EP2271872A1

EP2271872A1 - Illumination unit

Info

Publication number: EP2271872A1
Application number: EP09734593A
Authority: EP
Inventors: Jörg Erich SORG; Stefan Gruber
Original assignee: Osram Opto Semiconductors GmbH
Current assignee: Ams Osram International GmbH
Priority date: 2008-04-25
Filing date: 2009-04-16
Publication date: 2011-01-12
Also published as: WO2009129784A1; US8731392B2; KR20170018106A; DE102008020817A1; US20110188846A1; CN106090846A; CN101965479A; KR20110006649A

Abstract

The present application describes an illumination unit (1) for an optical recording appliance (13), which illumination unit (1) has a light source (2) for generating radiation and a partially reflective element, which is arranged downstream of the light source (2) in a main emission direction (H) and divides a space into a first half-space, which faces the light source (2), and a second half-space, which is remote from the light source (2), wherein the partially reflective element at least partially transmits the radiation coming from the light source (2) from the first half-space and at least partially reflects the external radiation coming from an opposite direction from the second half-space.

Description

description

light unit

In the present case, a lighting unit is specified, which is particularly suitable for use in an optical recording device.

This patent application claims the priority of German Patent Application 10 2008 020 817.5, the disclosure of which is hereby incorporated by reference.

Commercially available mobile phones increasingly have integrated cameras and thus serve as optical recording devices. To improve the recording quality, the mobile phone may have a flashlight, which is arranged next to a camera lens. As a further feature, a mirror for self-portraits can be provided in addition to the flash and the camera lens. A corresponding mobile telephone is shown in FIG. Such

Mobile phone has a special component for each function.

The flashlight may, for example, comprise a radiation-generating semiconductor chip with a converter which converts the generated radiation at least partially into radiation of a longer wavelength. In such a flash, the various components are recognizable to an observer.

In the present case, a problem to be solved is to specify a lighting unit whose components are not recognizable in detail. This object is achieved by a lighting unit according to claim 1.

Advantageous embodiments and further developments of the lighting unit are the subject of the dependent claims.

According to a preferred embodiment, the lighting unit has a light source for generating radiation and a partially reflecting element arranged downstream of the light source in a main emission direction, which subdivides a space into a first half space facing the light source and a second half space facing away from the light source, wherein the partially reflecting element the radiation coming from the first half-space from the light source is partially transmitted and the outer radiation coming from an opposite direction from the second half-space is partially reflected. In particular, the transmitted radiation illuminates the second half space.

According to a first variant, the partially reflecting element is a partially transmissive mirror. For example, the partially transmissive mirror may be a coating containing a metal or metal compound or consisting of a metal or metal compound. Further, the partially transmissive mirror may be a dichroic mirror. The reflected external radiation can be collimated by means of the partially transmissive mirror, so that an object located in the second half-space is imaged by the partially transmissive mirror.

According to a second variant, the partially reflecting element is designed such that an object located in the second half-space is not imaged. In particular, points the partially reflecting element according to the second variant has a facet structure. Preferably, an object facing the object located in the second half-space surface of the partially reflecting element is formed with a plurality of optical structure elements. The optical structural elements may be, for example, concave or convex-shaped lenses. The partially reflecting element advantageously has a regular arrangement of a plurality of optical structural elements.

With such a lighting unit with a partially reflecting element, the view of the light source can be blocked for an observer in the second half space with advantage. Thus, the external appearance of the light source can be hidden or masked.

Nevertheless, it is possible that radiation generated by the light source passes into the second half space and illuminates it.

According to a preferred embodiment, the lighting unit has a beam-shaping optical element with a radiation entrance surface and a radiation exit surface. Preferably, the radiation entrance surface is disposed on a side of the beam-shaping optical element facing the light source, while the radiation entrance surface is arranged

Radiation exit surface is located on a side facing away from the light source.

The radiation exit surface of the beam-shaping optical element can be convexly curved. The convex arched

Radiation exit surface can cause a collimation of the emitted light from the light source in different directions radiation. For example, by means of the jet-forming optical element, a radiation characteristic can be achieved, which allows a homogeneous illumination of a given limited field in the second half space. The boundaries of the field are especially where the radiation intensity drops to a value that is less than 50% of an average value assumed by the radiation intensity within the field. Homogeneous illumination is preferably given when the deviation from the mean radiation intensity within the limited field is not more than 20%.

According to a preferred embodiment, the beam-shaping optical element is arranged between the light source and the partially reflecting element.

In particular, the partially reflecting element can be arranged on the radiation exit surface of the beam-shaping optical element. As a result, the radiation emitted by the light source initially interacts with the beam-shaping optical element before impinging on the partially reflective element.

The partially reflecting element may have a curvature corresponding to the radiation exit surface. Furthermore, the partially reflecting element may have a planar shape if the radiation exit surface is planar.

Depending on the application, the semitransparent mirror can be curved convexly, concavely arched or flat. For an optical recording device such as a mobile phone with an integrated camera, a convex-curved semitransparent mirror is particularly useful for recording a self-portrait suitable. In particular, not only the light source can be masked by means of the partially transparent mirror, but also an object located in the second half-space can be reflected and imaged. By means of the partially transparent mirror can thus at the same time two

Functions are fulfilled. This advantageous development can be realized in a particularly simple manner in that the partially transmissive mirror is applied in the form of a coating to the convexly curved radiation exit surface and thus assumes the shape of the radiation exit surface.

In the case of a facet structure, the optical structure elements can be arranged along the curved or planar radiation exit surface, so that the partially reflecting element is also one of the

Radiation exit surface corresponding vault 'or has a planar shape. The arrangement of optical structure elements, which is in particular a lens arrangement, may be formed integrally with the optical element.

However, it is also conceivable that the partially reflecting element is formed as a separate element and is arranged downstream of the beam-shaping optical element in the main emission direction.

According to a preferred embodiment, the optical element on the radiation entrance side as a convex or concave lens, Fresnel lens, TIR (Total Internal Reflection) - lens or as an array of single lenses, which may be arranged irregularly formed. This improves the

Radiation coupling into the optical element and the guidance of the radiation in the optical element. In particular, this is arranged the partially reflecting element on the Strahlunsaustrittsseite.

According to a further embodiment, the partially reflecting element can be arranged on the radiation inlet surface of the beam-shaping optical element. Consequently, in this variant, the radiation emitted by the light source strikes the partially reflecting element before interacting with the beam-shaping optical element.

The embodiment in which the partially reflective element is applied to the radiation exit surface and the embodiment in which the partially reflective element is applied to the radiation entrance surface have various advantages. In the first case, the partially reflecting element preferably directly adjoins the surroundings, that is to say the partially reflecting element is uncovered and therefore has a substantially unimpeded reflectivity. In the second case, the partially reflective element is covered by the beam-shaping optical element. Although this can reduce the reflectivity. However, this protects the partially reflecting element from the environment, which counteracts a reduction in the reflectivity due to environmental influences, for example by scratches on the surface.

Preferably, the partially transmissive mirror is one on the radiation entrance surface of the beam-forming optical

Elements applied coating. In this way, the partially transmissive mirror can assume the shape of the radiation entrance surface. Accordingly, the partially reflecting element provided with a facet structure can be mounted on the

Radiation entrance surface are arranged and in this way assume the shape of the radiation entrance surface.

In a partially transmissive mirror, a concavely curved radiation entrance surface is particularly advantageous. Because this can be achieved for a reflecting object in the second half space, the mirror effect of a convex mirror, which is particularly suitable for use in an optical recording device such as a mobile phone with integrated camera.

Furthermore, the radiation exit surface may be convex in this variant convex or flat. The planar design has the advantage, when using the lighting unit in an optical recording device, that the surface of the lighting unit is flush with the outer wall of the recording apparatus.

According to a preferred embodiment, a refractive index-adapting material is arranged between the light source and the radiation entrance surface, which in particular has a refractive index which is between the refractive index of the refractive index

Semiconductor chips and the refractive index of the optical element is located. As a result, the refractive index jump at the transitions can be reduced, which leads to lower reflections and thus to a reduction of radiation losses.

According to an advantageous embodiment of the partially transmissive mirror is partially reflecting in a wide wavelength range. Suitable materials are here in particular metals or metal compounds. For example, the partially transmissive mirror may contain or consist of Ag or Au. Furthermore, the partially transmissive mirror may contain or consist of a metal oxide, in particular aluminum oxide or titanium oxide. Decisive influence on the partial transmission has in this embodiment, the layer thickness, which is preferably lnm to 20nm.

Alternatively, the partially transmissive mirror may be partially reflective in a limited wavelength range. In this case, a dichroic mirror is advantageously used. This has a sequence of dielectric layers with alternately different refractive indices. For example, a dichroic mirror may be used if the light source has visible colorations that an observer would find disturbing upon direct viewing of the light source, but which can be hidden by a suitable dichroic mirror. For by means of the dichroic mirror, that color component in the external radiation can be attenuated by reflection, which gives the color its special color, so that the color is no longer visible to the observer.

The reflectivity of the partially transparent mirror is preferably in a range between 5% and 80%.

According to a preferred embodiment, the light source has a radiation-emitting semiconductor chip. The semiconductor chip may in particular be made of materials based on nitride compound semiconductors, which in the present context means that an active epitaxial layer sequence from which the semiconductor chip is formed, or at least one layer of which is a nitride

Ill / V compound semiconductor material, preferably

Al _n Ga _1n In ₁ . _n . _m N, where O ≦ n ≦ l, O ≦ m ≦ l and n + m <1.

By means of a conversion element, which is arranged downstream of the semiconductor chip in the main emission direction, a part of the radiation emitted by the semiconductor chip can be wavelength-converted, so that this radiation fraction has a greater wavelength than the original radiation. As a result, the light source emits mixed-color total radiation.

For example, the semiconductor chip can emit blue light, which is partially converted into yellow light by means of the conversion element, so that the light source emits white light. In this case, when the light source is switched off directly by the conversion element, a yellow color impression is created by an observer. The light source thus has a yellow coloration for the observer. As already mentioned, the coloring can advantageously be masked by means of the partially reflecting element.

According to a preferred embodiment, the light source is a flashlight, that is, the light source is as a

Lighting device is formed which generates a flash of light when taking an object in the second half-space, which provides the necessary illumination of the object. The flashlight may comprise, for example, a radiation-emitting semiconductor chip of the type described above or one

Gas discharge lamp, for example a xenon lamp. It should be noted that the light source can emit electromagnetic radiation in the visible, near infrared or ultraviolet spectral range.

For example, a lighting unit with a light source that emits radiation in the infrared spectral range can be used to advantage for an autofocus device in a mobile phone.

According to an advantageous embodiment, an optical recording device, in particular a mobile phone with integrated camera, a lighting unit of the type mentioned above and a camera lens. If the partially reflecting element is a partially transmissive mirror, then the lighting unit is arranged next to the camera lens such that an object reflected in the partially reflecting mirror is located in the receiving area of the camera lens. This embodiment advantageously allows the inclusion of self-portraits.

It should be noted that the optical recording apparatus may be, for example, a camera.

Advantageous embodiments of a lighting unit and of an optical recording apparatus according to the present application will be explained in more detail below with reference to FIGS. 1 to 6.

Show it:

FIG. 1 shows a schematic perspective illustration of a section from a first exemplary embodiment of a lighting unit, FIG. 2 is a schematic perspective view of a detail of a second exemplary embodiment of a lighting unit;

FIG. 3 shows a schematic perspective view of a lighting unit according to the first or second exemplary embodiment,

FIG. 4 is a schematic cross-sectional view of a portion of an embodiment of an optical recording apparatus;

FIG. 5 shows a schematic illustration of a top view of the embodiment of an optical recording device shown in FIG. 4,

Figure 6 is a schematic representation of a plan view of a conventional mobile phone.

The same or equivalent elements are provided in the figures with the same reference numerals.

In Figures 1 to 6, the partially reflective element described is a partially transmissive mirror, however, the partially transmissive mirror may also be replaced by a partially reflective element having a facet structure as described above.

Figure 1 shows a first embodiment of a lighting unit 1 with a light source 2 and a partially transparent mirror 3, which is the light source 2 in a Haupabstrahlrichtung H downstream. The partially transparent mirror 3 divides a room into one of Light source 2 facing half-space (not marked in Figure 1) and in a light source 2 remote from the half-space (not marked in Figure 1). Between the partially transparent mirror 3 and the light source 2, a beam-shaping optical element 4 is arranged, with which the radiation generated by the light source 2 interacts before it impinges on the partially transmissive mirror 3.

The partially transmissive mirror 3 is applied in the form of a coating to a radiation exit surface 4 a of the beam-shaping optical element 4. Preferably, there are no further layers between the

Radiation exit surface 4a and the semi-permeable

Mirror 3, which may consist of a metal layer, a metal oxide layer or a sequence of alternating refractive index dielectric layers. The

For example, coating can be applied to the

Radiation exit surface 4a are vapor-deposited or sputtered.

The radiation exit surface 4a is convexly curved, which is preferably a collimation of the passing

Radiation leads. By applying the partially permeable

Mirror 3 on the radiation exit surface 4a, this also has a convex curvature.

On the other hand, as shown in FIG. 1, the radiation entrance surface 4b facing the radiation exit surface 4a may be concavely curved. This improves the radiation coupling into the beam-shaping optical element 4. The beam-shaping optical element 4 has, on a side facing the light source 2, a spacer 4c whose height is selected such that the light source 2 has a suitable distance from the beam-shaping optical element 4. At the same time, the spacer 4c serves as

For the spacer 4c is inserted into a carrier 5, so that the spacer 4c is seated on planar support surfaces 5a and 5b of the carrier 5 and disposed within side surfaces 6a and 6b of the carrier 5, which from the Level of the support surfaces 5a and 5b are bent out.

The carrier 5 has a first sub-carrier with the carrier surface 5a and the at least one side surface 6a and a second sub-carrier with the carrier surface 5b and the at least one side surface 6b. Between the two sub-carriers, a gap 7 is present. The two sub-carriers are held together by an insert 8 in the carrier 5.

Preferably, the two sub-carriers are formed from an electrically conductive material, so that a first electrical contact is formed by the first sub-carrier and a second electrical contact of the light source 2 is formed by the second sub-carrier. The insert 8 advantageously contains an electrically insulating material, so that the first subcarrier is electrically insulated from the second subcarrier.

The light source 2 has a radiation-emitting semiconductor chip and a semiconductor chip arranged on the

Conversion element on. In particular, the semiconductor chip emits radiation in the short-wavelength visible spectral range, such as blue light. Furthermore, that can Conversion element to convert part of the radiation into yellow light, so that the lighting unit emits white light in total.

Advantageously, yellow dyeings on the

Chip surface, which are caused by the conversion element, are masked by the partially transmissive mirror 3, so that an observer in the second half space does not perceive these stains. However, the partially transmissive mirror 3 does not prevent radiation portions of the blue and yellow light from the light source 2 from entering the second half space. Thus, the second half-space can be illuminated by the mixed-color total radiation.

By means of the beam-shaping optical element 4, a radiation characteristic can be achieved, which is particularly suitable for illuminating a limited field. For example, the limited field may be the face of an observer in the second half space.

When using the light unit 1 shown in Figure 1 in an optical recording device, the light source 2 is advantageously a flash, which illuminates the face of the observer sufficiently.

The partially transparent mirror 3 makes it easier for the observer to record a self-portrait. If the observer sees his reflection in the mirror, he is in the area of a camera lens and can be sure that a corresponding image will be photographed.

The lighting unit 1 is constructed to save space by the integrated light source 2 and the integrated mirror 3. The illustrated in Figure 2 second embodiment of a lighting unit 1 is similar in construction as the first embodiment. Here, too, the beam-shaping optical element 4 is fastened to the carrier 5 by means of the spacer 4c inserted into the carrier 5. The light source 2 is arranged on the carrier 5 and is located in an opening of the insert 8 provided for the light source 2.

In contrast to the first embodiment, however, the partially transparent mirror 3 is not subordinate to the beam-shaping optical element 4 in the main emission H, but is located in the main emission H in front of the beam-shaping optical element 4. ^•

In particular, the partially transmissive mirror 3 is applied to the radiation entrance surface 4b of the beam-forming optical element 4. This arrangement has the advantage that the partially transparent mirror 3 is protected against reflection-reducing effects from the environment such as scratches.

The radiation entrance surface 4b is concavely curved so that the same mirror effect as in the first embodiment is produced for the external radiation impinging on the partially transparent mirror 3 from the second half space, namely the mirror effect of a convex mirror.

To reduce radiation losses is advantageous between the light source 2 and the radiation entrance surface

4b, a refractive index adjusting material (not marked in FIG. 2) is arranged. In particular, that fills Refractive index adapting material from the cavity between the beam-shaping optical element 4 and the carrier 5 from.

FIG. 3 shows how the lighting unit 1 according to the first or second exemplary embodiment can look from the outside. The beam-shaping optical element 4, as shown, form a housing cover and the carrier 5 form a housing bottom of the lighting unit 1. Here, the spacer 4c serves as a side wall surrounding the light source 2 on all four sides. The spacer 4c can have indentations on all four sides, in which the side surfaces 6a, 6b engage. The arrangement described advantageously prevents slippage of the beam-shaping optical element 4 relative to the carrier 5.

FIG. 4 shows a detail of an optical recording device with a lighting unit 1 of the type described above. The optical recording device has a first wall 10 and a second wall 11, wherein in the first wall 10, a recess 9 is provided for the lighting unit 1. The lighting unit 1 is arranged so that the beam-shaping optical element 4 projects into the recess 9.

To increase the radiation intensity, the recess may be formed as a reflector, i. the at least one side wall facing the beam-shaping optical element 4, which delimits the recess, has a comparatively high reflectivity.

The electrical connection of the lighting unit 1 via the second wall 11, which is electrically connected to the carrier 5 of the lighting unit 1. For the electric Connection provide contact means 12, which are preferably spring elements. The spring elements have the advantage that for different distances between the first and the second wall 10, 11, the same contact means 12 can be used.

If the contact means 12 have a small diameter, a relatively low heat removal takes place by the contact means 12. Additional cooling can advantageously take place via the thermally conductive side surfaces 6a, 6b.

FIG. 5 shows an optical recording device 13 which may be constructed as shown in FIG. For example, the optical recording device 13 is a mobile phone. In the first wall 10, a camera lens 14 is provided in addition to the light unit 1.

The light unit 1 with integrated light source and integrated semitransparent mirror meets two

Functions. On the one hand, an object / subject, which is located in front of the camera lens 14 and is to be scanned, can be sufficiently illuminated by the lighting unit 1, which in particular has a flashlight. On the other hand, the subject can correctly position himself to take a self-portrait by means of the lighting unit 1.

FIG. 6 shows a conventional mobile telephone 13 which, on the other hand, provides separate elements for the two functions, a light source 2 and a mirror 15.

As is apparent from Figures 5 and 6, the lighting unit 1 is relatively space-saving. In addition, the partially transmissive mirror contained in the lighting unit 1 masks the Light source, so that any disturbing colorations of the light source are covered.

The invention is not limited by the description with reference to the embodiments. Rather, the invention encompasses any novel feature as well as any combination of features, including in particular any combination of features in the claims, even if this feature or combination itself is not explicitly stated in the claims or exemplary embodiments.

Claims

claims

A light-emitting unit (1) for an optical recording device (13) comprising a light source (2) for generating radiation and a partially reflecting element arranged downstream of the light source (2) in a main emission direction (H) and occupying a space in a first light source ( 2) facing half-space and a second light source (2) facing away from the half-space, wherein the partially reflecting element coming from the light source (2) from the first half-space

Radiation transmitted at least partially and at least partially reflects the coming from an opposite direction of the second half-space outside radiation.

2. lighting unit (1) according to claim 1, wherein the partially reflecting element is a partially transparent mirror (3).

3. The lighting unit (1) according to claim 2, wherein the partially transmissive mirror (3) contains a metal or a metal compound, consists of a metal or a metal compound or is a dichroic mirror.

4. lighting unit (1) according to claim 1, wherein the partially reflecting element is an arrangement of a plurality. having optical structural elements.

5. lighting unit (1) according to claim 4, wherein the optical structure elements are concave or convex lenses.

6. lighting unit (1) according to any one of the preceding claims, comprising a beam-shaping optical element (4) having a radiation exit surface (4a) and a radiation entrance surface (4b).

7. lighting unit (1) according to claim 6, wherein the radiation exit surface (4a) of the beam-shaping optical element (4) is convexly curved or flat.

8. lighting unit (1) according to claim 7, wherein the partially reflecting element on the

Radiation exit surface (4a) of the beam-shaping optical element (4) is arranged and one of the radiation exit surface (4a) has corresponding curvature.

9. lighting unit (1) according to any one of claims 6 to 8 in the back reference to claim 2 or 3, wherein the partially transmitting mirror (3) one on the

Radiation exit surface (4a) applied coating or a separate downstream of the radiation exit surface (4a) element.

10. Light unit (1) according to any one of claims 6 to 9, wherein the optical element (4) is formed on the radiation entrance side as a convex or concave lens, Fresnel lens, TIR lens or arrangement of single lenses.

11. Lighting unit (1) according to claim 6 or 7, wherein the partially reflecting element on the

Radiation entrance surface (4b) of the beam-shaping optical element (4) is arranged.

12. Light unit (1) according to claim 11, wherein the radiation entrance surface (4b) is concavely curved and the partially reflecting element has a curvature corresponding to the radiation entrance surface (4b).

13. lighting unit (1) according to claim 11 or 12 in the back reference to claim 2 or 3, wherein the partially transmissive mirror (3) on the radiation entrance surface (4b) of the beam-forming optical element (4) applied coating.

14. Optical recording device (13) with a lighting unit (1) according to one of the preceding claims and a camera lens (14), wherein the lighting unit (1) next to the camera lens (14) is arranged.