PROPERTY ORGANIZATION
`PCT WORLD INTELLECTUAL
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`International Bureau
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`INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
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`6 :
`(51)International Patent Classification
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`(11)International Publication Number: WO 98/54030
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`B60Q 1/14
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`1998 (03.12.98) (43)International Publication Date:3 December
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`AL, AM, AT, AU, AZ, BA, BB, BG, BR,
`(21)International Application Number: PCT/NL98/00310
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`(81)Designated States:
`BY, CA, CH, CN, CU, CZ, DE, DK, EE, ES, FI, GB, GE,
`GH, GM, GW, HU, ID, IL, IS, JP, KE, KG, KP, KR, KZ,
`(22)International Filing Date: 28 May 1998 (28.05.98)
`LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, MW,
`MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL,
`TJ, TM, TR, TT, UA, UG, US, UZ, VN, YU, ZW, ARIPO
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`patent (GH, GM, KE, LS, MW, SD, SZ, UG, ZW), Eurasian
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`patent (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), European
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`patent (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR,
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`IE, IT, LU, MC, NL, PT, SE), OAP! patent (BF, BJ, CF,
`RAFSHULT
`(for all designated States except US):
`
`(71) Applicant
`CG, Cl, CM, GA, GN, ML, MR, NE, SN, TD, TG).
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`[NL/NL]; Ravelstraat 3, NL-2162 AP Lisse (NL).
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`(30)Priority Data:
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`1006156 29 May 1997 (29.05.97) NL
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`(72)Inventor; and
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`(for US only): KARLSSON, Lars, Erik, Published
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`(75)Inventor/Applicant
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`Anders [NL/NL]; Ravelstraat 3, NL-2162 AP Lisse (NL). With international
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`search report.
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`(74)Agent: VAN KAN, J., J., H.; Algemeen Octrooibureau,
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`World Trade Center, Past. Petersstraat 160, NL-5612 LV
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`Eindhoven (NL).
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`PATTERNLIGHTING (54)Title: A LIGHTING DEVICE HAVING A CONTROLLABLE
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`(57)Abstract
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`a light beamfor producing means (27) arranged comprising lighting a headlight of a motor vehicle, A lighting device, in particular
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`(7)to be emitted by the lighting device in response to a control signal delivered by light-sensitive sensor means (23) during operation. The
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`meansby the lighting lighting device comprises means (28) for intermittently, repeatedly controlling the intensity of the light (4) emitted
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`(27)in a manner which is not visible to the human eye. Control means connect to the sensor means (23) in such a manner that the control
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`delivered by the sensor means (23) during a period of low intensity of the lighting means (27) is processed so as to vary the pattern
`signal
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`of the light beam (7). In this manner an accurate measurement of ambient light (11), which is not disturbed by the lighting device's own
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`for detecting light from oncoming traffic. As a result, the lighting pattern and the lighting
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`lighting means (27), is provided, for example
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`a light intensity which istraffic will not be blinded, thus permitting
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`intensity are automatically adjusted, in such a manner that oncoming
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`a lighting device
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`which is built up of spotlight
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`generally higher than that of conventional dipped headlights, for example. More in particular,
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`beams and spotlight sensors is provided.
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`Mercedes EX1010
`U.S. Patent No. 11,208,029
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`

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`FOR THE PURPOSES OF INFORMATION ONLY
`
`Codes used to identify States party to the PCT on the front pages of pamphlets publishing international applications under the PCT.
`
`AL
`AM
`AT
`AU
`AZ
`BA
`BB
`BE
`BF
`BG
`BJ
`BR
`BY
`CA
`CF
`CG
`CH
`CI
`CM
`CN
`cu
`CZ
`DE
`DK
`EE
`
`Albania
`Annenia
`Austria
`Australia
`Azerbaijan
`Bosnia and Herzegovina
`Barbados
`Belgium
`Burkina Faso
`Bulgaria
`Benin
`Brazil
`Belarus
`Canada
`Central African Republic
`Congo
`Switzerland
`CIJte d'Ivoire
`Cameroon
`China
`Cuba
`Czech Republic
`Gennany
`Denmark
`Estonia
`
`ES
`FI
`FR
`GA
`GB
`GE
`GH
`GN
`GR
`HU
`IE
`IL
`IS
`IT
`JP
`KE
`KG
`KP
`
`KR
`KZ
`LC
`LI
`LK
`LR
`
`Spain
`Finland
`France
`Gabon
`United Kingdom
`Georgia
`Ghana
`Guinea
`Greece
`Hungary
`Ireland
`Israel
`Iceland
`Italy
`Japan
`Kenya
`Kyrgyzstan
`Democratic People's
`Republic of Korea
`Republic of Korea
`Kazakstan
`Saint Lucia
`Liechtenstein
`Sri Lanka
`Liberia
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`LS
`LT
`LU
`LV
`MC
`MD
`MG
`MK
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`ML
`MN
`MR
`MW
`MX
`NE
`NL
`NO
`NZ
`PL
`PT
`RO
`RU
`SD
`SE
`SG
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`Lesotho
`Lithuania
`Luxembourg
`Latvia
`Monaco
`Republic of Moldova
`Madagascar
`The fonner Yugoslav
`Republic of Macedonia
`Mali
`Mongolia
`Mauritania
`Malawi
`Mexico
`Niger
`Netherlands
`Norway
`New Zealand
`Poland
`Portugal
`Romania
`Russian Federation
`Sudan
`Sweden
`Singapore
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`SI
`SK
`SN
`sz
`TD
`TG
`TJ
`TM
`TR
`TT
`UA
`UG
`us
`uz
`VN
`YU
`zw
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`Slovenia
`Slovakia
`Senegal
`Swaziland
`Chad
`Togo
`Tajikistan
`Turkmenistan
`Turkey
`Trinidad and Tobago
`Ukraine
`Uganda
`United States of America
`Uzbekistan
`Viet Nam
`Yugoslavia
`Zimbabwe
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`

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`WO 98/54030
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`PCT/NL98/00310
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`1
`A lighting device having a controllable lighting pattern.
`
`The
`invention relates
`to a
`lighting device,
`in
`particular a headlight of a motor vehicle, comprising lighting means
`arranged for generating and varying the pattern of a light beam to be
`emitted by the lighting device in response to at least one control signal
`delivered by light-sensitive sensor means during operation.
`A lighting device of
`this
`type
`is known
`international patent application WO 86/05147.
`Lighting devices, such as headlights of motor vehicles,
`have to comply with specified national and/or international regulations,
`in particular with regard to preventing the blinding or glare of oncoming
`traffic.
`
`from
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`In accordance with said regulations, a headlight of
`a motor vehicle, such as a car, is not allowed to emit light exceeding
`a specified intensity in specified directions. During normal use of the
`car, when driving with dipped headlights, the risk of blinding oncoming
`traffic as defined in the respective regulations is practically zero. When
`driving with main-beams, however, oncoming traffic is easily blinded, since
`the main-beams are designed and optimized for long-range illumination.
`In many cases, in particular when driving on dark, unilluminated roads,
`it is highly desirable to be able to utilize the higher light intensity
`and the l anger-range main-beam constantly, which contributes towards
`increased road safety and driving comfort. This raises the problem of
`blinding oncoming traffic which,
`in
`turn, may
`lead
`to a hazardous
`situation.
`
`Blinding of traffic on the other side of the road may
`occur not only when driving with high beams or main-beams, but also when
`driving with low beams or dipped headlights, for example in the case of
`quick acceleration of the vehicle. In the latter case, the position of
`the vehicle, as well as that of the headlights, with respect to the road
`surface, will deviate
`from
`the normal horizontal position and,
`consequently, also the inclination of the light beam being emitted with
`respect to the road surfac2 will be different. This phenomenon al so occurs
`when vehicles are overloaded or when headlights are badly adjusted. When
`taking a bend there is also the problem that the road ahead of the vehicle
`is insufficiently lit, because the light beam is generally optimized for
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`2
`straight movement (rather than turning movement) of the vehicle.
`The prior art lighting device comprises a light(cid:173)
`sensitive sensor, which detects the distribution and the intensity of light
`in the area ahead of a vehicle. The pattern of the light beam being emitted
`by
`the lighting device is automatically and dynamically adapted
`in
`dependence on the intensity and the direction of the light being detected.
`That is, that part of the light beam which might cause inconvenience to
`oncoming traffic is automatically suppressed, whilst retaining an optimum
`lighting effect for the driver of the vehicle himself.
`It has been proposed to dispose the light sensor near
`the windscreen of the vehicle, for example, such that each headlight is
`controlled by its own sensor.
`From an assembly point of view, the separate mounting
`of the headlights and the sensors is not to be preferred, because this
`requires additional assembly time, additional wiring, additional alignment
`operations and
`the like, which significantly adds
`to
`the cost of
`production, in particular in the case of mass production, for example in
`the automotive industry.
`From European patent application No. 0 541 491 a
`lighting device is known, wherein the lighting means and a light-sensitive
`sensor are disposed in one housing, which facilitates assembly. In this
`arrangement, however,
`the sensor is exposed to diffuse light and to
`undesirable reflected light, inter alia from the lighting device's own
`lighting means.
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`In particular when the lighting device is used in a
`headlight of a vehicle, the presence of dirt on the headlight causes a
`substantial degree of reflection of light from the device's own lighting
`means and attenuation of the external light detected by the sensor, which
`has an adverse effect on the sensitivity of the device.
`Consequently, the objective of the invention is to
`provide a lighting device, in particular a headlight of a motor vehicle,
`wherein the pattern of the emitted light beam is varied automatically in
`an efficient manner and with maximum sensitivity in response to at least
`one control signal delivered by light-sensitive sensor means during
`operation.
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`device according
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`In order to accomplish that objective the lighting
`to
`the
`invention comprises control means
`for
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`PCT/NL98/003 l 0
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`3
`intermittently, repeatedly controlling the intensity of the light emitted
`by the lighting means in a manner which is not visible to the human eye,
`wherein the control means connect to the sensor means in such a manner
`that the control signal delivered by the sensor means during a period of
`low intensity of the lighting means is processed for the purpose of varying
`the pattern of the light beam.
`In accordance with the invention a partial dimming
`system is provided, wherein the possibly disturbing influence of the
`lighting device's own lighting means on the sensor means is effectively
`reduced by decreasing the light intensity of the lighting means during
`the detection by the light sensor means, or, as in another embodiment of
`the invention, by even switching off the light altogether. By varying the
`light intensity in such a rhythm or for such a short time period that the
`variations in the light intensity are not visible to the human eye, a
`quasi-continuous light beam can be provided, whereby only ambient light
`and/or light from oncoming traffic is reliably detected.
`International patent application W095/12502 discloses
`switching on and off of a headlight of a motor vehicle, however not for
`the purpose of accurately measuring ambient light and light of oncoming
`traffic preventing glare caused by the light source of the headlight
`itself, according to the present invention.
`In conjunction with the switched headlight, WO 95/12502
`discloses switching on and off an anti-dazzle mirror to allow the driver
`of the vehicle to see its own light pulse and not the light of other
`vehicles equipped with conventional headlights or with pulsed or flashing
`headlights.
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`The sensor means and the lighting means according to
`the present invention can be advantageously combined
`into a single
`integrated lighting device, whereby the field of view of the light-
`sensitive sensors and the illumination field of the light beam to be
`emitted, will coincide. It will be appreciated that this gives designers
`a high degree of freedom, which is in particular desirable when the
`lighting device is used as a headlight in motor vehicles of different types
`and dimensions, whereby it is furthermore possible to comply with relevant
`national and international regulations.
`In case there if no other lighting system present or
`the vehicle the control means for controlling the lighting means are
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`PCT /NL98/00310
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`4
`preferably arranged in such a manner that the lighting means of the various
`vehicles are mutually controlled differently. This, in order to prevent
`situations wherein light from vehicles which are controlled precisely
`synchronously is not detected. To this end, the control may be selected
`at random or as unique or pseudo-unique pulse sequences per individual
`vehicle.
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`In particular in those cases where the headlight is
`dirty, it will be advantageous to vary the average light intensity of the
`lighting means as well. In the case of an integrated lighting device,
`wherein the sensor means and the lighting means are combined in the
`headlight, the degree of fouling of the headlight can be determined by
`measuring the amount of reflected light. The signal delivered by the light(cid:173)
`sensitive sensor means when the lighting means are on, is thereby a measure
`for the amount of reflected light. Assuming, of course, that the sensor
`means are not exposed to any light or a similar amount of light from other
`sources.
`
`In a preferred embodiment of the invention, the average
`intensity of the light emitted by the lighting means is controlled such
`to provide a light beam, the intensity of which is optimally adapted to
`the road and to the ambient light, thereby increasing the driving comfort
`and road safety. An advantage, in the long run, of motor vehicles equipped
`with lighting devices according to the invention is that the illumination
`by
`lamp posts on roads outside urban areas could be reduced,
`thus
`contributing to the conservation of energy.
`In a further preferred embodiment of the lighting device
`according to the invention, the lighting means comprise a plurality of
`controllable spotlight beams as well as means for adjusting the light
`intensity of the spotlight beams in response to the sensor means, so as
`to provide a compound light beam having a desired pattern. In accordance
`with the invention, the light beam may be composed of a large number of
`spotlight beams.
`
`The term spotlight beam used within the framework of
`the invention and of the present description is understood to mean a light
`beam comparable to the light beam emitted by a light source of limited
`physical dimensions, such as a light-emitting diode.
`The spotlight beams can be made up of separate,
`spatially distributed, pixel type light sources, for example a plurality
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`PCT /NL98/003 l 0
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`5
`of light-emitting diodes, or, as in another embodiment of the invention,
`by the spatially distributed ends of optical fibres, at the other end of
`which a single light source or a plurality of light sources is disposed.
`According to the invention, the spotlight beams may
`a 1 so be advantageous 1 y made up of 1 i ght modulator means, which are
`spatially distributed in such a manner that spotlight beams are formed
`from the light received by the light modulator means. The light modulator
`means, which may be of a type which transmits light or of a type which
`reflects light, are switched in such a manner during operation that the
`desired beam pattern is obtained.
`Light modulator means which are suitable for the purpose
`of the invention are, for example, the so-called 11 Suspended Particle
`Devices (SPDs) 11
`• Other suitable spatial light modulators are inter alia
`11 Liquid Crystal Devices (LCDs) 11
`, "Micro Mirrors", "Quantum Wells 11 and the
`1 i ke.
`
`In the case of sensor means used for detecting ambient
`1 ight and light from oncoming traffic as a parameter to which
`the
`pattern of the emitted 1 ight beam
`is to be adjusted, a preferred
`embodiment of the invention comprises spotlight sensors in the form of,
`for example, photosensitive diodes, photo transistors or other light(cid:173)
`sensitive semiconductor components, which are spatially distributed in
`a predetermined manner or at random so as to be capable of detecting light
`from desired directions or from all directions.
`Within the framework of the invention and the present
`description, the term spotlight sensor used herein is understood to
`indicate a light-sensitive sensor of limited, physically light-sensitive
`dimensions, which generally detects light from a specific direction.
`The use of spotlight sensors makes it possible to
`determine precisely the direction from which light is being detected, so
`that subsequently a precise adjustment of the pattern of the light beam
`can be carried out, for example so as not to emit light in the direction
`of the detected light.
`In another embodiment of the device according to the
`invention the spotlight sensors are made up of spatially distributed ends
`of optical fibres, at the other end of which light-sensitive sensors are
`disposed.
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`6
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`For intermittently control of the light emitted by the
`lighting device according to the invention, both the spotlight beams
`as well as the spotlight sensors can be switched. It will be understood,
`that this makes it possible to construct a very compact and efficient
`lighting device.
`
`In a compact, robust embodiment of a lighting device
`according to the invention, light source means, shutter means, light
`modulator means, light sensor means and lens means are provided, wherein
`the shutter means, the light modulator means and the light sensor means
`are arranged on a rotatable disc, wherein a section of the disc is non(cid:173)
`transmissive providing the shutter means and wherein the modulator means
`are comprised of a plurality of concentric arc shaped track-1 i ke segments,
`such as LCD segments, and wherein on each of the tracks at the non(cid:173)
`transmissive section of the disc light sensor means are arranged, the
`rotatable disc being arranged between the light source means and the lens
`means, such that part of the disc is illuminated by the light source
`means and the light sensor means face the lens means for receiving light
`therefrom, and wherein the light modulator means and the light sensor means
`connect to control means.
`For powering purposes, in a yet further embodiment of
`the invention, the control means are arranged at the disc and the disc
`comprises photo-voltaic ce 11 means arranged at the non-transmissive section
`of the disc facing the light source means for generation of electrical
`power for the control means, modulator means and light sensor means as
`well as power control means arranged at the disc.
`In addition to comprising light-sensitive sensors,
`the sensor means may also comprise one or more inclination sensors for
`detecting any deviation from the horizontal position upon acceleration
`or deceleration of the vehicle, or in those cases where the vehicle is
`overloaded or where the headlights are incorrectly adjusted, and/or
`direction sensors, for detecting whether a vehicle is taking a bend, for
`example a direction sensor which is responsive to the steering wheel of
`a vehicle.
`
`In addition to means for automatically adjusting the
`pattern of the light beam being emitted, also means for manually adjusting
`said pattern may be provided, which means may, for example, be switched
`in such a manner that manual adjustment takes precedence over automatic
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`PCT/NL98/00310
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`7
`adjustment of the beam pattern. In this connection the usual light switches
`which are, for example, present
`in a car for switching to dipped
`headlights, to parking lights or to main-beam headlights may be considered.
`The invention will be discussed in more detail hereafter
`with reference to the accompanying drawings, in which:
`Figure 1 schematically shows a first embodiment of the
`invention, which comprises a light-sensitive sensor.
`Figure 2 schematically shows a second embodiment of
`the invention, which comprises a light-sensitive sensor.
`Figure 3 schematically shows a third embodiment of the
`invention, which comprises a light-sensitive sensor.
`Figure 4 schematically shows a fourth embodiment of
`the invention, which comprises a light-sensitive sensor.
`Figure 5a, b schematically show an embodiment of the
`invention having switching means for switching the light.
`Figure 6 schematically shows part of a front view of
`a lighting device according to one embodiment of the invention, which
`comprises spotlight beams.
`Figure 7 schematically shows an embodiment of the
`invention according to Figure 6, wherein optical fibres are used.
`Figure 8 schematically shows a sixth embodiment of the
`invention, which comprises a light sensor which is built up of optical
`fibres.
`
`Figure 9 schematically shows the arrangement of optical
`fibres switched as spotlight beams and as spotlight sensors.
`Figure 10 schematically shows a yet further embodiment
`of the invention, essentially combining the embodiments of Figures 5a and
`8.
`
`Figure 11 shows a very compact, robust embodiment of
`the invention, wherein light switching means, light modulator means and
`light-sensitive sensor means as well as control and powering means are
`arranged on a single rotatable disc.
`Figure 12 schematically shows an enlarged plan view
`of the disc shown in Figure 11 viewed from the lens means.
`Figure 13 schematically shows a possible spatial
`distribution of spotlight beams and spotlight sensors in an embodiment
`according to the invention.
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`Figure 14 shows another possible spatial distribution
`of spotlight beams and spotlight sensors according to the invention.
`Figure 15 is an electric block diagram of a lighting
`device according to the invention.
`Figure 16 shows the use of the 1 i ght i ng device according
`to the invention in a motor vehicle, such as a car which is equipped with
`direction sensors and with inclination sensors.
`In the description below, like parts or parts having
`like functions bear the same reference numerals.
`Figure 1 schematically shows a first embodiment of a
`lighting device 1 according to the invention, which comprises lighting
`means in the form of a light source 2 and light modulator means 3. The
`light modulator means 3 are disposed opposite the 1 i ght source 2,
`in
`such a manner that light 4 from the light source 2 incidences the light
`modulator means 3. Light 5 which is transmitted by the light modulator
`means 3 incidences a lens 6, which forms light 5 into a desired emitted
`light beam 7. The light source 2, the light modulator means 3 and the
`lens 6 are arranged on an optical axis 8.
`The embodiment of Figure 1 comprises sensor means
`consisting of a light-sensitive sensor 9 and a further lens 10 disposed
`on the side of sensor 9 that is exposed to the incident light, such that
`incident light 11 on the lens 10 is formed into an incident light beam 12
`on light-sensitive sensor 9. The light-sensitive sensor 9 and the further
`lens 10 are arranged on a common optical axis 13.
`The light source 2 and the light modulator means 3 are
`each connected to outputs 16, 17 of control means 14, to an input 15 of
`which the light-sensitive sensor 9 is connected. In accordance with the
`invention, the control means 14 are arranged for intermittently repeatedly
`control of the intensity of the light emitted by the lighting means, by
`either controlling the light source 2 or the light modulator 3, in a manner
`which is not visible to the human eye. The light source 2, the light
`modulator means 3, the lenses 6 and 10, and the light-sensitive sensor
`9 can be arranged as a single unit in a housing 18 which is, for example
`provided with a cover glass or glass envelope 19, as is indicated in broken
`lines. Also the control means 14 can be arranged therein, if desired. For
`the sake of clarity, the electric energy source or the power supply source
`for the light source 2, the light modulator means 3 and, if necessary,
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`PCT/NL98/00310
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`9
`the light-sensitive sensor 9 are not shown in the figure. The operation
`of the device is as follows.
`The light modulator means 3 are controlled by the
`control means 14 in such a manner that the light 4 emitted by the light
`source 2 is processed into a light beam 7 having a desired pattern and
`intensity. The desired pattern and intensity of the light beam 7 are
`determined on the basis of the light 11 that is detected by the light(cid:173)
`sensitive sensor 9 via the further lens 10.
`According to the invention, the lighting means 2, 3
`are intermittently controlled by control means 14, such that the incident
`light 11 on the light-sensitive sensor 9 during a period of low intensity
`of the lighting means is processed into an electric control signal on
`input 15 of the control means 14. That is, the electric signal fed to
`the input 15 of the control means 14 by the light-sensitive sensor 9 is
`processed by the control means 14 into output signals at outputs 16, 17
`thereof, so as to control the lighting means 2, 3 in such a manner that
`a light beam 7 having a desired pattern and a desired intensity is emitted.
`When the lighting device 1 is used as a headlight in
`a car, the pattern and the intensity of the light beam 7 are, for example,
`controlled in such a manner that no light at all or light having a low
`intensity is emitted in those directions from which light is detected
`by the light-sensitive sensor 9. In this manner glaring or blinding of
`oncoming t ra f fi c is ef feet i ve l y prevented, for example, whereby the
`lighting means 2, 3 can operate with a light intensity and with a light
`beam which are optimally adapted to the road and to the ambient light,
`which will significantly increase the driving comfort and the road safety.
`The control means 14 are preferably arranged to switch
`the incident light 5 on the lens 6 periodically on and off or repeatedly
`interrupt same for a short period of time, respectively. During the dark
`period, that is, during the time that the light 5 is off, the light
`detected by the sensor 9 is measured and processed without the measurement
`by the sensor 9 being affected, for example, by reflected light being
`scattered by the cover glass 19 as indicated by dashed arrows.
`This is advantageous in particular with dirty cover
`glasses 19, which are capable of producing a large amount of scattered
`reflected light, in the order of 20% of the light 5 emitted by the light
`source 2. In view of the short distance between the cover glass 19 and
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`the sensor 9 (approx. 10 cm in the case of a headlight) and the light which
`can be detected at distances of approx. 2 km, it applies that in fact an
`amount of scattered light of 0,1% is already too much to enable a reliable
`measurement for preventing blinding.
`In order to compensate for loss of light caused by the
`presence of dirt on the cover glass 19, the control means 14 are preferably
`arranged for controlling the average light intensity of the light beam 7
`as well. The degree of fouling can be determined by measuring the signal
`from the sensor 9 while the light source 2 is on. When the cover glass
`is very dirty, incident ambient light will hardly play a role, so that
`the measured signal will provide a reliable indication of the degree of
`fouling.
`
`Those skilled in the art will appreciate that a desired
`reduction of the disturbing influence of the light source's 2 own light
`can also be achieved by switching the light 5 to a reduced intensity. The
`latter may, for example, be the case when the light source 2 may not be
`switched off completely, and/or when the light modulator means 3 cannot
`block the light 4 emitted by the light source 2 completely. That is, in
`the embodiment shown in Figure 1, the reduction according to the invention
`of the intensity of the light beam 7 being emitted can be achieved by
`controlling the intensity of the light source 2 and/or by controlling the
`light modulator means 3. Consequently, in addition to being controlled
`to form a specified pattern of the incident light 5 on the lens 6, the
`light modulator means 3 can also be controlled to temporarily block the
`light 5 either completely or to reduce its intensity.
`The embodiment of the lighting device according to
`Figure 1 utilizes light modulator means 3 which can be controlled to block
`light or to transmit light. In practice, however, light modulator means
`exist which can be controlled to reflect light or not to reflect light,
`as for example the light modulator means 21 of a lighting device 20
`according to a second embodiment of the invention as shown in Figure 2.
`Light 4 which is emitted by the light source 2 is formed
`into incident light 5 on a lens 22 via the light modulator means 21 in
`their reflective condition, for the purpose of producing a light beam 7
`to be emitted. Depending on the light detected by the light-sensitive
`sensor 9, a light beam 7 having a desired pattern and a desired light
`intensity can be formed vi a the control means 14, the light source 2 and/or
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`the light modulator means 21.
`The two embodiments described in the foregoing utilize
`two separated optical systems, one for producing the light beam 7 and the
`other for detecting ambient light for controlling the pattern and the
`intensity of the light beam 7. Note, lenses 6 and 10 may be combined into
`one integrated lens thereby.
`In a preferred embodiment of the invention, as shown
`in Figure 3, a lighting device 24 is advantageously provided with a single
`opt i ca 1 system, both for producing the desired 1 i ght beam 7 and for
`detecting ambient light 11. As shown, a light-sensitive sensor 23 and light
`modulator means 3 are arranged between the light source 2 and the lens 6.
`In the arrangement shown, the light-sensitive sensor 23 is constructed
`in such a manner that it has a negligible influence, or no influence at
`all, on the light 5 that incidences lens 6 from the light source 2 via
`the light modulator means 3. Different form what is shown, the light
`modulator means 3 and the sensor 23 may be interchanged or advantageously
`combined into a single unit.
`The
`lighting device according
`to
`the
`invention
`advantageously enables the combined use of a single optical system both
`for forming the 1 i ght beam 7 to be emitted and for detecting ambient 1 i ght,
`due to the intermittently control of the lighting means 2, 3, and of the
`light-sensitive sensor 23, if desired, such that one or the other can be
`controlled to be light transmittive or light blocking, dependent on the
`relative position of the light modulator means 3 and the sensor 23 as well
`as their typical characteristics. If the light modulator means 3 are
`arranged to receive incident light in front of the sensor 23, the light
`modulator means 3 advantageously can be switched to detect light by the
`sensor 23 from a given direction or given directions.
`In particular
`for
`lighting devices of smaller
`dimensions, such as the headlights of a car, the integrated embodiment
`according to Figure 3 has significant advantages, both from an assembly
`point of view and from a maintenance point of view.
`Those skilled in the art will appreciate that when a
`light-sensitive sensor 23 is arranged between the lens 22 and the light
`modulator means 21 in the lighting device 20, in a similar manner as shown
`in Figure 3, it will also suffice to provide a single optical system.
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`Figure 4 schematically shows a fourth embodiment of
`a lighting device 25 according to the invention, which comprises a di chroi c
`mirror 26. The operation of the dichroic mirror 26 is such that light 5
`from the light modulator means 3 is transmitted, and that light 12 that
`incidences the dichroic mirror 26 from the lens 6 is reflected to the
`light-sensitive sensor 9, which
`is disposed opposite
`the dichroic
`mirror 26, as is shown in the figure. Also in this case the advantage of
`using a single optical system applies, wherein it will be apparent that
`in this embodiment no requirements need to be made of the light-sensitive
`sensor 9 as regards its influence on the light emitted by the light
`source 2. The light reflection and light transmission coefficients of the
`mirror 26 are selected such that the loss as regards light 5 is minimal
`and a sufficient amount of light is reflected towards the sensor 9.
`In the embodiments which are shown and discussed herein,
`the desired pattern and the light intensity of the light beam 7 to be
`emitted can be provided by a light source