Optocoupler with Side-Emitting Electromagnetic Radiation Source

Abstract

An optocoupler is provided and which includes a side-emitting electromagnetic radiation source configured to emit electromagnetic radiation at a side wall, and an electromagnetic radiation detector configured to detect at least part of the emitted electromagnetic radiation.

Claims

1. An optocoupler, comprising: a side-emitting electromagnetic radiation source configured to emit electromagnetic radiation at a side wall; and an electromagnetic radiation detector configured to detect at least part of the emitted electromagnetic radiation.

2. The optocoupler of claim 1, wherein the electromagnetic radiation source is a laser diode.

3. The optocoupler of claim 1, wherein the electromagnetic radiation detector is a photodiode.

4. The optocoupler of claim 1, wherein the electromagnetic radiation source and the electromagnetic radiation detector are electrically decoupled from each other.

5. The optocoupler of claim 1, wherein the electromagnetic radiation source is configured to emit electromagnetic radiation substantially only at the side wall.

6. The optocoupler of claim 1, wherein the electromagnetic radiation detector is configured to detect electromagnetic radiation at a first main surface of the electromagnetic radiation detector.

7. The optocoupler of claim 6, wherein the electromagnetic radiation detector is configured to detect electromagnetic radiation substantially only at the first main surface.

8. The optocoupler of claim 6, wherein the first main surface is an upper main surface of the electromagnetic radiation detector.

9. The optocoupler of claim 1, further comprising: a control unit coupled with the electromagnetic radiation detector and configured to carry out a control task based on the detected electromagnetic radiation.

10. The optocoupler of claim 9, wherein the control task is a switching task.

11. The optocoupler of claim 1, further comprising: an optically transparent encapsulant in which at least part of the electromagnetic radiation source and at least part of the electromagnetic radiation detector are embedded.

12. The optocoupler of claim 11, wherein the optically transparent encapsulant is a transparent gel.

13. The optocoupler of claim 1, further comprising: a housing body surrounding at least part of the electromagnetic radiation source and at least part of the electromagnetic radiation detector, and having a reflective interior surface configured to reflect at least part of the electromagnetic radiation emitted by the electromagnetic radiation source.

14. The optocoupler of claim 13, wherein the reflective interior surface is configured to reflect and direct at least part of the electromagnetic radiation onto the electromagnetic radiation detector.

15. The optocoupler of claim 1, wherein at least one of: the electromagnetic radiation source is configured to emit red light; the optocoupler is configured as a relay; the electromagnetic radiation source is configured to emit at least 60% of an intensity of the emitted electromagnetic radiation at the side wall within an angular range of not more than 45 around an axis perpendicular to the side wall; the side-emitting electromagnetic radiation source is configured to emit substantially monochromatic electromagnetic radiation, and the electromagnetic radiation detector is configured to detect substantially only within a narrow wavelength band around a wavelength of the emitted substantially monochromatic electromagnetic radiation; the side-emitting electromagnetic radiation source and the electromagnetic radiation detector are arranged side-by-side.

16. The optocoupler of claim 1, further comprising: a source carrier on which the electromagnetic radiation source is mounted; and a detector carrier on which the electromagnetic radiation detector is mounted.

17. The optocoupler of claim 16, wherein at least one of: the source carrier and the detector carrier are leadframes or are separated sections of a common leadframe; the source carrier and the detector carrier are arranged at a same vertical level; the source carrier is arranged at a higher vertical level than the detector carrier so that the light-emitting side wall is arranged at a higher vertical level than a side wall of the electromagnetic radiation detector; at least part of at least one of the source carrier and the detector carrier is slanted so that the electromagnetic radiation source and the electromagnetic radiation detector are tilted with respect to each other.

18. The optocoupler of claim 1, further comprising: a deflector arranged to deflect at least part of the emitted electromagnetic radiation onto the electromagnetic radiation detector.

19. The optocoupler of claim 18, wherein at least one of: the deflector is mounted on a detector carrier on which the electromagnetic radiation detector is mounted; the electromagnetic radiation detector is arranged between the electromagnetic radiation source and the deflector; the deflector has a deflecting surface angled with a deflection angle in a range between 30 and 60, with respect to incident electromagnetic radiation to be deflected onto the electromagnetic radiation detector; the deflector is soldered onto a detector carrier on which the electromagnetic radiation detector is mounted.

20. A method of operating an optocoupler, the method comprising: emitting electromagnetic radiation at a side wall of a side-emitting electromagnetic radiation source; and detecting at least part of the emitted electromagnetic radiation by an electromagnetic radiation detector.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The accompanying drawings, which are included to provide a further understanding of exemplary embodiments and constitute a part of the specification, illustrate exemplary embodiments.

[0043] In the drawings:

[0044] FIG. 1 shows a cross-sectional view of an optocoupler according to an exemplary embodiment.

[0045] FIG. 2 shows a cross-sectional view of an optocoupler according to another exemplary embodiment.

[0046] FIG. 3 shows a cross-sectional view of an optocoupler according to still another exemplary embodiment.

[0047] FIG. 4 shows a cross-sectional view of an optocoupler according to yet another exemplary embodiment.

[0048] FIG. 5 shows a cross-sectional view of an optocoupler according to still another exemplary embodiment.

DETAILED DESCRIPTION

[0049] The illustrations in the drawings are schematic.

[0050] Before describing further exemplary embodiments in further detail, some basic considerations of the present inventors will be summarized based on which exemplary embodiments have been developed.

[0051] According to an exemplary embodiment, an optocoupler (preferably embodied as solid-state relay) may be provided which may use a side-emitting arrangement. Thus, a side-emitting electromagnetic radiation source (for instance a laser diode) may be implemented instead of a light-emitting diode (LED) based front-to-front arrangement. By taking this measure, exemplary embodiments may provide an improved directional optical transmission.

[0052] Solid-state relays may use one more optocouplers for providing a galvanic separation of electrical potentials. On one side, an emitting device may be provided for emitting light, on the other side a photodetector may be provided for detecting that light and reacting with an electrical change in parameters (for example resistance) or generating (for instance in the presence of a solar cell) to trigger a secondary power device which switches the actual solid-state relay.

[0053] In all cases, a good optical coupling between the light generation and the light detection may be advantageous, as the amount of light detected at the detector may be correlated to the switching speed.

[0054] An exemplary embodiment provides an architecture capable of improving this optical coupling. Instead of a front-side-emitting LED, such an exemplary embodiment may use a side-emitting device, for instance a laser diode.

[0055] Exemplary embodiments may provide an optocoupler having a highly efficient low loss coupling between the input side (i.e. the side-emitting electromagnetic radiation source) and the output side (i.e. the electromagnetic radiation detector). Descriptively speaking, the emission characteristic of the side-emitting electromagnetic radiation source may be precisely defined, i.e. at its vertical side wall, so that a defined irradiation direction is obtained. Hence, it is possible to arrange the electromagnetic radiation detector with its light sensitive surface in accordance with the emission direction of the side-emitting electromagnetic radiation source, to thereby obtain a highly efficient optical coupling between the source side and the detector side. In other words, the radiation path may be adjusted directly from a left-hand side to a right-hand side of the optocoupler. To further increase the transmission efficiency, it is possible to slightly tilt the electromagnetic radiation detector with respect to the emitting side wall of the electromagnetic radiation source. Said tilting may be for instance in an angular range between 10 and 50, in particular in a range between 20 and 40, preferably around 30.

[0056] FIG. 1 shows a cross-sectional view of an optocoupler 100 according to an exemplary embodiment. The optocoupler 100 functions as a solid-state relay.

[0057] The illustrated optocoupler 100 comprises a side-emitting electromagnetic radiation source 102 for emitting electromagnetic radiation 132 at its side wall 104. The electromagnetic radiation source 102 may be a laser diode configured for emitting substantially monochromatic or at least narrow bandwidth light, preferably red light. Further preferably, the electromagnetic radiation source 102 may be configured for emitting electromagnetic radiation 132 only at its side wall 104 (i.e. at its vertical surface on the right-hand side according to FIG. 1), and not at any one of its main surfaces (i.e. the two opposing horizontal surfaces of the electromagnetic radiation source 102 according to FIG. 1) or its other side walls.

[0058] An electromagnetic radiation detector 106 may be provided in the optocoupler 100 for detecting emitted electromagnetic radiation 132 which has propagated up to a light-sensitive surface of the electromagnetic radiation detector 106. The electromagnetic radiation detector 106 may be a photodiode with a light-sensitive upper main surface. Thus, said electromagnetic radiation detector 106 is configured for detecting the electromagnetic radiation 132 for example only at its upper main surfaces 108 according to FIG. 1.

[0059] As shown, the side-emitting electromagnetic radiation source 102 and the electromagnetic radiation detector 106 are arranged side-by-side (rather than vertically stacked) so that the electromagnetic radiation 132 emitted by the electromagnetic radiation source 102 propagates substantially horizontally up to the electromagnetic radiation detector 106.

[0060] The electromagnetic radiation source 102 and the electromagnetic radiation detector 106 are galvanically separated, i.e. electrically insulated with respect to each other and are coupled by the optical link provided by the propagating electromagnetic radiation 132.

[0061] As shown in FIG. 1 as well, the optocoupler 100 comprises a planar plate shaped metallic source carrier 116 on which the electromagnetic radiation source 102 is mounted, for instance by soldering or sintering. Moreover, a planar plate shaped metallic detector carrier 118 is provided on which the electromagnetic radiation detector 106 is mounted, for instance by soldering or sintering. By an electrically conductive connection element 134, such as a bond wire or bond ribbon or alternatively a clip, an upper main surface of the electromagnetic radiation source 102 is electrically connected to the source carrier 116. Correspondingly, an upper main surface of the electromagnetic radiation detector 106 is electrically connected to a control unit 110 (described below in further detail) by an electrically conductive connection element 136, such as a bond wire or bond ribbon or alternatively a clip. For example, the source carrier 116 and the detector carrier 118 may be two separate metallic carriers (for instance two leadframes) or may be separated sections of a common metallic carrier (such as a common leadframe). Such a leadframe may for instance be made of copper and may be a patterned or stamped metal plate. Source carrier 116 and detector carrier 118 may be electrically decoupled.

[0062] As already mentioned, the optocoupler 100 also comprises control unit 110 coupled with the electromagnetic radiation detector 106 and configured for carrying out a control task (in particular switch task) based on the signal content of the detected electromagnetic radiation 132. The control unit 110 may be a semiconductor chip or an arrangement of semiconductor chips and may be electrically coupled with the electromagnetic radiation detector 106 for further processing the detected signals after converting the detected electromagnetic radiation 132 into an electric signal.

[0063] As shown as well in FIG. 1, the optocoupler 100 comprises an optically transparent encapsulant 112, such as a transparent gel, in which the electromagnetic radiation source 102 and the electromagnetic radiation detector 106 are embedded in such a way that the electromagnetic radiation propagates within the optically transparent encapsulant 112 with low losses.

[0064] An opaque housing body 130 surrounding part of the electromagnetic radiation source 102 and part of the electromagnetic radiation detector 106 has a reflective interior surface 114 configured for reflecting (preferably for totally reflecting) electromagnetic radiation 132 emitted by the electromagnetic radiation source 102. An exterior surface of the optically transparent encapsulant 112, which corresponds to the reflective interior surface 114 of the housing body 130, is configured for reflecting the electromagnetic radiation 132, partially or entirely. More specifically, the reflective interior surface 114 may be configured for reflecting and directing the electromagnetic radiation 132 onto the electromagnetic radiation detector 106. Housing body 130 may be a casing or a further encapsulant.

[0065] The electromagnetic radiation source 102 embodied as laser diode may emit narrow bandwidth light, which can be chosen in accordance with the absorption properties of the transparent gel constituting encapsulant 112, for instance in order to fit into the best possible transmission window. Preferably, red light may be used, since this may allow implementing components of the optocoupler 100 with reasonable effort.

[0066] The embodiment of FIG. 1 shows how electromagnetic radiation 132, such as visible light in the red wavelength range, is emitted by the electromagnetic radiation source 102. In the emitted electromagnetic radiation 132, an information is included which is to be transmitted to the electromagnetic radiation detector 106. The corresponding electromagnetic radiation 132 is emitted exclusively via a vertical side wall 104 of the plate-shaped electromagnetic radiation source 102. As shown in FIG. 1, the propagation path up to the light-sensitive surface 108 on an upper side of the plate-shaped electromagnetic radiation detector 106 is short and thus the emission efficiency high. Furthermore, the reflection at the curved surface 114 between the optically transparent encapsulant 112 and the housing body 130 further increases the amount of electromagnetic radiation 132 propagating up to the light-sensitive upper main surface 108 of the electromagnetic radiation detector 106. The electric connection between the source carrier 116 and the electromagnetic radiation source 102 is accomplished by the electrically conductive connection element 134. Thus, an electric signal may be conducted along the source carrier 116 via the electrically conductive connection element 134 up to the electromagnetic radiation source 102 where the electric signal is converted into the electromagnetic radiation 132. The latter is then transmitted to the electromagnetic radiation detector 106 for detection. The detected electromagnetic radiation 132 is then converted into an electric signal in the electromagnetic radiation detector 106. The latter electric signal is then forwarded via further electrically conductive connection element 136 to control unit 110. It is alternatively also possible that the detector carrier 118 also carries the electric signal.

[0067] As shown in FIG. 1 as well, the electromagnetic radiation source 102 may be configured for emitting a major portion of for instance at least 60% of an intensity of the electromagnetic radiation 132 via its side wall 104 within a narrow angular range a of for instance 30 around an axis extending horizontally according to FIG. 1 and perpendicular to the side wall 104. With such a configuration of focusing the major part of the emitted electromagnetic radiation intensity within a narrow cone having an axis perpendicular to the emitting side wall 104, a highly efficient transfer of electromagnetic radiation 132 from the side-emitting electromagnetic radiation source 102 to the electromagnetic radiation detector 106 may be promoted.

[0068] FIG. 2 shows a cross-sectional view of an optocoupler 100 according to another exemplary embodiment.

[0069] The embodiment of FIG. 2 differs from the embodiment shown in FIG. 1 in that, according to FIG. 2, the source carrier 116 and the detector carrier 118 are arranged at the same vertical level 120. Since both source carrier 116 and detector carrier 118 are at the same vertical level, they can be realized by a common patterned or structured metal plate.

[0070] According to FIG. 2, one leadframe constituents the source carrier 116 and the detector carrier 118 which are therefore located at the same vertical level, although being electrically decoupled from each other. Hence, a very simple embodiment is shown in FIG. 2 where both emitter (i.e. electromagnetic radiation source 102) and detector (i.e. electromagnetic radiation detector 106) are located at the same vertical level. This embodiment relies on diffusion of the side emission in the transparent gel which forms optically transparent encapsulant 112 in order to illuminate the front-side, i.e. light-sensitive surface 108, of the electromagnetic radiation detector 106.

[0071] FIG. 3 shows a cross-sectional view of an optocoupler 100 according to still another exemplary embodiment.

[0072] The embodiment of FIG. 3 differs from the embodiment shown in FIG. 2 in that, according to FIG. 3, the source carrier 116 is arranged at a higher vertical level 120 than the detector carrier 118. As a result, the light-emitting side wall 104 is arranged at a higher vertical level than a facing side wall 105 of the electromagnetic radiation detector 106.

[0073] Thus, FIG. 3 shows source carrier 116 and detector carrier 118 embodied as two parallel leadframes at different height levels. If the side emitter is slightly elevated as shown in FIG. 3, an even better geometric coupling and illumination capture can be obtained.

[0074] FIG. 4 shows a cross-sectional view of an optocoupler 100 according to yet another exemplary embodiment.

[0075] According to FIG. 4, a part of the detector carrier 118 is slanted (for instance by bending a metal plate) so that the electromagnetic radiation source 102 and the electromagnetic radiation detector 106 are tilted with respect to each other.

[0076] Descriptively speaking, the source-facing end section 107 of detector carrier 118 is bent for providing a face-to-face leadframe architecture for improving optical transmission efficiency. Thus, the advantages achievable by the described side emission can be combined with the illustrated advantageous tilting of at least one of the involved elements (i.e. electromagnetic radiation source 102, electromagnetic radiation detector 106, source carrier 116 and detector carrier 118).

[0077] The optical efficiency in the transmission geometry according to FIG. 4 is highly advantageous, since the detector carrying portion of the detector carrier 118 is slanted. Consequently, the electromagnetic radiation detector 106 can be attached or mounted on the detector carrier 118 so that the slanted upper detecting surface 108 of the electromagnetic radiation detector 106 is properly oriented with respect to emitting side wall 106 of the electromagnetic radiation source 102. Thus, as shown, the emitted electromagnetic radiation 132 may propagate substantially horizontally from side wall 104 to surface 108.

[0078] FIG. 5 shows a cross-sectional view of an optocoupler 100 according to still another exemplary embodiment.

[0079] The optocoupler 100 according to FIG. 5 comprises a deflector 122 arranged for deflecting part of the emitted electromagnetic radiation 132 onto the electromagnetic radiation detector 106, to thereby increase the portion of the emitted electromagnetic radiation 132 which can be detected on the light-sensitive surface 108 of the electromagnetic radiation detector 106. As shown, the deflector 122 is mounted in a simple way on detector carrier 118 on which also the electromagnetic radiation detector 106 is mounted. The electromagnetic radiation detector 106 is thus arranged in a horizontal direction between the electromagnetic radiation source 102 and the deflector 122. The illustrated deflector 122 has a deflecting surface 166 being angled with a deflection angle =45 with respect to said part of the incident electromagnetic radiation 132 to be deflected onto the electromagnetic radiation detector 106. Preferably, the deflector 122 may be made of a solderable material and may be soldered onto detector carrier 118 on which the electromagnetic radiation detector 106 is mounted.

[0080] Hence, FIG. 5 shows a reflector or deflector 122 on the receiving leadframe side. This configuration with laser diode may result in a highly directional illumination. 45-angled deflector 122 can be used particularly advantageous to further increase illumination capture. Deflector material is preferably made from a solderable material and may be attached similar to a clip.

[0081] By the arrangement of the deflector 122 vertically protruding beyond the electromagnetic radiation detector 106, horizontally propagating light originating from the side wall 104 of the electromagnetic radiation source 102 and propagating horizontally may be deflected efficiently onto the light sensitive upper main surface 108 of the electromagnetic radiation detector 106, to thereby further improve the optical coupling efficiency.

[0082] It should be noted that the term comprising does not exclude other elements or features and the a or an does not exclude a plurality. Also, elements described in association with different embodiments may be combined. It should also be noted that reference signs shall not be construed as limiting the scope of the claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.