EP1404266A1

EP1404266A1 - A device for minimising glare

Info

Publication number: EP1404266A1
Application number: EP02743586A
Authority: EP
Inventors: Donal O'keeffe; Albert O'halloran
Original assignee: Vlyte Innovations Ltd
Current assignee: Vlyte Innovations Ltd
Priority date: 2001-07-11
Filing date: 2002-07-11
Publication date: 2004-04-07
Also published as: WO2003005942A1

Abstract

Spectacles (1) for use by a driver of a vehicle for minimisign glare from the headlights of an oncoming vehicle comprises a frame (2) with lenses (4) which are formed by panels (5) having an electro-optical medium (20) laminated therein. The panels (5) of the lenses (4) define respective bands (32) of pixels (26) which are selectively operable in a hight transmitting mode and a light attenuating mode. A CMOS camera (40) monitors the brightness of light in the field of view of a subject, and on the brightness in any region of the field of view exceeding a predetermined level the pixel or pixels (26) in the respective bands (32) corresponding to the region in which the brightness of the light exceeds the predetermined level are operated for attenuating the light in that location for in turn minimising glare from the light source.

Description

"A device for minimising glare"

The present invention relates to a device for minimising glare from a light source, and in particular, though not limited to a device for wearing by a subject adjacent the eyes for minimising glare from, for example, headlights of an oncoming car, the setting or rising sun, or the like.

Night driving or driving in a direction towards the setting or rising sun can be hazardous. Oncoming car headlights or the rising or setting sun cause significant glare which reduces the drivers ability to see objects in the near ground, for example, pedestrians, road signs and the like. In order to minimise the affect of glare it is known to provide glasses with light sensitive lenses whereby the lenses on being subjected to bright incident light tend to tint, thereby, to some extent, reducing the glare. However, a problem with such glasses is that the entire area of each of the lens tends to tint, and while the tinting of the lenses reduces the glare, unfortunately the tinting of the lenses also reduces the ability of a driver to see objects in the near ground. Additionally, the recovery time of such tinted lens is relatively slow, and a driver may have little or no visibility through the lens for some time after the source of bright light has passed or otherwise is no longer incident on the lenses, until the lenses have recovered to their untinted state. This is undesirable.

There is therefore a need for a device for reducing glare from a light source which overcomes this problem. The present invention is directed towards providing such a device.

According to the invention there is provided a device for minimising glare from a light source wherein the device comprises a panel defining a lens area for placing in the field of view of a subject of one eye thereof, the panel comprising an electro-optical medium defining at least one pixel in the lens area, the pixel being selectively and alternately operable in a light transmitting mode for accommodating light substantially unimpeded therethrough, and in a light attenuating mode for attenuating light passing therethrough, a monitoring means for monitoring the level of light in the field of view of the subject, and a control means responsive to the monitoring means for selectively operating at least one of the pixels in a light attenuating mode at a location in the lens area corresponding to a region in the field of view in which the level of incident light is determined as exceeding a predetermined light level for minimising glare from the light source.

In one embodiment of the invention the control means comprises a computing means responsive to the monitoring means for computing the average level of light in the field of view, and the predetermined level of light at which the control means is responsive for operating the pixels in the light attenuating mode is a predetermined light level above the computed average level of light.

In another embodiment of the invention each pixel is operable at one level of attenuation in the light attenuating mode. In a further embodiment of the invention each pixel is operable at a plurality of levels of attenuation in the light attenuating mode.

In a still further embodiment of the invention the level of attenuation at which each pixel to be operated in the light attenuating mode is a function of the amount by which the light incident in the corresponding region of the field of view exceeds the predetermined light level.

In one embodiment of the invention the panel defines a pair of lens areas for placing adjacent the respective eyes of the subject in the field of view thereof.

In another embodiment of the invention a pair of panels are provided, each panel defining a lens area for placing adjacent the corresponding one of the eyes of the subject in the field of view thereof. Preferably, the pixels in corresponding locations of the respective lens areas are operated by the control means at respective different levels of attenuation in response to the level of light in a corresponding region exceeding the predetermined light level.

In one embodiment of the invention the control means operates the pixels in locations in the respective lens areas corresponding to a region in the field of view in which the incident light exceeds the predetermined light level, such that the level of attenuation at which each pixel to be attenuated at the location in one of the lens areas is greater than the level of attenuation at which each pixel in the corresponding location of the other lens area is operated.

Preferably, each pixel in the location in one of the lens areas in which each pixel is operated at the greater level of attenuation is operated at a level of attenuation in the range of 40% to 95%, and each pixel in the corresponding location in the other one of the lens areas is operated at a level of attenuation in the range of 0% to 60%.

Advantageously, each pixel in the location in one of the lens areas in which each pixel is operated at the greater level of attenuation is operated at a level of attenuation in the range of 50% to 95%, and each pixel in the corresponding location in the other one of the lens areas is operated at a level of attenuation in the range of 10% to 55%.

Preferably, each pixel in the location in one of the lens areas in which each pixel is operated at the greater level of attenuation is operated at a level of attenuation in the range of 65% to 85%, and each pixel in the corresponding location in the other one of the lens areas is operated at a level of attenuation in the range of 40% to 55%.

Ideally, each pixel in the location in one of the lens areas in which each pixel is operated at the greater level of attenuation is operated at a level of attenuation of approximately 75%, and each pixel in the corresponding location in the other one of the lens areas is operated at a level of attenuation of approximately 50%.

In one embodiment of the invention the lens area in which the pixels are operated at the greater level of attenuation corresponds to the right-hand eye of the subject. Alternatively, the lens area in which the pixels are operated at the greater level of attenuation corresponds to the left-hand eye of the subject.

Preferably, a plurality of pixels are provided in each lens area. Advantageously, the pixels in each lens area are arranged to form a band extending transversely across each lens area from one of the left and right-hand sides thereof.

In one embodiment of the invention the band of pixels is located in each lens area to be above the normal line of sight of the subject. Preferably, the band of pixels in each lens area extends from the one of the left and right-hand sides of the lens area towards the other side thereof. Advantageously, the band of pixels in each lens areas terminates intermediate the centre of the corresponding lens area and the side towards which the band is extending.

In one embodiment of the invention a greater number of pixels are provided in each lens area towards the one of the left and right-hand sides from which the corresponding band of pixels extends.

In another embodiment of the invention at least one pixel is provided extending downwardly from the band of pixels in each lens area adjacent the one of the left and right-hand sides from which the corresponding band of pixels extend.

In another embodiment of the invention the band of pixels in each lens area extends from the left-hand side thereof. Alternatively, the band of pixels in each lens area extends from the right-hand side thereof.

In one embodiment of the invention each pixel in the band of pixels in each lens area extends the width of the band.

Preferably, each pixel in each lens area is operable in the light attenuating mode on being powered up, and is operable in the light transmitting mode on being powered down.

In one embodiment of the invention the electro-optical medium of each panel is a cholesteric liquid crystal medium.

In another embodiment of the invention each panel comprises a first substrate and a second substrate, and the electro-optical medium is sandwiched between the respective substrates. Preferably, a single electrode is provided on one of the first and second substrates adjacent the electro-optical medium, and a plurality of pixel defining electrodes are provided on the other of the first and second substrates for co-operating with the single electrode for defining the respective pixels in the corresponding lens area. Advantageously, a plurality of electrically conductive tracks are provided on the substrate carrying the plurality of electrodes for addressing the respective electrodes, and an area of the other of the first and second substrate on which the single electrode is formed is provided free of electrode , the area free of electrode corresponding to the addressing tracks for preventing the addressing tracks co-operating with the single electrode for defining unwanted pixels.

In one embodiment of the invention the control means is responsive to the level of brightness of the light incident in a region of the field of view exceeding a predetermined light brightness level for operating the at least one of the pixels in the light attenuating mode.

Preferably, the monitoring means is located intermediate the lens areas.

In one embodiment of the invention the device comprises spectacles having a pair of lens receiving portions, and one of the panels defining the lens area being located in each lens receiving portion. Advantageously, the monitoring means is provided on a bridge piece of the spectacles extending between the respective lens receiving portions

Alternatively, the device comprises a visor. In one embodiment of the invention the visor comprises a pair of lens receiving portions, and one of the panels defining the lens area being located in each lens receiving portion. Alternatively, the visor comprises a panel receiving portion, and the panel which defines respective lens areas being located in the panel receiving portion. Preferably, the monitoring means is provided intermediate the respective lens areas.

In one embodiment of the invention the device is suitable for wearing by a driver driving on the right hand side of the road, and the band of pixels in each lens area extends from the left hand side of each lens area. Alternatively, the device is suitable for wearing by a driver driving on the left hand side of the road, and the band of pixels in each lens area extends from the right hand side of the lens area.

In one embodiment of the invention the pixels in the lens area corresponding to the right hand eye of the subject to be operated in the attenuating mode are operated at the greater level of attenuation.

In another embodiment of the invention the control means comprises drivers for driving the respective pixels in each lens area.

In a further embodiment of the invention the monitoring means comprises a camera. Advantageously, the camera is a CMOS camera.

Additionally the invention provides a method for minimising glare from a light source, wherein the method comprises the steps of placing a panel defining a lens area in the field of view of a subject with the lens area in the field of view of one eye thereof, the panel comprising an electro-optical medium defining at least one pixel in the lens area, the pixel being selectively and alternately operable in a light transmitting mode for accommodating light substantially unimpeded therethrough, and in a light attenuating mode for attenuating light passing therethrough, monitoring the level of light in the field of view of the subject, determining if the level of light exceeds a predetermined light level, and in response to the level of light incident in a region in the field of view of the subject exceeding the predetermined light level operating at least one of the pixels in a location of the lens area corresponding to the region in the field of view in which the level of light exceeds the predetermined light level in the light attenuating mode for attenuating the light at the location for minimising glare from the light source.

In one embodiment of the invention the average level of light in the field of view of the subject is computed, and on the level of light incident in a region of the field of view being above the computed average light level by a predetermined light level, one pixel in a location of the lens area which corresponds to the region in which the level of light exceeds the predetermined light level is operated in the light attenuating mode.

In one embodiment of the invention each pixel in the location corresponding to the region of the field of view in which the level of light exceeds the predetermined light level is operated in the light attenuating mode.

In another embodiment of the invention each pixel is operated in the light attenuating mode at a level of attenuation which is a function of the amount by which the light level in the corresponding region of the field of view exceeds the predetermined light level.

In one embodiment of the invention the panel defines two lens areas, and the panel is placed in the field of view with the respective lens areas adjacent the corresponding eyes of the subject.

Alternatively, a pair of panels each defining one lens area are placed in the field of view of the subject adjacent the corresponding eyes of the subject.

In another embodiment of the invention each pixel in the location of one of the lens areas corresponding to the region in the field of view in which the light level exceeds the predetermined light level is operated at a greater level of attenuation than each pixel in the corresponding location of the other lens area.

In another embodiment of the invention each pixel in the location in one of the lens areas in which each pixel is operated at the greater level of attenuation is operated at a level of attenuation in the range of 40% to 95%, and each pixel in the corresponding location in the other one of the lens areas is operated at a level of attenuation in the range of 0% to 60%.

The advantages of the invention are many. The most important advantage of the invention is that by virtue of the fact that glare is minimised, a subject retains vision even in the presence of a bright light source directed at the eyes of a subject, and objects in the near field remain visible. This is a particularly important advantage to a driver driving a road, or other vehicle where the driver is subjected to oncoming lights of another vehicle, or the rising or setting sun. By virtue of the fact that glare is minimised, objects in the driver's path remain visible, which would otherwise not be visible due to glare, for example, a pedestrian on the side of the road, a road sign or the like remain visible. A particularly important advantage of the invention is achieved when the pixels at the locations in the respective lens areas corresponding to a region in the field of view in which the incident light exceeds the predetermined light level are operated in the attenuating mode at different attenuating levels in the respective lens areas. By virtue of the phenomenon of binocular vision the brain of the driver on receiving respective images of an object from the respective eyes fuses the respective images into a single image, and although the image of the object from one of the eyes is considerably weaker than the image from the other eye due to the different levels of attenuation at which the pixels in the respective lens are operated, the weaker image of the object is effectively enhanced by the brain, thus ensuring that the object is visible. Binocular vision is a phenomenon whereby the brain selects and enhances the dominant of two images received from the respective eyes, and will be well known to those skilled in the art. Needless to say, the device according to the invention has many other advantages, in that by virtue of the fact that glare is minimised from a bright light source, a person using the device is provided with continuing visibility in the direction from which light from the light source eminates.

Needless to say, where the device is to minimise glare from an oncoming light source which is directly in front of a subject, the pixels will be appropriately arranged in the lens, and for example, in the embodiment of the invention where the pixels are provided in a band extending from one side of each lens area, it is envisaged that the band may extend completely across the lens area from one side to the other, and this, would thus permit the appropriate pixel or pixels to be operated in the light attenuating mode for attenuating glare from oncoming light from dead ahead, or either side of dead ahead. This, would be particularly suitable for minimising glare from the rising or setting sun.

The invention will be more clearly understood from the following description of a preferred embodiment thereof which is given by way of example only with reference to the accompanying drawings, in which:

Fig. 1 is a perspective view of a device according to the invention,

Fig. 2 is a transverse cross-sectional side elevational view of a portion of the device of Fig. 1 on the line II - II of Fig. 1 ,

Fig. 3 is a perspective view of the device of Fig. 1 in use,

Fig.4 is a circuit diagram of the device of Fig. 1 ,

Fig. 5 is a perspective view of a portion of the device of Fig. 1 ,

Fig. 6 is a perspective view of another portion of the device of Fig. 1 , and

Fig. 7 is a graphical representation of the operation of the device of Fig. 1. Referring to the drawings there is illustrated a device according to the invention which in this case is provided in the form of spectacles, indicated generally by the reference numeral 1 , which are suitable for wearing by a driver of a car or other vehicle for minimising glare from a light source, for example, the headlights of an oncoming car, or the setting or rising sun. Indeed, the spectacles are suitable for minimising glare from any other source of bright light which may cause glare and reduce a drivers ability to see objects in the near ground. The spectacles 1 are particularly suitable for night driving, and in this embodiment of the invention are provided for a driver who would be driving on the right hand side of the road. The spectacles 1 comprise a conventional spectacles frame 2 forming two lens receiving portions 3. A pair of panels 5a and 5b which define lens areas and form lenses 4a and 4b, respectively, are located in the lens receiving portions 3, and are operable for minimising glare as will be described below. The lens 4a formed by the panel 5a is the left hand lens when view from the rear, and is thus the lens which in use is located adjacent the left eye of the driver, and the lens 4b formed by the panel 5b is the right hand lens. The lens receiving portions 3 are joined by a bridge piece 6, which in use extends across the nose of a wearer. A pair of shafts 7 extend rearwardly from the sides of the lens receiving portions 3 for engaging the ears of a wearer.

Each panel 5 which forms a corresponding lens 4 comprises a laminate constructed from a pair of outer laminates of transparent polycarbonate material, namely, a front outer laminate 9 and a rear outer laminate 10. A first substrate, namely, a front substrate 11 and a second substrate, namely, a rear substrate 12, both of transparent PET material are located between the front and rear outer laminates 9 and 10. The rear substrate 12 is laminated to the rear outer laminate 10 and is bonded thereto by a suitable transparent optical adhesive. The front substrate 11 is laminated to a light control film 15, which in turn is laminated to the front outer laminate 9. The light control film 15 is bonded to the front substrate 11 and the front outer laminate 9 by a suitable transparent optical adhesive. The light control film 15 is a transparent film of PET material, and an upper portion 16 of the light control film 15 towards a top edge 17 of each lens 4 is tinted for minimising glare from sunlight which would normally be experienced during normal daytime driving, should the spectacles also be used for daytime driving.

An electro-optical medium 20, which in this embodiment of the invention is provided by a cholesteric liquid crystal medium is sandwiched between the front and rear substrates 11 and 12. The electro-optical medium 20 is not bonded to the front and rear substrates 11 and 12, however, a sealing band 22 extends around the peripheral edge of each panel 5 for retaining the laminates of the front and rear outer laminates 9 and 10, the front and rear substrates 11 and 12, the light control film 15 and the electro-optical medium 20 laminated together.

Inner surfaces 23 of the respective front and rear substrates 11 and 12 adjacent to the electro-optical medium 20 are coated with an electrically conductive transparent coating of indium tin oxide, which is patterned to form electrodes 24 and 25, respectively, for co-operating with the electro-optical medium 20 for defining a plurality of individually selectively addressable pixels 26 and 27. The inner surface 23 of the rear substrate 12 is patterned to form one large single electrode 25, while the inner surface 23 of the front substrate 1 is patterned to form a plurality of column electrodes 24, which co-operate with the electrode 25 to define the pixels 26 and 27. Electrically conductive addressing tracks 30, only four of which are illustrated in Fig. 5 are also patterned on the inner surface 23 of the front substrate 1 for facilitating individual addressing of the electrodes 24. An area 31 of the inner surface 23 of the rear substrate 12 is provided free of the electrode 25, and this area 31 coincides with the addressing tracks 30 thereby avoiding the formation of pixels by the tracks 30.

The cholesteric liquid crystal medium is of the type which on the electrodes 24 and 25 defining each pixel 26 or 27 being powered up the pixel operates in a light attenuating mode for attenuating light passing therethrough, and on being powered down operates in a light transmitting mode for accommodating light substantially unimpeded passing therethrough. Accordingly, in the absence of power the lenses 4 formed by the panels 5 fail safe to the light transmitting mode, and are thus transparent in the absence of power. The level of light attenuation imposed on light passing through each pixel is a function of the voltage applied across the pixel by the electrodes 24 and 25, as will be described below with reference to Fig. 7.

The electrodes 24 and 25 are arranged to form the pixels 26 in each panel 5 in the form of a band 32 which extends from the left hand side 33 of the respective panels 5 when viewed from the rear transversely across the panels 5. Each band 32 of pixels 26 terminates at 35 intermediate the centre of the corresponding panel 5 and its right hand side 37. The pixels 26 each extend the width w of the bands 32, and the electrodes 24 defining the pixels 26 are individually addressed through the tracks 30. The two pixels 27 are located towards the left hand side of the respective panels 5 when viewed from the rear, and extend downwardly from the corresponding band 32, and the electrodes 24 defining the pixels 27 are addressed from the adjacent edge of the panel 5. Since the band of pixels 26 and the pixels 27 are located towards the left hand side of the spectacles 1 when viewed from the rear the spectacles 1 are particularly suitable for night driving by a driver driving on the right hand side of the road. The bands 32 are located in the field of view of the driver in which the headlights of an oncoming vehicle would normally appear to the driver. The pixels 26 are of relatively large area, and the width w of the bands of pixels 26 is such as to be wider than the width, top to bottom, of the area in the field of view of a driver in which headlights of an oncoming vehicle would normally appear. Additionally, the two pixels 27 are located to the left hand side 33 of the panels 5 in areas where the headlights of an oncoming vehicle would normally appear as the oncoming vehicle is closely approaching and passing by the driver.

The electrodes 24 and 25 defining the pixels 26 and 27 are selectively addressable by a control circuit 39, described in detail below with reference to Fig. 4 for operating the pixels 26 and 27 alternately in the light attenuating mode and in the light transmitting mode.

A monitoring means, namely, a CMOS camera 40 mounted on the bridge piece 6 of the spectacles 1 monitors incident light thereon for determining the level of light in the field of view of the subject to which the respective eyes of the subject are subjected. The CMOS camera 40 is of the type which comprises a pixelated area (not shown) defining a plurality of light sensitive pixels (also not shown), which correspond to respective regions in the field of view of the driver. Such CMOS cameras will be well known to those skilled in the art. The control circuit 39 comprises a micro-controller 42 which reads signals from the respective pixels (not shown) of the pixelated area of the CMOS camera 40 for determining the level of brightness of incident light in regions of the field of view of the driver corresponding to the pixels (not shown) of the pixelated area (also not shown). The micro-controller 42 computes the average brightness level of the light incident in the field of view of the driver from the signals from the pixelated area (not shown) of the CMOS camera 40, and compares the brightness level of the incident light on each of the pixels (not shown) of the pixelated area (not shown) with the computed average brightness level. On the brightness level of the incident light on any of the pixels (not shown) in the pixelated area, which correspond with regions in the field of view coinciding with the pixels 26 or 27 of the panels 5, exceeding a predetermined brightness level above the average computed brightness level, the control circuit 39 in response to the micro-controller 42 operates the corresponding pixels 26 or 27 in the light attenuating mode for attenuating the light through the selected pixels 26 or 27, for in turn minimising glare from the light source.

The predetermined brightness level by which the incident light should exceed the average brightness level before the corresponding pixels 26 and/or 27 are operated in the light attenuating mode may be set at any suitable predetermined amount, and typically, would be two or three times the average brightness level. Such excessive brightness levels in a local region would be typically be caused by the headlights of an oncoming car or the setting or rising of the sun.

Because the eyes of the driver are unable to focus on the pixels 26 and 27, because of their closeness to the eye, and the area of the pixels 26 are relatively large, in general, it is sufficient to operate one or two of the pixels 26 or 27 which are side by side in the light attenuating mode in the location which corresponds with the region in the field of view where light of brightness which exceeds the predetermined brightness level has been detected, see Fig. 3, where only one pixel 26 in each panel 5 is illustrated as being operated in the light attenuating mode. This, thus, minimises the area in the field of view of the driver in which incident light is attenuated, thereby in turn minimising loss of visibility in the remaining portions of the field of view of the driver.

Driver circuits 43 and 44, see Fig. 4, are operated under the control of the microcontroller 42 for powering the selected one or ones of the pixels 26 and/or 27 in the panels 5. The driver circuit 43 is a left hand driver circuit for powering the electrodes 24 and 25 for selectively operating the pixels 26 and 27 in the left hand panel 5a when viewed from the rear in the light attenuating mode. The driver circuit 44 is a right hand driver circuit for powering the electrodes 24 and 25 for selectively operating the pixels 26 and 27 in the right hand panel 5b in the light attenuating mode. A battery 45 powers the control circuit 39, the driver circuits 43 and 44, the micro-controller 42 and the CMOS camera 40. In this embodiment of the invention the driver circuits 43 and 44 are operable under the control of the micro-controller 42 for applying different voltage levels to the electrodes 24 and 25 of the respective left and right hand panels 5a and 5b for operating the selected pixels 26 and/or 27 in the respective panels 5a and 5b in the light attenuating mode at different light attenuating levels. The pixels 26 and 27 in the right hand panel 5b are operated at a greater level of light attenuation than the corresponding pixels in the left hand panel 5a, see Fig. 3. In this embodiment of the invention the pixels 26 and 27 in the right hand panel 5b are operated at an attenuation level of approximately 75%, while the pixels 26 and 27 in the left hand panel 5a are operated at an attenuation level of approximately 50%. In other words only 25% of light passes through the pixels 26 and/or 27 which are operating in the light attenuating mode in the right hand panel 5b, while 50% of the passes through the pixels 26 and/or 27 operating in the light attenuating mode in the left hand panel 5a.

Binocular vision of the driver thus causes the brain of the driver to fuse the two distinct images received from his or her respective eyes into a single image. The phenomenon of binocular vision which will be well known to those skilled in the art has the effect that the driver sees the image from the eye which receives the greater amount of light, in other words, the left eye which receives the 50% attenuated light as the predominant image, unless oncoming lights are so strong as to be outside the comfortable adaptation of the eye at the time, in which case, the image from the eye which receives the 75% attenuated light, namely, the right eye is predominantly seen. Accordingly, regardless of the strength of the oncoming light visibility is always maintained, thus providing safety and comfort for the driver in all driving conditions.

The control circuit 39, the micro-controller 42 and the driver circuits 43 and 44 are located in a controller housing 48 to one side of the frame 2. A battery housing 50 to the other side of the frame 2 houses the battery 45 for powering the control circuit 39. A switch 49 is provided in the housing 50 for isolating the control circuit 39 from the battery 45. Electrically conductive wires (not shown) are carried through the frame 2 between the battery 45 and the control circuit 39 and the CMOS camera 40 for providing electrical communication between the battery 45, the control circuit 39 and the CMOS camera 40. Additionally, electrically conductive wires (not shown) are provided in the frame 2 between the driver circuits 43 and 44 and the electrode 25 of the rear substrate 12 and the electrically conductive tracks 30 on the front substrate 11 for facilitating addressing the electrodes 24 and 25.

Referring now to Fig. 7 a curve of specular light transmission through the pixels 26 and 27 plotted against root mean square voltage applied to their corresponding electrodes is illustrated. As the voltage applied to the pixels 26 and 27 by the electrodes 24 and 25 increases the level of attenuation likewise increases from 100%, in other words, where all light incident on the panels 5 is permitted to pass through the pixels 26 and 27 to an attenuation level of approximately 0% where the pixels 26 and 27 effectively act to block incident light passing through the pixels 26 and 27. As discussed above in this embodiment of the invention the output voltage of the right hand driver circuit 44 is set at a higher voltage than the output voltage of the left hand driver 43 so that the level of attenuation provided by the pixels 26 and 27 in the right hand panel 5b is greater than the level of attenuation provided by the corresponding pixels 26 and 27 in the left hand panel 5a.

In use, with the spectacles 1 fitted to the driver and the power from the battery 45 switched by the switch 49 to power up the control circuit 39, the CMOS camera 40 the micro-controller 42 and the driver circuits 43 and 44, the spectacles 1 are ready for use. The micro-controller 42 in the control circuit 39 reads the outputs from the respective pixels (not shown) of the pixelated area (not shown) of the CMOS camera 40 for determining the brightness level of light incident on each of the pixels (not shown) of the pixelated area (not shown). The micro-controller 42 computes the average brightness level of light incident on the pixelated area, which is equivalent to the field of view of the driver. The micro-controller 42 compares the level of brightness incident one each of the pixels (not shown) of the pixelated area (not shown) of the CMOS camera 40 with the computed average brightness. For so long as the respective brightness levels remain below the predetermined value of brightness level above the computed average brightness level, no action is taken.

As soon as the brightness level in a region in the field of view of the driver corresponding to a location at which the pixels 26 and 27 are located exceeds the predetermined brightness level, the control circuit 39 under the control of the microcontroller 42 operates the driver circuits 43 and 44 for operating the pixel or pixels 26 and/or 27 in the location in the panels 5 corresponding to the region in the field of view in which the brightness level exceeds the predetermined brightness level in the light attenuating mode for attenuating the light in the location in the respective panels 5. The pixel or pixels 26 or 27 which are operated in the light attenuating mode in the left hand panel 5a are operated to attenuate the light at an attenuation level of 50%, while the pixel or pixels in the right hand panel 5b are operated to attenuate the light at a level of 75%.

Additionally, if the source of excessive bright light is the headlights of an oncoming vehicle, as the oncoming vehicle approaches, the region in the field of view of the driver in which the incident light from the headlights appears moves transversely across the field of view along the respective bands 32 of pixels 26 from the end 35 to the left hand side 33. Accordingly, the pixels 26 in the bands 32 are sequentially operated from the ends 35 to the left hand side 33 in the light attenuating mode to follow the path of the headlights as it traverses the field of view from left to right of the driver.

By providing the pixels 26 in the form of a band and in a location in the field of view of the driver where headlights of an oncoming vehicle normally appear, and likewise by providing the pixels 27 towards the left hand side 37 also where the headlights of an oncoming vehicle appear, areas where objects and traffic lights would normally appear in the field of view of the driver are visible once light from the oncoming vehicle has been attenuated. For example, for drivers driving on the right hand side of the road, pedestrians normally are visible towards the right hand side in the field of view, while car tail lights are typically viewed through respective lower areas of the lenses below the bands 32 of pixels 26. Traffic lights and street lights and the like are typically viewed through upper areas of the respective panels 5 which are above the bands 32 of the pixels 26. Thus, by only defining pixels 26 in the bands 32 and the two pixels 27 on the left hand sides of the lenses 4 substantially 100% of the light incident on the remaining areas of the lenses 4 pass through the lenses in these areas and thus guarantee visibility to the subject at all times of objects appearing in regions in the field of view of the driver corresponding to these areas. Additionally, light from the headlights from a following vehicle reflected from a driving door side mirror of the vehicle typically appears in the regions of the field of view corresponding to the pixels 27 in the respective panels 5, and thus, by operating the pixels 27 in a light attenuating mode light glare from the headlights of following vehicles is minimised.

It is envisaged that the spectacles according to the invention may be provided as dual functioning spectacles, providing for both day and night time use. During the daytime, it is envisaged that the micro-controller would be programmed for operating the left and right hand drivers to in turn operate the pixels 26 and 27 in the respective left and right hand panels 5a and 5b with similar levels of attenuation. Such level of attenuation would typically be in the range of 40% to 75%. However, during night time the micro-controller would be programmed to operate the left and right hand drivers as already described whereby the pixels 26 and 27 in the right hand panel 5b are attenuated at a greater level of attenuation than those in the left hand panel 5a. Alternatively, the control circuit may be programmed for operating only one of the left and right hand drivers for operating the pixels in the corresponding left hand or right hand panel for attenuating light passing through one of the panels 5a or 5b only. It is believed that a high level of light attenuation, for example, 90% in one of the panels 5, and little or no attenuation in the other panel 5 would be particularly useful at sunset, when a driver is driving into the sun. The light control film 15 would combine with the pixels 26 to attenuate the light from a setting sun sufficiently to minimise glare. In this case, the driver could tilt his or her head slightly forward to view the scene ahead through the top portion of the panels, namely, through the bands 32 of pixels 26 and that portion of the panels above the bands 32, where the film 15 is tinted to provided greater attenuation. It is envisaged that it may be necessary to provide pixels 26 in the top portion of the panels 5 between the bands 32 and the top edge 17 of the panels 5 for daytime use, but generally, not for night time use.

In general, during the daytime, brightness levels are sufficiently high across the entire field of view of a driver that one level of light attenuation applied to the pixels 26 and 27 should be sufficient for safe use. However, for daytime use it is envisaged that the entire area of the panels 5 would be provided with selectably operable pixels, which could be operated during daytime use for attenuating all light in the field of view of the driver. As the light reduces in the evening below a threshold value the spectacles under the control of the control circuit 39 would automatically revert to night time driving mode whereby only the pixels 26 and 27 would be operable in the light attenuating mode. It is desirable that the light control film should not attenuate light in any area of the panels through which a driver would normally view the road ahead, namely, the area below the bands 32 of pixels 26 of each panel. Preferably, the light control film is tinted in the area above the band of pixels.

In order to protect the electro-optical medium 20, an ultra-violet filter may be required, and this could be provided by the light control film, if the light control film were provided as an ultra-violet light filter. In cases where the front and rear outer laminates are of polycarbonate which is a natural UV filter, a separate UV filter would not be required.

By providing the front and rear outer laminates as polycarbonate material, a further advantage of the invention is achieved in that the lenses are effectively shatterproof.

While the electro-optical medium has been described as being provided by a cholesteric liquid crystal medium, any other suitable electro-optical medium may be used. However, it is important that when selecting the electro-optical medium that the electro-optical medium should fail safe into the transparent light transmitting mode. Other suitable electro-optical medium which may be used are suspended particle device (SPD) medium, electro-chromic medium, and polymer dispersed liquid crystal (PDLC) medium.

While the front and rear outer laminates have been described as being of PET material, they may be of any other material, for example, glass or the like. It is also envisaged in certain cases that the light control film may be dispensed with, particularly, in cases where the spectacles are provided specifically for night time driving only.

While the device according to the invention has been described as being implemented as spectacles, it will be readily apparent to those skilled in the art that the device may be implemented in any other suitable form, for example, as a visor for clipping onto spectacles worn by a driver, and where the device is implemented as a visor, a pair of panels may be provided to form the respective lens, or a single panel may be provided which would define the two lens. It is also envisaged that where the device is provided in the form of a visor, it may be provided for securing or mounting to any other article besides spectacles, for example, a helmet of a motorcyclist, or the visor may be provided as a visor for securing in the vehicle adjacent the windscreen thereof.

While the device has been described for use by a driver of a motor vehicle, the device according to the invention may be used by any other person, whether a driver or otherwise.

While each panel has been described as comprising a band of pixels, and two side pixels, it is envisaged that in certain cases as discussed above, particularly, when the device is being used for daytime driving, the entire area of each panel may be provided with pixels. In order that the pixels would be individually addressable, it would be necessary to pattern both the front and rear substrates with electrodes, one of the front and rear substrates being patterned with column electrodes, while the other would be patterned with row electrodes. Such arrangements of electrodes for providing for individual addressing of pixels will be well known to those skilled in the art. Needless to say, while the pixels 26 in the band of pixels in each panel have been described as being the width of the band, the pixels may be of any suitable size. Indeed, it is envisaged where the pixels are provided as being of width similar to the width of the band, the pixels may be addressed from their respective opposite sides by electrically conductive tracks. This would have the advantage that if one of the electrically conductive tracks failed, the pixel would still be addressable through the other track. It is also envisaged that the two electrodes forming the side pixels 27 in each panel may be omitted, or if desired more side electrodes of different sizes may be provided.

Needless to say, it will be appreciated by those skilled in the art that if the spectacles were being provided for a driver driving on the left hand side of the road, the band of pixels of each panel would extend from the right hand edge of the panel, and if side pixels were provided, they would be located on the right hand side of the panels.

While the spectacles have been described as comprising two lenses, each formed by the panels, it is envisaged that the spectacles may be provided with only one of the lens being provided by a panel comprising an electro-optical medium, and the other lens would be provided by plain glass or plastics material. In which case, light would only be attenuated to one of the eyes of the subject. As discussed above in certain circumstances, attenuating light to one eye only, particularly, where the level of attenuation is relatively high, has certain advantages, and such advantages, in particular, arise where a driver is driving into the setting or rising sun.

While the panels have been described as being operated at respective fixed specific levels of attenuation, it will be readily apparent to those skilled in the art that the panels may be operated with other levels of attenuation. It is also envisaged that while it is preferable to operate the panels at respective different levels of attenuation, in certain cases the panels may each be operated at the same level of attenuation.

It is further envisaged that the levels of attenuation at which the panels are operable may be variable, and selectable under the control of the micro-controller. The appropriate level of attenuation typically would be determined by the amount the incident light exceeds the predetermined brightness level. In other words, the greater the amount by which the incident light exceeds the predetermined brightness level in a particular region, the greater would be the level of attenuation at which the pixels in the corresponding location would be attenuated. The relevant appropriate levels of attenuation could be computed by the micro-controller, or alternatively, could be obtained from a look-up table which would correlate appropriate levels of attenuation with amounts by which the brightness of the incident light exceeds the predetermined brightness level.

Claims

1. A device for minimising glare from a light source characterised in that the device (1 ) comprises a panel (5) defining a lens area (4) for placing in the field of view of a subject of one eye thereof, the panel (5) comprising an electro-optical medium (20) defining at least one pixel (26,27) in the lens area (4), the pixel (26,27) being selectively and alternately operable in a light transmitting mode for accommodating light substantially unimpeded therethrough, and in a light attenuating mode for attenuating light passing therethrough, a monitoring means (40) for monitoring the level of light in the field of view of the subject, and a control means (39) responsive to the monitoring means (40) for selectively operating at least one of the pixels (26,27) in a light attenuating mode at a location in the lens area (4) corresponding to a region in the field of view in which the level of incident light is determined as exceeding a predetermined light level for minimising glare from the light source.

2. A device as claimed in Claim 1 characterised in that the control means (39) comprises a computing means (42) responsive to the monitoring means (40) for computing the average level of light in the field of view, and the predetermined level of light at which the control means (39) is responsive for operating the pixels (26,27) in the light attenuating mode is a predetermined light level above the computed average level of light.

3. A device as claimed in Claim 1 or 2 characterised in that each pixel (26,27) is operable at one level of attenuation in the light attenuating mode.

4. A device as claimed in any preceding claim characterised in that each pixel (26,27) is operable at a plurality of levels of attenuation in the light attenuating mode.

5. A device as claimed in any preceding claim characterised in that the level of attenuation at which each pixel (26,27) to be operated in the light attenuating mode is a function of the amount by which the light incident in the corresponding region of the field of view exceeds the predetermined light level.

6. A device as claimed in any preceding claim characterised in that the panel (5) defines a pair of lens areas (4) for placing adjacent the respective eyes of the subject in the field of view thereof.

7. A device as claimed in any of Claims 1 to 5 characterised in that a pair of panels (5) are provided, each panel (5) defining a lens area (4) for placing adjacent the corresponding one of the eyes of the subject in the field of view thereof.

8. A device as claimed in Claims 6 or 7 characterised in that the pixels (26,27) in corresponding locations of the respective lens areas (4) are operated by the control means (39) at respective different levels of attenuation in response to the level of light in a corresponding region exceeding the predetermined light level.

9. A device as claimed in any of Claims 6 to 8 characterised in that the control means (39) operates the pixels (26,27) in locations in the respective lens areas (4) corresponding to a region in the field of view in which the incident light exceeds the predetermined light level, such that the level of attenuation at which each pixel (26,27) to be attenuated at the location in one of the lens areas (4) is greater than the level of attenuation at which each pixel (26,27) in the corresponding location of the other lens area (4) is operated.

10. A device as claimed in Claim 9 characterised in that each pixel (26,27) in the location in one of the lens areas (4) in which each pixel (26,27) is operated at the greater level of attenuation is operated at a level of attenuation in the range of 40% to 95%, and each pixel (26,27) in the corresponding location in the other one of the lens areas (4) is operated at a level of attenuation in the range of 0% to 60%.

11. A device as claimed in Claim 10 characterised in that each pixel in the location in one of the lens areas in which each pixel is operated at the greater level of attenuation is operated at a level of attenuation in the range of 50% to 95%, and each pixel in the corresponding location in the other one of the lens areas is operated at a level of attenuation in the range of 10% to 55%.

12. A device as claimed in Claim 11 characterised in that each pixel in the location in one of the lens areas in which each pixel is operated at the greater level of attenuation is operated at a level of attenuation in the range of 65% to 85%, and each pixel in the corresponding location in the other one of the lens areas is operated at a level of attenuation in the range of 40% to 55%.

13. A device as claimed in Claim 12 characterised in that each pixel in the location in one of the lens areas in which each pixel is operated at the greater level of attenuation is operated at a level of attenuation of approximately 75%, and each pixel in the corresponding location in the other one of the lens areas is operated at a level of attenuation of approximately 50%.

14. A device as claimed in any of Claims 9 to 13 characterised in that the lens area in which the pixels are operated at the greater level of attenuation corresponds to the right-hand eye of the subject.

15. A device as claimed in any of Claims 9 to 13 characterised in that the lens area in which the pixels are operated at the greater level of attenuation corresponds to the left-hand eye of the subject.

16. A device as claimed in any preceding claim characterised in that a plurality of pixels are provided in each lens area.

17. A device as claimed in Claim 16 characterised in that the pixels (26) in each lens area (4) are arranged to form a band (32) extending transversely across each lens area (4) from one of the left and right-hand sides thereof.

18. A device as claimed in Claim 17 characterised in that the band of pixels is located in each lens area to be above the normal line of sight of the subject.

19. A device as claimed in Claims 17 or 18 characterised in that the band of pixels in each lens area extends from the one of the left and right-hand sides of the lens area towards the other side thereof.

20. A device as claimed in any of Claims 17 to 19 characterised in that the band (32) of pixels (26) in each lens areas (4) terminates (35) intermediate the centre of the corresponding lens area and the side towards which the band is extending.

21. A device as claimed in any of Claims 17 to 20 characterised in that a greater number of pixels are provided in each lens area towards the one of the left and right- hand sides from which the corresponding band of pixels extends.

22. A device as claimed in Claim 21 characterised in that at least one pixel (27) is provided extending downwardly from the band (32) of pixels (26) in each lens area (4) adjacent the one of the left and right-hand sides from which the corresponding band (32) of pixels (26) extend.

23. A device as claimed in any of Claims 17 to 22 characterised in that the band of pixels in each lens area extends from the left-hand side thereof.

24. A device as claimed in any of Claims 17 to 22 characterised in that the band of pixels in each lens area extends from the right-hand side thereof.

25. A device as claimed in any of Claims 17 to 24 characterised in that each pixel in the band of pixels in each lens area extends the width of the band.

26. A device as claimed in any preceding claim characterised in that each pixel in each lens area is operable in the light attenuating mode on being powered up, and is operable in the light transmitting mode on being powered down.

27. A device as claimed in any preceding claim characterised in that the electro- optical medium (20) of each panel (5) is a cholesteric liquid crystal medium.

28. A device as claimed in any preceding claim characterised in that each panel (5) comprises a first substrate (11) and a second substrate (12), and the electro- optical medium (20) is sandwiched between the respective substrates (11 ,12).

29. A device as claimed in Claim 28 characterised in that a single electrode (25) is provided on one (12) of the first and second substrates (11 ,12) adjacent the electro-optical medium (20), and a plurality of pixel defining electrodes (24) are provided on the other (11) of the first and second substrates (11 ,12) for co-operating with the single electrode (25) for defining the respective pixels (26,27) in the corresponding lens area (4).

30. A device in claimed in Claim 29 characterised in that a plurality of electrically conductive tracks (30) are provided on the substrate (11) carrying the plurality of electrodes (24) for addressing the respective electrodes (24), and an area (31 ) of the other (12) of the first and second substrate (11 ,12) on which the single electrode (25) is formed is provided free of electrode , the area (31 ) free of electrode corresponding to the addressing tracks (30) for preventing the addressing tracks (30) co-operating with the single electrode (25) for defining unwanted pixels.

31. A device as claimed in any preceding claim characterised in that the control means is responsive to the level of brightness of the light incident in a region of the field of view exceeding a predetermined light brightness level for operating the at least one of the pixels in the light attenuating mode.

32. A device as claimed in any of preceding claim characterised in that the monitoring means (40) is located intermediate the lens areas.

33. A device as claimed in any preceding claim characterised in that the device comprises spectacles (1) having a pair of lens receiving portions (3), and one of the panels (5) defining the lens area (4) being located in each lens receiving portion (3).

34. A device as claimed in Claim 33 characterised in that the monitoring means (40) is provided on a bridge piece (6) of the spectacles (1) extending between the respective lens receiving portions(3).

35. A device as claimed in any of Claims 1 to 32 characterised in that the device comprises a visor.

36. A device as claimed in Claim 35 characterised in that the visor comprises a pair of lens receiving portions, and one of the panels defining the lens area being located in each lens receiving portion.

37. A device as claimed in Claim 35 characterised in that the visor comprises a panel receiving portion, and the panel which defines respective lens areas being located in the panel receiving portion.

38. A device as claimed in any of Claims 35 to 37 characterised in that the monitoring means is provided intermediate the respective lens areas.

39. A device as claimed in any preceding claim characterised in that the device is suitable for wearing by a driver driving on the right hand side of the road, and the band of pixels in each lens area extends from the left hand side of each lens area.

40. A device as claimed in any preceding claim characterised in that the device is suitable for wearing by a driver driving on the left hand side of the road, and the band of pixels in each lens area extends from the right hand side of the lens area.

41. A device as claimed in Claim 40 characterised in that the pixels in the lens area corresponding to the right hand eye of the subject to be operated in the attenuating mode are operated at the greater level of attenuation.

42. A device as claimed in any preceding claim characterised in that the control means (39) comprises drivers (43,44) for driving the respective pixels in each lens area.

43. A device as claimed in any preceding claim characterised in that the monitoring means (40) comprises a camera.

44. A device as claimed in Claim 43 characterised in that the camera is a CMOS camera.

45. A method for minimising glare from a light source, characterised in that the method comprises the steps of placing a panel defining a lens area in the field of view of a subject with the lens area in the field of view of one eye thereof, the panel comprising an electro-optical medium defining at least one pixel in the lens area, the pixel being selectively and alternately operable in a light transmitting mode for accommodating light substantially unimpeded therethrough, and in a light attenuating mode for attenuating light passing therethrough, monitoring the level of light in the field of view of the subject, determining if the level of light exceeds a predetermined light level, and in response to the level of light incident in a region in the field of view of the subject exceeding the predetermined light level operating at least one of the pixels in a location of the lens area corresponding to the region in the field of view in which the level of light exceeds the predetermined light level in the light attenuating mode for attenuating the light at the location for minimising glare from the light source.

46. A method as claimed in Claim 45 characterised in that the average level of light in the field of view of the subject is computed, and on the level of light incident in a region of the field of view being above the computed average light level by a predetermined light level, one pixel in a location of the lens area which corresponds to the region in which the level of light exceeds the predetermined light level is operated in the light attenuating mode.

47. A method as claimed in Claims 45 or 46 characterised in that each pixel in the location corresponding to the region of the field of view in which the level of light exceeds the predetermined light level is operated in the light attenuating mode.

48. A method as claimed in any of Claims 45 to 47 characterised in that each pixel is operated in the light attenuating mode at a level of attenuation which is a function of the amount by which the light level in the corresponding region of the field of view exceeds the predetermined light level.

49. A method as claimed in any of Claims 45 to 48 characterised in that the panel defines two lens areas, and the panel is placed in the field of view with the respective lens areas adjacent the corresponding eyes of the subject.

50. A method as claimed in any of Claims 45 to 48 characterised in that a pair of panels each defining one lens area are placed in the field of view of the subject adjacent the corresponding eyes of the subject.

51. A method as claimed in Claim 49 or 50 characterised in that each pixel in the location of one of the lens areas corresponding to the region in the field of view in which the light level exceeds the predetermined light level is operated at a greater level of attenuation than each pixel in the corresponding location of the other lens area.

52. A method as claimed in Claim 51 characterised in that each pixel in the location in one of the lens areas in which each pixel is operated at the greater level of attenuation is operated at a level of attenuation in the range of 40% to 95%, and each pixel in the corresponding location in the other one of the lens areas is operated at a level of attenuation in the range of 0% to 60%.

53. A method as claimed in Claim 52 characterised in that each pixel in the location in one of the lens areas in which each pixel is to be operated at the greater level of attenuation is operated at a level of attenuation in the range of 50% to 95%, and each pixel in the corresponding location in the other one of the lens areas is operated at a level of attenuation in the range of 10% to 55%.

54. A method as claimed in Claim 53 characterised in that each pixel in the location in one of the lens areas in which each pixel is to be operated at the greater level of attenuation is operated at a level of attenuation in the range of 65% to 85%, and each pixel in the corresponding location in the other one of the lens areas is operated at a level of attenuation in the range of 40% to 55%.

55. A method as claimed in Claim 54 characterised in that each pixel in the location in one of the lens areas in which each pixel is to be operated at the greater level of attenuation is operated at a level of attenuation of approximately 75%, and each pixel in the corresponding location in the other one of the lens areas is operated at a level of attenuation of approximately 50%.