DE102004014045A1 - Fresnel lens headlamp with coupled change in the distance of lighting elements - Google Patents

Abstract

To provide a Fresnel spotlight having an adjustable aperture angle of the emergent light beam with a preferably ellipsoidal reflector, a lamp and at least one Fresnel lens having a more compact design and thus being both more space efficient and lighter than the conventional Fresnel spotlights, a negative focus and virtual lens will be provided Focus used as a Fresnel lens.

Description

The The invention relates to a Fresnel spotlight, with adjustable opening angle the emerging light beam, with a reflector, a lamp and at least one Fresnel lens.

The photometrically relevant parts in ordinary Fresnel spotlights usually include a lamp, a Fresnel lens (Fresnel lens) and a spherical one Auxiliary reflector. conventional the lamp filament is essentially invariable in the sphere center of the spherical reflector. As a result, part of the light emitted by the lamp is in this reflects back and the light emission in the front half space supported. This Forward directed light is focused by the Fresnel lens. Of the Degree of light bundling however, is the distance between the Fresnel lens and the lamp dependent. If the lamp filament is located in the focal point of the Fresnel lens, then results in the narrowest light bundling. This is a quasiparalleler beam path, also called spot, receive. By shortening the Distance between the Fresnel lens and the lamp becomes the opening angle the exiting light beam steadily increased. Thereby becomes a diverging ray, which is also called Flood is received.

adversely on such headlamps, however, is the poor light output especially in their spot position, since here only a relatively small Solid angle range of the lamp is detected by the Fresnel lens. In addition, it is disadvantageous that the spherical Reflector reflected light to a large extent the lamp filament meets again, there is absorbed and the lamp filament additionally heating up.

From the DE 39 19 643 A1 is a headlight with a reflector, a shutter and a Fresnel lens known. With the headlamp the illumination is changed by an adjustment of the light source. This causes a brightness change of the light. A distance regulation between vertex and reflector and between the diaphragm and the reflector serves to regulate the brightness.

From the DE 34 13 310 A1 is a headlight with a lamp and a reflector or a lamp and a positive lens known. The headlamp further has a lens or a mirror, both of which are positioned at an angle of 45 °. Through the mirror, the light is deflected and through the lens, the light is scattered. By moving the lens different beam angle of the light beam are generated.

The DE 101 13 385 C1 describes a Fresnel lens in which the Fresnel lens is a converging lens whose light source side focal point is in spot position approximately in the reflector 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 spotlight add.

With However, the invention is intended to provide a Fresnel spotlight which has a more compact design and consequently both Space-saving and lighter than the conventional Fresnel lens headlamps is.

These Task becomes surprising simple way with a Fresnel lens according to claim 1 and a lighting set according to claim 19.

By Using a step lens with negative focal length, a can extremely compact design can be achieved, which, for example, in Spot position of the Fresnel lens headlamp essentially only the length of the reflector together with the thickness of the respective used stage lens.

With the inventive Fresnel lens spotlight will significantly improve light efficiency achieved especially in spot, but also in Floodstellung.

At the same time the uniformity of the illuminance is maintained in the entire light field, as this example 7 is shown for both the spot and a Floodstellung.

According to the invention is a ellipsoidal reflector with large aperture. The spot position becomes adjusted by the fact that the lamp filament of a black body radiator, in particular a halogen lamp or the discharge arc of a discharge lamp located in the reflector-side focal point of the ellipsoid and the reflector-distant second focal point of the ellipsoid in about the negative or virtual reflector distant focal point of the Fresnel lens arranged is.

The Reflected light from the reflector is before entering the negative lens almost complete focused on the reflector distant focus of the ellipsoid. The in the reflector-side focal point located lamp coil or the discharge arc becomes after passing through the Fresnel lens imaged into the infinite and their light is thus in one transferred almost parallel beam.

The reflected light essentially no longer hits the lamp filament or the discharge arc. The virtual negative focus of the Fresnel lens falls with the reflector distant focal point of the reflector ellipsoid together and thus creates an extremely compact design.

at more appropriate The choice of the aperture angle of reflector and Fresnel lens becomes reflected by the reflector light almost completely from the stepped lens detected and as a narrow spot light beam after emitted in front.

The Luminous efficiency is thus considerably higher than in a conventional one Fresnel spotlight.

The opening angle of the emerging from the Fresnel lens light beam can in a first embodiment almost arbitrarily enlarged be by the lamp position with respect to the reflector on the one hand and the distance of the Fresnel lens to the reflector on the other hand in a suitable Way is changed.

In order to the good features of conventional Fresnel spotlights in terms of uniformity the illuminance should remain these changes in distance by a suitably chosen forced coupling respectively.

A embodiment the invention is that the ellipsoidal reflector of a metallic or transparent material. To be favoured Glass and polymeric materials or plastics used which advantageously be coated with metal, such as aluminum can.

alternative or additionally becomes a for producing a reflective surface of the two or both surfaces of the reflector with a System optically thinner Layers provided. This will be advantageously visible Radiation shares reflected and the invisible parts, in particular Thermal radiation components, pass through.

A Another preferred embodiment of Invention includes a metallic coating on one or both main surfaces of the reflector.

In Another alternative embodiment, the reflector also a metallic reflector which is both uncoated and dielectric or metallic may be coated to the desired spectral and to provide corrosion properties.

A preferred embodiment The invention comprises a Fresnel lens in which the light reflecting surface of the reflector is structured in a light-scattering manner and none, one or two surfaces the Fresnel lens are structured light scattering. This comes to a fixed proportion of the superposition of scattered light geometrically-optically imaged light, which is an illustration of the Avoids lamp in the light field. Preferably, the reflector has for this purpose Partial surfaces or Facets that make it possible its light-scattering components defined to calculate and manufacture.

With increasing reduction of the light source, about on the important Field of digital projection or high power discharge lamps but one can always be stronger more pronounced middle dark area occur, which with scattering facilities within the reflector not or only with large light losses can be compensated. Even the conventional ones, to avoid one Illustration of the emission center of the light source used scattering Facilities provide only limited, if any, remedy, as well as here in each position of the Fresnel lens at least the dark one central opening cone must be homogeneously illuminated. But this is exactly what happens especially in the spot position to large light losses, because here but only a dark area with a very small opening angle exists in the conventional Fresnel lenses with diffusing facilities nevertheless the full area of the Fresnel lens is used to scatter the light field.

The Inventors have found that these high light losses are surprising easy way can be avoided. Especially advantageous It is here, if the Fresnel lens has a lens, which are formed in a particularly preferred circular and only is arranged in the center of the Fresnel lens.

at this embodiment can in each position of the Fresnel lens spotlight the dark areas be very effectively avoided in the middle of the illumination field, but it does not come to the high light losses in the spot position of the reflector.

In surprising Way it turns out that the geometric-optical beam path of the light emerging from the reflector at the location of the Fresnel lens exactly then illuminates a smaller area when the required proportion is increased in scattered light.

This effect, the inventors have made use of, with the invention an automatic to create beautiful or adaptive light mixing system, which synchronously in addition to the adjustment of the Fresnel spotlight only those scattered light component to geometrically-optically imaged light mixes, which is required for this position.

This Light mixing ratio, which almost optimally to the respective required light distributions can be adapted, hereinafter abbreviated only referred to as mixing ratio.

By This automatic light mixing system will essentially work for any position the reflector the right mixing ratio and thus always a very homogeneously illuminated light field created without this, however unnecessary Scatter losses occur.

in this connection can by choosing the diameter of the integrated lens in relation to to the remaining area the Fresnel lens the mixing ratio the full surface illuminated stage lens can be defined and can by the Scattering properties of the negative lens of the opening angle of the scattered Be defined light.

Further can on the integrated lens itself the scattering effect vary so that, for example, in the middle of the lens more scattering Regions and arranged at the edge of less scattering areas are. This will make you stronger focused beam in addition expanded and then it can be extremely wide illumination angle realize.

alternative Also, the edge of the diffuser can not only be designed to end abruptly but it can this steadily in its scattering effect be designed decreasing and still below or above the Step lens extend. This allows further adjustments to the position-dependent mixing ratios make.

It Reference is made to the application filed on the same day of the same applicant entitled "Optical Arrangement with Fresnel Lens", the disclosure of which is hereby incorporated by reference by reference completely is also made to the disclosure of the present application.

According to the invention is the Using the headlight for Architecture, medicine, movie, stage, studio and photography and in a flashlight.

The Lens may in the preferred embodiments both at the Be arranged Lichteintritts- as well as on the light exit side. Furthermore, there is the advantageous possibility of spreading discs to arrange the light entrance and at the light exit side. at this latter embodiment can also different scattering, for example, locally different scattering, Spreading discs are used.

The The invention will be described with reference to preferred embodiments and with reference on the attached Drawings described in more detail.

It demonstrate:

1 an embodiment of the Fresnel spotlight in the spot position, wherein the reflektorferne focal point of the reflector is superimposed approximately with the right side virtual focus of the Fresnel lens,

2 in the 1 shown embodiment of the Fresnel spotlight in a first Floodstellung, the reflector distant focus of the reflector is arranged approximately in a reflector near surface of the Fresnel lens,

3 in the 1 shown embodiment of the Fresnel spotlight in a second Floodstellung with larger opening angle, the reflector distant focus of the reflector is imaged in front of the reflector remote surface of the Fresnel lens by the Fresnel lens,

4 in the 1 shown embodiment of the Fresnel spotlight in a third Floodstellung with even larger opening angle than in the second Floodstellung, the reflector distant focal point of the reflector is imaged in front of the reflector remote surface of the Fresnel lens by the Fresnel lens and the light source is moved from the reflector near focus on the reflector,

5 in the 1 shown embodiment of the Fresnel spotlight in the second Floodstellung with larger opening angle, wherein by means of an auxiliary reflector, a further part of the light is first directed into the reflector and from this into the Fresnel lens,

6 a negative stage lens with centrally arranged diffuser,

7 an opening angle-dependent logarithmic representation of the light intensity of the Fresnel spotlight in its spot and in one of its Floodstellungen.

8th a characteristic curve for the forced coupling between the sizes a and b, wherein the parameters of Fresnel lens, elliptical reflector and Illuminants are selected by way of example.

detailed Description of preferred embodiments

at The following detailed description assumes that same reference numerals the same or equivalent elements in the respective various embodiments.

The following will be on 1 which shows an embodiment of the Fresnel spotlight in spot position. The Fresnel lens headlamp 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 with negative refractive power, preferably a biconcave step lens.

In 1 is the reflector-distant focal point F2 of the ellipsoidal reflector 1 approximately with the right-hand virtual or negative focal point F3 of the Fresnel lens 3 superimposed.

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

The distances a between step lens 3 and leading edge of the reflector 1 and b between the lamp 2 and vertex of the reflector 1 are also in 1 shown.

The spot position is adjusted by the fact that the lamp filament or the discharge arc of the lamp 2 essentially in the reflector-side focal point F1 of the reflector ellipsoid 1 is arranged.

That of the reflector 1 Reflected light is in this position almost completely on the reflector distant focus F2 of the ellipsoid 1 directed. The right-hand negative or virtual focus F3 of the Fresnel lens 3 then coincides with the focal point F2 of the reflector ellipsoid 1 together.

It is in 1 in the near field also recognize how the opening 5 inside the reflector 1 in the parallel beam path of the light field 4 as a dark area 6 effect.

Inside the Fresnel lens 3 is a circular, centrally arranged diffuser 7 provided, which generates a defined scattered light ratio and a defined opening angle of the scattered light. This results in a defined mixing ratio of the scattered light relative to that through the Fresnel lens 3 provided geometrically-optically imaged light.

As an alternative to this embodiment of the lens 7 In a further embodiment, the scattering effect changes along the radius of the lens 7 in a steady manner, leaving in the middle of the lens 7 more scattering areas and at their abruptly ending edge less scattering areas are arranged.

In yet another alternative embodiment, the edge of the lens is 7 not only abruptly ending but it is this trained in its scattering effect steadily decreasing and this can also extend under or over the step lens.

hereby become system dependent further adjustments to the position-dependent mixing ratios made, so that the expert always an optimal mixing ratio for a homogeneous illuminated light field or also defined for light fields produced locally higher intensities can provide.

It is off 1 Furthermore, to recognize that in the spot position, only a small part of the total light, through the lens 7 occurs.

Through the lens 7 it comes to a very homogeneous illumination, as in 7 , which shows an opening angle-dependent logarithmic representation of the luminous intensity of the Fresnel spotlight, for the spot position with the line 8th is reproduced.

2 shows the in 1 illustrated embodiment of the Fresnel spotlight in a first Floodstellung, wherein the reflektorferne focal point F2 of the reflector 1 approximately in a reflector-like surface of the Fresnel lens 3 is arranged.

in this connection the value of the shift a is compared to the spot position a mechanical guide defined changed.

The structure basically corresponds to the in 1 explained construction of the Fresnel spotlight.

However, it is off 2 clearly recognize that both the opening angle of the exiting light beam 4 as well as the dark area 6 has increased.

Because in this position, however, a very high proportion of the light is only on a very small area in the middle of the lens 7 can strike, this area can be designed so that its before downward lobe approximately in the dark area 6 Compensated in the far field or far range in the desired manner. It was also on 7 referenced, which the lighting conditions with the line 9 exemplifies a Floodstellung reproduces.

The following will be on 3 referenced in the 1 illustrated embodiment of the Fresnel spotlight in a second Floodstellung with even larger opening angle than in 2 shows, wherein the reflektorferne focal point F2 of the reflector 1 in front of the reflector surface of the stepped lens 3 through the Fresnel lens 3 is shown.

This is a larger area of the lens 7 as in 2 Shown by illuminated and its total scattering behavior can be adapted to the conditions of this Floodstellung.

A renewed widening of the beam 4 you get like in 4 illustrated alternatively or in addition to the Floodstellung 3 by changing the distance b of the lamp 2 to the reflector 1 , With displacement of the lamp 2 to the reflector 1 towards the light beam leaving the reflector is bundled again stronger and it comes out after emerging from the Fresnel lens 3 to increased exit angles.

The change the distance a and also the distance b may in further embodiments For example, by hand, mechanically, electrically, electronically or take place in combination with each other, for which purpose an axial guidance of the optical components can be used.

In order to the regularity the illuminance is maintained, the distance changes take place in a particular preferred embodiment however, by a suitably chosen forced coupling which the change of a and b in a defined ratio puts.

That over the Forced coupling defined ratio the sizes a and b is integrated by the parameters used by Fresnel lens Diffuser, elliptical reflector and luminous body determined. The parameters include the dimensions, geometry, structure and optical Properties of the individual components.

in the special includes for the Fresnel lens whose optical diameter, whose focal length, whose Vault, whose light-scattering structure and its arrangement on the front and / or back the Fresnel lens; For the lens integrated in the stage lens whose optical Diameter, its light-scattering structure and their arrangement; for the elliptical Reflector whose optical diameter, whose curvature, whose focal length, whose Surface structure, the distance between the two foci and the diameter of the lamp leadthrough and for the illuminant its shape, dimensions, position and the type of filament, for example formed as a metal vapor discharge lamp, Halogen lamp or CDM lamp. Other influences not explicitly mentioned here Parameters are possible.

As an example 8th a characteristic curve for the forced coupling between the sizes a and b. The parameters used of stepped lens, elliptical reflector and luminous body are exemplified: stepped lens: with 160 mm optical diameter and 108.7 mm negative focal length, integrated lens with 28 mm diameter in the center (honeycomb : Diagonal 3.4 mm, radius 4 mm, 3 ° twisted), back with light-scattering structure; Elliptical reflector: with 160 mm optical diameter and 35 mm focal length, 160 mm distance between the two focal points, lamp guide with 30 mm diameter; Illuminant: cylinder in axial position, about 7.2 mm long, diameter about 2.6 mm.

A change the parameter leads to a change of the over the forced coupling defined ratio of the quantities a and b. This results in a change the functional relationship of the characteristic characterizing the positive coupling.

Another preferred embodiment shows 5 , In this embodiment, except for an additional auxiliary reflector 18 essentially corresponds to the embodiments described above, is by the auxiliary reflector 18 Light of the lamp 2 which is located in 5 would spread to the right and the reflector 1 would not reach through reflection in the reflector 1 directed. As a result, both the light, which only by way of example through the beam path 19 is shown and without the auxiliary reflector would not contribute to the lighting would be used but it can also be used directly in the Fresnel lens 3 entering part of the light can be better used for the desired light distribution.

The shape of the auxiliary reflector 18 is advantageously chosen so that at this reflected light does not return to the lamp of the lamp 2 , For example, a coil or discharge zone, enters and this additionally heated unnecessarily.

Alternatively, the auxiliary reflector 18 on the inside and / or outside of the glass body of the lamp 2 be upset. For this purpose, the glass of the lamp body can be shaped accordingly to achieve the desired directivity for the reflected light.

6 shows an example of a step lens 3 with diffuser 7 as used by the invention. The Fresnel lens 3 has a transparent body 10 and a Fresnel ring system 11 with annular lens sections 11 . 12 . 13 , within which the circular diffuser 7 is arranged.

The diffuser 7 is defined or has facets 15 . 16 . 17 with in many areas exactly definable scattering behavior, which in the German patent application DE 103 43 630.8 of the same applicant with the title "diffuser" are described, which was deposited on 19 September at the German Patent and Trademark Office. The disclosure of this application is also incorporated by reference in its entirety to the disclosure content of this application.

The However, the invention is not limited to these embodiments described above limited by spreading discs.

Especially Advantageously, the above-described Fresnel spotlight finds its use in a lighting set along with one opposite the State of the art much smaller electrical power supply or ballast. This Power supply can be opposite the prior art same useable light output both electrically be designed as mechanically smaller because the inventive Fresnel lens spotlight on a much higher Luminous efficiency features. Consequently less weight is needed and claimed during transport and storage less storage space.

hereby but also, especially when using cold light reflectors reduces the overall thermal load on the illuminated persons and objects.

Further can the Fresnel spotlight according to the invention to increase the light output can also be used advantageously in flashlights, where available electrical energy is in principle more limited.

1

reflector

2

lamp

3

fresnel lens

4

leaking light beam

5

Opening in the reflector 1

6

dark Area

7

diffuser

8th

intensity distribution in spot position

9

intensity distribution in flood position

10

body

11

Fresnel lens ring system

12

annular lens sections

13

ditto.

14

ditto.

15

facet

16

ditto.

17

ditto.

18

auxiliary reflector

19

by Auxiliary reflector reflected beam path

Claims (21)

Fresnel lens spotlight with adjustable opening angle of the emerging light beam with a, preferably ellipsoidal reflector, a lamp and at least one Fresnel lens, characterized in that the Fresnel lens is a lens with negative focal length, thus a negative lens with a virtual focal point. Fresnel lens according to claim 1, characterized characterized in that the Fresnel lens has a virtual focus having a reflector having a reflector of the reflector, especially in spot position of the Fresnel spotlight, superimposable is. Fresnel spotlight according to claim 1 or 2, characterized in that the step lens is preferably biconcave Negative lens is. Fresnel lens headlight according to claim 1, 2 or 3, characterized in that the step lens is a double lens comprising chromatically corrected imaging properties. Fresnel spotlights with the characteristics of the generic term of claim 1, in particular according to one of the preceding claims through a stepped lens with integrated lens. Fresnel lens headlamp according to claim 5, characterized characterized in that the lens is circular and in the center the Fresnel lens is arranged and defines a light mixing system, which is the proportion of the scattered light relative to the proportion of the geometric-optical imaged light, thus the light mixing ratio, depending changed from the position of the Fresnel lens headlamp. Fresnel spotlight, characterized that the distance (a) between the Fresnel lens and reflector to the distance (b) between lamp and reflector in accordance with the opening angle to be set of the light beam emerging from the headlight in a defined geometric dependence variable is. Fresnel spotlight according to claim 7, characterized characterized in that the distance (b) is adjustable by that the lamp with regard to the vertex of the reflector is slidably disposed. Fresnel spotlight according to one of the preceding Claims, characterized in that the reflector of a metallic or transparent, preferably dielectric material glass and / or Plastic exists. Fresnel spotlight after a protruding Claims, wherein at least one of the two main surfaces of the reflector with a System optically thinner Layers is provided. Fresnel spotlight according to one of the preceding Claims, characterized in that at least one of the two main surfaces of the Reflector with metal, preferably aluminum, coated. Fresnel spotlight according to one of the preceding Claims, wherein the light-reflecting surface of the reflector, preferably subareas or having facets, is structured in a light-scattering manner and none, one or two surfaces the Fresnel lens in addition are structured to diffuse light scattering. Fresnel spotlight according to one of the preceding Claims, characterized in that the step lens is a negative lens, like these in the German application filed on the same day of the same applicant entitled "Optical Arrangement with Fresnel Lens" is. Fresnel spotlight according to one of the preceding Claims, characterized in that the reflector, the Fresnel lens and / or the lens are coated at least on one side. Fresnel lens headlamp according to claim 14, characterized in that the coating of the stepped lens is a dielectric Interference layer system comprising the spectrum of the passing Light changed. Fresnel spotlight according to one of the preceding Claims, characterized in that the lamp is an incandescent lamp, in particular a halogen lamp, a light emitting diode, a light emitting diode array or a Gasentladunsglampe is. Fresnel spotlight according to one of the preceding Claims, characterized in that an auxiliary reflector between step lens and reflector is arranged. Fresnel spotlight according to one of the preceding Claims, characterized in that the step lens is preloaded on its surface, is preferably thermally biased. Lighting set comprising a Fresnel spotlight according to one of the preceding claims from 1 to 18 and a associated electrical power supply or ballast. Use of the Fresnel lens after a the claims 1 to 18 and a lighting set according to claim 19 for medicine, Architecture, film, stage, Studio and photography. Flashlight comprising a Fresnel spotlight according to one of the preceding claims from 1 to 18.