DEVICE FOR HEAD LAMP ADJUSTMENT

Abstract: A device for adjusting headlamps, especially headlamps on vehicles and particularly car headlamps. According to the invention, a lens (6) is positioned in connection to the forward portion of the vehicle (4) and capable to focus light (3), which is emitted from lamps (2) of an opposing vehicle (1), to one of a number of photosensitive elements (7-11) arranged substantially vertically above each other, which lens (6) and elements (7-11) are rigidly connected relative to each other. Each of the elements (7-11) is capable to send a signal to a control circuit when light is focused on the element (7-11) in question. A drive means is provided and capable to move the position of the reflector of the headlamp and thereby the angle of the optic angle of the headlamp relative to the vehicle (4). The control circuit is capable to control the drive means to move the optic axis of the headlamp to a predetermined angle to the longitudinal axis (41) of the vehicle (4), depending on that of the elements (7-11) which sends a signal to the control circuit.

Description: Device for headlamp adjustment This invention relates to a device for adjusting headlamps especially headlamps on vehicles and particularly car headlamps. A known device of the kind here concerned is disclosed in SE-PS No. 7611514-6. It comprises a number of movable part where the so-called moire technique is used, which implies that the device is relatively complicated. The device acc¬ ording to said patent 761151-4-6, however, is designed so as to render it possible to adjust an object relative to a certain plane without utilizing a reference other than the vertical line. The present invention has the object to provide a device, which is substantially simpler and which is especially adapted to the adjusting of car headlamps, though it can be used also for other purposes. Car drivers as well as authorities since long have desired automatic or semiautomatic headlamp adjustment, a.o. becaus a headlamp with correct setting when the car is not loaded very often assumes an incorrect position relative to a road way and opposing traffic when the car is loaded. Car head¬ lamps also have a tendency to gradually assume an incorrect setting, a.o. owing to variations in the spring system of the car and to alterations in the adjusting devices of the headlamps. Modern car headlamps are designed so that one bulb per head lamp includes a light source for dipped light and a light source for headlight. Adjustment of the headlamps is effect by turning the reflector of the headlamps relative to the car body.The bulb is positioned stationary relative to the reflector. ' ■- - - - The adjustment desired to be achieved is that the optic axis of the reflector meets a plane horizontal roadway at a certain angle. The reflector and the bulb are formed so th dipped light will not occur to an appreciable extent above a certain level over the roadway, and that the light emitted at headlight has good intensity close to the roadway at a substantial distance from the headlamp. The main problem at automatic adjustment of headlamps on a car can be referred to the fact, that the angle of inclin- ation of the car to the roadway, i.e. the inclination of the longitudinal axis of the car to the roadway, varies with the load of the car, due to luggage, passengers etc . . A further problem is that control means used for the adjust¬ ing operation must not be designed so, that they give rise to additive errors, which easily can be the case when the control means are based on an adjustment made in the factory or workshop, and the control means measure the deviation from this adjustment when the load of the car is changed for the first time, and all adjustments thereafter are based on the latest adjustment of the headlamps. The present invention solves the aforesaid problems and offers a very simple device for adjusting a.o. car head¬ lamps. The invention is based o * n the understanding of using a reference in the form of headlamps of opposing cars and thereby to render it possible to adjust the headlamps on the basis of actual conditions. The present invention, thus, relates to a device for adjust¬ ing headlamps, especially headlamps on vehicles and part- icularly car headlamps, comprising a lens positioned in connection to the forward portion of the vehicle and capable to focus light emitted from lamps of P.pposingvehicles to one of a plurality of photosensitive elements arranged syi__ai__r _3--- J antially vertically above each other, which lens and elements are rigidly connected relative to each other, and each of the elements is capable to emit a signal to a control circuit when light is focused on the element in question. The device according to the invention is characterized in that it comprises a drive means to move the position of the reflector of the headlamp, and thereby the angle of the optic axis of the headla p relat¬ ive to the vehicle, and that the control circuit is. capable to control the drive means to move the optic axis of the headlamp to an angle to the longitudinal axis of the vehicle, which angle is predetermined depending on which of the elements emits a signal to the control circuit. The invention is described in greater detail in the follow- ing, with reference to embodiments shown by way of example. These embodiments refer to car headlamps, but also head¬ lamps of another type and on other vehicles can be designed according to the invention. The headlamps on an aircraft, for example, can be made self-adjusting by causing a refer- ence headlamp to emit light toward the aircraft when it is loaded and ready for lift-off. Also other types of head¬ lamps, such as stationary headlamps with a certain setting, can be equipped with a device according to the invention. In the accompanying drawings Figs. 1 and 2 show schematically a device according to the invention seen from the side and in two different positions relative to the light emitted by an opposing car, Fig.' 3 shows schematically an adjusting device, pig. 4 shows a headlamp seen from the front, with the invention applied thereon, Fig. 5 shows the device according to Figs. 1 and 2 on an enlarged size, which is close to natural size, Fig. 6 shows a modified portion of the device seen from the front, and Fig. 7 shows a modified portion of the device and a schematic layout of a control means for controll- ing a motor. In Fig. 1 an opposing car 1 is shown, the headlamps 2 of which emit light 3 toward a car 4, of which only a wheel is shown, and which is equipped with a device according to the invention designated generally by 5. For the sake of clarity, the device 5 is shown in Figs. 1 ' and 2 with incorrect relative size. The device 5 comprises a lens 6 with a focal distance B of, for example, 100 mm, see Fig. 5- Photosensitive elements, preferably a set of photodiodes 7-11 or phototransistors or corresponding photosensitive elements, are mounted rigidly relative to the lens. The photodiodes 7-11 are mounted perpendicularly to the optic axis 12 of the lens 6 and at a distance corres¬ ponding to the focal distance B of the lens 6. The lens preferably is a plastic or glass lens with a diameter D of about one third of the focal distance, for example a dia¬ meter of 30 mm. The photodiodes 7-11 are mounted tightly adjacent each other, as shown in Fig. 5- The object of this is that light incident to the diodes shall meet a photodiode and, thus, cannot meet an interstice between two p-hotόdiodes. The device 5. comprising the lens 6 and photodiodes 7-11, according to a first embodiment is mounted rigidly relative to the car body 18. According to a preferred embodiment, the lens 6 is positioned to the side of the reflector 14 and behind the glass of the headlamp 13, as indicated in Fig. 4, which shows a headlamp 13 from the front where both the reflector 14 and the lens 6 are indicated by dashed lines. By this arrangement, the device is well protected "' and the light path to the lens 6 can be kept clean by util¬ izing a normally existing car headlamp wiper (not shown). The reflector 14 and glass 15 of the headlamp normally are assembled in modern cars, and the bulb 16 associated with the headlamp 13 is mounted rigidly relative to the reflector 14. A modern car headlamp 13 is adjusted in that the suspension means of the reflector 14 is moved or turned relative to the car body. According to the invention, the reflector 14 of the head¬ lamp ' 13 is suspended hingedly via a stay member 17 relative to the body,and via a drive means provided on the opposite side of the reflector 14 it can be moved relative to the body in the longitudinal direction of the car. Said drive means comprises an additional stay member 22, through which a threaded axle 19 extends in a hole threaded in the stay member 22. The axle 19 is rotatably connected to an electric motor 20. Upon rotating the axle in one direction or the other, thus, the stay member 22 is moved in the longitudinal direction of the car body 18, whereby the headlamp 13 is turned about the suspension point 21 of the firstmentioned stay member 17. Hereby, thus, the light emitted by the head-- lamp 13 is directed at different angles relative to a road¬ way. Hereinafter the main light radiation direction of the headlamp or reflector is called the optic axis 40 of the headlamp. The longitudinal axis of a car, further, which is horizontal when the car is unloaded and stands on a horizontal surface, is called the longitudinal axis 4l of the car. The size of the photodiodes 7-11 in relation to the focal distance B of the lens determines for which angular change- of the optic axis 12 of the lens 6, i.e. the longitudinal It was found that the light emitted by a car headlamp is sufficiently well directed in relation to a roadway, when the angle of the optic axis of the headlamp to a horizontal plane is located within about 1 degree. For this reason, the photodiodes 7-11 can be dimensioned with a diameter of about 1 mm when the focal distance B is 100 mm. When the distance between two adjacent photodiodes is 1,25 mm, at the focal distance of 100 mm a dissolution of about 0,7 degrees is obtained. The device 5 operates as follows. Assuming that the longitudinal axis of the car is in parallel with the roadway, and the roadway is plane in longitudinal direction, the light 3 from an opposing car 1 is refracted through the lens 6 to one of the photodiodes. The lens 6 and the photodiodes 7-11 are so positioned in relation to the car body that the photodiode designated by 10 is met by the incident:, light.- When the angle of the longitudinal axis of the car to the roadway is changed to form the angle p^ to the roadway, due for example to load in a rear luggage compartment, the optic axis 12 of the lens 6, thus, as shown in Fig. 2, will form the same angle 0{ to the roadway and the angle (180 - C ) to the light 3 incident from an opposing car. Hereby the lens 6 will refract the light to another one of the photo- diodes, in Fig. 2 the photodiode 8, viz. the one which is located on the extension of a line 3 from the headlamp 2 of t car 1 through the centre 23 of the lens 6. At different angles (X between the longitudinal axis of the car and the roadway, thus, incident light 3 will meet diff- erent photodiodes. At the embodiment three photodiodes 7,8,9 are stated for indicating when the longitudinal axis of the car is angular forward-upward relative to the roadway, and one photodiode 11 for indicating when the longitudinal axis of the car is angular forward-downward relative The indication obtained when the light 3 meets one of the photodiodes 7-11, thus, informs on the angle, which the longitudinal axis of the car forms with the roadway, and thereby informs on the angle, which the optic axis of the headlamps shall form with the longitudinal axis of the car for adjusting the headlamp correctly. The said electric motor 20 is of known type and preferably designed so that it automatically stops in one of a number of predetermined stop positions when voltage is applied to one of a plurality of contact points of the motor. The motor 20 is provided with at least as many stop positions as there are photodiodes 7-11. The motor 20 can be designed to rotate through a number of revolutions or parts of a revolution between two such adjacent stop positions. The aforesaid axle 19 is provided with threads of such a pitch, that the stay member 22 is moved through a certain predeterm¬ ined distance relative to the axle 19 between each of two adjacent stop positions of the motor 20. Each of these pre¬ determined positions of the stay member 22 relative to the axle 19, which positionsat the embodiment shown in the Figures are five in number, corresponds to a certain angle of the optic axis of the headlamp with the longitudinal axis of the car. The difference between two such adjacent angles, further, is equal to the change of the angle of the longitudinal axis of the car relative to the roadway, which change is required for the incident light to shift from meeting one photodiode to meeting an adjacent photodiode. According to a preferred embodiment,each, of the photodiodes 7-11 is capable to emit a signal to a control circuit 23 for the motor 20. The control circuit 23 is capable to send an impulse to the motor to assume a stop position.specific for each photodiode. Hereby, thus, the optic axis of the headlamp will assume a predetermined angle to the longitud- inal axis of the car, in response to hat of the The position of the optic axis of the headlamp 13 relative to the longitudinal axis of the car is basically adjusted in the factory and possibly in connection with service of the car. 5 The basic adjustment, for example, is carried out when the longitudinal axis of the car is horizontal and in parallel with a horizontal support. Light incident horizontally to and on the same level as the lens 6 is focused to the photodiode 10. The motor 20, therefore, is adjusted to the 0 stop position corresponding to a signal from the photodiode 10. The optic axis of the headlamp thereafter is adjusted, for example, by adjusting the position of the motor 20 to a correct one. Assuming that the car remains unloaded or is loaded in such 5 a way, that its longitudinal axis 41 remains in parallel with the roadway 43, incident light 3, thus, will meet the photodiode 10. When the car is loaded, for example to the position shown in Fig. 2, the light 3 will meet the photodiode 8, which hereby 0 sends a signal to the control circuit 23, which in its turn causes the motor 20 to stop in the stop position correspond¬ ing to the photodiode " 8. In this case the motor axle 19 moves the stay member 22 in the direction to the motor 20. Hereby, thus, the angle of the optic axis 40 of the headlamp 5 to the roadway is changed by an angle corresponding to the change of the angle of the longitudinal axis 4l of the car, i.e. the angle -X in Fig. 2, whereby the headlamp again is adjusted correctly. When the load of the car is changed another time, for example ° so that the longitudinal axis 41 of the car covers an angle to the roadway between the positions shown in Figs. 1 and 2, the photodiode 9 will be met by incident light 3. This implie that the motor 20 is controlled to assume a stop position corresponding to the photodiode 9, i.e. proceeding from the motor being in the stop position corresponding to the photodiode 8, as shown in Fig. 2, the motor will move the stay member 22 in the direction away from the motor. When 5 the stop position has been assumed, the optic axis 40 of th headlamp again forms a correc angle with the roadway. The headlamps are adjusted in a corresponding manner every time, a photodiode actuates the control means 23. -. In Fig. 3 a simple form of a control circuit 23 is shown, ° where a motor 20 is used which is capable to assume a cert¬ ain stop position when it is energized via a certain conduct In Fig. 7 five such conductors 24-28 are provided, each of which is connected via a thyristor 29-33 to a voltage source. Each thyristor 29-33 is connected to a photodiode 7- 5 The photodiodes-7-11 are connected to the voltage source. Each of the thyristors 29-33 is- capable to conduct current from the voltage source to the respective conductor 24-28: ' when the respective phototransistor sends a signal of a certain strength to the thyristor. When the current passes 0 through the respective conductor 24-28, the motor assumes • the respective stop position, as described above. In the foregoing only one headlamp has been mentioned. Preferably, however, a motor 20 is mounted on each of the headlamps to be adjusted, but only one indication device 5 is required. Several headlamps, of course, may eclt.edmechanically, in which case only one motor 20 is required. The control means 23, of course, can be varied widely, and also- the constructional design of the motor 20, without abandoning the idea of the invention. The control means 23, for example,can.-be÷amicrocomputer, and the motor can be one controlled by a microcomputer. According to a preferred embodiment, an adjustment of the headlamps is actuated by the car driver by means of a switc 34, but the adjustment can also take place automatically. The advantage of an actuation effected by the driver is, that the driver can select a plane portion of a road and actuate adjustment when an opposing car approaches. The switch 34 can preferably be designed so that it switches off automatically when an adjustment has been carried out. In the foregoing a first embodiment has been described, at which the lens 6 and photodiodes 7-11 are mounted rigidly relative to a car body 18. According to a second embodiment the lens 6 and photodiodes 7-11, instead, are mounted rigid in relation to the reflector 14 of the headlamp 13. Accord- ** ing to this embodiment, thus, the lens and photodiodes follow along with the reflector when its position is adjust by means of the motor 20. The object of this second embodiment is that the light 3 of an opposing car always shall be incident to ' a specific photodiode, when the headlamp is adjusted correctly, for example to the photodiode 10, see Fig. 1. When the car is loaded down to the position shown in Fig. 2 the photodiode 8 will be met by light.3. A control circuit corresponding to the one described above is capable to send a signal to the motor 20 in such a way. that the head- lamp 13 is adjusted to correct position, which is character ized in that the light 3 of an opposing car again meets the photodiode 10, because also the lens 6 and photodiodes 7-11 are turned together with the headlamp. According to this embodiment, the control circuit preferabl is designed so that each of the photodiodes, by sending a signal to the control circuit, indicates by this signal, how much the headlamp must be turned about the turning poin 17, so that the light 3 of an opposing car shall meet the -_. __. photodiode 10, i.e. that the headlamp is adjusted correctly According to the invention, thus, the photodiodes 7-11 and the lens 6 can be mounted rigidly in relation to the car bo or in relation to the reflector of the headlamp. The contro circuit, of course, can be designed according to a suitable choice and order so as to be capable to send necessary signals to the motor for adjusting the headlamp to correct position. The light 3 of an opposing car has been mentioned above without commenting thereon more precisely. On modern passenger cars and also on certain buses..- and lor the headlamps are positioned substantially at the same ' heig Assuming that the intended adjustment is carried out when the distance to an opposing car is 20 to 100 meters, prefer 30 to 50 meters, the adjustment of the headlamps will not be appreciably affected by the headlamp position of the opposing car. The adjustment will take place in any case wit an acceptable angle interval, because the change of angle taking place at the movement of the light between two adjace photodiodes is regarded to correspond to an acceptable chang of angle from the ideal setting of the headlamps. Of course, more than five photodiodes can be used, whereby the precision of the adjustment can be increased. In Fig. 6 an embodiment is shown where greater photodiodes are used. In order to obtain a vertical distance between the centre of the photodiodes 35~39 which is smaller than the diameter of the photodiodes, the diodes can be arranged in a zigzag * pattern, as shown in Fig. 6, where the photodiod 35-39 are seen straight from the front, i.e. from the right in Fig. 5. It is preferred, however, that the photodiodes are arranged substantially abutting one another is a In order to effect the adjustment to take place at the distances stated, the photodiodes 7-11 and thyristors 29-33 chosen so, that the photodiodes open the thyristors at a- light intensity, which corresponds to that obtained from a modern passenger car at the distance in question. When the adjustment well has commenced, the adjustment is not affected by light incident to the photodiodes during the adjusting phase. The row of photodiodes further are designed so that light incident, for example, from a lorry with lamps positioned at a great height, falls below the photodiode 11 of lowermost position. As stated above, the lens 6 preferably is located to the sid of the reflector 14 and behind the glass of the headlamp 13. According to a preferred embodiment, the glass 15 of the headlamp in the place of the lens is provided with a number of grooves, flutes or the like, which are located to the side of each other and so designed, that incident light is refracted in the grooves to a horizontal line, which meets one of the photodiodes 7-11. By this design, light from cars can be used for said adjustment, which cars are not in a position straight ahead of a car equipped with the present device, but are in a position obliquely ahead, as in a curve. in order to prevent the effect of scattered light, street lamps etc., a filter can be provided in connection to the lens 6 for filtering off light of certain wavelangth ranges, " so that the light incident to the photodiodes consists to the greatest part of a wavelength interval , which is emitted by halogen lamps. In said control circuit, furthermore, one or more electronic filters can. be built in, which are capable to filter off signals originating from light supplied with a voltage of a • -- certain frequency, for example 50 or 60 c.p.s. Hereby a great amount of light is filtered off which is driven by voltage from the public mains. The detail design of the device, in respect of the lens, photosensitive elements and control circuit, of course, can be varied without abandoning the invention idea. As ment¬ ioned, the entire control circuit may be controlled by a microcomputer or the like. Another modified embodiment is shown in the right-hand portion of Fig. 7. Instead of positioning photosensitive elements 7-11 at the distance B from the lens 6, at this embodiment the ends of a plurality of fibre-optic light conductors are positioned where•in Fig. 5 the photodiodes 7-11 are -located. Each of the light conductors 44-48 is capable to conduct the light to a. photodiode or phototransis 7-11, see Fig. 7. The ends of the light conductors are fixed in position ih a plate 49. The advantage of this embodiment is. that photodiodes. or -transistors of a greater size can be used, and that all electronic equipment can be arranged at the instrument panel of the car, i.e. inside the car. The invention, of course, must not be regarded restricted to the embodiments set forth above, but can be varied withi the scope of the attached claims.

Claims: Claims 1. A device for adjusting headlamps, especially headlamps on vehicles and particularly car headlamps, comprising a lens (6), which is located in connection to the forward portion of the vehicle (4) and capable to focus light (3) emitted from lamps (2) of the opposing vehicle (1) to one of a-number of photosensitive elements (7-11) arranged subst ially vertically above each other, which lens (6) and elements (7-11) are rigidly connected relative to each other, and each of the elements (7-11) is capable to send a signal to a control circuit (23) when light is focused on the element (7-11) in question, c h a r a c t e r i s e d i n that drive means (19,20,22) are provided to move- the position of the reflector (14) of the headlamp. (13) and thereby the angle of-.the optic axis (40.) of the ' headlamp (13 relative to the vehicle (4), and that the control circuit (23) is capable to control the drive means (19,20,22) to move the optic axis (40) of the headlamp (13) to a pre¬ determined angle to the longitudinal axis (4l) of the vehicle (4), depending on which of the elements (7-11) sends a signal to the control circuit (23). 2. A device as defined in claim 1, c h a r a c t e r ¬ i z e d i n that the lens (6) and photodiodes (7-11) are rigidly connected to the body (18) of the vehicle (4). 3. A device as defined in claim 1, c h a r a c t e r ¬ i z e d i n that the lens (6) and photodiodes (7-11) " are rigidly connected to the reflector (14) of the headlamp (13) and, thus, follow along with the reflector of the headlamp when the position of the reflector relative to the body (lδ) of the vehicle (4) is changed. 4. A device as " defined in claim 1,2 or 3 . c h a r a c t ¬ e r i z e d i n that said predetermined angle correspon a correct adjustment of the optic axis of the headlamp (13) relative to a plane support, on which the vehicle is locate 5. A device as defined in claim 1,2,3 or 4, c h a r a c t e r i z e d i n that the photosensitive elements (7-11) are photodiodes or phototransistors, which (7-11) are locat substantially abutting each other in a substantially vertic row, which is located at a distance from the lens (6) corr ponding to the focal distance (B) of the lens (6). 6. A device as defined in claim 1,2,3,4,or 5, c h a r - a c t e r i z e d - i n that a switch (34) is provided and capable to actuate the control circuit (23), which switch (34) is intended to be controlled by the driver of -._ the vehicle (4) . 7. A device as defined in claim 1,2,3 * 4,5 or 6, c h a r - a c t e r i z e d i n that the lens (6) is located prot¬ ected behind the glass (15) of a headlamp (13). • 8. A device as defined in claim 7, c h a r a c t e r i z e i n that the glass (15) of the headlamp (13) at the place of the lens (6) is provided with a number of vertical grooves, flutes and the like located to the side of each other. 9. A device as defined in any one of the preceding claims, c h a r a c t e r i z e d i n that the drive means (19 * 20,22) comprises an electric motor (20) capable to be driven to one of a number of predetermined stop positions, the number of which corresponds at least to the number of elements (7-11) * and that the control circuit (23) is capabl to control the motor (20) so as to assume a stop position, which corresponds to the one of the elements (7-11) which sends said signal to the control circuit (23).

Inventors: BERGKVIST LARS ANDERS, BERGKVIST, LARS, ANDERS
Applicants: PRESSMASTER TOOL AB
Application year: 1982
Main classification: B60Q1
IPC codes: B60Q1