Intelligent contact lens for detecting proportional light change

Abstract

There is provided a smart contact lens (400) for detecting a proportional change in intensity of incident light (126), comprising one or more preferably concentric rings (410-1, 410-2,..., 410-N) of the liquid crystal display (LCD) type, each ring operable between a state with lower light attenuation and a state with higher light attenuation; a circuit (420, 100, 101) for detecting a proportional change in the intensity of the incident light; and a controller (430) configured to operate the one or more rings based on an intensity of incident light and initiate repolarization of the one or more rings in response to the circuit (420, 100, 101 01) detecting that a change in proportion of the incident light intensity from a higher intensity state to a lower intensity state indicates that at least a user's blink action has started. A method of operating a smart contact lens and various uses of the circuit are also provided.

Description

[0001] This application is a divisional application of the invention patent application with the application date of May 19, 2020, application number 202080052627.5, and name “Smart contact lens for detecting proportional light changes”. Technical Field

[0002] The present disclosure relates generally to the field of smart contact lenses. In particular, the present disclosure relates to a smart contact lens that detects proportional changes in incident light intensity and a method of operating such a smart contact lens. Background Art

[0003] Smart contact lenses including circuits for detecting proportional light changes can be used in a variety of applications, including, for example, detecting eye blinks or detecting moving objects. To be able to detect light changes in, for example, dim indoor lighting conditions and bright outdoor lighting conditions, such circuits need to have a high dynamic range. Summary of the invention

[0004] To at least partially meet the above needs, the present disclosure seeks to provide an improved smart contact lens for detecting proportional changes in incident light intensity and a method of operating such a smart contact lens, as defined in the independent claims. Further embodiments are provided in the dependent claims.

[0005] According to one aspect of the present disclosure, a smart contact lens is provided. The smart contact lens includes one or more preferably concentric rings of a liquid crystal display (LCD) type, each ring being operable between a state having lower light attenuation and a state having higher light attenuation. The smart contact lens also includes circuitry for detecting a proportional change in incident light intensity; and a controller configured to operate the one or more rings based on the intensity of the incident light, and to initiate repolarization of the one or more rings in response to the circuitry detecting that the proportional change in the incident light intensity from a higher intensity state to a lower intensity state indicates that at least a blink action of the user has begun.

[0006] Smart contact lenses as described herein can provide a way to artificially mimic the function of the iris of an eye, for example. This may be helpful for individuals who have iris problems due to, for example, cancer, acute injury, or other reasons. By individually activating or deactivating one or more LCD-type rings arranged in the iris area, the light incident on the eye can be controlled based on, for example, the ambient light level.

[0007] Once the LCD ring is activated, it usually needs to be repolarized after a few seconds to avoid loss of contrast. This repolarization may be visible to the user of the contact lens in the form of an undesirable light flicker. However, if the LCD ring is instead repolarized when the eyelid is closed (e.g. during a blink), the repolarization can be performed without the user noticing a noticeable light flicker. For some LCD types, the ring may also need to be repolarized for other reasons. For example, if the ring is, for example, a guest-host display type, it may need to be repeatedly repolarized to prevent degradation of the crystal unit(s).

[0008] If the lens is mounted / provided in the eye, the intensity change may correspond to the onset of a blinking action, for example. By repolarizing the ring or rings during a blink (i.e. when the eyelids are closed), the user of the contact lens may experience little to no visual flicker due to the repolarization.

[0009] The circuit may include a light sensor configured to generate a photocurrent therethrough according to the intensity of incident light. The light sensor may be, for example, a photodiode, a photodetector, or a photoelectric sensor, or other element (i.e., a photosensitive device) that can provide a photocurrent therethrough according to the intensity of incident light.

[0010] The circuit may include an operational amplifier that may improve the signal-to-noise ratio of detected changes in incident light intensity.

[0011] The light sensor may be connected to the inverting input of the operational amplifier, which may improve the signal-to-noise ratio of the generated photocurrent.

[0012] The circuit may include a feedback loop. The feedback loop may connect the output of the operational amplifier to the inverting input of the operational amplifier. The feedback loop may include at least one circuit element. The at least one circuit element may have a logarithmic voltage-current correlation. The feedback loop implements negative feedback, which improves the stability of the circuit. The circuit element with a logarithmic voltage-current correlation allows the circuit to detect light changes in a high dynamic light range and, for example, operate in both dim indoor light and full sunlight conditions.

[0013] The circuit may include a high pass filter. The high pass filter may be configured to filter the signal output by the operational amplifier to generate a high pass filtered signal. The high pass filtered signal may have a higher signal-to-noise ratio.

[0014] The circuit may further include a comparison element. The comparison element may be configured to receive the high pass filtered signal. The comparison element may be configured to compare the high pass filtered signal with at least a first threshold. The comparison element may be configured to output a signal that changes in response to the amplitude of the high pass filtered signal passing through at least the first threshold to indicate a proportional change in the incident light intensity. The comparison element enables a clear detection of the associated proportional change in the incident light intensity, thereby reducing the requirements on the controller.

[0015] The operational amplifier may be a general purpose ultra low power operational amplifier and the circuit may be operated with low or minimal supply current consumption. This allows the circuit to be powered, for example, by a small thin film battery. Such a battery may be provided on the smart contact lens. Furthermore, due to the low number of components, the provided circuit requires less space, making it more suitable for use as a blink detector, for example, in a smart contact lens.

[0016] In some embodiments, the light sensor may be connected between an inverting input terminal and a non-inverting input terminal of the operational amplifier.

[0017] In some embodiments, the at least one circuit element may be or include a diode or at least an element having two terminals like a diode. In particular, diode-like behavior is understood to mean an element in which the voltage across the element has a logarithmic dependence on the current through the element.

[0018] In some embodiments, the at least one circuit element (e.g., a diode or a diode-like element) may be arranged in the feedback loop with one terminal toward the inverting input of the operational amplifier and the other terminal toward the output of the operational amplifier. Here, "toward" does not necessarily refer to the physical location of something (i.e., something physically pointing toward something), but rather to a topological arrangement. In other words, the at least one circuit element may be arranged such that, for example, an electrical path (or current) from the inverting input of the operational amplifier (or at least from a node to which the inverting input of the operational amplifier is connected) toward the output of the operational amplifier first reaches one terminal of the element and then reaches the other terminal of the element.

[0019] In some embodiments, the at least one circuit element may be a diode arranged in the feedback loop, with its cathode facing the inverting input of the operational amplifier and its anode facing the output of the operational amplifier. The light sensor may be, for example, a photodiode, and is arranged so that its cathode faces the inverting input of the operational amplifier and its anode faces, for example, the ground or the non-inverting input of the operational amplifier. In some embodiments, the at least one circuit element may be a diode arranged in the feedback loop, with its anode facing the inverting input of the operational amplifier and its cathode facing the output of the operational amplifier. The light sensor may be, for example, a photodiode, and is arranged so that its anode faces the inverting input of the operational amplifier and its cathode faces, for example, the ground or the non-inverting input of the operational amplifier.

[0020] In some embodiments, the comparison element may be a comparator. Such a comparator may, for example, output a signal that assumes one of two states (e.g., a higher voltage state and a lower voltage state) depending on whether the input signal to the comparator is above or below a threshold. The comparator may, for example, be implemented using a differential amplifier or the like, wherein the high-pass filtered signal is provided as one input and a signal indicating the first threshold is provided as another input, and wherein, depending on whether one input is greater than the other, the differential amplifier saturates, for example, at the positive rail or negative rail voltage, and vice versa. Of course, other ways of implementing a comparator may also be envisioned.

[0021] In some embodiments, the comparator may be a hysteresis comparator. In response to the high-pass filtered signal passing through both the first threshold and the second threshold different from the first threshold, the signal output by the comparator may then change. In other words, the comparator may not directly change its output signal when the high-pass filtered signal crosses a single (i.e., first) threshold, but only when the high-pass filtered signal also crosses the second threshold, the comparator will change its output signal, thereby introducing hysteresis behavior, because when the value of the high-pass filtered signal changes in one direction (e.g., from a lower value to a higher value), the output value of the comparator drawn according to the high-pass filtered signal will not follow the same curve as when the value of the high-pass filtered signal changes in the opposite direction (e.g., from a higher value to a lower value). It is envisioned that the hysteresis behavior of the comparator may be an inherent feature of the comparator, or may be implemented, for example, using a Schmitt trigger circuit or the like. The output signal provided using a hysteresis comparator can, for example, be less affected by noise that causes the high-pass filtered signal to fluctuate around the first threshold, and only changes its output state when the input (e.g., the high-pass filtered signal) exceeds the region of values ​​bounded by the first threshold and the second threshold.

[0022] In some embodiments, the high pass filter may have a corner frequency that may depend on the rate of change of the circuit required for a certain proportional change in the incident light intensity. In other words, the corner frequency of the high pass filter may be configured to allow a certain detection speed of the circuit.

[0023] In some embodiments, the high pass filter may be of the switched capacitor type.Such an implementation of the high pass filter may, for example, help limit the required on-chip area of ​​passive components such as resistors and / or capacitors.

[0024] According to a first variant of the present disclosure, a circuit for detecting a proportional change in the intensity of incident light is provided. Therefore, the circuit for detecting a proportional change in the intensity of incident light does not necessarily have to be arranged in a smart contact lens.

[0025] Therefore, according to a first variation, a circuit for detecting a proportional change in the intensity of incident light is provided. The circuit may include an operational amplifier. The circuit may include a light sensor configured to generate a photocurrent passing therethrough according to the intensity of the incident light. The light sensor may be, for example, a photodiode, a photodetector or a photoelectric sensor, or other elements (i.e., a photosensitive device) that can provide a photocurrent passing therethrough according to the intensity of the incident light. The light sensor may be connected to the inverting input of the operational amplifier. The circuit may include a feedback loop. The feedback loop may connect the output of the operational amplifier to the inverting input of the operational amplifier. The feedback loop may include at least one circuit element. The at least one circuit element may have a logarithmic voltage-current correlation. The circuit may include a high-pass filter. The high-pass filter may be configured to filter the signal output by the operational amplifier to generate a high-pass filtered signal. The circuit may further include a comparison element. The comparison element may be configured to receive the high-pass filtered signal. The comparison element may be configured to compare the high-pass filtered signal with at least a first threshold. The comparison element may be configured to output a signal that changes in response to the amplitude of the high pass filtered signal passing the at least first threshold value to indicate a proportional change in incident light intensity.

[0026] According to a second variation of the present disclosure, a method for detecting a proportional change in the intensity of incident light is provided. The method may include providing a light sensor. The light sensor may be configured to generate a photocurrent passing therethrough according to the intensity of the incident light. The method may include adjusting the voltage across the light sensor to zero or at least close to zero by using an operational amplifier and a feedback loop including at least one circuit element having a logarithmic voltage-current correlation. The method may include high-pass filtering the signal output from the operational amplifier to generate a high-pass filtered signal. The method may further include detecting a change in the intensity of the incident light by confirming that (the amplitude of) the high-pass filtered signal passes through at least a first threshold. This confirmation may be obtained, for example, using a comparison element (e.g., a comparator) as described herein with reference to the circuit of the first aspect.

[0027] In some embodiments, detecting a change in incident light intensity may comprise confirming that the high pass filtered signal passes both the first threshold and a second threshold different from the first threshold. This may be obtained using, for example, a hysteresis comparator as also described herein with reference to the circuit of the first aspect.

[0028] According to a third variant of the present disclosure, there is provided the use of a circuit (eg according to the first variant) and / or a method (eg according to the second variant) for detecting an eye blink as disclosed and described herein.

[0029] According to a fourth variant of the present disclosure, there is provided the use of a circuit and / or method for detecting motion of an illuminated object as disclosed and described herein.

[0030] According to a fifth variation of the present disclosure, a smart contact lens is provided. The lens may include one or more liquid crystal display (LCD) type rings. Each ring is operable between a state with lower light attenuation and a state with higher light attenuation. The one or more rings are preferably arranged concentrically or approximately concentrically. The rings preferably also have different inner diameters / outer diameters and are arranged in the order of inner diameter / outer diameter. The lens may include a circuit as disclosed and described herein, for example, a circuit according to the first aspect. The lens may further include a controller. The controller may be configured to operate the one or more rings based on the intensity of the incident light. The controller may be configured to receive a signal output by a comparator and, in response to a signal (received from the comparator) indicating a proportional change in the incident light intensity from a higher intensity state to a lower intensity state, initiate repolarization of the one or more rings.

[0031] According to a second aspect of the disclosure, there is provided a method of operating a smart contact lens comprising one or more preferably concentric rings of the liquid crystal display (LCD) type. The method may comprise detecting, for example using a circuit as comprised in the method of the first aspect and / or according to the first variant and / or according to, for example, the second variant, whether a proportional change in the intensity of incident light (impacting on a light sensor) corresponding to the start of at least a blinking action (for which the smart contact lens is provided) has occurred. The method may further comprise initiating a repolarization of the one or more rings as a response to detecting that at least such a blinking action has started.

[0032] The present disclosure relates to all possible combinations of features recited in the claims. Further, any embodiment described with reference to the circuit according to the first variant can be combined with any of the embodiments described with reference to the method according to the second variant, the various uses according to the third and fourth variants, the smart contact lens according to the fifth variant, and the method according to the second aspect, and vice versa.

[0033] Further objects and advantages of various embodiments of the present disclosure will be described below through exemplary embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Exemplary embodiments will be described below with reference to the accompanying drawings, in which:

[0035] Figure 1a and Figure 1b Schematically illustrating various embodiments of circuits according to the present disclosure;

[0036] Figure 2 Schematically illustrates graphs of various examples of signals provided in embodiments of circuits according to the present disclosure;

[0037] Figure 3 Schematically illustrates a flow chart of an embodiment of a method according to the present disclosure;

[0038] Figure 4 schematically illustrates an embodiment of a smart contact lens according to the present disclosure; and

[0039] Figure 5 Schematically shows a flow chart of an embodiment of the method according to the present disclosure;

[0040] In the accompanying drawings, unless otherwise specified, similar reference numerals will be used for similar elements. Unless explicitly stated to the contrary, the drawings show only those elements necessary to illustrate the example embodiments, and other elements may be omitted or merely presented for clarity. As shown in the figures, the dimensions of elements and regions may not necessarily be drawn to scale and may be exaggerated, for example, for illustrative purposes, and are therefore provided to show the overall structure of the embodiments. DETAILED DESCRIPTION

[0041] Exemplary embodiments will now be described more fully below with reference to the accompanying drawings. The accompanying drawings show currently preferred embodiments, however, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; on the contrary, these embodiments are provided to obtain thoroughness and completeness, and to fully convey the scope of the present disclosure to the skilled person.

[0042] refer to Figure 1a and Figure 1b , various embodiments of circuits for detecting proportional changes in incident light intensity will now be described in more detail.

[0043] Figure 1a The circuit 100 is schematically illustrated. The circuit 100 comprises a light sensor 120 having one terminal 122 connected to an inverting input 112 of an operational amplifier 110. Another terminal 124 of the light sensor 120 may be connected, for example, to ground, or directly to a non-inverting input 114 of the operational amplifier 110. When struck by incident light 126, the light sensor 120 generates a photocurrent I PD . Photocurrent I PD The size of depends on the intensity of the incident light 126.

[0044] The circuit 100 further includes a feedback loop 130. The feedback loop 130 connects the output 116 of the operational amplifier 110 back to the inverting input 112 of the operational amplifier 110. The feedback loop 130 includes a circuit element 132. The circuit element 132 has a logarithmic voltage-current dependence. In other words, the voltage across the circuit element 132 varies logarithmically with respect to the current through the circuit element 132. If no current or only very little current is allowed to enter the inverting input 112 of the operational amplifier 110 (for example, by assuming that the operational amplifier 110 is ideal or at least approximately ideal), the current through the circuit element 132 can be equal to the generated photocurrent I PD The voltage across the circuit element can be at least ln(I PD +α), where α is a term that can be zero or a finite number. Figure 1a Not shown, but conceivable, the feedback loop may include other elements in addition to circuit element 132 .

[0045] The circuit 100 further includes a high pass filter 140. The high pass filter 140 is connected to the output terminal 116 of the operational amplifier and is configured to filter the signal V output by the operational amplifier 110. AMP Filtering is performed to produce a high pass filtered signal V HPF .

[0046] The circuit 100 includes a comparison element 150 connected to receive the high pass filtered signal V from the high pass filter 140. HPF The comparison element 150 is configured to convert the high-pass filtered signal V HPF With at least a first threshold V T1 The comparison is performed and based on this the output signal V OUT The comparison element 150 is configured to make the comparison element 150 pass at least the first threshold value V T1 The high-pass filtered signal V HPF The amplitude of the response, signal V OUT changes to indicate a proportional change in the intensity of the incident light 126 .

[0047] Imagine signal V OUT , for example, in a first value (or state) V indicating a high intensity or a relatively high intensity of the incident light 126, for example S1 and a second value (or state) V indicating, for example, a low intensity or lower intensity of the incident light 126. S2 In some embodiments, the first value V S1 Higher than the second value V S2 , while in some other embodiments, the opposite is true. It is also contemplated that in some other embodiments, the signal V OUT does not change digitally, but in analog form, so that the signal V OUT has more than two different values. It is conceivable that, for example, V OUT A higher value indicates a higher intensity of the incident light 126, while V OUT A lower value of indicates a lower intensity of the incident light 126, and vice versa, and a change in the value indicates a proportional change in the intensity of the incident light 126. It is also assumed that the signal V OUT Alternatively, the signal V may include information of one or both of the intensity of the incident light 126 and the change in the intensity of the incident light 126 in the form of, for example, a data format. OUT For example, it may be a bit stream encoding such information of the incident light 126. In any case, the signal V OUT The information of the incident light 126 may be further provided to and used by, for example, a controller (not shown) to control one or more objects, for example, based on the information of the incident light 126. As will be described later herein, such an object may be, for example, a smart contact lens or the like. In other embodiments, the information of the change in the intensity of the incident light 126 may be used, for example, to detect the motion of the illuminated object.

[0048] Figure 1bThe circuit 101 is schematically illustrated. The circuit 101 comprises an operational amplifier 110 having an inverting input 112, a non-inverting input 114 and an output 116. In the circuit 101, a light sensor 120 is provided in the form of a photodiode. The photodiode 120 is connected between the inputs 112 and 114 of the operational amplifier 110 such that its cathode 122 is connected to the inverting input 112 and such that its anode 124 is connected to the non-inverting input 114 of the operational amplifier 110.

[0049] The feedback loop 130 connects the output 116 of the operational amplifier 110 back to the inverting input 112 of the operational amplifier 110. In the circuit 101, the feedback loop 130 includes a circuit element 132 in the form of a diode. The diode 130 is arranged so that its cathode 134 is connected to the inverting input 112 of the operational amplifier 110, and so that its anode 136 is connected to the output 116 of the operational amplifier 110. In other embodiments of the circuit 101, it is conceivable to reverse the direction of the two diodes 120 and 132, so that, for example, the cathode 122 of the diode 120 is directed toward the non-inverting input 114 and the anode 124 is directed toward the inverting input 112, and so that the cathode 134 of the diode 132 is directed toward the output 116 and the anode 136 is directed toward the inverting input 112.

[0050] The circuit 101 further includes a high pass filter 140. Figure 1b , the high pass filter 140 is shown to be formed by a voltage divider including a variable resistor 142 and a capacitor 144. Since the impedance of the capacitor 144 is inversely proportional to the frequency, the signal V AMP The various frequency components of will be distributed in different ways on capacitor 144 and variable resistor 142. Compared to being distributed on variable resistor 142, components with lower frequencies, for example, will be distributed more on capacitor 144, and vice versa for components with higher frequencies. This allows variable resistor 142 and capacitor 144 to be used together as an output signal V HPF The high-pass filter is used to filter the signal V AMP The corner (or cutoff) frequency of filter 140 may be adjusted according to the variable resistance provided by variable resistor 142. However, it is also contemplated that high pass filter 140 may be formed in other ways, such as as a switched capacitor high pass filter.

[0051] The circuit 101 includes a comparison element 150 in the form of a comparator. The comparator 150 is connected so that the voltage across the variable resistor 142 (eg, V HPF ) is provided between input terminals 152 and 154 of the comparator 150. The comparator 150 provides an output signal V according to the sign of the differential voltage on its input terminals 152 and 154.OUT Depending on the sign of the differential voltage, the output signal V OUT The comparator 150 can obtain one of two values ​​(for example, a positive voltage and a negative voltage, or a zero voltage and a positive voltage or a negative voltage). In the circuit 101, the positive input terminal 154 of the comparator 150 is grounded. Therefore, the comparator 150 can, for example, make the high-pass filtered signal V HPF When (amplitude) is positive, the output V OUT With one of these values, when the high-pass filtered signal V HPF When the amplitude is negative, the output V OUT This may correspond to a first threshold of the comparator 150 being equal to zero.

[0052] For example, to avoid when the signal V AMP When the output V fluctuates around the first threshold OUT When V HPF When it has passed both the first threshold and the second threshold different from the first threshold (in the same direction), its output V OUT For example, for the first threshold V T1 and the second threshold V T2 >V T1 , comparator 150 can be configured so that when V HPF Exceed V T2 When the output V OUT has a value when V HPF Lower than V T1 When the output V OUT In another embodiment, for the first threshold V T1 and the second threshold V T2 <V T1 , comparator 150 can be configured so that when V HPF Lower than V T2 When the output V OUT has a value when V HPF Exceed V T1 When the output V OUT has another different value. Other variations that provide the same functionality are also envisioned. More generally, the hysteresis comparator can provide an output signal V OUT In the signal V HPF has a state / value when it is within the region of values ​​defined by the first threshold and the second threshold, and when the signal V HPF Outside this area it has another state / value.

[0053] although Figure 1a and Figure 1bNot shown, but envisioned, is providing, for example, power supply rails to power, for example, the operational amplifier 110 and the comparison element / comparator 150 .

[0054] Now refer to Figure 1a and / or Figure 1b as well as Figure 2 The circuits according to the present disclosure are described in more detail (for example, referring to Figure 1a and Figure 1b The functions of circuits 100 and 101 are described.

[0055] For a light sensor in the form of a photodiode 120, for example, the photocurrent I generated through the photodiode 120 PD may depend on the intensity of the incident light 126. For example, it may be assumed that the photocurrent I PD The low value I at low intensity of incident light 126 PDL With a high value I at a high intensity of incident light 126 PDH >I PDL The photocurrent I PD The change ratio between the corresponding high and low values ​​of can be defined as CR = I PD H / I PDL >1. Figure 2 Schematic representation of the photocurrent I PD An exemplary graph 200 of the time variation of the photocurrent I t over a time interval between t=0 and t=te is shown. PD The intensity of the incident light 126 decreases from a higher value to a lower value, causing the photocurrent to decrease from a higher value I during the subinterval between t=0 and t=tf. PDH Change to a lower value I PDL , and then the intensity recovers to a higher value causing the photocurrent to return to a higher value I during the subsequent subinterval between t = tb and t = te PDH .

[0056] The photocurrent I generated PD The voltage V across the photodiode 120 can flow from the cathode to the anode of the photodiode 120. The operational amplifier 110 and the feedback loop 130 can convert the voltage V across the photodiode 120 PD is controlled / regulated to zero (or at least close to zero) and the photocurrent I PD If the anode 124 of the photodiode 120 and the non-inverting input terminal 114 of the operational amplifier 110 are connected to the potential V CM1 (e.g., ground), the potential at the inverting output terminal 112 of the operational amplifier 110 (and at the corresponding cathodes 122 and 134 of the photodiode 120 and the diode 130, respectively) will therefore be controlled / regulated to V CM1 .

[0057] Therefore, the voltage V across the diode 132 D will depend logarithmically on the photocurrent I PD Assuming that diode 132 is ideal, the voltage across diode 132 can be approximated as V D =V T *ln(I PD / I S +1), where V T is the thermal voltage, I S is the saturation current of the diode 132. Therefore, the signal V output by the operational amplifier 110 is AMP Assume V AMP =V D +V CM1 .

[0058] If the intensity of incident light 126 changes from a high value to a low value, the photocurrent will change from I PDH Change to IP D H / CR. This will make the signal V AMP Correspondingly from V T *ln(I PDH / I S +1)+V CM1 becomes VT*ln(I PDH / (CR*I S )+1)+V CM1 As long as I PDH / (CR*I S )>>1(i.e. exp(V D / V T )>>1), signal V AMP The change can be expressed as ΔV AMP =V T *ln(CR). This assumption can be made valid by, for example, adjusting the size of diode 132 accordingly. At room temperature, the thermal voltage can be assumed to be about 26 mV. For a decrease in light intensity by a factor of e (i.e., about 2.72), the voltage V output by operational amplifier 110 is AMP The difference is about 26 mV. This provides a high dynamic range for the circuit of the present disclosure and enables detection of proportional changes, such as from dim indoor lighting conditions to bright outdoor lighting conditions. Figure 2 Schematic showing the signal V AMP The graph 210 of the example over time includes the photocurrent I due to the time interval between t=0 and t=te described above. PD The change of the signal V during the same time interval AMP changes.

[0059] The high pass filter 140 removes the signal VAMP The DC component (i.e., constant component) of HPF . Figure 2 Schematic showing the signal V HPF The curve diagram 220 of the change over time. AMP Perform high-pass filtering, and the signal after high-pass filtering V HPF A negative transition 222 is included that marks the beginning of a change in the intensity of the incident light 126 .

[0060] Signal V HPF The negative transition 222 of is detected by the comparison element (e.g., comparator 150). In one embodiment, this is done by HPF The amplitude and the first threshold V T1 When the signal V HPF The amplitude is lower than the threshold V T1 , the comparison element 150 will output a signal V OUT From the first state (or voltage value) V S1 Change to the second state (or voltage value) V S2 Once the signal V HPF The amplitude is again higher than the threshold V T1 , output signal V OUT Then it returns to the first state V S1 This is Figure 2 , which schematically shows the signal V OUT An example graph 230 of the intensity of incident light 126 versus time is shown, where the intensity of incident light 126 is represented by signal V OUT The pulse 232 in the figure indicates.

[0061] In another embodiment, the comparison element (eg, a hysteresis comparator) also converts the signal V HPF With the second threshold V T2 is compared, and only when V HPF Passes (or has passed and in the same direction) the first threshold V T1 and the second threshold V T2 >V T1 When both, change the output signal V OUT Status. Figure 2 Another signal V schematically shown in OUT The example curve graph 240 of the change over time, once V HPF The amplitude is lower than the first threshold V T1 , signal V OUT From the first state V S1 Change to the second state V S2 , but until V HPF The amplitude exceeds the second threshold V T2 , it will return to the first state VS1 This configuration also provides a pulse 242 indicating that the intensity of the incident light 126 has begun to decrease, but in a manner that may be less sensitive to noise, for example. If, for example, the signal V HPF The amplitude is at the first threshold V T1 near fluctuations, an embodiment using a hysteresis comparator is used for each V HPF Crossing the first threshold V T1 Fluctuations will not (erroneously) output multiple pulses, and thus may provide a more stable way to indicate intensity changes in the incident light 126 than, for example, using a single threshold comparator as shown in graph 230 .

[0062] It should be noted that in Figure 2 In the figure, all graphs 200, 210, 220, 230 and 240 are plotted relative to the same time coordinate (t), but are plotted on separate vertical axes, which are also arranged vertically relative to each other for easier presentation. In each graph, the zero value of the corresponding vertical axis is represented by a small solid circle.

[0063] refer to Figure 3 , various embodiments of corresponding methods of detecting proportional changes in incident light intensity according to the present disclosure will now be described in more detail.

[0064] Figure 3 A flow chart of method 300 is schematically shown. In a first step S310, a light sensor is provided (if not already present). The light sensor may be configured to generate a photocurrent passing therethrough in dependence on the intensity of incident light (impacting the light sensor). In a next step S320, the voltage across the light sensor is regulated to zero using an operational amplifier and a feedback loop comprising at least one circuit element having a logarithmic voltage-current correlation. This causes the generated photocurrent passing through the light sensor to pass through at least one circuit element in the feedback loop. In a next step S330, the signal output from the operational amplifier is high pass filtered to generate a high pass filtered signal. In a next step S340, a change in the intensity of the incident light is detected by confirming that the high pass filtered signal passes at least a first threshold. As already described herein, this may, for example, correspond to the amplitude of the high pass filtered signal exceeding (or falling below) the at least one threshold. Although Figure 3 It is not shown, but the method 300 may operate in a looping manner and loop back to step S310 again to detect further changes in the incident light intensity.

[0065] In some embodiments of method 300, step S340 may alternatively include comparing the high pass with both a first threshold and a second threshold different from the first threshold, and detecting a change in the incident light intensity by confirming that the high pass filtered signal (in the same direction) passes through the first threshold and the second threshold (i.e., by confirming that the high pass filtered signal is outside the region of values ​​defined by the first threshold and the second threshold). For further details and / or advantages of this way of detecting a change in the incident light intensity, reference is made to the above description of using a hysteresis comparator as a comparison element.

[0066] refer to Figure 4 , one or more embodiments of smart contact lenses according to the present disclosure will now be described in more detail.

[0067] Figure 4 A smart contact lens 400 is schematically illustrated. The lens 400 includes one or more rings 410-1 to 410-N (where N is an integer and N≥1). The one or more rings 410-1 to 410-N are arranged concentrically, but it is also contemplated that other suitable arrangements of the one or more rings 410-1 to 410-N may be provided, such as approximately concentrically or in a similar manner. The rings 410-1 to 410-N may have different inner / outer diameters and may be arranged, for example, such that the smallest ring (e.g., ring 410-1) is in the center and the other rings (e.g., 410-2 to 410-N) are arranged outside the ring 410-1 in order of increasing diameter. Each ring 410-1 to 410-N may be operable between a state with lower light attenuation (e.g., an "open state") and a state with higher light attenuation (e.g., a closed / closed state).

[0068] In some embodiments, one or more rings 410-1 to 410-N may be, for example, of a twisted nematic (TN) or super twisted nematic (STN) type. In other embodiments, one or more rings 410-1 to 410-N may be of a guest-host liquid crystal type, including, for example, a mixture of a color dichroic dye, a chiral dopant, and a liquid crystal. This type may be beneficial because it may not require a polarizer to filter the light. This type may also be driven in a direct current (DC) mode rather than an alternating current (AC) mode. Driving one or more rings 410-1 to 410-N in a DC mode may further reduce energy consumption, thereby helping to further reduce, for example, the battery capacity required to drive the smart contact lens 400. It is also contemplated that one or more other types of rings other than LCDs may be used, as long as the same or similar functionality is achieved.

[0069] The lens 400 also includes a circuit 420. The circuit 420 may be, for example, a reference Figure 1a The circuit 100 described or, for example, with reference to Figure 1bThe circuit 420 is preferably arranged in the lens 400 so that if the lens 400 is inserted into the eye of a user (not shown), the rings 410-1 to 410-N obtain the function of an artificial iris of the eye, and so that, for example, when the eyelid is partially or completely closed, the light sensor of the circuit 420 is at least partially covered by the eyelid of the eye. It is also preferred that the lens 400 is further configured so that when inserted into the eye of the user, most of the lens 400 except the rings 410-1 to 410-N is arranged outside the field of view of the eye so as not to unnecessarily interfere with the user's vision.

[0070] Circuit 420 is configured to detect a proportional change in incident light intensity. The proportional change may be used by controller 430 to control one or more rings 410-1 to 410-N or to indicate the start of a blinking motion by a user.

[0071] The ratio change may be detected by measuring the absolute value of the incident light intensity and establishing a threshold and / or difference that corresponds to, for example, the onset of a user blinking action.

[0072] Ratio changes may also be detected by measuring the relative values ​​of incident light intensity and detecting associated changes (eg, exceeding a threshold value).

[0073] The proportional change may be measured using, for example, a photodiode, a photoresistor, and / or a photodetector.

[0074] The lens 400 includes a controller 430. The controller 430 is configured to operate one or more rings 410-1 to 410-N (i.e., operate each ring between its open and closed states as needed) based on the intensity of incident light (not shown) hitting the sensor of the circuit 420, thereby simulating the function of the iris together with the one or more rings 410-1 to 410-N. The controller 430 is also used to receive a signal V output by the circuit 420 (e.g., a comparison element or a light sensor). OUT , and as the signal V OUT Indicating a proportional change in the intensity of incident light from a higher state to a lower state (e.g., the onset of a blink action), repolarization of the one or more rings 410-1 to 410-N is initiated. Thus, the rings 410-1 to 410-N can be repolarized at the instant the user's eyes are closed, and so that little or no visual flicker occurs due to the repolarization. This provides an improvement over lenses that, for example, do not take into account whether the user has blinked when repolarizing one or more rings, which may result in flicker if, for example, the rings are repolarized when the eyelids are not closed or partially closed. As previously described herein, repolarizing one or more rings can prevent these rings from losing their contrast, or, if, for example, guest-host display type rings are used, degradation of the crystal unit(s) can also be avoided.

[0075] refer to Figure 5 The operation of the smart contact lens according to the present disclosure (e.g., reference Figure 4 Various embodiments of corresponding methods of contacting a lens 400 are described.

[0076] Figure 5 The flowchart of the method 500 is schematically shown. In the first step S510, using the circuit described above and / or the method described above (e.g., reference Figure 1a and Figure 1b Circuits 100 and 101 described and / or referenced Figure 3 The method 500 described above detects whether a proportional change in the intensity of the incident light occurs. This proportional change corresponds to at least the beginning of a blinking action (the contact lens is inserted in the eye). If it is detected that at least a blinking action has begun, the method 500 proceeds 501 to the next step S520. In step S520, as a response to detecting that the blinking action in step has begun, a repolarization of one or more rings is initiated. If at least the beginning of a blinking action is not detected in step S510, the method can stop or repeat 502 step S510 one or more times until the beginning of at least a blinking action is detected.

[0077] The present disclosure further contemplates the use of circuits and / or methods as described herein for, for example, detecting motion of an illuminated object. For example, a matrix of circuits configured to detect blinking may be provided on a surface that is illuminated in a variable manner as an object and / or, for example, a person moves. If one or more circuits detect a proportional change in the intensity of the incident light, such a change may be related to the motion of the object or, for example, a person. Compared to other techniques for detecting motion, for example based on image processing, the present disclosure may provide an improved way of detecting motion, including the benefits and advantages already enumerated herein when describing the use of a single circuit.

[0078] In general, the present disclosure provides a way to detect proportional changes in incident light intensity. Such detection can have a high dynamic range and work in conditions such as dim indoor lighting conditions as well as bright outdoor lighting conditions and in between. The circuits described herein can consume little power, occupy little physical space, and are suitable for use as, for example, blink detectors in smart contact lenses that can reliably detect blinking actions and are not affected by ambient light conditions. The circuits and methods also provide a way to detect motion of an illuminated object, for example.

[0079] Those skilled in the art realize that the present disclosure is by no means limited to the embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

[0080] Although features and elements are described above in particular combinations, each feature or element may be used alone without the other features and elements or in various combinations with or without the other features and elements.

[0081] Furthermore, variations of the disclosed embodiments are understood and effected by the skilled person in practicing the claimed invention by studying the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be used to advantage.

[0082] Various aspects of the present disclosure may be understood from the following enumerated example embodiments (EEE):

[0083] EEE 1. A circuit (100, 101) for detecting a proportional change in incident light intensity, comprising:

[0084] Operational amplifier (110);

[0085] A light sensor (120) configured to generate a photocurrent (I PD ), and connected to the inverting input terminal (112) of the operational amplifier;

[0086] A feedback loop (130) connecting the output (116) of the operational amplifier to an inverting input of the operational amplifier, the feedback loop comprising at least one circuit element (132) having a logarithmic voltage-current dependency;

[0087] A high pass filter (140) is configured to filter the signal (V AMP ) to generate a high-pass filtered signal (V HPF );as well as

[0088] A comparison element (150) is configured to compare the high-pass filtered signal with at least a first threshold and output a signal (V OUT ) which changes in response to the amplitude of the high pass filtered signal passing through the at least first threshold to indicate a proportional change in the incident light intensity.

[0089] EEE 2. The circuit as described in EEE 1, wherein the light sensor is connected between the inverting input terminal and the non-inverting input terminal (114) of the operational amplifier.

[0090] EEE 3. The circuit as described in EEE 1 or 2, wherein the at least one circuit element is or includes a diode or an element having at least two terminals like a diode.

[0091] EEE 4. The circuit as described in EEE 3, wherein the at least one circuit element is arranged in the feedback loop, with one terminal facing the inverting input terminal of the operational amplifier and the other terminal facing the output terminal of the operational amplifier.

[0092] EEE 5. The circuit as described in any one of the preceding EEEs, wherein the comparison element is a comparator.

[0093] EEE 6. The circuit of EEE 5, wherein the comparator is a hysteresis comparator, and wherein the signal output by the comparator changes in response to the high pass filtered signal passing both the first threshold and a second threshold different from the first threshold. EEE 6. The circuit of EEE 5, wherein the comparator is a hysteresis comparator, and wherein the signal output by the comparator changes in response to the high pass filtered signal passing both the first threshold and the second threshold different from the first threshold.

[0094] EEE 7. The circuit as described in any one of the preceding EEEs, wherein the corner frequency of the high pass filter depends on the required circuit change rate.

[0095] EEE 8. The circuit as described in any one of the preceding EEEs, wherein the high pass filter is of a switched capacitor type.

[0096] EEE 9. A method (300) for detecting a proportional change in incident light intensity, comprising:

[0097] providing a light sensor configured to generate a photocurrent therethrough according to the intensity of incident light (S310);

[0098] regulating the voltage across the light sensor to zero by using an operational amplifier and a feedback loop including at least one circuit element having a logarithmic voltage-current correlation (S320);

[0099] Performing high-pass filtering on the signal output by the operational amplifier to generate a high-pass filtered signal (S330); and

[0100] A change in the incident light intensity is detected by confirming that the high pass filtered signal passes at least a first threshold (S340).

[0101] EEE 10. The method of EEE 9, wherein detecting a change in the incident light intensity comprises confirming that the high-pass filtered signal passes both the first threshold and a second threshold different from the first threshold. EEE 11. The method of claim 10, wherein detecting a change in the incident light intensity comprises confirming that the high-pass filtered signal passes both the first threshold and a second threshold different from the first threshold.

[0102] EEE 11. Use of the circuit (100, 101) of any one of EEE 1 to 8 and / or the method (300) of EEE 9 or 10 for detecting eye blinks. EEE 12. Use of the circuit (100, 101) of any one of EEE 1 to 8 and / or the method (300) of EEE 9 or 10 for detecting eye blinks.

[0103] EEE 12. Use of a circuit (100, 101) as described in any one of EEE 1 to 8 and / or a method (300) as described in EEE 9 or 10 for detecting movement of an illuminated object. EEE 13.

[0104] EEE 13. A smart contact lens (400), comprising:

[0105] one or more preferably concentric rings (410-1, 410-2, ..., 410-N) of a liquid crystal display (LCD) type, each ring being operable between a state having a lower light attenuation and a state having a higher light attenuation;

[0106] A circuit (420, 100, 101) according to any one of EEE 1 to 8;

[0107] A controller (430) is configured to operate the one or more rings based on the intensity of the incident light, receive a signal (V OUT ) and in response to said signal indicating a proportional change in incident light intensity from a higher intensity state to a lower intensity state, initiating repolarization of the one or more rings.

[0108] EEE 14. A method (500) of operating a smart contact lens (400) comprising one or more preferably concentric rings (410-1, 410-2, ..., 410-N) of the liquid crystal display (LCD) type, the method comprising:

[0109] Using the circuit (100, 101) of any one of EEE 1 to 8 and / or the method (300) of any one of EEE 9 to 11, detecting whether a proportional change in incident light intensity corresponding to at least the start of a blink action has occurred (S510), and

[0110] In response to detecting that at least such a blinking action has begun, repolarization of the one or more rings is initiated (S520).

Claims

1. A smart contact lens (400), comprising: one or more liquid crystal display (LCD) type rings (410-1, 410-2, ..., 410-N), each ring operable between a state having lower light attenuation and a state having higher light attenuation; A circuit (420, 100, 101) for detecting a proportional change in incident light intensity; as well as A controller (430) is configured to operate the one or more rings based on the intensity of the incident light and initiate repolarization of the one or more rings in response to the circuit (420, 100, 101) detecting a proportional change in the incident light intensity from a higher intensity state to a lower intensity state indicating that at least a blinking action of the user has begun.

2. The smart contact lens of claim 1, wherein: The circuit (420, 100, 101) includes a light sensor (120) configured to generate a photocurrent (I PD ).

3. The smart contact lens according to claim 1 or 2, wherein: The circuit (420, 100, 101) includes an operational amplifier (110).

4. The smart contact lens of claim 3, wherein: The light sensor (120) is connected to the inverting input terminal (112) of the operational amplifier.

5. The smart contact lens of claim 3, wherein: The circuit (420, 100, 101) comprises a feedback loop (130) connecting an output terminal (116) of an operational amplifier to an inverting input terminal of the operational amplifier, the feedback loop comprising at least one circuit element (132) having a logarithmic voltage-current dependence.

6. The smart contact lens of claim 3, wherein: The circuit (420, 100, 101) includes a high pass filter (140) configured to provide a signal (V AMP ) to generate a high-pass filtered signal (V HPF ).

7. The smart contact lens of claim 6, wherein: The circuit (420, 100, 101) comprises a comparison element (150) configured to compare the high pass filtered signal with at least a first threshold value and output a signal (V OUT ) which changes in response to the amplitude of the high pass filtered signal passing through the at least first threshold to indicate a proportional change in the incident light intensity.

8. The smart contact lens of claim 7, wherein: The light sensor is connected between the inverting input terminal and the non-inverting input terminal (114) of the operational amplifier.

9. The smart contact lens of claim 7, wherein: The at least one circuit element is or comprises a diode or at least an element having two terminals like a diode.

10. The smart contact lens of claim 9, wherein: The at least one circuit element is arranged in the feedback loop, with one terminal facing the inverting input terminal of the operational amplifier and the other terminal facing the output terminal of the operational amplifier.

11. The smart contact lens of claim 7, wherein: The comparison element is a comparator.

12. The smart contact lens of claim 11, wherein: The comparator is a hysteresis comparator, and wherein the signal output by the comparator changes in response to the high pass filtered signal passing both the first threshold and a second threshold different from the first threshold.

13. The smart contact lens of claim 7, wherein: The corner frequency of the high pass filter depends on the desired rate of change of the circuit.

14. The smart contact lens of claim 7, wherein: The high pass filter is of switched capacitor type.

15. The smart contact lens of claim 1, wherein the rings are concentric.

16. A method (500) of operating a smart contact lens (400) comprising one or more preferably concentric rings (410-1, 410-2, ..., 410-N) of the liquid crystal display (LCD) type, the method comprising: Using the circuit (100, 101) according to any one of claims 1 to 15 included in the smart contact lens (400), detecting whether a proportional change in incident light intensity corresponding to at least the start of a blink action has occurred (S510); and In response to detecting that at least such a blinking action has begun, repolarization of the one or more rings is initiated (S520).

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