Technical Field

The present systems, devices, and methods generally relate to interacting with content displayed on head-mounted displays and particularly relate to a multi-input interface that combines eye tracking with a wireless portable interface device.

BACKGROUND Description of the Related Art WEARABLE ELECTRONIC DEVICES

Electronic devices are commonplace throughout most of the world today. Advancements in integrated circuit technology have enabled the development of electronic devices that are sufficiently small and lightweight to be carried by the user. Such "portable" electronic devices may include on- board power supplies (such as batteries or other power storage systems) and may be "wireless" (i.e., designed to operate without any wire-connections to other, non-portable electronic systems); however, a small and lightweight electronic device may still be considered portable even if it includes a wire- connection to a non-portable electronic system. For example, a microphone may be considered a portable electronic device whether it is operated wirelessly or through a wire-connection.

The convenience afforded by the portability of electronic devices has fostered a huge industry. Smartphones, audio players, laptop computers, tablet computers, and ebook readers are all examples of portable electronic devices. However, the convenience of being able to carry a portable electronic device has also introduced the inconvenience of having one's hand(s) encumbered by the device itself. This problem is addressed by making an electronic device not only portable, but wearable.

A wearable electronic device is any portable electronic device that a user can carry without physically grasping, clutching, or otherwise holding onto the device with their hands. For example, a wearable electronic device may be attached or coupled to the user by a strap or straps, a band or bands, a clip or clips, an adhesive, a pin and clasp, an article of clothing, tension or elastic support, an interference fit, an ergonomic form, etc. Examples of wearable electronic devices include digital wristwatches, electronic armbands, electronic rings, electronic ankle-bracelets or "anklets," head-mounted electronic display units, hearing aids, and so on.

Because they are worn on the body of the user, visible to others, and generally present for long periods of time, form factor (i.e., size, geometry, and appearance) is a major design consideration in wearable electronic devices.

HEAD-MOUNTED DISPLAYS

A head-mounted display is a form of wearable electronic device that is worn on the user's head and, when so worn, positions a display in the user's field of view. This enables the user to see content displayed on the display at all times, without using their hands to hold the display and regardless of the direction in which the user's head is facing. A wearable head-mounted display may completely occlude the external environment from the user's view, in which case the display is well-suited for virtual reality applications. An example of a virtual reality head-mounted display is the Oculus Rift®.

In an alternative implementation, a head-mounted display may be at least partially transparent and/or sized and positioned to only occupy a portion of the user's field of view. A wearable heads-up display is a head- mounted display that enables the user to see displayed content but does not prevent the user from being able to see their external environment. Wearable heads-up displays are well-suited for augmented reality applications. Examples of wearable heads-up displays include: the Google Glass®, the Optinvent Ora®, the Epson Moverio®, the Microsoft HoloLens®, and the Sony

Glasstron®, just to name a few.

HUMAN-ELECTRONICS INTERFACES AND DEVICES A human-electronics interface mediates communication between a human and one or more electronic device(s). In general, a human-electronics interface is enabled by one or more electronic interface device(s) that: a) detect inputs effected by the human and convert those inputs into electric signals that can be processed or acted upon by the one or more electronic device(s), and/or b) provide sensory outputs (e.g., typically visual, auditory, and/or tactile) to the human from the one or more electronic device(s), where the user is able to sense the outputs and understand some information represented by the outputs. A human-electronics interface may be one directional or bidirectional, and a complete interface may make use of multiple interface devices. For example, the computer mouse is a one-way interface device that detects inputs effected by a user of a computer and converts those inputs into electric signals that can be processed by the computer, while the computer's display or monitor is a one-way interface device that provides outputs to the user in a visual form through which the user can understand information. Together, the computer mouse and display complete a bidirectional human-computer interface ("HCI"). A HCI is an example of a human-electronics interface.

A wearable electronic device may function as an interface device if, for example, the wearable electronic device: a) includes sensors that detect inputs effected by a user, and b) transmits signals to another electronic device based on those inputs. Sensor-types and input-types may each take on a variety of forms, including but not limited to: tactile sensors (e.g., buttons, switches, touchpads, or keys) providing manual control, acoustic sensors providing voice-control, electromyography sensors providing gestural control, and/or accelerometers providing gestural control. INTERACTING WITH HEAD-MOUNTED DISPLAYS

Portable electronic devices that include display screens typically require the user to use their hand(s) to carry the device and/or to orient the device so that the user may see, access, receive feedback from, and/or generally interact with the device's display screen. Occupying the user's hand(s) is an inconvenience that can significantly hinder the user's ability to interact with the portable electronic device and/or to interact with other aspects of their environment while operating the portable electronic device. However, this hindrance is at least partially overcome by making the display screen of the portable electronic device wearable, as is the case with head-mounted displays. Making the display screen of the portable electronic device wearable enables the user to see, access, and/or receive feedback from the display screen without using their hand(s). In recent years, head-mounted displays have begun to gain wider acceptance, with a number of recently introduced head- mounted display devices having the potential for widespread adoption by consumers.

To date, interfaces for controlling our otherwise interacting with content displayed on head-mounted displays have been unsatisfactory. In the case of wearable heads-up displays, the challenge is to simultaneously provide sophisticated control capabilities with an inconspicuous, substantially hands- free interface mechanism having a minimal form factor. Various schemes (e.g., voice control, a touch pad on-board the frames of the wearable heads-up display itself, a hand-held remote tethered to the wearable heads-up display through a wired connection, and so on) have been proposed but none of them satisfies all of the criteria specified above (namely, sophisticated control, inconspicuous and substantially hands-free, with minimal form factor).

Interacting with the content displayed on a wearable heads-up display remains a technical challenge that must be overcome in order for such displays to become more adopted by consumers. BRIEF SUMMARY

A system that enables interaction with content displayed on a head-mounted display may be summarized as including: a head-mounted display including: at least one display positioned in a field of view of at least one eye of a user when the head-mounted display is worn on a head of the user; a processor communicatively coupled to the at least one display; a non-transitory processor-readable storage medium communicatively coupled to the processor, wherein the non-transitory processor-readable storage medium stores processor-executable instructions and/or data that, when executed by the processor, cause the at least one display to display at least one object that is responsive to a selection operation performed by the user; and a wireless receiver to wirelessly receive signals, the wireless receiver communicatively coupled to the processor; an eye-tracker communicatively coupled to the processor, the eye-tracker to detect that the user is gazing at the at least one object displayed by the at least one display; and a wireless portable interface device with a form factor to be carried by or on the user, the portable interface device physically separate from the head-mounted display, wherein the portable interface device includes at least one actuator that, when activated by the user, causes the portable interface device to wirelessly transmit a signal. The selection operation performed by the user may comprise a substantially concurrent combination of gazing at the least one object displayed by the at least one display and activating the at least actuator of the portable interface device. In response to the selection operation performed by the user, a visual effect may be displayed on the at least one display of the head-mounted display. The non-transitory processor-readable storage medium may further store processor-executable instructions and/or data that, when executed by the processor in response to the wireless receiver wirelessly receiving the signal from the portable interface device, cause the processor to: request current gaze direction data from the eye-tracker; identify a particular object at which the user is gazing based on the current gaze direction data received from the eye- tracker, the particular object identified among the at least one object displayed by the at least one display; and cause the at least one display to display the visual effect on the particular object.

The portable interface device may be batteryless and may include a piezoelectric element communicatively coupled to the actuator and an antenna communicatively coupled to the piezoelectric element. The wireless receiver of the head-mounted display may include a radio frequency receiver. When activated by the user, the actuator may mechanically actuate the piezoelectric element. In response to the mechanical actuation, the

piezoelectric element may generate an electric signal. In response to the electric signal generated by the piezoelectric element, the antenna may transmit a radio frequency signal.

The portable interface device may be batteryless and may include a mechanical resonator physically coupled to the actuator. The wireless receiver of the head-mounted display may include at least one of: a microphone and/or a piezoelectric element tuned to be responsive to a sonic signal. When activated by the user, the actuator may mechanically actuate the mechanical resonator. In response to the mechanical actuation, the mechanical resonator may generate the sonic signal. The sonic signal may include an ultrasonic signal.

The object may include at least one object selected from a group consisting of: a menu item, a graphical button, a keyboard key, a notification, one of multiple objects displayed by the at least one display of the head- mounted display, a file, a folder, and an alphanumeric character. The portable interface device may include a wearable device selected from a group consisting of: a ring, a wristband, and an armband. The actuator of the portable interface device may include a button. The eye-tracker may be carried by and physically coupled to the head-mounted display.

A method of operating a system, wherein the system comprises a head-mounted display, an eye-tracker, and a wireless portable interface device, the portable interface device physically separate from the head-mounted display, may be summarized as including: displaying an object within a field of view of at least one eye of a user by at least one display of the head-mounted display; receiving a selection operation from the user by the system, wherein receiving a selection operation from the user by the system includes: detecting, by the eye tracker, that the user is gazing at the object; while detecting, by the eye tracker, that the user is gazing at the object, receiving, by the portable interface device, an activation from the user of an actuator of the portable interface device; in response to receiving, by the portable interface device, the activation from the user of the actuator of the portable interface device, wirelessly transmitting a signal by the portable interface device; and wirelessly receiving the signal by a wireless receiver of the head-mounted display; and in response to receiving the selection operation from the user by the system, displaying a visual effect by the at least one display of the head-mounted display. The head-mounted display may include a processor and a non- transitory processor-readable storage medium communicatively coupled to the processor. The non-transitory processor-readable storage medium may store processor-executable instructions and/or data and the method may include executing, by the processor, the processor-executable instructions and/or data stored in the non-transitory processor-readable storage medium to cause: the at least one display of the head-mounted display to display the object within the field of view of at least one eye of the user; and the at least one display of the head-mounted display to display the visual effect in response to the system receiving the selection operation from the user.

The portable interface device may be batteryless and may include a piezoelectric element communicatively coupled to the actuator and an antenna communicatively coupled to the piezoelectric element, and the wireless receiver of the head-mounted display may include a radio frequency receiver. In this configuration, receiving, by the portable interface device, an activation from the user of an actuator of the portable interface device may include receiving, by the portable interface device, a mechanical actuation of the piezoelectric element from the user. In response to the mechanical actuation, the piezoelectric element may generate an electric signal. Wirelessly transmitting a signal by the portable interface device may include wirelessly transmitting a radio frequency signal by the antenna of the portable interface device in response to the electric signal generated by the piezoelectric element. Wirelessly receiving the signal by a wireless receiver of the head-mounted display may include wirelessly receiving the radio frequency signal by the radio frequency receiver of the head-mounted display.

The portable interface device may be batteryless and may include a mechanical resonator physically coupled to the actuator. In this configuration, receiving, by the portable interface device, an activation from the user of an actuator of the portable interface device may include receiving, by the portable interface device, a mechanical actuation of the mechanical resonator from the user. In response to the mechanical actuation, the mechanical resonator may generate a sonic signal. Wirelessly transmitting a signal by the portable interface device may include wirelessly transmitting the sonic signal by mechanical resonator of the portable interface device. Wirelessly receiving the signal by a wireless receiver of the head-mounted display may include wirelessly receiving the sonic signal by the wireless receiver of the head- mounted display, wherein the wireless receiver of the head-mounted display includes at least one of: a microphone and/or a piezoelectric element tuned to be responsive to the sonic signal. The sonic signal generated by the

mechanical resonator of the portable interface device may include an ultrasonic signal.

The portable interface device may include an on-board power source and a radio frequency transmitter. Wirelessly transmitting a signal by the portable interface device may include wirelessly transmitting a radio signal by the radio frequency transmitter of the portable interface device, the radio signal having a frequency in a range of 10 MHz to 10 GHz. Wirelessly receiving the signal by a wireless receiver of the head-mounted display may include wirelessly receiving the radio signal by the wireless receiver of the head-mounted display, and wherein the wireless receiver of the head-mounted display includes a radio frequency receiver. A completely wearable human-electronics interface may be summarized as including: a wearable heads-up display including a wireless receiver; an eye-tracker carried by the wearable heads-up display; and a wearable actuator including a wireless transmitter to transmit wireless signals to the wireless receiver of the wearable heads-up display. The wearable heads- up display may further include a processor that is communicatively coupled to both the eye-tracker and the wireless receiver, the processor to effect interactions with content displayed by the wearable heads-up display in response to concurrent inputs from both the eye-tracker and the wearable actuator.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the drawings, identical reference numbers identify similar elements or acts. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes of various elements and angles are not necessarily drawn to scale, and some of these elements are arbitrarily enlarged and positioned to improve drawing legibility. Further, the particular shapes of the elements as drawn are not necessarily intended to convey any information regarding the actual shape of the particular elements, and have been solely selected for ease of recognition in the drawings.

Figure 1 is an illustrative diagram showing an exemplary system that enables interaction with content displayed on a head-mounted display in accordance with the present systems, devices, and methods.

Figure 2 is an illustrative diagram showing a human-electronics interface in which a user wears a system that enables the user to interact with displayed content in accordance with the present systems, devices, and methods.

Figure 3 is a flow-diagram showing an exemplary method of operating a system in accordance with the present systems, devices, and methods. DETAILED DESCRIPTION

In the following description, certain specific details are set forth in order to provide a thorough understanding of various disclosed embodiments. However, one skilled in the relevant art will recognize that embodiments may be practiced without one or more of these specific details, or with other methods, components, materials, etc. In other instances, well-known structures associated with head-mounted displays and electronic devices have not been shown or described in detail to avoid unnecessarily obscuring descriptions of the embodiments.

Unless the context requires otherwise, throughout the specification and claims which follow, the word "comprise" and variations thereof, such as, "comprises" and "comprising" are to be construed in an open, inclusive sense, that is as "including, but not limited to."

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. It should also be noted that the term "or" is generally employed in its broadest sense, that is as meaning "and/or" unless the content clearly dictates otherwise.

The headings and Abstract of the Disclosure provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.

The various embodiments described herein provide systems, devices, and methods for interacting with content displayed on head-mounted displays. Such includes an interface having a minimal form factor that enables sophisticated control interactions to be carried out in an inconspicuous, substantially hands-free manner. All of this is achieved with a multi-modal and fully-wearable interface that combines substantially concurrent inputs from both an eye tracker and a wireless portable interface device. Figure 1 is an illustrative diagram showing an exemplary system 100 that enables interaction with content displayed on a head-mounted display ("HMD") 1 10 in accordance with the present systems, devices, and methods. The HMD 1 10 of system 100 includes at least one display 1 1 1 (two such displays illustrated in Figure 1 ) positioned in the field of view of at least one eye of a user when HMD 1 10 is worn on the user's head. One or more display(s) 1 1 1 may employ one or more waveguide(s), one or more microdisplay(s), and/or any or all of the display technologies described in US Patent Application Publication 2015-0205134, US Non-Provisional Patent Application Serial No. 14/749,341 (now US Patent Application Publication 2015-0378164), US Non- Provisional Patent Application Serial No. 14/749,351 (now US Patent

Application Publication 2015-0378161 ), US Non-Provisional Patent Application Serial No. 14/749,359 (now US Patent Application Publication 2015-0378162), US Provisional Patent Application Serial No. 62/1 17,316, US Provisional Patent Application Serial No. 62/134,347 (now US Patent Application Publication 2016- 0274365), and/or US Provisional Patent Application Serial No. 62/156,736 (now US Non-Provisional Patent Application Serial Nos. 15/145,576, 15/145,609, and 15/145,583). HMD 1 10 also includes a processor 1 12 communicatively coupled to the at least one display 1 1 1 and a non-transitory processor-readable storage medium or memory 1 12 communicatively coupled to processor 1 12. Memory 1 13 stores data and/or instructions 1 14 (i.e., processor-executable instructions) that, when executed by processor 1 12 of HMD 1 10, cause the at least one display 1 1 1 to display at least one object 1 15 that is responsive to a selection operation performed by the user.

HMD 1 10 also includes a receiver 1 16 (e.g., a wireless receiver, or a wireless transceiver including a wireless receiver) operative to wirelessly receive signals. Receiver 1 16 is communicatively coupled to processor 1 12.

System 100 further includes an eye-tracker 1 17 that is operative to detect the eye position and/or gaze direction of at least one eye the user and communicatively coupled to processor 1 12. Eye-tracker 1 17 includes at least one camera or photodetector to measure light (e.g., visible light or infrared light) reflected from the at least one eye and processor 1 12 may determine the eye position or gaze direction of the at least one eye based on the measured reflections. Eye-tracker 1 17 may implement the technology described in US Provisional Patent Application Serial No. 62/167,767 (now US Non-Provisional Patent Application Serial Nos. 15/167,458 and 15/167,472). In the present systems, devices, and methods, eye-tracker 1 17 is operative to detect that the user is gazing at (e.g., looking, staring or generally pointing his or her eye(s) in the direction of) the at least one object 1 15 displayed by the at least one display 1 1 1. In the illustrated example of Figure 1 , eye-tracker 1 17 is carried by HMD 1 10, though in alternative implementations eye-tracker 1 17 may be physically separate from HMD 1 10.

System 100 provides a multi-modal interface for interacting with content displayed on a head-mounted display. A first mode of interaction (i.e., via eye position and/or gaze direction) is realized by eye-tracker 1 17. For a second mode of interaction, system 100 further includes a wireless portable interface device 120 with a form factor to be carried by or on the user. In the illustrated example of Figure 1 , portable interface device 120 has the general size and geometry of a ring to be worn on a finger or thumb of the user. In other implementations, portable interface device 120 may be a wristband or an armband, or may adopt a non-annular form factor that clips, sticks, or otherwise attaches to the user or the user's clothing (e.g., a pen with a clip). Portable interface device 120 is physically separate from HMD 1 10 and includes at least one actuator 121 (e.g., a button, switch, toggle, lever, dial, or similar

component) that, when activated by the user, causes portable interface device 120 to wirelessly transmit a signal from a wireless signal generator 122.

Portable interface device 120 may include a portable power source, such as a battery or a supercapacitor (i.e., capacitor with capacitance on the order of 0.01 F or greater). Alternatively, portable interface device 120 may be "batteryless." Throughout this specification and the appended claims, the term "batteryless" literally means "without any battery or batteries" (or any other equivalent device providing a similar function, such as a supercapacitor) and is generally used to indicate that the corresponding device (e.g., portable interface device 120) has no on-board battery or other source of pre-stored (i.e., generated off of the device and stored therein) power.

Portable interface device 120 is generally described as a wireless device. As used herein, the term "wireless" literally means "without any external wire-connections to anything" and is generally used to indicate that the corresponding device (e.g., portable interface device 120) is untethered with no external wire-connection(s) (or optical fiber connections, or cable connections, etc.) to any other electronic device or to any source of electric power. Thus, in implementations in which portable interface device 120 is both batteryless and wireless, then in the absence of any actuation (as described in more detail later on), portable interface device 120 is generally without any electric power.

Wearable electronic devices are typically larger and bulkier than other wearable accessories, such as traditional jewelry. This is at least in part because the form factor of wearable electronic devices typically must accommodate large and bulky components, such as an on-board battery, that are required for the wearable electronic device to operate. In the present systems, devices and methods, portable interface device 120 is wireless (and may, in some implementations, be batteryless) in order to remove the large and bulky electric components (e.g., a battery and/or a charging port, if batteryless) and provide a small and compact form factor not typically seen among wearable electronic devices. However, even in batteryless implementations, portable interface device 120 may still operate electrically using electric signals generated upon mechanical actuation by, for example, one or more on-board piezoelectric component(s).

Portable interface device 120 only includes one actuator or "button" 121 . Other implementations may include a second and even a third actuator, but in general portable interface device 120 includes very few actuators in order to minimize its form factor. In the illustrated example of Figure 1 , actuator 121 may provide a "select" function in combination with whatever the user is gazing at on at least one display 1 1 1 of HMD 1 10 as detected by eye-tracker 1 17 and determined by processor 1 12. As previously described, memory 1 13 of HMD 1 10 stores processor-executable instructions and/or data 1 14 that, when executed by processor 1 12 of HMD 1 10, cause the at least one display 1 1 1 to display at least one object 1 15 that is responsive to a selection operation performed by the user. In accordance with the present systems, devices, and methods, the selection operation performed by the user may comprise a substantially concurrent combination of gazing at the least one object 1 15 displayed by the at least one display 1 1 1 (as detected by eye-tracker 1 17) and activating the at least actuator 121 of the portable interface device 120. The selection operation may be effected by HMD 1 10 (e.g., by processor 1 12 of HMD 1 10) in response to receipt of a wireless "selection signal" 150 at receiver 1 16 transmitted from wireless signal generator 122 of portable interface device 120, and the selection operation may include "selecting" whatever object 1 15 on display 1 1 1 that eye tracker 1 17 identifies the user is looking/gazing at when the wireless selection signal 150 is receiver at receiver 1 16. To this end, when wireless receiver 1 16 of HMD 1 10 receives a wireless signal 150 from portable interface device 120, processor 1 12 executes processor-executable instructions and/or data 1 14 stored in memory 1 13, which cause processor 1 12 to: i) request current gaze direction data from eye-tracker 1 17; ii) identify a particular object 1 15 at which the user is gazing based on the current gaze direction data received from eye-tracker 1 17 (e.g., the particular object identified among at least one object displayed by at least one display 1 1 1 ); and iii) cause at least one display 1 1 1 to display the visual effect on the particular object 1 15.

Generally, in response to the selection operation performed by the user, a visual effect may be displayed or rendered on the at least one display 1 1 1 of HMD 1 10. The visual effect may include: highlighting the object 1 15, visually changing or modifying the object 1 15, displaying new or changed content elsewhere on the display 1 1 1 , or changing other aspects of the displayed content (including replacing the displayed content with new displayed content) based on the object 1 15 selected by the user. The object 1 15 may be any displayed image depending on the specific application and/or user interface, including without limitation: a menu item, a graphical button, a keyboard key, a notification, one of multiple objects displayed by the at least one display 1 1 1 of HMD 1 10, a file, a folder, and/or an alphanumeric character. In the illustrated example of Figure 1 , display 1 1 1 displays a representation of a virtual keyboard and the specific object 1 15 selected by the user corresponds to a specific key (i.e., letter) of the keyboard. Based on a typical qwerty keyboard configuration, the position of the selected key/letter corresponds to the letter Thus, as an exemplary application, system 100 may be used to enable the user to type by: i) displaying a virtual keyboard on at least one display 1 1 1 and, over a number of instances: ii) detecting which letter the user is gazing at by eye-tracker 1 17, and iii) selecting the letter that the user is gazing at when the user activates actuator 121 of portable interface device 120.

As described previously, the form factor of wearable electronic devices is a very important consideration in their design and can ultimately determine whether or not a wearable electronic device will be adopted by users. The present systems, devices, and methods provide a portable interface device 120 for interacting with content displayed on a HMD 1 10, where the portable interface device 120 has minimal bulk associated with its technological capabilities and may approximate the form factor of traditional jewelry or other accessories. This aspect of the portable interface device 120 is enabled by making the portable interface device 120 wireless and, in some

implementations, batteryless.

Even batteryless and wireless implementations of portable interface device 120 may still be used to wirelessly transmit signals to HMD 1 10. The present systems, devices, and methods provide two example configurations that enable portable interface device 120 to wirelessly transmit signals despite being a batteryless and wireless device.

As a first example, portable interface device 120 may include a piezoelectric element communicatively coupled to actuator 121 and a radio frequency antenna 122 communicatively coupled to the piezoelectric element. When activated (e.g., pressed, pushed, depressed, switched, or similar) by the user, actuator 121 mechanically actuates the piezoelectric element. In response to the mechanical actuation, the piezoelectric element generates an electric signal. This electric signal is communicatively coupled to radio frequency antenna 122 where, in response to the electric signal, antenna 122 wirelessly transmits a wireless (e.g. , radio frequency) signal. Antenna 122 (and associated circuitry) may be designed to wirelessly transmit a radio frequency or microwave frequency signal 150 having a specific frequency or within a specific range of frequencies. In this configuration, receiver 1 16 of HMD 1 10 includes a radio frequency or microwave receiver that is advantageously tuned to be responsive to radio or microwave signals in the range of signal 150 wirelessly transmitted by antenna 122 of portable interface device 120.

As a second example, portable interface device 120 may include a mechanical resonator 122 physically coupled to actuator 121. When activated (e.g., pressed, pushed, depressed, switched, or similar) by the user, actuator 121 mechanically actuates (e.g., strikes, impacts, oscillates, vibrates, or similar) mechanical resonator 122. In response to the mechanical actuation, mechanical resonator 122 generates a sonic, acoustic, or aural signal 150 of a specific frequency (or in a specific range of frequencies). The sonic signal may be an ultrasonic signal. In this configuration, receiver 1 16 of HMD 1 10 includes a microphone and/or a piezoelectric element that may be tuned to be

responsive to sonic signals in the range of sonic signal 150 wirelessly transmitted by mechanical resonator 122 of portable interface device 120.

Thus, in the present systems, devices, and methods, a signal 150 that is "wirelessly transmitted" may exist in a variety of different forms, including without limitation: a radio frequency signal, a sonic signal (such as an ultrasonic signal), an optical signal (generated by a mechanoluminescent material, such as a piezoluminescent alkali halide or a triboluminescent mineral), a photonic signal, a thermal signal, and so on. Generally, a signal that is "wirelessly transmitted" is any signal that is transmitted through any medium other than a conductive wire.

In implementations in which portable interface device 120 does include an on-board power source, such as a battery or a supercapacitor (i.e., in implementations in which portable interface device 120 is not batteryless), portable interface device 120 may be configured to transmit (and receiver 1 16 of HMD 1 10 may be configured to receive) more conventional wireless signals, such as short-wavelength radio wave signals in the range of 10MHz - 10GHz. For example, wireless signal generator 122 may include a wireless transmitter (e.g., a wireless transceiver including a wireless transmitter) designed and operated to transmit (and receiver 1 16 may be designed and operated to receive) wireless signals using an established wireless communication protocol, including without limitation: Bluetooth®, Bluetooth® Low-Energy, Bluetooth Smart®, ZigBee®, WiFi®, Near-Field Communication (NFC), or the like.

Figure 2 is an illustrative diagram showing a human-electronics interface 200 in which a user 201 wears a system that enables the user to interact with displayed content in accordance with the present systems, devices, and methods. The system comprises a HMD 210 and a portable interface device 220. HMD 210 is substantially similar to HMD 1 10 from Figure 1 and portable interface device 220 is substantially similar to portable interface device 120 from Figure 1 . In Figure 2, portable interface device 220 is shown having the form factor of a ring and worn on a finger of user 201 ; however, in alternative implementations portable interface device 220 may adopt a different form factor and be worn elsewhere on/by user 201 , such as a wristband, an armband, or a device that clips, affixes, or otherwise couples to user 201 or to an article of clothing worn by user 201 . In general, it is advantageous for the actuator (121 in Figure 1 , not visible in Figure 2) of portable interface device 220 to be easily and inconspicuously accessible to user 201 . In the case of a ring worn on the index finger of user 201 , an actuator on portable interface device 220 may be easily and inconspicuously activated by the adjacent thumb of user 201 . As previously described, activation of the actuator causes portable interface device 220 to wirelessly transmit a signal 250 (e.g., a radio frequency signal, a sonic signal such as an ultrasonic signal, an optical or photonic signal, or similar) and HMD 210 includes a receiver that wirelessly receives signal 250. If signal 250 is received by HMD 210 while an eye-tracker on HMD 210 detects that user 201 is gazing at an object displayed on HMD 210 that is responsive to a selection operation, then the combination of user 201 gazing at the object displayed by HMD 210 and substantially concurrently activating the actuator of portable interface device 220 effects the selection operation. In response to the selection operation, HMD 210 may display a visual effect to user 201 .

Figure 3 is a flow-diagram showing an exemplary method 300 of operating a system in accordance with the present systems, devices, and methods. The system (e.g., substantially similar to system 100 from Figure 1 ) comprises a HMD (e.g., 1 10), an eye-tracker (e.g., 1 17), and a portable interface device (e.g., 120), the portable interface device (120) physically separate from the HMD (1 10). As previously described, the portable interface device is a wireless device and, in some implementations, may be a batteryless device. Throughout the description of method 300 that follows, reference is often made to the elements of system 100 from Figure 1. A person of skill in the art will appreciate that the elements of system 100 are cited in relation to various acts as illustrative examples only and that the methods described herein may be implemented using systems and/or devices that differ from exemplary system 100 illustrated in Figure 1 . The scope of the present systems, devices, and methods should be construed based on the appended claims and not based on the illustrative example embodiments described in this specification. For this reason, throughout the description of method 300 references to elements of system 100 from Figure 1 are placed in parentheses to indicate that such references are non-limiting and used for illustrative purposes only.

Method 300 includes three acts 310, 320, and 330, though act 320 further includes four sub-acts 321 a, 321 b, 322, and 323. Those of skill in the art will appreciate that in alternative embodiments certain acts / sub-acts may be omitted and/or additional acts / sub-acts may be added. Those of skill in the art will also appreciate that the illustrated order of the acts / sub-acts is shown for exemplary purposes only and may change in alternative

embodiments.

At 310, at least one display (1 1 1 ) of the HMD (1 10) displays an object (1 15) within the field of view of at least one eye of the user. The object (1 15) is responsive to a selection operation performed by the user and may, as previously described, include without limitation: a menu item, a graphical button, a keyboard key, a notification, one of multiple objects displayed by the at least one display (1 1 1 ) of the HMD (1 10), a file, a folder, and/or an

alphanumeric character.

At 320, the system (100) receives a selection operation from the user. As previously described, the selection operation performed by the user may comprise a combination of two substantially concurrent portions: i) the user gazing at the at least one object (1 15) displayed by the at least one display (1 1 1 ) per 310 and ii) the user activating at least one actuator of the portable interface device (120). The selection operation involves multiple inputs of different modes and communication between different devices in system (100). Act 320 comprises sub-acts 321 a, 321 b, 322, and 323 that collectively define the receipt of the components of the selection operation by and between the components of the system (100).

At 321 a, the eye-tracker (1 17) of the system (100) detects that the user is gazing at the object (1 15) displayed at 310. Sub-act 321 a provides a first portion of act 320. More specifically, at sub-act 321 a the system (100) receives a first portion of the selection operation that is received at 320, that first portion corresponding to the "user gazing at the object (1 15)" portion of the selection operation detected and/or determined by the eye tracker (1 17).

At 321 b, the portable interface device (120) of the system (100) receives a second portion of the selection operation (i.e., an activation of at least one actuator (121 ) by the user). The portable interface device (120) may receive an activation of at least one actuator (121 ) from the user by, for example, having at least one actuator (121 ) be activated by the user. Sub-acts 321 a and 321 b are connected by a horizontal arrow in Figure 3 to indicate that the two sub-acts are substantially concurrent (i.e., sub-acts 321 a and 321 b are performed substantially concurrently). Generally, the user activates the actuator (121 ) of the portable interface device (120) per 321 b while the user is gazing at an object (1 15) that the user wishes to select, as detected by the eye- tracker (1 17) per 321 a. This combination of actions performed by the user (e.g. gazing while activating the actuator) is an example of a multi-modal selection operation in accordance with the present systems, devices, and methods.

At 322, a transmitter or signal generator (122) of the portable interface device (120) wirelessly transmits a signal (150) in response to the at least one actuator (121 ) being activated by the user at 321 b.

At 323, a receiver (1 16) of the HMD (1 10) wirelessly receives the signal (150) wirelessly transmitted by the portable interface device (120) at 322. Where sub-acts 321 a provided a first portion of act 320, the combination of sub- acts 321 b, 322, and 323 provides a second portion of act 320. More

specifically, over sub-acts 321 b, 322, and 323, the system (100) receives, via the portable interface device (120), a second portion of the selection operation that is received at 320, that second portion being the "user activating an actuator" portion of the selection operation provided by the portable interface device (120). With the selection operation thus received, method 300 proceeds to act 330.

At 330, the at least one display (1 1 1 ) of the HMD (1 10) displays or renders a visual effect in response to receiving the selection operation from the user per 320. As previously described, the visual effect may include, as non- limiting examples, any or all of: highlighting the object (1 15), visually changing or modifying the object (1 15), displaying new or changed content elsewhere on the display (1 1 1 ), or changing other aspects of the displayed content (including replacing the displayed content with new displayed content) based on the object (1 15) selected by the user. The HMD (1 10) of the system (100) may include a processor (1 12) communicatively coupled to the at least one display (1 1 1 ) and a non- transitory processor-readable storage medium or memory (1 13)

communicatively coupled to the processor (1 12). The memory (1 13) may store data and/or instructions (i.e., processor-executable instructions 1 14) that, when executed by the processor (1 12), cause: i) the at least one display (1 1 1 ) of the HMD (1 10) to display the object (1 15) within the field of view of at least one eye of the user per act 310, and ii) the at least one display (1 1 1 ) of the HMD (1 10) to display the visual effect to the user per act 330 in response to the system (100) receiving the selection operation from the user per act 320.

As described in the context of system 100 illustrated in Figure 1 , the portable interface device (120) of the system (100) may be implemented in a variety of different ways. Further details of sub-acts 321 b, 322, and 323 of method 300 may depend on the nature of the portable interface device (12) being implemented.

In a first example implementation, the portable interface device (120) may comprise a batteryless and wireless portable interface device that includes a piezoelectric element communicatively coupled to the actuator (121 ) and a radio frequency antenna (122) communicatively coupled to the

piezoelectric element and tuned to wirelessly transmit radio frequency signals (150) of a specific frequency or in a specific range of frequencies. The receiver (1 16) of the HMD (1 10) may comprise a radio frequency receiver (1 16) tuned to wirelessly receive radio frequency signals (150) of the specific frequency or in the specific range of frequencies. In this first example implementation, the portable interface device (120) may receive a mechanical actuation of the piezoelectric element from the user at sub-act 321 b of method 300. As before, the portable interface device (120) may receive or experience a mechanical actuation of the piezoelectric element from the user by, for example, having the piezoelectric element be mechanically actuated by the user. In response to the mechanical actuation, the piezoelectric element may generate an electric signal that communicatively couples to the radio frequency antenna (122) of the portable interface device (120), and in response to this electric signal the radio frequency antenna may wirelessly transmit a radio frequency signal (150) at sub-act 322 of method 300. At sub-act 323, the radio frequency receiver (1 16) of the HMD (1 10) may wirelessly receive the radio frequency signal (150).

In a second example implementation, the portable interface device (120) may comprise a batteryless and wireless portable interface device that includes a mechanical resonator (122) physically coupled to the actuator (121 ) and tuned to wirelessly transmit sonic, acoustic, or aural signals (150), such as ultrasonic signals, of a specific frequency or in a specific range of frequencies. The receiver (1 16) of the HMD (1 10) may comprise a microphone and/or a piezoelectric element tuned to be responsive to sonic signals (150) of the specific frequency or in the specific range of frequencies. In this second example implementation, the portable interface device (120) may receive a mechanical actuation of the mechanical resonator (122) from the user at sub- act 321 b of method 300. As before, the portable interface device (120) may receive or experience a mechanical actuation of the mechanical resonator (122) from the user by, for example, having the mechanical resonator (122) be mechanically actuated by the user. In response to the mechanical actuation, the mechanical resonator (122) may generate a sonic signal (150), such as an ultrasonic signal, which is wirelessly transmitted at sub-act 322 of method 300. At sub-act 323, the microphone and/or tuned piezoelectric element (1 16) of the HMD (1 10) may wirelessly receive the sonic signal (150).

In a third example implementation, the portable interface device (120) may comprise a wireless portable interface device that includes an on- board power source, such as a battery or a supercapacitor (and either a wireless charging coil or a tethered connector port for charging said on-board power source). In this third example implementation, the portable interface device (120) may include a wireless transmitter (122; e.g., an antenna and/or a wireless transceiver that includes a wireless transmitter) electrically coupled to the actuator (121 ) and operative to wirelessly transmit radio frequency signals (150) that embody an established wireless communication protocol, such as without limitation: Bluetooth®, Bluetooth® Low-Energy, Bluetooth Smart®, ZigBee®, WiFi®, Near-Field Communication (NFC), or the like. Such protocols typically employ radio frequency signals in the range of 1 GHz to 10GHz (with the exception of NFC, which operates in the 10MHz - 20MHz range) and may include pairing or otherwise establishing a wireless communicative link between the portable interface device (120) and the HMD (1 10). The receiver (1 16) of the HMD (1 10) may comprise a wireless receiver or antenna (e.g., a wireless transceiver that includes a wireless receiver or antenna) tuned to be responsive to radio frequency signals (150) of the specific frequency or in the specific range of frequencies transmitted by the wireless transmitter (122) of the portable interface device (120). In this third example implementation, the portable interface device (120) may receive an actuation of the actuator (121 ) from the user at sub-act 321 b of method 300. As before, the portable interface device (120) may receive or experience an actuation of the actuator (121 ) from the user by, for example, having the actuator (121 ) be physically actuated (e.g., depressed, switched, twisted, dialed, or similar, depending on the nature of the specific actuator) by the user. In response to the physical actuation, the wireless transmitter (122) may generate a radio frequency signal (150) which is wirelessly transmitted at sub-act 322 of method 300. At sub-act 323, the wireless receiver (1 16) of the HMD (1 10) may wirelessly receive the radio frequency signal (150).

The multi-modal interface described herein (comprising an eye tracker and a wireless actuator or button, both of which communicate with a wearable heads-up display) enables sophisticated control of and/or interactions with content displayed by the wearable heads-up display in an inconspicuous, substantially hands-free manner and has a minimal form factor. The

sophisticated and inconspicuous aspects of the control interactions are achieved, at least in part, by using the eyes (based on data provided by the eye tracker) to carry out the pointing and "identifying one among many" tasks that can be difficult to perform using hand-controlled interfaces. The eye (more particularly, the gaze thereof) is able to scan over and hone in on aspects of displayed content much more quickly and easily than a hand- or finger- controlled cursor; however, actually specifying a selection operation with the eye alone can be cumbersome because: a) the user is likely to inadvertently gaze at something he or she does not wish to actually select, and b) the mechanisms for doing so, such as a deliberate blink or an extended dwell time, are impractical and lead to an unpleasant user experience. The present systems, devices, and methods take advantage of the versatility and

scanning/honing capabilities of the eye/gaze but avoid the

specification/selection issues by employing a secondary input mode, a simple wearable actuator such as ring-based button, to actuate the

specification/selection function. This wearable actuator is too simplistic to enable sophisticated control interactions on its own, but when used in

conjunction with an eye tracker the resulting interface enjoys the best features of both modes. Like the eye tracker, the wearable actuator is similarly inconspicuous and it is "substantially hands-free" because it does not need to be carried by or held in the user's hand. In the case of a ring-based button worn on, for example, the user's index finger, the user may actuate the button simply using his or her thumb and this action may be performed while the user's hand or hands is/are also devoted to another task, such as carrying

something(s). The single-button actuator is also extremely low power (even batteryless in some implementations) and its simplicity enables very compact, minimal form factor designs.

The various embodiments described herein provide a multi-modal, portable, and completely wearable interface that enables a user to perform sophisticated interactions with content displayed on a wearable heads-up display in an inconspicuous, substantially hands-free manner. Furthermore, in implementations in which the eye tracker component is integrated into the wearable heads-up display (even integrated with the projection elements of the wearable heads-up display, as described in US Provisional Patent Application Serial No. 62/167,767, now US Non-Provisional Patent Application Serial Nos. 15/167,458 and 15/167,472) and the wireless actuator component is a wearable element, such as a ring-based button, the entire system provides a minimal and inconspicuous form factor. In some implementations, a user wearing the multi-modal interface described herein may be substantially indistinguishable from the same user wearing a conventional pair of eyeglasses and a conventional ring on his or her finger. Such is achieved, at least in part, by: the compact form factor of the wearable heads-up display; the compact form factor of the wearable (e.g., ring-based) actuator; integration of the eye tracker with the wearable heads-up display; and/or the wireless communication between the wearable actuator and the wearable heads-up display.

Throughout this specification and the appended claims, infinitive verb forms are often used. Examples include, without limitation: "to detect," "to provide," "to transmit," "to communicate," "to process," "to route," and the like. Unless the specific context requires otherwise, such infinitive verb forms are used in an open, inclusive sense, that is as "to, at least, detect," to, at least, provide," "to, at least, transmit," and so on.

The above description of illustrated embodiments, including what is described in the Abstract, is not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. Although specific embodiments of and examples are described herein for illustrative purposes, various equivalent modifications can be made without departing from the spirit and scope of the disclosure, as will be recognized by those skilled in the relevant art. The teachings provided herein of the various embodiments can be applied to other portable and/or wearable electronic devices, not necessarily the exemplary wearable electronic devices generally described above.

For instance, the foregoing detailed description has set forth various embodiments of the devices and/or processes via the use of block diagrams, schematics, and examples. Insofar as such block diagrams, schematics, and examples contain one or more functions and/or operations, it will be understood by those skilled in the art that each function and/or operation within such block diagrams, flowcharts, or examples can be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or virtually any combination thereof. In one embodiment, the present subject matter may be implemented via Application Specific Integrated Circuits

(ASICs). However, those skilled in the art will recognize that the embodiments disclosed herein, in whole or in part, can be equivalently implemented in standard integrated circuits, as one or more computer programs executed by one or more computers (e.g., as one or more programs running on one or more computer systems), as one or more programs executed by on one or more controllers (e.g., microcontrollers) as one or more programs executed by one or more processors (e.g., microprocessors, central processing units, graphical processing units), as firmware, or as virtually any combination thereof, and that designing the circuitry and/or writing the code for the software and or firmware would be well within the skill of one of ordinary skill in the art in light of the teachings of this disclosure.

When logic is implemented as software and stored in memory, logic or information can be stored on any processor-readable medium for use by or in connection with any processor-related system or method. In the context of this disclosure, a memory is a processor-readable medium that is an electronic, magnetic, optical, or other physical device or means that contains or stores a computer and/or processor program. Logic and/or the information can be embodied in any processor-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer- based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions associated with logic and/or information.

In the context of this specification, a "non-transitory processor- readable medium" can be any element that can store the program associated with logic and/or information for use by or in connection with the instruction execution system, apparatus, and/or device. The processor-readable medium can be, for example, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus or device. More specific examples (a non-exhaustive list) of the computer readable medium would include the following: a portable computer diskette (magnetic, compact flash card, secure digital, or the like), a random access memory (RAM), a readonly memory (ROM), an erasable programmable read-only memory (EPROM, EEPROM, or Flash memory), a portable compact disc read-only memory (CDROM), digital tape, and other non-transitory media.

The various embodiments described above can be combined to provide further embodiments. To the extent that they are not inconsistent with the specific teachings and definitions herein, all of the U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in the Application Data Sheet which are owned by Thalmic Labs Inc., including but not limited to: US Provisional Patent Application Serial No.

62/236,060, US Patent Application Publication 2015-0205134, US Non- Provisional Patent Application Serial No. 14/749,341 (now US Patent

Application Publication 2015-0378164), US Non-Provisional Patent Application Serial No. 14/749,351 (now US Patent Application Publication 2015-0378161 ), US Non-Provisional Patent Application Serial No. 14/749,359 (now US Patent Application Publication 2015-0378162), US Provisional Patent Application Serial No. 62/1 17,316, US Provisional Patent Application Serial No. 62/134,347 (now US Patent Application Publication 2016-0274365), and US Provisional Patent Application Serial No. 62/156,736 (now US Non-Provisional Patent Application Serial Nos. 15/145,576, 15/145,609, and 15/145,583) are

incorporated herein by reference, in their entirety. Aspects of the embodiments can be modified, if necessary, to employ systems, circuits and concepts of the various patents, applications and publications to provide yet further

embodiments.

These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific

embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.