KR102564879B1 - Artificial retinal device with two-phase stimulation time control and method for operating the same - Google Patents

Abstract

An artificial retina device with a two-phase stimulation time control method and a driving method thereof are disclosed. The artificial retina device with a two-phase stimulation time control method according to an embodiment of the present invention has a pulse width proportional to the intensity of incident light and has a high (High) A two-phase signal generator for generating a first signal and a second signal, which are pulse signals that do not overlap each other, and current for optic nerve stimulation to the subject's retinal stimulation area based on the first signal and the second signal. It may include a stimulator that alternately applies.

Description

Two-phase stimulation time control type artificial retina device and method of driving the same

The present application relates to a two-phase stimulation time control type artificial retina device and a driving method thereof.

When photoreceptor cells that detect light in the retina lose their functions due to various factors such as age-related macular degeneration and retinitis pigmentosa, vision may be lost. Once vision is lost, complete recovery or treatment is currently impossible with medication or surgical therapy. In this regard, when the visual neural network, excluding photoreceptor cells, operates, electrical signals are applied to electrodes inserted into the retina to stimulate the nervous system, so that people who have completely lost their eyesight can achieve some degree of visual function (eg, It succeeded in making it perform big font classification, shape classification, etc.), which is called artificial retina technology.

On the other hand, the artificial retina described above basically transfers stimulation charges proportional to the intensity of incident light to the cells, helping the subject to recognize the difference in brightness of light. Conventional technologies for this are largely a stimulation intensity control method and stimulation There are two ways to control the number of times.

First, the artificial retina of the stimulation intensity control method controls the amplitude of the stimulation signal through a system that generates a bias voltage or current of the stimulation stage that is proportional to the intensity of incident light. Therefore, the artificial retina of the stimulation intensity control method has a problem in that a high supply voltage is required to generate stimulation in a wide dynamic range.

Next, the artificial retina of the stimulation number control method adjusts the number of stimulation signals in proportion to the intensity of incident light, thereby adjusting the amount of charge to be delivered to the cells. However, since the stimulation period at which the human eye responds to artificial stimulation is approximately 4 to 6 Hz, there is a problem in that a high operating frequency is required to generate a plurality of stimulation signals during one stimulation period.

The background technology of the present application is disclosed in Korean Patent Registration No. 10-1856014.

The present invention is to solve the problems of the prior art described above, and provides a two-phase stimulation time control type artificial retina device capable of implementing efficient stimulation with low power compared to the stimulation intensity control method and the stimulation frequency control method, which are conventional artificial retina technologies. intended to do

However, the technical problem to be achieved by the embodiments of the present application is not limited to the technical problems described above, and other technical problems may exist.

As a technical means for achieving the above technical problem, the artificial retina device of the two-phase stimulation time control method according to an embodiment of the present application has a pulse width proportional to the intensity of incident light, and a high state is mutually A two-phase signal generator that generates first and second signals, which are non-overlapping pulse signals, and a stimulator that alternately applies a current for optic nerve stimulation to the subject's retinal stimulation area based on the first and second signals can include

In addition, the two-phase signal generator generates a clock signal or a rising edge of a reference signal corresponding to the clock signal based on a photodiode that generates a photocurrent proportional to the intensity of the light and a delay time that is inversely proportional to the intensity of the photocurrent. It may include a plurality of delay circuits for delaying.

In addition, the clock signal has a duty cycle of 50%, the rising edge of the reference signal is generated corresponding to the falling edge of the clock signal, and the reference signal maintains a high state during the period of the clock signal. It may be a signal that

In addition, the plurality of delay circuits include a first delay circuit for delaying the rising edge of the clock signal once according to the delay time, and sequentially delaying the rising edge of the reference signal twice according to the delay time. A second delay circuit and a third delay circuit may be included.

Also, the first signal may be an output signal of the first delay circuit.

Also, an input signal of the first delay circuit may be an output signal of an AND gate having the clock signal and the reference signal as inputs.

Also, the second signal may be an output signal of an AND gate having an opposite signal of the first signal and an output signal of the third delay circuit as inputs.

Also, when the period of the clock signal is T _clk and the delay time is t _rd , the pulse widths of the first signal and the second signal may be T _clk /2−t _rd .

In addition, the stimulator may include a first electrode and a second electrode disposed to face each other with respect to the retina stimulation site.

In addition, the stimulator applies a current in a direction from the first electrode to the second electrode based on the first signal, and applies a current in a direction from the second electrode to the first electrode based on the second signal. current can be applied.

In addition, the stimulation device may include a switch selectively driven according to the first signal and the second signal.

On the other hand, the driving method of the artificial retina device of the two-phase stimulation time control method according to an embodiment of the present application is a pulse signal having a pulse width proportional to the intensity of incident light and a high state that does not overlap with each other. It may include generating a first signal and a second signal, and alternately applying a current for optic nerve stimulation to a retinal stimulation site of a subject based on the first signal and the second signal.

In addition, the generating may include delaying generation of a clock signal or a rising edge of a reference signal corresponding to the clock signal based on the generating of a photocurrent proportional to the intensity of light and a delay time inversely proportional to the intensity of the photocurrent. steps may be included.

The delaying may include delaying the rising edge of the clock signal once according to the delay time and sequentially delaying the rising edge of the reference signal twice according to the delay time. .

The above-described problem solving means are merely exemplary and should not be construed as intended to limit the present disclosure. In addition to the exemplary embodiments described above, additional embodiments may exist in the drawings and detailed description of the invention.

According to the above-described problem solving means of the present application, it is possible to provide an artificial retina device of a two-phase stimulation time control method capable of implementing efficient stimulation with low power compared to the stimulation intensity control method and the stimulation frequency control method, which are conventional artificial retina technologies.

According to the above-described problem solving means of the present application, stimulation charges proportional to light intensity are generated even at a low operating voltage, and a high operating frequency is not required, so an artificial retina system operating with lower power can be implemented.

However, the effects obtainable herein are not limited to the effects described above, and other effects may exist.

1 is a schematic configuration diagram of a two-phase signal generator of an artificial retina device of a two-phase stimulation time control method according to an embodiment of the present invention.
2 is a timing diagram of a 2-phase signal including a first signal and a second signal generated by a 2-phase signal generator and a clock signal and reference signal for generating the 2-phase signal.
3 is a schematic configuration diagram of a delay circuit of a two-phase signal generator.
4 is a schematic configuration diagram of a stimulator of a two-phase stimulation time control type artificial retina device according to an embodiment of the present invention.
5 is a view showing a comparison between a stimulation signal generated by a two-phase stimulation time control artificial retina device according to an embodiment of the present invention and a stimulation signal of a conventional artificial retina device.
6 is an exemplary view showing an artificial retina device implemented in a chip form of a two-phase stimulation time control method according to an embodiment of the present application.
7 is a diagram showing measurement results of two-phase signals generated by an artificial retina device of a two-phase stimulation time control method according to an embodiment of the present application.
8 is a diagram visualizing the result of adjusting the stimulation time according to the pattern of light applied to the artificial retina device of the two-phase stimulation time control method according to an embodiment of the present application.
9 is a graph showing a correlation between the intensity of light and the pulse width of a two-phase signal according to a plurality of frequencies of a clock signal.
10 is an operation flowchart of a method of driving an artificial retina device of a two-phase stimulation time control method according to an embodiment of the present invention.

Hereinafter, embodiments of the present application will be described in detail so that those skilled in the art can easily practice with reference to the accompanying drawings. However, the present disclosure may be implemented in many different forms and is not limited to the embodiments described herein. And in order to clearly describe the present application in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the present specification, when a part is said to be “connected” to another part, it is not only “directly connected”, but also “electrically connected” or “indirectly connected” with another element in between. "Including cases where

Throughout the present specification, when a member is referred to as being “on,” “above,” “on top of,” “below,” “below,” or “below” another member, this means that a member is located in relation to another member. This includes not only the case of contact but also the case of another member between the two members.

Throughout the present specification, when a certain component is said to "include", it means that it may further include other components without excluding other components unless otherwise stated.

The present application relates to a two-phase stimulation time control type artificial retina device and a driving method thereof. The artificial retina device 10 (hereinafter referred to as 'artificial retina device 10') of a two-phase stimulation time control method according to an embodiment of the present application includes a two-phase signal generator 100 and a stimulator 200. can include

Hereinafter, the structure and function of the two-phase signal generator 100 of the artificial retina device 10 will be described with reference to FIGS. 1 to 3 .

The two-phase signal generator 100 has a pulse width proportional to the intensity of incident light and generates a first signal AP and a second signal CP, which are pulse signals in which high states do not overlap each other. can be

In other words, the two-phase signal generator of the artificial retina device 10 disclosed herein is applied to the artificial retina device 10 so that the stimulus duration applied to the retinal stimulation site is determined according to the intensity of light. A two-phase signal having a pulse width determined in response to the intensity of light may be generated, and the generated two-phase signal may be transmitted to the stimulator 200 that applies the stimulus to the subject's retinal stimulation site.

1 is a schematic configuration diagram of a two-phase signal generator of an artificial retina device of a two-phase stimulation time control method according to an embodiment of the present invention.

Referring to FIG. 1 , a two-phase signal generator 100 may include a photodiode 110 and a plurality of delay circuits 120 .

For example, the plurality of delay circuits 120 of the two-phase signal generator 100 include the first delay circuit 121 involved in generating the first signal AP and the second delay circuit 120 as will be described in detail below. It may include a second delay circuit 122 and a third delay circuit 123 involved in generating the signal CP, but is not limited thereto, and the delay of the plurality of delay circuits 120 The number of mounted circuits may be determined as necessary with various values according to embodiments of the present invention.

The photodiode 110 may generate a photocurrent (I _PD ) proportional to the intensity of light applied to the artificial retina device 10 . In other words, the photodiode 110 may sense light incident on the artificial retina device 10 (Light Sensing).

The plurality of delay circuits 120 delay generation of the clock signal CLK or the rising edge of the reference signal SE corresponding to the clock signal CLK based on a delay time inversely proportional to the intensity of the photocurrent I _PD . can make it

2 is a timing diagram of a 2-phase signal including a first signal and a second signal generated by a 2-phase signal generator and a clock signal and reference signal for generating the 2-phase signal.

Referring to FIG. 2 , the clock signal CLK may be a pulse signal having a 50% duty cycle. Also, referring to FIG. 2 , the rising edge of the reference signal SE corresponding to the clock signal CLK is generated corresponding to the falling edge of the clock signal CLK, but is high during the period of the clock signal CLK. ) can be a signal that maintains the state. In addition, as the clock signal CLK has a duty cycle of 50%, the middle point of the pulse of the reference signal SE may correspond to the rising edge of the clock signal CLK.

Meanwhile, in this regard, the rising edge of the reference signal SE may occur in response to a falling edge at a specific point in time among several falling edges of the clock signal CLK, which necessarily occurs at every falling edge of the clock signal CLK. may not be necessary. In other words, the cycles of the reference signal SE and the clock signal CLK may be different.

Hereinafter, for convenience of description, a period of the clock signal CLK is referred to as T _clk , and a delay time applied to the clock signal CLK and the reference signal SE is referred to as t _rd .

Meanwhile, the plurality of delay circuits 120 delay the rising edge of the clock signal CLK once according to a delay time t _rd that is inversely proportional to the intensity of the light current. The first delay circuit 121, the reference signal It may include a second delay circuit 122 and a third delay circuit 123 for sequentially delaying the rising edge of (SE) twice according to a delay time (t _rd ) inversely proportional to the intensity of the light current. .

According to an embodiment of the present invention, the first signal AP among the two-phase signals generated by the two-phase signal generator 100 may be an output signal of the first delay circuit 121 . At this time, referring to FIG. 1, the input signal of the first delay circuit 121 is the output signal of the first gate G 1 , which is an AND gate that takes the clock signal CLK and the reference signal _SE as inputs. can

In addition, according to an embodiment of the present application, the second signal CP among the two-phase signals generated by the two-phase signal generator 100 is an opposite signal of the first signal AP and the third delay circuit 123 It may be an output signal of the second gate G ₂ , which is an AND gate that takes the output signal SEd of SEd as an input.

For reference, referring to FIG. 1 , in the above description, the opposite signal to the first signal AP is an input signal shown on the upper side of FIG. 1 among inputs applied to the second gate G ₂ , and the first signal AP ) may mean a signal obtained by applying a NOT operation.

Also, referring to FIG. 2 , both pulse widths of the first signal AP and the second signal CP may be determined as T _clk /2-t _rd . In this regard, Tclk is a period of the preset clock signal CLK, and t _rd is a delay time that is dynamically changed according to the intensity of light applied to the artificial retina device 10 and is inversely proportional to the intensity of light. It may be smaller, and may increase as the light intensity is weaker.

In addition, accordingly, the pulse widths of the first signal AP and the second signal CP generated by the two-phase signal generator 100 are determined to increase as strong light is applied to the artificial retina device 10, and the artificial retina device ( 10) is determined to be smaller as weaker light is applied, so the stimulation level (stimulation time) of the retinal stimulation site by the stimulator 200 may be determined according to the two-phase signal generated by the two-phase signal generator 100.

3 is a schematic configuration diagram of a delay circuit of a two-phase signal generator.

Referring to FIG. 3, the delay circuit 120 of the two-phase signal generator 100 delays (delays) the rising edge of the input signal (IN) but does not delay (delays) the falling edge of the output signal (OUT). It may be a circuit that generates In this regard, the delay circuit 120 mounted in the artificial retina device 10 disclosed herein may be designed to delay the rising edge of the input signal IN according to the aforementioned delay time t _rd . .

Hereinafter, the structure and function of the stimulator 200 of the artificial retina apparatus 10 will be described with reference to FIG. 4 .

4 is a schematic configuration diagram of a stimulator of a two-phase stimulation time control artificial retina device according to an embodiment of the present invention.

Referring to FIG. 4 , the stimulator 200 may include a first electrode 210 and a second electrode 220 disposed to face each other with respect to the retina stimulation site S.

The stimulator 200 may apply current in a direction from the first electrode 210 toward the second electrode 220 based on the first signal AP generated by the two-phase signal generator 100 (FIG. up arrow in 4).

Conversely, the stimulation device 200 may apply current in a direction from the second electrode 220 toward the first electrode 210 based on the second signal CP generated by the two-phase signal generator 100. (lower arrow in Fig. 4).

In addition, according to one embodiment of the present application, the stimulator 200 may include a switch that is selectively driven according to the first signal AP and the second signal CP. In other words, the stimulation device 200 may include a switch that converts a stimulation path according to the signal type of the two-phase signal applied from the two-phase signal generator 100 . In this regard, referring to FIG. 4 , the switch of the stimulator 200 generates a first signal ( ), the opposite signal of the first signal ( ), the second signal ( ), the opposite signal of the second signal ( ) may include a plurality of switch elements including NMOS switch elements or PMOS switch elements to which each input is applied.

In this regard, since the stimulator 200 is implemented as a structure including a switch, there is an advantage in that no additional bias voltage is required for the stimulator 200, and a current signal for stimulating the optic nerve of the subject's retina stimulation area is completely generated. It is determined by the resistance of the switched on.

5 is a view showing a comparison between a stimulation signal generated by a two-phase stimulation time control artificial retina device according to an embodiment of the present invention and a stimulation signal of a conventional artificial retina device.

Specifically, FIG. 5 (a) shows the intensity of light over time applied to the artificial retina system, and FIG. 5 (b) shows a stimulation signal (current signal) generated when using a conventional stimulation intensity control method. 5(c) is a stimulation signal (current signal) generated when the conventional stimulation number control method is used, and FIG. 5(d) is when using the artificial retina device 10 disclosed herein. It shows the stimulation signal based on the control of the generated pulse width/stimulus time.

Referring to FIG. 5, the artificial retina device 10 disclosed herein secures a larger stimulation dynamic range when using a conventional stimulation intensity control method (FIG. 5(b), Light-to-Amplitude Conversion) The problem of consuming a lot of static power to produce the same stimulation due to the need for a high driving voltage, and one stimulation by the stimulation frequency control method (Fig. 5 (c), Light-to-Frequency Conversion) Since a high operating frequency is required to generate a plurality of stimulation signals during a period, it can be confirmed that more efficient stimulation can be implemented by solving the problem of consuming a lot of dynamic power to generate the same stimulation.

Accordingly, in the case of the artificial retina device 10 disclosed herein, stimulation charge proportional to the light intensity is generated even at a low operating voltage, and a high operating frequency is not required, so it is possible to implement an artificial retina system that operates with lower power. There are advantages to making this possible.

6 is an exemplary view showing an artificial retina device implemented in a chip form of a two-phase stimulation time control method according to an embodiment of the present application.

Referring to FIG. 6 , the artificial retina device 10 includes a plurality of stimulator sensors including a plurality of electrodes arranged to surround a photodiode PD sensing an optical signal, arranged in a plurality of arrays. structure can be designed on a chip. Here, the plurality of electrodes (Electrode) may be designed in a form in which a pair of electrodes including the first electrode 210 and the second electrode 220 of the above-described stimulator 200 are arranged side by side.

In addition, referring to FIG. 6, the clock & sequence controller for generating and controlling the clock signal CLK and the reference signal SE of the artificial retina device 10 is the above-described stimulation sensor array. It may be disposed on the chip at a position that does not overlap with (eg, a lower side of the stimulus sensor array).

7 is a diagram showing measurement results of two-phase signals generated by an artificial retina device of a two-phase stimulation time control method according to an embodiment of the present application.

Referring to FIG. 7, the frequency of the clock signal CLK is 48 Hz, the frequency of the reference signal SE is 6 Hz, and the amplitudes of the first signal AP and the second signal CP may be set to 1 V, but , but not limited thereto, specifications of the frequency of the clock signal (CLK), the frequency of the reference signal (SE), the amplitude of the two-phase signal, etc. according to the subject's condition (age, optic nerve characteristics, etc.) according to the embodiment of the present application. It may be individualized to an appropriate value capable of providing optimal artificial retina-based stimulation to the target person.

8 is a diagram visualizing the result of adjusting the stimulation time according to the pattern of light applied to the artificial retina device of the two-phase stimulation time control method according to an embodiment of the present application.

Referring to FIG. 8, as a result of projecting light corresponding to a predetermined image to the artificial retina device 10 (Projector Image), the pulse width of the stimulation signal applied to the retinal stimulation site corresponding to the bright part of the image is It can be seen that it is larger than the dark part of .

9 is a graph showing a correlation between the intensity of light and the pulse width of a two-phase signal according to a plurality of frequencies of a clock signal.

Referring to FIG. 9 , even when the frequency of the clock signal CLK is changed to various values (eg, 32 Hz, 48 Hz, 64 Hz, etc.), the intensity of light applied to the artificial retina device 10 varies. Accordingly, it can be seen that the pulse width of the stimulation signal applied to the subject's retinal stimulation site and the stimulation time to the retinal stimulation site tend to increase well.

Hereinafter, based on the details described above, the operation flow of the present application will be briefly reviewed.

10 is an operation flowchart of a method of driving an artificial retina device of a two-phase stimulation time control method according to an embodiment of the present invention.

The driving method of the two-phase stimulation time control type artificial retina device shown in FIG. 10 may be performed by the artificial retina device 10 described above. Therefore, even if the details are omitted below, the description of the artificial retina device 10 can be equally applied to the description of the driving method of the artificial retina device of the two-phase stimulation time control method.

Referring to FIG. 10, in step S11, the two-phase signal generator 100 has a pulse width proportional to the intensity of incident light, and a first signal AP, which is a pulse signal whose high state does not overlap with each other, and a second signal AP. 2 signals (CP) can be generated.

Specifically, in step S11, the photodiode 110 may generate a photocurrent proportional to the intensity of light.

In addition, in step S11, the two-phase signal generator 100 generates the clock signal CLK or a rising edge of the reference signal SE corresponding to the clock signal CLK based on a delay time inversely proportional to the intensity of the generated photocurrent. can delay

According to an embodiment of the present application, in step S11, the two-phase signal generator 100 delays the rising edge of the clock signal CLK once according to a delay time inversely proportional to the intensity of the photocurrent, and the rising edge of the reference signal SE The first signal AP and the second signal CP may be generated by sequentially delaying the edges twice according to a delay time inversely proportional to the intensity of the photocurrent.

Next, in step S12, the stimulator 200 may alternately apply current for optic nerve stimulation to the subject's retinal stimulation site based on the first signal AP and the second signal CP generated in step S11. .

In the foregoing description, steps S11 and S12 may be further divided into additional steps or combined into fewer steps, depending on the implementation of the present application. Also, some steps may be omitted if necessary, and the order of steps may be changed.

The driving method of the artificial retina device of the two-phase stimulation time control method according to an embodiment of the present application is implemented in the form of program instructions that can be executed through various computer means and recorded on a computer readable medium. can The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on the medium may be those specially designed and configured for the present invention or those known and usable to those skilled in computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic media such as floptical disks. - includes hardware devices specially configured to store and execute program instructions, such as magneto-optical media, and ROM, RAM, flash memory, and the like. Examples of program instructions include high-level language codes that can be executed by a computer using an interpreter, as well as machine language codes such as those produced by a compiler. The hardware devices described above may be configured to act as one or more software modules to perform the operations of the present invention, and vice versa.

In addition, the driving method of the two-phase stimulation time control type artificial retina device according to an embodiment of the present application described above may be implemented in the form of a computer program or application stored in a recording medium and executed by a computer.

The above description of the present application is for illustrative purposes, and those skilled in the art will understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present application. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present application is indicated by the following claims rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts thereof should be construed as being included in the scope of the present application.

10: Two-phase stimulation time-controlled artificial retina device
100: two-phase signal generator
110: photodiode
120: retarder circuit
121: first delay circuit
122: second delay circuit
123: third delay circuit
200: stimulator
210: first electrode
220: second electrode

Claims (13)

An artificial retina device with a two-phase stimulation time control method,
a two-phase signal generator for generating a first signal and a second signal, which are pulse signals whose pulse widths are proportional to the intensity of incident light and whose high states do not overlap each other; and
A stimulator for alternately applying a current for optic nerve stimulation to a retina stimulation site of a subject based on the first signal and the second signal;
Including,
The two-phase signal generator,
a photodiode generating a photocurrent proportional to the intensity of the light; and
a plurality of delay circuits delaying generation of a clock signal or a rising edge of a reference signal corresponding to the clock signal based on a delay time inversely proportional to the intensity of the photocurrent;
That is, the artificial retina device comprising a. delete According to claim 1,
The clock signal has a duty cycle of 50%,
The rising edge of the reference signal is generated corresponding to the falling edge of the clock signal, and the reference signal is a signal that maintains a high state during a period of the clock signal. According to claim 3,
The plurality of delay circuits,
A first delay circuit that delays the rising edge of the clock signal once according to the delay time, a second delay circuit and a third delay circuit that sequentially delays the rising edge of the reference signal twice according to the delay time An artificial retina device comprising a circuit. According to claim 4,
The first signal is
The artificial retina device, which is an output signal of the first delay circuit. According to claim 5,
The artificial retina apparatus of claim 1 , wherein the input signal of the first delay circuit is an output signal of an AND gate having the clock signal and the reference signal as inputs. According to claim 5,
The second signal is
The artificial retina device of claim 1 , wherein the artificial retina device is an output signal of an AND gate having an opposite signal to the first signal and an output signal of the third delay circuit as inputs. According to claim 7,
When the period of the clock signal is T _clk and the delay time is t _rd ,
Wherein the pulse width of the first signal and the second signal is T _clk /2-t _rd , the artificial retina device. According to claim 1,
the stimulator,
Including a first electrode and a second electrode disposed to face each other with respect to the retinal stimulation site,
Applying a current in a direction from the first electrode to the second electrode based on the first signal, and applying a current in a direction from the second electrode to the first electrode based on the second signal Phosphorus, an artificial retina device. According to claim 9,
the stimulator,
The artificial retina device comprising a switch selectively driven according to the first signal and the second signal. delete delete delete

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