Artificial retina electrostimulation pixel circuit applied to visual function restoration

Abstract

The invention provides an artificial retina electrostimulation pixel circuit applied to visual function restoration, which comprises a photodiode, a capacitor C1, a Schmitt trigger, a CMOS phase inverter, a charge-discharge control loop and a stimulating electrode, wherein an anode of the photodiode is earthed, the external visible light is input of the photodiode, a cathode of the photodiode is connected with a first output end of the control loop, output of the Schmitt trigger is input of the CMOS phase inverter, an output end of the phase inverter is connected with the stimulating electrode, and the stimulating electrode serves as an output end of the pixel circuit; and an output end of the CMOS phase inverter is connected with a control end of the charge-discharge control loop, a second output end of the control loop is an input end of the Schmitt trigger, and the capacitor C1 is connected between the input end of the Schmitt trigger and the ground. The pixel circuit can remarkably improve the dynamic range of the circuit and greatly reduce the power consumption, the pulse width for the pixel circuit to output a pulse signal is fixed, the pixel area is reduced, the chip integration level is improved, and the practicability is strong.

Description

technical field [0001] The invention belongs to the field of artificial visual function restoration and optoelectronic technology, and specifically relates to an artificial retina electrical stimulation pixel circuit for visual function restoration with large dynamic range, fixed pulse width and low power consumption. Background technique [0002] Many patients who are blinded by disease of the outer retina have damage to the photoreceptors in the retina, but the optic nerve and pathways that transmit vision remain intact. If an appropriate photosensitive device is implanted in the eyes of such patients to replace the damaged photoreceptors in the retina, the electrical signal generated by the photosensitive device is used to stimulate the nerve cells in the retina, and the optic nerve transmits the nerve impulse generated by the electrical stimulation to the visual cortex (optic nerve). Center), so that patients blinded by retinal diseases can experience light, and their vi...

AI Technical Summary

Problems solved by technology

[0003] In recent years, many countries have been conducting research on artificial visual function restoration, but these artificial retinal circuits have obvious shortcomings: first, the dynamic range of the circuit is small, the range of light intensity that can be felt is small, and the practicability is relatively poor; The second is that the pulse width of the circuit output signal increases with the increase of the incident light intensity, which intensifies the nonlinearity between the optic nerve stimulation signal intensity and the incident light intensity, causing serious visual distortion; the third is that the power consumption of the pixel is large , large area, which is not conducive to the development of artificial retinal circuits in the direction of large-scale integration and radio frequency energy transmission

For example CN100391558C discloses " the electrical retinal stimulation pixel circuit that is used for artificial vision restoration ", owing to adopting the CMOS inverter with Schmidt trigger function and simple feedback loop, the circuit structure is unreasonable, and its dynamic range is little ( It is only about 30dB), and it cannot work normally when the light is strong; the pulse width of the output signal is not fixed, which will cause the nonlinear distortion of the vision of the blind person whose artificial vision function is repaired; the power consumption is relatively large (2uW / pixel), and it is used to form The power consumption of the 160×120 array is 38.4mW. When the array is installed in the eyes of the blind, it will generate heat and affect the health of the blind.

Due to the above problems, the practicability of this circuit is relatively poor

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