Headband headphone with adjustable on-ear detection, device for adjusting on-ear detection and method for adjusting on-ear detection

Abstract

Headband headphones may be provided with an on-ear detection (OED) to switch the headphone automatically on or off or into a specific mode upon detecting that the user is or is not wearing the headphone. Individual differences in the users' appearances, such as hair color and style, skin color, earrings and the shape of the auricle, often have an impact on the detection result, reducing its reliability. On-ear detection for headband headphones (100) with improved reliability allows adjusting the on-ear detection to individual characteristics of a user by setting (610) the headphone into a calibration mode, performing (620) a measurement process, wherein a light detector measures an amount of reflected light, deriving (630) a threshold value from the measured amount of reflected light, storing (640) the threshold value and terminating (650) the calibration mode. OED is improved by using the stored individual threshold value instead of a default threshold value.

Description

[0001] The invention relates to a headband headphone with adjustable on-ear detection, a device for adjusting on-ear detection for headband headphones and a method for adjusting on-ear detection for headband headphones.Background

[0002] Headband headphones may be provided with an on-ear detection (OED), which may switch the headphone automatically on or off or into a specified mode upon detecting that the user is wearing the headphone or is not wearing the headphone. On-ear detection is sometimes also referred to as on-head detection; both may be understood equivalently, namely as a detection that a user is wearing the headphone with at least one earcup being put on an ear of the user, or surrounding the ear. The OED may save power, increase the user's comfort and may help the user to hear in an optimal way sound reproduced by one or more transducers located in the earcup. E.g., OED may help to determine whether or not a headphone is worn properly, which may have an impact on passive noise reduction and automatic noise cancelling (ANC). Usually, headband headphones have two earcups that for normal operation should both be put on the user's ears. The OED usually refers to a single earcup and may be provided in one or in both earcups.

[0003] Different automatic functions of the headband headphone may be related to the OED, such as switching the headphone on or starting playback when the headphone is put on a user's ears, switching the headphone off or into pause mode when it is taken away from at least one of the ears, or switching it into a transparent mode or a power-save mode when the user has one earcup put on an ear (donned) and the other earcup taken away from the other ear (doffed). For any kind of function related to OED, it is important that the OED is highly reliable.

[0004] While OED for earphones may use various different technologies, OED for headband headphones often uses optical detection, where the headphone employs a light emitter and a light detector. The light detector may detect light that is emitted by the light emitter and reflected on the surface of the user's head (in particular the auricle or a part thereof) that is covered by the earcup. The amount of reflected light may be used to determine whether or not the respective earcup is being worn on an ear properly. However, there may be substantial differences in the light reflecting surfaces due to, e.g., individual skin color, hair color, hair style and appearance of human ears, such as the shape of the auricle. Further, the user may wear earrings, ear piercings, spectacles etc., so that a temple or another object may be in the range of the detector. All these factors have an impact on the amount of reflected light and therefore on the detection result. Moreover, similar problems may occur with other types of OED that use detectors other than optical. Thus, in some cases it is desirable for the on-ear detection to be more reliable.Summary of the Invention

[0005] It is an object of the invention to provide an improved on-ear detection for headband headphones, in particular an OED that provides an increased reliability.

[0006] This object is achieved by a method as disclosed in claim 1. In other embodiments, the invention relates to a device for adjusting an OED for a headband headphone as disclosed in claim 8, and to a corresponding headband headphone as disclosed in claim 14.

[0007] In one example, the present invention relates to a method for adjusting an on-ear detection of a headband headphone according to individual characteristics of a user. The method comprises the headphone receiving a command to enter into a calibration mode, and in response entering the calibration mode by performing a measurement process, wherein a light detector measures an amount of light emitted by a light emitter and reflected by an object, deriving a threshold value from the measured amount of reflected light, storing the threshold value and terminating the calibration mode. While the headphone is being worn, i.e. the earcup is being donned, the reflecting object is the user's head, and mainly the auricle or parts thereof. The stored threshold value can be used for optical OED with improved reliability. In particular, it is a value that is individual for the user and can be used to determine for a headband headphone whether or not it is being worn, wherein a higher detection reliability is provided than that of a conventional "one-fits-all" OED. Optionally, the measurement process may have a defined minimum temporal duration and / or result in a defined minimum number or range of measurement values.

[0008] In another example, the present invention relates to a device for adjusting an optical on-ear detection for a headband headphone. The device may be incorporated in a headband headphone and comprises a light emitting element and a light detecting element adapted for detecting light emitted by the light emitting element and reflected by a nearby object, such as a portion of a head of a user wearing the headband headphone. The device further comprises a control unit and a memory. The control unit is adapted for setting the device into a calibration mode upon having received a corresponding command, e.g. initiated by a user. The control unit is further adapted for performing a measurement process, wherein the light detecting element measures an amount of light emitted by the light emitting element and reflected by said nearby object, deriving a threshold value from the measured amount of reflected light, storing the derived threshold value in the memory and terminating the calibration mode.

[0009] In an embodiment, a plurality of values is measured and the threshold value is derived from a maximum value or a minimum value of the measured values. In an embodiment, the measurement process comprises recording the plurality of measurement values. In some embodiments, the calibration mode is terminated after a predefined number and / or range of measurement values has been measured or recorded, and / or after a predefined time. In an embodiment, the headband headphone comprises a motion detector and the measurement process is triggered or terminated according to motion information. In an embodiment, the measurement process and / or the method may be aborted if the measurement value, e.g. corresponding to an amount of reflected light, is below a minimum threshold, wherein a value below the minimum threshold may indicate that the headphone is currently not being worn by a user (e.g. if the user accidentally activates calibration mode while not wearing the headphone). In an embodiment, the device is an OED module, such as e.g. a proximity sensor. In an embodiment, the device is adapted for operating only in a nearby range, such as up to 20 mm, or not more than the thickness of an earpad mounted to the earcup, in order to exclude unwanted detection of any other objects that are farther away.

[0010] Various aspects and advantageous embodiments are provided in the following detailed description and in the claims.Brief Description of the Drawings

[0011] The present invention will be better understood from the following detailed description in conjunction with the accompanying drawings, in which like reference numerals designate like parts. The drawings show in Fig. 1a schematic drawing of a headband headphone with an OED device according to an embodiment; Fig. 2a block diagram of a device, in different embodiments; Fig. 3different potentially light-reflecting parts of an exemplary auricle; Fig. 4different exemplary threshold values; Fig. 5an exemplary view of an earcup of a headband headphone with an OED module according to an embodiment; and Fig. 6a flowchart of a method according to an embodiment. Detailed Description of the Invention

[0012] Fig. 1 shows a schematic drawing of a headband headphone 100, in an embodiment of the invention, while being worn by a user. The headphone 100 has a headband 110, an earcup 120 coupled to the headband and an optical OED module 130. A similar second earcup (not shown) may be coupled to the other end of the headband 110 and may but needs not have a separate optical OED module. The OED module 130 is located within the earcup 120, with a view on an ear and / or a portion of the head of the user wearing the headphone 100, and is usually not visible while the headphone 100 is being worn. Thus, Fig. 1 is only explanatory. The OED module 130 comprises a light emitting element 210 and a light detecting element 220 in the present embodiment, as shown in Fig. 2. For example, it may be an Infrared (IR) distance sensor or proximity sensor that is commonly used for OED. The OED module 130 is placed in the earcup 120 with the light emitting element 210 and the light detecting element 220 pointing at an outside part of the user's ear. Depending on the user's individual headphone wearing style, this will usually be at least a part of the auricle 140. For example, the light emitting and detecting elements may point to the outer edge or backside of the helix. Light emitted by the light emitting element 210 is reflected by the user's ear 140, and the reflected light is detected by the light detecting element 220. In particular, the light detecting element 220 may be a light sensing element that measures an amount of reflected light. The amount of reflected light directly depends on the distance, shape, and color of the reflecting surface, i.e. the user's auricle 140.

[0013] Fig. 2 shows, in different embodiments, block diagrams of a device 200 for adjusting an optical on-ear detection for a headband headphone, wherein the device 200 is incorporated in an optical OED module 130. Fig. 2 a) shows an example where the device 200 for OED adjustment is a separate device within the OED module 130, while in Fig. 2 b) the OED module 130 itself acts as device 200 and is configured to adjust the OED; in other words, the device 200 for adjusting the OED may be implemented using existing hardware parts of the OED module 130 and additional software instructions configuring them. The device 200 may comprise a light emitting element 210, a light detecting element 220, a control unit 230 adapted to communicate with the light emitting element 210 and the light detecting element 220, and a memory 240 adapted to communicate with the control unit 230. The control unit 230 may comprise a processor configured by software, wherein the processor may also be used for other purposes. In principle, any suitable hardware circuitry may be used to implement the control unit 230. According to the invention, the control unit 230 is adapted for setting the device 200, or the OED module 130 respectively, into a calibration mode, performing a measurement and calibration process and then terminating the calibration mode. In the calibration mode, the light detecting element 220 detects or measures an amount of reflected light emitted by the light emitting element 210. During the calibration process, the control device 230 derives a threshold value from the detected or measured amount of reflected light and stores the derived threshold value in the memory 240.

[0014] Usually, OED is performed in periodical intervals. While a user is wearing the headphone, light emitted by the light emitting element 210 is reflected at a portion of the user's head, and the amount of reflected light is detected by the light detecting element 220. If the earcup with the OED is donned properly, the light is reflected mainly by the auricle 140, while otherwise, if the earcup is doffed or is donned improperly, the light is not reflected or is reflected by other parts of the head or hair. Thus, the reflected amount of light is different. Conventionally, an OED processing element 135 compares the amount of reflected light as detected by the light detecting element 220 to a standard threshold value in order to determine whether or not the headphone is currently being worn.

[0015] However, even if the earcup is donned properly, the amount of reflected light detected by the light detecting element 220 may vary considerably, depending on the user's wearing style and appearance. As shown in Fig. 3, basically each portion of the auricle may be individually different, including helix 310 with root of helix 311 and upper crus of helix 312, scapha 313, antihelix 314 with lower crus of antihelix 315 and antihelical fold 316, tragus 317 and antitragus 318, lobule 319, ear notch 320, concha 321 and navicular fossa 322. Not only the shape, size and skin color of auricles may vary between different users, but also other objects like hair, earrings etc. may have an impact on the amount of reflected light. Conventional OED may therefore become unreliable for some users, so that they are dissatisfied with OED that is based on a default or standard threshold value.

[0016] According to the invention, the default threshold value, to which the value representing the amount of reflected light is compared, can be replaced by an individually determined threshold value, which may improve the reliability of the on-ear detection. For this purpose, a user or an automated process may initiate an OED calibration process. During the OED calibration process, the control device 230 receives from the light detecting element 220 one or more measurement values, each corresponding to an amount of light emitted by the light emitting element 210, reflected by an object (i.e., a portion of the user's head that is covered by the earcup) and detected by the light detecting element 220. The control device 230 derives an individual threshold value from the measurement value and stores the derived threshold value in the memory 240. The stored individual threshold can be used for subsequent OED. However, if the result is unsatisfying, the user may return to the default threshold or a previously selected individual threshold which may be saved in the memory 240, or repeat the OED calibration process. The selection or confirmation of the threshold and / or initialization of the OED calibration process can be performed by using a control software on a smartphone or other computer device, for example.

[0017] As usual, the light emitting element 210 may emit IR light or light of any other wavelength, and the light detecting element 220 is suitable for detecting light of the emitted wavelength. The light emission and detection may be continuous or pulsed, where a pulsed operation has the advantage that detection errors e.g. due to sunlight can be reduced.

[0018] Fig. 4 shows exemplary threshold values, where X is a measurement value corresponding to an amount of reflected light. While the headphone is not being worn (i.e. doffed), very little or no light will be reflected, so that the light detecting element 220 measures a very low value X that is below a minimum threshold 410. Thus, if the measured value is below the minimum threshold 410, the headphone is surely doffed. Consequently, the OED processing element 135 may abort a possibly launched calibration process and further initiate corresponding actions, e.g. finish or pause any current playback or shut down the headphone. While the headphone is being worn on a user's head with the earcup being properly placed (i.e. donned), a certain amount of light will be reflected, so that the light detecting element 220 measures a value that is above the minimum threshold 410 and in most cases also above a default threshold 421, as shown in Fig. 4 a). In this case, the OED processing element 135 may decide that the headphone is currently donned and may enable normal headphone operation, e.g. switch on the headphone, start or continue playback or resume a previously paused playback.

[0019] While the headphone is being worn on a user's head, but one of the earcups is doffed or not properly donned (e.g., the user shifted it behind the ear), then there is usually less light reflected for this earcup than in a case where the earcup is properly donned; the light detecting element 220 typically measures a value that is higher than the minimum threshold 410 but lower than the default threshold 421. Conventionally, the OED processing element will interpret this as a "doffed" or "temporary doffed" condition and perform corresponding actions. In some cases however, depending on the individual user's auricle, hair etc. it may also happen that the measured value is below the default threshold 421 although the earcup is properly donned. In this case, the OED processing element will detect a wrong "doffed" or wrong "temporary doffed" condition and perform the corresponding actions, which is undesired. In other cases, e.g. if the individual user's head or ear is more reflective, a value may be measured that is above the default threshold 421 although the earcup is not properly donned. In this case, the OED processing element will conventionally detect a wrong "donned" condition and perform the corresponding actions, which is also undesired.

[0020] While conventionally this OED threshold is a predefined standard or default value 421 that cannot be modified, the present invention allows its individual calibration. This may increase OED reliability and may allow, e.g., to distinguish between the earcup being properly donned on an ear and the earcup being donned at another position, not covering the ear. In this case, it is possible to perform actions, e.g. switch off an earcup that is not covering the ear in order to save power and / or in order for the user not to miss audio content. For some users, the OED threshold calibration process may result in an individual threshold 422 that is lower than the default threshold 421, but still above the minimum threshold 410, as in Fig. 4 b). The reason may be that the individual user's head reflects less light than an average user's head. As mentioned above, the amount of reflected light directly depends on the distance, shape, and color of the reflecting surface, which is mainly the individual user's auricle 140. As a result, measurement values that are below the default threshold 421, but above the individual threshold 422, will correctly be interpreted as "donned" condition, while based on only the conventional default threshold 421 they would be misinterpreted as "doffed" condition. Only those measurement values that are below the individual threshold 422 will be interpreted as "doffed" condition.

[0021] For some other users, the OED threshold calibration process may result in an individual threshold 423 that is above the default threshold 421, as in Fig. 4 c). The reason may be, e.g., that the individual user's head reflects more light than an average user's head. As a result, measurement values that are below the individual threshold 423, even if they are above the default threshold 421, will correctly be interpreted as "doffed" condition, while conventionally they would be misinterpreted as "donned" condition. Only measurement values that are above the individual threshold 423 will be interpreted as "donned" condition.

[0022] If the value is below the current individual OED threshold 422,423, the OED processing element 135 may decide that the headphone is currently not being worn (doffed) and initiate corresponding actions, e.g. pause any current playback or shut down the headphone. If the value is above the current individual OED threshold 422,423, the OED processing element 135 may decide that the headphone is currently being worn (donned) and enable normal headphone operation. Of course it may happen that the OED calibration process results in an individual threshold 422,423 that almost or exactly matches the default threshold 421.

[0023] The above-described example assumes that a higher amount of reflected light corresponds to a higher measurement value (e.g., a proportional relationship). However, it is noted that this relationship may be reversed (e.g., inverse proportional), depending on the detection technology used, so that the thresholds change accordingly.

[0024] The OED calibration process may take less than 1 second or several (e.g. 1-10) seconds. Advantageously, the user may slightly move, whirl and circle the earcup during the OED calibration process, as indicated by arrows 150a-150d in Fig. 1. This will result in the light detecting element 220 providing a plurality of different measurement values, since it will have different "views" of the user's head and auricle. The range of measurement values may be individually different and can be used for determining an individual OED threshold value. In one embodiment, a minimum value of all measured values (if above the minimum threshold 410) is chosen as OED threshold value. In one embodiment, the calibration process is not terminated unless at least a minimum number of different measurement values is obtained or a defined time (maximum duration of calibration process) has elapsed.

[0025] In one embodiment, the control device 230 and / or the OED processing element 135 may also receive motion data input from a motion sensor 250 that may be incorporated in the earcup of the headphone. Thus, it is possible to start the OED calibration process when the user starts moving the earcup, or terminate the process after a defined duration or after reception of a defined number of measurement values.

[0026] During the calibration process, the measurement values may be temporarily recorded. E.g., sensor data may be continuously written into a memory array for temporal storage. A value obtained from the stored values, such as a minimum value, a maximum value, a conditional minimum value etc. may be used as the new individual threshold for OED. The recording of measurement values may but needs not comprise storing a plurality of measurement values; in an embodiment, only the highest or the lowest measured value is stored and is replaced with a new, higher or lower value once encountered.

[0027] As mentioned above, the light detecting element 220 may be an infrared (IR) light distance sensor. Fig. 5 shows an exemplary view of an earcup 500 of a headband headphone with an OED module 530 located on the inside of a cushion 560, i.e. near the transducer 570. Thus, the OED module 530 has a view on a portion of the user's head and / or auricle when the user is wearing the headphone, and simultaneously is protected from any external light source even if the user moves the earcup while performing a calibration process. In an embodiment, the earcup 500 may further comprise a motion sensor or motion detector that may be part of the OED module 530 or may be separate from the OED module 530.

[0028] Fig. 6 shows a flow-chart of a method for adjusting an optical on-ear detection of a headband headphone, in one embodiment. The method 600 comprises steps of the headphone receiving 610 a command to enter a calibration mode, e.g. initiated by the user through a smartphone app, and in response performing 620 a measurement process, wherein a light detector 220 measures an amount of light emitted by a light emitter 210 and reflected by an object, deriving 630 a threshold value from the measured amount of reflected light as described above, and storing 640 the derived threshold value. When a defined termination condition is met, such as a minimum number of values measured or a time limit reached, the calibration mode is terminated 650.

[0029] The step of performing 620 a measurement process may comprise storing one or more measurement values. The stored measurement values may be deleted or cancelled once a threshold value has been derived thereof. In an embodiment, the process 620 may comprise measuring 622 a value and evaluating 624 a measurement termination condition. If said evaluating 624 the measurement termination condition results in the condition not being met, the process returns to measuring 622 another value. In embodiments, the step of performing 620 the measurement process can be triggered according to motion information obtained from a motion sensor, indicating that the headband headphone or earcup is being moved, and / or according to touch information obtained from a touch sensor, indicating that the earcup is being touched. For example, the measurement process may start upon the earcup being moved and / or the touch sensor being touched after entering 610 the calibration mode, instead of starting immediately after initiation through an app as in a simpler embodiment. In various exemplary embodiments, the step of deriving 630 a threshold value from the measured amount of reflected light may comprise determining a minimum value or a maximum value from a plurality of measured values, determining a conditional value (e.g. a minimum within a certain time, a minimum value while the earcup is being moved, a minimum value while the earcup is being touched and moved) or similar.

[0030] The OED may be used for various purposes, e.g. to switch off playback in a doffed earcup in order to save energy. This is particularly advantageous for wireless headphones which are operated with power from a primary or secondary (rechargeable) battery.

[0031] Although the above description concentrates on optical OED, the invention can also be applied to other types of OED that use detectors other than optical; different detector types can also be combined. In an example, the above-described measurement process is performed by a detector other than a light detector measuring a physical value that indicates if the earcup is being worn, deriving a threshold value from the measured physical value, storing the threshold value and terminating the calibration mode. The physical value may be, e.g., a capacity or an acoustic value such as an ultrasound tone, a frequency response or a bass leakage detection. For example, a capacitive detector may be used for OED, alone or in combination with an optical detector. If different detector types are combined, they use separate thresholds, and they may share the same control unit or use separate control units communicating with each other. At least one of the OED detectors uses an individually calibrated threshold, as described above. A capacitance value below or above a threshold value may be used as the "donned" condition or "doffed" condition. The threshold capacitance value may be individually calibrated as described above.

[0032] In an embodiment, the invention relates to a computer-readable data carrier having stored thereon instructions that when executed cause the computer to perform a method as described above.

[0033] It is clear that various embodiments mentioned in the description may be combined if applicable, even if such combination is not expressly mentioned.

Examples

Embodiment Construction

[0012]Fig. 1 shows a schematic drawing of a headband headphone 100, in an embodiment of the invention, while being worn by a user. The headphone 100 has a headband 110, an earcup 120 coupled to the headband and an optical OED module 130. A similar second earcup (not shown) may be coupled to the other end of the headband 110 and may but needs not have a separate optical OED module. The OED module 130 is located within the earcup 120, with a view on an ear and / or a portion of the head of the user wearing the headphone 100, and is usually not visible while the headphone 100 is being worn. Thus, Fig. 1 is only explanatory. The OED module 130 comprises a light emitting element 210 and a light detecting element 220 in the present embodiment, as shown in Fig. 2. For example, it may be an Infrared (IR) distance sensor or proximity sensor that is commonly used for OED. The OED module 130 is placed in the earcup 120 with the light emitting element 210 and the light detecting element 220 point...

[0001] The invention relates to a headband headphone with adjustable on-ear detection, a device for adjusting on-ear detection for headband headphones and a method for adjusting on-ear detection for headband headphones.Background

[0002] Headband headphones may be provided with an on-ear detection (OED), which may switch the headphone automatically on or off or into a specified mode upon detecting that the user is wearing the headphone or is not wearing the headphone. On-ear detection is sometimes also referred to as on-head detection; both may be understood equivalently, namely as a detection that a user is wearing the headphone with at least one earcup being put on an ear of the user, or surrounding the ear. The OED may save power, increase the user's comfort and may help the user to hear in an optimal way sound reproduced by one or more transducers located in the earcup. E.g., OED may help to determine whether or not a headphone is worn properly, which may have an impact on passive noise reduction and automatic noise cancelling (ANC). Usually, headband headphones have two earcups that for normal operation should both be put on the user's ears. The OED usually refers to a single earcup and may be provided in one or in both earcups.

[0003] Different automatic functions of the headband headphone may be related to the OED, such as switching the headphone on or starting playback when the headphone is put on a user's ears, switching the headphone off or into pause mode when it is taken away from at least one of the ears, or switching it into a transparent mode or a power-save mode when the user has one earcup put on an ear (donned) and the other earcup taken away from the other ear (doffed). For any kind of function related to OED, it is important that the OED is highly reliable.

[0004] While OED for earphones may use various different technologies, OED for headband headphones often uses optical detection, where the headphone employs a light emitter and a light detector. The light detector may detect light that is emitted by the light emitter and reflected on the surface of the user's head (in particular the auricle or a part thereof) that is covered by the earcup. The amount of reflected light may be used to determine whether or not the respective earcup is being worn on an ear properly. However, there may be substantial differences in the light reflecting surfaces due to, e.g., individual skin color, hair color, hair style and appearance of human ears, such as the shape of the auricle. Further, the user may wear earrings, ear piercings, spectacles etc., so that a temple or another object may be in the range of the detector. All these factors have an impact on the amount of reflected light and therefore on the detection result. Moreover, similar problems may occur with other types of OED that use detectors other than optical. Thus, in some cases it is desirable for the on-ear detection to be more reliable.Summary of the Invention

[0005] It is an object of the invention to provide an improved on-ear detection for headband headphones, in particular an OED that provides an increased reliability.

[0006] This object is achieved by a method as disclosed in claim 1. In other embodiments, the invention relates to a device for adjusting an OED for a headband headphone as disclosed in claim 8, and to a corresponding headband headphone as disclosed in claim 14.

[0007] In one example, the present invention relates to a method for adjusting an on-ear detection of a headband headphone according to individual characteristics of a user. The method comprises the headphone receiving a command to enter into a calibration mode, and in response entering the calibration mode by performing a measurement process, wherein a light detector measures an amount of light emitted by a light emitter and reflected by an object, deriving a threshold value from the measured amount of reflected light, storing the threshold value and terminating the calibration mode. While the headphone is being worn, i.e. the earcup is being donned, the reflecting object is the user's head, and mainly the auricle or parts thereof. The stored threshold value can be used for optical OED with improved reliability. In particular, it is a value that is individual for the user and can be used to determine for a headband headphone whether or not it is being worn, wherein a higher detection reliability is provided than that of a conventional "one-fits-all" OED. Optionally, the measurement process may have a defined minimum temporal duration and / or result in a defined minimum number or range of measurement values.

[0008] In another example, the present invention relates to a device for adjusting an optical on-ear detection for a headband headphone. The device may be incorporated in a headband headphone and comprises a light emitting element and a light detecting element adapted for detecting light emitted by the light emitting element and reflected by a nearby object, such as a portion of a head of a user wearing the headband headphone. The device further comprises a control unit and a memory. The control unit is adapted for setting the device into a calibration mode upon having received a corresponding command, e.g. initiated by a user. The control unit is further adapted for performing a measurement process, wherein the light detecting element measures an amount of light emitted by the light emitting element and reflected by said nearby object, deriving a threshold value from the measured amount of reflected light, storing the derived threshold value in the memory and terminating the calibration mode.

[0009] In an embodiment, a plurality of values is measured and the threshold value is derived from a maximum value or a minimum value of the measured values. In an embodiment, the measurement process comprises recording the plurality of measurement values. In some embodiments, the calibration mode is terminated after a predefined number and / or range of measurement values has been measured or recorded, and / or after a predefined time. In an embodiment, the headband headphone comprises a motion detector and the measurement process is triggered or terminated according to motion information. In an embodiment, the measurement process and / or the method may be aborted if the measurement value, e.g. corresponding to an amount of reflected light, is below a minimum threshold, wherein a value below the minimum threshold may indicate that the headphone is currently not being worn by a user (e.g. if the user accidentally activates calibration mode while not wearing the headphone). In an embodiment, the device is an OED module, such as e.g. a proximity sensor. In an embodiment, the device is adapted for operating only in a nearby range, such as up to 20 mm, or not more than the thickness of an earpad mounted to the earcup, in order to exclude unwanted detection of any other objects that are farther away.

[0010] Various aspects and advantageous embodiments are provided in the following detailed description and in the claims.Brief Description of the Drawings

[0011] The present invention will be better understood from the following detailed description in conjunction with the accompanying drawings, in which like reference numerals designate like parts. The drawings show in Fig. 1a schematic drawing of a headband headphone with an OED device according to an embodiment; Fig. 2a block diagram of a device, in different embodiments; Fig. 3different potentially light-reflecting parts of an exemplary auricle; Fig. 4different exemplary threshold values; Fig. 5an exemplary view of an earcup of a headband headphone with an OED module according to an embodiment; and Fig. 6a flowchart of a method according to an embodiment. Detailed Description of the Invention

[0012] Fig. 1 shows a schematic drawing of a headband headphone 100, in an embodiment of the invention, while being worn by a user. The headphone 100 has a headband 110, an earcup 120 coupled to the headband and an optical OED module 130. A similar second earcup (not shown) may be coupled to the other end of the headband 110 and may but needs not have a separate optical OED module. The OED module 130 is located within the earcup 120, with a view on an ear and / or a portion of the head of the user wearing the headphone 100, and is usually not visible while the headphone 100 is being worn. Thus, Fig. 1 is only explanatory. The OED module 130 comprises a light emitting element 210 and a light detecting element 220 in the present embodiment, as shown in Fig. 2. For example, it may be an Infrared (IR) distance sensor or proximity sensor that is commonly used for OED. The OED module 130 is placed in the earcup 120 with the light emitting element 210 and the light detecting element 220 pointing at an outside part of the user's ear. Depending on the user's individual headphone wearing style, this will usually be at least a part of the auricle 140. For example, the light emitting and detecting elements may point to the outer edge or backside of the helix. Light emitted by the light emitting element 210 is reflected by the user's ear 140, and the reflected light is detected by the light detecting element 220. In particular, the light detecting element 220 may be a light sensing element that measures an amount of reflected light. The amount of reflected light directly depends on the distance, shape, and color of the reflecting surface, i.e. the user's auricle 140.

[0013] Fig. 2 shows, in different embodiments, block diagrams of a device 200 for adjusting an optical on-ear detection for a headband headphone, wherein the device 200 is incorporated in an optical OED module 130. Fig. 2 a) shows an example where the device 200 for OED adjustment is a separate device within the OED module 130, while in Fig. 2 b) the OED module 130 itself acts as device 200 and is configured to adjust the OED; in other words, the device 200 for adjusting the OED may be implemented using existing hardware parts of the OED module 130 and additional software instructions configuring them. The device 200 may comprise a light emitting element 210, a light detecting element 220, a control unit 230 adapted to communicate with the light emitting element 210 and the light detecting element 220, and a memory 240 adapted to communicate with the control unit 230. The control unit 230 may comprise a processor configured by software, wherein the processor may also be used for other purposes. In principle, any suitable hardware circuitry may be used to implement the control unit 230. According to the invention, the control unit 230 is adapted for setting the device 200, or the OED module 130 respectively, into a calibration mode, performing a measurement and calibration process and then terminating the calibration mode. In the calibration mode, the light detecting element 220 detects or measures an amount of reflected light emitted by the light emitting element 210. During the calibration process, the control device 230 derives a threshold value from the detected or measured amount of reflected light and stores the derived threshold value in the memory 240.

[0014] Usually, OED is performed in periodical intervals. While a user is wearing the headphone, light emitted by the light emitting element 210 is reflected at a portion of the user's head, and the amount of reflected light is detected by the light detecting element 220. If the earcup with the OED is donned properly, the light is reflected mainly by the auricle 140, while otherwise, if the earcup is doffed or is donned improperly, the light is not reflected or is reflected by other parts of the head or hair. Thus, the reflected amount of light is different. Conventionally, an OED processing element 135 compares the amount of reflected light as detected by the light detecting element 220 to a standard threshold value in order to determine whether or not the headphone is currently being worn.

[0015] However, even if the earcup is donned properly, the amount of reflected light detected by the light detecting element 220 may vary considerably, depending on the user's wearing style and appearance. As shown in Fig. 3, basically each portion of the auricle may be individually different, including helix 310 with root of helix 311 and upper crus of helix 312, scapha 313, antihelix 314 with lower crus of antihelix 315 and antihelical fold 316, tragus 317 and antitragus 318, lobule 319, ear notch 320, concha 321 and navicular fossa 322. Not only the shape, size and skin color of auricles may vary between different users, but also other objects like hair, earrings etc. may have an impact on the amount of reflected light. Conventional OED may therefore become unreliable for some users, so that they are dissatisfied with OED that is based on a default or standard threshold value.

[0016] According to the invention, the default threshold value, to which the value representing the amount of reflected light is compared, can be replaced by an individually determined threshold value, which may improve the reliability of the on-ear detection. For this purpose, a user or an automated process may initiate an OED calibration process. During the OED calibration process, the control device 230 receives from the light detecting element 220 one or more measurement values, each corresponding to an amount of light emitted by the light emitting element 210, reflected by an object (i.e., a portion of the user's head that is covered by the earcup) and detected by the light detecting element 220. The control device 230 derives an individual threshold value from the measurement value and stores the derived threshold value in the memory 240. The stored individual threshold can be used for subsequent OED. However, if the result is unsatisfying, the user may return to the default threshold or a previously selected individual threshold which may be saved in the memory 240, or repeat the OED calibration process. The selection or confirmation of the threshold and / or initialization of the OED calibration process can be performed by using a control software on a smartphone or other computer device, for example.

[0017] As usual, the light emitting element 210 may emit IR light or light of any other wavelength, and the light detecting element 220 is suitable for detecting light of the emitted wavelength. The light emission and detection may be continuous or pulsed, where a pulsed operation has the advantage that detection errors e.g. due to sunlight can be reduced.

[0018] Fig. 4 shows exemplary threshold values, where X is a measurement value corresponding to an amount of reflected light. While the headphone is not being worn (i.e. doffed), very little or no light will be reflected, so that the light detecting element 220 measures a very low value X that is below a minimum threshold 410. Thus, if the measured value is below the minimum threshold 410, the headphone is surely doffed. Consequently, the OED processing element 135 may abort a possibly launched calibration process and further initiate corresponding actions, e.g. finish or pause any current playback or shut down the headphone. While the headphone is being worn on a user's head with the earcup being properly placed (i.e. donned), a certain amount of light will be reflected, so that the light detecting element 220 measures a value that is above the minimum threshold 410 and in most cases also above a default threshold 421, as shown in Fig. 4 a). In this case, the OED processing element 135 may decide that the headphone is currently donned and may enable normal headphone operation, e.g. switch on the headphone, start or continue playback or resume a previously paused playback.

[0019] While the headphone is being worn on a user's head, but one of the earcups is doffed or not properly donned (e.g., the user shifted it behind the ear), then there is usually less light reflected for this earcup than in a case where the earcup is properly donned; the light detecting element 220 typically measures a value that is higher than the minimum threshold 410 but lower than the default threshold 421. Conventionally, the OED processing element will interpret this as a "doffed" or "temporary doffed" condition and perform corresponding actions. In some cases however, depending on the individual user's auricle, hair etc. it may also happen that the measured value is below the default threshold 421 although the earcup is properly donned. In this case, the OED processing element will detect a wrong "doffed" or wrong "temporary doffed" condition and perform the corresponding actions, which is undesired. In other cases, e.g. if the individual user's head or ear is more reflective, a value may be measured that is above the default threshold 421 although the earcup is not properly donned. In this case, the OED processing element will conventionally detect a wrong "donned" condition and perform the corresponding actions, which is also undesired.

[0020] While conventionally this OED threshold is a predefined standard or default value 421 that cannot be modified, the present invention allows its individual calibration. This may increase OED reliability and may allow, e.g., to distinguish between the earcup being properly donned on an ear and the earcup being donned at another position, not covering the ear. In this case, it is possible to perform actions, e.g. switch off an earcup that is not covering the ear in order to save power and / or in order for the user not to miss audio content. For some users, the OED threshold calibration process may result in an individual threshold 422 that is lower than the default threshold 421, but still above the minimum threshold 410, as in Fig. 4 b). The reason may be that the individual user's head reflects less light than an average user's head. As mentioned above, the amount of reflected light directly depends on the distance, shape, and color of the reflecting surface, which is mainly the individual user's auricle 140. As a result, measurement values that are below the default threshold 421, but above the individual threshold 422, will correctly be interpreted as "donned" condition, while based on only the conventional default threshold 421 they would be misinterpreted as "doffed" condition. Only those measurement values that are below the individual threshold 422 will be interpreted as "doffed" condition.

[0021] For some other users, the OED threshold calibration process may result in an individual threshold 423 that is above the default threshold 421, as in Fig. 4 c). The reason may be, e.g., that the individual user's head reflects more light than an average user's head. As a result, measurement values that are below the individual threshold 423, even if they are above the default threshold 421, will correctly be interpreted as "doffed" condition, while conventionally they would be misinterpreted as "donned" condition. Only measurement values that are above the individual threshold 423 will be interpreted as "donned" condition.

[0022] If the value is below the current individual OED threshold 422,423, the OED processing element 135 may decide that the headphone is currently not being worn (doffed) and initiate corresponding actions, e.g. pause any current playback or shut down the headphone. If the value is above the current individual OED threshold 422,423, the OED processing element 135 may decide that the headphone is currently being worn (donned) and enable normal headphone operation. Of course it may happen that the OED calibration process results in an individual threshold 422,423 that almost or exactly matches the default threshold 421.

[0023] The above-described example assumes that a higher amount of reflected light corresponds to a higher measurement value (e.g., a proportional relationship). However, it is noted that this relationship may be reversed (e.g., inverse proportional), depending on the detection technology used, so that the thresholds change accordingly.

[0024] The OED calibration process may take less than 1 second or several (e.g. 1-10) seconds. Advantageously, the user may slightly move, whirl and circle the earcup during the OED calibration process, as indicated by arrows 150a-150d in Fig. 1. This will result in the light detecting element 220 providing a plurality of different measurement values, since it will have different "views" of the user's head and auricle. The range of measurement values may be individually different and can be used for determining an individual OED threshold value. In one embodiment, a minimum value of all measured values (if above the minimum threshold 410) is chosen as OED threshold value. In one embodiment, the calibration process is not terminated unless at least a minimum number of different measurement values is obtained or a defined time (maximum duration of calibration process) has elapsed.

[0025] In one embodiment, the control device 230 and / or the OED processing element 135 may also receive motion data input from a motion sensor 250 that may be incorporated in the earcup of the headphone. Thus, it is possible to start the OED calibration process when the user starts moving the earcup, or terminate the process after a defined duration or after reception of a defined number of measurement values.

[0026] During the calibration process, the measurement values may be temporarily recorded. E.g., sensor data may be continuously written into a memory array for temporal storage. A value obtained from the stored values, such as a minimum value, a maximum value, a conditional minimum value etc. may be used as the new individual threshold for OED. The recording of measurement values may but needs not comprise storing a plurality of measurement values; in an embodiment, only the highest or the lowest measured value is stored and is replaced with a new, higher or lower value once encountered.

[0027] As mentioned above, the light detecting element 220 may be an infrared (IR) light distance sensor. Fig. 5 shows an exemplary view of an earcup 500 of a headband headphone with an OED module 530 located on the inside of a cushion 560, i.e. near the transducer 570. Thus, the OED module 530 has a view on a portion of the user's head and / or auricle when the user is wearing the headphone, and simultaneously is protected from any external light source even if the user moves the earcup while performing a calibration process. In an embodiment, the earcup 500 may further comprise a motion sensor or motion detector that may be part of the OED module 530 or may be separate from the OED module 530.

[0028] Fig. 6 shows a flow-chart of a method for adjusting an optical on-ear detection of a headband headphone, in one embodiment. The method 600 comprises steps of the headphone receiving 610 a command to enter a calibration mode, e.g. initiated by the user through a smartphone app, and in response performing 620 a measurement process, wherein a light detector 220 measures an amount of light emitted by a light emitter 210 and reflected by an object, deriving 630 a threshold value from the measured amount of reflected light as described above, and storing 640 the derived threshold value. When a defined termination condition is met, such as a minimum number of values measured or a time limit reached, the calibration mode is terminated 650.

[0029] The step of performing 620 a measurement process may comprise storing one or more measurement values. The stored measurement values may be deleted or cancelled once a threshold value has been derived thereof. In an embodiment, the process 620 may comprise measuring 622 a value and evaluating 624 a measurement termination condition. If said evaluating 624 the measurement termination condition results in the condition not being met, the process returns to measuring 622 another value. In embodiments, the step of performing 620 the measurement process can be triggered according to motion information obtained from a motion sensor, indicating that the headband headphone or earcup is being moved, and / or according to touch information obtained from a touch sensor, indicating that the earcup is being touched. For example, the measurement process may start upon the earcup being moved and / or the touch sensor being touched after entering 610 the calibration mode, instead of starting immediately after initiation through an app as in a simpler embodiment. In various exemplary embodiments, the step of deriving 630 a threshold value from the measured amount of reflected light may comprise determining a minimum value or a maximum value from a plurality of measured values, determining a conditional value (e.g. a minimum within a certain time, a minimum value while the earcup is being moved, a minimum value while the earcup is being touched and moved) or similar.

[0030] The OED may be used for various purposes, e.g. to switch off playback in a doffed earcup in order to save energy. This is particularly advantageous for wireless headphones which are operated with power from a primary or secondary (rechargeable) battery.

[0031] Although the above description concentrates on optical OED, the invention can also be applied to other types of OED that use detectors other than optical; different detector types can also be combined. In an example, the above-described measurement process is performed by a detector other than a light detector measuring a physical value that indicates if the earcup is being worn, deriving a threshold value from the measured physical value, storing the threshold value and terminating the calibration mode. The physical value may be, e.g., a capacity or an acoustic value such as an ultrasound tone, a frequency response or a bass leakage detection. For example, a capacitive detector may be used for OED, alone or in combination with an optical detector. If different detector types are combined, they use separate thresholds, and they may share the same control unit or use separate control units communicating with each other. At least one of the OED detectors uses an individually calibrated threshold, as described above. A capacitance value below or above a threshold value may be used as the "donned" condition or "doffed" condition. The threshold capacitance value may be individually calibrated as described above.

[0032] In an embodiment, the invention relates to a computer-readable data carrier having stored thereon instructions that when executed cause the computer to perform a method as described above.

[0033] It is clear that various embodiments mentioned in the description may be combined if applicable, even if such combination is not expressly mentioned.

Examples

Embodiment Construction

[0012]Fig. 1 shows a schematic drawing of a headband headphone 100, in an embodiment of the invention, while being worn by a user. The headphone 100 has a headband 110, an earcup 120 coupled to the headband and an optical OED module 130. A similar second earcup (not shown) may be coupled to the other end of the headband 110 and may but needs not have a separate optical OED module. The OED module 130 is located within the earcup 120, with a view on an ear and / or a portion of the head of the user wearing the headphone 100, and is usually not visible while the headphone 100 is being worn. Thus, Fig. 1 is only explanatory. The OED module 130 comprises a light emitting element 210 and a light detecting element 220 in the present embodiment, as shown in Fig. 2. For example, it may be an Infrared (IR) distance sensor or proximity sensor that is commonly used for OED. The OED module 130 is placed in the earcup 120 with the light emitting element 210 and the light detecting element 220 point...

Claims

1. A method (600) for adjusting an optical on-ear detection of a headband headphone, the method comprising - the headphone receiving (610) a command to enter into a calibration mode; - in response to the command, performing (620) a measurement process, wherein a light detector measures an amount of light emitted by a light emitter and reflected by an object; - deriving (630) a threshold value from the measured amount of reflected light; - storing (640) the threshold value; and - terminating (650) the calibration mode.

2. The method according to claim 1, wherein the threshold value is derived from a maximum value or a minimum value of the measured amount of reflected light.

3. The method according to claim 1 or 2, wherein the step of performing (620) the measurement process comprises measuring (622) a plurality of measurement values, evaluating (624) a condition for terminating the measurement process and terminating the measurement process upon said condition being met, wherein the condition comprises determining that at least a predefined number of measurement values has been measured.

4. The method according to claim 1, 2 or 3, wherein the step of performing (620) the measurement process comprises measuring (622) a plurality of measurement values, evaluating (624) a condition for terminating the measurement process and terminating the measurement process upon said condition being met, wherein the condition comprises determining that at least a predefined time has elapsed since entering the calibration mode.

5. The method according to one of the claims 1 to 4, wherein the step of performing (620) the measurement process is triggered or terminated according to motion information obtained from a motion sensor comprised in an earcup of the headband headphone, indicating that the earcup is being moved.

6. The method according to one of the claims 1 to 5, wherein the step of performing (620) the measurement process is triggered or terminated according to touch information obtained from a touch sensor comprised in an earcup of the headband headphone, indicating that the earcup is being touched.

7. The method according to one of the claims 1 to 6, further comprising a step of - using the stored threshold value instead of a default threshold value during optical on-ear detection, wherein an amount of reflected light below the threshold indicates that the headphone or earcup is currently not being worn.

8. A device (200) for adjusting an optical on-ear detection for a headband headphone, the device comprising - a light emitting element (210); - a light detecting element (220) adapted for detecting light emitted by the light emitting element and reflected by a portion of a user's head while the user is wearing the headband headphone; - a control unit (230) adapted for ∘ setting the device into a calibration mode; ∘ performing (620) a measurement process, wherein the light detecting element measures an amount of said reflected light; ∘ deriving (630) a threshold value from the measured amount of reflected light; and ∘ storing (640) the derived threshold value and terminating (650) the calibration mode; - and a memory (240) for storing the derived threshold value.

9. The device according to claim 8, wherein the threshold value is derived from a maximum value or a minimum value of the measured amount of reflected light.

10. The device according to claim 8 or 9, wherein the control unit (230) is further adapted for measuring (622) a plurality of measurement values during the measurement process, evaluating (624) a condition for terminating the measurement process and terminating the measurement process upon said condition being met, wherein the condition comprises counting the measurement values and determining that at least a predefined number of measurement values has been measured.

11. The device according to one of the claims 8 to 10, wherein the control unit (230) is further adapted for measuring (622) a plurality of measurement values during the measurement process, evaluating (624) a condition for terminating the measurement process and terminating the measurement process upon said condition being met, wherein the condition comprises determining that at least a predefined time has elapsed since entering the calibration mode.

12. The device according to one of the claims 8-11, wherein the device is adapted for receiving motion data from a motion sensor comprised in the headband headphone, and wherein the measurement process is triggered or terminated responsive to the received motion data.

13. The device according to claim 12, wherein the light emitting element (210), the light detecting element (220) and the motion sensor are comprised in an earcup of the headband headphone.

14. A headband headphone comprising a device according to one of the claims 8-13, further comprising at least one on-ear detection module (130) that uses the stored threshold value for determining whether or not a user is wearing the headband headphone.

15. The headband headphone according to claim 14, further comprising at least one capacitive on-ear detection sensor, wherein the on-ear detection module (130) uses the optical on-ear detection combined with the capacitive on-ear detection sensor for determining whether or not a user is wearing the headband headphone.

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