Medical Light

Abstract

The invention relates to a medical lamp (100), comprising an illumination unit (10), the illumination unit (10) comprising a light emitting device (20) and an optical device (30) for generating a light field (200) in an object plane (O), wherein the light emitting device (20) is formed by a substantially point-shaped LED light source (21) and the optical device (30) comprises a plate-shaped collimator (40) and a cover plate (50). The collimator (40) comprises a central region (42) provided with a light refraction structure (43) on the side facing away from the LED light source (21) and an outer region (46) surrounding the central region (42) and provided with a structure (48) designed for total reflection on the side facing the LED light source (21), wherein the cover plate (50) is provided with a lens structure, which comprises a plurality of individual lenses each designed to project light emitted by the collimator (40) and entering the lens onto the object plane. The rear side of the central region of the collimator facing the LED light source is provided with a plurality of partial surfaces (45, 145) which are inclined relative to the plane (E3) of the collimator (40) and thus relative to the object plane (O) in order to expand the light field (200) asymmetrically in one direction.

Description

Technical Field

[0001] The present invention relates to a medical lamp, in particular to a dental treatment lamp for performing intraoral lighting of an operating area. Background Art

[0002] In order to ensure the quality of medical treatment, it is essential to fully illuminate the inspection point or treatment point. Therefore, medical lamps are designed to illuminate the inspection point or treatment point with an optimized light field, which facilitates the inspection and / or treatment.

[0003] In the case of dental lights, the characteristics of this light field are defined by various standards. One of these standards is EN ISO 9680, according to which, for example, the color rendering index (CRI) is greater than 85, there is a minimum illumination of 15,000 lux, and the light field has a color temperature between 3,600 and 6,400 Kelvin. Furthermore, in order to avoid irritation or even eye damage to the patient, it is stipulated that the light field is sufficiently strongly attenuated in the edge region so that a strictly defined space around the treatment point is illuminated in the object plane.

[0004] A lamp that meets the above requirements is known, for example, from EP2469159B1 of the applicant. This lamp has a plurality of lamp units, each of which has a separate light source and a separate optical unit. The light of the light source of the lamp unit, which is realized by means of a plurality of LEDs, is influenced by the optical unit so that a predetermined, usually approximately hexagonal, area is illuminated at a certain distance in front of the lamp in the so-called object plane. The plurality of lamp units of this known lamp are now constructed and positioned so that they jointly illuminate the corresponding areas in the object plane, thereby producing a uniformly illuminated light field as a whole. If in this case, for example, the light of a single lamp unit is shielded by the doctor's arm or in other ways, the light field illumination is still performed as before by other unshielded lamp units. This ensures that a substantially shadow-free illumination of the area to be examined is obtained.

[0005] The above-mentioned known lamps have repeatedly proven themselves in practice. However, the production of such lamps is associated with a relatively complex assembly of the individual components, since exact alignment of the individual lamp units relative to one another is necessary to achieve a uniformly illuminated light field. The consequence of this is that brightness variations or color variations occur in the edge regions of the light field, which is undesirable.

[0006] Another problem is that the alignment of the mutually matched individual light units results in the corresponding light beams only being accurately superimposed at a fixed defined distance from the lamp. As a result, the desired homogeneous illumination of the light field is mainly obtained in a specific plane in front of the lamp. In contrast, if there are deviations from this ideal distance, the quality of the light field deteriorates.

[0007] Often, provision is made in practice to place the lamp at a fixed predetermined distance from the area to be inspected. This is not always possible, however, and it would therefore be desirable for the light field quality to be less strongly dependent on the distance of the lamp from the area to be illuminated.

[0008] Furthermore, a lamp for general lighting is known from US 2007 / 0147041 A1, in which the light of the light source is used for uniform illumination of a light field. In this case, the optical system used consists of a plate-shaped collimator and a plate arranged downstream of the collimator, which is provided with a lens-type structure, by which a relatively simple structure is achieved overall, whereby a symmetrically illuminated light field is obtained.

[0009] As mentioned in the introduction, the light field should be relatively strictly defined to avoid dazzling, for example, patients to be examined. This means that the illumination actually only occurs in certain predetermined areas; however, it has been shown that excessive brightness differences can have a fatiguing effect on the observer, because the adaptation function of the human eye is overstrained in this way. Summary of the invention

[0010] The invention is based on the object of providing a medical lamp which is optimized in the above-mentioned aspects.

[0011] This object is achieved by a medical light, in particular a dental treatment light.

[0012] The essential difference of the lamp according to the invention with respect to the solution known from EP2469159B1 is that the lamp now has a single lighting unit with a single essentially point-shaped LED light source. In this case, this can be a single LED or a compact LED cluster. However, a plurality of lighting units are not provided, which then have to be complicatedly assembled and matched and aligned with each other as described above in order to obtain an effective uniform illumination of the light field. Instead, the light emitted by the single point-shaped LED light source is influenced in a specific way with the help of an optical device to obtain a uniform and uniform illumination of the light field, but the illumination of the light field is not so strongly dependent on the distance of the area to be illuminated from the lamp. In this case, the optical device has a collimator and a cover plate, both components being equipped with light-guiding structures and components in a specific way in order to allow an optimized illumination of the light field to be achieved despite the compact structure.

[0013] Furthermore, in contrast to the solutions of EP 2 469 159 B1 or US 2007 / 0147041 A1, it is also provided that the brightness gradient in the edge region of the light field is additionally influenced, otherwise the light field is illuminated homogeneously as already mentioned. For this purpose, the optical device is designed such that the light field expands asymmetrically in one direction.

[0014] The invention therefore proposes a medical lamp, in particular a dental treatment lamp, for intraoral illumination of an operating area, which has a lighting unit having a lighting device and an optical device for generating a light field in an object plane. The lighting device is formed in this case by a substantially point-shaped LED light source and the optical device has a plate-shaped collimator and a cover plate.

[0015] - wherein the collimator has a central region provided with a light refraction structure on a side facing away from the LED light source and an outer region surrounding the central region and provided with a structure designed for total reflection on a side facing the LED power source, and

[0016] - wherein the cover plate is provided with a lens structure having a plurality of individual lenses, each lens being designed to project light emitted by the collimator and entering the lens onto the object plane.

[0017] The rear side of the central region of the collimator facing the LED light source is provided with a plurality of partial surfaces which have an inclination relative to the collimator plane and thus to the object plane in order to expand the light field asymmetrically in one direction.

[0018] The two components of the optical system are therefore designed in a special way in order to influence the light emitted by the LED light source in an optimized manner. In this case, the design of the collimator of the invention takes into account the special composition of the light emitted by the white LED light source depending on the light emission angle. A known phenomenon of white LEDs is that the light emitted substantially perpendicularly to the LED surface usually has a higher color temperature and therefore has a slight blue component, while the light emitted strongly laterally has a lower color temperature and therefore appears slightly yellow. The design of the collimator of the invention takes this effect into account and ensures, on the one hand, the formation of a central light field, which is attributed to the light emitted substantially perpendicularly from the LED light source, and on the other hand, an outer light field, which is formed by the light emitted laterally from the LED light source. Finally, the corresponding superposition of the central light field and the outer light field, which is obtained by the design of the cover plate, ensures that the final light field is actually illuminated uniformly and evenly, and no color changes or color temperature changes occur in the edge area, and the central and outer light fields are achieved by the design of the cover plate. At the same time, the use of a single light source in conjunction with the optical system designed according to the invention ensures that the uniform illumination of the light field is not too strongly dependent on the distance from the lamp, so that the above-mentioned problems known in the prior art are avoided.

[0019] The asymmetrical expansion of the light field according to the invention also has the effect that, for example, the brightness gradient at the upper and lower edges of the light field is influenced, wherein the brightness drop in this edge region is less pronounced, in particular in the lower region, so that a less intense brightness contrast occurs than in the opposite edge region. As a result, undesired glare for the patient in the upper edge region of the light field is still avoided, since there is a clear delimitation of the illuminated area from the surroundings. At the same time, an excessively strong contrast is avoided in the opposite edge region, thereby reducing fatigue for the observer, such as the attending physician.

[0020] An asymmetrical expansion of the light field is thus achieved, since the rear side of the central region of the collimator facing the LED light source is provided with a partial surface which has an inclination compared to the collimator plane and thus to the object plane.

[0021] In particular, it can be provided that at least some of the partial surfaces, preferably all of the partial surfaces, are tilted about an axis which lies in the plane (E3) of the collimator (40) and is substantially perpendicular to the asymmetric expansion direction. As an alternative or additional option for obtaining an asymmetric expansion of the light field, at least some of the lenses forming the lens structure can be tilted relative to the collimator plane about an axis which is aligned substantially perpendicular to the asymmetric expansion direction.

[0022] Preferably, it is provided that the partial surface is formed by strip-shaped surface areas, which each extend substantially perpendicularly to the asymmetric expansion direction along their respective tilting axis. It can also be provided here that the strip-shaped surface areas are concavely curved relative to the asymmetric expansion direction, wherein the strip-shaped surface areas are particularly preferably formed symmetrically relative to a plane that is perpendicular to the collimator plane and is defined by an axis extending parallel to the asymmetric expansion direction. As a result of this measure, a certain expansion of the light field is obtained, viewed in width, but it is now symmetrical.

[0023] As an alternative to the strip-shaped partial surface, it is also conceivable that the partial surface is a tile-shaped partial surface, which covers the rear side of the central area of ​​the collimator facing the LED light source like a matrix. Similar to the concave design of the tile-shaped partial surface described above, it can be provided here that at least some of the tile-shaped partial surfaces are inclined relative to the collimator plane around an axis extending parallel to the asymmetric expansion direction, wherein in particular most of the tile-shaped partial surface is arranged symmetrically relative to a plane perpendicular to the collimator plane and defined by an axis extending parallel to the asymmetric expansion direction. This measure in turn results in a certain expansion of the light field in terms of width.

[0024] The light refraction structure of the central area of ​​the collimator preferably forms a so-called Fresnel structure. It is also preferably provided that the collimator structure designed for total reflection forms another Fresnel structure facing the LED light source, and the Fresnel structure surrounds the central area like a ring in a projection perpendicular to the collimator plane. This design of the collimator structure makes it possible in principle to design it as a plate and still effectively influence the light of the LED light source. In this way, a compact structure of the entire lighting unit can be achieved. In this case, the light refraction structure of the central area of ​​the collimator designed for total reflection and the structure of the outer area may preferably have a common rotational symmetry. It is preferably provided that these structures form an aspherical area.

[0025] The lens of the cover plate also used according to the invention is preferably arranged on the side of the cover plate facing the LED light source. In particular, in the case where the cover plate forms the outer surface of the lamp, it can be provided that the side of the cover plate facing away from the LED light source is designed to be smooth. This prevents dirt particles from accumulating on the lamp surface and thus facilitates its cleaning.

[0026] Similar to the collimator, the lens structure of the cover plate can also have an inner region and an outer region, wherein

[0027] - the lenses in the inner region are designed to project the light emitted by the central region of the collimator onto the object plane in the form of a central light field,

[0028] The lenses of the outer region are designed to project the light emitted by the outer region of the collimator onto the object plane in the form of an outer light field, wherein the central light field and the outer light field preferably overlap substantially completely. In this case, it can be provided that each individual lens of the inner region or the outer region respectively projects the corresponding central light field or outer light field completely. This measure in turn leads to a complete and substantially uniform illumination of the desired area even in the case where part of the light emitted via the lamp cover is blocked, for example, by the arm or head of the attending physician.

[0029] The lenses of the inner region can in this case be essentially square, whereas the lenses of the outer region can have a greater extent in the direction of the axis of the collimator running perpendicularly to the asymmetric direction of extension than in the axis running parallel to the asymmetric direction of extension.

[0030] Ultimately, the invention thus provides a lamp which allows optimal illumination of the treatment area, but in which the light unit has fewer components, which results in simplified production and assembly of the lamp as a whole. In particular, however, the advantage is achieved that the light field illumination quality is less dependent on the distance from the lamp. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be explained in more detail below based on the accompanying drawings. In the drawings:

[0032] Figure 1 A perspective view of a medical lamp is shown, in which a lighting unit designed according to the present invention is used;

[0033] Figure 2 Schematic illustration of the light field obtainable with the aid of the lamp of the invention;

[0034] Figure 3 A diagram showing various components of a lighting unit according to a first embodiment;

[0035] Figure 4 Show Figure 3 An enlarged view of a portion of the collimator;

[0036] Figure 5 Another illustration showing a further enlargement of a partial area of ​​the collimator;

[0037] Figure 6 The front side of the collimator facing away from the LED light source is shown;

[0038] Figure 7 The back side of the collimator facing the LED light source is shown;

[0039] Figure 8 A diagram showing various components of a lighting unit according to a second embodiment;

[0040] Fig. 9 Show Figure 8 An enlarged view of a portion of the collimator in FIG.

[0041] Fig.10 and Fig.11 shows another cross-sectional view of a collimator according to a second embodiment;

[0042] Fig.12 The front side of the collimator facing away from the LED light source according to the second embodiment is shown;

[0043] Fig.13 shows the back side of the collimator facing the LED light source according to the second embodiment;

[0044] Fig.14 The illustration shows a cover plate provided with a lens structure. DETAILED DESCRIPTION

[0045] Figure 1 A perspective view of a medical lamp, in particular a dental treatment lamp, generally designated with reference numeral 100, is shown, with which the operating area of ​​a dental office is to be illuminated. In this case, the lamp 100 is designed according to the invention and is therefore equipped with a lighting unit described in detail below; however, the outer shape of the lamp can of course also be designed differently. In this case, Figure 1The illustrations in are mainly used to indicate planes and directions referred to in the later explanation of optical components of the lighting unit according to the present invention.

[0046] In principle, the lamp 100 has a lamp head 110 which is adjustably arranged on an articulated arm 105 (not shown in more detail) so that it can be aimed at the operating area in a desired manner. The housing 111 of the lamp head 110 in this case has two lateral handles 112 for its adjustability, thereby allowing the lamp 100 to be aimed manually.

[0047] In accordance with Figure 1 In the illustration of , it is assumed that the lamp head 110 is aligned in such a way that the light is directed substantially horizontally along an axis A to an area located in front of the lamp 100 , the axis A corresponding to the main axis of the optical system of the lamp 100 . In this illustration, Figure 1 The plane E2 shown is aligned horizontally, and the plane E1 is shown perpendicular to the plane E2 and extends through the main axis of the optical system A. The two axes I1 and I2 extending in the planes E1 and E2 and the optical axis A are then perpendicular to each other. Of course, as mentioned above, the lamp head 110 can also be pivoted during use so that the plane E2 is not aligned horizontally, but extends obliquely downwards or tilted. This is particularly the case if the lamp 100 is located above a patient in a supine position. However, for the following explanation it is assumed that the plane E2 is aligned horizontally.

[0048] Thus, with the lamp 100 according to the invention, the so-called object plane O (see Figure 1 and Figure 3 ) in a specific area in front of the lamp 100. Figure 1 and Figure 2 Schematically shown is a light field 200. In this case, the object plane O is aligned parallel to the plane E3 of the collimator described in more detail below and together therewith perpendicularly to the optical axis A, and it should be noted that the distance between the plane E3 of the collimator E3 and the object plane O and therefore the distance between the lamp 100 and the light field 200 will in reality be greater than the distance shown. As mentioned above, in the following explanation of the design of the optical components of the lamp 100 it is assumed that the optical axis A extends horizontally and that the object plane O and the plane E3 are therefore vertically aligned. However, depending on the alignment of the lamp head 110 during actual use of the lamp 100, the optical axis A will also have an inclination if necessary or will even point vertically downwards in extreme cases, which then also leads to corresponding changes in the alignment of the various planes.

[0049] In this case, the light field 200 has a slightly circular but essentially rectangular shape, wherein the light field 200 extends further in the horizontal direction along the axis O2 than in the vertical direction along the axis O1. In this case, a special feature according to the invention, as explained in more detail below, is that, due to the special design of the optical device, the light emission of the lamp 100 expands slightly asymmetrically in one direction, in the example shown, in the vertical direction. As in Figure 2 As shown in the schematic diagram of the line of the light field 200 in FIG. 1 , this means that in its upper edge region 201 the light field 200 is strongly delimited relative to the surroundings, so that here there is a high brightness gradient at the transition from the light field 200 to the non-illuminated environment. As mentioned above, this strong delimitation is used to avoid dazzling the patient to be examined, which plays an important role in dental examinations or dental treatments in particular. On the contrary, at the opposite lower side 202, the light emission is preferably slightly expanded, so that there is a smaller brightness gradient here. As a result, the light field 200 expands more gently toward the lower side, thereby reducing the proportion of high brightness contrast in the entire field of view of, for example, the doctor. Since such strong brightness contrasts ultimately require fatigue adaptation of the human eye, this measure results in a more pleasant work for the dentist. However, despite these edge regions, it is stipulated that the light field 200 should be illuminated as uniformly and evenly as possible throughout its entire extension, wherein this occurs essentially independently of the distance from the lamp 100. This effect is achieved by means of the design of the lighting unit according to the invention, as will be explained in more detail below.

[0050] According to the first embodiment, the optical structure of the lighting unit 10 disposed inside the lamp 100 is Figure 3 . The important components are mainly lighting devices 20 in the form of point-shaped LED light sources 21, which are arranged on corresponding circuit boards 22. The LED lighting device 21 forms a substantially point-shaped individual light source. Therefore, it is either a single high-performance LED or a relatively compact LED group consisting of multiple LEDs. In both cases, the LED light source 21 is designed so that it emits white light with a desired color temperature.

[0051] The optical system 30 for influencing the light emitted by the lighting device 20 in a relatively wide angle range consists of two components, a collimator 40 on the one hand and a cover plate 50 downstream of the collimator 40 as seen in the emission direction on the other hand. The cover plate is configured to be slightly curved, in particular slightly concavely curved in the embodiment shown, but can also be flat or of other designs. Both the collimator 40 and the cover plate 50 are composed of a light-transmitting material, in particular a plastic material, which has good light-influencing properties and is resistant to external influences, in particular moisture, etc.

[0052] The present invention provides that the collimator 40 is formed by a one-piece, substantially plate-shaped component, which defines the above-mentioned plane E3 and is divided into two regions. In this case, the first light refraction region 42 is arranged at the geometric center of the collimator 40 and has a light refraction structure 43 on the side facing away from the LED light source 21. The task of the central region 42 is to convert the corresponding light beam into a central light field, which is then emitted via the cover 50.

[0053] An outer region 46 is provided which frames the central region 42, in which the light is deflected by total reflection. In this case, the corresponding structure 48 is located on the side facing the LED light source 21 and generates a second outer light field, which is also emitted via the cover 50. The final desired uniform light field 200 is then obtained by superposition of the central light field and the outer light field, wherein the superposition is obtained by an extended structure described in more detail below, which is located on the side of the cover 50 facing the LED light source 21. By realizing a substantially extended uniformly illuminated surface by means of the lighting device 20 and the associated components 40 and 50 of the optical system 30 as light sources, a defocusing effect of the target light field is advantageously obtained when leaving the optimal imaging distance. In other words, the optical system 30 is constructed in principle so that an exact superposition between the central light field and the outer light field is obtained at a predetermined distance of, for example, 700 mm, so that the target light field is particularly uniformly illuminated. However, if this ideal distance is rejected, the variation obtained in this case with respect to the uniform illumination is not as obvious as in the case of lamps in the prior art. In the distance range between 500 and 800 millimeters, an optimal homogeneous illumination of the light field 200 can still be substantially achieved.

[0054] Can be Figures 4 to 7 The design of the collimator 40 can be seen in FIG. As mentioned above, it is a plastic part that is basically in the form of a plate. Figure 6 and Figure 7 It is shown as being substantially square and is used to convert the light beam emitted by the LED light source 21 in a wide angle range into a substantially parallel light beam. To this end, the surface of the collimator 40 has a specific light-influencing structure, which will be explained in more detail below.

[0055] Thus, a Fresnel-type structure 43 is initially provided in a central region 42 of the collimator 40 on the side facing away from the LED light source 21, which serves to deflect the light beams leaving the collimator 40 by light refraction so that they are aligned substantially parallel to the main optical axis A of the system. Such Fresnel structures are known per se and contribute to being able to reduce the thickness of the corresponding optical component compared to conventional convex lenses. Finally, by means of, in particular, Figure 4 and Figure 5 The sawtooth structure can be seen in the figure to obtain extremely effective confinement of the corresponding light. Figure 6 The shown has rotational symmetry about a center or axis A.

[0056] The collimator 40 also has an outer region 46 surrounding the central region 42 like a ring, which is again provided with a Fresnel-type structure 48, but now on the side facing the illumination device 20. These are also made rotationally symmetrical about the optical main axis A, corresponding to Figure 7 , and are used to influence the more laterally emitted light beams so that they are aligned again parallel to the optical axis A. However, the Fresnel structures 43 of the central region 42 influence the light beams by refraction, while the light beams are influenced by total reflection through the Fresnel structures 48 of the outer region 46. This means that these sawtooth structures are again configured in such a way that the light beams can initially enter the rib-shaped protrusions, but are totally reflected due to the difference in light density between the collimator 40 and the surrounding air, so that they leave the collimator 40 again on the side facing away from the lighting device 20. The alignment of the light parallel to the optical axis A of the system is again ensured by the corresponding inclination of the side walls of the total reflection structure 48.

[0057] The light affected by the collimator 40 in this way is then projected through the cover plate 50 onto the actual light field 200 , wherein this has a lens structure described in more detail below for this purpose, which ultimately results in a superposition of the central light field and the outer light field to achieve a uniform even illumination.

[0058] The cooperation of these components consisting of a compactly designed LED light source 20, a collimator 40 with a light refraction and total reflection structure, and a cover plate 50 initially results in the result that the light field 200 finally obtained has a large brightness gradient in the edge area and is therefore strongly defined relative to the surrounding environment. This is particularly desirable on its upper side, therefore in the direction of the patient's eyes to be examined, in order to avoid glare there. On the opposite side, on the contrary, as described above, there should be a significantly more blurred boundary of the light field 200 in order to obtain a reduction in fatigue of the person performing the treatment. This means that the light field 200 ideally has an asymmetry in one direction, which has a soft attenuation towards the lower side.

[0059] In order to achieve this effect, additional structuring is provided on the rear side opposite the light-refracting structure 43 of the central region 42 and thus on the side of the collimator 40 facing the illumination device 20. This structuring is provided in the following manner: Figures 3 to 7 In the first embodiment shown, the arc segment-shaped independent tiles 45 are formed. Figure 7 As shown, the faceted tiles 45 occupy the entire central area 42 up to the outer structure 46 like a matrix. These faceted tiles 45 have a slight tilt or tilt in order to be able to obtain the above-mentioned unilateral expansion of the light field. In particular for this purpose, the tiles 45 are tilted about a horizontal axis (or generally about an axis lying in the plane of the collimator 40 and substantially perpendicular to the asymmetric expansion direction), that is, in the case shown, they enclose a small angle with the vertical axis I1 or O1 (see Figure 4), so that the light beam entering the collimator 40 is slightly expanded toward the lower side. Figure 4 and Figure 5 As shown, even a slight tilt of the tile 45 results in a reduced brightness gradient in the lower edge region of the light field 200 .

[0060] As an alternative or in addition to the above-described tilting of the tiles 45 about an axis perpendicular to the asymmetric extension direction, it would also be conceivable to tilt the lens structure on the cover plate 50 in a corresponding manner to produce the desired advantageous effect of the asymmetric light field distribution. This will be explained in more detail later.

[0061] In addition, however, the tiles 45 can also be tilted on a vertical axis I1 or O1 (or generally around an axis extending parallel to the asymmetric extension direction of the light field), wherein the tiles are preferably arranged symmetrically about a plane E1, which is perpendicular to the plane E3 of the collimator 40 and is defined by the axis I1 extending parallel to the asymmetric extension direction. The horizontal extension of the central light field 200 is thereby influenced, which ultimately also contributes to a uniform illumination of the light field 200.

[0062] This further tilting of the tiles 45 about the vertical axis (or about an axis extending parallel to the asymmetric extension direction) and the symmetrical design about the vertical plane E1 generally result in an approximately concave design of the surface of the rear side of the central region 42 of the collimator 40 facing the lighting device 20. However, the effect of a slightly or even more uniform illumination of the resulting light field 200 can now also be achieved, since the individual tiles located at the same height are unified to form a larger surface, which then also has a corresponding curvature or bulge. A corresponding embodiment thereof is described in detail in the accompanying drawings. Figures 8 to 13 1 and will be explained hereinafter, wherein similar components carry the same reference numerals.

[0063] Therefore, in the second embodiment, the optical system of the lamp 100 according to the present invention also consists of a plate-shaped collimator 40 and a cover plate 50 with a lens structure downstream of the collimator 40. The collimator 40 again has a central region 42, which is provided with a light refraction structure 43 on the side facing away from the LED light source 21, wherein an outer region 46 surrounding the central region 42 is provided with a structure 48 designed for total reflection on the side facing away from the LED light source 21. In this case, the structure 43 of the central region 42 and the structure 48 of the annular outer region 46 are similar in design and function. Figure 3 and 7 Therefore, these features are the same as those of the first embodiment.

[0064] Figures 3 to 7 The first embodiment of Figures 8 to 13The decisive difference of the second exemplary embodiment is the design of the back side of the collimator 40 opposite the light-refracting structure 43 of the central region 42 , which in the first exemplary embodiment is covered with the above-described tiles 45 in a matrix-like manner.

[0065] In the second embodiment, partial surfaces 145 are provided again, but now the partial surfaces are provided in the form of strip-shaped surface areas 145, each of which extends horizontally (or generally perpendicularly to the asymmetric extension direction) from the left end of the central area 42 to the right end, and the alignment of the lamps corresponds to Figure 1 These strip-shaped surface areas 145 are in turn arranged in such a way that they preferably completely cover the rear side of the central area 42 .

[0066] Similar to the tiles 45, the basic function of the strip-shaped partial surfaces 145 is here primarily to achieve an asymmetric expansion of the light field 200 according to the invention, so that the brightness contrast that occurs on the lower side of the light field 200 or on the side opposite to the patient's eye is smaller than at the opposite edge region. In this case, the strip-shaped partial surfaces 145 are also inclined for this purpose about an axis that is in the plane E3 of the collimator 40 and is substantially perpendicular to the asymmetric expansion direction of the light field 200. Fig. 9 The corresponding cross-sectional view corresponds to the first embodiment Figure 4 145, the beam is affected in a similar manner by the tilt, as shown above in conjunction with Figures 3 to 7 As explained. Fig.10 and Fig.11 The sawtooth-shaped structure of the corresponding surface area of ​​the collimator 40 which generally originates therefrom can also be seen in the two perspective views of the partial section of FIG.

[0067] It is also provided that the strip-shaped surface area 145 is concavely curved relative to the asymmetric expansion direction of the light field 200, wherein the curvature direction is through Fig.11 The extremely exaggerated double arrow is schematically shown in FIG. The concave design of the strip-shaped surface area 145 preferably again results in a symmetrical configuration here with respect to a plane E1 which is perpendicular to the plane E3 of the collimator 40 and is defined by an axis I1 extending parallel to the asymmetric extension direction. Fig. 9 In the cross-sectional view of , the rear end region of the strip-shaped surface region 145 is visible due to the concave curvature.

[0068] The resulting surface design of the rear side of the central region 42 of the collimator 40 corresponds overall to Figures 3 to 7 The surface design of the embodiment of , however, here the individual tiles located at the same height have now been replaced by a maintenance area 145 that extends continuously and stably.

[0069] and Figures 3 to 7 Compared with the first embodiment, Figures 8 to 13The second embodiment of the embodiment of the invention here represents a preferred embodiment, since now the edge at the transition of two adjacent tiles 45 is illuminated. Such an edge is essentially associated with the risk of undesired and uncontrollable light scattering, so that a slightly better control of the light by the collimator 40 can be achieved again by a surface design corresponding to the second embodiment.

[0070] The above measures take into account the fact that the spectrum of the light emitted by the LED light source 21 depends on the emission angle. In particular, the light emitted in the center or at the center is cooler and becomes hotter with increasing emission angle radially outward, which is attributed to the increasing travel length of the blue light emitted by the LED chip through the corresponding color conversion material such as phosphor. Therefore, the light of the central light field and the light of the outer light field will initially have different colors or color temperatures. But in general, uniform illumination is obtained due to the superposition of the two light fields obtained by the cover 50 in the end. The fact that the light refractive structure 43 of the central collimating structure and the surface 48 of the outer collimating structure 46 are constructed as aspherical surfaces also contributes to the intentional thorough mixing of the light field or to obtaining a light field with uniform color. Their shape depends on the distance from the center of the optical axis A of the collimator 40; but as shown in the figure, the two structures generally have rotational symmetry.

[0071] The light beam influenced in this way by the collimator 40 is then finally influenced by the cover plate 50, which is constructed in the same way for both embodiments of the collimator 40. As mentioned above, the cover plate 50 can be constructed slightly concave or can also be flat and have a lens structure on its side facing the LED light source 21. In contrast, the side facing away from the lighting device is preferably made unstructured and therefore smooth, thus allowing easy cleaning, which is advantageous, in particular if the cover 50 simultaneously forms the outer side of the lamp 100.

[0072] Like the collimator 40, the lens structure of the cover plate 50 is also realized in two parts. Figure 8 As shown, in this case again a first central region 52 with an associated first lens 53 and an outer region 56 with an associated second lens 58 are provided. In this case, the two regions of the lens structure correspond to the two regions of the collimator 40. In other words, the light beams influenced by the central region 42 of the collimator 40 will be influenced by the central lens region 52 of the cover, while the light emitted via the outer region 46 of the collimator 40 is influenced by the outer lens structure.

[0073] However, both lens structures 52 and 56 are constructed as microlens arrays and are used to project corresponding partial beams of light onto the area to be illuminated as an extended structure. In this case, the ratio of the height to the width of the individual lenses defines the values ​​of the horizontal and vertical extension of the light field 200, wherein these values ​​are slightly different for the central lens 43 and the outer lenses 58, so that the extensions of the two light fields are slightly different. The end result of these measures is then that the central light field and the outer light field overlap substantially completely within a distance of about 500-800 mm provided for illumination, so that an overall uniformly illuminated light field 200 is obtained.

[0074] In this case, each individual lens of the cover plate 50 projects a complete central light field or outer light field, so that the shielding of individual lenses or parts of the cover plate 50 does not lead to shadows in the light field 200. This also contributes to optimized illumination. In the embodiment shown, the lenses of the outer area have different sizes and shapes compared to the lenses of the central area. In particular, the lenses 53 of the central area 52 are constructed approximately square, while the lenses 58 of the outer area are more like rectangles. However, this is not necessarily the case. It is only decisive that the lenses cause the expansion of the individual light beams to occur in such a way that an overall complete superposition occurs, which leads to a uniform illumination that is essentially independent of the distance from the lamp. As a result, a uniform target light field with the desired properties is obtained.

[0075] In order to obtain the above-mentioned asymmetric light field distribution, it is conceivable that as an alternative or in addition to the tilting of the tiles 45 or the strip-shaped partial surfaces 145, a part or all of the lenses 53, 58 of the lens structure 52 and / or the lens structure 56 are tilted relative to the plane E3 of the collimator about an axis that is aligned substantially perpendicular to the asymmetric expansion direction. This measure also leads to a preferably asymmetric expansion of the light field 200 on its lower side 202, so that a corresponding tilted alignment of the tiles 45 or the strip-shaped partial surfaces 145 can also be optionally omitted.

[0076] Overall, high-quality illumination of the area to be examined or treated can thus be achieved with the lamp according to the invention. The lamp is also distinguished here by its relatively simple structure, which comprises only a few individual components and is significantly less critical than known solutions in terms of exact alignment and positioning of the individual components relative to one another.

Claims

1. A medical lamp (100), comprising a lighting unit (10), the lighting unit (10) comprising a light-emitting device (20) and an optical device (30) for generating a light field (200) in an object plane (O), in, The light-emitting device (20) is formed by a substantially point-shaped LED light source (21), and the optical device (30) has a cover plate (50) and a plate-shaped collimator (40). The collimator (40) comprises a central region (42) and an outer region (46), wherein the central region (42) is provided with a light refraction structure (43) on a side facing away from the LED light source (21), and the outer region (46) surrounds the central region (42) and is provided with a structure (48) designed for total reflection on a side facing the LED light source (21), and The cover plate (50) is provided with a lens structure, wherein the lens structure has a plurality of individual lenses, each of which is designed to project light emitted by the collimator (40) and entering the lens onto the object plane. Its characteristics are: The rear side of the central region (42) of the collimator (40) facing the LED light source (21) is provided with a plurality of partial surfaces (45, 145), which are inclined relative to the plane (E3) of the collimator (40) and therefore relative to the object plane (O) in order to asymmetrically expand the light field (200) in one direction.

2. The medical lamp according to claim 1, characterized in that: At least some of the partial surfaces (45, 145) are inclined about an axis which lies in the plane (E3) of the collimator (40) and is substantially perpendicular to the direction of the asymmetric expansion.

3. The medical lamp according to claim 2, characterized in that: The partial surfaces (145) are formed in strip shape and each extends along its respective inclined axis substantially perpendicular to the direction of the asymmetrical extension.

4. The medical lamp according to claim 3, characterized in that: The strip-shaped surface area (145) is concavely curved with respect to the direction of the asymmetric expansion, wherein the strip-shaped surface area (145) is formed symmetrically with respect to a plane (E1), the plane being perpendicular to the plane (E3) of the collimator (40) and being defined by an axis (I1) extending parallel to the direction of the asymmetric expansion.

5. The medical lamp according to claim 2, characterized in that: The partial surface (45) is tile-shaped and covers the rear side of the central area (42) of the collimator (40) facing the LED light source (21) like a matrix.

6. The medical lamp according to claim 5, characterized in that: At least some of the tile-shaped partial surfaces (45) are inclined relative to the plane (E3) of the collimator (40) about an axis extending parallel to the direction of the asymmetric extension.

7. The medical lamp according to claim 6, characterized in that: A majority of the tile-shaped partial surfaces (45) are arranged symmetrically with respect to a plane (E1) which is perpendicular to the plane (E3) of the collimator (40) and is defined by an axis (I1) extending parallel to the direction of the asymmetrical extension.

8. A medical lamp according to any one of the preceding claims, characterized in that The light refractive structure (43) of the central region (42) of the collimator (40) forms a Fresnel structure.

9. The medical lamp according to claim 8, characterized in that: The structure (48) of the collimator (40) designed for total reflection forms another Fresnel structure facing the LED light source (21).

10. The medical lamp according to claim 9, characterized in that: The light-refractive structure (43) and the structure (48) of the collimator (40) designed for total reflection have a common rotational symmetry.

11. The medical lamp according to claim 8, characterized in that: The light-refractive structure (43) and the structure (48) of the collimator (40) designed for total reflection have aspherical areas.

12. The medical lamp according to claim 1, characterized in that: The optical device (30) is configured to enable the light field (200) projected onto the object plane (O) perpendicular to the optical axis (A) of the lamp (100) to have an extension range of an axis (O2) extending perpendicular to the direction of the asymmetric extension greater than an extension range of an axis (O1) extending parallel to the direction of the asymmetric extension.

13. The medical lamp according to claim 1, characterized in that: At least some of the lenses (53, 58) forming the lens structure are tilted relative to the plane (E3) of the collimator about an axis aligned substantially perpendicular to the direction of the asymmetric extension.

14. The medical lamp according to claim 1, characterized in that: The lens (53, 58) is arranged on a side of the cover plate (50) facing the LED light source (21).

15. The medical lamp according to claim 1, characterized in that: The lens structure of the cover plate (50) has an inner region (52) and an outer region (56), wherein: The lens (53) of the inner region (52) is designed to project the light emitted by the central region (42) of the collimator (40) onto the object plane (O) in the form of a central light field, and The lens (58) of the outer region (56) is designed to project the light emitted by the outer region (46) of the collimator (40) onto the object plane (O) in the form of an external light field, and The central light field and the external light field are substantially completely superimposed.

16. The medical lamp according to claim 15, characterized in that: The lens (53) of the inner region (52) is substantially square, and the lens (58) of the outer region (56) has a larger extension range in the direction of an axis (I2) of the collimator (40) extending perpendicularly to the direction of the asymmetric expansion than in the direction of an axis (I1) of the collimator (40) extending parallel to the direction of the asymmetric expansion.

17. The medical lamp according to claim 1, characterized in that: The medical lamp (100) is a dental treatment lamp used for intraoral lighting of an operating area.

18. The medical lamp according to claim 2, characterized in that: All partial surfaces (45, 145) are inclined about an axis which lies in the plane (E3) of the collimator (40) and is substantially perpendicular to the direction of the asymmetric expansion.

19. The medical lamp according to claim 9, characterized in that: The further Fresnel structure surrounds the central region (42) like a ring in a projection perpendicular to the plane (E3) of the collimator (40).

20. The medical lamp according to claim 14, characterized in that: The side of the cover plate (50) facing away from the LED light source (21) is formed smooth.

21. The medical lamp according to claim 14, characterized in that: The side of the cover plate (50) facing away from the LED light source (21) forms a smooth outer surface of the lamp (100).

22. The medical lamp according to claim 15, characterized in that: Each individual lens (53, 58) of the inner region (52) or the outer region (56) fully projects the corresponding central light field or outer light field, respectively.

Images