CN117940832A - Display system with strain gauge circuit - Google Patents

Abstract

A head-mounted device (10) may have a head-mounted frame (26). The head-mounted frame may have an inner frame member (82), such as a metal frame member (metal frame structure). A frame structure, such as a polymeric frame structure (87), may be molded over the inner frame member (82) and may be provided with a lens opening. The head-mounted device may have a lens (54) with a waveguide mounted in the lens opening. The waveguide may be used to direct an image received from a projector (36) to an eyebox for viewing by a user. A strain gauge (76) circuit may be attached to a central portion (82M) of the inner frame member (82). During operation of the head mounted device (10), the strain gauge (76) circuit may measure deformation of the internal frame member (82) such that image distortion operations may be performed or such that other actions may be taken to correct image distortion caused by the measured deformation.

Description

Display system with strain gauge circuit

The present application claims priority from U.S. provisional patent application No. 63/285,419, filed on month 2 of 2021, and U.S. provisional patent application No. 63/246,603, filed on month 21 of 2021, which are hereby incorporated by reference in their entireties.

Technical Field

The present disclosure relates generally to electronic devices, and more particularly to electronic devices such as head-mounted devices.

Background

An electronic device, such as a head-mounted device, may have a display for displaying images. The display may be housed in a head mounted support structure.

Disclosure of Invention

A head-mounted device may have a head-mounted frame that serves as a housing for device components. The head-mounted frame may have an internal frame member, such as a metal frame member. The metal frame member (sometimes referred to as a metal frame structure, metal frame portion, metal inner frame, etc.) may have a top portion that extends laterally across the top of the head-mounted frame. The metal frame member may also have side portions extending downwardly from respective left and right end portions of the top portion of the metal frame member. The central region of the top portion of the metal frame member between the left end portion and the right end portion or other regions of the metal frame member may be provided with a flat surface and a rectangular cross-sectional profile. The central portion of the metal frame member may be thicker in one or more dimensions than the end portion of the top portion of the metal frame member or may be thinner in one or more dimensions than the end portion of the top portion of the metal frame member.

A frame structure, such as a polymeric frame structure, may be molded over the inner frame member and may be provided with a lens opening. The head-mounted device may have a lens with a waveguide mounted in the lens opening. The waveguide may be used to direct an image received from the projector to an eyebox for viewing by a user.

A strain gauge circuit (sometimes referred to as a strain gauge) may be attached to the top portion of the inner frame member in the central region or other region of the inner frame member. The strain gauge circuitry may measure deformation of the internal frame member during operation of the head mounted device. This allows image warping operations to be performed or other actions may be taken to correct for image distortion in the image caused by the measured distortion. The strain gauge circuitry may be embedded within the protective polymeric structure. The protective polymer structure may prevent polymer in the polymer frame structure from contacting the strain gauge circuitry when the polymer frame structure is molded onto the inner frame member.

Drawings

Fig. 1 is a schematic diagram of an exemplary electronic device, such as a head mounted display device, according to an embodiment.

Fig. 2 is a top view of an exemplary head mounted device according to an embodiment.

Fig. 3 is a rear perspective view of the underside of a headset according to an embodiment.

Fig. 4 is a diagram of an exemplary circuit for a head mounted device, according to an embodiment.

Fig. 5 is a diagram of an exemplary internal frame member for a head mounted device according to an embodiment.

Fig. 6 is a diagram of the exemplary frame member of fig. 5 to which the exemplary circuit of fig. 4 has been mounted, according to an embodiment.

Fig. 7 is an illustration of a portion of a head mounted device according to an embodiment.

Fig. 8 is a perspective view of an exemplary frame member for a head mounted device according to an embodiment.

Fig. 9 is a cross-sectional side view of a central portion of the exemplary frame member of fig. 8 to which a strain gauge has been mounted, according to an embodiment.

Fig. 10 is a perspective view of an exemplary strain gauge circuit for a head mounted device according to an embodiment.

Fig. 11 is a cross-sectional side view of a portion of an exemplary head mounted support structure according to an embodiment.

Detailed Description

Electronic devices, such as head-mounted devices, may include displays and other components for presenting content to a user. The head-mounted device may have a head-mounted support structure that allows the head-mounted device to be worn on the head of a user. The head-mounted support structure may support optical components such as a display for displaying visual content and a front-facing camera for capturing real world images. In an exemplary configuration, optical components such as waveguides and the like may be used to provide images from a display projector to an eyebox for viewing by a user.

The head-mounted device may have a sensor. For example, strain gauge sensors may be used to monitor potential deformations (e.g., torsion, bending, etc.) of the support structure. Deformation of the support structure (e.g., deformation of the eyeglass frame members or other head-mounted support structures due to excessive forces, such as forces from a drop event) can potentially result in misalignment of the optical components and image distortion. By using strain gauge sensor circuitry to monitor frame bending and other support structure deformations, corrective action can be taken to prevent unwanted image distortion. For example, digital image warping operations may be performed on digital image data provided to the projector and/or other actions may be taken to compensate for distortion. In this way, the headset can compensate for the measured support structure deformation.

A schematic diagram of an exemplary system that may include a head mounted device is shown in fig. 1. As shown in fig. 1, system 8 may include one or more electronic devices, such as electronic device 10. The electronic devices of system 8 may include computers, cellular telephones, head-mounted devices, wristwatch devices, and other electronic devices. The configuration in which the electronic device 10 is a head mounted device is sometimes described herein as an example.

As shown in fig. 1, an electronic device, such as electronic device 10, may have a control circuit 12. Control circuit 12 may include storage and processing circuitry for controlling the operation of device 10. The circuit 12 may include a storage device, such as a hard drive storage device, a non-volatile memory (e.g., an electrically programmable read-only memory configured to form a solid state drive), a volatile memory (e.g., static or dynamic random access memory), and so forth. The processing circuitry in control circuit 12 may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio chips, graphics processing units, application specific integrated circuits, and other integrated circuits. The software codes may be stored on a memory device in the circuit 12 and run on a processing circuit in the circuit 12 to implement control operations for the device 10 (e.g., data acquisition operations, operations involving adjusting components of the device 10 using control signals, etc.). The control circuit 12 may include wired and wireless communication circuits. The control circuit 12 may include radio frequency transceiver circuitry, such as cellular telephone transceiver circuitry, wireless local area network transceiver circuitry (e.g.,Circuitry), millimeter-wave transceiver circuitry, and/or other wireless communication circuitry.

During operation, the communication circuitry of the devices in system 8 (e.g., the communication circuitry of control circuitry 12 of device 10) may be used to support communication between electronic devices. For example, one electronic device may transmit video data, audio data, and/or other data to another electronic device in system 8. The electronic devices in system 8 may use wired and/or wireless communication circuitry to communicate over one or more communication networks (e.g., the internet, a local area network, etc.). The communication circuitry may be used to allow the device 10 to receive data from external equipment (e.g., tethered computers, portable devices such as handheld or laptop computers, online computing equipment such as remote servers or other remote computing equipment, or other electrical equipment) and/or to provide data to external equipment.

The device 10 may include an input-output device 22. The input-output device 22 may be used to allow a user to provide user input to the device 10. The input-output device 22 may also be used to gather information about the environment in which the device 10 is operating. Output components in device 22 may allow device 10 to provide output to a user and may be used to communicate with external electrical equipment.

As shown in FIG. 1, the input-output device 22 may include one or more displays such as display 14. In some configurations, device 10 includes left and right display devices (e.g., left and right components, such as left and right projectors based on scanning mirror display devices, liquid crystal on silicon display devices, digital mirror devices, or other reflective display devices, left and right display panels based on light emitting diode pixel arrays (e.g., organic light emitting display panels, or display devices based on pixel arrays formed from crystalline semiconductor light emitting diode dies), liquid crystal display panels, and/or other left and right display devices that provide images to left and right eye regions, respectively, for viewing by left and right eyes of a user).

The display 14 is used to display visual content for a user of the device 10. The content presented on the display 14 may include virtual objects and other content provided to the display 14 by the control circuitry 12. This virtual content may sometimes be referred to as computer-generated content. The computer-generated content may be displayed in the absence of real-world content or may be combined with real-world content. For example, an optical coupling system may be used to allow computer-generated content to be optically overlaid on top of a real-world image. In particular, device 10 may have a see-through display system that provides a computer-generated image to a user through a beam splitter, prism, holographic coupler, diffraction grating, or other optical coupler (e.g., an output coupler on a waveguide for providing the computer-generated image to the user) while allowing the user to view real-world objects through the optical coupler and other transparent structures (e.g., transparent waveguide structures, vision correction lenses, and/or other lenses, etc.).

The input-output circuit 22 may include the sensor 16. The sensor 16 may include, for example, a three-dimensional sensor (e.g., a three-dimensional image sensor, such as a structured light sensor that emits a light beam and that uses a two-dimensional digital image sensor to collect image data for a three-dimensional image from a light spot generated when the target is illuminated by the light beam, a binocular three-dimensional image sensor that uses two or more cameras in a binocular imaging arrangement to collect a three-dimensional image, a three-dimensional laser radar (light detection and ranging) sensor, a three-dimensional radio frequency sensor, or other sensor that collects three-dimensional image data), a camera (e.g., an infrared digital image sensor and/or a visible digital image sensor), a gaze tracking sensor (e.g., a gaze tracking system based on an image sensor and also based on a light source if desired, the light source emits one or more light beams that are tracked after reflection from the user's eyes using an image sensor), touch sensors, capacitive proximity sensors, light-based (optical) proximity sensors, other proximity sensors, force sensors, sensors such as switch-based contact sensors, gas sensors, pressure sensors, humidity sensors, magnetic sensors, audio sensors (microphones), ambient light sensors, microphones for gathering voice commands and other audio inputs, sensors configured to gather information about motion, position and/or orientation (e.g., accelerometers, gyroscopes, compasses, and/or inertial measurement units comprising all or a subset of one or both of these sensors), strain gauge sensors and/or other sensors.

User inputs and other information may be collected using sensors and other input devices in the input-output device 22. If desired, the input-output device 22 may include other devices 24, such as haptic output devices (e.g., vibrating components), light emitting diodes and other light sources, speakers such as ear speakers for producing audio output, circuitry for receiving wireless power, circuitry for wirelessly transmitting power to other devices, batteries and other energy storage devices (e.g., capacitors), joysticks, buttons, and/or other components.

The electronic device 10 may have a housing structure, as shown by the exemplary support structure 26 of fig. 1. In configurations where the electronic device 10 is a head-mounted device (e.g., a pair of glasses, goggles, a helmet, a hat, etc.), the support structure 26 may include a head-mounted support structure (e.g., a helmet shell, a headband, arms or temples in a pair of glasses, a goggle shell structure, and/or other head-mounted structures). The head-mounted support structure may be configured to be worn on the head of a user during operation of the device 10, and may support the display 14, the sensors 16, other components 24, other input-output devices 22, and the control circuitry 12.

Fig. 2 is a top view of the electronic device 10 in an exemplary configuration in which the electronic device 10 is a head-mounted device. As shown in fig. 2, the electronic device 10 may include a head-mounted support structure 26 to house components of the device 10 and support the device 10 on the head of a user. The support structure 26 may include, for example, structures forming the housing walls, as well as other structures at the front of the device 10 (sometimes referred to as frames, lens support frames, eyeglass frames, etc.). In particular, the support structure 26 may include a support structure 26-2 at the front of the device 10 that forms a spectacle frame structure such as a nose bridge, a frame portion that supports left and right lenses with embedded waveguides, and/or other housing structures. The support structure 26 may also include additional structures, such as straps, eyeglass arms, or other auxiliary support structures (e.g., support structure 26-1) that help hold the frame and components therein on the face of the user such that the eyes of the user are located within the eyebox 30. If desired, the support structure 26 may include a hinge, such as hinge 26H. The support structure 26-1 (which may sometimes be referred to as an arm or temple) may be coupled to the support structure 26-2 (which may sometimes be referred to as an eyeglass frame, a lens frame, or a frame) using a hinge 26H (e.g., such that the arm of the device 10 may fold parallel to the frame at the front of the device 10 when not in use).

During operation of the device 10, an image is presented to the user's eye in the eyebox 30. The eyebox 30 includes a left eyebox that receives a left image and a right eyebox that receives a right image. The device 10 may include a left display system with a left display 14 presenting a left image to the left eye-ward region and a right display system with a right display 14 presenting a right image to the right eye-ward region. In an exemplary configuration, each display system may have an optical combiner component that facilitates combining a display image (e.g., computer-generated image 32 of fig. 2, sometimes referred to as a virtual image) with real-world image light (e.g., light from a real-world object such as object 34 of fig. 2). The optical combiner assembly may include an optical coupler, a waveguide, and/or other components.

As an example, each display system may have a corresponding projector 36, a waveguide 38, and an optical coupler (e.g., a prism and/or other optical coupling element) for coupling an image from the projector into the waveguide from the projector. The output coupler on each waveguide may be used to couple an image exiting the waveguide toward the respective eyebox after the waveguide has directed the image to a position overlapping the eyebox.

In the illustrative configuration of fig. 2, left projector 36 may generate a left image and right projector 36 may generate a right image. Left and right waveguides 38 at the front of device 10 may be provided with left and right optical input couplers 38A that receive left and right images, respectively, and couple those images into the left and right waveguides. Waveguide 38 then transmits the received image laterally to the center of device 10 in accordance with the principles of total internal reflection. The left and right images (e.g., computer-generated image 32) are coupled out of the waveguide toward the eyebox 30 using an output coupler 38B (e.g., a grating, holographic output coupler, or other suitable output coupler). The output coupler 38B is transparent so that a user may view real world objects, such as object 34, from the eyebox 30.

Fig. 3 is a simplified rear perspective view of the head mounted device 10 taken from the underside of the device 10. As shown in fig. 3, the support structure 26-1 may be configured to form left and right arms (sometimes referred to as temples or frame supports). The arms of the device 10 may be coupled to the hinge 26H. When the device 10 is worn on the user's head, the left and right arms of the device 10 may extend along the left and right sides of the user's head, respectively. Structure 26-2 may include a front frame portion, such as top frame portion 50 (sometimes referred to as a top frame member, top frame structure, or upper frame edge support structure), that extends laterally across the top of device 10 from left to right when device 10 is worn by a user. The structure 26-2 may also include left and right frame portions 58 (sometimes referred to as frame edge members or edge support structures) that extend downwardly from the top frame portion 50 when the device 10 is worn by a user. At the center of the device 10, the support structure 26-2 may form a nose bridge portion 52 (e.g., when the device 10 is worn on the head of a user, the eyeglass frame formed by the structure 26-2 may include nose bridge structures extending downward from top frame members (top frame structures, top frame portions, etc.) 50 on the left and right sides of the user's nose). The portion 60 of the structure 26-2 (which may sometimes be referred to as a eyeglass frame rearward extension, a side housing extension, an end piece, or a temple) may extend rearward from the eyeglass frame at the front of the apparatus 10, formed by the portion 50, the nose bridge portion 52, and the side frame portion 58, to the hinge 26H.

The support structure 26-2 may be configured to support left and right eyeglass lenses 54. An optional lower frame portion 56 may extend along the lower edge of each lens 54 to help support the bottom of the lens 54. The optic 54 may comprise an embedded waveguide for laterally conveying an image from the display projector to a location overlapping the eyebox 30 (fig. 2), may comprise external and internal optical elements such as protective transparent layers, vision correction optics, fixed and/or tunable optics to help establish a desired virtual image distance for the virtual image 32, and/or other optical structures (e.g., light modulator layers, polarizer structures, etc.). In an exemplary configuration, the device 10 has: a left eyeglass lens having a left waveguide and an output coupler (and, if desired, additional structures such as one or more lens elements with associated optical power); and a right eyeglass lens having a right waveguide and a right output coupler (and, if desired, additional structures such as one or more lens elements with associated non-zero optical power). As an example, the left and right waveguides may each be sandwiched between an outer transparent optical structure and an inner transparent optical structure (e.g., a lens element, a protective transparent layer, etc.). During operation, projector 36 (fig. 2) may provide left and right images to the left and right waveguides, respectively. The left and right waveguides may direct the left and right images, respectively, to portions of the lens 54 having output couplers that overlap the eyebox 30, where the output couplers may direct the left and right images to corresponding left and right eyeboxes for viewing by the left and right eyes of the user.

During use of the device 10, the device 10 may experience undesirably large forces (e.g., during a drop event). These excessive forces may cause the structure 26 to bend or otherwise deform, which may result in misalignment between the optical components of the device 10. Consider, for example, the case where nose bridge portion 52 of structure 26-2 is curved about the Y-axis of fig. 3. In this case, the left and right images provided to the left and right eye-ward will diverge (or converge) and will not be satisfactorily aligned with the eye-ward 30. As another example, consider a case in which nose bridge portion 52 is twisted about the X-axis. In this case, the left image would be provided above its desired location in the left eye region and the right image would be provided below its desired location in the right eye region (as an example). The deformation of structure 26 may also cause the waveguides in device 10 to become misaligned relative to the projector in device 10. As these exemplary cases demonstrate, deformation of the structure 26 due to undesirable excessive forces may lead to misalignment and potential for image distortion (image shifting, keystone, etc.). These image distortion effects can be digitally compensated by applying compensation image distortion to the image data provided to the left projector and the right projector.

Sensor measurements (e.g., using sensor 16) may be used to measure deformations of structure 26 and/or other sources of optical system misalignment so that control circuit 12 may take corrective action. As an example, strain gauge circuitry mounted in nose bridge portion 52 and/or other areas of the frame may be used to measure frame deformation. The strain gauge circuitry may include one or more strain gauges (e.g., one or more sets of strain gauge sensor electrodes that exhibit a measurable change in resistance when bent). The strain gauge circuitry may measure support structure deformations (e.g., frame torsion, frame bending, etc.). In the illustrative case, which may be described herein at times as an example, the frame of the apparatus 10 may have an internal support member, such as a metal frame member with strain gauges attached. Bending and/or torsion may be measured about any suitable dimension (e.g., about axis X, axis Y, and/or axis Z).

Fig. 4 shows exemplary circuitry 72, 76, and 80 for forming circuitry of device 10 (e.g., control circuitry 12, input-output device 22, etc.). The circuitry 76 may include strain gauge circuitry (sometimes referred to as strain gauges), such as strain gauges (strain gauge sensors) formed from strain gauge traces on a flexible printed circuit, and associated strain gauge support circuitry, such as amplifier circuitry (e.g., one or more amplifiers) and analog-to-digital converter circuitry (e.g., one or more analog-to-digital converters), that measure strain-induced resistance changes in the strain gauge traces. Strain gauges may be coupled to a frame member (such as a metal frame member) to monitor deformation of the frame member. Circuitry 72 and circuitry 80 may include integrated circuits and other components for forming control circuit 12, display 14 (e.g., projector 36 of fig. 2), other input output devices 22 such as speakers, batteries, and the like. Signal paths 74 and 78 (e.g., signal paths formed by wires in a cable, metal traces on a printed circuit, etc.) may be used to electrically connect circuit 72, circuit 76, and circuit 80. In this way, power may be routed from the battery in the device 10 to integrated circuits, sensors, displays, and other power supply components, data from the sensors may be routed to control circuitry, control signals and other outputs may be routed from the control circuitry to adjustable components (e.g., displays, actuators, speakers, etc.), and so forth. The signals carried by paths 74 and 78 may include analog signals and/or digital signals.

The structure 26 may be configured to form a head-mounted frame having a lens opening that receives the left and right lenses in alignment with the eyes of the user. To provide the desired strength and rigidity to the device 10, the structure 26 (e.g., a head-mounted frame) may include an outer portion, such as an outer polymer structure (outer polymer portion) that covers one or more inner support portions. By way of example, the structure 26 may include an internal frame member, such as the frame member 82 of fig. 5 (sometimes referred to as an internal frame, eyeglass frame member, internal frame member, stiffening member, etc.). The frame member 82 may be formed of a rigid material, such as a metal, carbon fiber composite, or other fiber composite (e.g., a polymer containing hardened fibers of embedded glass, carbon, or other fiber material), and may include a rigid polymer, glass, ceramic, or the like. In the exemplary configuration, which may be described herein at times as examples, the frame member 82 may be formed of metal (e.g., aluminum, titanium, steel, magnesium, and/or other elemental metals and/or metal alloys), and may sometimes be referred to as a metal frame, a metal member, or a metal frame member. The frame member 82 may be machined (e.g., using a computer numerical control tool or other suitable forming equipment) and/or may be otherwise formed into a desired final configuration. In the example of fig. 5, the frame member 82 has a top portion (e.g., an elongated horizontally extending bar that laterally spans the width of the frame of the device 10 as described in connection with the top portion 50 of fig. 3). The frame member 82 also has side portions (e.g., inner support member portions for forming the side portions 58 of fig. 3). If desired, the frame member 82 may include a central portion 82M having one or more planar surfaces. As an example, the portion 82M may have a rectangular cross-sectional shape and a thickness that is greater in at least one dimension than a corresponding thickness of an adjacent end portion of the top portion of the frame member 82. When assembled into the device 10, the central portion 82M may be located in the nose bridge portion 52 of the structure 26.

Fig. 6 is a front view of the frame member 82 after the circuit 70 of fig. 4 is attached. As shown in fig. 6, member 82 may have channels or other structures that receive cables or other signal lines of paths 74 and 78. The strain gauge of circuit 76 may be mounted on portion 82M. A protective polymer 85 (e.g., epoxy or other polymer) may be molded over the circuit 76. The presence of the polymer 85 may protect the strain gauge circuitry of the circuitry 76 from exposure to elevated temperatures during subsequent polymer injection molding operations used to form the outer portion of the frame.

As shown in the exemplary portion of structure 26 of fig. 7 (e.g., the head-mounted frame of device 10), a polymer injection molding operation may be used to form the outer polymer portion of the frame (e.g., polymer frame structure 87 may be molded over frame member 82 and over protective polymer 85 of fig. 6 to form a eyeglass frame having a desired appearance). The frame (e.g., the polymer of structure 87) may be configured to form a lens opening. This allows eyeglass lenses, such as the exemplary lens 88 of fig. 7, to be mounted in the frame structure 87 (e.g., the left and right lenses 88 may be supported by the head-mounted structure 26 formed by the frame 82 after the polymer frame structure 87 is overmolded, as described in connection with the lenses 54 of fig. 3). During operation of the device 10, the projector may provide left and right images that are guided by the waveguides in the lens 54 to respective left and right eye-ward regions for viewing by a user.

To provide a satisfactory support surface for a strain gauge mounted to the middle of the member 82, the central portion 82M of the member 82 may be larger in cross-sectional dimension (e.g., thicker in one or two orthogonal dimensions) than the peripheral portion of the member 82, as shown in the perspective view of the exemplary member 82 of fig. 8. The strain sensitivity can be improved by reducing the thickness of the intermediate portion, if desired. In this type of arrangement, the central portion 82M of the member 82 may be smaller in cross-sectional dimension (e.g., thinner in one or two orthogonal dimensions) than the peripheral portion of the member 82. As shown in fig. 8, by way of example, the member 82 may have a downwardly oriented C-shape with an elongated top portion 82T and left and right side portions 82L and 82R, respectively, extending downwardly from the outer ends of the portion 82T. The portion 82M may have planar surfaces such as a planar rear surface 84, an opposing planar front surface 88, and an upwardly facing top surface 86 extending between the rear surface 84 and the front surface 88.

If desired, one or more strain gauges may be mounted to the peripheral portion of the member 82 instead of or in addition to the mounting of the strain gauges to the central portion 82M. For example, the left end portion and/or the right end portion of the member 82 may have a plurality of planar surfaces (e.g., surfaces such as the exemplary planar surfaces of portion 82M) configured to receive strain gauge sensor traces. As an example, the mounting location of the left strain gauge may be located to the left of both the right and left lenses, while as an example, the mounting location of the right strain gauge may be located to the right of both the right and left lenses. In this type of arrangement, strain measurement sensitivity may be enhanced by locally thinning the left and/or right end portions of the member 82 below the strain gauge. The use of the configuration of the member 82 with the strain gauge mounted in the central portion 82M is illustrative.

The strain gauges of the circuit 76 (whether mounted to the central portion and/or the peripheral end portion of the member 82) may be formed from conductive electrical traces such as meandering metal traces on a substrate such as a flexible printed circuit substrate. Fig. 9 is a cross-sectional view of portion 82M of member 82 of fig. 8 taken along line 90 and viewed along direction 92. As shown in fig. 9, the strain gauge of circuit 76 (fig. 4) may be formed from strain gauge traces and associated support circuitry on flexible printed circuit 94. The support circuits may include one or more integrated circuits, such as integrated circuit 98 (e.g., amplifier circuits, analog-to-digital converter circuits, etc.). An integrated circuit such as circuit 98 may be mounted directly on flexible printed circuit 94 or, as shown in fig. 9, may be mounted to a substrate such as substrate 106 (e.g., a rigid printed circuit) mounted to flexible printed circuit 94. A system in package arrangement of the circuit 98 may also be used if desired. Solder, conductive adhesive, connectors, and/or other conductive structures may be utilized to form conductive connections between signal lines in circuit 94 and circuit 106. Signal lines, such as lines associated with paths 74 and 78 of fig. 4, may be attached to the circuit of fig. 9 using connections (e.g., pad connections, solder, connectors, etc.) such as connection 100.

As shown in the example of fig. 9, the printed circuit 94 may be at least partially wrapped around the member 82M. For example, a first planar portion of the printed circuit 94 may be attached to the inner planar surface 84, a second planar portion of the printed circuit 94 may be attached to the outer planar portion 88, and a third planar portion of the printed circuit 94 extending between the first and second portions is attached to the top planar surface 86. As shown in fig. 10, the portion of printed circuit 94 that overlaps surface 84 may include a first set of strain gauge traces 102, and the portion of printed circuit 94 that overlaps surface 86 (which has a surface normal that is orthogonal to the surface normal of surface 84) may include a second set of strain gauge traces 104. For example, trace 102 and trace 104 may each contain a set of separate patches of strain gauge traces coupled to respective arms of a Wheatstone bridge circuit or other strain gauge circuit. Using trace 102 and trace 104, bending about orthogonal axes Y and Z may be measured, torsional deformation (e.g., torsion of member 82 about the X-axis of fig. 10) may be measured, and/or other deformations of member 82, and thus head-mounted support structure 26, may be measured. Control circuit 12 may process these measurements of the deformation of the support structure of device 10 and may take appropriate corrective action (e.g., by warping the image data provided to the left and right display projectors to compensate for any measured deformation, by adjusting the optical component alignment locator, etc.). In the example of fig. 9, the first set of strain gauge traces and the second set of strain gauge traces 102 are formed on separate portions of the same printed circuit 94 (e.g., a printed circuit wrapped around the member 82M). If desired, a separate strain gauge substrate may be used (e.g., a first printed circuit may contain a first set of strain gauge traces, a second printed circuit may contain a second set of strain gauge traces, and each of the two sets of strain gauge traces may be mounted on a respective planar surface of the member 82M). In this way, a first portion of the strain gauge may be formed by a first strain gauge printed circuit on a first planar surface of the central portion of the metal frame member and a second portion of the strain gauge may be formed by a second strain gauge printed circuit on a second planar surface of the central portion of the metal frame member. The first and second planar surfaces may have respective first and second surface normals that are perpendicular to each other.

Fig. 11 is a cross-sectional side view of a top portion of a head-mounted frame formed from structure 26 (e.g., a cross-sectional side view of member 82 taken along line 90 of fig. 8 after the polymer frame structure is overmolded on top of frame member 82). As shown in fig. 11, the strain gauge formed by the flexible printed circuit substrate 94 and the circuitry 98 on the printed circuit 106 may be embedded within a protective internal structure (such as a structure formed by the protective polymer 85). Additional polymers may be formed around polymer 85. For example, an outer frame structure such as polymer structure 87 (see, e.g., fig. 7) may be injection molded (injection molded using one or more polymer injection molding) around the exposed portions of polymer 85 and frame member 82. The presence of the polymer 85 may prevent the polymer structure 87 from contacting the strain gauge circuitry (circuitry 76) and may thereby protect the strain gauge from the elevated injection molding temperatures involved in forming the structure 87. The structure 87 can be configured to form an eyeglass frame having a desired shape and appearance (e.g., a shape for supporting a lens such as the lens 88 of fig. 7, a desired shape for forming the nose bridge portion 52 of the structure 26, etc.). Circuitry 72 and circuitry 80 may be mounted in an interior cavity of structure 26 (e.g., a cavity in portion 60 of molded polymer structure 87) or elsewhere in structure 26.

In some embodiments, the sensor may collect personal user information. To ensure that the privacy of the user is preserved, all applicable privacy rules should be met or exceeded, and best practices for handling personal user information should be followed. Users may be allowed to control the use of their personal information according to their preferences.

According to one embodiment, there is provided a head-mounted device comprising: a head-mounted frame having a metal frame extending laterally across the head-mounted frame; a left projector and a right projector configured to output respective left and right images; left and right lenses in the head-mounted frame; and a strain gauge having a flexible printed circuit coupled to the metal frame between the left and right lenses, the flexible printed circuit having a first portion with a first strain gauge trace and a second portion with a second strain gauge trace.

According to another embodiment, the metal frame has a first planar surface and a second planar surface, and the first portion is attached to the first planar surface and the second portion is attached to the second planar surface.

According to another embodiment, the first planar surface and the second planar surface have respective surface normals orthogonal to each other.

According to another embodiment, the first planar surface extends across an upwardly facing portion of the metal frame and the second planar surface extends across a horizontally facing portion of the metal frame.

According to another embodiment, the metal frame comprises a C-shaped metal frame having a top portion extending across the head-mounted frame over the left and right lenses and having left and right side portions extending downwardly from respective left and right ends of the top portion, and the strain gauge is attached to the top portion.

According to another embodiment, the head-mounted frame comprises a polymer covering at least a portion of the metal frame.

According to another embodiment, the top portion comprises a metal rod having a central portion with a rectangular cross-sectional profile, and the strain gauge is attached to the central portion.

According to another embodiment, the central portion has a first planar portion and a second planar portion, and the flexible printed circuit is bent around the central portion and attached to the first planar portion and the second planar portion.

According to another embodiment, the first planar portion and the second planar portion are oriented perpendicular to each other.

According to another embodiment, the metal bar has a first end portion and a second end portion, the central portion is between the first end portion and the second end portion, and the central portion is thicker than the first end portion and the second end portion in at least one cross-sectional dimension.

According to another embodiment, the metal bar has a first end portion and a second end portion, the central portion is between the first end portion and the second end portion, and the central portion is thinner than the first end portion and the second end portion in at least one cross-sectional dimension.

According to another embodiment, the metal frame comprises a metal bar, and the flexible printed circuit is attached to the metal bar and configured to measure deformation of the metal bar.

According to another embodiment, a strain gauge is configured to measure deformation of a metal frame, the headset frame comprising a first polymer portion covering the strain gauge and a second polymer portion molded over at least a portion of the metal frame and over the first polymer portion.

According to another embodiment, the flexible printed circuit is embedded in the first polymer portion, and the first polymer portion prevents contact between the flexible printed circuit and the second polymer portion.

According to another embodiment, the first polymeric portion is embedded within the second polymeric portion, and the second polymeric portion has lens openings configured to receive the left lens and the right lens, respectively.

According to another embodiment, the left and right lenses include respective left and right waveguides that guide the left and right images.

According to one embodiment, there is provided a head-mounted device comprising: a metal frame; a strain gauge having a flexible printed circuit with a strain gauge trace, the flexible printed circuit being at least partially wrapped around a central portion of the metal frame; a polymer attached to the metal frame, the polymer having a lens opening; and a lens in the lens opening.

According to another embodiment, the head mounted device comprises at least one projector providing an image, at least one of the lenses having a waveguide guiding the image.

According to another embodiment, a strain gauge includes an amplifier and an analog-to-digital converter mounted on a substrate attached to a flexible printed circuit.

According to one embodiment, there is provided a head-mounted device comprising: a metal frame having a first planar surface and a second planar surface, the first planar surface and the second planar surface having respective first surface normals and second surface normals that are perpendicular to each other; a strain gauge having a first printed circuit with a first strain gauge trace mounted on a first planar surface and a second printed circuit with a second strain gauge trace mounted on a second planar surface; a polymer attached to the metal frame, the polymer having a lens opening; and a lens in the lens opening.

According to another embodiment, the head mounted device comprises at least one projector providing an image, at least one of the lenses having a waveguide guiding the image.

According to another embodiment, a strain gauge includes an amplifier and an analog-to-digital converter.

According to one embodiment, there is provided a head-mounted device comprising: a head-mounted frame having an elongated metal inner frame extending transversely across the head-mounted frame and having a polymer frame portion covering the elongated metal inner frame, the polymer frame portion having a lens opening; a lens in the lens opening; and a strain gauge having a flexible substrate attached to the elongated metal inner frame.

According to another embodiment, the elongated metal inner frame has a central portion with at least a first planar surface and a second planar surface oriented in different directions, and the flexible substrate is attached to the first planar surface and the second planar surface.

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 (24)

1. A head-mounted device, comprising:

A headset frame having a metal frame extending laterally across the headset frame;

A left projector and a right projector configured to output respective left and right images;

Left and right lenses in the head-mounted frame; and

A strain gauge having a flexible printed circuit coupled to the metal frame between the left lens and the right lens, the flexible printed circuit having a first portion with a first strain gauge trace and a second portion with a second strain gauge trace.

2. The headset of claim 1, wherein the metal frame has a first planar surface and a second planar surface, and wherein the first portion is attached to the first planar surface and the second portion is attached to the second planar surface.

3. The headset of claim 2, wherein the first planar surface and the second planar surface have respective surface normals that are orthogonal to each other.

4. The headset of claim 3, wherein the first planar surface extends across an upwardly facing portion of the metal frame, and wherein the second planar surface extends across a horizontally facing portion of the metal frame.

5. The headset of claim 1, wherein the metal frame comprises a C-shaped metal frame having a top portion extending across the headset above the left and right lenses and having left and right side portions extending downwardly from respective left and right ends of the top portion, and wherein the strain gauge is attached to the top portion.

6. The headset of claim 5, wherein the headset frame comprises a polymer covering at least a portion of the metal frame.

7. The headset of claim 6, wherein the top portion comprises a metal rod having a central portion with a rectangular cross-sectional profile, and wherein the strain gauge is attached to the central portion.

8. The head mounted device of claim 7, wherein the central portion has a first planar portion and a second planar portion, and wherein the flexible printed circuit is bent around the central portion and attached to the first planar portion and the second planar portion.

9. The headset of claim 8, wherein the first planar portion and the second planar portion are oriented perpendicular to each other.

10. The headset of claim 9, wherein the metal bar has a first end portion and a second end portion, wherein the central portion is between the first end portion and the second end portion, and wherein the central portion is thicker in at least one cross-sectional dimension than the first end portion and the second end portion.

11. The headset of claim 9, wherein the metal bar has a first end portion and a second end portion, wherein the central portion is between the first end portion and the second end portion, and wherein the central portion is thinner than the first end portion and the second end portion in at least one cross-sectional dimension.

12. The headset of claim 1, wherein the metal frame comprises a metal bar, and wherein the flexible printed circuit is attached to the metal bar and configured to measure deformation of the metal bar.

13. The headset of claim 1, wherein the strain gauge is configured to measure deformation of the metal frame, the headset further comprising a first polymer portion covering the strain gauge and a second polymer portion molded over at least a portion of the metal frame and over the first polymer portion.

14. The head mounted device of claim 13, wherein the flexible printed circuit is embedded in the first polymer portion, and wherein the first polymer portion prevents contact between the flexible printed circuit and the second polymer portion.

15. The head mounted device of claim 14, wherein the first polymer portion is embedded within the second polymer portion, and wherein the second polymer portion has a lens opening configured to receive the left lens and the right lens, respectively.

16. The headset of claim 15, wherein the left lens and the right lens comprise respective left and right waveguides that guide the left and right images.

17. A head-mounted device, comprising:

A metal frame;

A strain gauge having a flexible printed circuit with a strain gauge trace, wherein the flexible printed circuit is at least partially wrapped around a central portion of the metal frame;

a polymer attached to the metal frame, wherein the polymer has a lens opening; and

A lens in the lens opening.

18. The headset of claim 17, further comprising at least one projector that provides an image, wherein at least one of the lenses has a waveguide that guides the image.

19. The headset of claim 17, wherein the strain gauge comprises an amplifier and an analog-to-digital converter mounted on a substrate attached to the flexible printed circuit.

20. A head-mounted device, comprising:

A metal frame having a first planar surface and a second planar surface, the first planar surface and the second planar surface having respective first surface normals and second surface normals that are perpendicular to each other;

A strain gauge having a first printed circuit with a first strain gauge trace mounted on the first planar surface and a second printed circuit with a second strain gauge trace mounted on the second planar surface;

a polymer attached to the metal frame, wherein the polymer has a lens opening; and

A lens in the lens opening.

21. The headset of claim 20, further comprising at least one projector that provides an image, wherein at least one of the lenses has a waveguide that guides the image.

22. The headset of claim 20, wherein the strain gauge comprises an amplifier and an analog-to-digital converter.

23. A head-mounted device, comprising:

A head-mounted frame having an elongated metal inner frame extending transversely across the head-mounted frame and having a polymer frame portion covering the elongated metal inner frame, wherein the polymer frame portion has a lens opening;

a lens in the lens opening; and

A strain gauge having a flexible substrate attached to the elongated metal inner frame.

24. The headset of claim 23, wherein the elongated metal inner frame has a central portion with at least first and second planar surfaces oriented in different directions, and wherein the flexible substrate is attached to the first and second planar surfaces.