Patent Description:
An optocoupler may be an electronic component that transfers electrical signals between two isolated circuits by using light. For instance, an optocoupler may prevent high voltages from affecting the system receiving the signal. A common type of optocoupler may comprise a light-emitting diode and a phototransistor in the same opaque package.

There is still potentially room to improve an optical coupling of an optocoupler. <CIT> discloses a multi-directional optocoupler which comprises light emitting devices, e.g. VCSELs, and light detecting devices, e.g. photodetectors. The light emitting devices are capable of generating a light signal which travels through regions <NUM>, <NUM> towards the light detecting devices. <FIG> discloses a horizontal arrangement, wherein the light emitting devices and the light detecting devices are arranged side by side. <FIG> discloses a vertical (or stacked) arrangement, wherein the light emitting devices and the light detecting devices are arranged superimposed to each other. <CIT> discloses an optocoupler comprising multiple optocoupling stacks. Each optocoupling stack comprises a VCSEL which is directing light to photodetectors arranged below the VCSELs. The optocoupler may comprise an array-like arrangement of a plurality of adjacent optical stacks.

<CIT> discloses a photo coupler comprising a semiconductor laser and a semiconductor light-receiver which are arranged on electrodes which act as carriers and are connected with the electrodes, by wires. A waveguide which comprises a light reflective portion is arranged between the semiconductor laser and the semiconductor light-receiver.

<CIT> discloses an optocoupler which comprises an optical transmitter die which transmits a ray of light onto a surface of an optical receiver die. A first encapsulant and a second encapsulant enclose the optical transmitter die and the optical receiver die. To enable a ray of light which is emitted from a side of the optical transmitter die being received at an upper surface of the optical receiver die, the optical transmitter die is arranged on an elevated portion of a conductive pad.

There may be a need for an optocoupler with improved optical coupling.

According to an exemplary embodiment, an optocoupler is provided which comprises a side-emitting electromagnetic radiation source for emitting electromagnetic radiation at its side wall, and a plate-shaped electromagnetic radiation detector for detecting at least part of the emitted electromagnetic radiation; the opto-coupler further comprises a source carrier on which the electromagnetic radiation source is mounted, and a detector carrier on which the electromagnetic radiation detector is mounted, wherein the electromagnetic radiation detector is configured for detecting electromagnetic radiation at its upper main surface and wherein at least a 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.

According to another exemplary embodiment, a method of operating an optocoupler is provided, wherein the method comprises 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.

According to an exemplary embodiment, an optocoupler is provided which has an electromagnetic radiation source irradiating electromagnetic radiation (such as light) predominantly or completely via its side face. Thus, the side-emitting electromagnetic radiation source may emit electromagnetic radiation to propagate substantially horizontally, rather than via a top or bottom main surface. As a result, an improved optical coupling between such a side-emitting electromagnetic radiation source and an electromagnetic radiation detector arranged side by side with the electromagnetic radiation source may be obtained, since this geometry and configuration enables a direct transmission of electromagnetic radiation along a short propagation path. Contrary to conventional approaches, an electromagnetic radiation beam may thus propagate predominantly horizontally through the optocoupler on its way from the electromagnetic radiation source to the electromagnetic radiation detector. An improved optical coupling between electromagnetic radiation source and electromagnetic radiation detector may therefore result in a more reliable and more failure robust operation of the optocoupler. The latter may for example be embodied as a switching solid-state relay.

In the following, further exemplary embodiments of the optocoupler and the method will be explained.

In the context of the present application, the term "optocoupler" may particularly denote an optoelectronic component which couples two electrically conductive but electrically separated electric circuits with each other by an optical link provided by an electromagnetic radiation beam, such as a light beam. Such an optical coupling may be provided between an electromagnetic radiation source being galvanically separated from or electrically decoupled from an electromagnetic radiation detector.

In the context of the present application, the term "electromagnetic radiation source" may particularly denote a component which is capable of generating and emitting an electromagnetic radiation beam, in particular in a directed way. According to an exemplary embodiment, the electromagnetic radiation source may be configured for emitting an electromagnetic radiation beam propagating along an approximately horizontal rather than vertical direction. For instance, the emitted electromagnetic radiation beam may be a light beam, more particularly a beam of visible light. The electromagnetic radiation source may convert an electric signal to be transmitted to the electromagnetic radiation detector side into an optical signal for transmission via the optic link.

In the context of the present application, the term "electromagnetic radiation detector" may particularly denote an electronic component capable of detecting electromagnetic radiation (such as light) received from the electromagnetic radiation source and converting the signal to which the transmitted electromagnetic radiation relates into an electric signal for further processing on the detector side. For instance, the electromagnetic radiation detector may be configured for detecting electromagnetic radiation in a limited bandwidth, i.e. in a limited range of wavelengths. The emission characteristics of the electromagnetic radiation source and the detection characteristic of the electromagnetic radiation detector may be adjusted to match.

In the context of the present application, the term "side-emitting" electromagnetic radiation source may particularly denote that the surface of the electromagnetic radiation source at which the electromagnetic radiation (such as visible light) is emitted is a (in particular vertically oriented) side wall rather than a (for instance horizontally oriented) main surface. For instance, such an electromagnetic radiation source may be a plate-shaped element or a cuboid element which emits the light along a relatively small side wall rather than along a larger top surface or bottom surface. When the side-emitting electromagnetic radiation source is a laser diode, electromagnetic radiation in an interior of the laser diode may propagate in the laser resonator between an ideal mirror and an intentionally non-ideal mirror. Both the ideal mirror and the non-ideal mirror may be formed by a respective side wall of the laser diode. For example, the non-ideal mirror side wall may have a larger roughness and therefore intentionally reduced reflection capability as compared to the ideal mirror. The electromagnetic radiation propagating between said two side walls may then be emitted predominantly or even exclusively via the non-ideal mirror side wall.

In an embodiment, the electromagnetic radiation source is a laser diode. For example, such a laser diode may be manufactured in semiconductor technology, in particular in silicon technology or gallium arsenide technology. A laser diode may be powered by an electric current and may generate at a pn-junction electromagnetic radiation which can be emitted via a side surface of the laser diode. By taking this measure, a specifically directed electromagnetic radiation beam may be emitted for propagation towards the electromagnetic radiation detector for detection.

As an alternative to a laser diode, the side-emitting electromagnetic radiation source may be embodied in accordance with DLP (Digital Light Processing) technology (for instance implementing micromirrors).

In an embodiment, the electromagnetic radiation detector is a photodiode. A photodiode may be an optical element having a pn-junction and being capable of capturing electromagnetic radiation for transferring it into electric charges, and thus into an electric voltage or an electric current. For example, a light sensitive surface of a (in particular plate-shaped or cuboid) photodiode may be an upper or lower main surface thereof. Thus, a large detection surface is provided by a photodiode.

In an embodiment, the electromagnetic radiation source and the electromagnetic radiation detector are galvanically separated. In the context of the present application, the term "galvanically separated" may particularly denote that the electromagnetic radiation source and the electromagnetic radiation detector are electrically decoupled from each other so that no electric signal can propagate directly from the electromagnetic radiation source to the electromagnetic radiation detector. Thus, the communication between the two galvanically separated portions of the optocoupler is provided by the optical link between electromagnetic radiation source and electromagnetic radiation detector. This optical path may bridge electrical paths, which are separate from each other, at the side of the electromagnetic radiation source and at the side of the electromagnetic radiation detector.

In an embodiment, the electromagnetic radiation source is configured for emitting electromagnetic radiation only at its side wall and not or not substantially at any one of its main surfaces. By triggering the emission of electromagnetic radiation to occur via a side wall of the electromagnetic radiation source only, a well-defined and directed transmission of the electromagnetic radiation may be enabled. This renders the transmission efficiency of the optocoupler high.

In an embodiment, the electromagnetic radiation detector is configured for detecting electromagnetic radiation at one of its main surfaces, in particular only at one of its main surfaces. This may be done by forming the pn-junction of a photodiode type electromagnetic radiation detector close to an upper main surface thereof. By using a large main surface of the electromagnetic radiation detector for detection purposes, a high detection efficiency may be achieved.

In an embodiment, the optocoupler comprises a control unit coupled with the electromagnetic radiation detector and configured for carrying out a control task (in particular carrying out a switching task) or for controlling (in particular switching) based on the detected electromagnetic radiation. For instance, such a control unit may be one or multiple semiconductor chips and/or any other circuitry. It is also possible that the control unit comprises software elements. The control unit may be provided with the signals detected by the electromagnetic radiation detector. The control unit may then further process such signals so as to recover an electric signal which was transmitted in the form of the electromagnetic radiation from the electromagnetic radiation source.

In an embodiment, the optocoupler comprises an optically transparent encapsulant, in particular a transparent gel, in which at least part of the electromagnetic radiation source and at least part of the electromagnetic radiation detector are embedded. Such an optically transparent encapsulant may be optically transparent in a wavelength range of the electromagnetic radiation propagating between the electromagnetic radiation source and the electromagnetic radiation detector. In this context, electrically transparent may denote a property of the encapsulant according to which the encapsulant is substantially non-absorbent for the electromagnetic radiation transmitted between electromagnetic radiation source and electromagnetic radiation detector. For instance, the encapsulant may be a transparent gel through which visible light may propagate with low loss or low damping.

In an embodiment, the optocoupler comprises 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 for reflecting at least part of (in particular for totally reflecting) electromagnetic radiation emitted by the electromagnetic radiation source. For instance, at an interior bounding surface of the housing body (which may correspond to an outer bounding surface of the encapsulant), electromagnetic radiation propagating from the electromagnetic radiation source and away from the electromagnetic radiation detector may be reflected and may thus be promoted to propagate towards the electromagnetic radiation detector. Thus, the efficiency of the optical transmission may be further improved. For instance, at least part of the housing body may be opaque to thereby disable or at least suppress undesired propagation of environmental light to the electromagnetic radiation detector.

In an embodiment, said interior reflective surface of the housing body (which may correspond to an exterior surface of the optically transparent encapsulant) is configured for reflecting and directing at least part of the electromagnetic radiation onto the electromagnetic radiation detector. In particular, a curved (for instance elliptically curved) reflective surface may be configured in a way so that it focuses electromagnetic radiation onto the light sensitive surface of the electromagnetic radiation detector. This may further improve the efficiency of the optical coupling.

In an embodiment, the electromagnetic radiation source is configured for emitting red light, in particular exclusively red light. When using an electromagnetic radiation source emitting in the range of red light (i.e. around <NUM>), relatively simple components may be used for electromagnetic radiation source and electromagnetic radiation detector and undesired losses due to scattering can be kept small.

In an embodiment, the optocoupler comprises a source carrier on which the electromagnetic radiation source is mounted. Furthermore, the optocoupler may comprise a detector carrier on which the electromagnetic radiation detector is mounted. Said carriers may be electrically conductive. For instance, said carriers may be leadframes, for instance made of copper. Alternatively, other kind of carriers may be used, for example a carrier with an electrically insulating and thermally conductive layer (for instance ceramic), covered on both opposing main surfaces thereof with a respective copper foil. For instance, a Direct Copper Bonding (DCB) substrate or a Direct Aluminium Bonding (DAB) substrate may be used. The source carrier and the detector carrier may be galvanically separated or electrically decoupled from each other. By taking this measure, a direct electric connection between electromagnetic radiation source and electromagnetic radiation detector and the assigned circuit portions may be prevented, and the bridge in between may be provided by the optical link.

In one embodiment, source carrier and detector carrier may be separate carriers. In another embodiment, source carrier and detector carrier may be different sections of a common carrier. For instance, the source carrier and the detector carrier are leadframes or are separated sections of a common leadframe. When embodied as one or two leadframes, the carriers may be provided with small effort and may simultaneously fulfil a mechanical supporting function and an electric function. In such a scenario, at least one of the carriers may transport an electric signal which is converted into an optical signal at the optical interface between electromagnetic radiation source and electromagnetic radiation detector.

In an embodiment, the source carrier and the detector carrier are plate shaped planar structures. This allows the manufacture of the optocoupler in a vertically compact way.

In an embodiment, the source carrier and the detector carrier are arranged at the same vertical level. When arranged at the same level, the electromagnetic propagation path may be rendered very short.

In an embodiment, 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. When emitting the electromagnetic beam via a side wall of the electromagnetic radiation source and detecting the electromagnetic beam at a top-side main surface of the electromagnetic radiation detector, it may be preferred, for an efficient optical link, to arrange the electromagnetic radiation detector at a lower vertical level than the electromagnetic radiation source. This may render the optical transmission even more efficient.

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. Preferably, a portion of the detector carrier may be slanted with respect to a remaining planar portion of the detector carrier as well as with respect to the source carrier. In such a configuration, the electromagnetic radiation propagating from the side wall of the electromagnetic radiation source hits the light sensitive surface of the electromagnetic radiation detector being slanted with respect to a horizontal direction with high efficiency. This renders the transmission of the optical signal even more efficient. Tilting a portion of the detector carrier may for instance be accomplished by bending a corresponding portion of a leadframe.

In an embodiment, the optocoupler comprises a deflector arranged for deflecting at least part of the emitted electromagnetic radiation onto the electromagnetic radiation detector. Such a deflector may deflect electromagnetic radiation which has propagated from the electromagnetic radiation source to the electromagnetic radiation detector without reaching the light sensitive surface of the electromagnetic radiation detector. By deflecting such light back onto the light sensitive surface of the electromagnetic radiation detector further improves the efficiency of the light transmission.

In an embodiment, the deflector is mounted on a detector carrier on which also the electromagnetic radiation detector is mounted. Thus, no additional mounting base for the deflector is necessary which renders the optocoupler compact and light in weight.

In an embodiment, the electromagnetic radiation detector is arranged between the electromagnetic radiation source and the deflector. For instance, electromagnetic radiation source, electromagnetic radiation detector and deflector may be arranged along a substantially longitudinal path so that electromagnetic radiation which has missed the detection surface of the electromagnetic radiation detector can be deflected by the deflector back onto the detecting surface.

In an embodiment, the deflector has a deflecting surface being angled with a deflection angle in a range between <NUM>° and <NUM>°, in particular about <NUM>°, with respect to incident electromagnetic radiation emitted by the electromagnetic radiation source and being deflected onto the electromagnetic radiation detector. It has turned out that, with the mentioned deflection angles, an efficient deflection of electromagnetic radiation onto the detection surface of the electromagnetic radiation detector is possible.

In an embodiment, the deflector comprises or consists of a solderable material (for instance a metallic material such as copper). In particular, the deflector may be soldered onto a detector carrier (for instance a leadframe portion made of copper) on which the electromagnetic radiation detector is mounted. Thus, the deflector can be soldered onto the detector carrier, for instance a leadframe.

In an embodiment, the optocoupler is configured as relay, in particular solid-state relay. The optocoupler may thus be integrated in a solid-state switch which allows to carry out a switching performance in an electric circuit. The switching can be carried out based on the optical signal transmitted from the electromagnetic radiation source to the electromagnetic radiation detector without galvanic coupling in between.

In an embodiment, the electromagnetic radiation source is configured for emitting at least <NUM>%, in particular at least <NUM>%, of an overall intensity of the electromagnetic radiation at its side wall within an angular range of not more than <NUM>°, in particular of not more than <NUM>°, around an axis perpendicular to the side wall. With such a configuration, it may be possible to concentrate the major part of the emitted electromagnetic radiation intensity within a narrow cone having an axis perpendicular to the (for instance vertical planar) side wall. Thus, a highly efficient transfer of electromagnetic radiation from the side-emitting electromagnetic radiation source to the electromagnetic radiation detector may be enabled.

In an embodiment, the side-emitting electromagnetic radiation source is configured for emitting substantially monochromatic electromagnetic radiation. Correspondingly, the electromagnetic radiation detector may be configured for detecting substantially only said substantially monochromatic electromagnetic radiation, i.e. being specifically sensitive to said wavelength. As a substantially monochromatic light source configured for side-emission, an appropriate laser diode may be implemented. In particular, when the side-emitting electromagnetic radiation source is configured as a laser diode, it will emit a very narrow bandwidth which is substantially monochromatic. Highly advantageously, the electromagnetic radiation detector may be matched concerning its detection sensitivity to said substantially monochromatic electromagnetic radiation emitted by the side-emitting electromagnetic radiation source. For instance, it is possible to adjust the band gap of the semiconductor material of the electromagnetic radiation detector (for instance a photodiode) so that the band gap fits to the emitted monochromatic electromagnetic radiation. By taking this measure, the signal-to-noise ratio may be reduced, the detection efficiency may be increased, and the suppression of unspecific environmental light and underground signals may be promoted. As a result, a highly efficient optocoupler is obtained.

The electromagnetic radiation detector is configured for detecting the electromagnetic radiation exclusively at an upper main surface of the electromagnetic radiation detector. In particular, the electromagnetic radiation detector may be configured as a photodiode having its pn-junction at the upper main surface. Thus, the detection efficiency is by far the largest in this upper main surface of the electromagnetic radiation detector. Hence, the mutual orientation between side-emitting electromagnetic radiation source and electromagnetic radiation detector may be adjusted so as to achieve a proper efficiency of transmitting the light and thereby the information.

As substrate or wafer forming the basis of implemented electronic chips, a semiconductor substrate, preferably a silicon substrate, may be used. Alternatively, a silicon oxide or another insulator substrate may be provided. It is also possible to implement a germanium substrate or a III-V-semiconductor material. For instance, exemplary embodiments may be implemented in GaN or SiC technology.

Furthermore, exemplary embodiments may make use of standard semiconductor processing technologies such as appropriate etching technologies (including isotropic and anisotropic etching technologies, particularly plasma etching, dry etching, wet etching), patterning technologies (which may involve lithographic masks), deposition technologies (such as chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), sputtering, etc.).

The above and other objects, features and advantages of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings, in which like parts or elements are denoted by like reference numbers.

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

The illustration in the drawing is schematically.

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.

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.

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.

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.

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.

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 <NUM>° and <NUM>°, in particular in a range between <NUM>° and <NUM>°, preferably around <NUM>°.

<FIG> shows a cross-sectional view of an optocoupler <NUM> according to an exemplary embodiment, not comprised in the scope of the appended claims. The optocoupler <NUM> functions as a solid-state relay.

The illustrated optocoupler <NUM> comprises a side-emitting electromagnetic radiation source <NUM> for emitting electromagnetic radiation <NUM> at its side wall <NUM>. The electromagnetic radiation source <NUM> 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 <NUM> may be configured for emitting electromagnetic radiation <NUM> only at its side wall <NUM> (i.e. at its vertical surface on the right-hand side according to <FIG>), and not at any one of its main surfaces (i.e. the two opposing horizontal surfaces of the electromagnetic radiation source <NUM> according to <FIG>) or its other side walls.

An electromagnetic radiation detector <NUM> may be provided in the optocoupler <NUM> for detecting emitted electromagnetic radiation <NUM> which has propagated up to a light-sensitive surface of the electromagnetic radiation detector <NUM>. The electromagnetic radiation detector <NUM> may be a photodiode with a light-sensitive upper main surface. Thus, said electromagnetic radiation detector <NUM> is configured for detecting the electromagnetic radiation <NUM> for example only at its upper main surfaces <NUM> according to <FIG>.

As shown, the side-emitting electromagnetic radiation source <NUM> and the electromagnetic radiation detector <NUM> are arranged side-by-side (rather than vertically stacked) so that the electromagnetic radiation <NUM> emitted by the electromagnetic radiation source <NUM> propagates substantially horizontally up to the electromagnetic radiation detector <NUM>.

The electromagnetic radiation source <NUM> and the electromagnetic radiation detector <NUM> 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 <NUM>.

As shown in <FIG> as well, the optocoupler <NUM> comprises a planar plate shaped metallic source carrier <NUM> on which the electromagnetic radiation source <NUM> is mounted, for instance by soldering or sintering. Moreover, a planar plate shaped metallic detector carrier <NUM> is provided on which the electromagnetic radiation detector <NUM> is mounted, for instance by soldering or sintering. By an electrically conductive connection element <NUM>, such as a bond wire or bond ribbon or alternatively a clip, an upper main surface of the electromagnetic radiation source <NUM> is electrically connected to the source carrier <NUM>. Correspondingly, an upper main surface of the electromagnetic radiation detector <NUM> is electrically connected to a control unit <NUM> (described below in further detail) by an electrically conductive connection element <NUM>, such as a bond wire or bond ribbon or alternatively a clip. For example, the source carrier <NUM> and the detector carrier <NUM> 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 <NUM> and detector carrier <NUM> may be electrically decoupled.

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

As shown as well in <FIG>, the optocoupler <NUM> comprises an optically transparent encapsulant <NUM>, such as a transparent gel, in which the electromagnetic radiation source <NUM> and the electromagnetic radiation detector <NUM> are embedded in such a way that the electromagnetic radiation propagates within the optically transparent encapsulant <NUM> with low losses.

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

The electromagnetic radiation source <NUM> 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 <NUM>, 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 <NUM> with reasonable effort.

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

As shown in <FIG> as well, the electromagnetic radiation source <NUM> may be configured for emitting a major portion of for instance at least <NUM>% of an intensity of the electromagnetic radiation <NUM> via its side wall <NUM> within a narrow angular range α of for instance <NUM>° around an axis extending horizontally according to <FIG> and perpendicular to the side wall <NUM>. 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 <NUM>, a highly efficient transfer of electromagnetic radiation <NUM> from the side-emitting electromagnetic radiation source <NUM> to the electromagnetic radiation detector <NUM> may be promoted.

<FIG> shows a cross-sectional view of an optocoupler <NUM> according to another exemplary embodiment, not comprised in the scope of the appended claims.

The embodiment of <FIG> differs from the embodiment shown in <FIG> in that, according to <FIG>, the source carrier <NUM> and the detector carrier <NUM> are arranged at the same vertical level <NUM>. Since both source carrier <NUM> and detector carrier <NUM> are at the same vertical level, they can be realized by a common patterned or structured metal plate.

According to <FIG>, one leadframe constituents the source carrier <NUM> and the detector carrier <NUM> 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> where both emitter (i.e. electromagnetic radiation source <NUM>) and detector (i.e. electromagnetic radiation detector <NUM>) 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 <NUM> in order to illuminate the front-side, i.e. light-sensitive surface <NUM>, of the electromagnetic radiation detector <NUM>.

<FIG> shows a cross-sectional view of an optocoupler <NUM> according to still another exemplary embodiment, not comprised in the scope of the appended claims.

The embodiment of <FIG> differs from the embodiment shown in <FIG> in that, according to <FIG>, the source carrier <NUM> is arranged at a higher vertical level <NUM> than the detector carrier <NUM>. As a result, the light-emitting side wall <NUM> is arranged at a higher vertical level than a facing side wall <NUM> of the electromagnetic radiation detector <NUM>.

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

<FIG> shows a cross-sectional view of an optocoupler <NUM> according to yet another exemplary embodiment.

According to <FIG>, a part of the detector carrier <NUM> is slanted (for instance by bending a metal plate) so that the electromagnetic radiation source <NUM> and the electromagnetic radiation detector <NUM> are tilted with respect to each other.

Descriptively speaking, the source-facing end section <NUM> of detector carrier <NUM> 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 <NUM>, electromagnetic radiation detector <NUM>, source carrier <NUM> and detector carrier <NUM>).

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

The optocoupler <NUM> according to <FIG> comprises a deflector <NUM> arranged for deflecting part of the emitted electromagnetic radiation <NUM> onto the electromagnetic radiation detector <NUM>, to thereby increase the portion of the emitted electromagnetic radiation <NUM> which can be detected on the light-sensitive surface <NUM> of the electromagnetic radiation detector <NUM>. As shown, the deflector <NUM> is mounted in a simple way on detector carrier <NUM> on which also the electromagnetic radiation detector <NUM> is mounted. The electromagnetic radiation detector <NUM> is thus arranged in a horizontal direction between the electromagnetic radiation source <NUM> and the deflector <NUM>. The illustrated deflector <NUM> has a deflecting surface <NUM> being angled with a deflection angle β=<NUM>° with respect to said part of the incident electromagnetic radiation <NUM> to be deflected onto the electromagnetic radiation detector <NUM>. Preferably, the deflector <NUM> may be made of a solderable material and may be soldered onto detector carrier <NUM> on which the electromagnetic radiation detector <NUM> is mounted.

Hence, <FIG> shows a reflector or deflector <NUM> on the receiving leadframe side. This configuration with laser diode may result in a highly directional illumination. <NUM>°-angled deflector <NUM> 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.

By the arrangement of the deflector <NUM> vertically protruding beyond the electromagnetic radiation detector <NUM>, horizontally propagating light originating from the side wall <NUM> of the electromagnetic radiation source <NUM> and propagating horizontally may be deflected efficiently onto the light sensitive upper main surface <NUM> of the electromagnetic radiation detector <NUM>, to thereby further improve the optical coupling efficiency.

Claim 1:
An optocoupler (<NUM>), which comprises:
• a side-emitting electromagnetic radiation source (<NUM>) for emitting electromagnetic radiation at its side wall (<NUM>); and
• a plate-shaped electromagnetic radiation detector (<NUM>) for detecting at least part of the emitted electromagnetic radiation;
• a source carrier (<NUM>) on which the electromagnetic radiation source (<NUM>) is mounted, and a detector carrier (<NUM>) on which the electromagnetic radiation detector (<NUM>) is mounted;
• wherein the electromagnetic radiation detector (<NUM>) is configured for detecting electromagnetic radiation at its upper main surface (<NUM>);
• characterised in that at least a part of at least one of the source carrier (<NUM>) and the detector carrier (<NUM>) is slanted so that the electromagnetic radiation source (<NUM>) and the electromagnetic radiation detector (<NUM>) are tilted with respect to each other.