figure 1; Figure 5 is a diagram of the optical arrangement of a display means of the mask of Figure 1, as arranged within a housing of the mask; and Figure 6 is a diagram of an alternative optical arrangement for the display means.

With reference first to Figure 1, a divers' mask 10 comprises a face mask 12 of rubber or artificial rubber, and a securing strap 14.

The face mask 12 is shaped to fit over the eyes and nose of a diver wearing the mask 10. The face mask 12 has a curved, inner lip 16 which forms an airtight and watertight seal against the wearer's face and a nose portion 18 which covers and seals the wearer's nose. Left and right front planar lenses 20,22 of transparent material are provided in the face mask 12 positioned to provide the wearer of the mask 10 with forward vision. The securing strap 14 extends around the rear of the wearer's head to secure the face mask against the face of the wearer.

The mask, insofar as it is described above, is of similar arrangement to a conventional divers' mask.

In the mask of the present embodiment, there is further provided display means. The display means comprises a housing 26 mounted on the face mask 12.

The housing 26 is a generally cylindrical tube of metal, and is disposed forward of the right ear of a diver wearing the mask 10. The housing 26 extends through the face mask 12 such that an inner end portion of it is, in use, within the dry environment within the mask 10 and an outer end portion 28 of it is outside of the mask 10 and is accessible while the mask 10 is being worn. The end of the housing 26 within the mask 10 is open.

It will be understood that many other arrangements of the display means are possible within the invention. For example, the housing may be of plastics or may be dispensed with altogether, the display and its associated optical components being contained within a suitably-shaped integral portion of the face mask.

The arrangement of the housing 28 and of the lenses 20,22 in relation to the head 30 of the wearer of the mask 10 is shown schematically in Figure 2. It will be seen that the housing 26 is inclined inwardly of the straight-ahead line of view CL of the wearer in the general direction of the wearer's view, and the lenses 20,22 of the mask 10 are each disposed with their planes directed to intersect close to the nose of the wearer.

Within the housing 26 there is disposed an illuminated display 36, and optical focusing means to project an image of the display 36 towards the right lens 22. From the right lens 22, the image is reflected towards the right eye of the wearer, the image being superimposed upon the wearer's view of the outside world as illustrated in Figure 3.

The arrangement of the display 36 and focusing means will now be described in greater detail.

The display 36 is of a type having inherent luminescence (such as LED or electroluminescent) or may be backlit (such as LCD). The level of backlighting or luminescence, as the case may be, must be sufficient to overcome transmission losses between the display and the eye, yet remain visible over background light. The perceived brightness of the display may be increased by providing the right lens 22 with a partially-reflective coating.

The display 36 may be alphanumeric or dot matrix, provided that it meets the functional requirements for the information to be displayed, although the ability of a dot matrix display to display graphics is to be preferred. The minimum acceptable display resolution is approximately 8 x 8 characters or 24 x 36 pixels, as the case may be.

A focusing lens 38 is mounted within the housing 26 close to its open end. The focusing lens 38 has a positive power, and serves to focus an image of the display at a point axially removed from the open end of the housing 26, the focal distance being determined by the distance between the focusing lens 38 and the display 36. In this embodiment, but as an optional feature of the invention, the distance between the focusing lens 38 and the display 36 may be manually adjusted by the wearer by manipulation of the outer end portion 28 of the housing 26, the focusing lens 38 and the outer end portion 28 being operatively coupled to enable such adjustment. The focusing lens 38 is shown at its furthest from the display 36 at 38' in Figure 5.

A reducing lens 40 of negative power may be disposed in the housing 26 between the display 36 and the focusing lens 38. The reducing lens is required only in those embodiments where the focused image of the display 38 would otherwise be too large when viewed by the wearer.

The focused image of the display 36 is projected from the housing 26 towards the right lens 22, as shown in Figure 2. Some of the light making up the focused image is reflected towards the right eye of the wearer. The wearer will thus see an image of the display 36 superimposed upon his or her view of the outside world through the lens. The image of the display will appear in focus when the wearer's eye focuses to a distance corresponding to the point to the front of the right lens 22 where the image is focused.

Re-focusing of the wearer's eyes may be minimised if the focal point of the image is adjusted to correspond with the distance at which most of the wearer's observation of the outside world is taking place.

In this embodiment, the display 36 is approximately 25.4 mm x 20 mm, the reducing lens 40 is 12 mm in diameter and has a focal length of -24 mm, and the focusing lens 38 is 12 mm in diameter and has a focal length of 60 mm. The reducing lens 40 is fixed at 38 mm from the display 36, and the focusing lens 38 is adjustable between 38 mm and 50 mm from the reducing lens 40. This arrangement gives a focus range of between 3 m and infinity.

In a first modification to the present embodiment, a beam splitter is provided between the focusing lens 38 and the right front lens 22 which transmits a first portion of the light forming the display image to the right front lens 22 and a second portion of that light in a direction such that it is visible when the mask 10 is hand-held. In an alternative modification, a second luminescent or illuminated display is provided, disposed such that it is visible when the mask is hand-held, the second display repeating the information displayed on the display 36.

An alternative optical arrangement for the display means is illustrated by Figure 6 in which a pair of prisms 70 and 72 are introduced adjacent to the focusing lens 38 in order to shift the central axis of the sightline.

In order to resist misting, to which the interior of a divers' mask is prone, the interior of the right and left lenses 20,22, the surfaces of the focusing and reducing lenses 38,40, and the surface of the display 36 are coated with a water and dirt repellant coating, for example that sold as Ritec (R.T.M.). This coating also helps clear the optical path from the display 36 to the wearer's eye following the clearing of water from a flooded mask.

In order for the display image to be visible in high ambient light levels (e.g. shallow dives in tropical countries) it may be desirable to provide a high contrast background to the reflected image. This can be achieved by constructing the front lens of the mask from a sandwich of BK7 tempered glass 74 and photochromic glass 76, with a semi-reflective coating on the inside face of the tempered glass. When high levels of ultra-violet light are present, for example at shallow depths, the glass will darken and so provide a high contrast background to the reflected image.

It will be appreciated that the invention is equally applicable to a mask having just one front lens for both left and right eyes, and that the display could be presented to the left eye instead of the right eye.

An electronic control unit 44 to control operation of the display 36 is mounted at a convenient location within the face mask 12. The control unit 44 and the display 36 are powered by a battery pack 46 mounted on the face mask 12 adjacent the left eye of the wearer.

Advantageously, the battery pack 46 and the housing 26 are of similar external dimensions such that these positions may be interchanged during manufacture so allowing the display image to be presented to the wearer's left eye.

A block diagram of the control unit 44 is shown in Figure 4.

The control unit 44 comprises a central processor 50 incorporating ROM and RAM, for example an 80c535 microcontroller. The central processor receives a clock signal from a clock 52. The central processor 50 communicates through I/O circuitry 54 with a switching module 56, the display 36 and a battery condition monitor 58. The central processor 50 also receives data from an external pressure sensor 60, the signal from the sensor 60 having first been processed at 62 and then digitised by an analogue to digital converter 64. The components of the control unit 44 are supplied with power from the battery pack 46 through a power supply 66. Operation of the central processor 50 is controlled by a software program.

The pressure sensor 60 is preferably mounted on the same circuit board as the control unit. A piezoresistive miniature ceramic substrate silicon sensor is suitable, having a range of 0-Il bar, a linearity of 0.1% FSO and an accuracy of 0.01 bar. A port connecting the sensor 60 to the mask's surroundings is provided, a seal being made between the port and the sensor to ensure that the other components on the circuit board are isolated from water in the port.

The switching module 56 is connected to three electrodes on an outer surface of the mask 10, the switching module 56 being operative to detect submersion of the mask 10 through a conductive path being established between the electrodes.

Optionally, an ambient light sensor may be provided which detects the level of ambient light in which the diver is operating and feeds a signal representative of the light level to the central processor 50. The central processor 50 modifies the perceived brightness of the display 36 accordingly such that it is bright when the ambient light level is high and less bright when the ambient light level is low.

The central processor 50 may vary the brightness by pulse-width modulation of the signal applied to the display or its backlight, as the case may be.

The data displayed by the display means is comparable to that available from a conventional dive computer, and will typically include: Current depth Maximum depth Time down Surface Interval Dive log No fly time Battery low The Buhlmann dive tables are to be used for the calculation of all No stop and No fly times.

A decompression algorithm may also be included.

In any given mask, several display features may be omitted such that a range of masks of varying degrees of complexity may be provided.

In operation display means has a standby mode, underwater mode and surface mode. It switches between these modes automatically under the following conditions: a) Standby mode The system is in standby mode when it is not in either of the other modes. In this mode, the system continues to monitor the pressure and the presence of moisture between three electrodes. In this mode the display and backlighting and other non-critical components are switched off to conserve battery power.

The system is in standby mode when delivered and enters standby mode automatically when the estimate of residual nitrogen drops to zero after a dive and or the no fly time drops to zero and/or 1 minute after the last surface mode usage.

b) Underwater mode The system enters underwater mode automatically when water is sensed between all three electrodes (ie.

when the system is in the water). The timer is not activated until the system is at a depth of 0.5m. The timer stops if the diver rises above 0.5m but is not reset unless the system enters resurface mode.

In underwater mode, the system display current depth in metres, maximum depth in meters, dive time in minutes and preferably the no-stop time remaining although this may need to be cycled with the other information. The system will constantly monitor the diver's ascent and descent rate. A visual warning will be given if the ascent rate is greater than 10 metres/minute.

c) Surface mode The system enters surface mode automatically 5 minutes after the diver leaves the water. When the unit enters surface mode the previous dive details are logged into the system's memory and the system will display the surface interval time in minutes.

It shall be possible to enter surface mode from standby mode manually by touching two of the electrodes with wet fingers. In surface mode it shall be possible to view the following information by pressing the electrodes in different combinations: Dive memory showing information from the previous 10 dives.

Estimated time before the residual nitrogen in the tissues drops to zero (From look-up tables).

Estimated No Fly time (From look-up tables).

d) The Battery condition shall be monitored in surface and underwater modes and battery-low symbol shall be displayed if the algorithm determines that the battery condition has dropped below a predetermined threshold.

The surface information may be displayed on a separate surface LCD display located at the rear of the lens housing. This information will only be needed on the surface following a dive when the diver will have removed the mask. The diver can interrogate the display without having to put the mask on.

Claims

1. A diver's mask having display means operative to generate a data display visible to a diver wearing the mask, wherein there is provided focusing means arranged to cause the image of the data display to appear to be focused to the front of the diver beyond the mask.

2. A mask according to claim 1 in which the focusing means is adjustable to vary the distance in front of the diver at which the image appears to be focused.

3. A mask according to any of the preceding claims in which the focusing means comprises means whereby the image size can be varied.

4. A mask according to any one of the preceding claims in which the focusing means is arranged to direct the image towards a front lens of the mask, the diver viewing a reflection from the front lens.

5. A mask according to claim 4 in which the front lens is semi-reflective to enhance reflection of the image.

6. A mask according to any one of the preceding claims in which the display means is integrated into the mask.

7. A mask according to claim 6 in which the display means is housed adjacent to one side of the mask.

8. A mask according to claim 7 in which the display means and a battery pack there for are mounted on opposite sides of the mask, so as to be disposed on opposite sides of the wearer's head.

9. A diver's mask substantially as hereinbefore described with reference either to Figures 1 to 5 of the drawings, or to Figures 1, 2, 3, 4 and 6 of the drawings.

10. A divers' mask having display means operative to display information visible to a diver wearing the mask, in which the display means is integrated into the mask.