CN100444812C - Intraocular camera for visual prosthesis - Google Patents

Abstract

An intraocular camera used for visual prosthesis belongs to the technical field of medical instruments. In the present invention, the gradient refractive index lens and the CMOS image sensor are seamlessly connected, and the annular solar cell completely wraps the gradient refractive index lens and the CMOS image sensor inside, and the annular solar cell is connected with the CMOS image sensor to provide stable power for the CMOS image sensor. Operating Voltage. As an optical lens, the gradient index lens has a short focal length, which can realize seamless connection with the CMOS image sensor and reduce the axial size of the system. The designed low-pixel CMOS image sensor not only reduces the size but also reduces power consumption while meeting the requirements of object recognition. Powered by annular solar cells, it is safe and has no toxic side effects on the human body, and once implanted, the trouble of replacing the battery is eliminated. The annular design conforms to the shape of the human pupil, and its small size facilitates implantation.

Description

Intraocular camera for visual prosthesis

technical field

The invention relates to a device in the technical field of medical equipment, in particular to an intraocular camera for visual prosthesis.

Background technique

In recent years, many camera systems using solid-state imaging elements have been developed, which can collect image information in real time and are widely used in medical treatment, monitoring, security, etc. However, in order to meet the needs of various applications, they usually have high pixels and high resolution, complex functions, large size, and high power consumption, which cannot meet the requirements of visual prostheses.

Existing camera systems usually use common lenses as optical lenses, which have a long focal length and large size, are difficult to process, are inconvenient to implant, and have high production costs.

At present, button batteries are usually used as power sources in miniature imaging devices, which are small in size and easy to implant. But its weak point is: the button battery contains harmful substances to the human body, it is obviously inappropriate to stay in the human body for a long time, and when the battery is exhausted, it is more troublesome to replace the battery.

Found through document retrieval to prior art, Chinese invention patent application number is CN03262832.3, and the disclosure date is September 15th, 2004, and this patent self-statement is: " miniature camera, it is made up of optical lens, camera, is characterized in that : The optical lens is a self-focusing lens, the front end of the self-focusing lens is a plane, the rear end is a spherical surface, the imaging surface of the self-focusing lens has a CCD camera, and the front end of the self-focusing lens is fixed with a small hole diaphragm vertically to the optical axis. The disadvantages are: 1. CCD camera is used as the imaging device, 2. The self-focusing lens (that is, the gradient index lens) does not consider shortening the focal length to achieve seamless connection with the CCD, so the system is only miniaturized to a certain extent , but for the needs of the camera in the eye of the visual prosthesis, the system is obviously too large and not easy to implant. And the system does not take into account the power design part.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, and propose an intraocular camera for visual prosthesis, which has small size and low power consumption, meets the needs of visual prosthesis imaging, and can be implanted in the eye, through The rotation of the human eyeball automatically realizes the scanning.

The present invention is achieved through the following technical solutions. The intraocular camera for visual prosthetics described in the present invention includes: a gradient refractive index lens, a CMOS (complementary metal oxide semiconductor) image sensor, and a ring-shaped solar cell. The gradient index lens and the CMOS image sensor are seamlessly connected, and the annular solar cell completely wraps the gradient index lens and the CMOS image sensor inside to form an overall system. The annular solar cell is connected with the CMOS image sensor to provide a stable working voltage for the CMOS image sensor.

The gradient index lens has a diameter between 0.35mm-0.6mm and a length between 1.3mm-3mm. The gradient index lens is used as an optical lens to cover the front surface of the photosensitive array in the CMOS image sensor, providing it with Gather light. The graded index lens adopts graded index fiber, which is small in size, short in focal length, and easy to install. It can realize seamless connection with CMOS image sensor, further reduces the axial size of the camera system, and facilitates intraocular implantation.

The CMOS image sensor includes: a photosensitive array, a control circuit, a preprocessing circuit, and an analog-to-digital conversion (A/D) circuit. The output of the control circuit is connected to the signal input end of the photosensitive array, the signal output end of the photosensitive array is connected to the input end of the preprocessing circuit, the output end of the preprocessing circuit is connected to the analog-to-digital conversion circuit, and the control circuit generates a control signal to the photosensitive array. After photoelectric conversion, the photosensitive array outputs an electrical signal proportional to the light intensity. The signal is first output to the preprocessing circuit, and the processed analog signal is output to the analog-to-digital conversion circuit. After the analog-to-digital conversion, the digital signal is output.

The photosensitive array has a resolution of 25×25, a total number of pixels of 625, a size range of the smallest image sensitive unit between 6um×6um-10um×10um, and a photosensitive area of 0.15mm×0.15mm-0.25mm×0.25mm between. The basic component of the photosensitive array, that is, the image sensitive unit, adopts an active structure, and there is no color filter on the surface of the pixel, that is, only gray value signals are generated. The designed low-pixel CMOS image sensor, on the basis of meeting the requirements of object recognition, not only reduces the size, but also reduces power consumption, which is convenient for intraocular implantation. The dimensions of the CMOS image sensor are between 0.25mm×0.25mm-0.45mm×0.45mm, the diagonal size is between 0.35mm-0.6mm, and the thickness is between 0.3mm-0.6mm. The frame frequency is between 24fps-30fps, the working voltage is 2.5V, the power consumption is between 0.5mW-1.0mW, and an 8-bit digital signal is output.

The annular solar cell has an inner diameter of 0.35mm-0.6mm, an outer diameter of 4.0mm-8.0mm, a thickness of 1.6mm-3.6mm, a conversion efficiency of 15%-23%, and an output power of up to 1mW. A ring-shaped solar cell is wrapped around the gradient-index lens and the CMOS image sensor as a circumscribed circle, providing it with a stable 2.5V operating voltage. The solar cell is designed in a ring shape, and its circular inner edge is convenient for wrapping the cylindrical gradient index lens; and the human pupil is circular, and the smooth outer edge of the solar cell is more suitable for implanting in the pupil. The small size and self-charging feature facilitate the intraocular implantation of the system, and eliminate the hassle of battery replacement once implanted.

In the present invention, the diameter of the gradient index lens is between 0.35mm and 0.6mm, and the diagonal length of the CMOS image sensor is between 0.35mm and 0.6mm. The design ensures that the two dimensions are completely consistent, seamlessly joined, and the annular solar cell The inner diameter is between 0.35mm-0.6mm, ensuring that it is exactly the same as the diameter of the gradient index lens and the length of the diagonal of the CMOS image sensor, so that it is completely wrapped around the gradient index lens and the CMOS image sensor in the form of a circumscribed circle. It not only protects the gradient index lens, but also provides packaging to form an overall system. The maximum size of the present invention is limited to an outer diameter of 8.00mm and a length of 3.6mm, and a minimum outer diameter of 4.0mm and a length of 1.6mm. According to the size of the human pupil, it can be seen that the system can be implanted in the eye to realize the camera function.

Description of drawings

FIG. 1 is a schematic structural diagram of an intraocular camera used in a visual prosthesis according to the present invention.

Fig. 2 is a cross-sectional view of the intraocular camera used in the visual prosthesis of the present invention.

Fig. 3 is a structural block diagram of a CMOS image sensor in the present invention.

FIG. 4 is a structural diagram of a photosensitive array of a CMOS image sensor in the present invention.

Detailed ways

As shown in FIG. 1 , the intraocular camera for visual prosthesis of the present invention includes: a gradient index lens 1 , a CMOS image sensor 2 , and a ring-shaped solar cell 3 . The gradient index lens 1 and the CMOS image sensor 2 are seamlessly connected, and the annular solar cell 3 completely wraps the gradient index lens 1 and the CMOS image sensor 2 inside, and the annular solar cell 3 is connected with the CMOS image sensor 2, forming a CMOS image sensor 2 Provide a stable working voltage.

As shown in Figure 2, the diameter of the gradient index lens 1 is between 0.35mm-0.6mm, and the diagonal size of the CMOS image sensor 2 is between 0.35mm-0.6mm, so that the two dimensions are exactly the same and seamlessly joined together , the inner diameter of the annular solar cell 3 is between 0.35mm-0.6mm, which is exactly the same as the diameter of the gradient index lens 1 and the size of the diagonal of the CMOS image sensor 2, as a circumscribed circle, completely wrapped outside, and implanted into the pupil as a whole internal. The thickness of the CMOS image sensor 2 is between 0.3mm-0.6mm, the length of the gradient index lens 1 is between 1.3mm-3mm, and the thickness of the annular solar cell 3 is between 1.6mm-3.6mm. The length of 3 is equal to the sum of the length of the gradient index lens 1 and the thickness of the CMOS image sensor 2, so that it can completely wrap the gradient index lens 1 and the CMOS image sensor 2 inside, which is convenient for installation and implantation.

According to the calculation of the model eye, assuming that the expected restored visual acuity is 0.1, the minimum pixel size of the CMOS image sensor 2 should not be less than 6um. The larger the pixel size, the stronger the ability to capture light and the better the image quality, but the more difficult it is to manufacture, and the higher the production cost. Taking into account, the minimum pixel size range for designing a CMOS image sensor 2 is between 6um×6um-10um×10um between.

Studies have shown that for the blind, only 25×25, that is, 625 total pixels, can recognize objects. In this way, the photosensitive array of the CMOS image sensor 2 is designed to be 25×25, and the lower number of pixels not only reduces the size of the image sensor 2, but also reduces its power consumption. In the initial stage of research, a lower number of pixels was selected. If the requirements increase in the future, the pixels of the image sensor can be further increased. At the same time, in the initial stage of research, only black and white images are considered, so there is no color filter on the surface of the image sensitive unit, and the gray value image is output.

After calculation, the photosensitive area of the CMOS image sensor is between 0.15mm×0.15mm-0.25mm×0.25mm, plus some other internal processing circuits, it is expected that the size of the CMOS image sensor 2 will be limited to 0.25mm×0.25mm-0.45mm mm×0.45mm, the diagonal size is between 0.35mm-0.6mm, and the thickness is between 0.3mm-0.6mm.

According to human physiological characteristics, when the image refresh rate reaches 5fps, people begin to feel that the image is active; when it reaches 24fps, people feel that the image is completely continuous and smooth, and the frame rate used in movies is 24fps, so the video signal The frame rate should be greater than or equal to 24Hz. Theoretically, the higher the frame rate, the better, but the higher the frame rate, the higher the requirements for the circuit, the more complex the technology, the higher the difficulty of post-processing, and the higher the cost. In the case of comprehensive consideration, the design of CMOS image sensor 2 The frame rate is between 24fps-30fps. In this case, the data transmission rate is about 1.9Mbit/s (considering that the output is an 8-bit digital signal at 30fps).

As shown in FIG. 3 , the functional modules of the CMOS image sensor include: a photosensitive array, a control circuit, a preprocessing circuit, and an analog-to-digital conversion A/D circuit. Among them, the photosensitive array is the core of the image sensor, which performs photoelectric conversion on the image information and outputs electrical signals. The control circuit completes functions such as horizontal and vertical control, timing circuit generation, and automatic exposure control, so that the image sensor can output images at a certain timing. The preprocessing circuit performs preliminary processing on the output analog signal, including functions such as automatic gain control and filtering. The analog-to-digital conversion A/D circuit performs digital conversion on the processed analog signal, and outputs an 8-bit gray value digital signal. The control circuit generates some control signals to the photosensitive array, and the photosensitive array performs photoelectric conversion under certain control to output an electrical signal proportional to the light intensity. The signal is first output to the preprocessing circuit, and the processed analog signal is output to the modulus The conversion circuit outputs digital signals after performing analog-to-digital conversion.

As shown in Figure 4, the photosensitive array in the described CMOS image sensor 2 includes: 25H*25V total number of pixels, its image sensitive units are arranged in a square matrix of 25H*25V according to the X and Y directions, each of the square matrix The image sensitive unit has its address in X and Y directions, which can be selected by horizontal and vertical controls respectively. The image sensor unit adopts an active structure, that is, the active image sensor unit structure. After each image sensor unit is amplified, it is output through the field effect transistor analog switch, the fixed pattern noise is greatly reduced, and the signal-to-noise ratio of the image signal is significantly improved. . In the visual prosthesis, only black and white images are required, so there is no need to cover the surface of the image sensitive unit with a color filter, and the gray value signal can be directly output to obtain a black and white image.

The difference between the gradient index lens 1 and the ordinary lens is: 1. It can not only refract the light transmitted along the radial direction, but also its refractive index distribution gradually decreases along the radial direction, which can realize the smooth and continuous convergence of the outgoing light 2. High light transmission efficiency, easy to process, smooth planes at both ends, easy to install; 3. Small diameter, small overall size, and short focal length up to 0.5mm, easy to implant into the eye.

It is required here that the gradient index lens 1 has an external dimension, the diameter is consistent with the diagonal dimension of the CMOS image sensor 2, between 0.35mm-0.6mm, the length is between 1.3mm-3mm, the numerical aperture is 0.46, and the intercept is 0.25P . When the intercept 0.25P is selected, the parallel rays incident from the front face of the lens converge to the rear end face of the lens through the self-focusing lens, and the CMOS image sensor 2 is directly installed on the rear end face, which can shorten the axial dimension of the intraocular camera.

Since the energy provided by the solar cell is limited, the power consumption of the CMOS image sensor 2 must be reduced as much as possible. Therefore, the sensor adopts a low working voltage of 2.5V, and the internal circuit structure is simple, which can limit its power consumption between 0.5mW-1mW to achieve low power consumption.

The solar battery is small in size, easy to implant, and can be automatically charged. After implanting in the eye, the trouble of replacing the battery can be avoided. It has no toxic side effects, is safer, and has little harm to the human body. At present, the conversion efficiency of ordinary monocrystalline silicon solar cells is 15%, and the conversion efficiency in the laboratory can reach 23%. The diagonal size of the CMOS image sensor 2 is between 0.35 mm and 0.6 mm, and the size of the ring-shaped solar cell 3 is designed to be such that the inner diameter is exactly the same as the diameter of the gradient index lens 1 and the diagonal length of the CMOS image sensor 2, at 0.35 mm. mm-0.6mm, the outer diameter is between 4.0mm-8.0mm, the thickness is equal to the sum of the length of the gradient index lens 1 and the thickness of the CMOS image sensor 2 during design, and it is between 1.6mm-3.6mm, In this way, its output power can reach 1 mW, which meets the working requirements of the CMOS image sensor 2 . It is designed in a ring shape, the inner circle is convenient for combination installation with the gradient index lens 1 and the CMOS image sensor 2 , and the smooth edge of the outer circle is convenient for transplantation into the eye. At the same time, its thickness can completely wrap the gradient index lens 1 and the CMOS image sensor 2 inside, which not only plays a role of protection, but also provides packaging to form an overall system.

Claims (6)

1. intra-ocular camera head that is used for vision prosthesis, comprise: gradient-index lens (1), cmos image sensor (2), annular solaode (3), it is characterized in that, gradient-index lens (1) and cmos image sensor (2) seamless combination, annular solaode (3) is wrapped in annular solaode (3) inside fully with gradient-index lens (1) and cmos image sensor (2), annular solaode (3) is connected with cmos image sensor (2), for cmos image sensor (2) provides stable running voltage.

2. the intra-ocular camera head that is used for vision prosthesis according to claim 1, it is characterized in that, described gradient-index lens (1), the Diagonal Dimension of diameter and cmos image sensor (2) is in full accord, between 0.35mm-0.6mm, length between 1.3mm-3mm, numerical aperture 0.46, intercept 0.25P.

3. the intra-ocular camera head that is used for vision prosthesis according to claim 1, it is characterized in that, described cmos image sensor (2), comprise: photosensitive array, control circuit, pre-process circuit, analog to digital conversion circuit, the output of control circuit is connected to the signal input part of photosensitive array, the signal output part of photosensitive array is connected to the input of pre-process circuit, the outfan of pre-process circuit is connected to analog to digital conversion circuit, control circuit produces control signal and gives photosensitive array, photosensitive array carries out exporting and the proportional signal of telecommunication of light intensity after the opto-electronic conversion, this signal at first outputs to pre-process circuit, analogue signal is after treatment exported to analog to digital conversion circuit, carries out exporting digital signal after the analog digital conversion.

4. the intra-ocular camera head that is used for vision prosthesis according to claim 3, it is characterized in that, described photosensitive array, its resolution is 25 * 25, total pixel number 625, and the quick unit size scope of statuette is between 6 μ m * 6 μ m-10 μ m * 10 μ m, photosensitive area is between 0.15mm * 0.15mm-0.25mm * 0.25mm, the quick unit of picture adopts active structure, does not have the colored filter of covering on the pixel surface, promptly only produces the gray value signal.

5. according to claim 1 or the 3 described intra-ocular camera heads that are used for vision prosthesis, it is characterized in that, described cmos image sensor (2), its overall dimensions is between 0.25mm * 0.25mm-0.45mm * 0.45mm, and Diagonal Dimension is between 0.35mm-0.6mm, and thickness is between 0.3mm-0.6mm, frame frequency is between 21fps-30fps, running voltage 2.5V, power consumption is exported 8 position digital signals between 0.5mW-1.0mW.

6. the intra-ocular camera head that is used for vision prosthesis according to claim 1, it is characterized in that, described annular solaode (3), the Diagonal Dimension of the diameter of its internal diameter and gradient-index lens (1) and cmos image sensor (2) is in full accord, between 0.35mm-0.6mm, external diameter is between 4.0mm-8.0mm, the thickness sum of guaranteeing the length of its thickness and gradient-index lens (1) and cmos image sensor (2) is consistent, between 1.6mm-3.6mm, conversion efficiency 15%-23%, output can reach 1mW.

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