Proximity sensitive display element

Abstract

A proximity sensitive display element (1) is provided, comprising a light guide (10), at least one light emitting element (30) and at least one infrared radiation sensor (40). The light guide (10) comprises a substrate (11) having a first main side (12) and a second main side (14) opposite to each other, the first main side (12) and the second main side (14) respectively having a first reflective layer (22) and a second reflective layer (24), the first reflective layer (22) and the second reflective layer (24) having reflective inner surfaces (222, 242) facing the interior of the light guide. At least one window (16) is defined in the first main side to allow light radiation to enter and leave the light guide. At least one light emitting element (30) is embedded in the substrate, usually at the second main side of the substrate, to generate light radiation in the light guide. At least one IR sensor (40) is arranged on the second main side of the substrate and faces the first main side through a semi-transparent patch (240) in the second reflective layer (24).

Description

Technical Field

[0001] The invention relates to a proximity sensitive display element. Background Art

[0002] WO2015049425 discloses a proximity-sensitive display element configured as a composite laminate assembly for an electronic device. The assembly provides an integrated backlight for one or more indicator shapes defined by the assembly. The assembly includes a substantially opaque cover member to shield at least a portion of the electronic device. A translucent indicator structure in the cover member defines a corresponding indicator shape to allow backlight to pass through the cover member. An optical substrate layer of optically conductive material is attached to an inner surface of the cover member, wherein one or more lighting devices are embedded in the optical substrate layer and laterally offset from the associated indicator structure. Multiple lighting devices can be connected to a circuit carried on the inner surface of the cover member.

[0003] The cited document further discloses control elements formed by capacitive buttons. These elements allow capacitive proximity sensing of a user's finger when pressed on the outer surface of the cover member, so that the user can provide input.

[0004] As can be seen in the figures, the control element formed by the capacitive button is arranged outside the transparent optical element defining the indicator window with the indicator structure. For a more intuitive control, it is desirable that the control element coincides with the indicator structure. In this way, the user can easily associate a certain control element with a certain function to be controlled. However, for known devices, this would mean that the capacitive element and / or its leads obscure the indicator structure in the indicator window. Summary of the invention

[0005] It is therefore an object to provide an improved indicator structure which makes it possible to provide control elements for determining human-machine interactions associated with an indicator window without obscuring the indicator structure in the indicator window.

[0006] Accordingly, an indicator structure as claimed in claim 1 is provided.

[0007] The measures as claimed in the claim provide an optical sensor within the light guide.

[0008] The IR sensor is arranged in front of the window and thus provides good sensitivity for human touch or approach. The sensor arranged on the second main side of the substrate does not shield the indicator structure in the indicator window of the first main side opposite to the second main side. However, in order to adjust the brightness and / or uniformity of the illuminated indicator structure, a diffuser may optionally be present in the indicator window. Since the transmission of light radiation to the light guide is limited to the window facing the IR sensor, the response is selective, that is, the infrared radiation outside the window boundary is not transmitted toward the sensor (or is insufficient in intensity). If the sensor is used for proximity sensing, the sensitivity is limited to the opening angle defined by the window and the distance between the window and the sensor. Therefore, the window has a dual purpose because it determines the light distribution that defines the icon and determines the spatial angle at which the sensor is sensitive. High sensitivity of the sensor can be achieved because the sensor is arranged in front of the window. The translucent patch in the second reflective layer (partially) hides the sensor so that the sensor is not visible through the window, and the sensor in this advantageous arrangement receives sufficient IR radiation through the translucent patch because humans approach or touch the front of the window to respond appropriately. In addition, the sensitivity of the sensor can be adjusted by choosing the properties of the translucent patch, such as the transparency of the material used, or if the patch is arranged as a grid, by the openings in the grid. Instead of responding to radiation in the mid-infrared range (M-IR) corresponding to the wavelength range of radiation emitted by the human body, one or more sensors are optionally or additionally provided that are sensitive to radiation in the near-infrared (N-IR) or visible wavelength range. These can respond to radiation reflected by a hand or an artificial pointing device towards the display element, for example originating from a dedicated radiation source.

[0009] In the context of this application, sensing proximity is considered to determine whether a pointing device (especially a user's finger) is outside or inside the proximity area of ​​the proximity sensor module. In some embodiments, the proximity sensor module can be further configured to sense whether it is touched by a pointing device near it, and if so, with which pressure.

[0010] The sensitivity of the sensor can be further limited by choosing the degree of diffusion. For example, to narrow the sensitive spatial angle, a more diffuse material can be used for the light guide.

[0011] In an embodiment, the semi-transparent patches are arranged in areas where the second reflective layer is patterned as a grid.

[0012] In an embodiment, the first reflective layer is arranged between the light guide and the opaque layer. The window is defined by a common opening in the first reflective layer and the opaque layer. For example, the opening in the first reflective layer may extend beyond the boundary defined by the window to achieve a reduction in local hot spots. It is also conceivable that the opening in the opaque layer may extend beyond the boundary defined by the window. This would mean that the layer with the reflective surface becomes visible.

[0013] The opaque layer may have one or more protrusions extending towards the first main side of the light guide.Thereby, a selective absorption is achieved which may be used to improve uniformity (by reducing local hot spots).

[0014] Other layers may also be provided. These may be transparent, but may also have non-transparent portions outside the window. For example, one or more additional layers may be provided as a barrier to moisture and other substances and / or to protect the outer surface from scratches.

[0015] The light guide may be formed from a transparent substrate such as polycarbonate (PC), PMMA, ABS, TPU, PVB...

[0016] In some embodiments the light guide may be obtained by thermoforming as described in the not yet published European application 18195779.6 from the same applicant.

[0017] In an embodiment, the at least one IR sensor is one IR sensor of a plurality of IR sensors distributed on the second main side, which IR sensor faces the first main side through a corresponding translucent patch. In this embodiment, the direction of the entity from which the IR radiation enters the display element can further be determined. In addition, this makes it possible to detect movement and its direction.

[0018] According to another aspect, a proximity sensor module is provided, which includes a proximity sensitive display element as described above. In the proximity sensor module, the IR sensor is one of a plurality of proximity sensors of different types selected from a capacitive sensor, a pressure sensor, a near infrared sensor, and a mid-infrared sensor, and the proximity sensor module further includes an output unit to generate a result proximity signal based on an input proximity signal emitted by the proximity sensor. A controller of the proximity sensor module can perform an analysis indicating the reliability and accuracy of the various sensor signals and provide a result proximity signal, such as a selected one of the sensor signals or a signal indicating a weighted sum of the distances indicated by the input sensor signals according to the indicated reliability and accuracy.

[0019] Embodiments of the proximity sensor module may include an optical radiation sensor to receive a portion of optical radiation emitted by at least one light emitting element, which is reflected by a human finger through the outer surface of the at least one window in a direction toward the optical radiation sensor. Light emitted by the at least one light emitting element through the translucent window is partially reflected back by the human finger through the window toward the optical radiation sensor. In response thereto, the optical radiation sensor generates a sensing signal representing the received optical radiation. The inventors have discovered that the sensing signal is suitable for processing by a signal processor to derive a proximity signal indicating the extent of proximity of the human finger to the outer surface of the window, and the proximity signal may further indicate whether the outer surface is touched, and if so, with which pressure.

[0020] As a first method, the signal processor estimates the proximity to be indicated by the proximity signal based on the magnitude indicated by the sensing signal. Generally, if the user's finger is closer to at least one window, more light radiation is reflected, and if the pressure with which the user touches the window increases, the amount of reflected radiation increases still further. In practice, if the proximity sensor module is used by a single user, using a signal indicating a single component in the spectral range indicating the intensity of the sensed radiation may work well.

[0021] However, if the proximity sensor module is used by different users with mutually different skin colors and / or blood circulation conditions, a more robust pressure / proximity indication can be obtained in an embodiment of the proximity sensor module, wherein the optical radiation sensor is configured to provide a sensing signal having at least a first signal component and a second signal component, which first signal component and second signal component are indicative of corresponding spectral components in the received optical radiation. The inventors have particularly noticed that components of the spectrum reflected by a human finger depend strongly on the pressure applied thereby. In an embodiment, the corresponding spectral components in the received optical radiation are a red spectral component and a green spectral component. In particular, the pressure dependencies of the measured contributions of these spectral ranges differ significantly from each other, so that more information can be obtained to distinguish between changes due to pressure and other influences.

[0022] If various types of sensors are provided, the selection or weighting may be determined, for example, based on a first estimate of the distance between the entity whose approach is to be detected and the surface of the display. Given the sensitivity ranges of the various proximity sensors, the controller may determine the reliability of the sensors in indicating the distance and determine from which of these sensors a sensor signal must be selected or which weighting should be applied.

[0023] The inventor further recognizes that in known products, visual feedback in response to user input may not be visible because the user's finger accurately covers the position where the visual feedback is given. This can be avoided by providing visual feedback at a position other than the touch position, but this may confuse the user. To this end, the present disclosure provides a further embodiment, which is provided with a touch sensor to emit a sensing signal indicating the extent to which the outer surface of at least one window is touched by a human finger. The proximity sensor module is further provided with a controller coupled to the touch sensor to receive the sensing signal. If the sensing signal indicates that the outer surface is not touched, the controller has at least a first operating mode to be adopted, and if the sensing signal indicates that the outer surface is detected to be touched by a human finger, the controller has at least a second operating mode to be adopted. The controller is coupled to at least one light-emitting element to provide a drive signal to control the controllable light source according to the operating mode, so that in the second operating mode, the light irradiated from the controllable light source can be perceived by a human finger. Thus, the user can observe visual feedback at the position covered by the finger. The operation of the light source can further depend on the expected or sensed environmental conditions. For example, for indoor applications, a lower intensity than outdoor applications is usually sufficient. Predetermined settings may be used depending on the application, or a light sensor may be provided that senses the brightness of the environment in which the application with the touch-sensitive graphical user interface is used. Controls may also be provided to control settings according to user preferences, for example the operator may select a setting with a higher light intensity in the second operating mode for better visibility to compensate for less translucent skin, or in situations where the operator's attention cannot be directed to the touch-sensitive graphical user interface.

[0024] In an embodiment, in the second operation mode, the spectrum of the light irradiated by the at least one light emitting element is dominated by radiation with a wavelength in the range of 650-800nm, and the light radiation in this range (especially the light radiation in the range of 700-780nm) is relatively well transmitted through human skin. Therefore, light with a relatively low intensity is sufficient to provide a visual response. In an embodiment of this embodiment, in the first operation mode, the contribution of at least the red component in the light irradiated by the at least one light emitting element is substantially lower than the contribution of the red component in the second operation mode. Thus, the operator can clearly see whether the controller has adopted the second operation mode or remains in the first operation mode. In the first operation mode, the controllable light source can be turned off by the drive signal. Optionally, the controllable light source can be driven at a relatively low intensity different from 0, so that the controller can easily identify the control area. It can even be considered that the controllable light source is driven at a medium intensity so that even if the controller fails to adopt the second operation mode, some light is visible through a human finger. If in the first operation mode, the contribution of at least the red component in the light irradiated by the controllable light source is substantially lower than the contribution of the red component in the second operation mode, the operator can still visually distinguish between the first operation mode and the second operation mode that are erroneously adopted. It is envisaged that the controller responds with a small delay, for example 0.5s to 1.5s, so that the operator can easily compare the relatively low radiation intensity irradiated by the finger directly after touching the control area and the relatively high radiation intensity in the second operating mode after the delay.

[0025] Alternatively or in addition, the controller can drive the light source in a modulated manner. For example, in the first operating mode, the light source can be driven in a continuous manner, and in the second operating mode, the light source can be driven in a modulated manner. In another example, in the first operating mode, the light source can be driven in a modulated manner, and in the second operating mode, the light source can be driven in a continuous manner. In both examples, the operator can clearly distinguish between the first operating mode and the second operating mode. The latter example has the additional advantage that the modulated operation of the light source in the first operating mode helps to focus the operator's attention on the fact that input can be provided by touching the control area. In a further example, in both the first operating mode and the second operating mode, the light source is modulated in a different manner (e.g., at a different frequency and / or with a different duty cycle).

[0026] In some embodiments, the touch sensor may be a pressure sensor, and the controller may be configured to issue the drive signal in a manner dependent on the pressure indicated by the pressure sensor. Thus, the operator has more control options available without requiring additional areas of a touch-sensitive graphical user interface, and feedback is provided about the effect achieved through the operation of a light source visible to a human finger.

[0027] In an embodiment of the proximity sensor module, the contribution of the red component is positively correlated with the amount of pressure applied by a human finger on the outer surface. The response of the contribution of the red component positively correlated with the amount of pressure applied by the human finger on the area is intuitively clear to the operator. For example, it may be the case that the second operating mode of the controller includes at least: if the sensing signal indicates that the amount of pressure applied by the human finger on the area is less than a predetermined threshold, then the first sub-mode is adopted, and if the sensing signal indicates that the amount of pressure applied by the human finger on the area is at least equal to the predetermined threshold, then the second sub-mode is adopted, wherein the controller is configured to issue a drive signal so that the contribution of the red component in the second sub-mode is higher than the contribution of the red component in the first sub-mode. As an example, the controller can provide a ternary response corresponding to the first operating mode (no touch detected), the first sub-mode of the second operating mode (touch detected with at most moderate pressure) and the second sub-mode of the second operating mode (touch detected with relatively high pressure). These three operating modes can be easily distinguished from each other by the brightness of the light source (low, medium and high, respectively) as visible through the human finger. In addition to the first operating sub-mode and the second operating sub-mode, the second operating mode may also include one or more further sub-modes, each corresponding to a respective range of sensed pressure. Optionally, it may be the case that the contribution of the red component is positively correlated with the amount of pressure applied by a human finger on the area, wherein the controller is configured to issue the drive signal such that the contribution of the red component in the second operating mode is a continuously increasing function of the applied pressure indicated by the sense signal.

[0028] In cases where the contribution of the red component is positively correlated with the amount of pressure applied by the human finger, the perceived response may be slightly biased because the light illuminated by the light source is better transmitted through the human finger when higher pressure is applied. Compensation for this effect may be considered. In a further embodiment, the controller is configured to issue a drive signal such that the contribution of the red component is modulated according to the amount of pressure applied by the human finger on the area. For example, in a ternary case, a touch with moderate or low pressure may be signaled with a light source that emits continuously, while a touch with relatively high pressure may be signaled with a light source that operates intermittently, such as flashing every second. As a further alternative, a continuous relationship may be provided between the sensed pressure and the modulation frequency.

[0029] Measures may be taken to avoid that light with a relatively high intensity required to penetrate human skin is directly visible. This may be achieved by the controller not adopting the second mode of operation until the control area is completely covered by a human finger. Measures to provide a delay in response to touch detection may also facilitate reducing directly visible radiation.

[0030] The amount of visible radiation can be limited by appropriately choosing the width of the illumination beam of the light source. Alternatively or additionally, the control area can be clearly delimited by a translucent window within the opaque area. The illumination area defined by the translucent window and / or by the width of the light beam of the light source can be relatively small, for example a few mm. 2 , such as a circular or square area that can be easily completely covered by a human finger.

[0031] A touch-sensitive graphical user interface may be provided with a plurality of laterally distributed control areas. Each control area may have a corresponding pair of touch sensors and associated controllable light sources. Control of the associated light sources may be provided according to the above-described embodiments. In some embodiments, the light sources may be controlled in the same manner. This is advantageous because the control areas provide a consistent visible response to the operator. In other cases, such as in professional applications, it may be advantageous to provide different response types for different control areas. For example, in one control area, the visible response may be an increased light intensity, while in another control area, the visible response may be a light intensity that fluctuates when a touch is detected. In an embodiment, a common controller may be provided that controls each controllable light source according to a sensing signal provided by its associated touch / pressure sensor. Optionally, each pair of touch sensors and their associated controllable light sources may have a dedicated controller.

[0032] According to a further aspect, a method of sensing proximity to a display element is claimed in claim 24 .

[0033] Embodiments of the method may include:

[0034] - sensing whether the outer surface of the at least one window (16) is touched by a human finger;

[0035] -Controlling at least one light-emitting element according to an operation mode selected from a first operation mode and a second operation mode, wherein the first operation mode corresponds to a sensing signal indicating that the control area is not touched, and the second operation mode corresponds to a sensing signal indicating that the control area on the touch surface is touched by a human finger, and controlling the at least one light-emitting element so that light irradiated by the at least one light-emitting element can be perceived by a human finger.

[0036] Embodiments of the method may additionally or alternatively include:

[0037] - generating a sensing signal indicative of light radiation emitted by the at least one light emitting element and reflected by the human finger through the translucent window;

[0038] - calculating from said sensed signal an indication of the pressure exerted by the human finger.

[0039] The latter embodiments may further include determining a change in the sensed signal over time. The inventors have recognized that, instead of evaluating the instantaneous signal value in isolation, more accurate proximity / pressure sensing may be achieved by determining how the sensed signal changes over time. Additionally or alternatively, further accuracy may be achieved in embodiments wherein the sensed signal includes at least a first component and a second component indicative of respective spectral components in the received optical radiation, and the method includes determining whether a relative change in the first component is equal to a relative change in the second component. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] These and other aspects are described in more detail with reference to the accompanying drawings, in which:

[0041] Figure 1 schematically shows a cross section of an embodiment of a proximity sensitive display element;

[0042] Figure 2 schematically shows a cross section of a further embodiment of a proximity-sensitive display element;

[0043] Figure 2A Shown according to Figure 2 A rear view of the further embodiment of II;

[0044] Figure 3 shows a portion of a second reflective layer in an embodiment of a proximity sensitive display element;

[0045] Figure 4 schematically shows a cross section of a yet further embodiment of a proximity-sensitive display element;

[0046] Figure 5 schematically illustrates an embodiment of a proximity sensor module including an embodiment of a proximity sensitive display element;

[0047] Figure 6 In more detail, the formation Figure 5 an output unit of a portion of a proximity sensor module;

[0048] Figure 7 schematically illustrates the responsiveness of various sensors in the described embodiment of the proximity sensor module;

[0049] Fig. 8A , Figure 8B A further embodiment of a proximity sensor module is schematically shown, wherein: Fig. 8A shows a front view, and Figure 8B Shown according to Fig. 8A The cross section of VIIIB-VIIIB in FIG.

[0050] Fig. 9A , Fig. 9BA further embodiment of a proximity-sensitive display element is schematically shown;

[0051] Fig. 10A , Fig. 10B and Fig. 10C Aspects of methods of using the described embodiments are shown;

[0052] Fig.11 depicting a sensed signal as a function of time during said use;

[0053] Fig.11A depicts an exemplary signal processor for processing a sensed signal;

[0054] Fig.12 A still further embodiment of a proximity-sensitive display element is schematically shown;

[0055] Fig.13 shows the optical properties of human skin;

[0056] Fig.14A , Fig. 14B Possible operating modes in the method according to the still further embodiment are shown. DETAILED DESCRIPTION

[0057] Figure 1 Schematically shown is a cross section of a proximity-sensitive display element 1. The proximity-sensitive display element 1 comprises a light guide 10, at least one light emitting element 30 and at least one infrared radiation sensor 40, also indicated as IR sensor in the following.

[0058] like Figure 1 As shown, the light guide 10 includes a substrate 11 having a first main side 12 and a second main side 14 opposite thereto. The first main side 12 has a first reflective layer 22, and the second main side 14 has a second reflective layer 24. The first reflective layer 22 and the second reflective layer 24 each have a reflective inner surface 222, 242 facing the interior of the light guide. In the embodiment shown, the reflective layer 24 is used as a substrate that can carry additional components such as an IR sensor. In other embodiments, the reflective layer can be arranged on a separate substrate on the side opposite to the reflective inner surface 242. At least one window 16 is defined at the first main side 12 to allow light radiation to enter and leave the light guide. At least one light emitting element 30 (e.g., an LED) is embedded in the substrate 11 at the second main side 14 of the substrate 11 to generate light radiation in the light guide. In this example, the at least one light emitting element 30 is one of a pair of light emitting elements 30. Optionally, a different number of light emitting elements 30 can be provided. At least one IR sensor 40 is arranged at the second main side 14 of the substrate 11. At least one IR sensor faces the first main side 12 through a semi-transparent patch 240 in the second reflective layer 24 .

[0059] In an embodiment, the substrate 11 may be provided, for example, by a thermoplastic material such as PC, PMMA, TPU, PVB or another thermoplastic resin.

[0060] In an embodiment, the surface area of ​​the display element 1 may be, for example, of the order of a few centimeters by a few centimeters (eg 2 cm x 2 cm).The lateral dimensions of the at least one IR sensor may be of the order of a few millimeters (eg 2 mm x 2 mm).

[0061] Figure 2 An embodiment of a proximity-sensitive display element 1 is shown. The proximity-sensitive display element 1 shown therein comprises a sensor array having a plurality of IR sensors distributed on a second main side 14, the plurality of IR sensors facing the first main side 12 through corresponding translucent patches. At least one IR sensor (40) is one of the IR sensors. For example, if the surface area is relatively small, the sensor array with IR sensors can be integrated in a single component, or if the surface area is larger, the sensor array with IR sensors can be arranged as separate components, each separate component having a single IR sensor or having a subset of the array. The IR sensors can be individually addressable to read sensing values ​​from each of them. For example, in the case corresponding to Figure 2 View II Figure 2A In the illustrated embodiment, the designated at least one IR sensor 40 is addressed by a row address unit 51 with an index of 3 and by a column address unit 52 with an index of 4. The controller 50 is arranged to interface with an external signal processing device (not shown) and controls the row address unit 51 and the column address unit 52. This makes it possible to detect the direction of an entity E (e.g., a user's finger) approaching the display, and facilitates better differentiation of user input from IR radiation received from other sources. For example, knowing that the entity E is a driver with a predetermined position to the display screen, it can be assumed that the driver input is from a specific direction, and other detection signals are from other sources, such as due to solar radiation.

[0062] Figure 3 A portion of the second reflective layer 24 in an embodiment of a proximity sensitive display element is shown. The portion is shown from the side of a reflective inner surface 242 of the second reflective layer 24. A semi-transparent patch 240 (outline shown in dashed lines) for an IR sensor 40 is provided in an area where the second reflective layer 242 is patterned as a grid.

[0063] Figure 4 An embodiment of a proximity sensitive display element is shown, wherein a first reflective layer 22 is arranged between the light guide 10 and an opaque layer 26. The opaque layer 26 may have a pattern of icons to be displayed to the viewer. Figure 4In the embodiment shown, the opaque layer 26 has one or more protrusions 262 extending towards the first main side 12 of the light guide. In this way, the intensity distribution visible at the first main side 12 can be controlled. Figure 4 In the illustrated embodiment, the first reflective layer 22 is coupled to the end portion 23, for example, a polymer such as polycarbonate, and its width may range from a few hundred (eg, 250) microns to a few millimeters (eg, 2 mm or 3 mm).

[0064] The wavelength range of the at least one IR sensor 40 can be selected according to the situation in which the display element is used. In the case of use in a relatively low temperature environment, the at least one IR sensor can be set as an M-IR sensor. In this case, the sensor 40 can detect infrared radiation in the wavelength range of the human body. In the case where a heat source may be present, such as in a car exposed to sunlight, the object will usually radiate in the same range and cause a false positive. In this case, a near infrared N-IR sensor or even a sensor for detecting in the visible light range can be selected as the at least one IR sensor 40. Such a sensor can be used in conjunction with a suitable radiation source (60, Figure 1 The radiation source is arranged in such a way that the radiation it emits can be reflected by the entity to be detected towards the sensor 40, but cannot directly reach the sensor.

[0065] like Figure 5 The proximity sensor module 2 shown may include, for example, Figures 1 to 4 The proximity sensitive display element 1 of one embodiment of the embodiment shown. Figure 5 In the embodiment of the proximity sensor module 2 shown, the IR sensor 40 (here, an M-IR sensor) is one of a plurality of proximity sensors of different types. In the embodiment shown, the proximity sensor module 2 further includes an N-IR sensor 41, a capacitive sensor 42, and a pressure sensor 43. The proximity sensor module 2 further includes an output unit 7 to generate an output signal based on the input signal S emitted by the proximity sensors 40, 41, 42, 43. 40 , S 41 , S 42 , S 43 To generate the resulting proximity signal S prox The pressure sensor may be arranged in the form of a ring around the window 16 .

[0066] Figure 6 An embodiment of the output unit 7 is shown in more detail. The output unit 7 comprises for each of the sensors 40, 41, 42, 43 a respective pre-processing unit 70, 71, 72, 73 which provides a normalized output signal S in response to an input signal received from the sensor. 70, S 71 , S 72 , S 73 . In the sense that the same signal values of the signal output signals S 70 , S 71 , S 72 , S 73 represent the same distance from the entity E to the surface of the display 1, the output signals are normalized. The controller 75 receives the (normalized) output signals S 70 , S 71 , S 72 , S 73 , determines which of these signals provides the most reliable distance indication, and provides a selection signal Sel that causes the selection element 76 to select the signal determined to be the most reliable. The controller can, for example, determine a plurality of normalized signals S 70 , S 71 , S 72 , S 73 indicate that the distance between the entity and the surface of the display is within a specific range, and selects one of the normalized signals corresponding to the detector that typically has the best performance within that range. If the selection is made from the sensors in a fixed order (e.g., the order of the pressure sensor, the capacitance sensor, the NIR sensor, and the MIR sensor), the normalization for determining the selection can be avoided. In other words, if one of these sensors is currently selected to determine the distance, and the detected distance detected by the currently selected sensor is at the lower / higher boundary of its assigned detection range, then the sensor assigned to the detection range with the corresponding higher / lower boundary is selected. Optionally or additionally, it can make the selection based on a reliability indicator provided by the detector or its pre-processor. Further, it can be envisaged that the output unit 7 has a weighted adder instead of the selection element 76, which calculates the weighted sum of the normalized signal values, where the weights assigned to the signal values are positively correlated (e.g., proportional) with their reliability, and the weights add up to 1.

[0067] Figure 7 schematically shows the responsiveness of the sensors 40 to 43 according to the distance d. The M-IR sensor 40 is particularly suitable for a relatively large range (d > d 01 ), for example from a few decimeters and higher to several meters, the N-IR sensor 41 is suitable for a medium range (d 12 < d ≤ d 01 ), for example from a few centimeters to a few decimeters, the capacitance sensor 42 is suitable for a short range on the order of a few centimeters (d 23 (= 0) < d ≤ d12), and the pressure sensor 43 is suitable for a negative range (pressed in). The controller 75 can estimate from the normalized output signals S 70 , S 71, S 72 , S 73 The distance d est , and subsequently causes the selection element 76 to select the normalized output signal associated with the sensor having a detection range that includes the estimated distance.

[0068] Fig. 8A , Figure 8B A further embodiment of a proximity sensor module is schematically shown, wherein: Fig. 8A shows a front view, and Figure 8B Shown according to Fig. 8A VIIIB-VIIIB cross section in FIG. In this embodiment, windows 16A, 16R and 16B are defined at the first main side 12 of the light guide. Windows 16A, 16R and 16B are formed as icons. Icon 16R represents an arrow. The proximity sensor module has a first IR sensor element 40 and a second IR sensor element 41. The controller 7 can analyze its signal to detect the following situations.

[0069] A: Receiving a relatively strong stationary input signal S from sensor 40 40 . This may indicate selection of the option corresponding to icon A.

[0070] B: Receiving a relatively strong stationary input signal S from sensor 41 41 . This may indicate selection of the option corresponding to icon B.

[0071] C: Receive a reduced input signal S from sensor 40 40 , and receives an input signal S of increasing strength from the sensor 41 41 This may indicate selection of the option corresponding to icon R. The controller's response may be directionally sensitive in that it recognizes only this temporal dependency as an indication that the user has selected option C, while ignoring input signals S in the opposite sense. 40 , S 41 The time dependence of .

[0072] Fig. 9A , Fig. 9B A further embodiment of a proximity sensor module for a proximity sensitive display element is schematically shown. In this embodiment, the proximity sensor module comprises an optical radiation sensor 44. A portion of the optical radiation from the light emitting element 30 transmitted through the window 16 may be reflected from the surface of a human finger F at or near the outer surface 161 of the window and transmitted back via the window 16 towards the optical radiation sensor 44. The optical radiation sensor 44 is configured to generate a sense signal I indicative of the received optical radiation in response thereto. senseThe signal processor 7 coupled to the optical radiation sensor is configured to receive the sensing signal and, in response thereto, generate a proximity signal I indicating the extent to which the human finger is close to the outer surface 161. prox . Approach signal I prox It may further indicate whether outer surface 161 was touched, and if so, with what pressure.

[0073] An embodiment of the device was prepared using a white light emitting LED as the light emitting element 30 and an APDS-9960 sensor as the optical radiation sensor 44 . Fig. 10A , Fig. 10B and Fig. 10C The pictures are taken from a position relative to the touch surface 16s with low finger pressure, moderate finger pressure and strong finger pressure, respectively.

[0074] Fig.11 Sensed signals obtained from the optical radiation sensor 44 are depicted as a function of time. The sensed signals R, G, B indicating a red component signal, a green component signal, and a blue component signal are expressed as percentages of their nominal values.

[0075] In the time interval from t=0 to t=t1 (+ / −3 s), the human finger is outside the detection range and the signals R, G, B assume an idle level of about 5%, probably by internal reflections from the inner and outer surfaces of the window 16 .

[0076] In the time interval from t1 to t2 (+ / - 4 s), a finger approaches the outer surface 161 of the window 16, which results in a common increase in all signal levels. Fig. 10A The situation at time point t2 is shown.

[0077] Then, during the time interval t2 to t3 (8 s), the pressure increases from Fig. 10A The shown value is essentially 0 via the intermediate pressure ( Fig. 10B ) increases to Fig. 10C High pressure shown. Fig. 10A Compared with the state, the relative contribution of the R component is higher than the relative contributions of the other components G and B, and is independent of the applied pressure P.

[0078] That is, if P>0, then R>G>B.

[0079] However, if the pressure increases further, the ratios R / G and B also decrease to a lesser extent. Therefore, the ratios can be used as a further indication of the pressure. For example, in particular in the time intervals t4 to t5 (12s to 15s) and t6 to t7 (22s to 25s), the applied pressure is substantially higher than in the time intervals t5 to t6 (15s to 22s) and t7 to t8 (22s to 37s). Fig.11It can be seen that during application of lower pressure, the R / G ratio is about 1.6, and during application of higher pressure, the ratio drops to about 1.3 to 1.4.

[0080] exist Fig.11 It can be further observed in that all signals R, G, B show a modulation corresponding to the heartbeat during the time intervals (t3, t4; t5, t6; t7, t8). Additionally, this phenomenon can be detected as an indication of the applied pressure.

[0081] Note that the proximity sensor module can also be used as a separate module in other applications besides display elements. For example, it can be used to provide audio feedback indicating proximity / pressure detection or in an arrangement that does not provide feedback other than the effect of the touch input on the controlled device. For example, the proximity sensor module can be used to control a lighting device, and the user observes the changing lighting pattern resulting from the touch input. In an embodiment, Fig. 9A , Fig. 9B The proximity sensor module can be used, for example, to Figure 6 , Figure 7 The described approach is used in combination with other sensors such as infrared detectors. Thus, very high accuracy can be achieved, because the signal processor 7 selects the most reliable sensing signal as the output signal, or constructs the output signal from the input sensing signals by appropriately weighting the input signals according to their reliability and accuracy. Optionally, it is possible to use autonomous Fig. 9A , Fig. 9B Pressure sensor module.

[0082] Fig.11A The method for processing the sensing signal I from the optical radiation sensor 44 is shown. sense In the illustrated embodiment, the optical radiation sensor 44 is configured to provide a signal having at least a first signal component and a second signal component I sR ,I sG ,I sB The sensing signal I sense , the first signal component and the second signal component I sR ,I sG ,I sB Indicates the corresponding spectral components R, G, B in the received optical radiation. Fig.11A In the embodiment shown, the signal processor 7 comprises a demultiplexing component 703 to demultiplex the components I sR ,I sG ,I sB With the sensing signal I sense Isolation. Alternatively, the optical radiation sensor 44 may have separate outputs for providing these components.

[0083] Fig.11A The signal processor 7 has a function of providing a proximity signal I prox The output of the proximity signal I prox Indicates the degree of proximity of a human finger to the outer surface 161 of the window 16, for example, indicates the distance to the surface. The signal processor 7 may further have a separate output for providing a binary signal T / -T to indicate whether the outer surface 161 is touched. Further, the signal processor 7 may have a function of providing a signal I press If the outer surface 161 is touched, the signal will indicate the pressure at which the touch occurred. prox All of this information can be provided. For example, signal I prox may have a polarity indicating whether the surface is touched, and for one polarity, the signal I prox The magnitude of the signal I can indicate the distance to the surface, while for the other polarity, the signal I prox The size of may indicate the pressure applied to the surface. In the illustrated embodiment, the signal processor 7 has various proximity estimation components 710, 720, 730, 740, 750, each of which generates an appropriate proximity indication signal I based on various signal characteristics. prox1 ,I prox2 ,I prox3 ,I prox4 ,I prox5 Each of these proximity indication signals provides information about one or more of the distance between the finger and the surface and the pressure applied to the surface.

[0084] The first proximity estimation component 710 is used to provide an output signal I indicating an estimated proximity (or pressure) according to the magnitude indicated by the sensing signal. prox1 In this case, the magnitude of the sensed signal for this purpose is the signal I indicative of the red component R sR However, other signals I sB ,I sG Optional one or a combination of may be used for this purpose. It has been found that, in the case where the surface is not touched, the magnitude is substantially a monotonically decreasing function of the distance, whereas in the case where the surface is touched, the magnitude is substantially a monotonically increasing function of the pressure.

[0085] The second proximity estimation component 720 and the third proximity estimation component 730 are used to provide an indication of the component I of the sensing signal. sG ,I sB Relative to the other component I of the sensing signal sR The size of the output signal is close to I prox2 ,I prox3 The proximity estimation component 720 is based on the signal component I sG ,I sBThe magnitude ratio of the indicated output signal I prox2 , and the proximity estimation component 720 is based on the signal component I sG ,I sB The magnitude ratio of the indicated output signal I prox3 . Signal I prox2 ,I prox3 It is particularly indicative of proximity in terms of touch pressure, and less indicative of proximity in terms of distance.

[0086] The fourth proximity estimation component 740 is used to provide an output signal I indicating an estimated proximity magnitude according to a temporal change in the magnitude of the sensing signal. prox4 The magnitude of the sensing signal is determined by the signal I av The average value of the indication, as calculated by the average value calculation component 707 based on the signal. Optionally, the average value calculation component 707 can use the input signal component I sR ,I sG ,I sB Two of the two, or the fourth proximity estimation component 740 can use the input signal component I sR ,I sG ,I sB The proximity estimation component 740 estimates the proximity of its output signal I based on the change of its input signal rather than its absolute value. prox4 In this way, the indication is independent of the sensing signal I sense Certain deviations in the φ, for example due to skin color, which may be affected by blood pressure and ambient temperature, for example.

[0087] The fifth proximity estimation component 750 is used to provide an output signal I indicating an estimated proximity indicated by the amplitude of the AC component in the frequency range of 50-220 Hz. prox5 Similar to component 740, component 750 also uses the signal I av The average value of the indication, as calculated by the average value calculation component 707 based on the signal. Optionally, the average value calculation component 707 can use the input signal component I sR ,I sG ,I sB Two of the two, or the fifth proximity estimation component 750 can use the input signal component I sR ,I sG ,I sB It has been found that the signal component I sR ,I sG ,I sBThe intensity R, G, B of the indication is modulated at a frequency corresponding to the user's heartbeat, and the amplitude is strongly related to the pressure applied to the surface when the surface is touched by the user's finger. In particular, it is found that the detected amplitude is essentially a monotonically decreasing function of the applied pressure. If the finger does not touch the surface, the heartbeat cannot be detected (essentially).

[0088] As will become apparent from the above, the various proximity indication signals I prox1 ,I prox2 ,I prox3 ,I prox4 ,I prox5 They have different scopes of application as summarized in the table below.

[0089] Signal scope <![CDATA[I prox1 ]]> Distance and pressure <![CDATA[I prox2 ]]> pressure <![CDATA[I prox3 ]]> pressure <![CDATA[I prox4 ]]> Distance and pressure <![CDATA[I prox5 ]]> pressure

[0090] like Fig.11A The signal processor shown further comprises a combining component 705, which combines the output signals I from the proximity estimation components 710, 720, 730, 740, 750 as described above. prox1 ,I prox2 ,I prox3 ,I prox4 ,I prox5 To calculate the output signal I indicating the estimated proximity prox In the illustrated embodiment, the signal I prox The output signal I prox1 ,I prox2 ,I prox3 ,I prox4 ,I prox5 =A weighted average of the proximity (distance / pressure) indicated by each of the signals I, depending on an estimate of its accuracy. In an embodiment, the weighting may be binary, so that the signal I is selected prox1 ,I prox2 ,I prox3 ,I prox4 ,I prox5 One of the two is used as the output signal I prox For example, Figure 6 As shown, the combined component may further use one or more (normalized) output signals S from one or more other sensors 40, 41, 42, 43. 70 , S 71 , S 72 , S 73 For example, the capacitive sensor 42 may be disposed near the window 16 for this purpose, or even within the area defined by the window, as long as a semi-transparent material (eg, a transparent conductive oxide such as ITO) is used for the capacitive sensor 42 .

[0091] Fig.12 A further embodiment of a proximity-sensitive display element is schematically shown. In the embodiment shown therein, a touch sensor 45 is provided, for example Figure 6 One of the sensors 40, 41, 42, 43 or Fig. 9A , Fig. 9B A sensor or a combination thereof to generate a sensing signal I indicating the extent to which the outer surface 161 of the window 16 is touched by a human finger sense In addition, the controller 8 is coupled to the touch sensor 45 to receive the sensing signal I sense .like Fig.14A and Fig. 14B As shown, the controller has at least a first potential operation mode M1 and a second potential operation mode M2. The controller 8 is configured to adopt the first operation mode M1 if the sensing signal indicates that the outer surface is not touched, and is configured to adopt the second operation mode M2 ​​if the sensing signal indicates that the outer surface 161 is detected to be touched by a human finger. The controller 8 is coupled to the light emitting element 30 to provide a driving signal I drive The controllable light source can be controlled according to the operating mode so that in the second operating mode, the light irradiated from the controllable light source can be perceived by a human finger. Thus, visual feedback can be provided at the position where the user's finger covers the window. In an embodiment, in the second operating mode, the spectrum of light emitted by the light emitting element 30 is controlled by radiation with a wavelength in the range of 650-800nm. Fig.13 As schematically shown, human skin has a relatively high translucency in this spectral range (especially in the range of 700-780nm), and the radiation can be well perceived by the user. Therefore, a relatively moderate intensity is sufficient. In the first operating mode M1, the light radiation does not have to be visible. Therefore, in the first operating mode M1, the contribution of at least the red component in the light irradiated by the light emitting element 30 can be substantially lower than the contribution of the red component in the second operating mode M2. Therefore, the detection of touch can be made visible, because in the second operating mode, the light irradiated from the controllable light source is only perceptible by a human finger. Optionally, the controller 8 can be configured to issue a drive signal I drive , so that the contribution of at least the red component in the emitted light is modulated depending on the operating mode of the controller.

[0092] The touch sensor 45 may be configured as a pressure sensor, for example, Fig. 9A , Fig. 9B The pressure sensor described above, and the controller 8 may be configured to issue the drive signal I in a manner dependent on the pressure indicated by the pressure sensor. drive .exist Fig. 14BIn the illustrated embodiment, it is the case that the second operating mode M2 ​​of the controller 8 includes at least: if the sensing signal indicates that the amount of pressure applied by the human finger on the area is less than a predetermined threshold, the first sub-mode M21 is adopted, and if the sensing signal indicates that the amount of pressure applied by the human finger on the area is at least equal to the predetermined threshold, the second sub-mode M22 is adopted, wherein the controller is configured to issue a drive signal so that the contribution of the red component in the second sub-mode is higher than the contribution of the red component in the first sub-mode.

[0093] Alternatively, the contribution of the red component may be positively correlated with the amount of pressure applied by the human finger, since the controller is configured to issue a drive signal I drive , so that the contribution of the red component in the second operation mode M2 ​​is composed of the sensing signal I sense A continuously increasing function of the applied pressure indicated.

[0094] The controller 8 may be configured to issue a drive signal I drive , so that the contribution of the red component is modulated depending on the amount of pressure applied by a human finger on region 161.

[0095] In an embodiment, the controller does not adopt the second operating mode until the control area 161 is completely covered by a human finger. Thus, partial desensitization of the user's eyes due to stray radiation before the area is covered is avoided. Thus, the light radiation transmitted through the human finger can be more easily perceived. As an additional measure, the state transition to the second operating mode can have a delay of, for example, 0.2s to 0.7s.

[0096] In an embodiment, the control area 16s is one of a plurality of laterally distributed control areas on the touch surface, and each of the plurality of laterally distributed control areas may have a corresponding pair of touch sensors and an associated controllable light source.

[0097] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single component or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. A proximity sensor module, comprising: An optical radiation sensor (44) is provided to receive a portion of optical radiation emitted by at least one light emitting element (30) and reflected by a human finger through a semi-transparent window via an outer surface of at least one window (16) in a direction toward the optical radiation sensor (44), and to generate a sensing signal (I sense ),as well as: A signal processor (7) coupled to the optical radiation sensor to receive the sensing signal and in response thereto generate a proximity signal (I) indicative of the pressure applied by the human finger according to the magnitude indicated by the sensing signal. prox ), wherein the optical radiation sensor (44) is configured to provide a signal having at least a first signal component (I sR ) and the second signal component (I sG ) of the sensing signal (I sense ), the first signal component and the second signal component respectively indicate a red spectral component (R) and a green spectral component (G) in the received optical radiation, and wherein the signal processor (7) is configured to calculate a red signal component (I sR ) and the green signal component (I sG ) is used as the proximity signal indicating the pressure (I prox ).

2. The proximity sensor module according to claim 1, wherein: The signal processor (7) has a proximity estimation component (710) for providing an output signal (I ) indicating an estimated proximity according to the magnitude indicated by the sensing signal. prox1 ).

3. The proximity sensor module according to claim 1, wherein: The signal processor (7) has a proximity estimation component (720, 730) for providing an indication of a component (I sG ,I sB ) relative to the other component of the sensing signal (I sR ) is close to the output signal (I prox2 ,I prox3 ).

4. The proximity sensor module according to claim 1, wherein: The signal processor (7) has a proximity estimation component (740) for providing an output signal (I ) indicating an estimated proximity based on a temporal variation in the magnitude of the sensing signal. prox4 ).

5. The proximity sensor module according to claim 1, wherein: The signal processor (7) has a proximity estimation component (750) for providing an output signal (I) indicative of an estimated proximity indicated by the amplitude of an AC component in the frequency range of 50-220 Hz. prox5 ).

6. A proximity sensor module according to one of claims 2 to 5, comprising a combination component for generating an output signal (I ) indicating an estimated proximity based on an output signal from the proximity estimation component specified therein. prox ).

7. A proximity sensitive display element, comprising, in addition to the proximity sensor module according to any one of claims 1 to 6, A light guide (10), the light guide (10) comprising a substrate (11), the substrate (11) having a first main side (12) and a second main side (14) opposite to each other, the first main side (12) and the second main side (14) having a first reflective layer (22) and a second reflective layer (24), respectively, the first reflective layer (22) and the second reflective layer (24) having reflective inner surfaces (222, 242) facing the interior of the light guide, at least one window (16) being defined in the first main side to allow optical radiation to enter and leave the light guide; at least one light emitting element (30) at the second main side of the substrate to generate light radiation in the light guide, At least one IR sensor (40) is arranged on the second main side of the substrate, the at least one IR sensor (40) faces the first main side through the semi-transparent patch (240) in the second reflective layer (24), the IR sensor is one of a plurality of proximity sensors of different types selected from capacitive sensors, pressure sensors, near infrared sensors and mid-infrared sensors, the proximity sensor module further comprising an output unit to generate a result proximity signal based on an input proximity signal emitted by the proximity sensor, wherein the output unit comprises a selection unit and a controller, and if the estimated value of the sensor is within the sensitivity range of the proximity sensor, the selection unit is caused to select the input proximity signal from a specific proximity sensor among the proximity sensors.

8. The proximity-sensitive display element (1) according to claim 7, comprising: A sensor array having a plurality of IR sensors distributed on the second main side, the plurality of IR sensors facing the first main side through corresponding semi-transparent patches, wherein the at least one IR sensor (40) is one of the IR sensors.

9. The proximity sensitive display element according to claim 7, wherein: The semi-transparent patch (240) is arranged as a region where the second reflective layer is patterned into a grid.

10. The proximity-sensitive display element according to one of claims 7 to 9, wherein: The first reflective layer (22) is arranged between the light guide (10) and the opaque layer (26).

11. The proximity sensitive display element according to claim 10, wherein: The opaque layer (26) has one or more protrusions (262) extending towards the first major side (12) of the light guide.

12. A proximity-sensitive display panel comprising an assembly of proximity-sensitive display elements according to one of claims 7 to 11.

13. A method of sensing proximity to an outer surface (161) of a translucent window (16), comprising: - emitting light radiation with at least one light emitting element (30) and transmitting said light radiation through said translucent window; - generating a sensing signal indicative of said light radiation emitted by said at least one light emitting element (30) and reflected by a human finger (F) through the translucent window; - calculating from the sensed signal an indication of the pressure exerted by the human finger (I press ), wherein the sensing signal has at least a first signal component and a second signal component, the first signal component and the second signal component are respectively indicative of a red spectral component and a green spectral component in the optical radiation, and wherein a ratio between the red signal component and the green signal component is calculated as the indication of pressure.

Images