lllllllllllllllllllllllllllljguiilsljlulgljllllllllll|||ll|l|lllllllll
`
`United States Patent [19]
`Gotou
`
`[11] Patent Number:
`[45] Date of Patent:
`
`5,562,336
`Oct. 8, 1996
`
`[54] HEAD LAMP DEVICE FOR VEHICLE
`
`[75] Inventor: Shinichirou Gotou, Saitama-ken, Japan
`
`[73] Assignee: Honda Giken Kogyo Kabushiki
`Kaisha, Tokyo, Japan
`
`[21] Appl. No.: 472,224
`[22] Filed:
`Jun. 7, 1995
`[30]
`Foreign Application Priority Data
`
`Feb. 7, 1995
`
`[JP]
`
`Japan
`
`.... .. 7-041382
`
`..................... .. B60Q 1/08
`[51] Int. Cl.6
`[52] US. Cl. ............................ .. 36%37; 362/71; 362/276;
`364/449
`[58] Field of Search ................................ .. 362/37, 61, 71,
`362/276, 802; 364/449, 424.05; 180/168
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`3/1992 Lee .......................................... .. 362/71
`5,099,400
`5,158,352 10/1992 Ikegami et a1. .
`5,193,894
`3/1993 Lietar et a1. .......................... .. 362/276
`5,247,440
`9/1993 Capurka et a1. ...................... .. 364/449
`
`9/1994 Zhang et a1. .......................... .. 180/168
`5,347,456
`FOREIGN PATENT DOCUMENTS
`
`62-77249 4/1987 Japan.
`2-296550 12/1990 Japan.
`Primary Examiner-Denise L. Gromada
`Assistant Examiner—Sara Raab
`Attorney, Agent, or Firm—-Weiner, Carrier & Burt, P.C.;
`Joseph P. Carrier; Irving M. Weiner
`[57]
`ABSTRACT
`
`A head lamp device for a vehicle in which a light distribution
`can be properly adjusted in response to a state of a road or
`a running environment and visibility can be improved is
`provided. The head lamp device for a vehicle capable of
`adjusting a lighting region in a forward direction of the
`vehicle comprises proper vehicle position sensing means for
`sensing a proper vehicle running position in a lateral direc
`tion of a road, and control means for calculating a distance
`from the proper vehicle running position to a center line on
`the road and adjusting a lighting region of the head lamp in
`such a way that the lighting region is expanded more and
`more toward the center line as the calculated distance is
`longer and longer.
`
`20 Claims, 8 Drawing Sheets
`
`Light distribution
`control routine
`
`Vehicle information inputted
`
`Road information inputted
`
`umber of lanes rangin
`from proper vehicle running
`
`lane
`
`89
`
`S11
`
`N
`
`812 Within non-sensitive range I)
`
`N
`
`514 Optical axis adjusted upward
`
`815 Light distribution controlled to
`occupy optical axis angle 6
`
`Page 1 of 16
`
`BMW 1015
`
`

`
`U.S. Patent
`US. Patent
`
`Oct. 8, 1996
`Oct. 8, 1996
`
`Sheet 1 of 8
`Sheet 1 of 8
`
`5,562,336
`5,562,336
`
`FIG]
`FIG]
`
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`
`/ «V?
`
`90
`
`Page2 of 16
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`Page 2 of 16
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`

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`US. Patent
`
`Oct. 8, 1996
`
`Sheet 2 of 8
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`5,562,336
`
`2 V
`
`K
`
`522280
`33528: SW .88:
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`Page 3 of 16
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`

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`US. Patent
`
`011. s, 1996
`
`Sheet 3 of 8
`
`5,562,336
`
`FIGA
`
`Light distribution
`control routine
`
`81
`
`S2
`
`Vehicle information inputted
`I
`Road information inputted
`
`S5
`
`Inclination K+-K1
`
`S6
`
`K<~Kz
`\I/
`
`S7
`
`K(—K3
`I
`
`S8
`
`N
`
`.
`
`S9
`
`Non-sensitive range D<—D0
`
`S10
`
`D<—D1
`I
`
`811
`
`Y
`In dwel 1%
`N
`S12 Within non-sens?itive range D
`
`‘_ 1
`
`I
`
`S13
`
`-
`
`s there centra
`eparating zone ‘I
`
`Y
`
`N
`
`S14 Optical axis adjusted upward
`I
`
`815 Light distribution control led to
`occupy optical axis angle 6
`
`Page 4 of 16
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`

`
`US. Patent
`
`0a. 8, 1996
`
`Sheet 4 of 8
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`5,562,336
`
`FIG. 5A
`
`P
`QMAX ________________________________ _-I
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`Page 5 of 16
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`

`
`US. Patent
`U.S. Patent
`
`0a. 8, 1996
`Oct. 3, 1996
`
`Sheet 5 of 8
`Sheet 5 of 8
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`5,562,336
`5,562,336
`
`5945i
`EI.f_3_._f.5_/3
`71:]
`n.—.1
`
`40
`
`
`
`
`
`Page6 of 16
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`Page 6 of 16
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`

`
`U.S. Patent
`
`Oct. 8, 1996
`
`Sheet 6 of 8
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`5,562,336
`
`F167
`
`1
`|\
`
`50-/@:! I
`
`I
`
`Page 7 of 16
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`

`
`U.S. Patent
`US. Patent
`
`Oct. 8, 1996
`0a. 8, 1996
`
`Sheet 7 of 8
`Sheet 7 of 8
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`5,562,336
`5,562,336
`
`FIG.8A
`FIG.8A
`
`FIG.8B
`FIG.8B
`
`1
`
`I‘!
`
`(
`
`:5
`
`Page 8 of 16
`
`Page 8 of 16
`
`

`
`U.S. Patent
`US. Patent
`
`Oct. 8, 1996
`0a. 8, 1996
`
`Sheet 8 of 3
`Sheet 8 of 8
`
`5,562,336
`5,562,336
`
`F 16.9
`F IG.9
`
`60
`60
`
`Page 9 of 16
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`Page 9 of 16
`
`

`
`5,562,336
`
`1
`HEAD LAMP DEVICE FOR VEHICLE
`
`FIELD OF THE INVENTION
`
`1. Background of the Invention
`This invention relates to a head lamp device for a vehicle,
`and more particularly, a device for adjusting a lighting
`region of a head lamp in response to a state in a road or a
`traveling environment.
`2. Discussion of Relevant Art
`The head lamp of a vehicle is operated such that a mnning
`beam having a lighting region capable of detecting an
`obstacle existing at a far distance at night and a passing-by
`beam having a lighting region not giving any glare on an
`opposing vehicle when a proper or subject vehicle runs aside
`of the opposing vehicle are manually changed over from
`each other.
`In addition, as a navigation system has been installed in
`a vehicle in recent years, there occurs an example in which
`a curve is estimated in advance in reference to a map
`information of a navigation system and an information of a
`position of a proper vehicle on the map, and the lighting
`region is changed in a lateral direction before entering the
`curve so as to improve visibility (Japanese Patent Laid-Open
`No. Hei 2-296550 (1990)).
`However, in the prior navigation system described above,
`a radius of curvature of the curve was estimated in advance
`in reference to vehicle information and a light distribution
`control corresponding to the radius of curvature of the curve
`was merely carried out and a ?ne light distribution control
`corresponding to the running environment such as a road
`width or a circumference around the road was not per
`formed.
`
`10
`
`25
`
`35
`
`SUMMARY OF THE INVENTION
`
`The present invention has been invented in view of the
`foregoing and it is an object of the present invention to
`provide a head lamp device for a vehicle capable of per
`forming a proper adjustment of light distribution corre
`sponding to a state of road or a running environment and
`improving visibility.
`In order to accomplish the aforesaid object, the present
`invention provides a head lamp device for a vehicle capable
`of adjusting a lighting region in a forward direction of the
`vehicle comprising proper vehicle position sensing means
`for sensing a proper vehicle running position in a lateral
`direction of a road; and control means for calculating a
`distance from said proper vehicle running position to a
`center line on the road and adjusting a lighting region of the
`head lamp such that the lighting region is more expanded
`toward the center line as said distance is longer.
`In the case that a distance from a proper vehicle to a center
`line on the road is long, the light distribution region can be
`expanded up to the center line without giving a glare to an
`opposing vehicle to improve visibility.
`The visibility can be improved in the same manner as
`above by providing running lane sensing means for sensing
`a proper vehicle running lane in a lateral direction of a road,
`and control means for calculating the number of lanes
`ranging from the running lane of said proper vehicle to a
`center line on a road and adjusting a lighting region of the
`head lamp such that the lighting region is more expanded
`toward the center line as the number of said lanes is
`increased.
`
`50
`
`55
`
`60
`
`65
`
`2
`There is provided steering angle sensing means for sens
`ing a steering angle of a steering device, and said control
`means controls an adjusting amount for a lighting region in
`response to the steering angle together with the distance
`extending up to said center line, whereby a light distribution
`at the curve is ?nely adjusted to enable a superior visibility
`to be attained.
`In a head lamp device for a vehicle capable of adjusting
`a lighting region in a forward direction of the vehicle, there
`are provided urban area sensing means for sensing if an area
`where the vehicle runs is an urban area; steering angle
`sensing means for sensing a steering angle of a steering
`device, and control means for determining an adjusting
`amount of the lighting region in response to said steering
`angle and controlling a predetermined basic n0n~sensitive
`range of the lamp to be widened when the vehicle runs in the
`urban area, wherein when the vehicle runs in the urban area,
`the light distribution is prohibited from being varied too
`sensitively in response to a steering wheel operation and a
`?ne light distribution adjustment with no inharrnonious
`feeling can be carried out.
`p
`The non-sensitive range is a range where an optical axis
`angle is not changed in respect to a variation of the steering
`angle.
`A head lamp device for a vehicle capable of adjusting a
`lighting region in a forward direction of the vehicle com
`prises dwelling area sensing means for sensing if an area
`where the vehicle runs is a dwelling area, and control means
`for controlling a lateral width of the lighting region to be
`larger than a predetermined reference value when the
`vehicle runs in the dwelling area. When the vehicle runs in
`the dwelling area, the light distribution is widened in a
`lateral direction, a road edge or a walkway can be lighted up,
`visibility of pedestrians or the like can be improved in
`particular and an adjustment of the light distribution adapted
`for environment can be carried out.
`A head lamp device for a vehicle capable of adjusting a
`lighting region in a forward direction of the vehicle com
`prises central separating area sensing means for sensing if a
`central separating zone for separating a lane where a proper
`vehicle runs from a lane for an opposing vehicle is present,
`and control means for adjusting an optical axis of said head
`lamp to an upward orientation when the vehicle runs on a
`road having the central separating zone so as to increase a
`reaching distance of the lighting region at a far side. Since
`in the case that the vehicle runs on the road having the
`central separating zone, glare on the opposing vehicle can be
`prohibited by the central separating zone, a far reaching
`distance in the lighting region can be increased and visibility
`can be improved.
`A head lamp device for a vehicle is provided with a
`receiver device for receiving information transmitted from
`an on-road transmitter, and said road width sensing means,
`said sensing means for sensing the number of lanes, said
`urban area sensing means, said dwelling area sensing means
`or said central separating zone sensing means sense a road
`width, the number of lanes, urban area, dwelling area or
`central separating zone in response to information received
`by said receiver device, thereby the state of road or the
`running environment can be easily sensed and a ?ner
`adjustment of light distribution can be performed.
`A head lamp device for a vehicle is provided with a map
`information memory device for storing map information
`including road data, and said road width sensing means, said
`sensing means for sensing the number of lanes,‘ said urban
`area sensing means, said dwelling area sensing means or
`
`Page 10 of 16
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`

`
`3
`said central separating zone sensing means sense a road
`width, the number of lanes, urban area, dwelling area or
`central separating zone in response to information stored in
`said map information memory device, thereby a state of the
`road or the running environment can be easily detected and
`a ?ner adjustment of light distribution can be performed.
`Other objects, advantages and salient features of the
`invention will be apparent from the following Description
`which, when taken in conjunction with the annexed draw
`ings, describes the preferred embodiment of the invention.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a top plan view for illustrating a light distribution
`state of a vehicle of one preferred embodiment of the present
`invention;
`FIG. 2 is a perspective view for schematically showing an
`oscillating mechanism for a head light of the present pre
`ferred embodiment;
`FIG. 3 is a schematic block diagram for showing a control
`system of the present preferred embodiment;
`FIG. 4 is a ?ow chart for showing a procedure in light
`distribution control in the present preferred embodiment;
`FIGS. 5A to 5C are views for showing relations between
`a steering angle or and an optical axis angle 6 on the
`coordinates;
`FIGS. 6A to 6C are illustrative views for showing a states
`in which light distributions are different from each other in
`view of the number of running lanes;
`FIG. 7 is an illustrative view for showing one example to
`illustrate a non-sensitive range;
`FIGS. 8A and 8B are illustrative views for showing states
`in which light distributions are diiferent from each other in
`response to whether or not a vehicle runs in a dwelling area;
`and
`FIG. 9 is an illustrative view for showing a state in which
`light distributions are diiferent from each other in response
`to presence or non-presence of the central separating region.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`
`Referring now to FIGS. 1 to 9, one preferred embodiment
`of the present invention will be described as follows.
`A vehicle 1 of the preferred embodiment is made such that
`a right head light 2R and a left head light 2L for lighting the
`front can be oscillated independently from each other in a
`lateral direction and a vertical direction. For example, in the
`FIG. 1 which is a view showing the vehicle 1 as viewed from
`above, the left head light 2L has an optical axis angle 6L on
`the left side, that is, an optical axis L of the left light head
`2L is de?ected leftward by the angle 6L in respect to a
`reference straight advance direction F of the vehicle 1. The
`optical axis of the right head light 2R is de?ected rightward
`by an optical axis angle 9R smaller than 9L. As the result,
`a lighting region 3 in front of the vehicle made by the left
`and right head lights 2L, 2R has a lateral width expanded
`while being de?ected toward the left side from the reference
`direction.
`An oscillating mechanism for the head lights 2L and 2R
`of the preferred embodiment is schematically illustrated in
`FIG. 2 in reference to one head light 2R.
`A supporting base 9 bent in an L-shape is oscillatably
`arranged at a right front end of the vehicle 1, wherein a lamp
`unit 4 of the head light 2R is ?xed to an upper end of a rotary
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`5,562,336
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`4
`shaft 5 rotatably and vertically arranged on a horizontal plate
`9a of the supporting base 9 and a worm gear 7 formed at a
`driving shaft of a motor 8 for horizontal oscillation is
`engaged with a worm wheel 6 ?tted to the rotary shaft 5.
`Accordingly, the lamp unit 4 is oscillated in a horizontal
`direction together with the rotary shaft 5 through engage
`ment between the worm gear 7 and the worm wheel 6 under
`driving of the motor 8 for horizontal oscillation.
`Within the lamp unit 4 are sprovided two kinds of
`?laments for a high beam for far distance lighting and a low
`beam for short distance lighting.
`The supporting base 9 itself is oscillatably supported,
`wherein three shafts are extended rearward from three
`corners of a vertical plate 919 so as to adjust an attitude of the
`supporting base 9, i.e. an attitude of the lamp unit 4 by the
`three shafts.
`One of the three shafts is a ?xed shaft 10 for ?xing a
`position of one comer of the vertical plate 9b. The other one
`shaft is a horizontal direction adjusting screw shaft 11. The
`shaft 11 can move a corner of the vertical plate 917 back and
`forth by being operated manually so that the supporting base
`9 can be ?nely adjusted in a horizontal direction around the
`?xed point by the ?xed shaft 10. The remaining lower
`positioned shaft is a driving screw shaft 12 of a motor 13 for
`vertical oscillation. The shaft 12 is driven by the motor 13
`to move one comer of the vertical plate 9b back and forth so
`that the supporting base 9 can be adjusted in a vertical
`direction around the ?xed point by the ?xed shaft 10.
`The motor 8 for horizontal oscillation and the motor 13
`for vertical oscillation are controlled in their driving by a
`light distribution control ECU 20.
`A schematic block diagram of a control system of the
`preferred embodiment is shown in FIG. 3 and described as
`follows.
`This vehicle 1 has a navigation system 30 mounted
`thereon, and a light distribution control ECU 20 gets map
`information, information of a proper vehicle position and
`informations relating a state of road and a running environ—
`ment from the navigation system 30. In addition, a direction
`indicating signal from a turn switch 21 which is turned on or
`off under an operation of a winker lever, a steering angle
`signal from a steering angle sensor 22 for sensing a direction
`of the steering wheel and a vehicle speed signal from a
`vehicle speed sensor 23 for sensing a vehicle speed are
`inputted to the light distribution control ECU 20. The ECU
`20 processes the inforrnations and signals so as to determine
`each of requisite optical axis angles 9L, GR, and outputs the
`indicating signal to a motor driver 24 so as to get optical axis
`angles 6L, 9R. The motor driver 24 controls the motor 8 for
`lateral horizontal oscillation and the motor 13 for vertical
`oscillation in their driving operations.
`The navigation system 30 will be described in brief. The
`navigation system ECU 31 which is a control center is
`operated such that the present position sensing part 32
`receives sensing signals from the gyro-sensor 33 and the
`vehicle speed sensor 23, calculates a moving position of the
`vehicle, performs a map matching, corrects it at a proper
`vehicle position calculated in reference to a satellite electric
`wave received by a GPS receiver 34 so as to sense an
`accurate proper vehicle position.
`The proper vehicle position calculated in this way is
`displayed at the display 36 together with the road data
`outputted by the map information outputting device 35.
`The navigation system 30 sets many predetermined points
`(nodes) which can be searched in sequence along the road.
`
`Page 11 of 16
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`5,562,336
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`5
`That is, the nodes set along the road on the map are
`arranged such that the node spacings are different from each
`other on a respective location and normally the spacings are
`wide at a straight linear road part and narrow at a curved
`road part, and the nodes are set at the crossing points without
`fail.
`Various kinds of road information on a map, for example,
`information such as road width or state of road such as a
`degree of curve at the nodes and running environment
`around the road such as in urban or dwelling areas, for
`example, are stored in compliance with each of the nodes.
`In addition, the navigation system 30 has a path guiding
`function in which the shortest path to a destination is
`calculated and then a vehicle is guided along the path.
`Referring now to the ?ow chart of FIG. 4, a procedure of
`the light distribution control in the present preferred embodi
`ment which is control led in response to the control system
`above will be described.
`As light distribution controls, there are provided an opti
`cal axis control in a horizontal direction for determining a
`relation between the steering angle or and an optical axis
`angle 9 on the basis of the road information and for actually
`controlling a driving of the motor 8 for horizontal oscilla
`tion, and an optical axis control in a vertical direction for
`controlling a driving of the motor 13 for vertical oscillation.
`At ?rst, vehicle information such as a state of the turn
`switch 21, a steering angle detected by the steering angle
`sensor 22 and a vehicle speed detected by the vehicle speed
`sensor 23 or the like are inputted (step 1) and then the map
`information i.e. the road information stored for every node
`of the navigation system 30 are inputted (step 2).
`At the next step 3, the feature of the road where the
`vehicle runs at present, in particular how many lanes are
`present in the road are judged in reference to the road
`information and then the number of lanes (11) ranging from
`the present position of the proper vehicle to the center line
`is judged.
`When the vehicle runs on the lane which is nearest to the
`center line, the operation advances to step 5 with n=1, and
`an inclination K which is a coe?icient of proportion between
`the optical axis angle 9 and the steering angle 0t is de?ned
`as K1 at step 5. If n=1 is not attained at step 3, the operation
`advances to step 4, and it is discriminated whether n22 is
`attained, i.e. whether the vehicle runs on the second lane
`from the center line. If n=2 is attained at step 4, the operation
`advances to step 6, and an inclination K=K2 is attained. If
`n=2 is not attained at step 4, the operation advances to step
`7, and an inclination K=K3 is attained. After determining the
`inclination K in such a way, the operation advances to step
`8.
`The values of the inclination K have a relation of
`K1<K2<K3.
`FIGS. 5A to 5C are views for showing relations of the
`optical axis angle 9 to be controlled of the right side head
`light 2R with respect to the steering angle or with the lateral
`axis being the steering angle or and the vertical axis being 9.
`FIG. 5A indicates a relation of both items to be determined
`at the aforesaid steps 3 to 7.
`That is, in this case, a relation of GIKOt is determined.
`Accordingly, as a value of the inclination K is higher, a
`larger variation of the optical axis angle 6 with respect to a
`steering angle or is attained.
`There is a certain limitation in the optical axis angle 6, and
`it is not controlled to be more than a maximum optical axis
`angle BMAX. Accordingly if the inclination K is determined,
`
`20
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`6
`a maximum steering angle orMAX for controlling the optical
`axis angle 6 is also determined and a control limit point
`P((XMAX, GMAX) is determined.
`FIGS. 6A to 6C illustrate states in which light distribu
`tions are different in response to the lane where the proper
`vehicle runs. It is to be noted that the vehicle 1 is running
`under a “keep to the left” type traf?c system. FIG. 6A shows
`a case in which the vehicle runs on the lane which is nearest
`to the center line 40 (n=1), FIG. 6B shows a case in which
`the vehicle runs on the lane which is the second from the
`center line 40 (n=2), and FIG. 6C shows a case in which the
`vehicle runs on the lane which is the third from the center
`line 40 (n=3). In all these cases the vehicle is approaching
`a rightward curve part.
`In the case of nzl (FIG. 6A) where the vehicle runs on the
`lane near the center line 40, the inclination K is a small value
`K11, the optical axis angle 9 is gradually changed in a
`rightward direction in response to the steering angle or, the
`light distribution region is slowly de?ected in a rightward
`direction and, therefore, it is possible to perform a suitable
`lighting of the advancing direction without applying any
`glare uselessly on an opposing vehicle by lighting toward
`the center line 40.
`As the values of n=2, 3 are being attained, the value of
`inclination K is increased up to K2, K3, a rate of variation of
`the optical axis angle 8 in a rightward direction in respect to
`the steering angle or is increased and as shown in FIGS. 6B
`and 6C, the lighting is directed rightward in a running
`direction at an early stage so as to light more a lane on the
`right side and improve a visibility of the vehicle running on
`the lane.
`Although the inclination K determined in this case is
`slightly changed at a subsequent control, the aforesaid
`control limit point P((XMAX, GMAX) is not changed.
`After the inclination K and the control limit point P((XMAX,
`BMAX) are determined as described above, the operation
`advances to step 8 and it is discriminated whether or not the
`vehicle runs on an urban area at present in reference to the
`road information of the navigation system.
`In the case that the vehicle does not run on the urban area,
`but runs on a country road for example, the operation
`advances to step 9 and sets the non-sensitive range D to DO.
`In the case that the vehicle runs on the urban area, the
`operation jumps to step 10 and sets the non~sensitive range
`D to D1.
`The non-sensitive range D de?ned heremeans a range of
`the steering angle or in which the optical axis angle is not
`changed and maintained in the state at the straight forward
`movement of the vehicle even if a steering wheel is turned.
`That is, as shown in FIG. 5B, when the steering angle 0t
`is within the non-sensitive range D, the optical axis angle is
`always ?xed to 0° or a speci?ed angle and is not changed.
`This is due to the fact that if the optical axis angle 9 is
`changed immediately in reaction to any slight steering angle
`or, it is annoying for a driver and at the same time provides
`annoyance to people around the vehicle. At urban area in
`particular, this state provides an inharmonious feeling, so
`that it is requisite that the non-sensitive region is widened,
`to prohibit the optical axis from being moved, as much as
`possible.
`In view of the above, the non-sensitive range D1 at the
`urban area is wider than the non-sensitive range D0 in the
`country road or the like.
`In the case that a steering wheel is turned in order to pass
`by a vehicle 50 parked at the road edge in a forward direction
`
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`5,562,336
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`7
`as shown in FIG. 7, for example, if the road is a country road
`a driver may not have any annoying feeling even if the
`optical axis angle is changed in compliance with the steering
`angle, and on the contrary a superior visibility can be
`attained because the surrounding area is dark. If the road is
`an urban area, changing the optical axis angle to a mere
`avoidance of the parked vehicle 50 is annoying and gives an
`inharmonious feeling. Accordingly, the optical axis angle is
`not changed and there is no problem in visibility even if the
`optical axis angle is not changed due to a bright surrounding
`in the urban area.
`In addition, upon determination of the non-sensitive range
`D, the inclination K is also slightly changed as shown in
`FIG. 5B.
`That is, a straight line QP connecting the point Q(D, 0)
`with the control limit point P(otMAX, GMAX) in the coordinates
`in FIG. 5B becomes a control line and the inclination K is
`changed into an inclination K‘ of the straight line QP.
`Since the non-sensitive range D is a quite small angle as
`compared with the maximum steering angle otMAX, a varia
`tion of the inclination is minute.
`After determining the non-sensitive range D in this way,
`it is discriminated at the step 11 whether or not the vehicle
`runs in a dwelling region at present in reference to the road
`information in the navigation system. In the case that the
`vehicle runs in a region other than the dwelling region, the
`operation advances directly to step 13 and if the vehicle runs
`in the dwelling region, the operation advances to step 12.
`In the case that the operation advances to step 12, the
`optical axis angle of each of the right and left head lights 2R
`and 2L is widened by an angle 61 in a direction opposite to
`each other within the non-sensitive range D determined at
`the aforesaid steps 9 and 10.
`That is, in the case that the vehicle runs in a region other
`than the dwelling region, the light distribution is a normal
`one directed in the straight forward direction of the vehicle
`as shown in FIG. 8A, but in the case that the vehicle runs in
`the dwelling region, the light distribution is widened later
`ally as shown in FIG. SE to light up the road edge or a
`walkway and to improve a visibility for walking persons in
`particular. Thus the light distribution adjustment adapted to
`the environments can be performed.
`Such an expansion of the light distribution as above is
`carried out within the non-sensitive range D and accordingly
`the light distribution is expanded within the non-sensitive
`region D to the speci?ed optical axis angle 61 as shown in
`FIG. 5C, resulting in that the straight line RQ' connecting the
`point R(0, 61) with the point Q'(D, 91) is a control line in the
`non-sensitive range and the straight line Q'P connecting the
`point Q'(D, 61) with the control limit point P(otMAX, GMAX)
`becomes a control line for a steering angle exceeding the
`non-sensitive range D and its inclination is changed into K".
`Though inclinations K‘ and K" are quite similar to each
`other, during running of the vehicle in the dwelling region,
`the optical axis angle 9 is determined in respect to the
`steering angle or along the bent line RQ‘P.
`The control line determining the optical axis angle 9 in
`respect to the steering angle or is de?ned through the
`foregoing steps, and at the next step 13, it is discriminated
`in reference to the road information whether or not the
`central separating zone is present in the running road. If
`there is no central separating zone, the operation advances
`directly to step 15 and if there is the central separating zone,
`the operation advances to step 14 so as to adjust the optical
`axis to an upward orientation.
`That is, the aforesaid motor 13 for vertical oscillation is
`driven to oscillate the head lights 2L, 2R upward and their
`optical axes are directed upward.
`
`15
`
`35
`
`45
`
`50
`
`55
`
`60
`
`65
`
`8
`FIG. 9 is a view for showing the state of the aforesaid light
`distribution control, and in the case that there is no central
`separating zone 60, the light distribution is a normal light
`distribution indicated by a dotted line in FIG. 9 which is a
`low beam and directed downward so as not to cause any
`glare on a vehicle running on the opposing lane. However,
`when there is the central separating zone 60, the optical axis
`is directed upward to cause a light distribution region to be
`set as indicated by a solid line in FIG. 9, for even if a far
`reaching distance is increased to improve visibility, lighting
`is interrupted by the central separating zone 60 not to cause
`any glare on a vehicle running on the opposing lane.
`As described above, adjustment of the optical axis in a
`vertical direction is carried out at step 14 and the actual light
`distribution control in a lateral horizontal direction of the
`optical axis on the basis of the control line determined at the
`aforesaid step is carried out at step 15.
`As described above, the light distribution can always be
`adjusted properly in compliance with environment, that is, in
`response to the number of lanes (n) ranging from the lane
`where the proper vehicle runs to the center line 40, whether
`the vehicle runs in the urban area or dwelling area or
`whether or not there is a central separating zone, and the
`visibility can be improved.
`Although the light distributing control in the aforesaid
`preferred embodiment is carried out by sensing the number
`of lanes (n) ranging from the proper vehicle running lane to
`the center line 40 at steps 3 to 7, it may also be possible that
`the distance ranging from the proper vehicle to the center
`line 40 is detected directly in place of the number of lanes
`and is applied to the light distribution control.
`At this time, it is necessary to detect a running position of
`the proper vehicle with high accuracy and also a high
`accuracy navigation system is required.
`In addition, in order to detect a positional relation between
`the road and the proper vehicle, it may also be applicable
`that a forward region of the proper vehicle is photographed
`with a camera and the photographic image is processed to
`detect an accurate position of the proper vehicle on the road.
`This method of utilizing a camera enables the center line
`to be detected, also enables a distance ranging from the
`accurate position of the proper vehicle on the road to the
`center line to be calculated, facilitates sensing of presence or
`non-presence of the central sepa