Illumination – Supported by vehicle structure – Condition responsive
Reexamination Certificate
1999-08-11
2001-02-06
O'Shea, Sandra (Department: 2875)
Illumination
Supported by vehicle structure
Condition responsive
C362S466000, C362S460000, C362S459000, C315S082000, C315S360000
Reexamination Certificate
active
06183118
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an automatic leveling apparatus which automatically tilts the light axis of a headlamp in such a direction so as to offset a pitch angle that corresponds to an inclination of a vehicle in the longitudinal direction thereof. This operation will be hereinafter referred to as an “automatic leveling operation”. In particular, the present invention is related to an automatic leveling apparatus for automatically controlling the alignment of the light axis of the headlamp in a vertical direction on the basis of a pitch angle obtained while the vehicle is stationary.
2. Description of the Related Art
A headlamp of this type is built so that, for example, a reflector equipped with a light source is supported on a lamp body so as to be tiltable about a horizontal axis, and the light axis of the reflector (headlamp) is tiltable about the horizontal axis by means of an actuator.
A conventional automatic leveling apparatus comprises pitch angle detection means and a vehicle speed sensor, both of which are mounted on a vehicle, and a control section for controlling operation of an actuator on the basis of detection signals output from the detection means and the sensor. The light axis of a headlamp (reflector) is controlled so as to constantly remain in a predetermined position relative to the road surface.
Automatic leveling comprises dynamic automatic leveling for constantly effecting an automatic leveling operation either while the vehicle is travelling or stationary, and static automatic leveling for effecting an automatic leveling operation while the vehicle is stationary.
The conventional automatic leveling apparatus is arranged so as to perform a leveling operation in real time in response to a change in the orientation of a vehicle stemming from acceleration and deceleration during travel and a change in the weight of the vehicle stemming from loading and unloading of cargo on or from the vehicle during halts, regardless of whether or not the vehicle is traveling or stationary. For this reason, the actuator is operated a very large number of times, thus consuming a large amount of power. Further, components constituting a drive mechanism, such as a motor and gears, are required to have great durability, thus adding to the overall cost of the apparatus.
SUMMARY OF THE PRESENT INVENTION
The present invention has been conceived in view of the foregoing drawbacks in the related art, and the object of the present invention is to provide an inexpensive automobile headlamp automatic leveling apparatus which can diminish the frequency of operation of the actuator and can be used for a long period of time.
To achieve the object, the present invention provides an automobile headlamp automatic leveling apparatus which includes a headlamp whose light axis is tilted upward and downward in relation to a vehicle body by means of an actuator; a control unit for controlling the operation of the actuator; vehicle speed detection means for detection of the speed of the vehicle; and pitch angle detection means for detecting a pitch angle of the vehicle. The control unit controls the operation of the actuator on the basis of a detected pitch angle such that the light axis of the headlamp maintains a constant, predetermined angle in relation to the road surface. The control unit effects single control of operation of the actuator at the time of illumination of the headlamp while the vehicle is stationary, and while the vehicle is stationary, the operation of the actuator is controlled at given time intervals counted by an interval timer.
While the vehicle is stationary, the control of operation of the actuator is commenced at predetermined time intervals under the condition that the headlamp is illuminated. Accordingly, the number of times the actuator is operated is smaller than conventional apparatuses, resulting in reduced power conservation. Further, the constituent members of a drive mechanism undergo less abrasion.
According to a second aspect of the present invention, the automobile headlamp automatic leveling apparatus as defined in the first aspect is further characterized in that first control of operation of the actuator is performed simultaneously with illumination of the headlamp.
The illuminating action of the headlamp serves as a leveling switch, thus affording great convenience to the driver.
According to a third aspect of the present invention, the automobile headlamp automatic leveling apparatus is further characterized in that the interval between operations of the actuator is set so as to become longer than the maximum time required by the actuator to perform a single leveling operation.
If the interval between a previous control operation and a subsequent control operation is shorter than the maximum time required by the actuator to activate the actuator, the actuator shifts to the next operating state before reaching a target value. After the actuator has reached the target value without fail according to the previous control, the actuator is activated according to the next control. Thus, the frequency of activation of the actuator is reduced, thereby increasing the longevity of the actuator compared to the related art.
Further, since the interval between the operations of the actuator is increased, a change arising in pitch angle during an interval between a previous control operation and the next control operation can be omitted without involvement of operation of the actuator. More specifically, all the operations performed between the intervals are consolidated into the operation of the actuator in the next control operation. Accordingly, the frequency of activation of the actuator is reduced.
According to a fourth aspect of the present invention, the automobile headlamp automatic leveling apparatus is further characterized in that, if the actuator is brought into an uncontrolled state after the control of operation of the actuator has been started, the actuator continues to operate by only the amount of operation instructed by the control unit immediately before the actuator is brought into an uncontrolled state.
Even if the actuator is brought into an uncontrolled state as a result of extinction of the headlamp or traveling of the vehicle, the actuator is not stopped before completion of operation of the actuator. The actuator is activated to a predetermined position corresponding to the pitch angle without being interrupted. Accordingly, the light axis of the headlamp is prevented from being changed to an unintended position.
According to a fifth aspect of the present invention, the automobile headlamp automatic leveling apparatus is further characterized in that, on the basis of the pitch angle detected by the pitch angle detection means, the control unit is arranged so as to calculate the amount of control operation required to activate the actuator, even during the interval period of operation of the actuator and regardless of whether or not the headlamp is illuminated.
Even in an unilluminated state or an interval period, in either of which the operation of the actuator is not controlled, the pitch angle detected by the pitch angle detection means is taken into the control unit at all times, where the pitch angle is processed as the amount of control operation. All the pitch angles taken into the control unit are utilized as control data, thus enabling utilization of many pitch angles as control data. Accordingly, a proper leveling operation associated with correct detection of a vehicle's orientation (pitch angle) becomes feasible.
According to a sixth aspect of the present invention, the automobile headlamp automatic leveling apparatus is further characterized in that the control unit comprises a storage section for storing a pitch angle detected by the pitch angle detection means regardless of whether or not the headlamp is illuminated, and immediately after the headlamp has been illuminated, the control unit controls the operation of the actuator on the basis of the pitch angl
Takeuchi Hideaki
Toda Atsushi
Koito Manufacturing Co. Ltd.
O'Shea Sandra
Sughrue Mion Zinn Macpeak & Seas, PLLC
Ward John Anthony
LandOfFree
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