JP2006068404A - Artificial eye system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an artificial eye system comprising an efficient power transmitting means for electrically stimulating the retina of a blind patient with low power consumption, applicable to patients at various levels of disorder. <P>SOLUTION: The artificial eye system is implanted in an eyeball of the patient for detecting the light on the retina of the eyeball and transmitting the intensity of the detected light to the retina of the eyeball as a stimulative electric current. The artificial eye system is characterized by the control of the operation of the system by the kinetic motion of the eyelid. The artificial eye system consists of an extraocular device and an intraocular device. The extraocular device comprises a transmitter and a primary coil, and the intraocular device comprises a secondary coil, a signal transmitting circuit, a bias control circuit, and a stimulative current generating circuit. The secondary coil is connected to the signal transmitting circuit, and the bias control circuit controls the stimulative current generating circuit with the output of the signal transmitting circuit. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an artificial eye system that electrically stimulates the retina of a blind patient, and more particularly, to an artificial eye system that can be applied to patients of various disease levels and has low power consumption.

    There is a growing interest in artificial visual instruments that electrically stimulate the retina of a blind patient suffering from a late-stage photoreceptor degenerative disease and replace the eye. In this artificial visual device, it is necessary to adjust parameters (for example, frequency, amplitude, pulse width, and pulse interval) of the stimulation current waveform in accordance with the degree of retinal damage of the patient. These contents are shown in detail in Non-Patent Document 1 and Non-Patent Document 2, for example.

However, the intraocular device is required to keep power consumption as low as possible in consideration of power transmission and heat generation. However, the methods shown in these documents sufficiently show the solution. Not.
W. Liu, et al., IEEE J. Solid-State Circuits 35 (2000) 1487 MS Humayun, et al., Vision Res. 39 (1999) 2569.

  As described above, the conventional artificial eye system can control the waveform parameter of the biographical stimulus given to the retina, but has a problem in power consumption.

  It is an object of the present invention to provide an artificial eye system that includes an efficient power transmission means and achieves low power consumption.

  According to the present invention, in an artificial eye system that is embedded in an eyeball, detects light on the retina in the eyeball, and transmits the detected light intensity to the retina in the eyeball as a stimulation current, the system operation is controlled by eyelid movement. A characteristic artificial eye system is obtained.

  In addition, the present invention is configured by an extraocular device and an intraocular device as a specific configuration. The extraocular device includes a transmitter and a primary coil, and the intraocular device includes a secondary coil, a signal transmission circuit, a bias control circuit, and a stimulation current generation circuit, and the secondary coil is connected to the signal transmission circuit and biased. The control circuit provides the artificial eye system, wherein the stimulation current generation circuit is controlled by the output of the signal transmission circuit.

  According to the present invention, a new signal transmission circuit (telemetry circuit) that is controlled by human eyelid movement is used by using a CMOS technology having a light detection function and a low power consumption circuit function at the same time as a stimulation current generation circuit for an artificial eye. Since it used, the effect that the artificial eye system of the low power consumption which can be utilized without difficulty for a patient can be provided is acquired.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The block diagram of the artificial eye system and its conceptual diagram are shown in Figs. This system comprises an extraocular device 1 and an intraocular device 2 connected by electromagnetic induction.
The extraocular device 1 comprises a transmitter 4 having a primary coil 3.
The intraocular device 2 includes a secondary coil 5 and a three-dimensional structure artificial eye chip 10. Specifically, the intraocular device 2 includes a pixel coil 8 including a secondary coil 5, a signal transmission (telemetry) circuit 6 controlled by a human eyelid movement, a bias control circuit 7, and a stimulation current generation circuit 9.

  A conceptual diagram of the artificial eye system shown in the block diagram of FIG. 1 is as shown in FIG. The three-dimensional structure artificial eye chip 10 shown in the block diagram includes a photodetector 11, an imaging circuit 12, a vertical wiring 13, a stimulation current generation circuit 9, a signal transmission (telemetry) circuit 6, and an electrode array 14 in its structure. Including. The three-dimensional artificial eye chip 10 is an LSI chip having a CMOS multilayer structure, and has a feature of having a light detection function and a low power consumption circuit function at the same time. In addition, by adopting a multilayer wiring structure, downsizing is realized, and a form that can be easily taken into a patient's living body is realized.

The intraocular device 2 is required to keep power consumption as low as possible in consideration of power transmission and heat generation.
To satisfy this requirement, two states are set for the intraocular device 2. It is in the state of “EDIT” and “RUN”.

First, the “EDIT” state will be described. When the patient closes the eyelid, the intraocular device 2 transitions to the “EDIT” state. At this time, since the stimulation current generation circuit 9 hardly generates a pulse of stimulation current, the power consumption of the intraocular device 2 is reduced. The signal transmission (telemetry) circuit 6 takes in a data signal from the transmitter 4 in the “EDIT” state. Therefore, the signal transmission (telemetry) circuit 6 does not operate simultaneously with the stimulation current generation circuit 9.
Details of these circuits will be described with reference to FIGS.

As shown in FIG. 3, the bias control circuit 7 includes a main control unit 15, a synchronization circuit 16, a register 17, a bias generation circuit 18, and a DAC (digital analog converter) 19.
The DAC 19 supplies a bias voltage according to the bit data transmitted from outside the eye and stored in the register 17. Thereby, the bias voltage supplied to the stimulation current generation circuit 9 is controlled from outside the eye to adjust the stimulation current waveform parameter.

Next, the operation of the signal transmission (telemetry) circuit 6 which is the main point of the present invention will be described.
The signal transmission (telemetry) circuit 6 is controlled by a human eyelid movement, and its block diagram is shown in FIG. The configuration consists of a power recovery circuit 20, a clock / data recovery circuit 21, and a human eyelid movement detector (DHEM) 22.

  When the patient closes the eyelid, the stimulation current generation circuit 9 hardly generates stimulation current pulses, so that the power consumption of the intraocular device 2 is reduced. During this “EDIT” state, the clock / data recovery circuit 21 receives the clock signal and the bit data, and stores the bit data in the register 17.

Conversely, the stimulation current generation circuit 9 generates stimulation current pulses while the patient opens the eyelid. The stimulation current generation circuit 9 is constituted by an analog asynchronous circuit that does not require a clock signal, and is controlled by bit information stored in the register 17.
These operating states while the patient opens the eyelids are referred to as “RUN” states, and during this “RUN” state, the power supplied to the clock / data recovery circuit 21 is disconnected, so that the intraocular device 2 Power consumption can be reduced.

FIG. 5 shows a detailed circuit of the DHEM 22. The DHEM 22 senses light incident on the artificial eye to detect human eyelid movement, and controls the “EDIT” and “RUN” states.
In order to prevent confusion between the blinking state and the closed state, the time constant of the DHEM 22 is set to be larger than the blinking time (approximately 100 ms).
The stimulation current generation circuit 9 can be formed into an LSI using, for example, 0.35 μm, 2-layer polysilicon, 3-layer metal CMOS technology.

FIG. 6 shows a detailed circuit diagram of the stimulation current generation circuit 9 having a light detection function. FIG. 7 shows the result of measuring an LSI with this configuration, which shows that this circuit can detect incident light and convert the illuminance information into bipolar stimulation current pulses. FIG. 8 shows the characteristic of the bias voltage (BIAS2) of the negative current pulse width (Cathodic Pulse Width) of the negative electrode. By controlling the bias voltage (BIAS2) as shown in FIG. 8, the negative current pulse width of the negative electrode can be adjusted from about 0.5 ms to 5 ms. In addition, the bias voltage (BIAS5,
By controlling BIAS4), the positive current pulse width of the positive electrode can be controlled, and the current pulse interval between the two electrodes can be adjusted from about 0.5 ms to 5 ms.
In order to improve the stability of the system, a mechanism for stable operation immediately after power-on is indispensable. In the artificial eye system of the present invention, when the power is turned on, the standby mode is automatically entered first. Next, when the data for operation is sent, the mode is shifted to the operation mode, and the operation described above is started based on the instruction of the input data. This prevents the system from running away when the power is turned on.

  As described above, the artificial eye system according to the present invention has a new signal transmission (telemetry) circuit controlled by a human eyelid movement. In this system, a signal is transmitted during a period when the patient opens the eyelid. The power supplied to the transmission (telemetry) circuit is disconnected. As a result, the power consumption of the intraocular device can be reduced, and a small artificial eye system with less heat generation can be configured. Further, since the stimulation current generation circuit mounted on the prototype chip can generate the stimulation current pulse without using the clock signal, it can be configured to be of a lower power consumption type.

  On the other hand, by controlling the bias voltage, the current pulse width of the stimulation current and the current pulse interval between the bipolar electrodes can be adjusted from about 0.5 ms to 5 ms, enabling the construction of an artificial eye system that can be applied to patients with a wide range of symptoms. It is.

  The artificial eye system according to the present invention can be applied to the field of artificial vision devices for blind patients suffering from terminal photoreceptor degenerative diseases.

  In particular, parameters (eg, frequency, amplitude, pulse width, and pulse interval) of the stimulation current waveform can be easily adjusted according to the degree of retinal damage of the patient, and can be widely used according to the patient's symptoms. I can do it.

Conceptual block diagram of an artificial eye system Conceptual diagram of an artificial eye system Bias control circuit Signal transmission (telemetry) circuit block diagram DHEM detailed circuit Detailed circuit of stimulation current generation circuit Operation diagram of stimulation current generator circuit Bias voltage vs. negative current pulse width characteristics

Explanation of symbols

1 Ocular device
2 Intraocular devices
3 Primary coil
4 Transmitter
5 Secondary coil
6 Signal transmission circuit
7 Bias control circuit
8 pixel circuit
9 Stimulation current generation circuit
10 Three-dimensional structure artificial eye chip
11 Light detector
12 Imaging circuit
13 Vertical Wiring 14 Electrode Array 15 Main Control Circuit 16 Synchronous Circuit 17 Register 18 Bias Generation Circuit 19 DAC
20 Power regeneration circuit
21 Clock data recovery circuit 22 Human eyelid movement detector (DHEM)

Claims (10)

  In an artificial eye system that is embedded in an eyeball, detects light on the retina in the eyeball, and transmits the intensity of the detected light to the retina in the eyeball as a stimulation current, system operation is controlled by eyelid movement Artificial eye system.     The artificial eye system includes an extraocular device and an intraocular device, and the extraocular device includes a transmitter and a primary coil, and the intraocular device includes a secondary coil, a signal transmission circuit, and a bias control circuit. 2. The stimulation current generation circuit according to claim 1, wherein the secondary coil is connected to the signal transmission circuit, and the bias control circuit controls the stimulation current generation circuit according to an output of the signal transmission circuit. Artificial eye shim tem.     The operation controlled by the eyelid movement is configured in the signal transmission circuit, and includes a human eyelid movement detector and a clock data recovery circuit controlled by the output of the human eyelid movement detector. The artificial eye system according to claim 2, wherein operation of the stimulation current generation circuit is controlled.   4. The artificial eye system according to claim 3, wherein in the human eyelid movement detector, the detection time of closure is set to 100 ms or more.   The artificial eye system according to claim 2, wherein the stimulation current generation circuit converts the intensity of the detected light into a bipolar current pulse.   The bipolar current pulse in the stimulation current generation circuit can control the pulse width of the positive current pulse and the pulse width of the negative current pulse, and can control the generation interval of the positive current pulse and the negative current pulse. The artificial eye system according to claim 5.     Control of the pulse width of the positive current pulse, control of the pulse width of the negative current pulse, and control of the generation time interval of the positive current pulse and the negative current pulse of the current pulse of the bipolar electrode in the stimulation current generation circuit, The artificial eye system according to claim 6, which is performed by an output of the bias control circuit.     The artificial eye system according to claim 2, wherein the bias control circuit includes a register and a DAC (digital analog converter) that receives the register output, and the DAC output is used as the bias control circuit output.   9. The artificial eye system according to claim 8, wherein the register receives a signal transmitted from the communication device in the extraocular device, generates bit data, and outputs the bit data to the DAC. 2. The artificial eye shim system according to claim 1, wherein when the system is turned on, first, the operation input data standby mode is set, and the operation based on the operation input data is started after the operation input data is obtained.