Stepped lens headlamp

p0001The invention relates to a Fresnel lens spotlight having an adjustable aperture angle of the emergent light bundle, having a reflector, a lamp and at least one Fresnel lens.

p0002The light-relevant parts in ordinary fresnel spotlights generally comprise a lamp, a Fresnel lens (Fresnel lens) and a spherical auxiliary reflector. Conventionally, there is the lamp filament is essentially immutable in the sphere center of the spherical reflector. Characterized a part of the radiated light from the lamp is reflected back into this and supports the light emission in the forward hemisphere. This front-facing light is focused by the Fresnel lens. The degree of concentration of light is dependent on the distance between the Fresnel lens and the air. the lamp filament is located at the focal point of the Fresnel lens, the result is the closest light collection. This is a quasi-parallel beam path, also called spot obtained. By shortening the distance between the Fresnel lens and the lamp of the opening angle of the emerging light beam is continuously increased. This is a divergent beam path, which is also known as Flood obtained.

p0003A disadvantage of such headlights, however, the poor light yield particularly in the spot position, since only a relatively small solid angle of the lamp is detected by the Fresnel lens. Moreover, it affects adversely that the light reflected by the spherical reflector light the lamp filament itself applies to a large extent again, it is absorbed and additionally heats up the lamp filament.

p0004From the <patcit id="pcit0001" dnum="DE3919643A1"><text>DE 39 19 643 A1</text></patcit> discloses a spotlight with a reflector, a shutter, and a Fresnel lens. With the headlight is changed by adjusting the light source the Aüsleuchtung. Thus, a change in brightness of the light is effected. Regulating the distance between the apex and reflector and between the diaphragm and the reflector is used for brightness control.

p0005From the <patcit id="pcit0002" dnum="DE3413310A1"><text>DE 34 13 310 A1</text></patcit> discloses a headlight with a lamp and a reflector or a lamp and a condenser lens. The headlamp further includes a diffusion plate or a mirror, which are both positioned at an angle of 45 °. By the mirror and the light is deflected by the lens, the light is scattered. By shifting the lens different emission of the light beam are generated.

p0006The <patcit id="pcit0003" dnum="DE10113385C1"><text>DE 101 13 385 C1</text></patcit> describes a Fresnel lens spotlight in which the fresnel lens is a converging lens whose light-source-side focal point is located in the spot position approximately in reflectorless distant focal point of the ellipsoidal reflector. Thus, the distances of the focal points of the reflector, the focal length of the reflector and the focal length of the Fresnel lens to the minimum length of such a Fresnel lens spotlight add. Furthermore, both the distance between the lamp and reflector as well as the distance between the reflector and the Fresnel lens function is set apart with a correspondingly expensive to custom guide. However, this requires additional mechanical devices.

p0007With the invention, a Fresnel lens spotlight is to be created, which has a more compact design and consequently both space than is lighter than the conventional Fresnel lens spotlight. Furthermore this Fresnels should also be easy and inexpensive to manufacture.

p0008This object is achieved in a surprisingly simple manner with a Fresnel lens spotlight according to claim 1 and a light set of claim. 13

p0009By using a Fresnel lens with a negative focal length, super compact can be achieved, which substantially corresponds to, for example, in the spot position of the Fresnel lens spotlight, only the length of the reflector together with the thickness of the Fresnel lens being used.

p0010The inventive Fresnels a significantly improved light efficiency is achieved in particular spot, but also in flood position.

p0011At the same time, the uniformity of illumination across the light field is obtained, as this example from <figref idrefs="f0004">figure 6</figref> is presented for both the spot and for a flood position.

p0012According to the invention an ellipsoidal reflector is provided with a large aperture. The spot position is set so that the lamp filament of a black body radiator, in particular a halogen lamp or the discharge arc of a discharge lamp in the reflector-side focal point of the ellipsoid is and the reflector distant second focus of the ellipsoid in about the negative or virtual reflector distant focal point of the Fresnel lens is disposed.

p0013The reflected light from the reflector light is focused prior to entering the negative lens almost entirely on the remote focal point of the ellipsoid reflector. The lamp filament located in the reflector-side focal point located or the discharge arc is displayed after passing through the Fresnel lens in the infinite and its light is thus converted into an almost parallel beam.

p0014The reflected light is no longer true, the lamp filament or the discharge arc substantially. The virtual negative focal point of the Fresnel lens coincides with the reflector distant focal point of the reflector and creates hereby an extremely compact form.

p0015With more appropriate choice of Aperturwinklels of reflector and Fresnel lens, the light reflected by the reflector is almost completely covered by the Fresnel lens and äbgestrahlt as a narrow spot beam forward.

p0016The light output is therefore considerably higher than with a conventional Fresnel lens spotlight.

p0017An embodiment of the invention is that the ellipsoid reflector consists of a metallic or transparent material. Preferably glass and polymeric materials or plastic materials are used, which may be advantageous with metal, such as aluminum, coated.

p0018Alternatively or additionally, for the manufacture either or both surfaces of the reflector provided with a system of optically thin layers ment a reflective surface. This advantageously visible radiation components are reflected and the invisible components, in particular thermal radiation components transmitted.

p0019A further preferred embodiment of the invention comprises a metallic coating on one or both main surfaces of the reflector.

p0020In another alternative configuration, the reflector may also be a metallic reflector, which may be coated both uncoated as well dielectric or metallic, to provide the desired spectral and corrosion properties.

p0021A preferred embodiment of the invention includes a Fresnel lens spotlight, wherein the light-reflecting surface of the reflector is structured to scatter light and no, one or two surfaces of the stepped lens are structured to scatter light. This results in a fixed share of the superimposition of scattered light to geometrically-optically imaged light, which avoids an image of the lamp in the light field. Preferably the reflector has for this purpose faces or facets, which make it possible to calculate its defined light-scattering portions and manufacture.

p0022With increasing miniaturization of the light source, as in the important field of digital projection or high-intensity discharge lamps, however, an increasingly pronounced medium dark area may occur, which can only be compensated with large light losses with scattering bodies inside the reflector or not yet. The conventional, used to avoid imaging of the emission center of the light source scattering facilities create only limited, if any remedy, since in this case at least the dark-central aperture cone must be homogeneously illuminated in any position of the Fresnel lens spotlight. but precisely in this way it is particularly in the spot position to large light losses, since only a dark area with very small aperture still exists but in the conventional Fresnel lens with scattering bodies the full face of the Fresnel lens for diffusing the light field is used.

p0023The inventors have found that these high light losses can be avoided in a surprisingly simple manner. It is particularly advantageous if the Fresnel lens comprises a diffuser, which is circular in a particularly preferred manner and arranged only in the center of the Fresnel lens.

p0024In this embodiment, the dark areas in the center of the illumination field can be very effectively prevented in each position of the stepped lens spotlight, but it does not come to the high losses of light in the spot position of the reflector.

p0025Surprisingly, it turns out that the geometrical-optical beam emerging from the reflector light at the location of the Fresnel lens precisely then illuminates a smaller area when the required proportion is increased to scattered light.

p0026This effect, the inventors have made to use to create the invention, an automatic or adaptive light mixing system which for the adjustment of the Fresnel lens spotlight only those stray light mixes in synchronization with the geometrically-optically imaged added light, is what needed for this position.

p0027This light mixing ratio, which can be virtually optimally adapted to the respectively required light distributions is hereinafter abbreviated only as the mixture ratio.

p0028This automatic light mixing system the correct mixing ratio and thus always a very homogeneously illuminated light field is created without this, however, unnecessary wastage occur essentially for every position of the reflector.

p0029Here, the mixing ratio of the full surface area illuminated Fresnel lens can be defined in relation to the remaining area of ​​the Fresnel lens and can be defined by the scattering properties of the negative lens of the opening angle of the scattered light by the choice of the diameter of the integrated lens.

p0030Furthermore, can vary on the integrated diffusing screen itself, the scattering effect, so that for example at the center of the lens stronger stray fields and on the edge less strongly scattering regions are arranged. This provides a more focused beam is additionally widened and it can then be implemented extremely wide illumination angle.

p0031Alternatively, the edge of the lens can be designed not only ends abruptly, but it can be designed that decreases continuously its scattering effect and extend even below or above the Fresnel lens. This further adaptations to the position-dependent mixing ratios can be made.

p0032Reference is made to the same day of the same applicant filed application entitled "Optical arrangement with fresnel lens", the disclosure of which is also incorporated by reference fully into the disclosure of the present application.

p0033According to the invention the use of the spotlight for architecture, medicine, film, stage, studio and photography as well as in a flashlight is provided.

p0034The lens may be arranged in the preferred embodiments, both the light entrance and at the light output side. Further, there is the advantageous possibility of arranging lenses at the light entrance and the light exit side. In this latter embodiment can also different stray, for example, locally different scattering, spreading discs are used.

p0035The invention will be described in more detail by means of preferred embodiments and with reference to the accompanying drawings.

Show it:

p0036<dl id="dl0001" compact="compact"><dt>Fig. 1</dt><dd>an embodiment of the Fresnel lens spotlight in the spot position, wherein the reflector distant focus of the reflector is superimposed approximately with the right-side virtual focal point of the Fresnel lens,</dd><dt>FIG. 2</dt><dd>in the <figref idrefs="f0001">Fig. 1</figref> Shown embodiment of the Fresnel lens spotlight in a first flood position, the reflector remote focal point of the reflector is arranged approximately in a close to the reflector surface of the Fresnel lens,</dd><dt>Fig. 3</dt><dd>in the <figref idrefs="f0001">Fig. 1</figref> Shown embodiment of the Fresnel lens spotlight in a second flood position with a larger opening angle, the reflector distant focus of the reflector is imaged before the reflector remote surface of the Fresnel lens by the Fresnel lens,</dd><dt>Fig. 4</dt><dd>in the <figref idrefs="f0001">Fig. 1</figref> Shown embodiment of the Fresnel lens spotlight in the second flood position with a larger opening angle, wherein by means of an auxiliary reflector, a further portion of the light is first directed into the reflector and from the latter into the Fresnel lens,</dd><dt>Fig. 5</dt><dd>a negative Fresnel lens with a centrally arranged diffusing screen,</dd><dt>Fig. 6</dt><dd>an opening angle-dependent logarithmic representation of the light intensity of the Fresnel lens spotlight in the spot and in one of its positions Flood.</dd></dl>

Detailed description of preferred embodiments

p0037In the following detailed description, it is assumed that the same reference numerals denote the same or equivalent elements in the various embodiments.

p0038Subsequently, on <figref idrefs="f0001">Fig. 1</figref> taken with respect, showing an embodiment of the Fresnel lens spotlight in the spot position. Of the stepped lens spotlight essentially contains an ellipsoidal reflector 1, a lamp 2, which may be a halogen lamp or a discharge lamp and a Fresnel lens 3 which is a lens having negative refractive power, preferably a biconcave lens stages.

p0039In <figref idrefs="f0001">Fig. 1</figref> superimposed approximately with the right-side virtual or negative focal point F 3 of the Fresnel lens 3 reflectorless distant focal point F2 of the ellipsoidal reflector. 1

p0040The light emerging from the headlamp light beam 4 is only schematically indicated in the figures by its outer marginal rays.

p0041The spot position is set so that the lamp filament or the discharge arc of the lamp 2 is disposed substantially in the reflector-side focal point F1 of the reflector. 1

p0042The reflected light from the reflector 1 is almost completely addressed in this position on the reflector remote from the focal point F2 of the ellipsoid first The right-side negative or virtual focal point F3 of the Fresnel lens 3fällt then lzusammen approximately with the focal point F2 of the reflector.

p0043It is in <figref idrefs="f0001">Fig. 1</figref> also be seen in Nahfold how the opening 5 within the reflector 1 in the parallel beam path of the light field 4 as a dark region. 6

p0044Within the Fresnel lens 3 has a circular, centrally located diffusion plate 7 is provided, which generates a defined light scattering ratio and a defined opening angle of the scattered light. This provides a defined mixing ratio of the scattered light is provided relative to the geometrically-optically imaged by the Fresnel lens 3.

p0045As an alternative to this embodiment, the lens 7 changes in a further embodiment, the scattering effect along the radius of the lens 7 in steady, so that in the middle of the lens 7 more stray fields and on the edge abruptly-ending less strongly scattering regions are arranged.

p0046In yet another alternative embodiment of the edge of the lens 7 is not just ends abruptly, but it is this formed decreases continuously its scattering effect and the latter may also be under or above the Fresnel lens extending.

p0047This system depends on further adaptations to the position-dependent mixing ratios are made so that the expert can always provide an optimum mixing ratio for a homogeneously illuminated light field or else for light fields with defined generated locally higher intensities.

p0048It is from <figref idrefs="f0001">Fig. 1</figref> can also be seen that only a small part of the total light passes through the diffusion plate 7 in the spot position.

p0049By the diffusion plate 7, there is a very homogeneous illumination, as shown in <figref idrefs="f0004">Fig. 6</figref>Showing an opening angle-dependent logarithmic representation of the light intensity of the Fresnel lens spotlight, which is given for the spot position with the line. 8

p0050<figref idrefs="f0001">FIG. 2</figref> shows in <figref idrefs="f0001">Fig. 1</figref> illustrated embodiment of the Fresnel lens spotlight in a first flood position, wherein the reflector distant focal point F2 of the reflector 1 in an approximately close to the reflector surface of the Fresnel lens 3 is arranged.

p0051Here, the value of the shift a with respect to the spot position by a mechanical guide is altered defined.

p0052The structure is basically the same in <figref idrefs="f0001">Fig. 1</figref> -described structure of the stepped lens spotlight.

p0053However, from <figref idrefs="f0001">FIG. 2</figref> can be clearly seen that increased both the opening angle of the exiting light beam 4 and the dark portion of the sixth

p0054Since in this position, however, a very high proportion of the light impinges only on a very small area in the center of the lens 7, just this range can be designed so that its forward scattering lobe approximately compensates for the dark area 6 in the far field or far field in a desired manner , It is also to<figref idrefs="f0004">Fig. 6</figref> referred, by way of example represents the light conditions with the line 9 for a flood position.

p0055Subsequently, on <figref idrefs="f0002">Fig. 3</figref> taken with respect, which in the <figref idrefs="f0001">Fig. 1</figref> illustrated embodiment of the Fresnel lens spotlight in a second flood position with an even larger opening angle than in <figref idrefs="f0001">FIG. 2</figref> shows, the reflector distant focal point F2 of the reflector 1 before the reflector remote surface of the Fresnel lens 7 is imaged by the Fresnel lens. 7

p0056Here, a larger area of ​​the diffusion plate 7 than in <figref idrefs="f0001">FIG. 2</figref> shown by lights and can its entire scattering behavior to be adapted to the circumstances of this flood position.

p0057A further preferred embodiment shows <figref idrefs="f0002">Fig. 4</figref>, In this embodiment, substantially corresponds to an additional auxiliary reflector 18 to the embodiments described above, by the auxiliary reflector 18 light of the lamp 2, which in itself<figref idrefs="f0002">Fig. 4</figref> would spread to the right and no longer reach the reflector 1 would by reflection into the reflector. 1 This allows both the light which is exemplified by the optical path 19 and do not contribute without the auxiliary reflector for lighting would be used but it can also be the otherwise directly enters the Fresnel lens 3 of the light can be better used for the desired light distribution.

p0058The shape of the auxiliary reflector 18 is advantageously chosen so that this reflected light does not return to the light source of the lamp 2, for example a filament or a discharge zone, and this additionally heated unnecessarily.

p0059Alternatively it can be applied 18 to the inner and or outer side of the glass body of the lamp 2 the auxiliary reflector. For this purpose the glass of the lamp body may be shaped accordingly to achieve the desired directivity for the reflected light.

p0060<figref idrefs="f0003">Fig. 5</figref> exemplifies a Fresnel lens 3 with diffusing glass 7, as this is used by the invention. The Fresnel lens 3 has a transparent base body 10 and a fresnel lens ring system 11 with annular lens portions 11, 12, 13 within which the circular diffusion plate 7 is arranged.

p0061The diffusion plate 7 is defined structured or has facets 15, 16, 17 in wide ranges defined exactly scattering behavior, which in the <patcit id="pcit0004" dnum="DE10343630"><text>German patent application DE 103 43 630</text></patcit> of the same applicant are described, entitled "Lens".

p0062However, the invention is not limited to the embodiments described above of lenses.

p0063Particularly advantageous place of the Fresnel lens spotlight described above is used in a lighting set together with a respect to the prior art significantly reduced electrical power supply or ballast. This power supply can be designed both electrically and mechanically less when compared to the prior art the same usable light output of inventive Fresnels be there has a much higher luminous efficacy. Less weight is therefore required and claimed during transport and storage less storage space.

p0064In this way, but the overall thermal load on illuminated objects and people is also, in particular when using dichroic reflectors reduced.

p0065Furthermore, the Fresnel lens spotlight according to the invention can advantageously be used to increase the luminous efficiency also in flashlights, in which the available electrical energy is in principle more limited.

LIST OF REFERENCE NUMBERS

p0066<dl id="dl0002" compact="compact"><dt>1</dt><dd>reflector</dd><dt>2</dt><dd>lamp</dd><dt>3</dt><dd>fresnel lens</dd><dt>4</dt><dd>outgoing light beam</dd><dt>5</dt><dd>Opening in the reflector 1</dd><dt>6</dt><dd>dark area</dd><dt>7</dt><dd>Lens</dd><dt>8th</dt><dd>Intensity distribution in the spot position</dd><dt>9</dt><dd>Intensity distribution in flood position</dd><dt>10</dt><dd>basic body</dd><dt>11</dt><dd>Fresnel lens ring system</dd><dt>12</dt><dd>annular lens sections</dd><dt>13</dt><dd>dto.</dd><dt>14</dt><dd>dto.</dd><dt>15</dt><dd>facet</dd><dt>16</dt><dd>dto.</dd><dt>17</dt><dd>dto.</dd><dt>18</dt><dd>auxiliary reflector</dd><dt>19</dt><dd>by auxiliary reflector reflected beam path</dd></dl>