Capsule type medical device

In a capsule endoscope, on an inside of a capsule type housing including a cylindrical main body section and two semispherical end cover sections and having a rotationally symmetrical shape with respect to a center axis of the housing, an image pickup board section, a transmission board section, and a reception board section are housed such that principal planes of the image pickup board section, the transmission board section, and the reception board section are orthogonal to the center axis. A coil wire of at least one of a transmission coil formed by a transmission coil wire and a reception coil formed by a reception coil wire, respective principal planes of which are orthogonal to the center axis, is disposed on the end cover section side of the housing.

BACKGROUND OF INVENTION

1. Field of the Invention

Embodiments of the present invention relate to a capsule type medical device introduced into a body and, more particularly, to a capsule type medical device including a reception coil for receiving an external signal and a transmission coil for transmitting information acquired in the body to an outside as an information signal.

2. Description of the Related Art

In recent years, a capsule endoscope including an image pickup function and a radio transmission function has emerged in the market. After being swallowed by an examinee, the capsule endoscope moves on insides of digestive tracts such as a stomach and a small intestine following a peristaltic movement and picks up images of insides of organs using the image pickup function until the capsule endoscope is naturally discharged.

Images picked up by the capsule endoscope while the capsule endoscope moves in the digestive tracts are transmitted to an external device provided on an outside of a subject as an image signal by the radio transmission function and stored in a memory of the external device. After swallowing the capsule endoscope, the examinee can freely act by carrying the external device including a radio reception function and a memory function. After observation by the capsule endoscope, the images stored in the memory of the external device are displayed on a display or the like and diagnosis or the like is performed.

Japanese Patent Application Laid-Open Publication No. 2006-280940 discloses a capsule endoscope in which an antenna formed by a transmission coil for radio transmission is embedded in a wiring board. Note that the antenna is also disposed in a center of a capsule type housing.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, there is provided a capsule type medical device including: an information acquisition board section on which an information acquiring section configured to acquire in vivo information is disposeds; a transmission board section on which a transmitting section configured to transmit the in vivo information as an information signal by radio is disposed; and a reception board section on which a receiving section configured to process an inputted external signal is disposed. The information acquisition board section, the transmission board section, and the reception board section are housed on an inside of a capsule type housing, which includes a cylindrical main body section and two semispherical end cover sections and having a rotationally symmetrical shape with respect to a center axis of the housing, such that principal planes of the information acquisition board section, the transmission board section, and the reception board section are orthogonal to the center axis. A coil wire of at least one of a transmission coil formed by a transmission coil wire for transmitting the information signal and a reception coil formed by a reception coil wire for receiving the external signal, respective principal planes of which are orthogonal to the center axis, is disposed on the end cover side of the housing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

First Embodiment

As shown inFIG. 1andFIG. 2, in a capsule endoscope (hereinafter referred to as “endoscope”)10, which is a capsule type medical device in the present embodiment, a circuit board20including a plurality of substantially circular board sections is housed and sealed on an inside of a capsule type housing11in a bent state.

The endoscope10is a device introduced into a subject that, after being swallowed by an examinee, photographs images in a body at a predetermined time interval. The endoscope10is capable of not only transmitting image data acquired in the body to an outside by radio but also receiving a signal from the outside and performing control based on the signal.

The housing11includes a cylindrical main body section12and substantially semispherical end cover sections13A and13B at both ends of the main body section12. The end cover section13A is made of a transparent material. The main body section12and the end cover section13B are made of an opaque material. However, the main body section12and the end cover section13B may be integrally molded. The elongated housing11has a rotationally symmetrical shape having a center axis O in a longitudinal direction as an axis of rotational symmetry. Length L of the main body section12in a direction of the center axis O is 10 to 30 mm A diameter D in an orthogonal direction of the center axis O is 5 to 15 mm.

The circuit board20is a flexible wiring board on which a lighting board section21, an image pickup board section22, a transmission board section23, and a reception board section24, which respectively have substantially circular shapes, are coupled by connecting sections27A,27B, and27C, which respectively have substantially rectangular shapes. The flat circuit board20is housed on an inside of the housing11such that the connecting sections27are bent 180 degrees together with spacer members (not shown in the figures) for determining an arrangement of the respective board sections and respective principal planes of the circuit board20are orthogonal to the center axis.

Note that a battery and a magnet not shown in the figures are also housed on the inside of the housing11. The battery is a power supply source. The magnet is arranged in order to control an image pickup direction of the endoscope10using an external magnetic field. When a direct-current magnetic field is applied to the magnet from an outside, the magnet changes a posture of the housing11such that a magnetization direction becomes parallel to a line of magnetic force from the outside.

On a front surface21U of the lighting board section21, a plurality of light emitting elements, for example, four LEDs (21A) are respectively mounted on LED mounting lands21AB, which are made of metal such as copper, around a substantially circular opening21H. In the following explanation, a front surface of the circuit board20refers to a surface on which the LEDs (21A) are disposed.

As explained in detail below, a transmission coil40is disposed on a rear surface21D of the lighting board section21. A reception coil50is disposed on a front surface24U of the reception board section24.

On the image pickup board section22, which is an information acquisition board section, an image pickup chip22A, which is an image pickup section, is disposed with an image pickup surface directed to the opening21H. A lens unit22B is arranged on the image pickup surface of the image pickup chip22A. The image pickup chip22A is an information acquiring section configured to acquire an endoscopic image, which is in vivo information. On the transmission board section23, a transmitting section23A configured to transmit image data acquired by the image pickup chip22A as an image signal (an information signal) by radio via the transmission coil40is disposed. On the reception board section24, a receiving section24A configured to receive an external signal via the reception coil50and process the external signal is disposed. For example, the external signal is an alternating magnetic field signal. The endoscope10drives a frequency dividing circuit with a pulse signal obtained by rectifying the received external signal and controls ON and OFF of power supply to internal circuits of the image pickup chip22A, the LEDs (21A), the transmitting section23A, and the like. A plurality of wires (not shown in the figures) for electrically connecting the respective board sections are formed in the connecting sections27A to27C.

As shown inFIG. 3AtoFIG. 3C, the transmission coil40disposed on the rear surface21D of the lighting board section21is a spiral plane coil formed by a spiral transmission coil wire41and having a principal plane orthogonal to the center axis O. Like the transmission coil40, the reception coil50disposed on the front surface24U of the reception board section24is a spiral plane coil formed by a spiral reception coil wire (not shown in the figures) and having a principal plane orthogonal to the center axis O. Note that the principal plane of the plane coil means a principal plane of a base on which the coil wire is formed.

The transmission coil wire41and the reception coil wire made of a conductive material such as copper are manufactured simultaneously with manufacturing of connection lands for electronic component mounting, for example, the LED mounting lands21AB. That is, the transmission coil wire41and the like are manufactured using a normal formation method (an additive method, a subtractive method, etc.) in which photolithography is used. Note that the coil wires may be manufactured by winding a coated conductive wire on a plane. Manufacturing methods, the sizes, the numbers of turns, and the like of the transmission coil40and the reception coil50, which have different transmission and reception frequencies, may be different.

In the endoscope10, the transmission coil40and the reception coil50are disposed on the end covers13A and13B sides of the housing11. That is, as shown inFIG. 1, the transmission coil40is disposed in a position at a distance ΔL1 from one end of the main body section12and the reception coil50is disposed in a position at a distance ΔL2 from the other end of the main body section12. ΔL1 and ΔL2 are equal to or smaller than 20% of L and preferably equal to or smaller than 10% of L.

The battery, the magnet, the electronic components mounted on the circuit board20, and the like are electromagnetism shields and adversely affect transmission and reception of a radio signal. However, the transmission coil40and the reception coil50disposed on end sides of the main body section12where ΔL1 and ΔL2 are equal to or smaller than the range are less easily affected by the mounted components and the like. Further, a distance L1 between the transmission coil40and the reception coil50is equal to or larger than (L−ΔL1−ΔL2)=(0.80×L) and preferably equal to or larger than (0.90×L).

Note that the transmission coil40or the reception coil50may be disposed on an inside of the end cover section13A or13B. That is, the end covers13A and13B sides of the housing11include main body section sides of the end cover sections13A and13B in addition to end sides of the main body section12. When the transmission coil40or the reception coil50is disposed on the inside of the end cover section13A or13B, L<L1. In the distance L1, a sign of ΔL1 and ΔL2 can be regarded as minus.

In the capsule endoscope including the transmission coil and the reception coil, when the transmission coil and the reception coil interfere with each other, it is likely that transmission and reception efficiency is deteriorated. However, even if the endoscope10is a capsule endoscope having small length L, it is possible to minimize an influence of mutual interference of the transmission coil40and the reception coil50.

Therefore, transmission and reception of the endoscope10is efficient.

Note that a frequency of the image signal and a frequency of the external signal are different. When influences by harmonics and subharmonics are taken into account as well, it is particularly preferable that the frequency of the image signal and the frequency of the external signal not be an integral multiple or fraction having one as the numerator over an integer of each other.

In the endoscope10, in order to obtain a maximum effect, the transmission coil40and the reception coil50are disposed at both the ends of the main body section12. However, if the coil wire of one of the transmission coil40and the reception coil50is disposed on the lighting board section21at the end, it is possible to obtain a predetermined effect. In this case, the distance L1 between the transmission coil40and the reception coil50is preferably equal to or larger than (0.50×L).

An alternating magnetic field may be received and rectified by the reception coil50to obtain electric power of the endoscope10. An endoscope that uses received power as driving power does not need to incorporate a battery. Since there is no limitation on a driving time due to a battery capacity, an in vivo observation for a long time is possible. In an endoscope incorporating a secondary battery, when a battery capacity decreases, it is possible to charge the secondary battery by receiving an external magnetic field signal.

Note that the LEDs (21A) mounted on the lighting board section21are elements that generate heat. The transmission coil wire41manufactured on the lighting board section21is made of a metal material having high conductivity such as copper. Therefore, the transmission coil wire41has not only a transmission and reception function but also a heat radiation function. Even if the LEDs (21A) generate heat, an operation of the endoscope10is stable because heat radiation is accelerated via the transmission coil wire41.

Modifications of the First Embodiment

Next, modifications of the first embodiment are explained. Endoscopes in the modifications are similar to the endoscope10in the first embodiment. Therefore, the same components are denoted by the same reference numerals and signs and explanation of the components is omitted.

As shown inFIG. 4AtoFIG. 4C, in an endoscope in a modification 1, a coil wire42of the transmission coil40is disposed in an outer circumferential region of the four LEDs (21A) disposed on the front surface21U of a lighting board section21A.

As shown inFIG. 5AtoFIG. 5C, in an endoscope in a modification 2, the transmission coil40includes the transmission coil wire41disposed on the rear surface21D of a lighting board section21B and a transmission coil wire42disposed on the front surface21U. The transmission coil wire41and the transmission coil wire42are connected by a through board wire. Note that the transmission coil wire41and the transmission coil wire42shown inFIG. 5AtoFIG. 5Chave substantially the same shapes. However, the transmission coil wire41may be wound to a further inner circumferential section. A transmission coil including coil wires on both surfaces of a board section has a large number of times of winding (number of turns). Therefore, transmission and reception efficiency of the transmission coil is high.

Note that a disposing position of the transmission coil40including a plurality of plane coils is regarded as a center of positions of a plurality of plane coil wires, for example, a center in a thickness direction of the lighting board section21B.

As shown inFIG. 6, the transmission coil40of an endoscope in a modification 3 includes an insulating layer45configured to cover the transmission coil wire41disposed on the rear surface21D of a lighting board section21C. The insulating layer45manufactured using an insulative resin solution or an insulative sheet contributes to improvement of reliability of the transmission coil wire41.

As shown inFIG. 7, in an endoscope in a modification 4, in a lighting board section21E, a coil board section46, in a center of which the transmission coil wire41including a substantially circular opening having the same size as the opening21H is disposed, is bonded to the rear surface21D of a lighting board section21P via, for example, an adhesive and integrated.

The coil board section46can be manufactured separately from the circuit board20. Therefore, the manufacturing of the coil board section46is easy. In order to further increase the number of turns, coil wires may be manufactured on both surfaces of the coil board section46. The coil board section46including a coil wire on one surface or including coil wires on both surfaces may be joined to the lighting board section21P including a coil wire on one surface or including coil wires on both surfaces.

Note that it is preferable that the transmission coil wire41on the rear surface21D of the lighting board section21P is not disposed right under the LED mounting lands21AB disposed on the front surface21U. This is because it is likely that the LED mounting lands21AB made of metal interfere with the transmission coil wire41. However, the above does not apply, in particular, in a small-diameter capsule endoscope.

Note that the transmission coil40in the modifications is explained. However, the same configuration can be used in the reception coil50as well. For example, a reception coil wire may be formed on a rear surface of the reception board section24. Reception coil wires may be formed on both surfaces of the reception board section24. A reception coil board may be joined to the rear surface of the reception board section24.

A plurality of board sections may be an integral board section. For example, the transmission board section23and the reception board section24may be an integral transmission and reception board section.

Second Embodiment

An endoscope10A in a second embodiment is explained. The endoscope10A is similar to the endoscope10in the first embodiment. Therefore, the same components are denoted by the same reference numerals and signs and explanation of the components is omitted.

As shown inFIG. 8, the endoscope10A is a so-called binocular type including two image pickup chips22A and25A configured to photograph visual fields in opposite directions to each other.

As shown inFIG. 8, a circuit board20A of the endoscope10A is configured by arranging, in a row, the first lighting board section21, the first image pickup board section22, the transmission board section23, the reception board section24, a second image pickup board section25, and a second lighting board section26in order via connecting sections thereof.

The first lighting board section21and the second lighting board section26have substantially the same configurations. The first image pickup board section22and the second image pickup board section25also have substantially the same configurations.

The two image pickup chips22A and25A of the endoscope10A of the binocular type are disposed such that image pickup directions thereof are opposite directions along the center axis O of the housing11.

In the endoscope10A, the transmission coil40is disposed on the first lighting board section21arranged at an end of the main body section12. The reception coil50is disposed on the second lighting board section26arranged at the other end.

The endoscope10A in the present embodiment has an effect same as the effect of the endoscope10and is the binocular type.

Note that, in the endoscope10A, the explained configurations of the modification of the endoscope10can be used. The first lighting board section21and the second lighting board section26may be configured differently.

In the above explanation, the capsule endoscope is explained as an example. However, the same effect is provided with various capsule type medical devices such as a capsule type medical device for digestive fluid sampling, a pH sensor of a swallow type, and a drug delivery system.

The present invention is not limited to the embodiments explained above and various alterations, modifications, and the like are possible in a range in which the gist of the present invention is not changed.