1:5
`United States Patent
`6,049,749
`Kobayashi
`Apr. 11, 2000
`[45] Date of Patent:
`
`[11] Patent Number:
`
`US006049749A
`
`[54] LIGHTING DEVICE FOR A VEHICLE
`
`[75]
`
`Inventor: Shoji Kobayashi, Shizuoka, Japan
`
`[73] Assignee: Koito Manufacturing Co., Ltd.,
`Tokyo, Japan
`
`[21] Appl. No.: 08/989,415
`
`[22]
`
`[30]
`
`Filed:
`
`Dec. 12, 1997
`
`Foreign Application Priority Data
`
`Dec. 13,1996
`
`[JP]
`
`Japan coccccccecscsscceeeuteesesseeee 8-353006
`
`Tmt C07ccc ccceeeeeeeneecsecseenssmaseneseees GO06F 17/00
`[ST]
`[52] U.S. Ch.eee 701/49; 701/36; 362/466;
`362/37; 362/276; 340/469
`[58] Field of Search... 701/49, 36; 362/272,
`362/276, 466, 494, 540, 541, 544, 465,
`524, 37, 40; 340/469, 471, 472
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`5/1987 Miyazaki et al. oe 362/80
`4,663,696
`
`3/1988 Shibataet al. eee 362/40
`4,733,333
`5,060,120 10/1991 Kobayashietal.
`
`5,068,768
`11/1991 Kobayashiet al.
`340/469
`5,237,306
`8/1993 Adell
`
`
`oe 362/61
`5,343,371
`8/1994 Kobayashiet al.
`5,379,196
`1/1995 Kobayashiet al... 362/61
`4/1995 Shibata etal. ....
`5,404,278
`362/83.3
`5/1995 Kobayashi et al. 362/66
`5,412,543
`
`6/1995 Kobayashi ctal.
`5,426,294
`250/226
`
`cceecee 362/41
`7/1995 Kobayashi...
`5,436,807
`5,497,306
`3/1996 Pastrick .....
`362/494
`5,562,336
`10/1996 Gotou....
`5,588,733
`12/1996 Gotou....
`5,660,454
`8/1997 Moriet al.
`... 362/466
`
`
`5,879,074
`3/1999 Pastrick .....
`w 362/494
`8/1999 Gotoh vascsssssesssesssssesssssseeieen 362/466
`5,931,572
`
`
`
`1
`
`FOREIGN PATENT DOCUMENTS
`
`43 27 780
`196 01572
`196 02 622
`
`3/1994. Germany «uu... G08G 1/0968
`.. B60Q 1/12
`8/1996 Germany ..
`
`8/1996 Germany «2... eee B600 1/06
`
`Primary Examiner—Jacques H. Louis-Jacques
`Attorney, Agent, or Firm—Sughrue, Mion, Zinn, Macpeak
`& Seas, PLLC
`
`[57]
`
`ABSTRACT
`
`A lighting device in which the vehicle advancing direction
`at which a driver aims is predicted, and the irradiating
`direction and irradiating range of a lighting device are
`controlled by comparing the result of the prediction to the
`information of the profile of a road on which the vehicle is
`running at present. The lighting device (1) includes a road
`profile calculating device (2) for finding an advancing
`direction of the vehicle in the case where the vehicle
`advances along a road on which the vehicle is running at
`present, in accordance with the map information including
`the road profile and the present position information of the
`vehicle; and a vehicle advancing direction predicting device
`(3) for predicting an advancing direction of the vehicle
`intended bya driver, by an operation signal given by the
`driver or detection information of the vehicle runningstate.
`The irradiation controller device (4) compares the direction
`data of the road profile calculating device (2) with the
`direction data of the vehicle advancing direction predicting
`device (3), the irradiation control of the lighting device (5)
`is conducted by the road profile in accordance with the
`direction data of the road profile calculating device (2) when
`a difference between them is in an allowable range, and the
`irradiation control ofthe lighting device (5) is conducted by
`the direction data of the vehicle advancing direction pre-
`dicting device (3) when the difference between them is out
`of the allowable range.
`
`10 Claims, 9 Drawing Sheets
`
`4
`
`o~
`ROAD PROFILE
`
`CALCULATING MEANS
`
`
`
`3]...
`VEHICLE ADVANCING
`TONTHOL.
`
`
`
`DIRECTION PREDICTING MEANS
`MEANS
`
`
`
`
`
`VEHICLE SPEED
`DETECTING MEANS
`
`7
`
`
`
`
`INDICATING
`MEANS
`
`
`
`VWGOA EX1008
`U.S. Patent No. 11,208,029
`
`VWGoA EX1008
`U.S. Patent No. 11,208,029
`
`

`

`U.S. Patent
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`Apr. 11, 2000
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`Sheet 1 of 9
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`6,049,749
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`U.S. Patent
`
`6,049,749
`
`Sheet 2 of 9
`
`Apr. 11, 2000
`
`FIG. 2
`
`

`

`U.S. Patent
`
`6,049,749
`
`Apr. 11, 2000
`
`Sheet 3 of 9
`
`FIG. 4
`
`
`
`

`

`U.S. Patent
`
`Apr. 11, 2000
`
`Sheet 4 of 9
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`6,049,749
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`U.S. Patent
`
`Apr. 11, 2000
`
`Sheet 5 of 9
`
`6,049,749
`
`FIG. 7
`
`18L (18R)
`
`f
`
`DRIVE SECTION
`
`t
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`

`

`U.S. Patent
`
`Apr. 11, 2000
`
`Sheet 6 of 9
`
`6,049,749
`
`FIG. 9
`
`
`
`
`INTERLOCKING MODE OF
`COMMUNICATION BETWEEN
`ROAD AND VEHICLE
`
`CALCULATION OF PRESENT
`VEHICLE POSITION
`
`
`
`
`NO
`
`MEASUREMENTOF ELAPSING TIME|_o9
`OBTAINING OF ROAD PROFILE
`
`$3
`
`IS THERE
`A ROAD BRANCH
`?
`
`
`
`PREDICTION OF VEHICLE|_sq S5 PREDICTION OF VEHICLE
`
`
`
`
`ADVANCING DIRECTION
`ADVANCING DIRECTION
`
`YES
`
`
`
`S7
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`S6
`DOESIT
`DOES IT
`
`
`COINCIDE WITH A
`COINCIDE WITH A
`
`
`DIRECTION ALONG A
`
`
`
`NO
`DIRECTION ALONG A
`NO
`ROAD?
`
`ROAD?
`
`
`
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`YES
`
`519—|
`
`
`
`IRRADIATION CONTROL
`INACCORDANCE WITH
`THE PREDICTION OF
`ADVANCING DIRECTION
`
`YES
`
`JRA$$
`
`IRRADIATION CONTROL|__ 9
`IN THE BRANCH MODE
`
`S8-
`
`IRRADIATION CONTROL
`IN THE NON-BRANCH MODE
`
`( RETURN )
`
`
`
`
`

`

`6,049,749
`
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`U.S. Patent
`
`Apr. 11, 2000
`
`Sheet 7 of 9
`
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`

`

`U.S. Patent
`
`Apr. 11, 2000
`
`Sheet 8 of 9
`
`6,049,749
`
`FIG. 11
`
`
`
`(INTERSECTION)
`
`
`
`(Y-SHAPED BRANCH)
`
`

`

`U.S. Patent
`
`Apr. 11, 2000
`
`Sheet 9 of 9
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`6,049,749
`
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`

`6,049,749
`
`1
`LIGHTING DEVICE FOR A VEHICLE
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`The present invention relates to a lighting device for
`vehicle use which conductsirradiation controlof the lighting
`device in accordance with a road profile, vehicle operation
`and vehicle running condition.
`2. Background
`there is known a device by which an
`Conventionally,
`irradiating direction of a lighting device for a vehicle is
`changed in accordance with a steering angle of the vehicle.
`In this type device, the following problems may be encoun-
`tered. As long as a steering member such as a steering wheel
`is not actually operated,
`the irradiating direction of the
`lighting device can not be changed. Therefore, it is impos-
`sible to adjust the irradiating direction of the lighting device
`into a direction in which the vehicle is advancing,just prior
`to a point in time at which the vehicle advances to a curved
`road.
`
`10
`
`15
`
`In order to solve the above problems, there is proposed a
`device in which the navigation system (route guidance
`system) is used and the irradiating direction ofthe lighting
`device for vehicle use is changed before the advance of the ,
`vehicle to a curved road in accordance with the map infor-
`mation including profile data of the road and also in accor-
`dance with the positional information of the vehicle on a
`map provided in the vehicle. However, the above device is
`disadvantageous in that the irradiation control can not be
`completely conducted when the vehicle is on a road which
`is not included in the map information and also when the
`vehicle advances to a route not scheduled at an intersection.
`
`30
`
`That is, when the navigation system can not be used or the
`vehicle advancing direction is changed at an intersection,
`priority is given to the driver’s intention.
`In order to solve the above problems, there is known a
`device in which priority is given to the irradiation control of
`the lighting device for vehicle use based on the operation of
`a direction indicator and the detection of a steering angle,
`over the irradiation control based on the map information.
`It is possible to conduct irradiation control of the lighting
`device irrespective of the navigation system in the following
`manner. For example, a signal sent out from a direction
`indicator of the vehicle is discriminated, and the irradiating
`direction of the lighting device is changed in a direction of
`a track to which the signal is indicated. Alternatively, there
`is provided a detecting meansfor detecting a steering angle,
`andthe irradiating direction ofthe lighting device is changed
`when a steering angle detected by the detecting meansis
`larger than a predetermined valuc.
`However, when the above methodis adopted, the follow-
`ing problems maybe encountered. Since priority is always
`given to the operation of the direction indicator of the
`vehicle and the result of detection of the steering wheel,
`when a driver mistakenly emits a signal of the direction
`indicator in an erroneous direction, the irradiating direction
`of the lighting device is changed in a direction at which the
`driver is not aiming. Also, whenpriority is excessively given
`to the detection of the detected steering angle, it become
`impossible to accomplish the primary object of changing the
`irradiating direction ofthe lighting device before the vehicle
`centers a curved road.
`
`SUMMARYOTFTIE INVENTION
`
`According to the present invention, the vehicle advancing
`direction at which a driver aimsis predicted, and irradiation
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`control of the lighting device is conducted by referring the
`result of prediction to the informationofthe profile of a road
`on which the vehicle is running at present.
`In order to solve the above problems, the present inven-
`tion is directed to a lighting device for vehicle use compris-
`ing: an irradiation control meansfor controlling the irradia-
`tion of a lighting device for vehicle use in accordance with
`aroadprofile, operation of the vchicle and running condition
`of the vehicle; a road profile calculating meansfor finding an
`advancing direction of the vehicle in the case where the
`vehicle advances along a road on which the vehicle is
`running at present, in accordance with the map information
`including the road profile and the present position informa-
`tion of the vehicle; and a vehicle advancing direction
`predicting means for predicting an advancing direction of
`the vehicle intended by a driver, by an operation signal given
`by the driver or detection information of the vehicle running
`state, wherein the irradiation control means compares the
`direction data of the road profile calculating means with the
`direction data of the vehicle advancing direction predicting
`means,
`the irradiation control of the lighting device is
`conducted by the road profile in accordance with the direc-
`tion data of the road profile calculating means when a
`difference between them is in an allowable range, and the
`irradiation control ofthe lighting device is conducted bythe
`direction data of the vehicle advancing direction predicting
`means whenthe difference between them is outside of the
`allowable range. According to the present invention, the
`direcuion data made by the road profile calculating meansis
`compared with the direction data made by the vehicle
`advancing direction predicting means. Due to the above
`comparison, whenthe vehicle advancing direction at which
`the driver aims coincides with the profile of a road, irradia-
`tion control of the lighting device is conducted in accor-
`dance the profile of the road. When the vehicle advancing
`direction at which the driver aims does not coincide with the
`profile of the road, it possible to conduct irradiation control
`of the lighting device in accordance with the vehicle advanc-
`ing direction at which the driver aims.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a block diagram showing the essential structure
`of the lighting device for vehicle use according to the present
`invention;
`VIG. 2 is a schematic illustration showing the selection of
`a tack at a branch on a road;
`FIG. 3 is a schematic illustration showing the irradiation
`angle of a lighting device on a straight road;
`FIG. 4 is a schematicillustration showing the irradiating
`angle of a lighting device at an intersection;
`FIG. 5 is a schematic illustration showing a relation
`betweenthe distance from the intersection to the vehicle and
`the irradiating angle;
`FIG. 6 is a view showing the first example of the present
`invention together with FIGS. 7 to 11, wherein this view is
`a block diagram showing the device structure;
`FIG. 7 is a schematic illustration showing the arrange-
`ment of a lighting device;
`FIG. 8 is a schematic illustration showing an example of
`the change in a luminous intensity distribution in a light
`distribution pattern;
`FIG. 9 is a flow chart showing a procedure in the
`interlocking mode of communication between road and
`vehicle;
`FIG. 10 is a schematic illustration for explaining irradia-
`tion control of a lighting device when a vehicle runs on a
`curved road;
`
`

`

`6,049,749
`
`3
`FIG. 11 is a schematic illustration of irradiation control
`conducted on a lighting device at a branch; and
`FIG. 12 is a circuit block diagram showing an arrange-
`ment of the device of the second example of the present
`invention.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`FIG. 1 is a view showing an essential structure of the
`lighting device 1 for vehicle use according to the present
`invention. The lighting device 1 includes: a road profile
`calculating means 2, vehicle advancing direction predicting
`means3, irradiation control means 4 and light device (e.g.,
`headlamp) 5. The irradiating direction and irradiating range
`of the lighting device 5 are directly controlled by the
`irradiating control means 4 or indirectly controlled via the
`drive means 6. In the case of a lighting device used for an
`automobile, examples of the lighting device 5 are a head
`lamp, fog lamp and corner lamp.
`The road profile calculating means 2 is provided for
`finding an advancing direction of a vehicle in the case where
`the vehicle advances along a road on which the vehicle is
`running at present in accordance with the map information
`including the road profile and the present position informa-
`tion of the vehicle. An output signal of the road profile
`calculating means 2 is sent to the irradiation control means
`4.
`
`Whenthe road map information is inputted, it is possible
`to use the navigation system, which is called “Car Naviga-
`tion System”, utilizing electric waves sent from GSP (Global
`Positioning System) satellite, and it is also possible to use
`the communication system for conducting communication
`between the road and vehicle. In the former navigation
`system, according to the detection signals of the gyrosensor
`and vehicle speed sensor, the electric wave information sent
`from GSPsatellite received by GSP receiver and the map
`information recorded on a recording medium such as
`CD-ROM, it is possible to display the present position of the
`vehicle on a road map, and it is also possible to guide the
`vehicle along a scheduled route to the destination. Accord-
`ing to the latter communication between the road and
`vehicle, information about the position of the vehicle and
`road profile (including a taper and radius of curvature of the
`road) can be obtained via beacons (poles used for commu-
`nication between the vehicles and road) which are arranged
`in central separation zones and road side zonesoftrunk lines
`at regular intervals and also arranged at primary corners and
`intersections in city areas and mountain areas in which many
`obstacles in correspondence are located.
`Further, a system in which the auxiliary channels of FM
`broadcasting multisystem is used can be adopted to input the
`road map information. As long as the road profile informa-
`tion and the present position information of the vehicle can
`be obtained, it is possible to find an advancing direction of
`the vehicle when the vehicle advances on the road and it is
`
`also possible to judge whether or not a branch such as an
`intersection is located ahead.
`
`The vehicle advancing direction predicting means pre-
`dicts an advancing direction of the vehicle at which the
`driver aims, by an operation signal given bythe driverof the
`vehicle or a detecting information of the vehicle running
`condition. The result of prediction is sent to the irradiation
`control means4.
`
`Examples of information used for predicting the vehicle
`advancing direction are: a direction indicating signal given
`to the direction indicator, detection signal of the steering
`
`10
`
`15
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`4
`angle (steering angle of the steering wheel), vehicle speed
`detection signal, acceleration detection signal, detection
`signal of the vehicle posture (output signal of the vehicle
`height sensor), and scheduled route to the destination that is
`set in the navigation system having a route guide function.
`According to the information described above, the vehicle
`advancing direction predicting means 3 synthetically pre-
`dicts a vehicle advancing direction at which the driver aims.
`For example, without relying only on the direction indicat-
`ing signal, a change in the steering angle is detected every
`moment from a point in time at which the direction indi-
`cating signal is sent out, and it is judged by a change in the
`vehicle posture, vehicle speed, vehicle acceleration and
`vehicle running condition whether or not a preliminary
`behavior to turn in a direction indicated by the direction
`indicating signal can be recognized, and the vehicle move-
`ment can be predicted. That
`is, when a change in the
`behavior is detected before the vehicle changesits track, and
`a direction extrapolated as an extension of the changein the
`behavior is discriminated as an advancing direction of the
`vehicle.
`
`An example of the prediction of the vehicle advancing
`direction is explained as follows using a simplified model.
`Concerning the direction indicator, a judgment of the right
`and left is conducted, and also it is detected whetheror not
`there is an indication given by the driver. A direction of the
`change in the steering angle is discriminated and also an
`amountof changein the steering angle is discriminated. ‘The
`direction of acceleration is discriminated and also an inten-
`
`sity of acceleration is discriminated. First, when a direction
`indicating signalis given, it is temporarily predicted that the
`advancing direction is to be changed in the direction con-
`ecrned. When the change in the steering angle in a predc-
`termined period of time is large or the vehicle speed is
`reduced exceeding a predetermined range, it is judged that
`the prediction is correct. When the change in the steering
`angle in a predetermined period of time is small or the
`vehicle speed is not
`reduced,
`the above prediction is
`corrected, and it is judged that the driver has no intention of
`changing the track. In the case where the change in the
`steering angle in a predetermined period oftimeis large or
`the vehicle speed is suddenly reduced although there is no
`direction indicating signal, it is judged that the driver has an
`intention of changing the tack. In this connection, concern-
`ing the importance of the basic information used for
`prediction, it is not necessary that all pieces of information
`must be uniform. Of course, in accordance with the value of
`information, it can be weighted.
`Whenthe vehicle advancing direction is predicted,it is
`possible to utilize information obtained from the above road
`profile data. For example, in the case of a road on which a
`branch is located ahead,a distance from the present vehicle
`position to the branch is calculated, and a change of the
`steering angle is detected as the distance is shortened. When
`the change of the steering angle is small, it can be predicted
`that the vehicle advancesstraight. When the change of the
`steering angle is large, it can be predicted that the driver has
`an intention of changing the track in the changing direction
`of the steering angle.
`Whenit is predicted that the vehicle advancing direction
`is the sameas the direction of the road on which the vehicle
`
`is running at present, the irradiation control means 4 con-
`ducts irradiation controlof the lighting device in accordance
`with the road profile. When it
`is discriminated that the
`predicted vehicle advancing direction is different from the
`direction of the road on which the vehicle is running at
`present, irradiation control of the lighting device 5 is con-
`
`

`

`6,049,749
`
`5
`ducted in accordance with the predicted vehicle advancing
`direction. That is, the irradiation control means 4 compares
`the direction data of the road profile calculating means 2
`with the direction data of the vehicle advancing direction
`predicting means 3. Whena difference between themts in an
`allowable range, irradiation control of the lighting device 5
`is conducted in accordance with the road profile based on the
`direction data of the road profile calculating means 2. When
`a difference between them is out of an allowable range,
`irradiation control of the lighting device 5 is conducted in
`accordance with the predicted vehicle advancing direction
`based onthe direction data of the vehicle advancing direc-
`tion predicting means 3.
`for
`Concerning the comparison of direction data,
`example, it is possible to use a method in whicha difference
`of the angle between two directions is compared with a
`reference value of judgment. Also, it is possible to use a
`method in which a predetermined angle widthis set for two
`angles and crossing of the two angles is compared with a
`reference value of judgment. Concerning the reference value
`and the angle width used in this case, they may be constant
`values, or alternatively they may be changed in accordance
`with other factors such as a vehicle speed.
`Whenit is discriminated that there is a branch ahead on
`a road, it is preferable to discriminate whether the driver
`wantsto select one ofthe plurality of selections at the branch
`or to advance to a track not included in the selectionsat the
`branch.
`
`10
`
`15
`
`For example, it is possible to consider a case shown in
`FIG. 2. In this case, branch P is located ahead on road Rt. At
`branch P, the road branchesinto roads A to D, wherein roads
`A to D shownbysolid lines are roads included in the map
`information, and road E (shownby a brokenline) is a road
`not included in the map information. Whenthe driver selects
`one of roads A to D at branch P, the road profile calculating
`means 2 sends four groups of data indicating the predicted
`vehicle advancing directionsto the irradiation control means
`4, and these groups of data are compared with the direction
`data sent from the vehicle advancing direction predicting
`means3. By this comparison,it is possible to select one of
`the tracks at branch P, because the driver may select a group
`of data, which is closest to the direction data sent from the
`vehicle advancing direction predicting means 3, from the
`four data groups sent from the road profile calculating means
`2. However, in the case where the driver selects road E not
`included in the map information, the four groupsofdirection
`data sent from the road profile calculating means 2 are not
`close to the direction data sent from the vehicle advancing
`direction predicting means 3. Accordingly, the irradiation
`control means 4 conducts irradiation control of the lighting
`device 5 in accordance with the direction data sent from the
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`vehicle advancing direction predicting means3 in this case.
`Whenthe branchis discriminated,it is possible to make
`judgmentindiscriminately, however,it is preferable to make
`judgment whetheror not it can be assumed to be a branch,
`in accordance with the scale of the branch. The branch may
`be discriminated as follows. For example,
`the following
`setting maybe adopted. Only an intersection provided with
`a signal machine is discriminated to be a branch,oralter-
`natively according to the grade of a road and the circum-
`stances of an intersection, only an intersection al which
`trunk roads such as national highways and state highways
`cross each other is discriminated to be a branch. When the
`
`branchis discriminated as described above, the driver may
`determine its setting by manual operation while a plurality
`of levels are set. Alternatively, discrimination may be auto-
`matically conducted by the vehicle in such a mannerthat
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`only a large scale intersection is discriminated to be a
`branch, for example, when the vehicle is running on a
`passing lane.
`Concerning the irradiation control, the following control
`factors are provided:
`(A)Irradiating direction
`(B) Irradiating range
`(C) Time to start control
`(D) Control speed
`First, concerning the control of the irradiating direction,
`the following two methods are provided:
`(A-I) Method of directing all of irradiation light
`predetermined direction; and
`(A-ID Methodof directing a portion ofirradiation light in
`a predetermined direction.
`The simplest method in the above item (A-D) is to direct
`an irradiation axis of the lighting device in a predetermined
`direction byrotating the entire lighting device aboutits axis.
`Another methodis to direct an irradiation axis ofthe lighting
`device in a predetermined direction by controlling the pos-
`ture of a member composing the lighting device such as a
`reflecting mirror, lens, light source and shielding member.
`According to the method described in item (A-ID), irra-
`diation light is changed partially. Accordingly,it is possible
`to adopt a method in which the irradiation axis of only a
`specific lighting device is changed in the device composed
`of a plurality of lighting devices. For example, in an auto-
`mobile provided with head lamps, fog lamps and corner
`lamps,
`the posture of the irradiation axis of one of the
`lighting devices or the postures of the irradiation axes of two
`of the lighting devices are controlled. Alternatively,
`it is
`possible to adopt a mcthod of controlling the posture of onc
`of the members composing the lighting device or the pos-
`tures of a plurality of members composing the lighting
`device. For example, the reflecting mirror is composed of a
`stationaryreflecting mirror and a movablereflecting mirror,
`and the optical axis of the movable reflecting mirror is
`directed to a predetermined direction.
`Concerning the irradiating range control described in the
`above item (B), the following two methods are provided:
`(B-1) Mcthodin whichtheirradiating ranges of a plurality
`of lighting devices are combined with each other; and
`(B-2) Method of changing anirradiating range by moving
`a portion of the components of the lighting device.
`First, the method described in item (B-1) is a method of
`controlling the irradiation range of a portion of lighting
`devices in which the overall irradiation range is formed by
`combining the irradiation ranges of a plurality of lighting
`devices. For example,
`there are provided two lighting
`devices, the irradiation ranges of which are different from
`each other, in a vehicle. The irradiation range of one of the
`lighting devices is fixed, and the irradiation range of the
`other lighting device is changed, for example, the irradiation
`range is extended in the transverse direction.
`According to the above method, when someof the plu-
`rality of lighting devices, the irradiation ranges of which are
`different from eachother, are selected, it is possible to obtain
`a desired irradiating range. However,it is necessary to use
`a large-scale device in the above method. For this reason,
`whenil is necessary to simplify the structure of the device,
`the method of item (B-2) is preferably used.
`That is, when one of the members composing the lighting
`device or some members composing, the lighting device are
`changed in the posture, it is possible to change the irradi-
`ating range ofthe lighting device. For example, as a method
`of utilizing the movementsoflenses, two lenses are arranged
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`so that the relative positional relation of the two lenses can
`adjusted, and diffusion of irradiating light is freely con-
`trolled whenthe lens drive is controlled. Also,it is possible
`to adopt a method in which the irradiating range of the
`lighting device is changed when a shade provided for
`shading a portion of light emitted from a light source is
`moved. Also,
`the following various methods may be
`adopted. Only the light source is moved,
`the reflecting
`mirror and light source are moved, the lens and reflecting
`mirror are moved, or the lens and shade are moved together
`so that the irradiating range can be changed. It is possible to
`adopt various embodiments in accordance with the combi-
`nation of the optical composing members of the lighting
`device.
`In this connection, concerning the control of extending
`and reducing the irradiating range,it is preferable to change
`the irradiating range in accordance with the speed and
`acceleration of the vehicle. The reason is that the range of
`vision ofa driveris different between the case of high speed
`driving and the case of low speeddriving, and also the range
`of vision ofa driver is different between the case of constant
`speed driving and the case of reduced speed driving. It is
`preferable that the irradiating range is extended in the cases
`of low speed driving and sharply reduced speed driving as
`compared with other cases.
`Concerningthestart time of control described in item(C),
`for example, in the case of a road having a branch, it is
`judged whether or not a distance from the branch to the
`vehicle or a time obtained when the distance is divided by
`a vehicle speed is in a predetermined range. It is possible to
`determine a point in time to start irradiation control such as
`a changeofthe irradiating direction ox irradiating range in
`accordance with the result of judgment. In this case, it is
`preferable that the reference value be changed in accordance
`with the vehicle speed and/or acceleration, because the way
`of access to a branch is different according to the vehicle
`speed. For example, when the vehicle speed is high,
`the
`irradiating range of the vehicle is changed at a position
`distant from the branch,or alternatively the irradiating range
`is changed early when the track of the vehicle is changed.
`The higher the acceleration in the negative direction is, the
`earlier the changing time of the irradiating range is made.
`In this connection, concerning the detection of the vehicle
`speed, a detection signal obtained by the vehicle speed
`detecting means 7 maybesentto the irradiating means4 as
`shown in FIG. 1. Concerning the detection of the vehicle
`acceleration, it is possible to adopt a method in which an
`acceleration sensor is provided, and also it is possible to
`adopt a method in which the vehicle speed detected by the
`vehicle speed detecting means7 is differentiated by the time.
`Control speed described in item (D) is a changing speed
`in the case of controlling the irradiating direction and
`irradiating range. It is preferable that the control speed be
`changed in accordance with the vehicle speed and/or vehicle
`acceleration. The reason is that there is a possibility that the
`irradiating control can not follow a change in the vehicle
`speed when the control speed is maintained constant.In this
`connection, concerning the control of a controlling speed,
`for example, it is possible to adopt a method in which the
`responding speed of the drive means6 is changed. There are
`various types of specific controlling methods. For example,
`the speed of posture control of the entire lighting device or
`the members composing the lighting device can be changed
`by changing a voltage and electric current supplied to the
`actuator composing the drive means 6 and also by changing
`a pulse width of the control signal and a duty cycle.
`The irradiating control means 4 conducts controlling for
`the above items (A) to (D). Basic information used for
`control include:
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`(a) Information about whether or not there is a branch on
`a road, and distance or time to the branch;
`(b) Operation signal give by a driver, and detection
`information of the vchicle running condition; and
`(c) Information about whether or not road profile data is
`provided.
`First, concerning the above item (a), operation is per-
`formed as follows. Irradiation control is changed according
`to whether ornot there is a branch (intersection) ahead on a
`road. In the case where there is a branch on the road, the
`irradiating range is changed in accordance with the distance
`from the branch to the vehicle and the time obtained when
`the distance is divided by the vehicle speed. For example,
`the irradiating range is changedas follows. As shownin FIG.
`3, “a0”is a horizontal irradiating angle with respect to the
`wradiating range of the lighting device when vehicle K is
`