Headlights for vehicles and adjustment procedures

Abstract

The invention relates to a headlight for vehicles with a light source unit (1) comprising a number of light sources (2), an optical unit (3) by means of which light (17, 17') emitted by the light source unit (1) is focused into a predetermined light distribution, a holding device for the light source unit (1) and for the optical unit (3), wherein the holding device for the light source unit (1) comprises an actuating element (4, 4', 4") with which at least one light source (2) of the light source unit (1) is coupled, wherein the extension of the actuating element (4, 4', 4") in the direction of an optical axis (10) of the optical unit (3) is adjustable depending on the temperature of the actuating element (4, 4', 4"), that the actuating element (4, 4', 4") is electrically connected to an electrical control unit (16) and that the control unit (16) generates such a control signal.that in the switching-on state of the light source unit (1) the actuating element (4, 4', 4") is supplied with such an electric current that the extension of the actuating element (4, 4', 4") in the direction of the optical axis (10) changes such that the at least one light source (2) is located at a predetermined distance (b) to the optical unit (3) in which the light source (2) is focused.

Description

[0001] The invention relates to a headlight for vehicles with a light source unit containing a number of light sources, an optical unit by means of which light emitted by the light source unit is imaged to a predetermined light distribution, a holding device for the light source unit and for the optical unit.

[0002] Furthermore, the invention relates to an adjustment method for the headlight.

[0003] DE 10 2020 114 767 A1 discloses a headlight for vehicles comprising a light source unit and an optical unit for generating a predetermined light distribution. The light source unit and the optical unit are fixedly arranged in a housing of the headlight via a holding device. The light source unit comprises a plurality of light sources arranged on a common circuit board. The optical unit consists of a plurality of lenses arranged spaced apart from one another along an optical axis, wherein one lens is arranged so as to be adjustable in the direction of the optical axis. This lens is displaced or adjusted relative to the other lenses in such a way that a predetermined light image of the headlight is generated. This can be accompanied by the light source unit being focused on the optical unit.A disadvantage of the known headlight is that an actuator is required to adjust at least one lens. This makes the basic adjustment relatively complex.

[0004] The object of the present invention is to provide a headlight for vehicles and an adjustment method which ensures a basic adjustment or focusing of a light source unit to an optical unit at low manufacturing costs and in a simple manner.

[0005] To achieve this object, the invention in conjunction with the preamble of patent claim 1 is characterized in that the holding device for the light source unit comprises an actuating body to which at least one light source of the light source unit is coupled, wherein an extension of the actuating body in the direction of an optical axis of the optical unit is designed to be adjustable depending on a temperature of the actuating body, that the actuating body is electrically connected to an electrical control unit and that the control unit generates a control signal such that, in the switched-on state of the light source unit, the actuating body is supplied with an electrical current such that the extension of the actuating body in the direction of the optical axis changes such that the at least one light source is located at a predetermined distance from the optical unit in which the light source is focused.

[0006] According to the invention, the light source unit or a number of the light sources of the light source unit are fastened in a housing of the headlight via an adjusting body, which can be supplied with electrical current by means of an electrical control unit. The applied electrical current changes the temperature of the adjusting body, and thus, according to its coefficient of expansion, its length expands as the temperature increases. The thermal expansion of the adjusting body affects the distance between the light source unit and the optical unit, so that by adjusting the current flowing through the adjusting body, the light source unit can be focused on the optical unit. Advantageously, this allows for a simple compensation of the joining tolerances occurring in the light source unit during a basic adjustment (focusing) of the headlight.

[0007] According to a preferred embodiment of the invention, the heat-expandable adjusting body is arranged between a light source of the light source unit and a circuit board of the light source unit. The thermal expansion of the adjusting body thus directly affects the distance between the light source and the circuit board. Since the circuit board of the light source unit is arranged substantially perpendicular to an optical axis of the optical unit, this ensures a change in the distance between the light source and the optical unit in the direction of the optical axis of the latter. Alternatively, the adjusting body could also be arranged between the circuit board and the housing of the headlight; however, this increases the installation space requirement.

[0008] According to a further development of the invention, the actuator has electrical connections through which the electrical current (direct current) is fed into the actuator. Preferably, the electrical connections of the actuator are connected to contact points on the circuit board via electrical lines, so that the component count is relatively low. The control unit, preferably arranged on the circuit board, for controlling the light source unit can also be used to control the actuator.

[0009] According to a further development of the invention, the predetermined value of the distance between the light source or light source unit and the optical unit is determined by an optical analysis method during manufacture of the headlight. For example, the distance value can be determined using a wavefront analysis. If the at least one light source of the light source unit is arranged at the predetermined distance from the optical unit, the control signal for controlling the actuator is "frozen." The control signal for the actuator is thus fixed. The control signal for the actuator and the control signal for the light sources are activated or deactivated synchronously. This ensures that, when the headlight is switched on, the at least one light source is always arranged at the focusing distance from the optical unit.

[0010] According to a further development of the invention, the control signal is fixed and thus constant when the headlight is switched on. If the ambient temperature of the headlight is in an extreme range, for example, in extreme heat or cold, the control signal for the actuator can be varied depending on the ambient temperature, so that the desired basic focusing setting is maintained.

[0011] According to a further development of the invention, a plurality of light sources of the light source unit are firmly connected to the circuit board via a common actuator. Thermal expansion of the actuator thus uniformly and simultaneously changes the distance of all light sources from the optical unit.

[0012] According to a further development of the invention, the light sources of the light source unit are each firmly connected to the circuit board via a separate adjusting element, with the adjusting elements being arranged at a distance from one another. In this way, the distance between individual light sources can be adjusted independently of the other light sources. Advantageously, this allows for a simple adjustment of a different color fringe. The color of the headlight can also be set to blue or yellow, for example.

[0013] According to a further development of the invention, the actuator body consists of a plastic material, a composite material, or a fiber-reinforced material. The actuator body is designed as a solid body, which can be isotropic or anisotropic.

[0014] To achieve the object, the invention comprises the inventive method according to patent claim 13.

[0015] The particular advantage of the method according to the invention is that no components need to be movably mounted to perform the basic adjustment or focusing of the light source unit relative to the optical unit. All that is required is a thermally expandable actuator, which is subjected to an electric current. This results in relatively low costs. Adjustment accuracy is also relatively high, since the distance can be easily adjusted, preferably by utilizing a linear thermal expansion curve.

[0016] Embodiments of the invention are explained in more detail below with reference to the drawings.

[0017] They show: Fig. 1 a side view of a headlight according to a first embodiment and Fig. 2 a side view of the headlight according to a second embodiment.

[0018] A headlight according to the invention has a housing (not shown) in which a light source unit 1 containing a plurality of light sources 2 and an optical unit 3 containing a lens are fixedly arranged.

[0019] A holding device for holding the light source unit 1 comprises an actuator 4, via which the light sources 2 are firmly connected to a circuit board 5. The circuit board 5 is attached to or coupled to the housing of the headlight via fastening means (not shown).

[0020] The light sources 2 are each designed as LED light sources or LED chips, which according to a first embodiment according to Fig. 1 are arranged on a common substrate 6. The substrate 6 is connected to a front side 7 of the thus integrally formed solid actuator body 4', arranged on a side facing the lens 3. A rear side 8 of the actuator body 4', facing away from the optical unit 3, is firmly connected to the circuit board 5.

[0021] The actuating body 4, 4' can, for example, be connected in a materially bonded manner, in particular by gluing, to the substrate 6 of the light sources 2 and the circuit board 5.

[0022] It is assumed that a plurality of light sources 2, for example 16,000 light sources 2, are arranged on the actuator 4' in the form of a matrix for generating an adaptive light.

[0023] A holding device for holding the optical unit 3 has holding webs 9 by means of which the optical unit 3 is fastened to the circuit board 5.

[0024] The light sources 2 are arranged at a distance a from the circuit board 5. The distance a of the light sources 2 from the circuit board 5 essentially corresponds to an extension or length of the actuator body 4, 4' running in the direction of an optical axis 10.

[0025] The actuator body 4, 4' is solid and cuboid-shaped. It can be made of a plastic material, a composite material, or a fiber-reinforced material.

[0026] The actuator 4' has a first electrical connection 11 and a second electrical connection 12 arranged at a distance from the first electrical connection, from which, in the present exemplary embodiment, electrical lines 13 are connected to a first contact point 14 and a second contact point 15 of different conductor tracks (not shown). The conductor tracks lead to a control unit 16, which is also arranged on the circuit board 5. In this way, the actuator 4' can be supplied with an electrical current, by means of which it is heated and can be adjusted or moved according to a thermal expansion curve in the direction of the optical axis 10 or in or against a main radiation direction H of the headlight.

[0027] The adjusting body 4' consists of such a material that there is a proportionality between the current application or temperature change and a change in extension (length change) of the adjusting body 4' in the direction of the optical axis 10.

[0028] The electrical control unit 16 generates such a control signal that, when the light sources 2 are switched on, the actuating body 4 is changed in its length in the direction of the optical axis 10 such that the light sources 2 are arranged in a focused manner to the optical unit 3 or the lens, as shown in Fig. 1. The electrical current required to flow through the actuator 4' to heat it is determined once within the framework of an optical analysis process, for example by means of a wavefront analysis.

[0029] If, for example, the axial distance between the light sources 2 and a center line M of the lens 3 is too large, the electric current applied to the actuator 4' is increased by means of the control unit 16 until the light sources 2 have a predetermined distance b from the center line M of the lens 3. The electric current required in this desired position of the light sources 2 is stored in a memory of the control unit 16. In the focused desired position of the light source unit 1 according to Fig. 1, in which the light sources 2 of the light source unit 1 are arranged at the distance b to the center line M of the lens 3, the light sources 2 are arranged focused to the lens 3. In Fig. 1 shows limit rays 17, 17' which pass through the center of the lens 3 or focal point F of the lens 3 and produce a predetermined light image 18.

[0030] Preferably, the control unit 16 also serves to control the light sources 2. For simplicity of illustration, the electrical connections of the light sources 2 to conductor tracks of the circuit board and thus to the connection to the control unit 16 are not shown.

[0031] The control signal for the light sources 2 generated by the control unit 16 and the control signal for the actuator 4' are activated or deactivated synchronously. When the light sources 2 are switched on, the actuator 4' is supplied with the corresponding electrical current. When the light sources 2 are switched off, no electrical current flows through the actuator 4', so that the light sources 2 are at a distance b+Δx from the center line M.

[0032] When the light sources 2 are switched on, the actuator 4' is supplied with a constant current.

[0033] According to a second embodiment of the invention according to Fig. 2, a headlight is provided which differs from the headlight according to Fig. 1 in that the light sources 2 are not coupled or connected to the circuit board 5 via a common actuating body 4', but rather via individual actuating bodies 4". The actuating bodies 4" assigned to the light sources 2 are arranged at a distance from one another. This ensures that, if the actuating body 4" is made of an isotropic material, no stresses arise when the actuating bodies 4" change in their extension in the direction of the optical axis 10.

[0034] Advantageously, the distances of the light sources 2 to the center line M of the lens 3 can be set differently. For example, a first light source 2' can be set at a greater distance to the center line M of the lens 3 than a second light source 2". For example, a color fringe gradient can be set or limited in this way. For simplified representation, Fig. 2 only the electrical lines (wires 9) of the outer actuator 4" are shown. It is understood that all other actuators 4" also have corresponding electrical connections.

[0035] According to the invention, the light source unit 1 is adjusted to the optical unit 3 by applying electrical current to the actuator 4, 4', 4" to such an extent (electrical current value of such a magnitude) that the light sources 2 are at a predetermined distance b from the lens 3. At normal ambient temperatures, once the control signal (electrical current) applied to the actuator 4, 4', 4" has been set, this causes the actuator 4, 4', 4" to always assume the same extension in the direction of the optical axis 10, so that the light sources 2 are focused on the optical unit 3. Once the control signal has been determined, synchronous control of the actuator 4, 4', 4" together with the light source unit 1 can ensure that the light source unit (1) is adjusted to the optical unit (3) when the headlight is switched on.

[0036] Under extreme environmental conditions, for example, very high or low ambient temperatures, a change in the control signal can be preset when corresponding predefined temperature thresholds are exceeded or undershot, so that the light sources 2 are arranged or adjusted in the desired position b relative to the lens 3 even under extreme ambient temperatures. The change in length of the actuator 4 due to the extreme ambient temperature is thus compensated.

[0037] According to an alternative embodiment of the invention (not shown), the actuating body 4 can also be arranged on a side of the circuit board 5 facing away from the optical unit 3. The light sources 2 are arranged on a side of the circuit board 5 facing the optical unit 3. In this embodiment, the optical unit 3 is not attached to the circuit board 5, but rather to another carrier that is not firmly connected to the circuit board 5. In this embodiment, the actuating body 4 is firmly connected to the housing via a carrier (not shown). In contrast to the embodiment according to Fig. 1, the circuit board 5 together with the light sources 2 rests on the actuator 4 and not just the light sources or the light sources together with the substrate 6 on the actuator 4.

[0038] Preferably, the 4" adjusting bodies are made of the same material.

[0039] The focus is always adjusted by heating the adjusting body 4, 4', 4". If it is determined by analysis that the (target) distance value b is smaller than the current distance value, the holder for the lens 3 must be adjusted so that the distance between the light source 2 and the lens 3 increases, i.e. is greater than the distance value b. Subsequently, the adjustment to the target distance value b can be carried out by fine adjustment according to the invention. List of reference symbols 1 light source unit 2.2',2" light sources 3 Optical unit / lens 4.4',4" actuator 5 circuit board 6 Substrat 7 Front 8 Back 9 piers 10 optical axis 11 1. Electrical connections 12 2. Electrical connections 13 electrical cables 14 1. Contact points 15 2. Contact points 16 Control unit 17.17' rays 18 Photograph b,Δx distance H Main radiation direction M center line F focal point

Claims

[1] Headlights for vehicles with - a light source unit (1) containing a number of light sources (2), - an optical unit (3), by means of which light (17, 17') emitted by the light source unit (1) is imaged to a predetermined light distribution, - a holding device for the light source unit (1) and for the optical unit (3), characterized by , - that the holding device for the light source unit (1) comprises an adjusting body (4, 4', 4") to which at least one light source (2) of the light source unit (1) is coupled, wherein an extension of the adjusting body (4, 4', 4") in the direction of an optical axis (10) of the optical unit (3) is adjustable depending on a temperature of the adjusting body (4, 4', 4"), - that the actuator (4, 4', 4") is electrically connected to an electrical control unit (16) and - that the control unit (16) generates such a control signal that, in the switched-on state of the light source unit (1), the actuating body (4, 4', 4") is supplied with such an electrical current that the extension of the actuating body (4, 4', 4") in the direction of the optical axis (10) changes such that the at least one light source (2) is located at a predetermined distance (b) from the optical unit (3) at which the light source (2) is focused. [2] Headlight according to claim 1, characterized by that the actuating body (4, 4', 4") is arranged between the light source (2) and a printed circuit board (5), wherein a front side (7) of the actuating body (4, 4', 4") facing the optical unit (3) is firmly connected to a substrate (6) of the light source (2) and a rear side (8) of the actuating body (4, 4', 4") facing away from the optical unit (3) is firmly connected to the printed circuit board (5). [3] Headlight according to claim 1 or 2, characterized bythat the actuator (4, 4', 4") has electrical connections (11, 12) via which the electrical current is fed into the actuator (4, 4', 4"). [4] Headlight according to one of claims 1 to 3, characterized by that the predetermined distance (b) of the light sources (2) to the optical unit (3) is determined by an optical analysis method. [5] Headlight according to one of claims 1 to 4, characterized by that the electric current flowing through the actuator (4, 4', 4") in the switched-on operating state of the headlight is constant. [6] Headlight according to one of claims 1 to 5, characterized by that the light sources (2) of the light source unit (1) are firmly connected to the circuit board (5) via a common actuating body (4, 4'). [7] Headlight according to one of claims 1 to 5, characterized bythat the light sources (2) of the light source unit (1) are each firmly connected to the circuit board (5) via a separate adjusting body (4, 4"), wherein the adjusting bodies (4, 4") are arranged at a distance from one another. [8] Headlight according to claim 7, characterized by that adjusting bodies (4") firmly connected to predetermined light sources (2) are subjected to an electrical current which is different from that of adjusting bodies (4") firmly connected to other light sources (2) in such a way that a colour fringe effect is avoided. [9] Headlight according to one of claims 1 to 8, characterized by that the adjusting body (4, 4', 4") is cuboid-shaped and / or solid. [10] Headlight according to one of claims 1 to 9, characterized by that the adjusting body (4, 4', 4") consists of a plastic material or a composite material or a fiber-reinforced material. [11] Headlight according to one of claims 1 to 10, characterized bythat the light sources (2) are arranged on a substrate (6) which is integrally connected to the actuating body (4, 4', 4"). [12] Headlight according to one of claims 1 to 11, characterized by that the electrical connection of the actuating body (4, 4', 4") comprises two electrical lines (13) via which the electrical connections (11, 12) of the actuating body (4, 4', 4") are connected to different contact points (14, 15) of the printed circuit board (5), and that the contact points (14, 15) lead via conductor tracks to the control unit (16), from which a direct electrical current flows into the actuating body (4, 4', 4"). [13] Method for adjusting a distance (b) of a light source unit (1) relative to an optical unit (3), characterized byin that an adjusting body (4, 4', 4") which is variable as a function of temperature in a direction of extension of an optical axis (10) of the optical unit (3) and by means of which the light source unit (1) is held is heated in the operating state of the light source unit (1) in such a way that the light source unit (1) has a predetermined distance (b) from the optical unit (3). [14] Method according to claim 13, characterized by that the adjusting body (4, 4', 4") is heated by means of electric current. [15] Method according to claim 13 or 14, characterized by that the electric current flowing through the adjusting body (4, 4', 4") is adjusted such that the light source unit (1) is focused on the optical unit (3).

Images