JPS6355455B2 - - Google Patents

Abstract

PURPOSE:To prevent the generation of angular differences between the left and the right optical axis by providing a means for initializing optical axes of two headlights in a change-over circuit which specifically connects 2 drive motors for adjusting optical axis with a power source. CONSTITUTION:A relay RL1 is excited by a comparator COM1 which generates an output when the voltage VD of an optical axis detector VR2 of a headlight 1 is smaller than the voltage VS of an optical axis setting unit VR1 corresponding to the rotation of a knob, etc. and another relay RL2 is excited by another comparator COM2 which generates an output when the voltage VD is larger than the voltage VS by a specified amount, and the relays RL1, RL2 are connected to drive motors ML, MR of the left and right headlights 1. A transistor Q4 of an initializing circuit INT is connected to a movable element S of the setting unit VR1 and a capacitor C1 is connected to an ignition switch SW. Since the movable element S maintains a ground potential for a specified period of time after the switch SW is closed, the left and right headlights 1 are tilted to the lower limits.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical axis adjustment device for a vehicle headlamp,
In particular, it is an optical axis adjustment device that adjusts the angle of the optical axis of the corresponding headlight by two drive motors connected in parallel to each other, corresponding to the left and right headlights. It is an object of the present invention to provide a novel optical axis adjustment device that prevents a large angular difference in the vertical direction between the optical axes of left and right headlights due to differences in characteristics or the like.

As an optical axis adjustment device that adjusts the angle of the optical axis of the headlight of a vehicle, especially an automobile, the headlight is adjusted by the output of the optical axis detection section that detects the angle of the optical axis of the headlight and the operation of a knob, etc. The output of the optical axis setting unit that sets the angle of the optical axis is compared, and if there is a difference between the two outputs, the optical axis of the headlight is set by the drive motor, which rotates in the forward or reverse direction depending on the positive or negative sign of the difference. There are some that move up and down. In such devices, the drive motor is controlled so that when there is a difference between the output of the optical axis detection section and the output of the optical axis setting section, the motor is rotated in a direction such that the difference becomes 0. Therefore, the optical axis of the headlight is at a relatively precisely set angle. One drive motor is provided for each of the left and right headlights, and the two drive motors are connected in parallel to each other and driven by one circuit.

By the way, even if drive motors are manufactured in the same way, it is impossible to make their characteristics completely the same. Therefore, even if the voltage and load applied to the drive motor are the same, and the energization time is the same, the amount of rotation will vary. are not necessarily the same. In particular, variations in starting characteristics such as starting torque are usually relatively large. Therefore, even if the two drive motors rotate for a relatively short period of time in order to minutely change the set angle of the optical axis of the headlamp, there will be a difference in the amount of rotation of the two drive motors. As a result, there is often a difference in the angle of the optical axes of the left and right headlights. If the optical axis of the headlight is repeatedly changed in response to changes in the tilt state of the vehicle body, the difference in the angle of the optical axis of the headlight due to the difference in the characteristics of the drive motor will be Even if they are minute, they become large as they accumulate. As a result, the difference in the angle of the optical axes between the left headlight and the right headlight becomes so large that it cannot be ignored, and there is a fear that this will impede safe driving.

Therefore, the present invention aims to prevent a large angular difference between the optical axes of the left and right headlights in the vertical direction from occurring. an optical axis detection section that outputs an angle of the optical axis of the headlight, an optical axis setting section that outputs an electrical signal of a magnitude corresponding to the setting amount, which can set the angle of the optical axis of the headlight by operating a knob, etc.; A comparison circuit that detects which is larger when there is a difference of more than a certain level between the electrical signal outputted by the optical axis setting section and the electrical signal outputted by the optical axis detection section, and a comparison circuit corresponding to the left and right headlights, and two drive motors for adjusting the optical axis that are connected in parallel with each other and rotate forward or reverse depending on the polarity of the voltage applied to both terminals to move the optical axis of the headlight in the vertical direction; and the two drive motors and a power source. The electrical signal output from the optical axis setting section is a circuit that is connected via a switch, for example, an ignition switch, and is controlled by the detection signal from the comparison circuit. 2 when receiving a detection signal indicating that the signal is larger than the target signal and when receiving a detection signal indicating the complete opposite.
The power supply and the drive motor are electrically connected so that the voltages applied to both terminals of the two drive motors have opposite polarities, and the electrical signal output by the optical axis setting unit and the optical axis detection unit are output. A switching circuit electrically cuts off the power source and the drive motor when there is no difference between the electrical signals and the drive motor by a certain level, and a switching circuit that temporarily changes the direction of the optical axes of the two headlights each time the switch is turned on. and initializing means for changing the value to either the upper or lower limit point.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Details of the optical axis adjustment device for a vehicle headlamp according to the present invention will be described below with reference to embodiments shown in the accompanying drawings.

FIG. 1 shows an example of an optical axis adjustment mechanism used in the optical axis adjustment device for a vehicle headlamp according to the present invention. In the figure, 1 is a headlamp, and 2 is a support member for the headlamp 1. , 3 is a stay for holding the headlamp 1, one end of which is fixed to the vehicle body 4. Reference numeral 6 denotes a shaft fixed to the other end of the stay 3, and the upper end of the support member 2 of the headlamp 1 is rotatably supported on the shaft 5.

M is a drive motor, which has a built-in speed reducer, and has a pinion 7 fixed to its output shaft 6. 8
is a rack meshed with the pinion 7, and is arranged to move in the longitudinal direction of the vehicle body 4 as the output shaft 6 of the drive motor M rotates. A transmission shaft 9 is integrally formed at the front end of the rack 8.
A ball 10 is integrally formed at the front end of the transmission shaft 9. Reference numeral 11 denotes a receiving portion fixed to the lower end of the support member 2 of the headlamp 1, and the receiving portion 11 has a spherical recess 12 that opens rearward. By fitting the ball 10 at the front end of the transmission shaft 9 into the spherical recess 12, the transmission shaft 9 and the lower end of the support member 2 of the headlamp 1 are connected like a ball joint.

13 is a variable resistor for optical axis detection, and its main body 1
The movable member 3a is fixed to the vehicle body 4 on the back surface of the rack 8 so as to face it at an appropriate distance, and the mover 13b is fixed on the back surface of the rack 8. Each terminal of this variable resistor 13 is connected to an optical axis adjustment circuit, which will be described later, via a lead wire.

When the drive motor M is rotated in the forward and reverse directions, the rack 8 that meshes with the pinion 7 fixed to the output shaft 6 of the drive motor M is moved in the front-rear direction. Then, the lower end of the support member 2 of the headlamp 1, which is connected to the transmission shaft 9 of the pinion 7 in a ball joint, is moved back and forth, and the headlamp 1 uses the shaft 5 supporting the upper end of the support member 2 as a fulcrum. The optical axis is moved vertically. Furthermore, when the rack 8 moves, the mover 13b of the variable resistor 13 moves accordingly, and the resistance value of the variable resistor 13 changes, and the resistance value increases depending on the angle of the optical axis of the headlamp 1. It becomes Satoshi.

Two such optical axis adjustment devices are provided corresponding to the left and right headlights. The variable resistor 13 for detecting the optical axis is provided, for example, only in the left optical axis adjustment mechanism.

Figure 2 shows the drive motor that tilts the left and right headlights 1.
This figure shows an example of an optical axis adjustment circuit that adjusts the angle of the optical axis of the headlamp 1 by rotating ML and MR. In the figure, VR ₁ is a variable resistor for setting the optical axis angle that moves the position of the mover S according to the rotation of a knob, etc., and VR ₂ is the variable resistor for optical axis detection shown in Figure 1. This is a variable resistor 13. Variable resistor VR ₁
has one terminal connected to the power supply E via the protective resistor R _P and the ignition switch SW,
One terminal of the variable resistor VR ₂ is connected to the anode of the power source E via the ignition switch SW, and the cathode of the power source is grounded. The other terminal of the variable resistor VR ₁ for setting the optical axis is grounded via the variable resistor VR ₃ for zero adjustment, and the other terminal of the variable resistor VR ₂ , 13 for detecting the optical axis is directly grounded. has been done. However, the ignition switch
When the SW is turned on, a voltage is generated between the movers S and D of the variable resistors VR ₁ and VR ₂ and the ground. The magnitude of this voltage changes depending on the position of the movers S and D, and as the movers S and D move closer to the terminal connected to the anode of the power source E via the ignition SW, the voltage increases, and vice versa. If you move it closer to the ground side terminal, the voltage will decrease. Therefore, the voltage between the movable element S of the variable resistor VR ₁ for setting the optical axis and the ground, that is, the optical axis setting voltage V _S has a magnitude corresponding to the amount of operation such as rotation of the knob, and is variable. The voltage between the movable element _D , 13b fixed to the rack 8 of the optical axis adjustment mechanism _shown in FIG. The size depends on the angle of. The zero adjustment variable resistor VR ₃ is used to finely adjust the optical axis setting voltage V _D to an appropriate value when the operating amount of the knob etc. is 0, and the protective resistor R _P is used for initialization described later. This is to prevent the transistors in the circuit from being destroyed by excessive current flowing through them.

COM1 and COM2 are comparators consisting of, for example, differential amplifiers, and are used to detect the optical axis setting voltage V _S and the optical axis detection voltage V _D.
It is made to compare with. Comparator COM1
receives the optical axis setting voltage V _S at the non-inverting input terminal, receives the optical axis detection voltage V _D at the inverting input terminal, and when V _S > V _D , a voltage V _COM 1 proportional to the difference V _S − V _D is generated. Occur. _R1 is a negative feedback resistor connected between the output terminal and the inverting input terminal of the comparator COM1, and this resistor _R1 makes the amplification of the comparator COM1 appropriately smaller than the amplification inherent to the comparator. Become. Comparator COM
2 receives an optical axis detection voltage V _D through a resistor R ₂ at a non-inverting input terminal, and receives an optical axis setting voltage V _S at an inverting input terminal. Its non-inverting input terminal receives the optical axis detection voltage V _D via the resistor R ₂ , so its non-inverting input voltage becomes a certain value V _D ′ smaller than V _D , and V _D ′>
When V _S ', a V _COM 2 proportional to the difference V _D '-V _S ' is generated. R ₃ is a positive feedback resistor connected between the output terminal and non-inverting input terminal of the comparator COM2, and this resistor R ₃ allows the amplification degree of the comparator COM2 to be adjusted to an appropriate level higher than the amplification degree inherent to the comparator. growing. comparator
The output voltages V _COM 1 and V _COM 2 of COM1 and 2 are connected to the transistor Q ₁ through resistors R ₄ and R ₅ respectively.
and applied to the base of Q ₂ . The emitters of transistors Q ₁ and Q ₂ are grounded, and R ₆ and R ₇ are resistors connected between the bases of transistors Q ₁ and Q ₂ and ground, respectively. RL ₁ and
RL ₂ is a relay whose one end is connected to the collectors of transistors Q ₁ and Q ₂ and the other end is grounded to _the anode of the power supply E via the ignition switch SW.
D ₂ is its protection diode. Then, the output voltages of comparators COM1 and COM2 are V _COM 1 and V _COM 2.
When exceeds a certain value, transistors Q ₁ and Q ₂ are turned on. Then, the power and ignition switch
A closed circuit consisting of the SW, relays RL ₁ and RL ₂ , and transistors Q ₁ and Q ₂ is formed, and current flows through the relays RL ₁ and RL ₂ to operate the relays RL ₁ and RL ₂ .

Therefore, if the optical axis detection voltage V _S is larger than the optical axis setting voltage V _D and the difference V _S - V _D exceeds a certain value, the output voltage of the comparator COM1
Transistor Q ₁ is turned on by V _COM 1;
Relay RL ₁ is energized. In addition, resistor R ₁ for negative feedback
The smaller the resistance value of the comparator COM1, the lower the amplification of the comparator COM1. Therefore, the two inputs of the comparator COM1 required to output the voltage V _COM1 of the magnitude required to turn on the transistor _Q1 . The voltage difference V _S −V _D increases. In addition, the optical axis setting voltage V _S is smaller than the non-inverting input voltage V _D ′ (V _D > V _D ′) of the comparator COM2, which receives the optical axis detection voltage V _D through the resistor R ₂ to the non-inverting input terminal. , and the difference
If V _D ′−V _S ′ exceeds a certain value, the comparator
Output voltage of COM2 V _COM 2 causes transformer Q ₂
turns on and relay RL ₂ is energized.
Furthermore, as the resistance value of resistor _R2 increases, the non-inverting input voltage of comparator COM2 with respect to optical axis detection voltage _VD increases.
The value of V _D ′ becomes smaller, and the difference between V _D and V _D ′ becomes larger. In this way, with resistor R ₁ provided, the comparator COM
By reducing the amplification factor of 1 and further installing a resistor _R2 , the optical axis detection voltage V _D and the non-inverting input voltage of comparator COM2 are
By creating a difference between V _D ′, the two transistors
Both Q ₁ and Q ₂ are turned off (both relays RL ₁ and RL ₂ are turned off and the drive motor is turned off).
Keep ML and MR in a non-rotating state. ) can widen the width of the optical axis detection voltage V _D region (stop region). The reason why the width of the stop area is appropriately widened in this way is to improve the stability of the operation of the optical axis adjustment device, as will be described later.

Make contacts Ma of relays RL ₁ and RL ₂ are connected to power supply E via ignition switch SW, and break contacts B are grounded. and,
A common terminal C of the relay RL ₁ is connected to one terminal X of each of two drive motors ML and MR corresponding to the left and right headlamps. Further, the common terminal C of the relay RL ₂ is connected to the other terminal Y of each of the two drive motors ML and MR. Therefore, when transistors Q ₁ and Q ₂ are off, relays RL ₁ and RL ₂
When the drive motors ML and MR are not excited,
Since both terminals X and Y of the motor are kept at ground potential, the drive motors ML and MR do not rotate. Transistor Q ₁
is turned on, and as a result relay RL ₁ is energized, one terminal X of drive motors ML and MR is connected to the anode of power supply E via common terminal S, make contact Ma and ignition switch SW. Therefore, the terminals X and Y of the drive motors ML and MR become positive, and the terminals Y of the drive motors ML and MR rotate forward, for example. Also, transistor Q ₁ remains off, transistor Q ₂ turns on and relay RL ₂
When energized, the other terminal Y of the drive motors ML and MR is connected to the anode of the power source E via the common terminal C, the make contact Ma and the ignition switch SW. Therefore, terminal Y of drive motors ML and MR
becomes positive and terminal X becomes negative, driving motors ML and MR.
For example, rotates in the opposite direction. And the drive motor ML,
For example, when MR is rotated forward (clockwise in Figure 1), the left and right headlights 1 are directed upward, and the drive motors ML and MR are rotated in reverse (counterclockwise in Figure 1). The left and right headlights 1 face downward.

Therefore, the optical axis setting voltage V _S and the optical axis detection voltage V _D
When these are approximately equal, the output voltages V _COM 1 and V _COM 2 of the comparators COM 1 and COM 2 become approximately 0, so that both transistors Q ₁ and Q ₂ remain off. Therefore, both relays RL ₁ and RL ₂ are not excited, and drive motors ML and MR do not rotate. Then, when the movable element S of the variable resistor VR ₁ for setting the optical axis is moved closer to the terminal connected to the protective resistor R _P of the variable resistor VR ₁ by operating a knob, etc., the optical axis setting voltage V _S
increases and becomes larger than the optical axis detection voltage V _D , and an output voltage V _COM 1 is generated from the comparator COM 1. When the magnitude of the output voltage V _COM 1 exceeds a certain value, the transistor Q ₁ is turned on. Then the relay
Since RL ₁ is energized, the drive motor
ML and MR rotate forward, and the headlight 1 is tilted upward. Along with this, the movable element D, 13b of the variable resistor VR ₂ , 13 for optical axis detection is connected to the ignition switch SW of the variable resistor VR ₂ , 13.
The optical axis detection voltage V _D also increases accordingly. Drive motor ML,
When rotating the MR, the optical axis detection voltage V _D is the optical axis setting voltage.
When it reaches approximately the same value as V _S , the output voltage V _COM 1 of the comparator COM 1 becomes approximately 0, so the transistor Q ₁ is turned off and the drive motors ML and MR are stopped. Move the mover S of variable resistor VR ₁ for setting the optical axis to variable resistor VR ₃ by operating the knob etc. in the opposite direction to the above case.
If the optical axis setting voltage V S is moved toward the terminal connected to the optical axis, the optical axis setting voltage V _S decreases. Then, when the optical axis setting voltage V _S becomes smaller than the non-inverting input voltage V _D of the comparator COM2 which receives the optical axis detection voltage V _D via the resistor R ₂ , the output voltage V _COM 2 from the comparator COM 2
occurs. When its output voltage V _COM 2 exceeds a certain value, transistor Q ₂ turns on and relay RL ₂
is excited. Then, as described above, the drive motors ML and MR rotate in the opposite direction, and the headlamp 1 is tilted downward. Along with this, the mover D, 13b of the variable resistor VR ₂ , 13 for optical axis detection is moved closer to the grounded terminal of the variable resistor VR ₂ , 13, and accordingly, the optical axis detection voltage V _D decreases.
The rotation of the drive motors ML and MR is determined by the optical axis detection voltage V _D
When the voltage decreases to approximately the same value as the optical axis setting voltage V _S , the output voltage V _COM 2 of the comparator COM 2 becomes approximately 0,
It stops when transistor Q ₂ turns off and relay RL ₂ becomes de-energized. Therefore, the angle of the optical axis of the headlamp 1 can be adjusted accurately by changing the position of the mover S of the variable resistor VR ₂ for setting the optical axis by operating a knob or the like. As mentioned above, by providing the resistors R ₁ and R ₂ , a stop region of an appropriate width is provided, so that when the optical axis setting angle is changed, the drive motors ML and MR are adjusted to the positive or There is no risk of the so-called hunting phenomenon, in which the optical axis adjuster rotates too much in the opposite direction, then rotates in the opposite direction to that rotation direction, and then rotates too far, and the stability of the operation of the optical axis adjustment device is improved.

INT is an initialization circuit, a time constant circuit,
A PNP type transistor _Q3 that is turned on or off depending on the output of the time constant circuit, and the transistor
Variable resistor for optical axis setting driven by Q ₃
NPN that sets the potential of mover S of VR ₁ to ground level
It consists of a type transistor _Q4 . The time constant circuit is formed by connecting resistors R ₈ , R ₉ and capacitor C ₁ in series, and the terminal on the resistor R ₈ side of the time constant circuit is connected to the anode of power supply E via ignition switch SW. and the terminal on the capacitor _C1 side is grounded. D ₃ is a discharge diode,
Connected in parallel to resistor R ₈ . The base of the transistor Q ₃ is connected to the connection point between the resistors R ₈ and R ₉ , and the emitter is connected to the connection point between the resistors R ₁₀ and R ₁₁ of the voltage divider circuit consisting of the resistors R ₁₀ and R ₁₁ . There is. And the collector of transistor Q ₃ is connected to the base of transistor Q ₄ via resistor R ₁₂ . The emitter of the transistor _Q4 is grounded, and the collector is connected to the mover S of the variable resistor _VR1 for setting the optical axis. _R13 is a transistor
This is the resistor connected between the base of _Q4 and the ground point.

The operation of this initialization circuit INT will be explained. When the ignition switch SW is turned on, the potential at the emitter of transistor _Q3 changes to the potential of resistor _R10.
The voltage rises to a value determined by the resistance ratio between _R11 and R11, and a potential difference is generated between the base and emitter, causing a base current to flow. Then, transistor Q ₃ turns on and its collector current flows into the base of transistor Q ₄ through resistor R _{12 and}
The base current of As a result, the transistor
When _Q4 is turned on, its collector and the movable element S of the optical axis setting variable resistor _VR1 connected thereto become at substantially the same potential as the ground potential. By the way, the base current of the transistor Q ₃ flows to the capacitor C ₁ via the resistor R ₉ , so the capacitor C ₁ is charged by the base current, and its terminal voltage gradually increases, and the voltage of the transistor Q ₃ increases accordingly. The base potential also increases. When the base potential reaches approximately the same level as the emitter potential of the transistor _Q3 , there is no potential difference between the base and the emitter, so the transistor _Q3 is turned off and no collector current flows. Then, the transistor _Q4 is also turned off because no current flows through its base, and its collector becomes in a state where it does not have any electrical influence on the movable element S of the variable resistor _VR1 for setting the optical axis. As a result, the potential of the mover S of the variable resistor VR ₁ rises to a height determined by the position of the mover S. In addition, the initialization circuit INT operates and transistor _Q4
When the transistor Q ₄ becomes on state
The current flowing through is limited by the protective resistor R _P. Therefore, when the initialization circuit INT operates with the movable element S of the variable resistor VR ₁ being located closer to the anti-ground terminal, it is possible to prevent excessive current from flowing through the transistor Q ₄ .
Destruction of transistor _Q4 can be prevented.

In this way, the initialization circuit keeps the movable element S of the variable resistor VR ₁ for setting the optical axis at the ground potential for a certain period of time after turning on the ignition switch SW, but the time to keep the movable element S at the ground potential is approximately It is determined by the time constant of the resistor R ₉ of the constant circuit and the capacitor C ₁ , and it changes the headlight 1 from the uppermost position to the lowermost position by the drive motors ML and MR. It is preferable to set it to the minimum necessary time.

According to the optical axis adjustment device described above, when the ignition switch is turned on, the initialization circuit is activated.
By INT, the movable element S of the variable resistor VR ₁ for optical axis setting is immediately brought to the ground potential, and the optical axis setting voltage V _S becomes approximately 0 regardless of the position of the movable element S.
Then, the optical axis detection voltage V _D is higher than the optical axis setting voltage V _S
Since it becomes larger than , the voltage from comparator COM2
V _COM 2 is output, and the output voltage V _COM 2 turns on transistor Q ₂ and energizes relay RL ₂ . Then, the drive motors ML and MR rotate in opposite directions, and the headlights are tilted downward. This tilting continues until the optical axis detection voltage V _D becomes approximately 0.
The direction of the optical axis of the headlight 1 reaches the lower limit point. After that (after a certain period of time has passed after turning on the ignition switch SW), the initialization circuit INT becomes in a state where it does not affect the potential of the mover S of the variable resistor VR ₁ for setting the optical axis, and the variable resistor VR ₁ The potential of the movable element S increases to a value determined by the position of the movable element S, and the optical axis setting voltage V _S depends on the angle of the optical axis of the headlamp 1 set by operating the knob etc. It will be the same size. Then, the headlight 1 is tilted by the drive motors ML and MR, and the angle of its optical axis directed toward the lower limit point becomes the angle set by operating the knob or the like. Such an operation is repeated every time the ignition switch SW is turned on to drive a car or the like.

Thus, each time the ignition switch SW is turned on, the optical axis of the left and right headlights 1 is automatically directed to the lower limit point, and then the angle is set as set. When the optical axis of the headlamp 1 is directed toward the lower limit point, the angular deviation in the vertical direction of the optical axis between the left and right headlights naturally disappears. Therefore, every time the ignition switch SW is turned on, the angular deviation in the vertical direction of the optical axes of the left and right headlamps 1 is corrected, and then the optical axes are adjusted as set in the optical axis setting section. The action of adjusting the angle is repeated. Therefore, due to the difference in the amount of rotation of the two drive motors ML and MR that tilt the left and right headlights 1 under the same driving conditions, a slight deviation occurred in the angles of the optical axes of the left and right headlights 1. However, the difference is corrected every time the ignition switch SW is turned on, so repeating the operation of changing the optical axis of headlight 1 will accumulate the optical axis angle deviation, which will impede safe driving. It is possible to effectively avoid the fear that a deviation of a size that would cause a problem will occur.

As described above, in the optical axis adjustment device for a headlamp of the present invention, the optical axis is directed to the angle set by the optical axis setting section by the drive motor corresponding to the left and right headlamps, respectively. The direction of the optical axis of the headlight is temporarily changed to one of the upper and lower limit points, for example, to the lower limit point, each time a switch such as an ignition switch is turned on by the initializing means. Become. Therefore, due to differences in the characteristics of the two drive motors that move the optical axes of the left and right headlights, there will be a difference in the amount of rotation of the drive motors under the same driving conditions, causing the optical axes of the left and right headlights to move up and down. Even if a slight deviation occurs in the angle in the direction, the deviation can be automatically corrected each time a switch such as an ignition switch is turned on. Therefore, each time you change the angle of the optical axis of the headlight set in the optical axis setting section, the deviation accumulates and the vertical angle of the optical axis between the left and right headlights becomes a hindrance to safe driving. It is possible to prevent such a difference in size from occurring.

In the above embodiment, when the switch is turned on, the optical axes of the left and right headlamps are directed toward the lower limit point by the initialization circuit INT, but conversely, they are directed toward the upper limit point. You can do it like this. Furthermore, although FIG. 1 schematically shows an example of the optical axis adjustment mechanism used in the optical axis adjustment device of the present invention, this mechanism is merely an example of the optical axis adjustment mechanism that can be used in the optical axis adjustment device of the present invention. This is just one example, and various types of optical axis adjustment mechanism can be considered as the optical axis adjustment mechanism that can be used in the optical axis adjustment device of the present invention, and it is not limited to the one shown in FIG. Furthermore, in the above embodiment, when the ignition switch is turned on, the initialization circuit corrects the angular deviation between the optical axes of the left and right headlamps. It is also possible to provide a separate switch so that the above-mentioned deviation is corrected when the switch is turned on, and it is not necessarily necessary to use the ignition switch as the switch for the optical axis adjustment device of the present invention. The present invention can be implemented in various ways, and is not limited to what is shown in FIGS. 1 and 2.

[Brief explanation of the drawing]

The drawings show an example of the implementation of the optical axis adjustment device for a vehicle headlamp according to the present invention, FIG. 1 is a schematic side view showing an example of the optical axis adjustment mechanism used therein, and FIG. 2 is an optical axis adjustment circuit. It is a circuit diagram showing an example. Explanation of symbols, 1...Headlight, VR...Optical axis setting section, VR...Optical axis detection section, COM...Comparison circuit,
M...Drive motor, E...Power supply, SW...Switch, RL...Switching circuit, INT...Initializing means.

Claims (1)

[Scope of Claims] 1. An optical axis detection unit that outputs an electrical signal of a magnitude corresponding to the angle of the optical axis of the headlamp, and setting the angle of the optical axis of the headlamp by operating a knob, etc. The optical axis setting section outputs an electrical signal of a magnitude corresponding to the set amount, and the electrical signal output from the optical axis setting section and the electrical signal output from the optical axis detection section exceed a certain level. A comparison circuit that detects which is larger when there is a difference, and a comparison circuit that corresponds to the left and right headlights and is connected in parallel with each other and rotates forward or backward depending on the polarity of the voltage applied to both terminals to adjust the optical axis of the headlight. two drive motors for adjusting the optical axis that move the optical axis in the vertical direction, and a circuit connected between the two drive motors and a power source via a switch, for example, an ignition switch, and controlled by a detection signal from the comparison circuit. When a detection signal is received indicating that the electrical signal output by the optical axis setting section is larger than the electrical signal output by the optical axis detection section, and a detection signal indicating the complete opposite is received. The power source and the drive motor are electrically connected so that the polarities of the voltages applied to both terminals of the two drive motors are opposite to each other when receiving the electrical signal and the light output from the optical axis setting section. A switching circuit that electrically cuts off the power source and the drive motor when there is no difference of more than a certain level between the electrical signal output by the axis detection section, and a switching circuit that electrically cuts off the power supply and the drive motor, and lights the two headlights each time the switch is turned on. An optical axis adjustment device for a vehicle headlamp, comprising initializing means for temporarily changing the direction of the axis to either an upper or lower limit point. 2. The electrical signals output by the optical axis detection section and the optical axis setting section are voltages, and the initializing means outputs either the output terminal of the optical axis detection section or the output terminal of the optical axis setting section every time the switch is turned on. 2 by changing the potential of to a predetermined value for a certain period of time.
2. The optical axis adjustment device for a vehicle headlamp according to claim 1, comprising an electronic circuit that temporarily generates a potential difference between two output terminals.