Patent Description:
The disclosure relates generally to eyewear, and more specifically, to dimmable eyewear based on liquid-crystal technology.

Protective eyewear, such as sunglasses, can prevent high-energy light (e.g., sunlight) from damaging or discomforting the eyes. Sunglasses typically include lens that can block off and/or absorb at least some of the light to reduce the intensity of light entering the eyes, to protect the eyes from high-energy light. The lens may include, for example, a polarizer layer, a colored coating, etc., having a pre-configured light transmittance to block off and/or absorb a certain ratio of light power to prevent the eyes from receiving the full light power.

Although sunglasses can protect the eyes from high-energy light, sunglasses having a fixed light transmittance can create inconvenience to the user, especially as the user moves from an environment with relatively strong light intensity (e.g., outdoor) to an environment with relatively low light intensity (e.g., indoor or road tunnel). Because the sunglasses block off and/or absorb the same ratio of light power even in the low light environment, the visual perception of the user wearing the sunglasses can be significantly hampered in the low light environment. As a result, the user may need to take off the sunglasses in the low light environment, which degrades user experience.

Patent application <CIT> discloses eyewear comprising wisted nematic liquid crystal (LC) lenses activated depending on the intensity of the ambient light detected by solar cells. Patent application <CIT> discloses eyewear with a photosensor in a housing with a pinhole. The detected light is the input to vary the dimming of the LC lenses. Patent application <CIT> discloses eyewear with LC sectors activated as a function of the excited photosensors of a matrix within a housing. A lens directs the light towards said photosensors.

The invention relates to eyewear as defined in appended claim <NUM>.

In one aspect, the lens assembly further includes a first polarizer layer and a second polarizer layer. The lens and the liquid crystal layer are sandwiched between the first polarizer layer and the second polarizer layer. The liquid crystal layer comprises twist-nematic (TN) liquid crystal devices.

In one aspect, the lens is configured to selectively pass visible light of a frequency range associated with an orange color, such that light passed by the lens and by the first and second polarizer layers combine to have a white color.

In one aspect, the lens assembly further comprises a membrane between the lens and the first polarizer layer. The membrane is configured to reduce a birefringence effect exerted by the lens on the ambient light transmitted by the lens.

In one aspect, the '<NUM>'N liquid crystal devices have a twist angle range between <NUM> and <NUM> degrees. A first absorption axis of the first polarizer layer and a second absorption axis of the second polarizer layer forms <NUM> degrees.

In one aspect, the TN liquid crystal devices have a twist angle range between <NUM> and <NUM> degrees. A first absorption axis of the first polarizer layer and a second absorption axis of the second polarizer layer forms <NUM> degrees.

In one aspect, the liquid crystal layer includes at least one of: Guest-Host liquid crystal devices, electrically controlled birefringence (ECB) crystal devices, or Pi-cells.

In one aspect, the liquid crystal layer is sandwiched between a first substrate and a second substrate. The first substrate and the second substrate have different rubbing arrangements. An orientation of liquid crystal molecules of the liquid crystal layer vary between a homogeneous planar orientation and a homeotropic orientation in response to a signal applied by the driver circuit.

The eyewear further comprises a sensor coupled with the liquid crystal layer and with the driver circuit. The sensor is configured to generate sensor data based on the intensity of the ambient light. The driver circuit is configured to control the signal based on the sensor data.

The sensor comprises one or more solar cells.

In one aspect, the eyewear further comprises one or more transparent membranes comprising the one or more solar cells. The one or more transparent membranes are attached on at least one of the lens or the liquid crystal layer.

The eyewear further comprises a housing to enclose the one or more solar cells and the driver circuit. The housing further comprises a pin hole to expose the one or more solar cells to the ambient light.

In one aspect, the lens assembly is a first lens assembly comprising a first lens and a first liquid crystal layer. The eyewear comprises a second lens assembly comprising a second lens and a second liquid crystal layer. The eyewear comprises a connection structure to connect the first lens assembly and the second lens assembly. The housing is attached on the connection structure.

In one aspect, the housing is attached on the lens assembly.

The eyewear further comprises a light guide positioned between the pin hole and the one or more solar cells. The light guide is configured to: receive a narrow beam of ambient light received via the pin hole; convert the narrow beam into a sheet of ambient light; and direct the sheet of ambient light towards the one or more solar cells.

In one aspect, the light guide comprises an Acyclic material.

In one aspect, the eyewear further comprises a coating to partially cover the housing.

In one aspect, the eyewear further comprises a switch that enables a user to select the light transmittance of the lens assembly based on intensity of the ambient light. The driver circuit is configured to control the light transmittance of the lens assembly based on the selection from the switch.

In one aspect, the eyewear further comprises a camera positioned behind the lens assembly, the camera configured to receive light via the lens assembly to generate images. The eyewear further comprises a coating overlaid on a portion of the lens assembly and the camera, the coating configured to set an optical property of the portion of the lens assembly independently from the rest of the lens assembly.

In one aspect, the eyewear further comprises at least one of: a wireless interface to transmit and to receive radio signals; or an audio interface to input and output audio signals.

Illustrative embodiments are described with reference to the following figures:.

The figures depict embodiments of the present disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated may be employed without departing from the principles, or benefits touted, of this disclosure.

In the appended figures, similar components and/or features may have the same reference label.

In the following description, for the purposes of explanation, specific details are set forth in order to provide a thorough understanding of certain inventive embodiments. However, it will be apparent that various embodiments may be practiced without these specific details. The figures and description are not intended to be restrictive.

Protective eyewear, such as sunglasses, can prevent high-energy light (e.g., sunlight) from damaging or discomforting the eyes. Sunglasses typically include lens that can block off and/or absorb a certain ratio of light power to prevent the eyes from receiving the full light power. Although sunglasses can protect the eyes from high-energy light, the visual perception of the user wearing the sunglasses can be significantly hampered in the low light environment due to the absorption/blocking off of light power. As a result, the user may need to take off the sunglasses in the low light environment, which degrades user experience.

Embodiments of the present disclosure provide a dimmable eyewear which can address the problems described above. The eyewear comprises a lens assembly and a circuit. The lens assembly comprises a lens and a liquid crystal layer formed on the lens. The driver circuit is coupled with the liquid crystal layer and is configured to apply, based on an indication of an intensity of the ambient light, a signal to the liquid crystal layer to adjust the orientation of the liquid crystal molecules. The orientation adjustment of the liquid crystal molecules causes an adjustment to a light transmittance of the lens assembly based on the ambient light intensity.

The liquid crystal layer can adjust the transmittance of the lens assembly based on various mechanisms including, for example, twisted nematic (TN) effect, Guest-Host effect, electrically controlled birefringence (ECB), Pi-cells, etc. In all these examples, the driver circuit can adjust an electric field across the liquid crystal layer to adjust the orientations and alignments of the liquid crystal molecules in the liquid crystal layer, which can change the portion of incident light that passes through the lens assembly to the user's eyes, thereby adjusting the light transmittance of the lens assembly. The driver circuit can adjust the electric field based on the ambient light intensity. For example, the driver circuit can adjust the electric field to increase the light transmittance of the lens assembly in a low light environment (e.g., indoor), and to decrease the light transmittance of the lens assembly in a high light environment (e.g., outdoor).

The driver circuit can receive the ambient light intensity information from various sources. The dimmable eyewear includes optical sensors to sense the ambient light intensity. One example of the optical sensors can be solar cell, which can generate a voltage (or a current) that reflects the ambient light intensity, and provide the voltage/current to the driver circuit to generate a corresponding electric field for the liquid crystal layer. According to the invention, one or more solar cells are enclosed within a housing. The housing can be part of a connection structure that connects a pair of lens assemblies to form the eyewear, or can be behind the lens assembly of the eyewear for better appearance. The housing includes a pin hole to expose the solar cells to the ambient light. A light guide is provided between the pin hole and the solar cells to more uniformly distribute the ambient light over the solar cells surfaces, such that the solar cells output can better represent the ambient light intensity. In some examples, the eyewear may include switches which allow the user to select the light transmittance of the lens assembly, and the driver circuit can adjust the light transmittance of the lens assembly based on the user's selection.

Additional configurations are proposed to further improve user experience. For example, the lens assembly may include a pair of polarizers to sandwich the liquid crystal layer in between to create adjustable light transmittance based on the polarization angle of polarized light controlled by the liquid crystal layer. To reduce visual artifacts (e.g., a black-belt) caused by varying light absorption rate by the polarizers and perceived by the user via the eyewear, a slight mismatch can be introduced between the angle of rotation of the polarized light by the liquid crystal layer with respect to the angle between the polarization axes of the polarizers. As another example, the lens assembly may include an extra polyester film, such as Super Retarder Film (SRF®), to reduce or eliminate rainbow mura caused by birefringence of the lens followed by interferences at the polarizer layers and perceived by the user. As another example, the lens of the lens assembly can be configured to selectively pass visible light of a particular frequency range (e.g., an orange color) to compensate for the selective absorption of light by the two polarizers and for the retardation of visible light by the liquid crystal layer, which can improve visual perception of the user via the eyewear.

With embodiments of the present disclosure, the eyewear can adjust the light transmittance based on ambient light intensity, which allows the user to have a good visual perception via the eyewear irrespective of the environment the user is located in, while being protected from exposure to high-energy light. The user experience can be improved as a result.

<FIG>, <FIG>, <FIG>, and FIG. In illustrate an example of a dimmable eyewear <NUM> and its operations, according to some embodiments. As shown in <FIG>, eyewear <NUM> includes an optional frame <NUM> and one or more lens assemblies <NUM>. In the example of <FIG>, eyewear <NUM> may include two lens assemblies 104a and 104b connected by a connection structure <NUM>. In the example of <FIG>, eyewear <NUM> may include a single lens assembly <NUM> held by frame <NUM>. In some examples, eyewear <NUM> may be frameless, and may include a single lens assembly <NUM> or two lens assemblies 104a and 104b connected by connection structure <NUM>. In both examples, one or more lens assemblies <NUM> can have configurable light transmittance which can be configured/adjusted based on an ambient light intensity. Specifically, as shown in <FIG>, in an environment with high ambient light intensity (e.g., outdoor under the sun), the light transmittance of one or more lens assemblies <NUM> can be reduced to reduce the intensity of light that passes through one or more lens assemblies <NUM> into user's eyes (not shown in <FIG> - <FIG>), to protect the eyes from exposure to high energy light. Moreover, as shown in <FIG>, in an environment with low ambient light intensity (e.g., outdoor at night, indoor, etc.) the light transmittance of one or more lens assemblies <NUM> can be increased, so that the user can maintain a reasonable vision when wearing eyewear <NUM> in the low light environment.

<FIG> and <FIG> illustrate examples of one or more lens assemblies <NUM>, according to some embodiments. As shown in <FIG>, one or more lens assemblies <NUM> may include a lens <NUM>, a liquid crystal layer <NUM>, and optional first polarizer layer <NUM> and second polarizer layer <NUM>. Incident light <NUM> can enter one or more lens assemblies <NUM> and exit one or more lens assemblies <NUM> as output light <NUM> which can enter user's eye <NUM>. Lens <NUM> can be made of glass, polyester, polycarbonate, etc. In some examples, lens <NUM> can be flat to pass light without changing the light's property. In some examples, lens <NUM> can have a particular shape (e.g., being concave, convex, etc.) to vary the property of output light <NUM> to correct the user's vision (e.g., concave lens to correct myopia (near-sightedness), convex lens to correct hyperopia (far-sightedness), etc.). Near-sighted correction lens is usually spherically curved. Liquid crystal layer <NUM> can be made flexible but strong enough to survive three-dimensional deformation, to laminate liquid crystal <NUM> onto the near-sighted correction spherical lens.

Liquid crystal layer <NUM> can change the light transmittance of one or more lens assemblies <NUM> to adjust the portion of incident light <NUM> that passes through one or more lens assemblies <NUM> to become output light <NUM>. <FIG> illustrates one example configuration of liquid crystal layer <NUM> to provide adjustable light transmittance. As shown in <FIG>, liquid crystal layer <NUM> can be configured as a twisted nematic (TN) liquid crystal layer which can rotate the polarization axis of polarized light as the polarized light traverses the liquid crystal layer, with the angle of rotation adjustable by an electric field applied by a driver circuit across the liquid crystal layer. For example, as shown in <FIG>, if no electric field is applied, the liquid crystal molecules can have a twisted configuration to form a helical structure. The helical structure causes the polarization axis of the polarized light to rotate by a certain angle (e.g., a <NUM> degree angle) as the polarized light traverses through the liquid crystal layer. Moreover, if an electric field is applied, the liquid crystal molecules can align in parallel with the electric field. The polarization axis of the polarized light can be maintained and not rotated as the light traverses the aligned liquid crystal molecules.

Liquid crystal layer <NUM> can be sandwiched between first polarizer layer <NUM> and second polarizer layer <NUM>. First polarizer layer <NUM> can have a polarization axis A, whereas second polarizer layer <NUM> can have a polarization axis B. The two polarization axes can form a <NUM>-degree angle with respect to each other. Incident light <NUM> can enter via lens <NUM> and become linearly polarized by first polarizer layer <NUM>. The linearly polarized light can be rotated by liquid crystal layer <NUM> by an angle configured by the electric field as described above. The transmission rate of the linearly polarized light at zero field, labelled as TNW below, depends on wavelength according to the Gooch-Tarry theory, as follows:
<MAT>.

In Equation <NUM>, Ø can be the twist angle <MAT> in TN mode) and u can be a retardation index given by the following equation
<MAT>.

In Equation <NUM>, A can be the wavelength, Δn can be the birefringence of the liquid crystal mixture, whereas d is a constant.

Maximum light transmittance can be achieved in a case where no electric field is applied, such that liquid crystal layer <NUM> rotates the polarization axis of the polarized light such that it aligns with the polarization axis B of second polarizer layer <NUM>. Minimum light transmittance can be achieved when the polarization axis of the polarized right is not rotated due to application of an electric field, such that the polarization axis of the polarized light is not rotated and becomes perpendicular to the polarization axis B of second polarizer layer <NUM>. In such a case, the polarized light aligns with the absorption axis of second polarizer layer <NUM> and can be absorbed by second polarizer layer <NUM> at a maximum absorption rate. The electric field magnitude can be adjusted to adjust the angle of rotation of the polarized light, which can vary the portion of incident light <NUM> that passes through lens assemblies <NUM> as output light <NUM>.

TN liquid crystal can provide various technical advantages. For example, TN liquid crystal typically has extremely fast response characteristics and can adjust the light transmittance within a very short period of time (e.g., <NUM> milliseconds or less). Moreover, TN liquid crystal can also provide good light block property. For example, the minimum light transmittance of TN liquid crystal can reach <NUM>%. All these properties enable eyewear <NUM> to provide a wide configuration range of light transmittance as well as fast switching, which can improve user experience.

<FIG> illustrates another example configuration of liquid crystal layer <NUM> to provide adjustable light transmittance. As shown <FIG>, one or more lens assemblies <NUM> includes lens <NUM> and liquid crystal layer <NUM> but not first and second polarizer layers <NUM> and <NUM>. Liquid crystal layer <NUM> can include liquid crystal molecules <NUM>, which act as a host material, and dye molecules <NUM>, which act as a guest material. Liquid crystal molecules <NUM> and dye molecules <NUM> are sandwiched between two substrates <NUM> and <NUM>, which can be attached to or part of electrodes (not shown in <FIG>). Liquid crystal molecules <NUM> and dye molecules <NUM> can modulate the light transmittance of one or more lens assemblies <NUM> based on Guest-Host effect. Specifically, depending on the type of dye molecules <NUM>, dye molecules <NUM> can absorb light having an electric field that is perpendicular to (or parallel with) the long axis of the dye molecules. When the driver circuit applies an electric field across liquid crystal molecules <NUM> between substrates <NUM> and <NUM>, the orientation of liquid crystal molecules <NUM>, as well as dye molecules <NUM>, can be changed according to the electric field, which changes the relative orientation of the dye molecules with respect to the electric field of incident light <NUM>. As a result, the portion of incident light <NUM> absorbed by dye molecules <NUM>, and the light transmittance of one or more lens assemblies <NUM>, can be adjusted by the electric field applied across liquid crystal layer <NUM>.

Compared with TN liquid crystal, a liquid crystal layer that employs the Guest-Host effect needs not rely on a polarizer to absorb incident light, which can increase the overall achievable light transmittance of one or more lens assemblies <NUM>, while providing reasonable light blocking properties. For example, using the Guest-Host effect, the light transmittance range can be between <NUM>% to <NUM>%. To obtain a <NUM>% to <NUM>% transmittance range, two Guest-Host cells can be provided with their absorption axes separated by <NUM> degrees. No chiral dopant (or a very small amount of chiral dopant) is added to the Guest-Host mixtures.

Other techniques to achieve variable light transmittance are proposed. In one example, substrates <NUM> and <NUM> can be rubbed. The rubbing creates grooves on the surfaces of the substrates, which introduce surface energy to set the initial orientation of liquid crystal molecules <NUM> to a homogeneous planar orientation, at which the light transmittance of the liquid crystal layer is at the minimum. As a voltage is applied across substrates <NUM> and <NUM>, the electric field introduced between substrates <NUM> and <NUM> can counter the surface energy to tilt liquid crystal molecules <NUM> at an angle <NUM> with respect to each substrate, and the tilting angle, which increases with the voltage, can increase the light transmittance of the liquid crystal layer. For example, as shown in <FIG>, with a voltage v1, liquid crystal molecules <NUM> tilt at an angle θ1 with respect to each substrate, whereas with a voltage v2, liquid crystal molecules <NUM> tilt at an angle θ2 with respect to each substrate. As the orientation of liquid crystal molecules <NUM> transitions towards a homeotropic orientation, the light transmittance increases.

In some examples, to achieve a largely continuously/monotonic variable light transmittance (e.g., transmittance increases when the voltage decreases, and vice versa), a non-balanced or asymmetric rubbing arrangements can be provided. For example, substrates <NUM> and <NUM> can have different densities of grooves and can introduce different levels of surface energies to liquid crystal molecules <NUM>. Such arrangements can improve the stability of liquid crystal molecules <NUM> when the applied voltage is in the middle of the voltage range corresponding to the range of transmittance. Specifically, if the two substrates have similar rubbing and introduce similar surface energies, when the applied voltage is in the middle, the electric field may be countering two very similar surface energies at the same time. As a result, liquid crystal molecules <NUM> can become unstable and can exhibit different orientations, which can create domains and lead to haze, and an abrupt change of light transmittance may result. Having non-balanced or asymmetric rubbing arrangements between the substrates, an energy gradient can be formed between the two substrates, and the electric field from the applied voltage no longer counters two similar surface energies at the same time. This can improve the stability of liquid crystal molecules <NUM> and can ensure that liquid crystal molecules <NUM> are uniformly oriented in response to the voltage.

<FIG> illustrates a graph of light transmittance of liquid crystal layer <NUM> with respect to input voltage. AS shown in <FIG>, when a low voltage is applied across each cell, each cell can reorient the liquid crystal from a homeotropic to a homogeneous planar orientation, which can increase the light transmittance. When a high voltage is applied across each cell, each cell can be in the homeotropic planar orientation, which can reduce the light transmittance. Moreover, the light transmittance changes monotonically with respect to the voltage, including at the middle point (5V). With such arrangements, eyewear <NUM> can provide a wide configuration range of light transmittance, which can improve user experience.

Besides TN and Guest-Host effect, liquid crystal layer <NUM> can have other configurations to provide adjustable light transmittance. For example, liquid crystal layer <NUM> can be configured to provide electrically controlled birefringence (ECB). The ECB mode uses the applied voltage to change the tilt angle θ (also known as polar angle) of the liquid crystal molecules between the substrate normal and the molecule's long axis, which can change the birefringence of the liquid crystal. As another example, liquid crystal layer <NUM> can be configured as Pi-cells. The Pi-cell is also known as Optically Compensated Bend. In the Pi-cell, the pretilt angles on both substrates are in the same direction, also called parallel alignment of substrates. In Freedericksz ECB cells, the molecules may have a uniform alignment with a pretilt angle in the opposite direction on two substrates, also called anti-parallel alignment of substrates. An electric field can be applied across the Pi-cell and then the electric field can be switched off. The switching off of the electric field can cause the molecules to relax back to the original state, causing a flow of the molecules. The molecules in the mid-layer may be subject to a torque, which can cause a back-flow of the material and rotation of the molecules by a large angle to the original state. However this can slow down the switching speed. For Pi-cell, when the field is switched off, the molecules in the mid-layer is not subject to a torque when relaxing back to the off state. The molecules only rotates by a relatively small angle back to the original state, which can result in a faster switching speed.

In both examples of <FIG> and <FIG>, the driver circuit can apply an electric field applied across liquid crystal layer <NUM> to change the orientation and/or twist structure of the liquid crystal molecules. To reduce power consumption, liquid crystal layer <NUM> can be configured to have a relatively low switching threshold, such that a relatively weak electric field is needed to change the orientation and/or twist structure of the liquid crystal molecules. In some embodiments, the threshold voltage can be set at <NUM> - <NUM>. Various techniques can be used to reduce the threshold voltage of liquid crystal layer <NUM>, such as choosing liquid crystal that has a very high dielectric anisotropy, high elastic constant, and extremely high purity. The threshold electric field equation for twist nematic can be as follows:
<MAT>.

In Equation <NUM>, h can be cell thickness, K<NUM> can be the twist elastic constant, and Δε can be the dielectric anisotropy of liquid crystal mixture.

The driver circuit can output an AC voltage across liquid crystal layer <NUM> to generate the electric field. An AC voltage can be provided to drive the electric field to improve reliability and to avoid damage to the liquid crystal, since impurities in the liquid crystal can keep a DC current flowing which can decompose the liquid crystal molecules. The magnitude of the AC voltage can be configured based on the threshold voltage of liquid crystal layer <NUM>, as well as the ambient light intensity, such that the orientation and/or twisted angle of the liquid crystal molecules can reflect the ambient light intensity. With such arrangements, the light transmittance of one or more lens assemblies <NUM> can be configured based on the ambient light intensity.

The driver circuit can receive the ambient light intensity information from various sources. In some examples, the dimmable eyewear may include optical sensors to sense the ambient light intensity. <FIG> illustrates an example of eyewear <NUM> having an optical sensor <NUM> to sense the ambient light intensity. Optical sensor <NUM> can be positioned at, for example, connections structure <NUM>, and/or any location on frame <NUM>. Optical sensor <NUM> can include any device that can convert light into an electrical signal, such as photodiodes.

One example of optical sensor <NUM> can be photovoltaic cells, such as solar cells, which can provide a DC current or a DC voltage to the driver circuit that reflects the ambient light intensity. The solar cells can also provide electric power to the driver circuit such that no battery is needed, which can reduce the weight and size of eyewear <NUM>. The driver circuit can include a power converter to convert the DC current/voltage to the AC voltage to generate the electric field across liquid crystal layer <NUM>. In some examples, the solar cells can include miniature silicon-based solar cells having a rectangular shape and can have a range of dimensions between <NUM> millimeters (mm) x <NUM> to <NUM> x <NUM>.

<FIG> illustrate an example configuration of the solar cells in eyewear <NUM>. As shown in <FIG>, eyewear <NUM> can include a housing <NUM> to enclose solar cells <NUM>. Housing <NUM> can be positioned on frame <NUM> and behind lens assembly <NUM> (on a side facing the user, towards negative Y direction). Housing <NUM> also encloses the driver circuit which can be electrically connected to electrodes housed within frame <NUM>. The driver circuit can receive the DC current/voltage from solar cells <NUM> and generate a corresponding AC voltage, and transmit the AC voltage to the electrodes to generate a variable electric field across liquid crystal layer <NUM>.

According to the invention, as shown in <FIG>, frame <NUM> includes a pin hole <NUM> to expose the solar cells enclosed within housing <NUM> to ambient light. Pin hole <NUM> can be configured to facilitate light entering housing <NUM> from a front side of the user (e.g., from positive Y direction) and to block light from other directions (e.g., from a side direction, from above or below the user, etc.) from entering housing <NUM>. In some examples, pin hole <NUM> can have dimensions of <NUM> x <NUM>.

Pin hole <NUM> can increase the sensitivity of solar cells <NUM> to light directly emitted from a light source (e.g., the sun, lamps, etc.) which can accurately represent the ambient light intensity, while decreasing the sensitivity of solar cells <NUM> to reflect light which does not accurately represent the ambient light intensity. Such arrangements can improve the correlation between the output of solar cells <NUM> (and the driver circuit's output) and the ambient light intensity. Moreover, pin hole <NUM> can also prevent exposing the entirety of the solar cells while allowing the solar cells to collect light, which can improve the visual appearance of eyewear <NUM> while preserving the eyewear's capabilities of sensing ambient light intensity and making corresponding adjustment to the light transmittance.

According to the invention, eyewear <NUM> further includes a light guide <NUM> between pin hole <NUM> and the solar cells. Light guide <NUM> can receive a narrow beam of light via pin hole <NUM> and can project a sheet of light onto the solar cells, to more uniformly the light energy over the solar cells. Light guide <NUM> may include Acrylic material and can have a surface configured to diffuse light. A typical voltage range of the solar cell, based on the sheet of light received via light guide <NUM>, can be between <NUM> to <NUM>.

<FIG> and <FIG> illustrate other configurations of the solar cells and housing <NUM> not forming part of the invention. As shown in <FIG>, a coating <NUM> can be placed on frame <NUM>, on housing <NUM> (e.g., where housing <NUM> is part of connection structure <NUM> between two lens assemblies <NUM>), and/or on lens assembly <NUM> as shown in <FIG> to partially cover housing <NUM>. Coating <NUM> can be a darken coating and can be put on frame <NUM> and/or lens assembly <NUM> based on a sputtering process. Coating <NUM> can partially block the light and allow some light to enter housing <NUM> and solar cells <NUM>. Such arrangements can partially cover housing <NUM> and solar cells <NUM> to improve the visual appearance of eyewear <NUM><NUM> without pin hole <NUM>. Moreover, with the removal of pin hole <NUM>, solar cells <NUM> can receive a uniform sheet of light without light guide <NUM>. As a result, the size and weight of housing <NUM>, as well as the overall size and weight of eyewear <NUM>, can be reduced. The removal of pinhole <NUM> can also improve the flexibility of positioning of housing <NUM>. In <FIG>, housings 304a and 304b (as well as solar cells <NUM>) can be positioned behind, respectively, lens assemblies 104a and 104b and can be partially covered by coatings 320a and 320b to maximize the amount of light received by solar cells <NUM>.

<FIG> illustrates another configuration of the solar not forming part of the invention. As shown in <FIG>, the solar cells can be in the form of one or more transparent solar membranes <NUM> (e.g., membranes 330a, 330b, etc.). In some examples, one or more transparent solar membranes <NUM> can be formed (e.g., by electroplating) on the edges (e.g., upper and lower edges, side edges, etc.) of lens <NUM> (of lens assembly <NUM>) facing eye <NUM> of the user. The total surface of one or more transparent solar membranes <NUM> can also be configured based on the required range of voltages to be supplied by the driver circuit, which can be based on the range of transmittance to be provided by eyewear <NUM>. Compared with the silicon solar cell described with respect to <FIG>, transparent solar membranes <NUM> can be integrated with lens <NUM> as part of lens assembly <NUM> and does not take up extra space, which enables frame <NUM> to be more compact and to have a lighter weight.

Besides optical sensors (which may include photovoltaic cells), the driver circuit can also be manually controlled by the user to set the light transmittance of one or more lens assemblies <NUM>. <FIG> illustrates an example of eyewear <NUM> having an input interface <NUM> to receive user's input to control the light transmittance. Input interface <NUM> can include, for example, a mechanical switch, a touch pad, etc., and can be located at any location on frame <NUM>, temple <NUM> connected to frame <NUM>, etc. The microcontroller of the driver circuit can output different voltages based on the user's input detected at input interface <NUM> to adjust the electric field applied across the liquid crystal layer and the light transmittance of lens assemblies <NUM>. In some examples, a light transmittance range provided by manual control can be between <NUM>% to <NUM>%. The light transmittance range can be set based on the properties of the polarizers as explained above. Eyewear <NUM> also includes a battery, such as a lithium battery, to supply power to the driver circuit and to input interface <NUM>. With the liquid crystal threshold voltage set at <NUM>. 8V, the power consumption of eyewear <NUM> can be at <NUM> mW. Under such operational conditions, a typical lithium battery can provide a battery life of about <NUM> hours.

In addition to input interface <NUM>, eyewear <NUM> may include other interface circuits to improve user experience. For example, as shown in <FIG>, eyewear <NUM> may include a pair of cameras <NUM> (e.g., 406a, 406b, etc.) that are positioned behind lens assemblies 104a and 104b and can capture light via lens assemblies 104a and 104b to generate images. In some examples, eyewear <NUM> may include coatings 408a and 408b overlaid on, respectively, cameras 406a and 406b. The coatings may include, for example, an Indium Tin Oxide (ITO) layer etched on a substrate of liquid crystal layer <NUM> of each lens assembly. The ITO layer can form a region that operate separately from the rest of liquid crystal layer <NUM>. For example, the ITO layer can filter and control a wavelength range of the light that goes through liquid crystal layer <NUM> and captured by cameras 406a and 406b. As another example, the ITO layer can also form a separate pair of electrodes over the region of liquid crystal layer <NUM> overlaid by the ITO layer. Such arrangements allow the light transmittance of the region of liquid crystal layer <NUM> overlaid by the ITO layer to be controlled independently from the rest of liquid crystal layer <NUM> to, for example, improve the quality of the imaging operation by cameras 406a and 406b.

Moreover, referring to <FIG>, eyewear <NUM> may also include an interface circuit <NUM> in temple <NUM>. Interface circuit <NUM> may include, for example, a wireless interface circuit (e.g., based on the (e.g., Bluetooth® standard) and an audio input/output interface (e.g. a microphone, an audio speaker, etc.). The wireless interface circuit can receive, for example, radio signals carrying audio data, and provide the audio data to the audio speaker for outputting as audio signals. The wireless interface circuit can also transmit the image data captured by cameras 406a and 406b, and by the microphone, to other devices.

Besides adjustable light transmittance, additional techniques are proposed to further improve user experience provided by eyewear <NUM>, such as to mitigate visual artifacts caused by first and second polarizer layers <NUM> and <NUM>. As described above, lens assembly <NUM> may include first polarizer layer <NUM> and second polarizer layer <NUM> to sandwich liquid crystal layer <NUM> in between to create adjustable light transmittance. Light transmittance can be at a minimum when the liquid crystal molecules in liquid crystal layer <NUM> are aligned and the polarized light (polarized by first polarizer layer <NUM>) is not rotated and become perpendicular to the polarization axis of second polarizer layer <NUM>. In such a case, much of incident light <NUM> can be absorbed by second polarizer layer <NUM>, which can minimize the light transmittance of lens assembly <NUM>.

The light absorption rate of second polarizer layer <NUM>, however, can vary based on an incident angle of incident light <NUM> with respect to second polarizer layer <NUM>, which can create visual artifacts as the user sees through lens assembly <NUM> at different viewing angles and affect the visual perception of the user. <FIG> illustrates such an example. As shown in <FIG>, the user may look through different points of lens assembly <NUM> at different angles, with liquid crystal layer <NUM> configured to provide minimum light transmittance. When the user looks through a point at the center of lens assembly <NUM> (marked by label "C"), the absorption rate of second polarizer layer <NUM> can be highest, whereas when the user looks through a point near a side of lens assembly <NUM> (marked by label "D"), the absorption rate of second polarizer layer <NUM> can be reduced. Because of the difference in the absorption rate, the center of lens assembly <NUM> (where the light absorption rate is at the highest) may appear as a black belt compared with the side of lens assembly <NUM>. The appearance of the black belt can affect the visual perception of the user via eyewear <NUM> and can degrade user experience.

To reduce the appearance of the dark band, as shown in <FIG>, first polarizer layer <NUM> and second polarizer layer <NUM> can be oriented such that their polarization axes are not perpendicular to each other. With such arrangements, even when the liquid crystal molecules are aligned and do not rotate the polarized light from first polarizer layer <NUM>, the polarized light is not fully aligned with the absorption axis of second polarizer layer <NUM> and is not absorbed at the maximum absorption rate. Such arrangements can reduce the absorption rate difference of second polarizer layer <NUM> between the center and other parts of lens assembly <NUM>, which can reduce or eliminate the appearance of black belt at the center of lens assembly <NUM>. In some examples, first polarizer layer <NUM> and second polarizer layer <NUM> can be oriented such that their polarization axes form a <NUM> degree angle. In a case where maximum light transmittance is to be provided, liquid crystal layer <NUM> can be configured to rotate the polarized light by the <NUM> degree angle to match the <NUM> degree angle that separates the polarization axes of first polarizer layer <NUM> and second polarizer layer <NUM>.

In addition, other components of lens assembly <NUM> can be configured to compensate for visual artifacts created by first polarizer layer <NUM> and second polarizer layer <NUM>. For example, a combination of first polarizer layer <NUM> and second polarizer layer <NUM> may selectively absorb light of particular wavelength range in a case where their absorption axes are perpendicular to each other. As a result, the user may see blue light via first polarizer layer <NUM> and second polarizer layer <NUM>, whereas lens assembly <NUM> may also appear externally as blue, both of which can degrade user experience. To compensate for the visual artifacts created by the selectively absorption of light by first polarizer layer <NUM> and second polarizer layer <NUM>, as shown in <FIG>, lens <NUM> can be configured to selectively pass through orange light <NUM> (e.g., light of wavelength range <NUM>-<NUM> nanometers (nm)), while blocking light of other wavelengths. Meanwhile, first polarizer layer <NUM> and second polarizer layer <NUM> can pass blue light <NUM>, which can combine with orange light <NUM> to form white/transparent light when the light transmittance of lens assembly <NUM> is at the maximum. In a case where the light transmittance of lens assembly <NUM> is reduced, the user can also perceive dark color (e.g., grey, greyish black, etc.) via lens assembly <NUM> due to the combination of orange light <NUM> and blue light <NUM> and can have similar experience as wearing conventional sunglasses.

Moreover, as shown in <FIG>, a polyester film <NUM>, such as Super Retarder Film (SRF), can be added between lens <NUM> and first polarizer layer <NUM>. Polyester film <NUM> can be added to reduce or eliminate rainbow mura perceived by the user. The rainbow mura can be caused by uneven birefringence at lens <NUM>, which can convert linearly polarized light into circular polarized light. The circular polarized light can undergo interference at first polarizer layer <NUM> to form the rainbow mura. To reduce the rainbow mura, polyester film <NUM> can convert the circular polarized light from lens <NUM> into linearly polarized light, which can reduce the interference and the formation of rainbow mura as the light passes through first polarizer layer <NUM>.

Moreover, as shown in <FIG>, a lens <NUM> having diffraction gratings can be used in place of lens <NUM> and first polarizer layer <NUM>. Lens <NUM> can be made of quartz. The diffraction gratings can block light having a polarization axis parallel with the gratings and can provide a polarization effect similar to first polarizer layer <NUM>. The polarization axis of lens <NUM> can be perpendicular to second polarizer layer <NUM>, which enables adjustment of light transmittance of lens assembly <NUM> based on adjusting the rotation angle by liquid crystal layer <NUM>.

The foregoing description of the embodiments of the disclosure has been presented for the purpose of illustration; it is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Persons skilled in the relevant art can appreciate that many modifications and variations are possible within the scope of the claims.

Some portions of this description describe the embodiments of the disclosure in terms of algorithms and symbolic representations of operations on information. These algorithmic descriptions and representations are commonly used by those skilled in the data processing arts to convey the substance of their work effectively to others skilled in the art. These operations, while described functionally, computationally, or logically, are understood to be implemented by computer programs or equivalent electrical circuits, microcode, or the like. Furthermore, it has also proven convenient at times, to refer to these arrangements of operations as modules, without loss of generality. The described operations and their associated modules may be embodied in software, firmware, and/or hardware.

Steps, operations, or processes described may be performed or implemented with one or more hardware or software modules, alone or in combination with other devices. In some embodiments, a software module is implemented with a computer program product comprising a computer-readable medium containing computer program code, which can be executed by a computer processor for performing any or all of the steps, operations, or processes described.

Examples not forming part of the invention may also relate to an apparatus for performing the operations described. The apparatus may be specially constructed for the required purposes, and/or it may comprise a general-purpose computing device selectively activated or reconfigured by a computer program stored in the computer. Such a computer program may be stored in a non-transitory, tangible computer readable storage medium, or any type of media suitable for storing electronic instructions, which may be coupled to a computer system bus. Furthermore, any computing systems referred to in the specification may include a single processor or may be architectures employing multiple processor designs for increased computing capability.

Examples not forming part of the invention may also relate to a product that is produced by a computing process described herein. Such a product may comprise information resulting from a computing process, where the information is stored on a non-transitory, tangible computer readable storage medium and may include any embodiment of a computer program product or other data combination described herein.

Claim 1:
An eyewear (<NUM>) comprising:
a lens assembly (<NUM>) including:
a lens (<NUM>) and
a liquid crystal layer (<NUM>) formed on the lens;
and
a driver circuit coupled with the liquid crystal layer, the driver circuit configured to apply a signal to the liquid crystal layer based on an indication of an intensity of ambient light to control a light transmittance of the lens assembly;
a sensor (<NUM>) coupled with the liquid crystal layer and the drive circuit configured to generate a sensor output based on the intensity of the ambient light, the sensor comprising one or more solar cells, wherein the driver circuit is configured to control the signal based on the sensor output;
a housing (<NUM>) to enclose the one or more solar cells (<NUM>) and the driver circuit, the housing further comprising a pin hole (<NUM>) to expose the one or more solar cells to the ambient light; and
a light guide (<NUM>) positioned between the pin hole and the one or more solar cells, wherein the light guide is configured to:
receive a narrow beam of ambient light received via the pin hole;
convert the narrow beam into a sheet of ambient light; and
direct the sheet of ambient light towards the one or more solar cells.