(19) Japan Patent Office (JP)
`
`(11) Patent Application
`(12) PATENT
`APPLICATION PUBLICATION (A)
`
`
`
`
`Publication No.
`H7-164960
`
`
`
`(51) Int. Cl.6 Ident. Code
` B60Q 1/12
`
`
`(43) Publication Date June 27, 1995 (Heisei 7)
`Inter. Ref. No.
`FI
`Location of Tech. Indication
`
`
` B60Q 1/12
`
`B
`
`
`
`Examination Request: Not Made Total No. of Claims: 1 OL (Total 10 pages)
`(71) Applicant
`000003207
`(21) Application No. H5-318586
`
`Toyota Motor Corporation
`
`
`1 Toyota-cho
`December 17, 1993
`(22) Date of Filing
`
`Toyota-shi, Aichi-ken
` (Heisei 5)
`(72) Inventor
`Takakazu Mori
`
`c/o Toyota Motor Corporation
`
`1 Toyota-cho
`
`Toyota-shi, Aichi-ken
`(72) Inventor
`Takashi Nakamura
`
`c/o Toyota Motor Corporation
`
`1 Toyota-cho
`
`Toyota-shi, Aichi-ken
`(72) Inventor
`Hisashi Satonaka
`
`c/o Toyota Motor Corporation
`
`1 Toyota-cho
`
`Toyota-shi, Aichi-ken
`(74) Agent
`Atsushi Nakajima,
`
`Patent Attorney (and two others)
`Continued on Last Page
`
`
`
`
`
`1
`
`1
`
`SL-1010
`
`

`
`(54) [Title of Invention] Vehicle headlamp device
`
`(57) [Abstract]
`[Purpose] To ensure an optimal field of vision of
`a driver despite an attitude change of a vehicle
`due to a vehicle speed or the like.
`[Constitution] When a brake is OFF, normal light
`distribution control is performed (302, 304, 310).
`When the brake is ON (306, 308), a current
`vehicle speed of a vehicle 10 is read (312), and a
`brake pedal depression speed is detected by a
`brake depression speed sensor (314). An attitude
`displacement amount of the vehicle 10
`corresponding to the vehicle speed and the brake
`pedal depression speed is predicted by
`referencing a map (316). When the predicted
`attitude displacement amount exceeds a setting
`value (318), a stored optical axis control amount
`is read (320), a corrective optical axis control
`amount is calculated from the optical axis
`control amount according to the vehicle speed
`and the predicted attitude displacement amount
`(322), and an optical axis of the headlamp is
`deflected according to the calculated corrective
`optical axis control amount (324).
`
`
`
`
`
`
`
`2
`
`2
`
`

`
`[Claims]
`[Claim 1] A vehicle headlamp device, comprising:
`a vehicle speed sensor that detects a vehicle speed of a vehicle having a headlamp that can control
`at least a brightness, an irradiation direction, or an irradiation range;
`an operation amount detection means that detects an operation amount of the vehicle;
`an attitude change amount prediction means that predicts an attitude change amount of the vehicle
`based on the vehicle speed and the operation amount; and
`a control means that controls at least the brightness, the irradiation direction, or the irradiation
`range of the headlamp based on the predicted attitude change amount.
`[Detailed Description of Invention]
`[0001]
`[Industrial Field of Application] The present invention relates to a vehicle headlamp device and
`specifically relates to a vehicle headlamp device that controls a light distribution of a headlamp
`that irradiates an area in front of a vehicle.
`[0002]
`[Conventional Art] With vehicles, a headlamp is provided at approximately a leading edge of a
`vehicle to improve a visibility of an area in front of a driver at night or the like. Recently, there are
`vehicle forward illumination devices that change an irradiation optical axis and an irradiation
`range of a headlamp according to a steering angle or the like for ensuring a field of vision of a
`driver (JPS55-22299B2, JPH2-27938U, JPH1-293247A, and the like).
`[0003] Incidentally, a gaze position of the driver changes when a vehicle speed or the vehicle
`accelerates or decelerates. That is, the driver views an area farther away when the vehicle is
`accelerating and views an area more nearby when decelerating. Because of this, to ensure the field
`of vision, there is a need to change irradiation states such as the irradiation optical axis and the
`irradiation range of the headlamp according to the acceleration or the deceleration of the vehicle
`speed or the vehicle. Because of this, there is a headlamp irradiation angle adjustment device as a
`vehicle headlamp device that changes an irradiation angle of a headlamp to an appropriate
`irradiation angle by detecting acceleration and deceleration and ensuring a field of vision that is
`farther away when accelerating and ensuring a field of vision that is more nearby when
`decelerating (JPS63-131839U).
`[0004]
`[Problem to be Solved by Invention] However, the vehicle gives rise to an attitude change (a
`so-called “squat”) that raises a front part of the vehicle when accelerating and gives rise to an
`attitude change (a so-called “dive”) that raises a rear part of the vehicle when decelerating.
`Because of this, if the irradiation angle of the headlamp is changed to the appropriate irradiation
`angle to ensure the field of vision of the driver by the conventional vehicle headlamp device when
`the vehicle is accelerating or decelerating as above, the irradiation angle of the headlamp is
`changed so as to irradiate an area farther away than the appropriate irradiation angle due to
`squatting when accelerating and the irradiation angle of the headlamp is changed so as to irradiate
`an area even more nearby than the appropriate irradiation angle due to diving when decelerating.
`In this manner, there is a problem where an area in front of the vehicle cannot be appropriately
`irradiated by a light of the headlamp due to the attitude changes of the vehicle.
`[0005] In consideration of the facts above, the present invention has as an object to obtain a vehicle
`headlamp device that can ensure an optimal field of vision of a driver despite an attitude change of
`a vehicle due to a vehicle speed or the like.
`
`
`
`3
`
`3
`
`

`
`[0006]
`[Solution to Problem] To achieve the object above, a vehicle headlamp device of the present
`invention is provided with a vehicle speed sensor that detects a vehicle speed of a vehicle having a
`headlamp that can control at least a brightness, an irradiation direction, or an irradiation range; an
`operation amount detection means that detects an operation amount of the vehicle; an attitude
`change amount prediction means that predicts an attitude change amount of the vehicle based on
`the vehicle speed and the operation amount; and a control means that controls at least the
`brightness, the irradiation direction, or the irradiation range of the headlamp based on the predicted
`attitude change amount.
`[0007]
`[Operation] According to the present invention, the headlamp of the vehicle can control at least the
`brightness, the irradiation direction, or the irradiation range. The vehicle speed of this vehicle is
`detected by the vehicle speed sensor. The operation amount detection means detects the operation
`amount of the vehicle. As this operation amount of the vehicle, there is a depression position of a
`brake pedal, a depression speed, a throttle opening, a rising speed of a brake fluid pressure, a
`steering angle, a steering angle speed, and the like. The attitude change amount prediction means
`predicts the attitude change amount of the vehicle based on the vehicle speed and the operation
`amount. Note that with the attitude change amount of the vehicle, an attitude change amount from
`a reference attitude of the vehicle may be obtained. With this reference attitude, there is an attitude
`of the vehicle when running on level ground at a constant speed as well as a situation of being
`offset according to a carried load of the vehicle. Here, an attitude of the vehicle changes greatly if
`a change in the vehicle speed is sudden but changes little if the change in the vehicle speed is slow.
`This change of the vehicle speed can be determined according to an operation indication amount of
`the driver by the depression position or the depression speed of the brake pedal. Therefore, if the
`control means controls at least the brightness, the irradiation direction, or the irradiation range of
`the headlamp based on the attitude change amount of the vehicle predicted based on the vehicle
`speed and the operation amount by the attitude change amount prediction means, the optimal field
`of vision of the driver can be ensured even if an attitude change of the vehicle occurs. For example,
`when accelerating, an attitude change amount where a front part of the vehicle rises can be
`predicted, and when decelerating, an attitude change amount where a rear part of the vehicle rises
`can be predicted. Because of this, when controlling at least the brightness, the irradiation direction,
`or the irradiation range of the headlamp, because at least one control amount from among the
`brightness, the irradiation direction, or the irradiation range to be controlled increases when the
`attitude change of the vehicle is predicted by the vehicle speed and the operation amount, it is
`favorable to control at least the brightness, the irradiation direction, or the irradiation range of the
`headlamp so as to offset this control amount that increases.
`[0008] Note that the control means may control the headlamp so at least the brightness, the
`irradiation direction, or the irradiation range of the headlamp in the predicted attitude change
`amount corresponds to at least the brightness, the irradiation direction, or the irradiation range in
`the reference attitude of the vehicle. In this situation, the attitude of the vehicle may be controlled
`by assuming a change in the attitude beyond the reference attitude.
`[0009] Furthermore, because the attitude change amount of the vehicle is different with every
`vehicle due to suspension geometries and suspension properties, it is favorable to predict the
`attitude change amount of the vehicle in consideration of the suspension geometry and the
`
`
`
`4
`
`4
`
`

`
`suspension property. By doing so, an individual optimal attitude change amount can be predicted
`for each vehicle.
`[0010]
`[Examples] Examples of the present invention will be described in detail below by referencing the
`drawings. A vehicle headlamp device of the present example is one where the present invention is
`applied to a situation of controlling a light distribution by a front headlamp of a vehicle 10 by
`deflecting an irradiation optical axis of the headlamp. As illustrated in FIG. 1, an engine hood 12 is
`disposed on an upper face portion of a front body 10A of the vehicle 10, and a front bumper 16 is
`fixed to both end portions in a vehicle width direction of a front end portion of the front body 10A.
`Headlamps 18, 20, which are a lateral pair (both end portions in the vehicle width direction), are
`disposed on an upper portion of this front bumper 16 and a lower portion of the front body 10A.
`[0011] Furthermore, a windshield glass 14 is provided near a rear end portion of the engine hood
`12. A room mirror 15 is provided in an upper portion of this window shield glass 14 and inside the
`vehicle 10, and a TV camera 22 that includes a nighttime detection optical system for taking
`images of an area in front of the vehicle is disposed near this room mirror 15. This TV camera 22 is
`of a configuration that can also take images of a dark portion in front of the vehicle while running
`at night by having a photomultiplier tube or the like and amplifying a weak light. The TV camera
`22 is connected to an image processing device 48 (FIG. 4). The image processing device 48 is a
`device that image processes an image taken by the TV camera 22 based on signals input from the
`TV camera 22 and a control device 50. Note that a disposition position of the TV camera 22 is
`preferably positioned near a viewing position (a so-called “eye point”) of the driver so as to enable
`accurately recognizing a road shape in front of the vehicle and so as to better match a visual
`sensation of the driver. Note that the road shape above includes a road shape corresponding to a
`shape of a path of travel, for example, one lane formed by a centerline, a curb, and the like.
`[0012] A speed meter that is not illustrated is disposed in the vehicle 10, and a vehicle speed sensor
`66 (FIG. 4) that detects a vehicle speed V of the vehicle 10 is installed on a cable that is not
`illustrated of this speed meter that is not illustrated. Moreover, on a brake pedal (illustration
`omitted) provided in the vehicle 10, a brake switch 74 that turns on when the brake pedal that is not
`illustrated is depressed is installed and a brake depression speed sensor 70 (FIG. 4) that detects a
`depression speed BV of the brake pedal that is not illustrated is installed. Note that the brake
`depression speed may be a rising speed of a brake fluid. Moreover, an accelerator switch 72 that
`turns on when a predetermined opening, which corresponds to an accelerator pedal being
`depressed, is reached or exceeded and an accelerator depression speed sensor 68 (FIG. 4) that
`detects a depression speed AV of the accelerator pedal that is not illustrated by detecting an
`opening and closing speed of a throttle bulb that is not illustrated are installed on a throttle bulb
`(illustration omitted) that regulates a flow rate of fuel.
`[0013] As illustrated in FIG. 2, the headlamp 18 is a headlamp of a projector type and has a convex
`lens 30, a bulb 32, and a lamp housing 34. The convex lens 30 is fixed in one opening of this lamp
`housing 34, and the bulb 32 is fixed in another opening thereof via a socket 36 so a luminous point
`is positioned on an optical axis C of the convex lens 30 (center axis of the convex lens 30).
`[0014] A bulb side inside the lamp housing 34 is made to be a reflector 38 of an ellipsoidal
`reflective surface, and a light from the bulb 32 reflected by this reflector 38 is condensed between
`the convex lens 30 and the bulb 32. An upper end of a shade 40 (see FIG. 3) is fixed so as to be
`positioned near this condensing point. A shape of this shade 40 is determined in advance for driver
`visibility improvement of a pedestrian, a sign, and the like and for preventing glaring to an
`
`
`
`5
`
`5
`
`

`
`opposing vehicle, and the light from the bulb 32 reflected and condensed by the reflector 38 is
`emitted from the convex lens 30 by being divided into a transmitted light and a blocked light by the
`shield 40.
`[0015] Furthermore, a bearing 42 is fixed to an upper portion front part 34A of the lamp housing
`34. This bearing 42 is axially supported by a strut 44. This strut 44 is fixed horizontally to a frame
`that is not illustrated of the vehicle 10. Moreover, a cylindrical tip of a mover 46A of an actuator 46
`is installed on a lower portion rear part 34B of the lamp housing 34. This actuator 46 is fixed to the
`frame that is not illustrated of the vehicle 10 and is configured from a motor 46D and a worm gear
`that has the mover 46A as a worm. That is, a rear end of the mover 46A is carved so as to function
`as the worm and is engaged to a worm wheel 46B. This mover 46A is made to be linearly movable
`by a sliding mechanism that is not illustrated, a rotational axis of the worm wheel 46B is fixed to a
`shaft 46C of the motor 46D, and a rotation of the motor 46D is converted into a linear drive of the
`mover 46A. Therefore, the mover 46A extends and contracts in a vertical direction (arrow A
`direction in FIG. 2) due to the rotation of the motor 46D according to the signal from the control
`device 50. When the mover 46A contracts, the headlamp 18 rotates to the left and the optical axis C
`becomes an optical axis CU, and when the mover 46A extends, the headlamp 18 rotates to the right
`and the optical axis C becomes an optical axis CD. In this manner, the headlamp 18 rotates with the
`strut 44 as an axis according to the extension and contraction of the mover 46A, and the optical
`axis C is deflected in a vertical direction (in the UP or DN direction in FIG. 1).
`[0016] The headlamp 20 is provided with a shade 41 and an actuator 47 (see FIG. 4). Because a
`configuration of the headlamp 20 is similar to that of the headlamp 18, a detailed description
`thereof will be omitted.
`[0017] As illustrated in FIG. 4, the control device 50 is configured including a read-only memory
`(ROM) 52, a random access memory (RAM) 54, a central processing unit (CPU) 56, an input port
`58, an output port 60, and a bus 62 such as a data bus or a control bus that connects the above. Note
`that a map (FIGS. 5, 6), a control program, and the like that will be described below are stored in
`this ROM 52.
`[0018] The vehicle speed sensor 66, the accelerator depression speed sensor 68, the brake
`depression speed sensor 70, the accelerator switch 72, the brake switch 74, and the image
`processing device 48 are connected to the input port 58. The output port 60 is connected to the
`actuators 46, 47 via the driver 64. Moreover, the output port 60 is also connected to the image
`processing device 48.
`[0019] Here, a gaze position of the driver is displaced according to the vehicle speed V. That is, the
`driver gazes near a position to which the vehicle arrives after a predetermined amount of time
`according to the vehicle speed V. Because of this, if the optical axis C is raised up and down
`according to the vehicle speed V, a region sufficient for the driver to view can be irradiated by the
`headlamp. A relationship between this vehicle speed V and an irradiation angle Lθ formed by the
`optical axis C for irradiating a vicinity of the gaze position can be represented by Formula (1)
`below. Once this irradiation angle Lθ is determined, the actuator can be driven so as to correspond
`to the irradiation angle Lθ.
`[0020]
`Lθ = Ls + f(V)———(1)
`wherein, Ls: Angle of reference optical axis (angle of reference optical axis C relative to level
`ground)
`f(V): Function for determining irradiation angle according to vehicle speed
`
`
`
`6
`
`6
`
`

`
`[0021] Note that the function f(V) can also be expressed as f(V)=μ·V. In this situation, μ is a
`constant, a linear constant whose increment value is determined proportionally to the vehicle
`speed V, or a non-linear constant whose increment value is determined in correspondence with the
`vehicle speed V.
`[0022] In the present example, the relationship defined by Formula (1) above is stored as a map in
`ROM 52. Note that by setting the vehicle speed V in a stepwise manner for each predetermined
`range instead of deflecting the optical axis C continuously according to the vehicle speed V, an
`optical axis drive control is simplified and a load on the control device can be mitigated. Moreover,
`the function f(V) includes signs; upward deflection from the reference optical axis C is made to
`correspond to a positive sign (+), and downward deflection is made to correspond to a negative
`sign (−).
`[0023] With the attitude of the vehicle 10, diving occurs when decelerating and squatting occurs
`when accelerating. If a change of the irradiation optical axis due to this attitude change of the
`vehicle is offset, the region sufficient for the driver to view can be irradiated by the headlamp even
`when accelerating or decelerating. The attitude change amount of the vehicle due to this diving or
`squatting corresponds to a degree of acceleration or deceleration. An attitude change amount L of
`the vehicle during squatting is determined by the accelerator pedal depression speed VA
`corresponding to the vehicle speed V and the degree of acceleration and can be represented by
`Formula (2) below. Moreover, an attitude change amount K of the vehicle during diving is
`determined by the brake pedal depression speed VB corresponding to the vehicle speed V and the
`degree of deceleration and can be represented by Formula (3) below.
`[0024]
`L = JA(V, AV)———(2)
`K = JB(V, BV)———(3)
`wherein, JA(V, AV): Function for determining attitude change amount according to vehicle speed
`and accelerator pedal depression speed
`JB(V, BV): Function for determining attitude change amount according to vehicle speed and brake
`pedal depression speed
`[0025] With the present example, the relationship between the vehicle speed V and the accelerator
`pedal depression speed AV is stored in the ROM 52 as a map A, and the relationship between the
`vehicle speed V and the brake pedal depression speed BV is stored as a map B in the ROM 52.
`Note that because the maps A and B stored in the ROM 52 perform the optical axis drive control in
`a stepwise manner for the sake of simplification instead of continuously deflecting the optical axis
`in correspondence with the vehicle speed V and the degree of acceleration or deceleration, they
`divide the accelerator pedal depression speed AV and the brake pedal depression speed BV into a
`plurality of stages and set the attitude displacement amounts K, L for each predetermined range.
`[0026] That is, as illustrated in FIG. 5, with the map B of the brake pedal depression speed, the
`vehicle speed V from 0 to a maximum speed MAX (for example, 180 km/h) is divided into four
`stages of 0 ≤ V < MAX/4, MAX/4 ≤ V < 2MAX/4, 2MAX/4 ≤ V < 3MAX/4, and 3MAX/4 ≤ V <
`MAX, and the brake pedal depression speed BV from 0 to a maximum depression speed FULL is
`divided into five stages of 0 ≤ BV < FULL/5, FULL/5 ≤ BV < 2FULL/5, 2FULL/5 ≤ BV <
`3FULL/5, 3FULL/5 ≤ BV < 4FULL/5, and 4FULL/5 ≤ BV < FULL. An attitude displacement
`amount Kn is set in each divided range. This attitude displacement amount Kn is a constant
`determined from a brake force of a front wheel and a rear wheel of the vehicle, an anti-diving
`suspension geometry of a suspension of the vehicle, a pitch rate of the vehicle (wheelbase distance
`
`
`
`7
`
`7
`
`

`
`or distance from a center of gravity of the vehicle to the headlamp), and the like, and an
`experimentally obtained value may be used. Moreover, an average value of the attitude
`displacement amounts in each range above may be used.
`[0027] Furthermore, as illustrated in FIG. 6, with the map A of the accelerator pedal depression
`speed, the vehicle speed V is divided into four stages, similar to the map B, and the accelerator
`pedal depression speed AV from 0 to a maximum speed FULL is divided into five stages of 0 ≤
`AV < FULL/5, FULL/5 ≤ AV < 2FULL/5, 2FULL/5 ≤ AV < 3FULL/5, 3FULL/5 ≤ AV <
`4FULL/5, and 4FULL/5 ≤ AV < FULL. An attitude displacement amount Ln (an experimentally
`obtained value, for example, an average value) is set in each divided range. This attitude
`displacement amount Ln is a constant determined from the suspension geometry of the vehicle, the
`pitch rate of the vehicle, and the like, and an experimentally obtained value may be used. Moreover,
`an average value of the attitude displacement amounts in each range above may be used.
`[0028] Actions of the present example will be described below. First, the driver turns on a light
`switch that is not illustrated of the vehicle to light the headlamps 18, 20, and a control main routine
`illustrated in FIG. 7 is executed at predetermined times. Once the main control routine is executed,
`the process proceeds to step 202, and after reading the vehicle speed V, at step 204, the maps above
`(see Formula [1]) are referenced to calculate the irradiation angle Lθ for irradiating the region
`(sufficient for the driver to view) corresponding to a current vehicle speed V and calculate a
`movement amount S (optical axis control amount S) of the actuators 46, 47 corresponding to the
`irradiation angle Lθ. At this step 204, the calculated optical axis control amount S is stored in the
`RAM 54. At step 206 that follows, the stored optical axis control amount S is read and the
`actuators 46, 47 are driven by only the read optical axis control amount S to deflect the optical axes
`of the headlamps 18, 20, thereby finishing the present routine.
`[0029] Therefore, the optical axis C is deflected near the gaze position of the driver, which is
`displaced according to the vehicle speed V, and the region sufficient for the driver to view is
`irradiated by lights of the headlamps. By this, visibility increases for the driver.
`[0030] Here, a situation where it is expected that the vehicle 10 will be displaced in attitude by the
`brake pedal or the accelerator pedal being depressed will be described with reference to FIGS. 8
`and 9.
`[0031] At predetermined times, a dive correction interruption control routine of FIG. 8 is executed,
`and at step 302, by reading an ON/OFF of the brake switch 74, a brake signal (ON of the brake
`switch 74) is read. When the brake switch 74 is OFF, a negative determination is made at step 304,
`the process proceeds to step 310 that follows, and a flag FLAG_B is reset, thereby finishing the
`present routine. This flag FLAG_B represents an ON/OFF state of a brake; when set (set to “1” in
`the present example), it represents that the brake is in an ON state, and when reset (set to “0” in the
`present example), it represents that the brake is in an OFF state.
`[0032] When the brake switch 74 is ON, a positive determination is made at step 304 that follows,
`and when the flag FLAG_B is reset (positively determined at step 306), the flag FLAG_B is set
`(step 308), and the process proceeds to step 312. At step 312, the current vehicle speed V of the
`vehicle 10 is read, and at step 314 that follows, the brake depression speed sensor 70 is read and the
`brake pedal depression speed BV is detected. At step 316 that follows, by reading the attitude
`displacement amount Kn corresponding to the read vehicle speed V and the brake pedal depression
`speed BV by referencing the map B illustrated in FIG. 5, the attitude displacement amount of the
`vehicle 10 is predicted.
`
`
`
`8
`
`8
`
`

`
`[0033] At step 318 that follows, it is determined whether a predetermined setting value β is
`exceeded, and when the attitude displacement amount Kn is at or below the setting value β, the
`present routine is finished. This setting value β can be determined experimentally so as to allow a
`normal attitude displacement amount in the vehicle while running at a constant speed. Meanwhile,
`when the attitude displacement amount Kn exceeds the setting value β, the process proceeds to
`step 320, the optical control amount S stored in the RAM is read, and the process proceeds to step
`322. At step 322, a corrective optical axis control amount dS is calculated by seeking a degree of
`deflection of the optical axis by the attitude displacement amount Kn predicted from the optical
`axis control amount S according to the read vehicle speed V. At step 324 that follows, the actuators
`46, 47 are driven from the optical control amount S only by the calculated corrective optical axis
`control amount dS and a corrective control that deflects the optical axes of the headlamps 18, 20 is
`performed, thereby finishing the present routine.
`[0034] Next, a situation where the vehicle attitude displacement due to the accelerator pedal being
`depressed is corrected will be described. At predetermined times, a squat correction interruption
`control routine of FIG. 9 is executed, and at step 402, an ON/OFF of the accelerator switch 72 is
`read. When the accelerator switch 72 is OFF, a flag FLAG_A is reset (step 410), thereby finishing
`the present routine. This flag FLAG_A represents an ON/OFF state of the accelerator; when set
`(set to “1” in the present example), it represents that the accelerator is in an ON state, and when
`reset (set to “0” in the present example), it represents that the accelerator is in an OFF state.
`[0035] When the accelerator switch 72 is ON, a positive determination is made at step 404 that
`follows, and when the flag FLAG_A is reset (positively determined at step 406), the flag FLAG_A
`is set (step 408), and the process proceeds to step 412. At step 412, the current vehicle speed V of
`the vehicle 10 is read, and at step 414 that follows, the accelerator depression speed sensor 68 is
`read and the accelerator pedal depression speed AV is detected. At step 416 that follows, by
`reading the attitude displacement amount Ln corresponding to the read vehicle speed V and the
`accelerator pedal depression speed AV by referencing the map A illustrated in FIG. 6, the attitude
`displacement amount of the vehicle 10 is predicted.
`[0036] At step 418 that follows, it is determined whether a predetermined setting value α is
`exceeded, and when the attitude displacement amount Ln is below the setting value α, the present
`routine is finished. This setting value α can be determined experimentally so as to allow the normal
`attitude displacement amount in the vehicle while running at the constant speed. Meanwhile, when
`the attitude displacement amount Ln exceeds the setting value α, the process proceeds to step 420,
`the optical control amount S stored in the RAM is read, and the process proceeds to step 422. At
`step 422, the corrective optical axis control amount dS is calculated by seeking the degree of
`deflection of the optical axis by the attitude displacement amount Ln predicted from the optical
`axis control amount S according to the read vehicle speed V. At step 424 that follows, the actuators
`46, 47 are driven from the optical control amount S only by the calculated corrective optical axis
`control amount dS and the corrective control that deflects the optical axes of the headlamps 18, 20
`is performed, thereby finishing the present routine.
`[0037] In this manner, in the present example, even in a situation where, when the driver depresses
`the accelerator pedal, it is predicted that an attitude displacement where a front part of the vehicle
`floats up and a rear part sinks (squatting) will occur or in a situation where, when the driver
`depresses the brake pedal, it is predicted that an attitude displacement where the front part of the
`vehicle sinks and the rear part floats up (diving) will occur, because the map is referenced from the
`vehicle speed and the accelerator pedal depression speed or the vehicle speed and the brake pedal
`
`
`
`9
`
`9
`
`

`
`depression speed, the corresponding attitude displacement amount is predicted, and the optical
`axis of the headlamp is deflected and controlled so as to offset the displacement of the optical axis
`due to the predicted attitude displacement amount, the optical axis of the headlamp corresponds to
`a normal irradiation optical axis and a field of vision of the driver can be ensured.
`[0038] Furthermore, because the optical axis of the headlamp is deflected so as to offset the
`predicted attitude displacement amount of the vehicle, a forward field of vision relative to the
`driver can be ensured before the attitude of the vehicle is displaced, thereby improving safety.
`[0039] Furthermore, in the present example, because threshold values that determine whether the
`attitude displacement amount of the vehicle used for corrective control exceeds the predetermined
`values α, β is set, with minute attitude fluctuations, no corrective control is performed, rendering a
`normal optical axis, which enables light distribution control without making the driver feel
`uncomfortable.
`[0040] In the example above, a light distribution control for ensuring the field of vision by the gaze
`position of the driver that is displaced according to the vehicle speed is described, but as another
`example, the gaze position of the driver is displaced according to the road shape such as a linearity
`and a gradient of the road. Even in this situation, the attitude of the vehicle changes according to
`the acceleration and deceleration of the vehicle. This gaze position of the driver according to the
`road shape can be estimated using the image processing device 48. If the irradiation direction or
`the irradiation range of the headlamp is changed according to an estimated gaze position, a field of
`vision of the driver according to the road shape such as the linearity and the gradient of the road
`can be ensured. An example of this image processing will be described simply. Note that with each
`pixel in the image formed by the image signal, a position can be specified by coordinates (Xn, Yn)
`of a coordinate system defined by an x-axis and a y-axis orthogonal to each other set in the image
`(see FIG. 10).
`[0041] A reference image 120 that substantially matches an image that the driver views when the
`TV camera 22 takes an image of a flat road 122 on which the vehicle 10 is running is illustrated
`(see FIG. 10). This road 122 has two lanes, and each lane has a centerline 124 as a boundary and
`has a curb 126 and the road 122 as other boundaries. In the image 120, a point D (XD, YD) of a
`position corresponding to an eye of a line of sight when the driver views in a forward direction
`parallel to the running direction of the vehicl