Headlight for a bicycle

Abstract

The disclosure relates to a headlight for a bicycle. The headlight is designed as a projection headlight with a semiconductor light source, the emitted light of which is projected directly via a lens. The lens has an outer surface acting as a light exit surface, which is divided by a step into an upper region and a lower region. The lens has an inner surface acting as a light entry surface, which, opposite the upper region, has a curved zone for homogenizing blue light components.

Description

Field of the invention

[0001] The invention relates to a headlight for a bicycle, which is designed as a projection headlight. Background of the invention

[0002] Bicycle headlights commonly used in practice are usually designed as reflector headlights. The light emitted by the light source is reflected by a reflector toward the light exit lens. This has the disadvantage that the corresponding headlights are relatively long due to the reflector.

[0003] In contrast, published patent application WO 2021 / 212370 A1 shows a projection headlight. In a projection headlight, the light emitted by the light source, in particular an LED, is projected onto the road using a converging lens. This allows the headlight to be more compact and simpler. A lens divided into at least two zones makes it possible to project a sufficiently wide light field, which is overlaid by a spot of more focused light. The light is projected onto the lens via a light guide in front of the LED.

[0004] To generate white light, the semiconductor light source used includes a conversion layer. The semiconductor emits blue light, which is partially converted into yellow light in the conversion layer. White light is thus generated by mixing at least two different wavelengths. The refractive index of the lens used is wavelength-dependent. This can result in visibly blue areas of the emitted light field, particularly in the area of the focused spot.

[0005] Document FR 3 145 594 A1 shows a vehicle headlight with a stepped lens. Object of the invention

[0006] The invention, in contrast, is based on the object of at least reducing such blue components of the light field. According to a further aspect of the invention, the headlight should be designed to be simpler and / or more compact. Summary of the invention

[0007] The object of the invention is already achieved by a headlight according to claim 1 and by a bicycle equipped with the headlight.

[0008] Preferred embodiments and further developments of the invention can be found in the subject matter of the dependent claims, the description and the drawings.

[0009] According to a first aspect, the invention relates to a headlight for a bicycle. A bicycle within the meaning of the invention also includes one with an electric auxiliary drive, i.e., an e-bike or pedelec, as well as a multi-track pedal-driven vehicle. The headlight is operated, in particular, with a low voltage of 5 to 50 V. The headlight according to the invention can be designed both as a wired headlight, for example, for use on an e-bike with a power connection, and as a battery-powered light.

[0010] The headlight is designed as a projection headlight and contains a semiconductor light source. The light emitted by the semiconductor is projected directly onto the road via a lens without first being reflected by a reflector.

[0011] The semiconductor light source is preferably aligned coaxially with a central axis of the lens. The semiconductor light source can be designed, in particular, as an LED, in particular as an LED cluster. The semiconductor light source is preferably designed as an SMD LED, which is arranged on a circuit board inserted into the headlight.

[0012] The lens comprises an outer surface acting as a light exit surface, which is divided by a step into an upper region for forming a focused region of the emitted light field and a lower region for forming a wider region of the emitted light field.

[0013] The lower part of the lens has a larger outer diameter than the upper part. This allows for a wide light field with a bright center.

[0014] The lens can be made of a plastic, in particular a PMMA.

[0015] The refractive index of the n d of the lens is preferably between 1.4 and 1.6, in particular between 1.45 and 1.55.

[0016] The Abbe number v d can be between 55 and 65. The transmission of the lens is preferably over 90%, especially 90 to 95%.

[0017] According to the invention, the lens comprises an inner surface acting as a light entry surface, which has a curved zone opposite the upper region for homogenizing blue light components.

[0018] The light entry surface is thus curved in some areas in the upper section. The light entry surface is preferably otherwise flat.

[0019] It has been found that in this efficient way, blue and yellow light components are mixed in such a way that visible blue areas of the light field can be largely avoided.

[0020] According to one embodiment, the curved zone is formed as a circular segment in a plan view of the back of the lens, the circular segment curving from a base to an edge.

[0021] The curved zone may have a maximum depth t of 0.05 to 1 mm, preferably 0.1 to 0.3 mm, at an apex, in particular at an upper end of the circular segment.

[0022] In one embodiment, the curved zone comprises a base that is vertically spaced from the step by 30 to 60%, preferably 40 to 55%, of the height of the upper region. The curved zone thus occupies only a portion of the surface of the upper region of the lens. The base is, in particular, formed as a chord of the circular segment.

[0023] The light exit surface can have a diameter of 25 to 50 mm, preferably 30 to 40 mm. The light exit surface and / or the light entry surface are preferably circular in plan view.

[0024] In a further development of the invention, a concave indentation is provided in a lower part of the lower area in a side view. Light components in the lower area of the lens are projected further forward via the concave indentation. This avoids unnecessarily high brightness directly in front of the headlight. At the same time, portions of the emitted light in the lower area are used to create the focused light field further forward in the desired area.

[0025] Preferably, the curved zone is curved only in the longitudinal direction. The curvature of the curved zone increases steadily upwards, particularly from the base. "Top" and "bottom" as well as "front" and "rear" refer to the intended mounting position of the headlight.

[0026] The curved zone starts in particular from the base and rises to a maximum angle at the apex relative to the flat inner surface of 1 to 5°.

[0027] According to one embodiment of the invention, the curved zone is formed as a depression in the back of the lens.

[0028] The depression can extend in particular to the edge of the light entry surface.

[0029] The lens may have a collar around the light entry or exit surface, which serves to mount the lens in the headlight.

[0030] Preferably, the semiconductor light source is spaced 10 to 20 mm from the opposite light entry surface.

[0031] Due to the projection principle, the headlight can be quite short, typically 30 to 50 mm long. The length is defined as the length from the rear of the housing to the frontmost point of the lens.

[0032] According to another aspect, the disclosure relates to a headlight for a bicycle.

[0033] In particular, this may have at least one of the features described above.

[0034] The headlight is designed as a projection headlight with a semiconductor light source, the emitted light of which is projected directly via a lens, wherein the lens has an outer side acting as a light exit surface, which is divided by a step into an upper region for forming a focused region of the emitted light field and a lower region for forming a wider region of the emitted light field.

[0035] According to the disclosure, the lens has an inner surface acting as a light entry surface, wherein light from the semiconductor light source strikes the light entry surface directly without a further optical component being arranged between the semiconductor light source and the light entry surface.

[0036] This allows the headlight to be simpler and more compact.

[0037] The light entry surface is preferably flat, except for the optional curved zone. This ensures a particularly compact design.

[0038] The semiconductor light source is preferably designed as an LED array.

[0039] In a further development, the headlight comprises at least one upper LED and at least one lower LED, wherein the at least one lower LED can be separately activated for a high beam function. The light from the lower LED hits the upper area of the lens at a more acute angle and is emitted at a higher angle than the light from the upper LED.

[0040] The invention further relates to a bicycle, in particular designed as an e-bike, which comprises the headlights described above. Brief description of the drawings

[0041] The subject matter of the invention will be explained below with reference to an embodiment based on the figures Fig. 1 to Fig. 13 will be explained in more detail. Fig. 1 is a perspective view of a headlight according to the invention. Fig. 2 is a sectional view. Fig. Figure 2a is a top view of the headlight circuit board. Fig. 2b shows an alternative embodiment. Fig. 3 and Fig. 4 are perspective views of the lens. Fig. 5 is a side view of the lens. Fig. 6 is a central longitudinal section of the lens. Fig. 7 is a detailed view of area A according to Fig. 6. Fig. 8 is a top view of the back of the lens. Fig. 9 is a simulation of the ray path of the upper part of the lens from the side. Fig. 10 shows, in contrast, the beam path when using a lens which does not include the curved zone according to the invention. Fig. 11a shows the beam path of the upper area from above and Fig. 11b shows the beam path of the lower part of the lens. Fig. 12 shows the beam path of the lower part of the lens from the side. Fig. Figure 13 is an illustration of the emitted light field of the headlight in high beam mode. Detailed description of the drawings

[0042] Fig. 1 shows a perspective view of an embodiment of a headlight 10 according to the invention for a bicycle.

[0043] The headlight 10 comprises a housing 11, which can be circularly cylindrical.

[0044] Cooling fins 13 are provided on the back of the housing 11.

[0045] At the front, the headlight includes a lens 100 as a light exit surface. The lens 100 is designed as a projection lens and is convex in shape, at least in sections.

[0046] The headlight 10 can be attached to a bicycle via the holder 14.

[0047] A reflector 15 is attached to the side of the housing at the bottom.

[0048] Fig. 2 is a central longitudinal section of the Fig. 1 headlight 10.

[0049] Inserted into the headlight 10 is a circuit board 17, which comprises a chip 16 with LEDs 18. In this embodiment, the LEDs 18 are part of an SMD LED array.

[0050] The LED array is arranged coaxially with the lens 100. The planar emitters of the LEDs 18 are arranged perpendicular to the central axis of the lens 100.

[0051] There are no optical components arranged in the beam path between the LEDs and the lens 100; the light from the LEDs hits the rear light entry surface of the lens 100 directly.

[0052] The housing 11 comprises a base 12 which thermally contacts the circuit board 17 so that heat can be dissipated, in particular via the rear part of the housing with the cooling fins.

[0053] The lens 100 comprises a collar 101. A screw-on ring 20 engages around the collar 101 and thus secures the lens 100 in the installed state in the housing 11.

[0054] A seal 19 may be provided between the housing 11 and the collar 101.

[0055] Fig. 2a is a top view of the circuit board 17 with the LED array.

[0056] The chip 16 comprises a plurality of LEDs 18. In particular, the LEDs 18 can be arranged in at least two rows and at least two columns. In this embodiment, the array has two rows and three columns.

[0057] The upper line is used to create a light field when the headlight is not switched to high beam mode, with the light field comprising a broad portion that is emitted via the lower area of the lens.

[0058] The lower row of the array, on the other hand, is only switched on for a high beam function of the headlight.

[0059] The upper line is above the central axis of the lens and the lower line is below the central axis of the lens.

[0060] If the light rays from the lower row hit the upper part of the lens at a sharper angle, these rays are emitted further upwards or at a larger angle to the central axis.

[0061] This produces a brighter, straight-ahead light focus.

[0062] Fig. Figure 2b shows the circuit board 17 for an alternative embodiment of the invention in which the headlight is not equipped with a switchable high beam function.

[0063] In contrast to the embodiment according to Fig. 2a is just a single row of LEDs on the chip. These are preferably located above the center axis of the lens.

[0064] Fig. 3 is a perspective view of the lens 100 from the front.

[0065] The collar 101 comprises at least one form-locking element 102, which in cooperation with a corresponding form-locking element of the housing (e.g. indentation) forms a rotation lock relative to the housing.

[0066] The lens 100 is divided into an upper region 110 and a lower region 120 by a step 103.

[0067] The width of step 103 increases continuously from the center to the edge 111. The lower region 120 thus has a larger radius than the upper region 110. Thus, the lower region 120 serves to form a broader portion of the light field than the upper region 110.

[0068] In this embodiment, the step 103 runs approximately centrally relative to the height of the lens 100. According to other, not shown, embodiments of the invention, the step 103 may also be arranged off-center, or the lens 100 may have more than two regions separated from each other by several steps.

[0069] The edge 111 of the optically active region of the lens 100 is circular. Due to the curvature of the lens in the upper region 100, the edge 111 extends into the collar 101 at the top.

[0070] Fig. 4 is a perspective view of the lens 100 from the back.

[0071] The back of the lens 100 is designed as a flat light entry surface 104.

[0072] A curved zone 130 is provided in the upper area.

[0073] In this embodiment, the curved zone 130 is formed in plan view as a circular segment with the chord 131 and the upper vertex 132.

[0074] The circular segment is adjacent to the collar 101 of the lens 100, which in the mounted state is covered by the housing, in particular the ring of the housing.

[0075] The side view shows that a concave recess 122 is present at the lower end of the lower region 120. The concave recess 122 serves to shape the beam and projects the lower portions of the light emitted by the LED further forward.

[0076] The edge 121 of the lower region 120 is curved in side view.

[0077] The lower edge 121 runs from the step 103 first inwards and then outwards again.

[0078] The edge 111 of the upper region 110 extends upwards from the end of the step 103.

[0079] The lower end of the edge 111 of the upper region 110 ending at the step is spaced from the upper end of the edge 121 of the lower region 120.

[0080] The lens 100 comprises a base 105 arranged on the collar 101 with a circular cylindrical contour, wherein the edge 111 of the upper region extends from the circular cylindrical contour in the front plane of the collar 101.

[0081] The edge 121 of the lower region 120 extends downwards from the point 106 on the step 103, wherein in the side view the point 106 is spaced one third to two thirds of the length of the step 103 in the side view from its beginning or end.

[0082] Fig. 6 is a central longitudinal section of the lens 100.

[0083] In the central longitudinal section, the area with the curved zone 130 can be seen.

[0084] Fig. 7 is a detailed view of area A of the Fig. 6.

[0085] The curved zone 130 is curved only in the longitudinal direction from the chord 131 to the apex 132 inwards towards the light exit surface.

[0086] The curvature increases continuously and reaches a maximum depth t of 0.1 to 0.3 mm at the apex 132.

[0087] Fig. Figure 8 is a plan view of the underside of the lens 100, with hidden edges shown in dashed lines.

[0088] In the upper region 110, the chord 131, from which the curved zone 130 begins, is spaced vertically from the step 103 by 40 to 55% of the height of the upper region, relative to the height of the upper region 100.

[0089] The curved region 130 is formed as a depression which starts from the tendon 131 and ends at the inside edge of the collar 101.

[0090] Fig. Figure 9 is a simulation of the beam path in the upper region of the lens according to the invention, where Fig. 10 is a simulation of the beam path of an identical lens, which, however, is not provided with the zone according to the invention. The simulation shows that according to Fig. 10 the light rays pass through the upper part of the lens essentially parallel to each other.

[0091] However, due to the curved zone according to Fig. 9, the light rays are less parallel and intersect. This ensures better mixing of blue and yellow light components. Visibly blue-colored areas can thus be avoided in the light field.

[0092] Fig. 11a shows, from above, the beam path from the upper part of the lens and Fig. 11b shows the beam path from the lower part of the lens.

[0093] The beam path from the lower part of the lens is more spread out than the upper part.

[0094] Fig. Figure 12 shows the beam path from the lower area from the side. It can be seen that this beam path is different from the beam path from the upper area according to Fig. 9 is projected onto the road over a greater length.

[0095] Fig. 13 is a simulation of the light field of the headlight according to the invention in high beam mode.

[0096] It can be seen that the light field includes a bright spot in the upper area, which is cut off almost straight at an angle between 0 and 6°. This portion is directed straight ahead.

[0097] In front of it there is a slightly darker scattering area, which extends to the upper edge.

[0098] The light field always has a width over an angular range of + / -20 to 25° in an angular range along the direction of travel from 0 to -25°.

[0099] To each side, the headlight emits a light field with an angle of up to 25° + / - 5° and vertically over an angle of 45° + / - 5° (relative to the central axis of the lens).

[0100] The invention made it possible to provide an improved projection headlight in which visible blue components of the field of vision are almost completely avoided. List of reference symbols 10 headlights 11 housings 12 bases 13 cooling fins 14 holders 15 Reflector 16 chips 17 Circuit board 18 LED 19 Seal 20 rings 100 lenses 101 Collar 102 Form-locking element 103 Level 104 flat light entry surface 105 bases 106 points 110 upper area 111 edge 120 lower area 121 Rand 122 concave indentation 130 curved zone 131 tendon 132 vertex

Claims

[1] Headlight (10) for a bicycle, wherein the headlight (10) is designed as a projection headlight with a semiconductor light source, the emitted light of which is projected directly via a lens (100), wherein the lens (100) has an outer side acting as a light exit surface, which is divided by a step into an upper region (110) and a lower region (120), characterized by that the lens (100) has an inner surface acting as a light entry surface, which has a curved zone (130) opposite the upper region (110) for homogenizing blue light components. [2] Headlight (10) according to the preceding claim, characterized by that the curved zone (130) is formed in a plan view as a circular segment, wherein the circular segment curves from a base to an edge. [3] Headlight (10) according to one of the preceding claims, characterized bythat the curved zone (130) has a maximum depth t of 0.05 to 1 mm, preferably 0.1 to 0.3 mm, at an apex (132). [4] Headlight (10) according to one of the preceding claims, characterized by that the curved zone (130) has a base, in particular designed as a chord, which is spaced vertically from the step by 30 to 60%, preferably 40 to 55%, of the height of the upper region. [5] Headlight (10) according to one of the preceding claims, characterized by that the light exit surface has a diameter of 25 to 50 mm, preferably 30 to 40 mm. [6] Headlight (10) according to one of the preceding claims, characterized by that in a lower part of the lower region (120) in a side view there is a concave indentation (122). [7] Headlight (10) according to one of the preceding claims, characterized by that the curved zone (130) is only curved in the longitudinal direction. [8] Headlight (10) according to one of the preceding claims, characterized by that the curvature of the curved zone (130) increases continuously from the base upwards. [9] Headlight (10) according to one of the preceding claims, characterized by that the flat inner side of the lens (100) adjoins the base of the curved zone (130). [10] Headlight (10) according to one of the preceding claims, characterized by that the curved zone (130) rises from the base to a maximum angle at the apex (132) relative to the flat inner surface of 1° to 5°, and / or that the semiconductor light source is spaced 10 to 20 mm from the light entry surface, and / or that the headlight (10) has a length of 30 to 50 mm. [11] Headlight (10) for a bicycle according to one of the preceding claims, characterized bythat light from the semiconductor light source hits the light entry surface directly without any further optical component being arranged between the semiconductor light source and the light entry surface. [12] Headlight (10) according to one of the preceding claims, characterized by that the semiconductor light source is designed as an LED array. [13] Headlight (10) according to one of the preceding claims, characterized by that the headlight comprises at least one upper LED and at least one lower LED, wherein the at least one lower LED can be switched on separately for a high beam function. [14] Bicycle comprising a headlight (10) according to any one of the preceding claims.

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