CN117926189A - Color coating with diamond-like carbon layer - Google Patents

Abstract

The present disclosure relates to color coatings with diamond-like carbon layers. An electronic device, such as a wristwatch, that may be provided with a conductive structure. These conductive structures may include sensor electrodes for Electrocardiogram (ECG) sensors. A coating may be provided on the sensor electrode to reflect visible light of a particular wavelength so that the sensor electrode assumes a desired color. The coating may include adhesion and transition layers on the sensor electrode, opaque colored layers on the adhesion and transition layers, and a thin film interference filter on the opaque colored layer. The thin film interference filter may have an uppermost diamond-like carbon (DLC) layer. The DLC layer can contribute to the color response of the coating while minimizing noise in the ECG waveform collected by the ECG sensor using the sensor electrodes.

Description

Color coating with diamond-like carbon layer

The present application claims priority from U.S. patent application Ser. No. 18/487,004, filed on day 13 of 10, 2023, and U.S. provisional patent application Ser. No. 63/419,613, filed on day 26 of 10, 2022, which are incorporated herein by reference in their entirety.

Technical Field

The present disclosure relates generally to coatings for electronic device structures, and more particularly, to visible light reflective coatings for conductive electronic device structures.

Background

Electronic devices such as cellular telephones, computers, watches, and other devices contain conductive structures, such as conductive housing structures. The conductive structure is provided with a coating that reflects light of a particular wavelength such that the conductive member exhibits a desired visible color.

Providing a coating such as one having a desired color brightness can be challenging. Furthermore, if careless, the coating may exhibit unsatisfactory optical performance under different operating environments and conductive structure geometries, and may adversely degrade the performance of other equipment components, such as sensors.

Disclosure of Invention

The electronic device may include conductive structures, such as sensor electrodes for Electrocardiogram (ECG) sensors. ECG sensors can collect ECG data using sensor electrodes. A visible light reflective coating may be provided on the sensor electrode.

The visible light reflective coating can have an adhesion and transition layer, an opaque colored layer on the adhesion and transition layer, and a thin film interference filter on the opaque colored layer. The thin film interference filter may have an uppermost layer including diamond-like carbon (DLC). For example, the thin film interference filter may have a lowermost CrC layer. As two examples, the opaque colored layer may comprise TiCN or TiCrCN.

The thin film interference filter and DLC layer can help impart a light yellow or gold color to the coating and thus to the sensor electrode. Meanwhile, the DLC layer can reduce Faraday current between the sensor electrode and the skin, can reduce double-layer capacitance between the sensor electrode and the skin, and can reduce the water cone angle of water on the coating. This can be used to minimize noise in the ECG data collected using the sensor electrodes, thereby helping to ensure that accurate ECG data is collected over time.

One aspect of the present disclosure provides an apparatus. The device may include a conductive substrate. The device may include a coating on the conductive substrate and having a color. The coating may include adhesion and transition layers. The coating may include a thin film interference filter on the adhesion and transition layers, wherein the thin film interference filter includes a diamond-like carbon (DLC) layer.

Another aspect of the present disclosure provides an apparatus. The device may include a conductive substrate. The device may include a coating on the conductive substrate and having a color. The coating may include adhesion and transition layers. The coating may include an opaque layer over the adhesion and transition layers. The coating may include a bilayer thin film interference filter having an uppermost layer comprising diamond-like carbon (DLC) on the opaque layer.

Yet another aspect of the present disclosure provides an electronic device. The electronic device may include a housing. The electronic device may include a display mounted to the housing. The electronic device may include a sensor electrode on the housing. The electronic device may include circuitry configured to collect sensor data using the sensor electrodes. The electronic device may include a coating on the sensor electrode and having a color, wherein the coating includes a diamond-like carbon (DLC) layer forming part of a thin film interference filter.

Drawings

Fig. 1 is a perspective view of an exemplary electronic device of the type that may be provided with a conductive structure and a visible light reflective coating, according to some embodiments.

Fig. 2 is a cross-sectional side view of an exemplary electronic device having a conductive structure that may be provided with a visible light reflective coating, according to some embodiments.

Fig. 3 is an exploded cross-sectional side view of an exemplary conductive housing sidewall that may be provided with a visible light reflective coating, according to some embodiments.

FIG. 4 is a cross-sectional side view of an exemplary visible light reflective coating having a multilayer interference film including an uppermost diamond-like carbon (DLC) layer, according to some embodiments.

FIG. 5 is a cross-sectional side view of exemplary layers in a visible light reflective coating having a multilayer interference film with an uppermost DLC layer, according to some embodiments.

Fig. 6 is a diagram of an L x b x color space of an exemplary visible light reflective coating of the type shown in fig. 4 and 5, according to some embodiments.

Fig. 7 is a diagram illustrating how an exemplary visible light reflective coating of the type shown in fig. 4 and 5 may be disposed on a sensor electrode, according to some embodiments.

Fig. 8 is a diagram illustrating how an exemplary visible light reflective coating of the type shown in fig. 4 and 5 may reduce noise in sensor data collected by an underlying sensor electrode, according to some embodiments.

FIG. 9 is a ternary phase diagram showing how an exemplary DLC layer may be provided with an sp ³ -rich composition to minimize noise in sensor data collected by an underlying sensor electrode, according to some embodiments.

FIG. 10 is a cross-sectional side view of an exemplary layer in a visible light reflective coating having a three layer interference film with an uppermost DLC layer, according to some embodiments.

Detailed Description

Electronic devices and other items may be provided with conductive structures. These conductive structures may include sensor electrodes for Electrocardiogram (ECG) sensors. A coating may be formed on the sensor electrode to reflect visible light of a specific wavelength so that the sensor electrode assumes a desired color. The coating may include adhesion and transition layers on the sensor electrode, opaque colored layers on the adhesion and transition layers, and a thin film interference filter on the opaque colored layer. The thin film interference filter may have an uppermost diamond-like carbon (DLC) layer. The DLC layer can contribute to the color response of the coating, thereby helping to configure the coating to exhibit a strong pale yellow or gold color. At the same time, the DLC layer can be used to minimize noise in the ECG waveform collected by the ECG sensor using the sensor electrodes.

Fig. 1 shows an exemplary electronic device of the type that may be provided with a conductive structure and a visible light reflective coating. The electronic device 10 of fig. 1 may be a computing device such as a laptop computer, a computer monitor including an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wristwatch device (e.g., a wristwatch with a wristband), a hanging device, a headset or earpiece device, a device embedded in glasses or other equipment worn on the user's head (e.g., a headset device), or other wearable or miniature device, a television, a computer display not including an embedded computer, a gaming device, a navigation device, an embedded system (such as a system in which electronic equipment with a display is installed in a kiosk or automobile), a wireless base station, a home entertainment system, a wireless speaker device, a wireless access point, equipment implementing the functionality of two or more of these devices, or other electronic equipment. In the exemplary configuration of fig. 1, the device 10 is a portable device such as a wristwatch (e.g., a smartwatch). Other configurations may be used for the device 10 if desired. The example of fig. 1 is merely illustrative.

In the example of fig. 1, device 10 includes a display, such as display 14. The display 14 may be mounted in a housing, such as housing 12. The outer shell 12, which may sometimes be referred to as a housing or case, may be formed of plastic, glass, ceramic, fiber composite, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of any two or more of these materials. The housing 12 may be formed using a unitary configuration in which a portion or all of the housing 12 is machined or molded into a single structure, or may be formed using multiple structures (e.g., an internal frame structure, one or more structures forming an external housing surface, etc.). The housing 12 may have metal sidewalls or sidewalls formed of other materials. Examples of metallic materials that may be used to form housing 12 include stainless steel, aluminum, silver, gold, titanium, metal alloys, or any other desired conductive material.

The display 14 may be formed on (e.g., mounted on) the front side (face) of the device 10. The housing 12 may have a rear housing wall on a rear side (rear) of the device 10 opposite the front of the device 10. Conductive housing sidewalls in housing 12 may surround the perimeter of device 10. The rear housing wall of housing 12 may be formed of a conductive material and/or an insulating material.

The rear housing wall of housing 12 and/or display 14 may extend across some or all of the length (e.g., parallel to the X-axis of fig. 1) and width (e.g., parallel to the Y-axis) of device 10. The conductive side walls of the housing 12 may extend across some or all of the height of the device 10 (e.g., parallel to the Z-axis).

The display 14 may be a touch screen display that incorporates conductive capacitive touch sensor electrode layers or other touch sensor components (e.g., resistive touch sensor components, acoustic touch sensor components, force-based touch sensor components, light-based touch sensor components, etc.), or may be a non-touch sensitive display. The capacitive touch screen electrode may be formed from an array of indium tin oxide pads or other transparent conductive structures.

Display 14 may include an array of display pixels formed from Liquid Crystal Display (LCD) components, an array of electrophoretic display pixels, an array of plasma display pixels, an array of Organic Light Emitting Diode (OLED) display pixels, an array of electrowetting display pixels, or display pixels based on other display technologies.

The display 14 may be protected using a display overlay. The display cover layer may be formed of a transparent material such as glass, plastic, sapphire or other crystalline insulating material, ceramic or other transparent material. For example, the display overlay may extend across substantially the entire length and width of the device 10.

The device 10 may include a button such as button 8. There may be any suitable number of buttons in the device 10 (e.g., a single button, more than one button, two or more buttons, five or more buttons, etc.). A button such as button 8 may be located in an opening in housing 12 or in an opening in display 14 (as examples). Buttons such as button 8 may be rotary buttons, sliding buttons, buttons actuated by pressing a movable button member, buttons that may receive user input by rotation, touch, and/or pressing, and the like. The button member for a button such as button 8 may be formed of metal, glass, plastic, or other materials. The button members for a button such as button 8 may also form sensor electrodes for one or more sensors in device 10, if desired. In the case where the device 10 is a wristwatch device, the button 8 may sometimes be referred to as a crown.

A cross-sectional side view of the device 10 in an exemplary configuration with a display 14 having a display overlay is shown in fig. 2. As shown in fig. 2, display 14 may have one or more display layers forming pixel array 18. During operation, pixel array 18 forms an image for a user in an active area of display 14. Display 14 may also have inactive areas (e.g., areas along the boundaries of pixel array 18) that are pixel-free and do not produce an image. The display overlay 16 of fig. 2 overlaps the pixel array 18 in the active area and overlaps the electronic components in the device 10.

The display cover layer 16 may be formed of a transparent material such as glass, plastic, ceramic, or crystalline material (e.g., sapphire). Exemplary configurations of display overlays and other transparent members in the device 10 (e.g., windows formed within openings of the housing 12 for cameras or other light-based devices) formed from hard transparent crystalline materials such as sapphire, sometimes referred to as corundum or crystalline alumina, are sometimes described herein as examples. Sapphire constitutes a satisfactory material for display covers and windows due to its hardness (9 mohs hardness). In general, however, these transparent members may be formed of any suitable material.

The display overlay 16 of the display 14 may be planar or curved and may have a rectangular profile, a circular profile, or a profile of other shapes. If desired, openings may be formed in the display cover layer. For example, an opening may be formed in the display cover to accommodate a button such as button 8, a speaker port, or other component. Openings may be formed in the housing 12 to form communication or data ports (e.g., audio jack ports, digital data ports, ports for a Subscriber Identity Module (SIM) card, etc.), to form openings for buttons, or to form audio ports (e.g., openings for speakers and/or microphones).

If desired, the device 10 may be coupled to a strap, such as strap 28 (e.g., in the case where the device 10 is a wristwatch device). Strap 28 may be used to hold device 10 on a user's wrist (as an example). The strap 28 may sometimes be referred to herein as a wristband 28. In the example of fig. 2, wristband 28 is connected to an attachment structure 30 in housing 12 at an opposite side of device 10. The attachment structure 30 may include lugs, pins, springs, clamps, brackets, and/or other attachment mechanisms that configure the housing 12 to receive the wristband 28. Configurations that do not include straps may also be used with the device 10.

If desired, a light-based component, such as light-based component 24, may be mounted in alignment with opening 20 in housing 12. The opening 20 may be circular, may be rectangular, may have an oval shape, may have a triangular shape, may have other shapes with straight and/or curved edges, or may have other suitable shapes (profile when viewed from above). Window member 26 may be mounted in window opening 20 of housing 12 such that window member 26 overlaps component 18. A gasket, washer, adhesive, screw, or other fastening mechanism may be used to attach window member 26 to housing 12. The surface 22 of the window member 26 may be flush with the outer surface 23 of the housing 12, may be recessed below the outer surface 23, or may protrude from the outer surface 23 as shown in fig. 3 (e.g., the surface 22 may be in a plane protruding away from the surface 23 in the-Z direction). In other words, window member 26 may be mounted to a protruding portion of housing 12. The surface 23 may, for example, form a back surface of the housing 12.

The conductive structures in the device 10 may be provided with a visible light reflective coating that reflects light of certain wavelengths such that the conductive structures exhibit a desired aesthetic appearance (e.g., desired color, reflectivity, etc.). The conductive structures in the device 10 may include, for example, conductive portions of the housing 12 (e.g., conductive side walls of the device 10, conductive rear walls of the device 10, protruding portions of the housing 12 for mounting the window member 26, etc.), attachment structures 30, conductive portions of the wristband 28, conductive mesh, conductive members 32, and/or any other desired conductive structures on the device 10.

Conductive component 32 may include internal components (e.g., internal housing members, conductive frames, conductive mounts, conductive support plates, conductive brackets, conductive clamps, conductive springs, input-output components or devices, etc.), components located inside and outside device 10 (e.g., conductive SIM card holders or SIM card ports, data ports, microphone ports, speaker ports, conductive button members for buttons 8, etc.), components mounted at the outside of device 10 (e.g., conductive portions of band 28, such as clasps for band 28), and/or any other desired conductive structure on device 10.

As shown in fig. 2, the device 10 may also include one or more sensors, such as sensor 31. The sensor 31 may generate (e.g., collect, sense, or measure) sensor data using one or more conductive members 32. The sensor 31 may include, for example, an optical sensor that collects optical sensor data using the conductive member 32, a touch sensor that detects a touch of a user using the conductive member 32, a force sensor that detects a force applied to the device 10 using the conductive member 32, a temperature sensor that collects temperature data using the conductive member 32, or any other desired sensor.

The sensor 31 is described herein as an example of a specific implementation of an Electrocardiogram (ECG) sensor that uses conductive members 32 to collect ECG data. The ECG data can include measurements of the electrical activity (e.g., electrical potential) of the user's heart when one or more conductive members 32 are in contact with the user's body. For example, the conductive members 32 protruding through the housing 12 may form sensor electrodes (e.g., ECG sensor electrodes) that measure ECG data when the device 10 is worn by a user on their wrist (e.g., the sensor 31 may include a first conductive member 32 that forms a first sensor electrode protruding through the rear housing wall of the device 10 beyond the outer surface 23 opposite the display 14, and/or may include a second conductive member 32 that forms a second sensor electrode located on the button 8 or a second sensor electrode formed by the button 8).

Fig. 3 is an exploded cross-sectional side view of a conductive sidewall in the device 10 that may be provided with a visible light reflective coating. As shown in fig. 3, the housing 12 may include peripheral conductive housing structures such as conductive sidewalls 12W. The conductive sidewall 12W may extend around a lateral periphery of the device 10, for example, in the X-Y plane (e.g., the conductive sidewall 12W may extend around the periphery of the display 14 of fig. 2 and may serve as a conductive bezel of the display).

The conductive sidewall 12W may include one or more ledges 34. Ledge 34 may be used to support a conductive and/or dielectric back wall of device 10 (e.g., at the back of device 10) and/or support display overlay 16 of fig. 2 (e.g., at the front of device 10). To provide the conductive sidewall 12W with a desired visible color, a visible light reflective coating such as coating 36 may be deposited on the conductive sidewall 12W (e.g., all of the conductive sidewall 12W, portions of the conductive sidewall 12W at the exterior of the device 10, etc.). The coating 36 may also be deposited on other conductive structures in the device 10 (e.g., the conductive member 32 of fig. 2, other conductive portions of the housing 12, etc.).

In practice, the coating may have different thicknesses over its surface area due to variations in the underlying geometry of the conductive structure (e.g., due to limitations of the coating deposition equipment to deposit a uniform coating over the entire underlying geometry). For example, the coating 36 of fig. 3 may exhibit a first thickness T1 at the bottom and top edges of the conductive sidewall 12W (e.g., the conductive sidewall 12W exhibits a curved three-dimensional shape), but may exhibit a second thickness T2 along the center of the conductive sidewall 12W (e.g., the conductive sidewall 12W exhibits a substantially flat shape). The thickness T2 may represent the maximum thickness (e.g., 100% thickness) of the coating 36 over its entire surface area. Thickness T1 may be less than thickness T2 (e.g., 30% to 70% of thickness T2). If careless, the thickness variation along the surface area of the coating 36 can undesirably alter the color of the visible light reflected by the coating, thereby altering the aesthetic appearance of the underlying conductive structure.

Although fig. 3 shows how the thickness of the coating 36 may vary across the conductive sidewall 12W, the thickness of the coating 36 may also vary across different portions of the conductive member 32 of fig. 2 and/or between different conductive structures on the device 10 based on the underlying surface geometry. It may be desirable to provide housing 12 and conductive member 32 (e.g., sensor electrode of sensor 31) with a coating 36 that imparts a desired uniform color to all visible portions of device 10, thereby imparting a desired aesthetic appearance, although the thickness of the coating varies as the underlying surface geometry varies across the side surface area of the coating.

Meanwhile, if care is taken, the placement of the coating 36 on the sensor electrodes of the sensor 31 may undesirably reduce the quality of the sensor data generated by the sensor 31 (e.g., may result in excessive noise in the ECG data generated using the sensor electrodes). To alleviate these problems and to configure the coating 36 to impart a desired visible color to the sensor electrodes of the sensor 31 (and other conductive structures of the device 10) that does not change with thickness and does not undesirably reduce the quality of sensor data generated by the sensor electrodes of the sensor 31, the coating 36 may include a multilayer thin film interference filter having an uppermost diamond-like carbon (DLC) layer.

Fig. 4 is a cross-sectional view of a visible light reflective coating with a multilayer thin film interference filter having an uppermost DLC layer (e.g., for lamination to sensor electrodes of sensor 31 and other conductive structures in device 10). As shown in fig. 4, a visible light reflective coating such as coating 36 may be disposed (e.g., deposited, laminated, formed, etc.) on a conductive substrate such as substrate 35. Substrate 35 may be a conductive structure in device 10, such as conductive member 32 (e.g., a sensor electrode of sensor 31 protruding through a back wall of device 10 and/or a sensor electrode of sensor 31 disposed on or formed by button 8 of fig. 2), a conductive portion of housing 12 (fig. 1 and 2), or conductive sidewall 12W (fig. 3).

The substrate 35 may be thicker than the coating 36. The thickness of substrate 35 may be 0.1mm to 5mm, greater than 0.3mm, greater than 0.5mm, between 5mm and 20mm, less than 5mm, less than 2mm, less than 1.5mm, or less than 1mm (as examples). Substrate 35 may comprise stainless steel, aluminum, titanium, or other metals or alloys. In other suitable arrangements, substrate 35 may be an insulating substrate, such as a ceramic substrate, a glass substrate, or a substrate formed of other materials.

Coating 36 may include an adhesion and transition layer 40 on substrate 35. The coating 36 may include an opaque coloring layer, such as an opaque coloring layer 42, on the adhesion and transition layer 40. Coating 36 may include a multilayer thin film interference filter, such as Thin Film Interference Filter (TFIF) 38, on opaque colored layer 42. An optional oleophobic coating or other film, coating or layer (e.g., a layer that does not substantially contribute to the color response of the coating) can be laminated to thin film interference filter 38 if desired.

The opaque coloring layer 42 may, for example, have a first lateral surface that is in direct contact with the adhesion and transition layer 40, and may have a second lateral surface opposite the first lateral surface. The thin film interference filter 38 may, for example, have a third lateral surface that directly contacts the second lateral surface, and may have a fourth lateral surface opposite the third lateral surface (e.g., the fourth lateral surface may form an uppermost or outermost layer of the coating 36). The thin film interference filter 38 may include a plurality of layers (films) stacked on the opaque colored layer 42. In some implementations, the thin film interference filter 38 may include two stacked layers (films). In other implementations, the thin film interference filter 38 may include three or more stacked layers (films) or a single layer (film).

The layers of coating 36 may be deposited on substrate 35 using any suitable deposition technique. Examples of techniques that may be used to deposit the layers in coating 36 include Physical Vapor Deposition (PVD) (e.g., evaporation and/or sputtering), cathodic arc deposition, chemical vapor deposition, ion plating, laser ablation, and the like. For example, coating 36 may be deposited on substrate 35 in a deposition system having a deposition apparatus (e.g., a cathode). The substrate 35 may be moved (e.g., rotated) within the deposition system as the deposition equipment (e.g., cathode) deposits the layers of coating 36. If desired, the substrate 35 may be dynamically moved/rotated during deposition relative to the speed and/or orientation associated with the deposition equipment (e.g., cathode). This may help to provide coating 36 with as uniform a thickness as possible over its entire area, even where substrate 35 has a three-dimensional shape (e.g., minimizing the difference between thicknesses T1 and T2 of fig. 3).

The thin film interference filter 38 may be formed from a stack of materials such as inorganic and/or organic dielectric layers having different refractive indices. The layers of thin film interference filter 38 may include one or more layers having a higher refractive index value (sometimes referred to as a "high" refractive index value) and one or more layers having a lower refractive index value (sometimes referred to as a "low" refractive index value). Layers with higher refractive index values may be interleaved with layers with lower refractive index values, if desired.

Incident light may be transmitted through each of the layers in the thin film interference filter 38 while also being reflected from the interfaces between each of the layers, as well as at the interfaces between the thin film interference filter and the opaque colored layer 42 and the interface between the thin film interference filter and air. By controlling the thickness and refractive index (e.g., composition) of each layer in the thin film interference filter 38, light reflected at each interface can destructively and/or constructively interfere at a selected set of wavelengths such that reflected light emerging from the thin film interference filter 38 is perceived by an observer in a desired color and brightness over a corresponding range of viewing angles (e.g., angles of incidence, e.g., from 0 degrees to 60 degrees relative to a normal axis of the conductive structure), while exhibiting a relatively constant response throughout the lateral area of the coating, even when deposited on an underlying substrate 35 having a three-dimensional (e.g., curved) shape.

Unlike the layers of thin film interference filter 38, opaque colored layer 42 is substantially opaque and does not transmit light incident on coating 36. On the other hand, the opaque colored layer 42 may reflect incident light received through the thin film interference filter 38 toward and back through the thin film interference filter 38. The thickness and/or composition of the opaque colored layer 42 may contribute to the color response of the light as it exits the coating 36, as observed by the user (e.g., in combination with the interference effects imparted by the thin film interference filter 38 on transmitted and reflected light). Opaque colored layer 42 may also be sometimes referred to herein as a non-interference filter layer or an inherently colored layer.

When coating 36 is laminated to the sensor electrodes of the sensor, thin film interference filter 38 may be provided with an uppermost DLC layer (e.g., the uppermost layer of thin film interference filter 38 may be a DLC layer) in order to optimize the performance of sensor 31 (fig. 2). FIG. 5 is a cross-sectional side view showing some exemplary compositions of coating 36, where thin film interference filter 38 has an uppermost DLC layer. Substrate 35 is omitted from fig. 5 for clarity.

As shown in fig. 5, adhesion and transition layer 40 may include an example layer 44 on substrate 35 and one or more transition layers, such as transition layer 46, on seed layer 44. Seed layer 44 may couple substrate 35 to transition layer 46 (e.g., transition layer 46 may be interposed between seed layer 44 and opaque coloring layer 42). In the example of fig. 5, the seed layer 44 is formed of chromium (Cr), and thus may sometimes be referred to herein as Cr layer 44 or Cr seed layer 44. The transition layer 46 may be formed of chromium nitride (CrN) or chromium silicon nitride (CrSiN), and thus may sometimes be referred to herein as a CrN layer 46, a CrSiN layer 46, a CrN transition layer 46, or a CrSiN transition layer 46.

This is merely illustrative. In general, seed layer 44 and/or transition layer 46 may include chromium nitride (CrN), chromium silicon (CrSi), titanium (Ti), chromium silicon nitride (CrSiN), chromium silicon carbonitride (CrSiCN), chromium silicon carbide (CrSiC), chromium carbonitride (CrCN), other metals, metal alloys, and/or other materials.

In the example of fig. 5, thin film interference filter 38 is a two-layer interference filter having a first layer 48 and a second layer 50. The first layer 48 may be the lowermost (bottom) layer of the thin film interference filter 38 laminated to the opaque colored layer 42. Layer 48 may have a thickness T2. The second layer 50 may be the uppermost (top) layer 50 of the thin film interference filter 38 laminated to layer 48. Layer 50 may have a thickness T1. The thicknesses T1 and T2 and the compositions of layers 48 and 50 may be selected to impart a desired interference effect to thin film interference filter 38 on transmitted and reflected light to configure coating 36 to reflect visible light in a desired visible color response.

As one example, layer 48 may comprise chromium carbide (CrC), and thus may sometimes be referred to herein as CrC layer 44. Layer 50 may comprise DLC and may therefore sometimes be referred to herein as DLC layer 50.DLC is an amorphous synthetic carbon material with a relatively large number of sp ³ hybridized carbon atoms (e.g., the ratio of sp ³ hybridized atoms to other atoms exceeds a threshold level), which imparts diamond-like properties to the material (e.g., diamond-like hardness, smoothness, etc.). DLC may also contain one or more fillers (e.g., non-sp ³ hybridized atoms), such as sp ² hybridized carbon (e.g., graphitic carbon) and/or hydrogen. DLC layer 50 may also sometimes be referred to herein as carbon flash layer 50 or carbon flash DLC layer 50.

The example of fig. 5 is merely illustrative. If desired, thin film interference filter 38 may include more than two layers (e.g., where DLC layer 50 forms the uppermost layer of the interference filter) or a single layer (e.g., DLC layer 50). The opaque coloring layer 42 may comprise titanium carbonitride (TiCN), titanium chromium carbonitride (TiCrCN), or any other desired metal, metal alloy, and/or other material. Thus, the opaque colored layer 42 may sometimes be referred to herein as a TiCN layer 42 or TiCrCN layer 42.

The composition of DLC layer 50 and CrC layer 48, as well as thicknesses T1 and T2, may be selected such that coating 36 exhibits a desired color over a predetermined range of angles of incidence. Both thicknesses T1 and T2 may be less than the thickness of opaque colored layer 42 (e.g., opaque colored layer 42 may be thicker than the sum of thicknesses T1 and T2). If desired, thickness T1 may be less than thickness T2. The thickness T1 may be, for example, 10nm to 30nm, 15nm to 25nm, 18nm to 22nm, 5nm to 35nm, 1nm to 50nm, 1nm to 100nm, 10nm to 60nm, 8nm to 23nm, 18nm to 38nm, or other thickness. The thickness T2 may be, for example, 20nm-30nm, 10nm-40nm, 22nm-28nm, 15nm-35nm, 1nm-50nm, 1nm-100nm, 10nm-60nm, 21nm-45nm, or other thickness.

Fig. 6 is a graph of an exemplary color response of coating 36 in the L x b x color space. As shown in fig. 6, the thicknesses T1 and T2 and the compositions of layers 48 and 50 may be selected to produce an interference effect on transmitted and reflected visible light that configures coating 36 to appear color within region 52 (e.g., an L x value greater than threshold L _TH1 and less than threshold L _TH2, and a b x value greater than threshold b _TH1 and less than threshold b _TH2).

The threshold b _TH1 may be between 0-10, 5-12, 8-12, 6-12, greater than 0, greater than 4, greater than 5, greater than 6, greater than 8, less than 10, less than 12, less than 15, or other values. Threshold b _TH2 may be between 12-16, 10-20, greater than 10, greater than 12, greater than 14, greater than 15, less than 14, less than 12, less than 20, or other values greater than threshold b _TH1. Threshold L _TH1 may be between 55-70, 60-70, 67-72, greater than 50, greater than 60, greater than 65, greater than 67, greater than 70, less than 72, less than 75, or other values. Threshold L _TH2 may be between 60-75, 71-75, greater than 65, greater than 70, greater than 72, greater than 73, less than 75, less than 80, or other values greater than threshold L _TH1.

This may configure the coating 36 to present a light gold, yellow, or champagne color of the device 10, for example. In this manner, DLC layer 50 may facilitate the visible light interference effect of thin film interference filter 38 (e.g., may form a portion of thin film interference filter 38), thereby facilitating imparting a desired visible color response to coating 36 (e.g., facilitating placement of the color response of coating 36 within region 52 of fig. 6). The example of fig. 6 is merely illustrative. In practice, the region 52 may have other shapes.

In addition to contributing to the visible light interference effect of thin film interference filter 38, DLC layer 50 may also help optimize the performance of sensor 31 (fig. 2) in collecting sensor data (e.g., ECG data). Fig. 7 is a diagram showing how a conductive member 32 provided with a coating 36 may be used to collect sensor data such as ECG data (e.g., in implementations where the coated conductive member 32 is a sensor electrode of the sensor 31 of fig. 2).

As shown in fig. 7, the sensor 31 may include a sensor circuit 56 coupled to one or more conductive members 32 (e.g., one or more sensor electrodes of the sensor 31) via one or more signal paths 54. Sensor circuit 56 may include analog and/or digital circuitry (e.g., voltmeters, ammeter, multimeters, power detectors, phase detectors, receivers, etc.) that measure power, voltage, current, phase, and/or any other desired electrical signal characteristic (waveform) over time.

The coating 36 may be disposed on the conductive member 32. When a user's body 64 (e.g., skin at the user's wrist, user's finger, etc.) contacts a sensor electrode (e.g., coating 36), an electrical signal (current) is transferred from body 64 to the sensor electrode through signal path 54 and to sensor circuit 56. The electrical signal may include an intrinsic ECG waveform 58 generated by the electrical activity of the user's heart, which is then received as waveform 62 at the sensor circuit 56.

The sensor electrodes are desirably dry electrodes for ECG sensing. The sensor circuit 56 may receive and measure (e.g., record, sense, generate, etc.) the electrical waveform 62 (e.g., as sensor data or ECG data) through the signal path 54. Sensor circuit 56 and/or other control circuitry (e.g., one or more processors, such as central processing units, microprocessors, application specific integrated circuits, graphics processing units, etc.) on device 10 may process waveform 62 to characterize and monitor the user's body and health over time, to detect the occurrence of undesirable cardiac events (e.g., atrial fibrillation), and/or to perform any other desired processing operations.

However, if careless, the sensor electrode may experience a relatively high level of noise at the skin-electrode interface (sometimes referred to herein as interface noise). High interface noise may negatively impact the accuracy of the ECG detection algorithm implemented by the sensor 31, which may compromise clinical accuracy and/or reduce user experience.

For example, chemical reactions at the skin-electrode interface (e.g., resulting from interactions between electrical signals on the body 64 and salts) can produce a peak faraday current 60 from the intrinsic ECG waveform 58. In addition to generating a peak faraday current, noise may also be introduced into the electrical signal (e.g., into the waveform 62 received at the sensor circuit 56) by the double layer capacitance between the sensor electrode and the body 64 and/or by the surface hydrophobicity of the sensor electrode and the coating 36.

These imperfections may result in electrical signals being received and measured (e.g., sensed or collected) at the sensor circuit 56, with a significant amount of noise present in the waveform 62. In other words, if careless, the inherently weak ECG signal combined with the peak faraday current and/or other interface noise may cause the control circuitry to perform an incorrect or uncertain classification of the user's current ECG waveform.

The double layer capacitance acts as a transducer at the dry skin-electrode interface. The human body contains organic ions such as sodium, potassium and chloride ions, while electrons conduct electrical signals on the dry sensor electrodes. A double layer capacitance is created by the electrons and ions at this interface (e.g., due to sweat present between the body 64 and the sensor electrodes) that converts the inorganic ions into electrons that are received at the sensor circuit 56 for recording physiological signals.

Meanwhile, when the finger contacts a hard surface, a large friction force is generated due to the increase of the contact area, and the finger is caught by sweat glands Kong Runshi, thereby increasing the contact area. The hydrophilic interface with the electrode may produce a smaller water cone angle for moisture than the hydrophobic interface, which produces more surface beading for moisture and thus a larger water cone angle. Smaller water cone angles may produce less noise in the electrical signal than larger water cone angles. In other words, the hydrophilic interface can stabilize the double layer capacitance and reduce accidental charge/discharge current at the surface, thereby reducing interface noise.

The inclusion of DLC layer 50 (fig. 5) as the uppermost layer in coating 36 may serve to mitigate or reduce this interface noise, thereby minimizing noise in waveform 62 received at sensor circuit 56 (e.g., minimizing noise in the sensor data collected by sensor 31). Fig. 8 is a diagram illustrating how the inclusion of DLC layer 50 (fig. 5) as the uppermost layer in coating 36 may be used to mitigate or reduce interface noise.

In implementations where coating 36 does not include DLC layer 50, data 65 of fig. 8 characterizes noise (in uVrms units) of waveform 62, and thus characterizes sensor data collected by sensor circuit 56, when body 64 contacts coating 36 and the sensor electrode (fig. 7). In implementations where coating 36 includes DLC layer 50 as the uppermost layer of thin film interference filter 38, data 66 characterizes the noise of waveform 62, and thus the sensor data collected by sensor circuit 56, when body 64 contacts coating 36 and the sensor electrode (fig. 7). As shown in data 65 and 66, DLC layer 50 is included to significantly reduce noise in the collected sensor data (as indicated by arrow 68). At the same time, DLC layer 50 contributes visible light interference effects to thin film interference filter 38, which contributes to the overall color response of coating 36 (e.g., within region 52 of FIG. 6).

DLC layer 50 can be used to reduce noise in waveform 62 due to its chemical inertness (e.g., minimizing the generation of spike faraday currents as shown in waveform 60 of fig. 7), its surface hydrophilicity (e.g., minimizing the water contact angle of moisture on the sensor electrode), and its reduced double layer capacitance at the skin-electrode interface. This reduction in noise may maximize the accuracy with which the sensor circuit 56 measures the electrical activity of the user's heart, the clinical accuracy of detecting certain health events (e.g., atrial fibrillation events) based on the collected sensor data, and the overall user experience of the device 10.

The composition of DLC layer 50 may also be selected to further minimize noise in the collected sensor data. Fig. 9 is a ternary phase diagram showing how the composition of DLC layer 50 is selected to further minimize noise in the collected sensor data. As shown in fig. 9, the relative composition of DLC layer 50 may be plotted on a ternary phase diagram having a first angle 74 corresponding to pure diamond-like carbon (e.g., pure sp ³ hybridized carbon), a second angle 72 corresponding to pure graphite-like carbon (e.g., pure sp ² hybridized carbon), and a third angle 70 corresponding to pure hydrocarbon. When hydrocarbons are added to pure graphite-like carbon, the composition (phase) moves away from angle 72 along the horizontal axis toward angle 70, when diamond-like carbon is added to pure graphite-like carbon, the composition moves away from angle 72 along the first diagonal axis toward angle 74, when hydrocarbons are added to pure diamond-like carbon, the composition moves away from angle 74 along the second diagonal axis toward angle 70, and so forth.

To maximize the sensor noise reduction produced by DLC layer 50, DLC layer 50 may have a relatively high ratio of sp ³ hybridized carbon to sp ² hybridized carbon and a relatively high ratio of sp ³ hybridized carbon to hydrocarbons in DLC layer 50. For example, DLC layer 50 may have a composition that lies within region 76 of the ternary phase diagram of fig. 9 to minimize noise in the waveforms received by sensor circuit 56. In other words, DLC layer 50 may have a composition with a ratio of sp ³ hybridized carbon to sp ² hybridized carbon that exceeds threshold level B and a ratio of sp ³ hybridized carbon to hydrocarbon that exceeds threshold level a (e.g., region 76 may be above thresholds a and B). The threshold a may be 50%, 60%, 70%, 80%, 90%, 95%, greater than 50%, greater than 40%, greater than 60%, greater than 70%, greater than 80%, greater than 90%, greater than 95%, or other value. Threshold B may be 50%, 60%, 70%, 80%, 90%, 95%, greater than 50%, greater than 40%, greater than 60%, greater than 70%, greater than 80%, greater than 90%, greater than 95%, or other value. In practice, the region 76 may have other shapes.

The thin film interference filter 38 in the coating 36 may be a three layer thin film interference filter, if desired. Fig. 10 is a cross-sectional side view showing an exemplary composition for coating 36 in the example where thin film interference filter 38 is a three-layer thin film interference filter. Substrate 35 is omitted from fig. 5 for clarity.

As shown in fig. 10, the seed layer 44 may be formed of chromium (Cr), and thus may sometimes be referred to herein as a Cr layer 44 or Cr seed layer 44. The transition layer 46 may be formed of chromium silicon nitride (CrSiN), and thus may sometimes be referred to herein as a CrSiN layer 46. This is merely illustrative. In general, seed layer 44 and/or transition layer 46 may include chromium nitride (CrN), chromium silicon (CrSi), titanium (Ti), chromium silicon nitride (CrSiN), chromium silicon carbonitride (CrSiCN), chromium silicon carbide (CrSiC), chromium carbonitride (CrCN), other metals, metal alloys, and/or other materials.

In the example of fig. 6, thin film interference filter 38 is a three layer interference filter having a lowermost layer 80, an intermediate layer 48, and an uppermost layer 50. The lowermost layer 80 may comprise chromium silicon carbonitride (CrSiCN) and may therefore sometimes be referred to herein as CrSiCN layer 80. The intermediate layer 48 may comprise silicon carbide (SiC), and thus may sometimes be referred to herein as SiC layer 48. The uppermost layer 50 includes DLC (e.g., as in the implementation of fig. 5). CrSiCN layer 80 can have a thickness T3. The opaque coloring layer 42 may comprise titanium silicon nitride (TiSiN), and thus may sometimes be referred to herein as TiSiN layer 42.

The example of fig. 10 is merely illustrative. If desired, thin film interference filter 38 may include more than three layers (e.g., where DLC layer 50 forms the uppermost layer of the interference filter). The opaque coloring layer 42 may comprise titanium carbonitride (TiCN), titanium chromium carbonitride (TiCrCN), or any other desired metal, metal alloy, and/or other material.

The composition of DLC layer 50, siC layer 48, and CrSiCN layer 80, as well as the thicknesses T1-T3, may be selected such that coating 36 exhibits a desired color over a predetermined range of angles of incidence. By way of example, at the location of the peak or nominal coating thickness, the thickness T1 may be 10nm-20nm, 5nm-25nm, 1nm-30nm, 10nm-15nm, 5nm-17nm, 2nm-28nm, greater than 10nm, greater than 5nm, less than 20nm, less than 50nm, or other thickness. The thickness T2 may be 20nm-30nm, 10nm-40nm, 5nm-50nm, 25nm-35nm, 6nm-60nm, greater than 20nm, greater than 10nm, less than 30nm, less than 50nm, or other thickness. The thickness T3 may be 80nm-90nm, 70nm-100nm, 50nm-120nm, 25nm-95nm, 60nm-160nm, greater than 80nm, greater than 60nm, greater than 50nm, less than 100nm, less than 150nm, or other thickness.

The opaque coloring layer 42 may have an atomic percent of titanium atoms of 40% -50%, 30% -60%, 20% -70%, greater than 40%, greater than 30%, less than 50%, less than 60%, or other values. The opaque coloring layer 42 may have an atomic percent of silicon atoms of 1% -10%, 5% -12%, 3% -15%, greater than 5%, greater than 1%, less than 10%, less than 20%, or other values. The opaque coloring layer 42 may have an atomic percent of nitrogen atoms of 40% -50%, 30% -60%, 45% -55%, greater than 40%, greater than 30%, less than 50%, less than 70%, or other values.

The CrSiCN layer 80 may have an atomic percent of chromium atoms of 1% -5%, 1% -10%, 2% -8%, greater than 2%, greater than 1%, less than 5%, less than 10%, less than 20%, or other values. The CrSiCN layer 80 may have an atomic percent of 10% -20%, 5% -30%, 2% -40%, greater than 10%, greater than 5%, less than 20%, less than 30%, less than 40%, or other values. The CrSiCN layer 80 may have a nitrogen atom percentage of 30% -40%, 20% -50%, 25% -45%, greater than 30%, greater than 25%, less than 40%, less than 45%, less than 50%, or other values. The remaining atomic percent of CrSiCN layer 80 may be carbon atoms.

SiC layer 48 may have an atomic percent of silicon atoms of 20% -30%, 10% -40%, 12% -38%, greater than 12%, greater than 10%, less than 25%, less than 30%, less than 40%, or other values. The remaining atomic percent of SiC layer 80 may be carbon atoms. The coating 36 of fig. 10 may be light pink or gray pink. For example, at the location of peak coating thickness and at zero degrees of view relative to the normal axis of the coating, the coating 36 of fig. 10 may have L values of 60-80, 65-75, 68-72, 50-90, greater than 65, greater than 60, greater than 55, less than 75, less than 80, or other values, may have a value of a of 0-5, 0-10, -5-15, greater than 4, greater than 1, greater than 0, greater than-5, less than 10, less than 15, or other values, and may have b values of 0-5, 0-10, -5-15, greater than 3, greater than 1, greater than 0, greater than-5, less than 10, less than 15, or other values.

The device 10 may collect and/or use personally identifiable information. It is well known that the use of personally identifiable information should follow privacy policies and practices that are recognized as meeting or exceeding industry or government requirements for maintaining user privacy. In particular, personally identifiable information data should be managed and processed to minimize the risk of inadvertent or unauthorized access or use, and the nature of authorized use should be specified to the user.

According to one embodiment, an apparatus is provided that includes a conductive substrate and a coating on the conductive substrate and having a color, the coating including adhesion and transition layers, and a thin film interference filter on the adhesion and transition layers, the thin film interference filter including a diamond-like carbon (DLC) layer.

According to another embodiment, the DLC layer is the uppermost layer of the thin film interference filter.

According to another embodiment, the coating further comprises an opaque layer between the thin film interference filter and the adhesion and transition layer.

According to another embodiment, the thin film interference filter includes an additional layer between the DLC layer and the opaque layer.

According to another embodiment, the additional layer comprises chromium carbide (CrC).

According to another embodiment, the additional layer forms the bottommost layer of the thin film interference filter.

According to another embodiment, the thin film interference filter is a two layer thin film interference filter.

According to another embodiment, the coating further comprises an opaque layer between the thin film interference filter and the adhesion and transition layer.

According to another embodiment, the opaque layer comprises titanium carbonitride (TiCN) or titanium chromium carbonitride (TiCrCN).

According to another embodiment, the thin film interference filter is a three layer thin film interference filter, the DLC layer forms an uppermost layer of the three layer thin film interference filter, the three layer thin film interference filter includes a CrSiCN layer, and the three layer thin film interference filter includes a SiC layer between the CrSiCN layer and the DLC layer.

According to another embodiment, the coating has an L-value greater than 50 and a b-value greater than 5.

According to another embodiment, the conductive substrate comprises a sensor electrode.

According to one embodiment, there is provided an apparatus comprising a conductive substrate and a coating on the conductive substrate and having a color, the coating comprising: adhesion and transition layers; an opaque layer on the adhesion and transition layers; and a bilayer thin film interference filter on the opaque layer, the bilayer thin film interference filter comprising diamond-like carbon (DLC).

According to another embodiment, the dual layer thin film interference filter has a lowermost layer in contact with the uppermost layer and comprising chromium carbide (CrC).

According to another embodiment, the opaque layer comprises titanium carbonitride (TiCN) or titanium chromium carbonitride (TiCrCN).

According to another embodiment, the adhesion and transition layers include a chromium (Cr) seed layer and a transition layer on the Cr seed layer, the transition layer comprising chromium nitride (CrN) or chromium silicon nitride (CrSiN).

According to another embodiment, the apparatus includes a sensor configured to perform Electrocardiogram (ECG) measurements using a conductive structure, DLC having a ratio of sp ³ hybridized carbon to sp ² hybridized carbon exceeding a first threshold, and having a ratio of sp ³ hybridized carbon to hydrocarbon exceeding a second threshold.

According to one embodiment, an electronic device is provided that includes a housing, a display mounted to the housing, a sensor electrode on the housing, circuitry configured to collect sensor data using the sensor electrode, and a coating on the sensor electrode and having a color, the coating including a diamond-like carbon (DLC) layer forming a portion of a thin film interference filter.

According to another embodiment, the coating includes an adhesion and transition layer on the sensor electrode and an opaque layer on the adhesion and transition layer, the thin film interference filter has a lowermost layer in contact with the opaque layer, the DLC layer is an uppermost layer of the thin film interference filter, and the thin film interference filter has a SiC layer between the lowermost layer and the DLC layer.

According to another embodiment, the circuit is configured to collect Electrocardiogram (ECG) data using the sensor electrodes, and the DLC layer has a ratio of sp ³ hybridized carbon to sp ² hybridized carbon that exceeds a threshold.

The foregoing is merely illustrative and various modifications may be made to the embodiments. The foregoing embodiments may be implemented independently or may be implemented in any combination.

Claims (20)

1. An apparatus, the apparatus comprising:

a conductive substrate; and

A coating on the conductive substrate and having a color, the coating comprising:

adhesion and transition layers, and

A thin film interference filter on the adhesion and transition layer, wherein the thin film interference filter comprises a diamond-like carbon DLC layer.

2. The device of claim 1, wherein the DLC layer is an uppermost layer of the thin film interference filter.

3. The device of claim 2, wherein the coating further comprises an opaque layer between the thin film interference filter and the adhesion and transition layer.

4. The apparatus of claim 3, wherein the thin film interference filter comprises an additional layer between the DLC layer and the opaque layer.

5. The apparatus of claim 4, wherein the additional layer comprises chromium carbide CrC.

6. The apparatus of claim 5, wherein the additional layer forms a bottommost layer of the thin film interference filter.

7. The apparatus of claim 6, wherein the thin film interference filter is a dual layer thin film interference filter.

8. The device of claim 1, wherein the coating further comprises an opaque layer between the thin film interference filter and the adhesion and transition layer.

9. The device of claim 8, wherein the opaque layer comprises titanium carbonitride TiCN or titanium carbonitride chromium TiCrCN.

10. The apparatus of claim 1, wherein the thin film interference filter is a three-layer thin film interference filter, the DLC layer forms an uppermost layer of the three-layer thin film interference filter, the three-layer thin film interference filter comprises a CrSiCN layer, and the three-layer thin film interference filter comprises a SiC layer between the CrSiCN layer and the DLC layer.

11. The device of claim 1, wherein the coating has a L-value greater than 50 and a b-value greater than 5.

12. The device of claim 1, wherein the conductive substrate comprises a sensor electrode.

13. An apparatus, the apparatus comprising:

a conductive substrate; and

A coating on the conductive substrate and having a color, the coating comprising:

The adhesion and transition layer(s),

An opaque layer on the adhesion and transition layer, an

A bilayer thin film interference filter on the opaque layer and having an uppermost layer comprising diamond-like carbon DLC.

14. The apparatus of claim 13, wherein the dual layer thin film interference filter has a lowermost layer in contact with the uppermost layer and comprising chromium carbide CrC.

15. The device of claim 14, wherein the opaque layer comprises titanium carbonitride TiCN or titanium carbonitride chromium TiCrCN.

16. The device of claim 15, wherein the adhesion and transition layer comprises a chromium Cr seed layer and a transition layer on the Cr seed layer, the transition layer comprising chromium nitride CrN or chromium nitride silicon CrSiN.

17. The apparatus of claim 13, further comprising:

a sensor configured to perform electrocardiogram ECG measurements using the conductive structure, wherein the DLC has a ratio of sp ³ hybridized carbon to sp ² hybridized carbon exceeding a first threshold and has a ratio of sp ³ hybridized carbon to hydrocarbon exceeding a second threshold.

18. An electronic device, comprising:

A housing;

A display mounted to the housing;

a sensor electrode on the housing;

circuitry configured to collect sensor data using the sensor electrodes; and

A coating on the sensor electrode and having a color, wherein the coating comprises a diamond-like carbon DLC layer forming part of a thin film interference filter.

19. The electronic device of claim 18, the coating further comprising:

An adhesion and transition layer on the sensor electrode; and

An opaque layer on the adhesion and transition layer, wherein the thin film interference filter has a lowermost layer in contact with the opaque layer, the DLC layer is an uppermost layer of the thin film interference filter, and the thin film interference filter has a SiC layer between the lowermost layer and the DLC layer.

20. The electronic device defined in claim 18 wherein the circuitry is configured to collect electrocardiographic, ECG, data using the sensor electrodes and the DLC layer has a ratio of sp ³ -hybridized carbon to sp ² -hybridized carbon that exceeds a threshold.