Sensor unit and method for detecting an external object

Abstract

A sensor unit (10) for detecting an external object (E) is described, wherein the sensor unit (10) comprises: - an emitter component (1) provided for emitting primary radiation (R), - a first detector component (2A) provided for receiving deflected primary radiation (R d) and generating at least one first detector signal thereof, - a second detector component (2B), which is more distant from the emitter component (1) than the first detector component (2A) and is provided for receiving deflected primary radiation (R d) and generating at least one second detector signal thereof, wherein the first detector component (2A) and the second detector component (2B) are provided for receiving deflected primary radiation (R d) of a similar or same wavelength distribution, - an encapsulant (4), which covers the emitter component (1), the first detector component (2A) and the second detector component (2B) and has a deflection area (4A), where part of the primary radiation (R) is deflected, and - a contact area (10A), which is provided for contacting the external object (E). Moreover, a sensor unit (10) with an inverted design and a method for detecting an external object (E) are described. A refractive index of the encapsulant (4) is higher than a refractive index of the part of a living object which leads to a decrease in total internal reflection at the deflection area compared to the case where the external object is missing on the contact area. When a material object is in contact with the contact area, scattering is the dominant deflection process.

Description

[0001] Description

[0002] SENSOR UNIT AND METHOD FOR DETECTING AN EXTERNAL OBJECT

[0003] A sensor unit and method suitable for detecting an external object are specified. For example, the sensor unit is suited for detecting the presence or absence of the external object on a contact area of the sensor unit. Moreover, the sensor unit is suited for discriminating a living object or part thereof from a material object. The sensor unit may be used for wearable devices like in-ear headphones.

[0004] There are known wearable devices comprising in each case an NIR (Near InfraRed) proximity sensor in order to detect a living object or parts thereof getting into contact with the wearable device. For example, the wearable device is switched on if contact is made with the living object or parts thereof and is switched off if the contact with the living object or parts thereof is interrupted. This approach bears a high risk of false detection because the proximity sensor may deliver similar signals for living objects or parts thereof and material objects.

[0005] A more advanced concept is based on SWIR (Shortwave InfraRed) sensors, which in each case provide radiation of two or more wavelengths and utilize specific, wavelength-dependent reflectivities of the external object to discriminate, for example, a living object or parts thereof from a material object. However, this type of sensors is comparatively expensive .

[0006] One object inter alia is to specify a low-cost sensor unit with improved reliability. This object is achieved inter alia by the sensor unit according to the independent product claims .

[0007] Another obj ect inter alia is to speci fy a method of high reliability for detecting an external obj ect . This obj ect is achieved inter alia by the method according to the independent method claim .

[0008] Further embodiments and further developments of the sensor unit and the method are the subj ect-matter of the dependent claims .

[0009] According to at least one embodiment of a sensor unit for detecting an external obj ect , the sensor unit comprises an emitter component provided for emitting primary radiation . For example , the emitter component comprises or consists of a light emitting diode device , wherein the light emitting diode device emits primary radiation during operation .

[0010] According to at least one embodiment , the sensor unit comprises a first detector component provided for receiving deflected primary radiation and generating at least one first detector signal thereof . In the context of the present application, the deflected primary radiation may be understood as primary radiation emitted by the emitter component but having an altered emission direction with respect to the original emission direction due to interaction with the environment . The primary radiation may be deflected by processes like reflection, such as total internal reflection, and / or scattering .

[0011] According to at least one embodiment , the sensor unit comprises a second detector component provided for receiving deflected primary radiation and generating at least one second detector signal thereof . For example , the second detector component is more distant from the emitter component than the first detector component . The emitter component , the first detector component and the second detector component may be arranged in a common plane . A distance between the emitter component and the respective detector component can be determined parallel to the common plane .

[0012] The first detector component and the second detector component may each have a particularly high sensitivity in a spectral range of the primary radiation . Moreover, the first detector component and the second detector component may be provided for receiving deflected primary radiation of a similar or same wavelength distribution . In the context of the present application, similar wavelength distributions may denote wavelength distributions , which overlap partly with each other .

[0013] According to at least one embodiment or configuration, the first detector component and the second detector component each comprise or consist of a photodiode .

[0014] According to at least one embodiment , the sensor unit comprises an encapsulant , which has a deflection area, where part of the primary radiation is deflected . The encapsulant may cover the emitter component , the first detector component and the second detector component . Especially, interspaces between the components are filled by the encapsulant . The encapsulant may be transmissive for a main part of the primary radiation . According to at least one embodiment , the sensor unit has a contact area, which is provided for a contact with the external obj ect . For example , the contact area is arranged close to the deflection area, for example on a side of the encapsulant facing away from the components , or is formed by the deflection area .

[0015] According to at least one embodiment of a sensor unit for detecting an external obj ect , the sensor unit comprises :

[0016] - an emitter component provided for emitting primary radiation,

[0017] - a first detector component provided for receiving deflected primary radiation and generating at least one first detector signal thereof ,

[0018] - a second detector component , which is more distant from the emitter component than the first detector component and is provided for receiving deflected primary radiation and generating at least one second detector signal thereof , wherein the first detector component and the second detector component are provided for receiving deflected primary radiation of a similar or same wavelength distribution,

[0019] - an encapsulant , which covers the emitter component , the first detector component and the second detector component and has a deflection area, where part of the primary radiation is deflected, and

[0020] - a contact area, which is provided for a contact with the external obj ect .

[0021] Advantageously, the sensor unit has a higher reliability than the above-mentioned NIR proximity sensor due to the first and second detector components and is less complex and expensive than the above-mentioned SWIR sensor for only requiring primary radiation of a single wavelength or wavelength distribution .

[0022] The advantages of a higher reliability and a less complex and expensive design can be achieved, too , i f the sensor unit has an inverted design and comprises a first emitter component , a second emitter component and a detector component , wherein the first and second emitter components can replace the first and second detector components and the detector component can replace the emitter component . The first and second emitter components each may be embodied in the same way as the emitter component mentioned above and the detector component may be embodied in the same way as one of the first and second detector components mentioned above .

[0023] According to at least one embodiment of a sensor unit for detecting an external obj ect , the sensor unit comprises :

[0024] - a first emitter component provided for emitting primary radiation,

[0025] - a second emitter component provided for emitting primary radiation, wherein the first emitter component and the second emitter component are provided for emitting primary radiation of a similar or same wavelength distribution,

[0026] - a detector component provided for receiving deflected primary radiation from the first emitter component and generating at least one first detector signal thereof and provided for receiving deflected primary radiation from the second emitter component and generating at least one second detector signal thereof , wherein the second emitter component is more distant from the detector component than the first emitter component ,

[0027] - an encapsulant , which covers the detector component , the first emitter component and the second emitter component and has a deflection area, where part of the primary radiation is deflected, and

[0028] - a contact area, which is provided for a contact with the external obj ect .

[0029] The first emitter component and the second emitter component may emit primary radiation at di f ferent times so that distinctive first and second detector signals can be generated .

[0030] According to at least one embodiment or configuration, the sensor unit dispenses with an optical barrier between the emitter component and the first and second detector components or between the detector component and the first and second emitter components . The missing optical barrier leads to crosstalk between the emitter component and the first and second detector components or the first and second emitter components and the detector component .

[0031] Advantageously, the ef fect of crosstalk is utili zed within the present application for detection purposes . In contrast thereto , the above-mentioned NIR proximity sensor of known wearable devices uses an optical barrier between emitter and detector to decrease crosstalk, which however increases package complexity and costs . Compared thereto , the design of the sensor unit is characteri zed by its simplicity and low costs .

[0032] For example , the external obj ect is a part of a living obj ect or a material obj ect . Advantageously, the sensor unit is suited for discriminating a part of a living obj ect like the skin of somebody' s ear or hand from a material obj ect like a plastic or wooden obj ect . The discrimination is possible due to the di f ferent reflection and scattering properties of the di f ferent external obj ects regarding the primary radiation .

[0033] According to at least one embodiment or configuration, a refractive index of the encapsulant is higher than a refractive index of the part of the living obj ect . For example , the part of the living obj ect leads to a change , in particular to a decrease in total internal reflection at the deflection area compared to the case where the external obj ect is missing on the contact area .

[0034] According to at least one embodiment or configuration, the primary radiation is dominated by a wavelength in the infrared region, for example in the near infrared region . This spectral region is especially suitable for the detection of skin because skin has its highest reflectivity in the near infrared region . For example , the sensor unit is a near infrared proximity sensor .

[0035] Suitable materials for the emitter component ( s ) or light emitting diode device are semiconductor materials based on arsenide , phosphide or nitride compound semiconductors , for example .

[0036] Moreover, suitable materials for the detector component ( s ) or photodiode ( s ) are semiconductor materials like silicon or materials based on arsenide , phosphide or nitride compound semiconductors , for example .

[0037] According to at least one embodiment or configuration, the encapsulant contains at least one of the following materials : glass , epoxy . The components can be conformally covered by the encapsulant such that the encapsulant follows in each case a contour of the components .

[0038] According to at least one embodiment or configuration, the sensor unit comprises a carrier, for example a connection carrier like a printed circuit board . The components can be arranged on a mounting face of the carrier .

[0039] According to at least one embodiment or configuration, the sensor unit comprises a control component . During operation, the emitter and detector components can be driven by the control component . Moreover, the control component may be provided for processing and comparing the first and second detector signals and deciding whether or not there is an external obj ect on the contact area and, in the case where there is an external obj ect , whether the external obj ect is a part of a living obj ect or a material obj ect .

[0040] In accordance with at least one embodiment of a method for detecting an external obj ect , the method comprises the following steps :

[0041] - providing a sensor unit of the kind as mentioned above ,

[0042] - driving the emitter component ( s ) to emit primary radiation,

[0043] - generating at least one first detector signal of the deflected primary radiation received by the first detector component from the emitter component or received by the detector component from the first emitter component , generating at least one second detector signal of the deflected primary radiation received by the second detector component from the emitter component or received by the detector component from the second emitter component ,

[0044] - comparing the at least one first detector signal with the at least one second detector signal . According to at least one embodiment or configuration of the method or sensor unit , the primary radiation is totally reflected at the deflection area in the case where the external obj ect is missing on the contact area . In this embodiment or operating state , the at least one first detector signal can be higher than the at least one second detector signal . Especially, the components are arranged in such a way that the portion of deflected or totally reflected primary radiation is higher on the first detector component than on the second detector component in the case where the external obj ect is missing on the contact area or that the portion of deflected or totally reflected primary radiation on the detector component is higher from the first emitter component than from the second emitter component in the case where the external obj ect is missing on the contact area .

[0045] According to at least one embodiment or operating state of the method or sensor unit , the primary radiation may be partly totally reflected at the deflection area and partly scattered by the external obj ect in the case where a part of a living obj ect is in contact with the contact area . Especially, a penetration depth of the primary radiation increases i f the external obj ect is a part of a living obj ect , and the primary radiation may be scattered by di f fuse subsurface scattering in the part of the living obj ect .

[0046] While the crosstalk on the first detector component or from the first emitter component may be reduced due to the reduced total internal reflection, the crosstalk on the second detector component or from the second emitter component may be increased due to the scattering of the external obj ect . In this embodiment or operating state , it is possible that the at least one first detector signal is lower than in the case where the external obj ect is missing . Moreover, the at least one second detector signal may be higher than in the case where the external obj ect is missing . And the at least one second detector signal may be higher than the at least one first detector signal .

[0047] According to at least one embodiment or operating state of the method or sensor unit , the primary radiation is scattered by the external obj ect in the case where the material obj ect is in contact with the contact area . In this embodiment or configuration, the scattering process can be the dominant deflection process . For example , the scattering process leads to increased crosstalk on both detector components or from both emitter components . Hence , both the first detector signal and the second detector signal can be higher than in the case where the external obj ect is missing . However, it is also possible that both the first detector signal and the second detector signal are lower than in the case where the external obj ect is missing .

[0048] The sensor unit is suitable for consumer applications like headphones , mobile phones , notebooks or tablets .

[0049] Further preferred embodiments and further developments of the sensor unit and method will become apparent from the exemplary embodiments explained below in conj unction with the Figures .

[0050] Figure 1A shows a schematic side view of a part of a sensor unit according to an exemplary embodiment , Figure IB shows an image of a plan view of the sensor unit according to the exemplary embodiment , and Figure 1C shows an image of a side view of the sensor unit according to the exemplary embodiment ,

[0051] Figures 2 to 4 show di f ferent operating states of a method according to an exemplary embodiment or of the sensor unit according to the exemplary embodiment , and

[0052] Figures 5 to 8 show diagrams illustrating first and second detector signals of measurements performed with di f ferent external obj ects by means of the sensor unit according to the exemplary embodiment .

[0053] Identical , equivalent or equivalently acting elements are indicated with the same reference numerals in the figures . The figures , which are schematic illustrations , are not necessarily true to scale . Comparatively small elements and particularly layer thicknesses can rather be illustrated exaggeratedly large for the purpose of better clari fication .

[0054] In connection with Figures 1A, IB and 1C, an exemplary embodiment of a sensor unit 10 is described . The sensor unit 10 is suitable for detecting an external obj ect E or target ( see Figures 3 and 4 ) . For example , the sensor unit 10 is an

[0055] NIR proximity sensor sensing the presence or absence of the external obj ect E or target .

[0056] As shown in Figures 1A and IB, the sensor unit 10 comprises an emitter component 1 and a plurality of detector components 2 comprising a first detector component 2A and a second detector component 2B . The plurality of detector components 2 are arranged in rows and columns , forming an array of detector components 2 . Alternatively, the sensor unit 10 may have an inverted design and comprise a detector component 2 and a plurality of emitter components 1 comprising a first emitter component and a second emitter component , wherein the detector component 2 can be arranged in place of the emitter component 1 and the first and second emitter components 1 can be arranged in place of the first and second detector components 2A, 2B . The comments provided on the sensor unit 10 apply accordingly to the inverted design of the sensor unit 10 .

[0057] The emitter component 1 and the plurality of detector components 2 are arranged in a common plane , which is defined by a first lateral direction LI and a second lateral direction L2 ( see Figure IB ) , for example . In particular, the sensor unit 10 comprises a carrier 3 , for example a connection carrier like a printed circuit board, wherein the components 1 , 2 are arranged on a mounting face 3A of the carrier 3 .

[0058] The plurality of detector components 2 is laterally of fset to the emitter component 1 . In the context of the present application, " laterally of fset" may denote a displacement along at least one of the lateral directions LI , L2 . In particular, the first detector component 2A is laterally of fset to the emitter component 1 , and the second detector component 2B is laterally of fset to the emitter component 1 . Moreover, the second detector component 2B is laterally of fset to the first detector component 2A and is more distant from the emitter component 1 than the first detector component 2A. A distance between the emitter component 1 and the respective detector component 2 , 2A, 2B can be determined parallel to the common plane . For example , the emitter component 1 comprises or consists of one light emitting diode device . Moreover, the detector components 2 , in particular the first and second detector components 2A, 2B each comprise or consist of one photodiode .

[0059] The sensor unit 10 further comprises an encapsulant 4 , which covers the emitter component 1 and the plurality of detector components 2 including the first detector component 2A and the second detector component 2B .

[0060] The components 1 , 2 can be conformally covered by the encapsulant 4 such that the encapsulant 4 follows in each case a contour of the components 1 , 2 . Especially, interspaces between the components 1 , 2 are filled by the encapsulant 4 . An outer shape of the encapsulant 4 may resemble a cuboid . The encapsulant 4 comprises a deflection area 4A, which can be an outer surface of the encapsulant 4 delimiting the encapsulant 4 towards the environment on a side of the components 1 , 2 facing away from the carrier 3 . For instance , the deflection area 4A is planar .

[0061] The emitter component 1 is provided for emitting primary radiation R during operation ( see Figures 2 to 4 ) . The primary radiation R is emitted towards the deflection area 4A and passes through the encapsulant 4 . For example , the encapsulant 4 is transmissive for a main part of the primary radiation R . Suitable materials for the encapsulant 4 are glass or epoxy, for example . Part of the primary radiation R is deflected at the deflection area 4A during operation .

[0062] The first detector component 2A is provided for receiving deflected primary radiation Rdand generating at least one first detector signal S I thereof ( see Figures 5 to 8 ) during operation . The second detector component 2B is provided for receiving deflected primary radiation Rdand generating at least one second detector signal S2 thereof ( see Figures 5 to 8 ) during operation . All other detector components 2 of the plurality of detector components 2 can be operated as first detector components 2A generating at least one first detector signal S I or as second detector components 2B generating at least one second detector signal S2 .

[0063] The primary radiation R may be dominated by a wavelength in the infrared region, for example in the near infrared region . The detector components 2 including the first detector component 2A and the second detector component 2B may each have a particularly high sensitivity in a spectral range of the primary radiation R and may be sensitive for primary radiation R of a similar or same wavelength distribution .

[0064] Suitable materials for the emitter component 1 or the emitting diode device are semiconductor materials based on arsenide , phosphide or nitride compound semiconductors , for example . Moreover, suitable materials for the detector components 2 , 2A, 2B or photodiodes are semiconductor materials like silicon or materials based on arsenide , phosphide or nitride compound semiconductors , for example .

[0065] The sensor unit 10 comprises a contact area 10A, which is provided for a contact with the external obj ect E ( see Figures 3 and 4 ) . For example , the contact area 10A is identical with the deflection area 4A. However, it is also possible that the contact area 10A is di f ferent from the deflection area 4A and is arranged close to the deflection area 4A, for example on a side of the encapsulant 4 facing away from the components 1 , 2 or the carrier 3 . In connection with Figures 2 , 3 and 4 , di f ferent operating states of a method for detecting an external obj ect E or of the sensor unit 10 described in connection with Figures 1A, IB and 1C are explained .

[0066] Figure 2 shows an idle operating state , where there is no external obj ect E or target on the contact area 10A. The emitter component 1 emits primary radiation R towards the deflection area 4A of the encapsulant 4 , wherein the primary radiation R impinges on the deflection area 4A after passing through the encapsulant 4 without signi ficant deflection . The primary radiation R is deflected at the deflection area 4A by total internal reflection . This is due to the fact that the encapsulant 4 has a higher refractive index than the environment , which is ambient air, for example , and due to the fact that the primary radiation R is incident on the deflection area 4A at a suf ficiently oblique incident angle a, which is greater than the critical angle of total internal reflection .

[0067] The first detector component 2A, which is closer to the emitter component 1 than the second detector component 2B, is arranged at a position where the deflected primary radiation Rd, which is reflected at an angle p having the same value as incident angle a, impinges on the common plane or mounting face 3A. In this operating state , the at least one first detector signal S I is greater than the at least one second detector signal S2 .

[0068] The sensor unit 10 dispenses with an optical barrier between the emitter component 1 and the first and second detector components 2A, 2B so that crosstalk can happen between the emitter component 1 and the first and second detector components 2A, 2B and the deflected primary radiation Rdcan reach the first and second detector components 2A, 2B. As mentioned above, a less complex and low-cost design can be realized in this way.

[0069] Figure 3 shows an operating state where the external object E is in contact with the contact area 10A. In this operating state, the external object E is a part of a living object, which is a human being. The part of the living object may be the skin of a person's finger or ear.

[0070] In this operating state, the refractive index of the encapsulant 4 is higher than a refractive index of the external object E, wherein the refractive index of the external object E is higher than the refractive index of the environment, which is ambient air, for example. Hence, the critical angle of total internal reflection increases compared to the case where the external object E is missing and the portion of the primary radiation R that is totally reflected decreases. Hence, the at least one first detector signal SI is lower than in the case where the external object E is missing.

[0071] A portion of the primary radiation R that passes the deflection area 4A penetrates the external object E and is scattered by the external object E, especially by diffuse subsurface scattering, and is deflected towards the second detector component 2B. In this operating state, the second detector signal S2 is higher than in the case where the external object E is missing. And the second detector signal S2 is higher than the first detector signal SI. As mentioned above, the primary radiation R may be dominated by a wavelength in the infrared region, for example in the near infrared region. This spectral region is especially suitable for the detection of skin because skin has its highest reflectivity in the near infrared region.

[0072] Figure 4 shows an operating state where the external object E, which is in contact with the contact area 10A, is a material object like a plastic or wooden object, for example.

[0073] In this operating state, the dominant deflection process can be scattering by the external object E. This may result in both the at least one first detector signal SI and the at least one second detector signal S2 being higher than in the case where the external object E is missing or in the case where the external object E is a part of a living object. However, it is also possible that both the at least one first detector signal SI and the at least one second detector signal S2 are lower than in the case where the external object E is missing or in the case where the external object E is a part of a living object.

[0074] In summary, utilizing the effect of crosstalk, the sensor unit 10 is able to detect the presence or absence of the external object E and discriminate a living object or part thereof from a material object.

[0075] The sensor unit 10 can be a part of an in-ear headphone, for example, which may emerge from a sleep mode if the sensor unit 10 detects the presence of a living object or part thereof and turns to the sleep mode if the sensor unit 10 detects the presence of a material object or the absence of an external object E. The diagrams shown in Figures 5 to 8 illustrate first detector signals SI resulting for example from measurements performed by the first detector component 2A and second detector signals S2 resulting for example from measurements performed by the second detector component 2B. The detector signals SI, S2 are ADC ( analog-to-digital converter) counts taken over time, wherein the counts C are plotted on the ordinate and the time t, which is specified in seconds, is plotted on the abscissa. The measurements are performed in operating states, where an external object E is in contact with the contact area 10A of the sensor unit 10. Idle counts, that is counts resulting from measurements in the idle operating state where the external object E is missing, are subtracted from the counts C shown in the diagrams.

[0076] In Figure 5, a first measurement is shown, which is performed during a first measurement period including 0 < t < 10 s, wherein the external object E is a material object. A second measurement is performed during a second measurement period including 10 s < t < 17.5 s, wherein the external object E is the skin of a human body part like a finger or an ear.

[0077] As becomes evident from Figure 5, the first detector signals SI of the first measurement are higher than the first detector signals SI of the second measurement. And the second detector signals S2 of the first measurement are higher than the second detector signals S2 of the second measurement. Hence, the first and second detector signals SI, S2 increase if the external object E is a material object.

[0078] Moreover, it becomes evident from the second measurement that the second signals S2 increase while the first signals SI decrease compared to the idle operating state where the external object E is missing.

[0079] In Figure 6, first measurements are shown, which are performed with material objects that are plastic materials, wherein during a first measurement period including 0 < t < 7.5 s the material object is a first white ABS (acrylonitrile butadiene styrene) , during a second measurement period including 7.5 s < t d l2.5 s the material object is a second white ABS, during a third measurement period including 12.5 s < t d 17.5 s the material object is black plastic, and during a forth measurement period including 17.5 s < t < 22.5 s the material object is plexiglass.

[0080] A further measurement is shown, which is performed during a fifth measurement period including 22.5 s < t d 30 s, wherein the external object E is the skin of a human body part like a finger or an ear.

[0081] And a last measurement is shown, which is performed with a material object during a sixth measurement period including 30 s < t, wherein the material object is wood.

[0082] In accordance with Figure 5, the first detector signals SI of the measurements performed with material objects are higher than the first detector signals SI of the measurement with the skin. And in the case where the external object E is skin, the second signals S2 increase while the first signals SI decrease compared to the idle operating state where the external object E is missing.

[0083] In Figure 7, a measurement is shown, which is performed with a material object that is a water drop. As becomes evident from Figure 7, the first detector signals SI and the second detector signals S2 decrease compared to the idle operating state where the external object E is missing. Moreover, the first and second detector signals SI, S2 are lower compared to the operating state where the external object E is skin. The reason is that both total internal reflection and scattering decreases with the water drop.

[0084] In Figure 8, measurements are shown, which are performed with material objects, wherein during a first measurement period including 0 < t < 12.5 s the material object is transparent rubber, and during a second measurement period including 12.5 < t < 20 s the material object is green rubber.

[0085] As becomes evident from Figure 8, the first detector signals SI and the second detector signals S2 decrease compared to the idle operating state if the material object is transparent rubber, which behaves like the water drop discussed in connection with Figure 7, whereas the detector signals SI, S2 increase if the material object is green rubber, which behaves like the plastic materials discussed in connection with Figure 6.

[0086] In conclusion, only skin increases the signal S2 on the second detector component 2B, while the signal SI on the first detector component 2A is decreased. Hence, the sensor unit 10 has the ability to discriminate skin from material ob j ects .

[0087] The invention is not limited to these embodiments by the description based on the embodiments. Rather, the invention includes any new feature and any combination of features, which includes in particular any combination of features in the patent claims, even if this feature or this combination itself is not explicitly explained in the patent claims or embodiments . This patent application claims the priority of German patent application 102024103973.6, the disclosure content of which is hereby incorporated by reference.

[0088] References

[0089] 1 emitter component

[0090] 2 detector component

[0091] 2A first detector component

[0092] 2B second detector component

[0093] 3 carrier

[0094] 3A mounting face

[0095] 4 encapsulant

[0096] 4A deflection area

[0097] 10 sensor unit

[0098] 10A contact area a incident angle

[0099] P reflection angle

[0100] C counts

[0101] D deflection area

[0102] E external obj ect

[0103] LI first lateral direction

[0104] L2 second lateral direction

[0105] R primary radiation

[0106] Rd deflected primary radiation

[0107] 51 first detector signal

[0108] 52 second detector signal

Claims

Claims1. A sensor unit (10) for detecting an external object (E) , wherein the sensor unit (10) comprises:- an emitter component (1) provided for emitting primary radiation (R) ,- a first detector component (2A) provided for receiving deflected primary radiation (Rd) and generating at least one first detector signal (SI) thereof,- a second detector component (2B) , which is more distant from the emitter component (1) than the first detector component (2A) and is provided for receiving deflected primary radiation (Rd) and generating at least one second detector signal (S2) thereof, wherein the first detector component (2A) and the second detector component (2B) are provided for receiving deflected primary radiation (Rd) of a similar or same wavelength distribution,- an encapsulant (4) , which covers the emitter component (1) , the first detector component (2A) and the second detector component (2B) and has a deflection area (4A) , where part of the primary radiation (R) is deflected, and- a contact area (10A) , which is provided for a contact with the external object (E) .

2. A sensor unit (10) for detecting an external object (E) , wherein the sensor unit (10) comprises:- a first emitter component (1) provided for emitting primary radiation (R) ,- a second emitter component (1) provided for emitting primary radiation (R) , wherein the first emitter component(1) and the second emitter component (1) are provided for emitting primary radiation (R) of a similar or same wavelength distribution,- a detector component (2) provided for receiving deflected primary radiation (Rd) from the first emitter component (1) and generating at least one first detector signal (SI) thereof and provided for receiving deflected primary radiation (Rd) from the second emitter component (1) and generating at least one second detector signal (S2) thereof, wherein the second emitter component (1) is more distant from the detector component (2) than the first emitter component (1) ,- an encapsulant (4) , which covers the detector component (2) , the first emitter component (1) and the second emitter component (1) and has a deflection area (4A) , where part of the primary radiation (R) is deflected, and- a contact area (10A) , which is provided for a contact with the external object (E) .

3. The sensor unit (10) according to any of the preceding claims, which dispenses with an optical barrier between the emitter component (1) and the first and second detector components (2A, 2B) or between the detector component (2) and the first and second emitter components (1) .

4. The sensor unit (10) according to any of the preceding claims, wherein the external object (E) is a part of a living object or a material object.

5. The sensor unit (10) according to the preceding claim, wherein a refractive index of the encapsulant (4) is higher than a refractive index of the part of the living object.

6. The sensor unit (10) according to any of the preceding claims, wherein the contact area (10A) is arranged close to the deflection area (4A) on a side of the encapsulant (4)facing away from the components (1, 2, 2A, 2B) or is formed by the deflection area (4A) .

7. The sensor unit (10) according to any of the preceding claims, wherein the primary radiation (R) is dominated by a wavelength in the infrared region.

8. The sensor unit (10) according to any of the preceding claims, wherein the emitter component (s) (1) comprise (s) a light emitting diode device.

9. The sensor unit (10) according to any of the preceding claims, wherein the detector component (s) (2, 2A, 2B) comprise (s) a photodiode.

10. The sensor unit (10) according to any of the preceding claims, wherein the encapsulant (4) contains at least one of the following materials: glass, epoxy.

11. The sensor unit (10) according to any of the preceding claims, which is a near infrared proximity sensor.

12. A method for detecting an external object (E) , wherein the method comprises:- providing a sensor unit (10) according to any of the preceding claims,- driving the emitter component (s) (1) to emit primary radiation (R) ,- generating at least one first detector signal (SI) of the deflected primary radiation (Rd) received by the first detector component (2A) from the emitter component (1) or received by the detector component (2) from the first emitter component ( 1 ) ,- generating at least one second detector signal (S2) of the deflected primary radiation (Rd) received by the second detector component (2B) from the emitter component (1) or received by the detector component (2) from the second emitter component ( 1 ) ,- comparing the at least one first detector signal (SI) with the at least one second detector signal (S2) .

13. The method according to the preceding claim, wherein the primary radiation (R) is totally reflected at the deflection area (4A) in the case where the external object (E) is missing on the contact area (10A) , and the at least one first detector signal (SI) is higher than the at least one second detector signal (S2) .

14. The method according to claim 12 or 13, wherein the primary radiation (R) is partly totally reflected at the deflection area (4A) and partly scattered by the external object (E) in the case where a part of a living object is in contact with the contact area (10A) , and the at least one first detector signal (SI) is lower than in the case where the external object (E) is missing.

15. The method according to the preceding claim, wherein the at least one second detector signal (S2) is higher than in the case where the external object (E) is missing.

16. The method according to any of the two preceding claims, wherein the at least one second detector signal (S2) is higher than the at least one first detector signal (SI) .

17. The method according to any of claims 12 to 16, wherein the primary radiation (R) is scattered by the external object(E) in the case where a material object is in contact with the contact area (10A) , wherein both the first detector signal (SI) and the second detector signal (S2) are higher than in the case where the external object (E) is missing or both the first detector signal (SI) and the second detector signal (S2) are lower than in the case where the external object (E) is missing.

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