JP2010239844A - Power transmission circuit, and vision reproduction auxiliary device equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power transmission circuit capable of effectively transmitting power. <P>SOLUTION: The power transmission circuit transmits the power output from a power amplifier with a constant voltage amplitude, by using a coil link formed by a primary circuit having a primary coil and a secondary circuit having a secondary coil. The primary circuit has the primary coil, a first reactance connected in series to the primary coil, the power amplifier with the constant voltage amplitude, and a second reactance connected in parallel to the power amplifier. The first reactance is designed to be constant in the power at the secondary circuit with respect to a minimal distance and a maximal distance between the primary coil and the secondary coil designed preliminarily. The second reactance is designed to be smaller in the peak value of the power amplifier, when the distance between the coils changes from the minimal distance to the maximal distance to improve the power factor of the power amplifier. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a power transmission circuit that transmits power from a primary side to a secondary side by a coil link. The present invention also relates to a visual reproduction assisting device that reproduces part or all of a patient's vision using a power transmission circuit.

2. Description of the Related Art Conventionally, a technique is known in which coils are installed in different units and power is supplied to the other unit in a non-contact manner by a power transmission circuit using a coil link (see, for example, Patent Document 1).
In addition, as an apparatus using such a power transmission circuit, an electrode array is implanted in the body of an eyeball or the like, and cells that form vision are stimulated by electrical stimulation pulses from the electrodes, so that one of the lost visual functions is obtained. A visual reproduction assisting device that substitutes a part is known (for example, see Patent Document 2). Such a visual reproduction assisting device includes an in-vivo device installed in the body and an extracorporeal device worn by the user. The internal device is provided with an electrode for electrically stimulating cells constituting the retina and a control unit including an integrated circuit for controlling the electrode. The external device includes a power source for storing power to be supplied to the internal device, And a control unit that generates stimulation information and the like to the apparatus. The intracorporeal device and the extracorporeal device each include a primary coil (external device side) and a secondary coil (intracorporeal device side), and perform power transmission and information transmission using a coil link.

JP-A-11-188113 JP 2004-298298 A

  In the visual reproduction assisting device as shown in Patent Document 2, for example, the secondary coil is implanted in the temporal region, the primary coil is positioned above the secondary coil through the skin of the head, Since the configuration is such that the coil link is performed, the positional relationship between the primary coil and the secondary coil may be shifted depending on the use situation, and the distance between the coils may change. In addition, the installation state of the coils is likely to vary depending on the thickness of the user's skin and the mounting location. For this reason, in order to supply power stably, a method is conceivable in which the amount of power transmitted from the primary coil side is increased in advance assuming a state in which power transmission efficiency is poor. However, in such a method, even when the transmission efficiency is in a good state, more power than necessary is supplied, and the power efficiency cannot be improved. In particular, in a device used in the body such as a visual reproduction assisting device, it is desired to suppress the generation of heat as much as possible to increase the power efficiency.

  In view of the problems of the above-described conventional technology, it is an object of the present invention to provide a power transmission circuit capable of efficiently performing power transmission, and further to provide a visual reproduction auxiliary device including such a power transmission circuit. .

In order to solve the above problems, the present invention is characterized by having the following configuration.
(1) In a power transmission circuit that transmits power output from a power amplifier having a constant voltage amplitude using a coil link of a primary side circuit having a primary coil and a secondary side circuit having a secondary coil. The primary side circuit includes the primary coil, a first reactance connected in series to the primary coil, the power amplifier, and a second reactance connected in parallel to the power amplifier. The first reactance is designed so that the power of the secondary side circuit is the same with respect to a minimum distance and a maximum distance between the primary coil and the secondary coil that are temporarily set; Is designed to reduce the power peak of the power amplifier when the distance between the coils changes from the minimum distance to the maximum distance in order to improve the power factor of the power amplifier. The
(2) In the power transmission circuit of (1), the magnitude of the reactance of the first reactance is capacitive and is designed to be larger than the magnitude of the inductance of the primary coil. And
(3) In the power transmission circuit of (2), the second reactance is a coil.
(4) In the power transmission circuit according to any one of (1) to (3), the voltage amplitude of the power amplifier is modulated during transmission from the primary side circuit to the secondary side circuit.
(5) A visual reproduction assisting device that reproduces all or part of a patient's vision includes the power transmission circuit according to any one of (1) to (4).

  According to the present invention, power transmission can be performed efficiently.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing the appearance of a visual reproduction assisting device (external device) according to one embodiment, and FIG. 2 is a diagram showing an in-vivo device in the visual reproduction assisting device.

  As shown in FIGS. 1 and 2, the visual reproduction assisting device 1 includes an extracorporeal device 10 for photographing the outside world, and an in-vivo device 20 that promotes visual reproduction by applying electrical stimulation to cells constituting the retina. The extracorporeal device 10 includes a visor 11 on which a patient is placed, an imaging device 12 including a CCD camera or the like attached to the visor 11, an external device 13, a primary coil 14 serving as transmission means, and the like.

  The external device 13 is provided with data modulation means 13a having an arithmetic processing circuit such as a CPU, and a battery 13b as a power source for the visual reproduction assisting device 1. The modulation unit 13a performs processing for acquiring an image photographed by the photographing device 12, performing image processing, and generating data for electrical stimulation pulses for reproducing vision. The modulation means 13a transmits electrical stimulation pulse data and power for driving the internal apparatus 20 described later as electromagnetic waves to the internal apparatus 20 via the primary coil 14 connected to the modulation means 13a (wirelessly). Send. Here, the modulation means 13a uses electric power as a carrier wave, and superimposes information such as electrical stimulation pulse data, which is a control signal, on the carrier wave by amplitude modulation (this signal is defined as a drive signal). A magnet (not shown) is attached to the center of the primary coil 14. The magnet is used to fix the position with a transmission / reception means (secondary coil) 31 described later. An imaging device 12 is attached to the front surface of the visor 11 in the shape of glasses, and is used in front of the patient's eyes.

  The in-vivo device 20 shown in FIG. 2 is roughly divided into a receiving unit 30 for receiving electrical stimulation pulse signal data and power transmitted from the extracorporeal device 10 by electromagnetic waves, and a tissue constituting the visual nervous system that forms the vision of the patient. It is comprised by the stimulation part 40 for electrically stimulating the cell which comprises the retina which is. The receiving unit 30 has a function of receiving a driving signal (including information used by the in-vivo device 20) from the outside (external device 10). The receiving unit 30 is provided with a control unit 100 including a secondary coil 31, a control circuit 32, and a receiving circuit 302 that are receiving means for receiving electromagnetic waves from the extracorporeal device 10. The control circuit 32 generates an electrical stimulation pulse signal for obtaining vision based on the electrical stimulation pulse data and power obtained through the secondary coil 31, and an electrode designation signal for designating an electrode corresponding to this signal. , Has a role as a control means for transmitting to the stimulation unit 40.

  The secondary coil 31 and the control unit 100 are formed on the substrate 33. The receiving unit 30 is provided with a magnet (not shown) for fixing the position of the primary coil 14. The counter electrode (return electrode) 34 is connected to the control unit 100 and can be disposed at a position away from the substrate 33.

  In addition, the stimulation unit 40 is provided with a stimulation control unit 200 in which a plurality of electrodes 41 that output electrical stimulation pulse signals and a stimulation control circuit 42 are incorporated. The stimulation control unit 200 serves as a multiplexer that distributes the corresponding electrical stimulation pulse signal to each of the electrodes 41 based on the electrode designation signal sent from the control unit 100. The electrode 41 is disposed on the substrate 43, and is further electrically connected to the stimulation control circuit 42 (stimulation control unit 200) disposed on the substrate 43 by a lead wire 43a.

  The receiving unit 30 and the stimulation unit 40 are electrically connected by a plurality of wires 50 housed in a tube. In addition, although not shown in the drawings, in such an in-vivo device 20, a coating layer having high biocompatibility is formed on all components other than the tips of the electrode 41 and the counter electrode 34.

  The stimulus control unit 200 is a semiconductor integrated circuit that performs a function by a combination of semiconductor elements, and a hermetic seal (for example, a package depending on a ceramic case and a metal case) is omitted although a detailed description is omitted.

  Next, a communication circuit (power transmission circuit) 300 that transmits power and electrical stimulation pulse data and power from the extracorporeal device 10 to the intracorporeal device 20 via a coil link will be described. FIG. 3 is a circuit configuration diagram for performing power transmission between the in-vivo device and the extra-corporeal device, and FIG. 4 is a distance between the coils (distance between the primary coil 14 and the secondary coil 31) and the power transmitted by the communication circuit 300. It is a schematic diagram which shows quantity.

  The communication circuit 300 is roughly composed of a transmission circuit 301 (primary circuit) provided on the external device 10 side and a reception circuit 302 (secondary circuit) provided on the internal device 20 side. The data modulation means 13a and the battery 13b are connected to the transmission circuit 301, and the control circuit 32 and the like are connected to the reception circuit 302. The data modulation means 13a functions as a power amplifier for converting the voltage supplied from the battery 13b serving as a power source (here, a DC power source) into a constant voltage AC and amplifying the power. For convenience of explanation, the illustration of the stimulus control circuit 42 is omitted.

  First, the configuration of the transmission circuit (primary side circuit) 301 will be described. A primary coil 14, which is opposed to the secondary coil 31 and forms a coil link, a first reactance 81, a second reactance 82, a data modulation means 13a, and a power source (battery) 13b are provided. In the present embodiment, the reactance 81 is a capacitor having a capacitive reactance (capacitance), and is a variable capacitor whose capacity can be changed. The variable capacitor is used for adjustment during assembly of the device. The primary coil 14 has a self-inactance represented by L1, and the reactances 81 and 82 have reactances represented by X1a and X1b, respectively. The data modulation means 13a and the power source 13b constitute a constant voltage AC power source (power amplifier) V.

  A reactance 81 is connected in series to the primary coil 14, and a reactance 82 is connected in parallel to the constant voltage AC power supply V. In the present embodiment, the reactance 81 is not provided for the purpose of resonating with the primary coil 14, and the secondary side circuit (the maximum distance and the minimum distance between the primary coil 14 and the secondary coil 31 are preliminarily set. The power (required power) of the receiving circuit 302) is designed to be substantially the same (preferably the same). Here, the minimum distance is assumed to be, for example, about 1 mm to 5 mm assuming the minimum thickness of the wearer's skin in a situation where the primary coil 14 and the secondary coil 31 are installed without positional displacement. The maximum distance is assumed to be about 6 mm to 15 mm, for example, assuming that the wearer's skin is thick in a situation where the primary coil 14 and the secondary coil 31 are displaced to some extent.

  The reactance 82 has a role of compensating for the phase shift between the voltage and the current caused by the reactance 81 (improves the power factor). Here, when X1a (capacitance) of the reactance 81 designed is smaller than the inductance of the primary coil 14, a capacitor is used as the reactance 82. On the other hand, if the reactance 81 is capacitive and designed to be larger than the inductance of the primary coil 14 (overcompensation), the coil is used as the reactance 82. In the case where the reactance 81 is designed to be overcompensated, it is preferable that the reactance 81 is designed to be overcompensated and a coil is used for the reactance 82 because there is less power fluctuation in the secondary circuit. The reactance 82 is set so that the power peak due to the power amplifier (data modulation means 13a) when the inter-coil distance changes from the aforementioned minimum distance to the maximum distance to improve the power factor is reduced (preferably minimized). ) Designed.

  Next, the configuration of the receiving circuit (secondary side circuit) 302 will be described. The receiving circuit 302 includes a secondary coil 31, a capacitor 61, and a control circuit 32 that are disposed to face the primary coil 14. The secondary coil 31 has a self-inactance represented by L2, and the capacitor 61 is a variable capacitor and has a capacitance represented by C2. Here, the coupling coefficient of the primary coil 14 and the secondary coil 31 is k. The coupling coefficient k depends on the inter-coil distance. The shorter the inter-coil distance, the higher the numerical value. Here, the coupling coefficient k is in the range of 0.05 to 0.5, preferably about 0.15 to 0.3. The number of turns of the secondary coil 31 is set to n times the number of turns of the primary coil 14. Therefore, the turns ratio of the primary coil 14 and the secondary coil 31 is 1: n.

  A capacitor 61 is connected in parallel to the secondary coil 31, and a control circuit 32 is connected in parallel to the secondary coil 31 and the capacitor 61. A parallel resonance circuit is formed by the secondary coil 31 and the capacitor 61. In this resonance circuit, the capacitance C2 is adjusted so as to resonate with the oscillation frequency (frequency of electromagnetic waves) of the transmission circuit 301. The control circuit 32 incorporates a rectifier circuit, and has a configuration for rectifying an AC signal received by the secondary coil 31 to obtain power for driving the control circuit 32, the stimulation control circuit 42 in the subsequent stage, and the like. In this way, the receiving circuit 302 is formed. Here, the equivalent resistance of the receiving circuit 302 including the circuits after the control circuit 32 is R.

  The transmission circuit 301 and the reception circuit 302 as described above form a communication circuit 300 that transmits electric power and electrical stimulation pulse data from the primary side (external) to the secondary side (internal).

  Next, the difference between the conventional power transmission circuit and the power transmission circuit of this embodiment will be described using the relationship between the distance between the coils and the power. 4 (a) and 4 (b) show conventional examples, and FIG. 4 (c) shows an example of this embodiment. The horizontal axis represents the distance between the coils, and the vertical axis represents the power received by the receiving circuit. As a conventional example, for example, in the transmission circuit 301 described above, a circuit without the reactance 81, a circuit without the reactance 82, or a circuit in which reactance is inserted for impedance matching with the power amplifier in the primary side circuit. Etc.

  In the conventional example, on the primary side, a primary coil and a capacitor are connected in parallel to a constant pressure power source (a high frequency power source having a constant voltage amplitude), and a resonance circuit is formed by the primary coil and the capacitor. On the secondary side, a secondary coil and a capacitor are connected in parallel with the load resistance (control circuit or the like), and a resonance circuit is formed by the secondary coil and the capacitor.

  When the secondary side is perfectly tuned with the primary side, the input impedance Zi of the primary coil is expressed by the following equation (1) using the coil coupling coefficient k and the turns ratio n. Note that j is an imaginary number and ω is a frequency (angular frequency).

Zi = jωL1 (1−k ² ) + (R / n ² ) k ² (1)
From the equation (1), the input impedance Zi on the primary side changes linearly with respect to the change of the square of the coupling coefficient k.

The power consumed on the secondary side is the same as the power consumed by the equivalent resistance (resistance component of the input impedance Zi) R1 = (R / n ² ) k ² on the primary side. While it changes greatly with the change of the coupling coefficient k, the magnitude of the Zi vector does not change much since L1 is usually large. When driven by a constant voltage source, the current flowing through the primary coil hardly changes, and the power on the secondary side changes as much as R1 changes. In this case, if the secondary circuit is designed to operate even when the inter-coil distance is maximum, extra power is sent when the inter-coil distance is minimum (see FIG. 4A).

  Further, when the coil is directly driven by a power source, the power factor is low and the power loss is large. For this reason, when the compensating reactance is inserted and driven in a resonated state, the load of the high frequency power source is almost only R1, and the distance between the coils increases, and when R1 decreases, the coil current increases and the secondary side is increased. The power increases, and unnecessary power supply is performed (see FIG. 4B).

  In the present embodiment, the reactance 81 connected in series to the primary coil 14 is designed so that the secondary side power is the same in the case where the distance between the coils is minimum and the maximum without causing resonance. To do. The power factor is improved by inserting a reactance 82 in parallel with the constant voltage source V. This is schematically shown in FIG. Thus, there is little power loss compared with Drawing 4 (a) and Drawing 4 (b). In this case, the power increases between the temporarily determined minimum distance and the maximum distance, but the loss is low compared to FIGS. 4 (a) and 4 (b). Further, by compensating the reactance of the primary coil 14, the tendency of increasing the lost power is improved. Here, the fluctuation of electric power between the minimum distance and the maximum distance is reduced by lowering the peak of electric power having unimodal characteristics. Thereby, the loss of the electric power according to the distance between coils can be suppressed, and efficient electric power transmission can be performed. Further, since it is not necessary to use a detector or a control circuit for controlling the amount of power supplied according to the distance between the coils in the primary side circuit, the circuit configuration can be simplified. In addition, the reception power can be stabilized without using such a circuit.

  The intracorporeal device 20 having such a configuration is installed at a predetermined position in the patient's body. FIG. 5 is a diagram illustrating an example in which the stimulation unit 40 is installed in the patient's eye E. As shown in the drawing, a part of the substrate 43 is placed between the sclera E3 and the choroid E2 with the electrode 41 formed on the substrate 43 being in contact with the choroid E2. Further, the stimulation control unit 200 portion of the substrate 43 is placed outside the sclera E3. The placement of the substrate 43 is performed by incising a part of the sclera E3 to form a scleral pocket and inserting the electrode portion of the substrate 43 into the scleral pocket (outside the choroid E2). .

  The counter electrode 34 is placed at a position from the anterior eye portion in the center of the eye as shown in the figure, so that the retina E1 is positioned between the electrode 41 and the counter electrode 34.

  On the other hand, the secondary coil 31 is installed at a predetermined position in the living body that can receive signals (data signal for electrical stimulation pulse and power) from the primary coil 14 provided in the extracorporeal device 10. For example, the receiving unit 30 (only the secondary coil 31 is shown in the figure) is embedded under the skin of the patient's temporal region, and the primary coil 14 is placed at a position facing the receiving unit 30 through the skin (see FIG. (See FIG. 1). Since the magnet is attached to the receiving unit 30 in the same manner as the primary coil 14, the primary coil 14 and the receiving unit 30 are attracted and the primary coil 14 is held on the temporal region.

  The wire 50 extends from the receiving unit 30 embedded in the temporal region under the skin toward the patient's eye along the temporal region, and is inserted into the eye socket through the inside of the patient's upper eyelid. As shown in FIG. 4, the wire 50 placed in the eye socket passes through the outer side of the sclera E <b> 3 and is connected to the stimulation control circuit 42 installed on the substrate 43.

  In the present embodiment, the installation position of the in-vivo device 20 (stimulation unit 40) is positioned on the sclera E3 side, and the cells constituting the retina E1 are electrically stimulated from the sclera side (choroid side). However, it is not limited to this. It is only necessary that the electrode can be installed at a position where cells constituting the retina of the patient's eye can be suitably stimulated. For example, the internal device is placed in the eye of the patient's eye (on the retina or below the retina), and the tip of the substrate on which the electrode is formed is placed under the retina (between the retina and choroid) or on the retina. You can also

  In the visual reproduction assisting apparatus 1 having the above-described configuration, its operation will be described with reference to the control system block diagram shown in FIG. 6, focusing on the operation of the communication circuit 300 in FIG.

  The photographing data of the subject photographed by the photographing device 12 is sent to the data modulation means 13a. The modulation means 13a converts the electrical stimulation pulse data necessary for the patient to recognize the subject, uses the electric power supplied from the battery 13b as an alternating current carrier wave, and converts the electrical stimulation pulse data into the electric power by amplitude modulation. A drive signal is generated by superimposing. The drive signal is transmitted as an electromagnetic wave to the in-vivo device 20 side (secondary coil 31) via the primary coil 14.

  On the internal device 20 side, the electromagnetic wave sent from the external device 10 is received by the secondary coil 31, and the received electromagnetic wave is processed by the control circuit 32 as a drive signal for the internal device 20. The drive signal is rectified by the rectifier circuit of the control circuit 32, and the DC voltage is used by the control circuit 32. The control circuit 32 generates an electrical stimulation pulse signal and an electrode designation signal based on the received power and electrical stimulation pulse data, and sends them to the stimulation control unit 200. In addition, power for the stimulus control unit 200 is also sent.

  In the stimulation controller 200, the stimulation control circuit 42 receives power, an electrical stimulation pulse signal, and an electrode designation signal, and outputs an electrical stimulation pulse signal from each electrode 41 based on the electrode designation signal and the like. The cells constituting the retina are electrically stimulated by the electrical stimulation pulse signal output from each electrode 41, and the patient obtains vision (light sense).

  In a series of operations, even if the distance between the primary coil 14 and the secondary coil 31 changes due to walking of the patient or the like, power is efficiently supplied from the external device 10 to the internal device 20. . In this way, power transmission can be performed efficiently between the transmission circuit 301 and the reception circuit 302, and power transmission of the visual reproduction auxiliary device can be performed efficiently.

  In the present embodiment described above, power and operation signals are transmitted from the primary side (external device) to the secondary side (internal device), but the present invention is not limited to this. Any configuration may be used as long as at least power is transmitted between the extracorporeal device and the intracorporeal device. For example, with the latter configuration, the present invention can be applied to a visual reproduction assisting device having a configuration (referred to as an in-vivo imaging type) in which an electrode, an imaging device, a control circuit, and the like are configured as an in-vivo device. Specifically, in an in-vivo imaging type visual reproduction assist device, a configuration in which only power is supplied from the extracorporeal device and an operation signal of the intracorporeal device is transmitted to the extracorporeal device is conceivable. Further, in the present embodiment, the visual reproduction assisting device has been described as an example. However, the present invention is not limited to this and can be applied to a device using a power transmission circuit using a coil link. For example, a sensory regeneration assisting device such as a cochlear implant. In addition, the present invention can be applied to communication devices using RFID technology or the like, and charging of electrical equipment.

  In the present embodiment described above, circuit elements such as reactances are connected to both ends of the primary coil and the secondary coil. However, the present invention is not limited to this structure. An intermediate tap may be connected to any position of the coil, and a circuit element or the like may be connected as in the above-described embodiment.

It is the schematic which showed the external appearance of the visual reproduction auxiliary | assistance apparatus in embodiment of this invention. It is the schematic which showed the in-vivo apparatus of the visual reproduction assistance apparatus. It is a typical circuit block diagram of a communication circuit. It is a schematic diagram which shows the relationship between the distance between coils, and electric power. It is the figure which showed the state which installed the irritation | stimulation part in the body. It is the block diagram which showed the control system of the visual reproduction auxiliary | assistance apparatus in this embodiment.

DESCRIPTION OF SYMBOLS 1 Visual reproduction | regeneration assistance apparatus 10 External device 14 Primary coil 20 In-vivo device 30 Receiving part 31 Secondary coil 32 Control circuit 34 Counter electrode 40 Stimulus part 41 Electrode 42 Stimulation control circuit 43 Board | substrate 81,82 Reactance 100 Control part 200 Stimulation control part 300 communication circuit 301 transmission circuit 302 reception circuit

Claims (5)

In a power transmission circuit for transmitting power output from a power amplifier having a constant voltage amplitude by using a coil link of a primary side circuit having a primary coil and a secondary side circuit having a secondary coil,
The primary circuit is
The primary coil, a first reactance connected in series to the primary coil, a previous power amplifier, and a second reactance connected in parallel to the power amplifier;
The first reactance is designed such that the power of the secondary side circuit is the same with respect to a minimum distance and a maximum distance between the primary coil and the secondary coil that are set temporarily,
The second reactance is designed to reduce the power peak of the power amplifier when the distance between the coils is changed from the minimum distance to the maximum distance in order to improve the power factor of the power amplifier. Power transmission circuit. 2. The power transmission circuit according to claim 1, wherein the reactance of the first reactance is capacitive and is designed to be larger than the inductance of the primary coil. Transmission circuit. 3. The power transmission circuit according to claim 2, wherein the second reactance is a coil. 4. The power transmission circuit according to claim 1, wherein the voltage amplitude of the power amplifier is modulated during transmission from the primary side circuit to the secondary side circuit. A visual reproduction assisting device comprising the power transmission circuit according to claim 1.

Images