WO2014208630A1

WO2014208630A1 - Capsule medical system, position detection device and capsule medical device

Info

Publication number: WO2014208630A1
Application number: PCT/JP2014/066908
Authority: WO
Inventors: 千葉　淳; 拓人井開; 瀧澤　寛伸; 木村　敦志; 隆広飯田; 佐藤　良次
Original assignee: オリンパスメディカルシステムズ株式会社
Priority date: 2013-06-27
Filing date: 2014-06-25
Publication date: 2014-12-31
Also published as: JP5792403B2; JPWO2014208630A1

Abstract

Provided are a capsule medical system, etc. which are capable of reducing power consumption of a battery built in a capsule medical device and of stably and accurately detecting a position of the capsule medical device. A capsule endoscope (10) comprises a power supply unit (140) which includes a battery, a magnetic field generating unit (150) which is powered by the power supply unit (140) to generate a magnetic field, a control unit (120) which controls the power supply from the power supply unit (140) to the magnetic field generating unit (150), and an imaging unit (110) which is powered by the power supply unit (140) to obtain information relating to the subject, wherein the control unit (120) performs control such that power is supplied intermittently from the power supply unit (140) to the magnetic field generating unit (150) in synchronization with operation of the imaging unit (110).

Description

Capsule type medical system, position detection device, and capsule type medical device

The present invention relates to a capsule medical system using a capsule medical device that is introduced into a subject and acquires information in the subject, a position detection device that detects the position of the capsule medical device, and a capsule medical device About.

In recent years, development of capsule-type medical devices that are sized to be introduced into the digestive tract of a subject such as a patient has been underway. In the field of endoscopes, capsule endoscopes that have an imaging function and a wireless communication function inside a capsule-shaped casing have been put into practical use. After being swallowed by a subject, the capsule endoscope captures the inside of the subject while moving in the digestive tract, generates image data, and wirelessly transmits the image data to a receiving device provided outside the subject (for example, Patent Document 1). The image data received by the receiving device is then taken into an image processing device such as a workstation and subjected to predetermined image processing. Thereby, in the image processing apparatus, an image in the subject (hereinafter also referred to as an in-vivo image) can be reproduced and displayed as a still image or a moving image.

Since the capsule medical device normally moves in the digestive tract by the peristaltic movement of the subject, the position in the subject cannot be controlled. For this reason, in order to specify the position of the part shown in the in-vivo image, a system for detecting the position and posture of the capsule medical device in the subject has been developed. For example, Patent Document 2 discloses a technique for detecting the position of a capsule by providing a coil in a capsule and detecting a magnetic field generated by supplying electric power to the coil from a battery outside the subject. Yes.

JP 2006-75536 A JP 2005-535376 Gazette

By the way, the capsule medical device is operated by a battery built in the housing. The power supplied from the battery is consumed for main operations such as illumination and imaging, and wireless transmission of generated image data, in addition to generating a magnetic field in the above-described coil. For this reason, the main operation such as illumination causes the power supply voltage to drop temporarily, the magnetic field for position detection becomes unstable, and the position detection accuracy of the capsule medical device is affected.

Also, the capsule medical device having the function of generating a magnetic field for position detection has a problem that the power consumption is increased and the operation time is shortened as compared with a capsule medical device not having the function. In order to extend the operation time of the capsule medical device, for example, it is conceivable to suppress the magnitude of the current supplied to the coil. However, in this case, the strength of the generated magnetic field becomes weak, and there is a possibility that the position detection accuracy of the capsule medical device is lowered.

The present invention has been made in view of the above, and is capable of stably and accurately detecting the position of a capsule medical device while suppressing power consumption of a battery built in the capsule medical device. An object is to provide a medical system, a position detection device, and a capsule medical device.

In order to solve the above-described problems and achieve the object, a capsule medical device according to the present invention is used by being introduced into a subject and generates a magnetic field for position detection, and the magnetic field. A capsule medical device used in a capsule medical system including a position detection device that detects a position of the capsule medical device based on the battery, and generates a magnetic field by receiving power from the battery and the battery A magnetic field generation means; a control means for controlling power supply from the battery to the magnetic field generation means; and an information acquisition means for receiving information about the inside of the subject by receiving power supply from the battery, The control means performs control so that power is intermittently supplied from the battery to the magnetic field generation means in synchronization with the operation of the information acquisition means.

The capsule medical device further includes voltage detection means for detecting a voltage value of the battery, and the control means is based on a detection result by the voltage detection means, during the period in which the voltage value is less than a predetermined threshold. The power supply from the battery to the magnetic field generating means is stopped.

In the capsule medical device, the control unit stops power supply from the battery to the magnetic field generation unit during an operation period of the information acquisition unit.

In the capsule medical device, the control unit stops power supply from the battery to the magnetic field generation unit during an operation period of the information acquisition unit and at least one predetermined time before and after the operation period. It is characterized by making it.

In the capsule medical device, the control unit detects an operation start timing of the information acquisition unit, and stops power supply from the battery to the magnetic field generation unit for a predetermined period from the operation start timing. To do.

A capsule-type medical system according to the present invention is a capsule-type medical device that is introduced into a subject and used, and includes a battery, a magnetic field generating unit that generates a magnetic field by receiving power supplied from the battery, A capsule medical device having control means for controlling power supply from a battery to the magnetic field generating means, and a position detecting device for detecting a position of the capsule medical device, wherein the magnetic field generated by the magnetic field generating means And a processing means for executing a process for calculating the position of the capsule medical device based on the detection signal output from the magnetic field detection means. And the control means controls the power supply to be intermittently supplied from the battery to the magnetic field generation means.

In the capsule medical system, the processing unit performs the processing using a detection signal having an intensity equal to or higher than a predetermined value among detection signals output from the magnetic field detection unit.

In the capsule medical system, when the control unit starts power supply from the battery to the magnetic field generation unit, the control unit executes power supply in a specific pattern indicating the start, and the processing unit performs the magnetic field generation. The processing is started when the detecting means detects a magnetic field that changes in the pattern.

In the capsule medical system, the processing unit detects at least one of a rising timing and a falling timing of the detection signal and starts the processing.

In the capsule medical system, the processing unit performs the process using the detection signal output from the magnetic field detection unit within a predetermined period after detecting the rising timing of the detection signal. .

In the capsule medical system, the position detection device further includes a storage unit that stores a detection signal output from the magnetic field detection unit, and the processing unit detects a falling timing of the detection signal, A detection signal in a period preceding the falling timing by a predetermined period is acquired retrospectively from the storage unit, and the processing is executed using the acquired detection signal.

In the capsule medical system, the processing unit performs the processing by replacing a signal value of a detection signal whose intensity is smaller than a predetermined value among detection signals output from the magnetic field detection unit with zero. Features.

In the capsule medical system, the processing unit performs the processing for a predetermined period at a predetermined cycle, and the length of one period in which power is supplied from the battery to the magnetic field generation unit is the processing unit. Is longer than the period in which the process is executed twice.

In the capsule medical system, the processing includes fast Fourier transform processing on the detection signal, the processing means performs the processing for a predetermined period at a predetermined cycle, and power is supplied from the battery to the magnetic field generating means. The length of one supplied period is equal to or longer than a period in which the processing means executes the fast Fourier transform process twice.

In the capsule medical system, the capsule medical device includes a casing having a cylindrical body and at least one dome provided at an end of the body, and at least the inside from the casing. Imaging means for imaging the outside of the housing through one dome, and the magnetic field generating means includes a coil that generates a magnetic field when a current flows, and a driving means that drives the coil. And the coil is wound around a position that is centered on an axis inclined with respect to the central axis of the housing, has a diameter larger than the diameter of the body portion, and does not interfere with the field of view of the imaging unit. Or a portion that is wound around the outer periphery of the housing and is parallel to the central axis of the body portion, and a portion that extends along the circumferential direction of the body portion.

According to the present invention, since the magnetic field is intermittently generated from the capsule medical device in synchronism with the operation of the information acquisition means, the position of the capsule medical device can be detected stably and accurately. According to the present invention, since the magnetic field is generated intermittently by intermittently supplying power from the battery to the magnetic field generating means in the capsule medical device, the position detection accuracy of the capsule medical device is lowered. In addition, the power consumption of the battery built in the capsule medical device can be suppressed.

FIG. 1 is a schematic diagram showing a configuration example of a capsule medical system according to Embodiment 1 of the present invention. FIG. 2 is a schematic diagram showing the configuration of the capsule endoscope shown in FIG. FIG. 3 is a circuit diagram showing a configuration of the magnetic field generator shown in FIG. FIG. 4 is a flowchart showing the operation of the capsule medical system shown in FIG. FIG. 5 is a diagram showing a current level corresponding to the driving cycle of the transmission coil shown in FIG. FIG. 6 is a diagram showing a current level when the transmission coil is always driven. FIG. 7 is a diagram for explaining the timing of capturing the detection signal output from the magnetic field detection unit shown in FIG. 1 into the signal processing unit. FIG. 8 is a diagram for explaining the timing of capturing the detection signal output from the magnetic field detection unit shown in FIG. 1 into the signal processing unit. FIG. 9 is a diagram for explaining the timing of capturing the detection signal output from the magnetic field detection unit shown in FIG. 1 into the signal processing unit. FIG. 10 is a diagram for explaining the FFT window filter processing. FIG. 11A is a graph showing the characteristics of the Hamming window, and FIG. 11B is a graph showing the frequency spectrum extracted by the FFT process. FIG. 12 is a diagram illustrating the relationship between the drive timing of the transmission coil and the imaging and transmission timing. FIG. 13 is a diagram illustrating the delay time when the generation period of the alternating magnetic field is different from the magnetic field detection period. FIG. 14 is a block diagram illustrating a configuration of a signal processing unit included in the position detection device according to the second embodiment. FIG. 15 is a diagram for explaining the operation of the intermittent timing detection unit shown in FIG. 14 (when synchronized with the rising of the alternating magnetic field). FIG. 16 is a diagram for explaining the operation of the intermittent timing detector shown in FIG. 14 (when synchronized with the fall of the alternating magnetic field). FIG. 17 is a diagram for explaining a modification 2-1 of the operation of the intermittent timing detection unit shown in FIG. FIG. 18 is a diagram for explaining a modification 2-1 of the operation of the intermittent timing detection unit shown in FIG. FIG. 19 is a schematic diagram showing a configuration of a capsule endoscope used in Control Example 1 of power supply to a magnetic field generation unit according to Embodiment 3 of the present invention. FIG. 20 is a diagram for explaining a control example 1 of power supply to the magnetic field generation unit according to the third embodiment of the present invention. FIG. 21 is a diagram for explaining a control example 2 of power supply to the magnetic field generation unit in the third embodiment of the present invention. FIG. 22 is a diagram for explaining a third control example of power supply to the magnetic field generation unit according to the third embodiment of the present invention. FIG. 23 is a diagram for explaining a control example 4 of power supply to the magnetic field generation unit according to the third embodiment of the present invention. FIG. 24 is a diagram for explaining a control example 5 of power supply to the magnetic field generation unit according to the third embodiment of the present invention. FIG. 25 is a side view showing a first arrangement example of transmission coils. FIG. 26 is a side view showing a second arrangement example of the transmission coils. FIG. 27 is a side view showing a third arrangement example of the transmission coils. FIG. 28 is a side view showing a fourth arrangement example of the transmission coils. FIG. 29 is a diagram illustrating a fifth arrangement example of the transmission coils. FIG. 30 is a diagram illustrating a sixth arrangement example of the transmission coils.

Hereinafter, a capsule medical device, a position detection device, and a capsule medical system according to an embodiment of the present invention will be described with reference to the drawings. In the following description, a capsule endoscope that is orally introduced into a subject and images the inside of the subject (intraluminal) is illustrated as an embodiment of the capsule medical device. The present invention is not limited by the form. That is, the present invention measures, for example, a capsule endoscope that moves in the lumen from the esophagus to the anus of the subject, a capsule medical device that delivers a drug or the like into the subject, and a PH in the subject. The present invention can be applied to various medical devices having a capsule shape, such as a capsule medical device including a PH sensor.

In the following description, each drawing merely schematically shows the shape, size, and positional relationship to the extent that the contents of the present invention can be understood. Therefore, the present invention is not limited only to the shape, size, and positional relationship illustrated in each drawing. In the description of the drawings, the same portions are denoted by the same reference numerals.

(Embodiment 1)
FIG. 1 is a schematic diagram showing a configuration example of a capsule medical system according to Embodiment 1 of the present invention. As shown in FIG. 1, the capsule medical system 1 according to the first embodiment wirelessly transmits an imaging signal acquired by imaging the subject as a capsule medical device introduced into the lumen of the subject 2. A capsule endoscope 10 for transmission and a position detection device 20 for detecting the position of the capsule endoscope 10 in the subject 2 are provided.

FIG. 2 is a schematic diagram showing an example of the internal structure of the capsule endoscope 10 shown in FIG. As shown in FIG. 2, the capsule endoscope 10 includes a capsule-shaped casing 101 formed in a size that can be easily introduced into the lumen of the subject 2, and is housed in the casing 101. The imaging unit 110 that captures an image of the inside of the subject 2 to acquire an imaging signal and the operation of each part of the capsule endoscope 10 including the imaging unit 110 are controlled, and the imaging signal acquired by the imaging unit 110 is controlled. A control unit 120 that performs predetermined signal processing, a transmission unit 130 that wirelessly transmits an imaging signal subjected to signal processing, a power supply unit 140 that supplies power to each unit of the capsule endoscope 10, and a capsule endoscope And a magnetic field generator 150 that generates an alternating magnetic field for detecting the position of the mirror 10. In FIG. 2, a cross section of the housing 101 is shown.

The housing 101 is composed of an exterior case having a cylindrical body portion 102 and

dome portions

103 and 104 provided at both ends of the body portion 102, respectively. The trunk | drum 102 is formed of the colored member substantially opaque with respect to visible light. At least one of the dome parts 103 and 104 (the dome part 103 on the imaging unit 110 side in FIG. 2) is formed of an optical member that is transparent to light of a predetermined wavelength band such as visible light. In FIG. 2, only one imaging unit 110 is provided in the capsule endoscope 10, but two imaging units 110 may be provided. In this case, the other dome 104 is also a transparent optical member. Formed by. Such a casing 101 includes the imaging unit 110, the control unit 120, the transmission unit 130, the power supply unit 140, and the magnetic field generation unit 150 in a liquid-tight manner.

The imaging unit 110 is information acquisition means for acquiring an imaging signal as information relating to the subject 2, and includes an illumination unit 111 including a light emitting element such as an LED and a drive circuit (not shown) for driving the light emitting element, An optical system 112 such as a lens, and an image pickup unit 113 including an image pickup device such as a CMOS image sensor or a CCD and a drive circuit (not shown) for driving the image pickup device. The illumination unit 111 irradiates the imaging field of the imaging unit 113 with illumination light such as white light, and illuminates the subject 2 in the imaging field v through the dome unit 103. The optical system 112 is arranged so that the optical axis La coincides with the long axis of the housing 101, collects the reflected light from the subject 2 in the imaging field of view v, and forms an image on the imaging surface of the imaging unit 113. . The imaging unit 113 generates an imaging signal by performing photoelectric conversion processing on an optical signal representing the image of the subject 2 formed on the imaging surface.

When two imaging units 110 are provided, the imaging units 110 are arranged at the dome at both ends of the casing 101 so that both optical axes of the two optical systems are aligned with the long axis of the casing 101. It arrange | positions at the part 103 side and the dome part 104 side, respectively. Further, when only one image pickup unit 110 is provided, the end of the housing 101 on the side where the image pickup unit 110 is not necessarily required to have a dome shape. In this case, instead of the dome 104, the end of the body 102 may be sealed with a disk-shaped member, for example.

The control unit 120 operates the imaging unit 113 at a predetermined cycle (imaging frame rate) and causes the illumination unit 111 to emit light in synchronization with the imaging frame rate. Further, the control unit 120 generates image data by performing A / D conversion and other predetermined signal processing on the imaging signal generated by the imaging unit 110. Further, the control unit 120 intermittently generates an alternating magnetic field from the magnetic field generation unit 150 by intermittently supplying power from the power supply unit 140 to the magnetic field generation unit 150. The generation pattern of the alternating magnetic field will be described later.

The transmission unit 130 includes a transmission antenna (not shown), acquires image data and related information subjected to signal processing by the control unit 120, performs modulation processing, and sequentially wirelessly transmits to the outside via the transmission antenna.

The power supply unit 140 is realized by, for example, a button-type battery and a switch unit such as a magnetic switch. The power supply unit 140 switches its on / off state when the magnetic switch is switched by a magnetic field applied from the outside, and supplies power to each unit of the capsule endoscope 10 during the on state. In addition, the power supply unit 140 stops supplying power to each unit of the capsule endoscope 10 during the off state.

The magnetic field generation unit 150 includes a transmission coil 15a that generates a magnetic field when a current flows, and a capacitor 15b that forms a resonance circuit 151 together with the transmission coil 15a, and generates an alternating magnetic field having a predetermined frequency. The arrangement of the transmission coil 15a is not particularly limited as long as the field of view of the imaging unit 113 is not hindered. In the first embodiment, the central axis of the transmission coil 15 a is arranged in parallel with the long axis of the housing 101, and the transmission coil 15 a is wound along the inner periphery of the body portion 102.

As a form of the transmission coil 15a, it is preferable that the effective area of the transmission coil 15a be as large as possible. In order to prevent the drive efficiency of the transmission coil 15a from being lowered, it is preferable not to arrange the power supply unit (battery) 140 and the transmission unit (transmission antenna) 130 in the internal space of the transmission coil 15a. For example, when two image pickup units 110 are provided at both ends of the long axis of the housing 101, the transmission coil 15 a may be disposed between these image pickup units 110.

FIG. 3 is a diagram showing the configuration of the magnetic field generator 150 in more detail. As shown in FIG. 3, the magnetic field generation unit 150 includes a signal generation unit 152 and a drive unit 153 in addition to the resonance circuit 151 including the transmission coil 15 a and the capacitor 15 b. Hereinafter, the resonance frequency of the resonance circuit 151 (that is, the frequency of the alternating magnetic field) is F ₀ .

The signal generator 152 is an oscillator including a vibrator that oscillates at a frequency corresponding to an applied voltage. A voltage that oscillates at a frequency substantially equal to an integral multiple of the resonance frequency F ₀ is applied to the vibrator.

The driving unit 153 generates an alternating magnetic field from the coil 15a by driving the coil 15a by applying a voltage to the coil 15a based on the signal generated from the signal generating unit 152.

Referring again to FIG. 1, the position detection device 20 includes a magnetic field detection unit 21 that detects an alternating magnetic field generated from the capsule endoscope 10, and the subject 2 based on the alternating magnetic field detected by the magnetic field detection unit 21. And a position detection device main body 22 for detecting the position of the capsule endoscope 10 inside.

The magnetic field detector 21 has a plurality of receiving coils 21a each receiving an alternating magnetic field and outputting a detection signal. These receiving coils 21a are arranged in a predetermined arrangement in the vicinity of the subject 2 under examination. In FIG. 1, the receiving coil 21a is disposed below the mounting table 30 on which the subject 2 lies.

The position detection device main body 22 includes an input unit 23 used to input various information and commands to the position detection device main body 22, and an output unit 24 that displays various information processed by the position detection device main body 22. The receiving unit 25 that receives the imaging signal wirelessly transmitted from the capsule endoscope 10 via the antenna 25a and the detection signal output from each receiving coil 21a are subjected to various signal processing to obtain magnetic field information. Controls the operation of each part of the signal processing unit 26, the storage unit 27, and the position detection device main body 22 to be generated, and controls the imaging signal input from the reception unit 25 and the magnetic field information input from the signal processing unit 26. And a control unit 28 for executing predetermined arithmetic processing.

The input unit 23 is realized by input devices such as various buttons, switches, and keyboards, pointing devices such as a mouse and a touch panel, and inputs various information to the control unit 28 in accordance with an input operation by the user.

The output unit 24 includes various displays such as liquid crystal and organic EL, and various information input from the input unit 23, in-vivo images of the subject 2, and position information of the capsule endoscope 10 at the time of capturing the in-vivo images. Etc. are displayed on the screen.

A plurality of antennas 25 a for receiving imaging signals wirelessly transmitted from the capsule endoscope 10 are attached to the body surface of the subject 2. The receiving unit 25 selects the antenna 25a having the highest reception intensity with respect to the imaging signal among these antennas 25a, and performs demodulation processing or the like on the imaging signal received via the selected antenna 25a. Image data corresponding to the in-vivo image of the subject 2 is acquired.

The signal processing unit 26 includes a filter unit 261 that shapes the waveform of the detection signal output from the magnetic field detection unit 21, an amplifier 262, and A / D conversion that generates detection data by performing A / D conversion processing on the detection signal. Part 263.

The storage unit 27 is realized by using a storage medium and a reading device that store information in a rewritable manner such as a flash memory or a hard disk. The storage unit 27 includes various programs and various parameters for the control unit 28 to control each unit of the position detection device main body 22, in-vivo image data of the subject 2 captured by the capsule endoscope 10, and the subject 2. The position information of the capsule endoscope 10 in the inside is stored.

The control unit 28 is configured using, for example, a CPU (Central Processing Unit) or the like, reads a program from the storage unit 27, performs instructions to each unit constituting the position detection device main body 22, transfers data, and the like, and performs the position detection device main body. The operation of 22 is comprehensively controlled. In addition, the control unit 28 includes an image processing unit 281 that performs predetermined image processing such as white balance processing, demosaicing, gamma conversion, smoothing (noise removal, etc.) on the image data input from the receiving unit 25. A position information generating unit 282 that acquires information (position information) indicating the position of the capsule endoscope 10.

The position information generation unit 282 performs fast Fourier transform processing (hereinafter referred to as FFT processing) on the detection data output from the A / D conversion unit 263 to extract magnetic field information such as the amplitude and phase of the alternating magnetic field. The processing unit 282a and a position calculation unit 282b that calculates the position of the capsule endoscope 10 based on the magnetic field information extracted by the FFT processing unit 282a.

Among these units, a processing unit that executes processing for calculating the position of the capsule endoscope 10 based on the detection signal output from the magnetic field detection unit 21 by the signal processing unit 26 and the position information generation unit 282. Constitute.

Next, the operation of the capsule medical system 1 will be described. FIG. 4 is a flowchart showing the operation of the capsule medical system 1.
First, in step S1, the power supply unit 140 of the capsule endoscope 10 is turned on and introduced into the subject 2.

In subsequent step S <b> 2, the capsule endoscope 10 intermittently supplies power from the power supply unit 140 to the magnetic field generation unit 150 and intermittently generates an alternating magnetic field from the magnetic field generation unit 150. FIG. 5 is a diagram illustrating a current level according to the driving cycle of the transmission coil 15a. As shown in FIG. 5, in the first embodiment, the current of the current value I _C is transmitted to the transmission coil 15a with a period T ₀ (= τ ₁ + τ ₂ ) and a predetermined duty ratio (τ ₁ / T ₀ ). Shed. Hereinafter, the period T ₀ is defined as a driving period of the transmission coil 15a, that is, an alternating magnetic field generation period. The period τ ₁ is an alternating magnetic field generation period (transmission coil 15a drive period), and the period τ ₂ is an alternating magnetic field off period (transmission coil 15a drive stop period).

Here, the position detection accuracy of the capsule endoscope 10 depends on the accuracy with which the magnetic field detection unit 21 detects the alternating magnetic field generated from the capsule endoscope 10, that is, the S / N ratio of the detection signal. For example, when the S / N ratio of the detection signal is improved by 6 dB, the position detection accuracy of the capsule endoscope 10 is improved twice. The S / N ratio of the detection signal is determined based on the noise of the alternating magnetic field generated by the transmission coil 15a of the capsule endoscope 10 and the detection circuit (the magnetic field detection unit 21 and the detection circuit on the position detection device 20 side that detects the alternating magnetic field). It depends on the larger of the noise in the signal processor 26).

Also, the strength of the alternating magnetic field generated by the transmission coil 15a is proportional to the current flowing through the transmission coil 15a according to the Bio-Savart law. On the other hand, since the power consumption in the magnetic field generation unit 150 is generally proportional to the current flowing through the transmission coil 15a, it is also proportional to the strength of the alternating magnetic field generated by the magnetic field generation unit 150. Therefore, if the strength of the alternating magnetic field generated by the magnetic field generation unit 150 is suppressed, the noise strength of the alternating magnetic field is expected to be reduced accordingly. In this case, the influence of noise on the position detection device 20 side is greater than the noise of the alternating magnetic field itself with respect to the S / N ratio of the detection signal.

Therefore, in the first embodiment, the power supplied from the power supply unit 140 to the magnetic field generation unit 150 is intermittently supplied to the magnetic field generation unit 150 instead of weakening the intensity of the current flowing through the transmission coil 15a ( By providing the drive off period), power consumption in the magnetic field generator 150 is suppressed. On the other hand, as described later, the position detection device 20 does not use the detection signal corresponding to the drive-off period for the position calculation of the capsule endoscope 10.

In order to provide a period during which the driving of the transmission coil 15a is turned off, for example, power supply from the power supply unit 140 to the magnetic field generation unit 150 may be repeatedly turned on / off at a fixed period and a fixed duty ratio. In this case, during the drive-on period, the current value that flows through the transmission coil 15a may be increased by the duty ratio. Further, the driving cycle T ₀ and the duty ratio may not be constant. In order to enable the magnetic field detection unit 21 to detect the drive-off period of the transmission coil 15a, the drive cycle T ₀ of the transmission coil 15a is detected, and the position detection device 20 detects the magnetic field for one position detection. It may be shorter than a period (hereinafter referred to as a detection period) T ₁ .

When the current flowing through the transmission coil 15a is controlled in this way, the S / N ratio of the detection signal output from the magnetic field detection unit 21 is as follows. FIG. 6 is a diagram showing a current level when the transmission coil 15a is always driven, and is shown for comparison.

Assuming that the voltage at both ends of the transmission coil 15a is V _C , the power consumption W _C0 in the magnetic field generator 150 is given by the following equation (1) when a current is continuously passed through the transmission coil 15a as shown in FIG.
W _C0 = V _C × I _C (1)

On the other hand, when the duty ratio is D (0 <D <1) , the case of repeating current on / off flow to the transmitter coil 15a as shown in FIG. 5 (current value I _0/0), the magnetic field generator 150 The power consumption W _C1 is given by the following equation (2).
W _C1 = V _C × I _C × D (2)
That is, the power consumption is suppressed by the duty ratio D.

As described above, the position detection accuracy of the capsule endoscope 10 depends on the S / N ratio of the detection signal. Therefore, the S / N ratio in the magnetic field detector 21 is calculated as follows when the alternating magnetic field is generated in each pattern of FIGS. 5 and 6.

First, when a current is constantly passed through the transmission coil 15a, if the signal level is S _C0 and the noise level is N _C0 , the S / N ratio is 20 × log (S _C0 / N _C0 ) (log is a common logarithm).

On the other hand, when switching on / off the current flowing through the transmission coil 15a, if the signal level is S _C1 and the noise level is N _C1 , the signal during the current off period is not used for position calculation. S _C1 becomes smaller than the signal level S _C0 by the duty ratio D. That is, S _C1 = S _C0 × D. Also, dominant factor in the noise level N _C1 is because the detection circuit of the position detecting device 20 side, the noise level N _C1 per hour is not the same as the noise level N _C0, narrow band by the amount of the duty ratio D Therefore, N _C2 = N _C0 × √D. Therefore, in this case, the S / N ratio is given by the following equation (3).

That is, when the transmission coil 15a is driven intermittently, the power consumption is reduced by the duty ratio D, but the S / N ratio is reduced only by the square root of the duty ratio D. For example, when the duty ratio is set to 50%, the decrease in the S / N ratio is limited to 20 × log√D≈−3 dB (≈71%). That is, in this case, compared with the case where the transmission coil 15a is continuously driven, the position detection accuracy per power consumption is increased, and the driving efficiency can be improved.

Further, when the current flowing through the transmission coil 15a is increased by the duty ratio D during the drive-on period of the transmission coil 15a, the power consumption W _C2 is given by the following equation (4).
W _C2 = V _C × (I _C / D) × D = V _C × I _C (4)

In this case, since the signal during the period in which the current value is zero is not used for position calculation, the signal level S _C2 has a duty ratio D as compared with the case where the transmission coil 15a is continuously driven as shown in the following equation (5). Decreases by the amount of.
S _C2 = (S _C0 / D) × D = S _C0 (5)

On the other hand, the noise level N _C2 is N _C0 × √D in order to switch on / off the current flowing through the transmission coil 15a.
Therefore, the S / N ratio in this case is given by the following equation (6).

In equation (6), 0 <D <1, so −log√D> 0. That is, when the transmission coil 15a is intermittently driven and the current flowing through the transmission coil 15a is increased by the duty ratio D, the power consumption is maintained while the transmission coil 15a is continuously driven. / N ratio can be improved.

In subsequent step S3, the alternating magnetic field generated from the capsule endoscope 10 is detected by each reception coil 21a of the magnetic field detection unit 21, and the detection signal output from each reception coil 21a is intermittently taken into the signal processing unit 26. .

7 to 9 are diagrams for explaining the capture timing of capturing the detection signal output from the magnetic field detection unit 21 into the signal processing unit 26. FIG. Here, when the signal processing unit 26 asynchronously captures the detection signal with respect to the detection signal output from the magnetic field detection unit 21 according to the alternating magnetic field generated from the capsule endoscope 10, the A / D conversion unit 263 or The FFT processing unit 282a cannot detect the section of the detection signal to be processed.

Therefore, in the first embodiment, for example, as shown in FIG. 7, the signal processing unit 26, and executes the signal acquisition operation a predetermined period T ₁ with a predetermined period T ₁ + T _2, the generation period of the alternating magnetic field as at least two capture period T ₁ is included in the tau _1, sets the generation period tau ₁ alternating magnetic field, the uptake period T _1, and the sampling intervals of T _2. That is, τ ₁ ≧ 2 × T ₁ + T ₂ is satisfied. By setting in this way, even if the signal processing unit 26 starts capturing signals before the alternating magnetic field is generated (before the detection signal is output from the magnetic field detection unit 21) (for example, timing t ₁ ). The next capturing timing (for example, timing t ₂ ) is always included in the alternating magnetic field generation period τ ₁ , so that reliable signal capturing can be performed.

Alternatively, as shown in FIG. 8, the signal processing unit 26 may start capturing the detection signal with the start of generation of an alternating magnetic field as a trigger. That is, after the state in which the magnetic field detection intensity in the magnetic field detection unit 21 is below a predetermined value continues for a certain period, the signal processing unit 26 starts to take in a detection signal when the value exceeds a predetermined value. Thereafter, when the detected intensity falls below a predetermined value or the period when the detected intensity falls below the predetermined value becomes equal to or longer than the predetermined period, the signal processing unit 26 stops capturing the detection signal. Alternatively, the capture may be stopped after a predetermined period has elapsed since the capture of the detection signal was started. The predetermined period in this case may be a period shorter than the preset alternating magnetic field generation period τ ₀ .

In this case, a time lag T _lag occurs from the start of the generation of the alternating magnetic field to the start of the detection signal capture by the signal processing unit 26. Therefore, a separate memory for temporarily storing all the detection signals output from the magnetic field detection unit 21 is provided, and after the signal processing unit 26 starts to capture the detection signal, the detection signal corresponding to the time lag T _lag is read from the memory. You may make it acquire retroactively.

Further, on the capsule endoscope 10 side, an alternating magnetic field that changes in a specific pattern may be generated as a trigger signal prior to the alternating magnetic field for position detection. For example, as shown in FIG. 9, when generating a trigger signal having two peaks, when the magnetic field detection unit 21 detects the two peaks, the signal processing unit 26 starts capturing the detection signal. The pattern of the trigger signal may be a short-term pattern having the same frequency as the alternating magnetic field for position detection, or may be a pattern that continues for a predetermined period at a frequency different from the alternating magnetic field for position detection. Further, the amplitude of the trigger signal may be smaller than the amplitude of the signal in the period T ₁ . Thereafter, when the detected intensity falls below a predetermined value or the period when the detected intensity falls below the predetermined value becomes equal to or longer than the predetermined period, the signal processing unit 26 stops capturing the detection signal. Alternatively, the capture may be stopped after a predetermined period has elapsed since the capture of the detection signal was started. Even in this case, the predetermined period may be shorter than the preset generation period of the alternating magnetic field.

Note that the signal processing unit 26 may also capture a detection signal in a period other than the generation period of the alternating magnetic field (that is, a period in which the detection intensity is lower than a predetermined value), and replace the signal value of the detection signal in the period with zero. . Also by this method, the signal processing unit 26 and the subsequent position information generation unit 282 can execute processing based only on the detection signal in the generation period of the alternating magnetic field.

In subsequent step S4, the signal processing unit 26 performs predetermined signal processing on the detection signal acquired from the magnetic field detection unit 21, that is, waveform shaping by the filter unit 261, amplification by the amplifier 262, and A / D conversion unit 263. By performing A / D conversion, detection data subjected to digital conversion is generated.

In subsequent step S <b> 5, the position information generation unit 282 generates position information of the capsule endoscope 10 using the detection data output from the signal processing unit 26. More specifically, first, the FFT processing unit 282a performs FFT processing on the detection data, thereby generating magnetic field information representing the strength and phase of the alternating magnetic field. Subsequently, the position calculation unit 282b estimates the distances from the plurality of reception coils 21a to the capsule endoscope 10 based on the magnetic field information, and calculates the position of the capsule endoscope 10 from these distances. . Note that the magnetic field information extracted by the FFT processing unit 282a may be further subjected to processing such as noise cut, and then input to the position calculation unit 282b.

Here, FIG. 10 is a diagram for explaining FFT window filter processing performed prior to the FFT processing in the FFT processing unit 282a. In the first embodiment, since the alternating magnetic field is intermittently generated from the capsule endoscope 10, the frequency distribution in the detection data is widened as compared with the case where the alternating magnetic field is continuous. Therefore, in order to correctly detect the alternating magnetic field, it is necessary to increase the reception bandwidth accordingly, but it also leads to an increase in noise.

In such a case, in general, in order to restore the envelope, in the alternating magnetic field generation period T ₀ , a band (−1 / τ ₁ ) corresponding to the period τ _{1 in} which the alternating magnetic field having the frequency F ₀ is generated. A filter is used that passes ~ (+ 1 / τ ₁ ), ie 2 / τ ₁ as the minimum required band. Since there is no filter that can completely cut the band, a roll-off filter is actually used.

However, in order to detect the position of the capsule endoscope 10, it is required to accurately detect the amplitude of the carrier wave component rather than the envelope information. The processing efficiency can be increased. Therefore, in the first embodiment, a filter that passes the band narrower than the bandwidth 2 / τ ₁ around the frequency F ₀ is used as the FFT window filter.

FIG. 11A is a graph showing the characteristics of a window function (Hamming window), which is an example of an FFT window filter, and FIG. 11B shows the frequency extracted by the FFT process on the signal after the FFT window filter process. It is a graph which shows a spectrum. In the horizontal axis of FIG. 11B, the coordinates of the center frequency F ₀ are set as a reference (= 0).

When detecting the amplitude of the carrier wave component, basically, it is only necessary to acquire a signal of the frequency F ₀ of the alternating magnetic field, so the sampling frequency is set for the frequency F ₀ . As a specific example, following the sampling theorem, if the sampling frequency is 2F ₀ , the sample length is N / 2F ₀ (N is an integer). If the capturing is stopped at the time of N = 1.0 after the start of capturing the detection data, the component of the frequency F ₀ can be acquired efficiently. That is, the sample length N / 2F ₀ may be set to be equivalent to the driving period τ ₁ . When the Hamming window shown in FIG. 11A is used, in the frequency spectrum shown in FIG. 11B, the bandwidth at an amplitude of −3 dB is 1.3 / τ ₁ .

Note that the FFT window is originally used to prevent erroneous detection called spectral leak due to waveform discontinuity caused by performing FFT analysis by forcibly cutting off aperiodic signals. However, since the FFT window is also a time waveform in which the beginning and end of the input signal are set to zero and the gap between them is gently detected, in addition to the Hamming window shown in FIG. Any data that can intentionally delete the frequency information of the rising and falling rectangular portions in the data can be used.

By performing such FFT window filter processing, only necessary signals can be extracted without waste by the FFT processing. Note that the filter processing for band limitation in this way is not limited to the preceding stage of the FFT processing, and may be performed by the signal processing unit 26. Or you may perform by the synthetic | combination process in a some block. In FIG. 10, the case where the drive period τ ₁ is shorter than the drive stop period τ ₂ has been described. Conversely, the drive stop period τ ₂ may be shorter. In this case, in the above description, τ ₁ and τ ₂ may be replaced.

In subsequent step S6, the control unit 28 causes the storage unit 27 to store the position information of the capsule endoscope 10 generated by the position information generation unit 282. Thereafter, the operation of the capsule medical system 1 ends.

As described above, according to the first embodiment, in the capsule endoscope 10, the alternating magnetic field is intermittently generated from the transmission coil 15a, so that the position detection of the capsule endoscope 10 in the position detection device 20 is performed. The power consumption of the power supply unit (battery) 140 can be suppressed without reducing the accuracy. Therefore, the operation time of the capsule endoscope 10 can be extended. In addition, since it is not necessary to apply a magnetic field for driving the transmission coil 15a from the outside, it is possible to prevent the capsule medical system 1 from being enlarged.

Further, according to the first embodiment, the position detection device 20 includes only detection signals in a period corresponding to the generation time of the alternating magnetic field among detection signals based on the alternating magnetic field generated intermittently from the capsule endoscope 10. Since the position of the capsule endoscope 10 is calculated based on the above, it is possible to reduce the total amount of processing in the signal processing unit 26 and the position information generation unit 282, improve processing efficiency, and suppress power consumption. It becomes possible.

(Modification 1)
Next, Modification 1 of Embodiment 1 will be described.
In the capsule endoscope 10, the driving cycle T ₀ of the transmission coil 15 a may be synchronized with the operations of the imaging unit 113 and the transmission unit 130. More specifically, as shown in FIG. 12, while the driving cycle T ₀ is set equal to the imaging cycle by the imaging unit 113 and the transmission cycle of the image data by the transmission unit 130 and imaging and transmission of the image data are performed, The transmission coil 15a is not driven. In this case, the maximum power consumption in the capsule endoscope 10 can be suppressed, and even if the power is supplied by a device that has a limit on the instantaneous maximum current consumption, such as a general battery, Electric power can be efficiently supplied to each part of the endoscope 10.

(Embodiment 2)
Next, a second embodiment of the present invention will be described.
In the first embodiment, an alternating magnetic field is intermittently generated from the capsule endoscope 10, and the position detection device 20 uses a detection signal in the period in which the alternating magnetic field is on among the detection signals of the alternating magnetic field. The position calculation process of the capsule endoscope 10 was performed. However, the capsule endoscope 10 and the position detection device 20 are separate from each other and cannot be controlled with a common clock. For this reason, the delay time between the drive timing of the transmission coil 15a (the generation timing of the alternating magnetic field) and the completion timing of the position calculation process may change from time to time. For example, as shown in FIG. 13, when the alternating magnetic field generation period T ₀ and the alternating magnetic field detection period _TDTC are different, the difference between the position calculation start timing and the end point of the magnetic field generation period accumulates, and the delay time T _DL changes. In the second embodiment, the generation of the alternating magnetic field is turned on after the start of one detection period _TDTC of the alternating magnetic field (if it has already occurred, from the start of the detection period _TDTC ). ), The position calculation is performed based on the magnetic field information at the intermediate time t _MID of the period ΔT until it is turned off, and the difference between the intermediate time t _MID and the time when the position calculation process started thereafter is ended is the delay time. _TDL .

However, when the position information of the capsule endoscope 10 calculated in the position detection device 20 is fed back and used for position control of the capsule endoscope 10, the delay time _TDL is constant and shorter. preferable. Further, in the capsule endoscope 10, there is also a delay in the generation time of the alternating magnetic field with respect to the imaging time, so that the delay time T _DL on the position detection device 20 side also varies or the delay time T _DL is If it becomes longer, it becomes impossible to accurately grasp the position of the capsule endoscope 10 at the time of capturing an in-vivo image.

Therefore, in the second embodiment, the delay time T _DL is constant by capturing the detection signal in synchronization with the generation timing of the alternating magnetic field based on the signal value of the detection signal output from the magnetic field detection unit 21. And shortening.

FIG. 14 is a block diagram illustrating a configuration of a signal processing unit included in the position detection device according to the second embodiment. The position detection device according to the second embodiment includes a signal processing unit 26-2 shown in FIG. 14 instead of the signal processing unit 26 of the position detection device main body 22 shown in FIG. The configuration of the entire capsule medical system according to the second embodiment and the configuration of the capsule endoscope 10 are the same as those of the first embodiment.

In addition to the filter unit 261, the amplifier 262, and the A / D conversion unit 263, the signal processing unit 26-2 includes a memory 264 that temporarily stores the digitally converted detection data, and an intermittent alternating magnetic field based on the detection data. An intermittent timing detection unit 265 that detects timing is provided. In the second embodiment, the FFT processing unit 282a extracts magnetic field information such as the amplitude and phase of the alternating magnetic field from the detection data in synchronization with the generation timing of the alternating magnetic field based on the detection result of the intermittent timing detection unit 265. The position information generation unit 282 (see FIG. 1) calculates the position of the capsule endoscope 10 based on the data (magnetic field information) output from the signal processing unit 26-2.

Next, the operation of the intermittent timing detection unit 265 will be described in detail.
(1) When signal processing is performed in synchronization with the rising of an alternating magnetic field The intermittent timing detection unit 265 has a signal value of a detection signal output from one or more reception coils 21a of the magnetic field detection unit 21 as a predetermined threshold value. When this is the case, the generation of an alternating magnetic field is detected.

Subsequently, as shown in FIG. 15, the intermittent timing detection unit 265 causes the memory 264 to store the detection data acquired during a predetermined detection period _TDTC in synchronization with the rising timing of the detection signal of the alternating magnetic field. . FFT processing section 282a after the lapse of the detection period T _DTC, during which extracts magnetic-field information of the alternating magnetic field by performing FFT processing on the detection data stored in the memory 264, the position calculating unit 282b is extracted The position of the capsule endoscope 10 is calculated based on the magnetic field information.

In this case, since the difference between the position calculation start timing including the FFT processing and the end point of the alternating magnetic field generation period is constant, the delay time _TDL is also stabilized. Note that the length of the delay time _TDL itself depends on the length of the detection period _TDTC .

(2) When signal processing is performed in synchronization with the fall of the alternating magnetic field In this case, output data from the A / D converter 263 is sequentially stored in the memory 264.
The intermittent timing detection unit 265 detects the alternating magnetic field when the signal values of the detection signals output from all the reception coils 21a of the magnetic field detection unit 21 are less than a predetermined threshold (or substantially zero) for a predetermined period. Detection of occurrence stop. The period serving as a judgment criterion at this time is set in advance so as to be 1/4 or more of the generation period of the alternating magnetic field. This avoids erroneous detection when the phase in the alternating magnetic field becomes zero.

Subsequently, as shown in FIG. 16, the intermittent timing detection unit 265 reads detection data for a predetermined detection period _TDTC retrospectively from the memory 264 in synchronization with the fall timing of the detection signal of the alternating magnetic field. The FFT processing unit 282a extracts the magnetic field information of the alternating magnetic field by performing FFT processing on the detection data read from the memory 264 during this period, and the position calculation unit 282b performs the capsule based on the extracted magnetic field information. The position of the mold endoscope 10 is calculated.

In this case, since the difference between the position calculation start timing including the FFT processing and the end point of the alternating magnetic field generation period is constant (simultaneous), the delay time _TDL is also stable. Further, since the position calculation can be started simultaneously with the fall of the detection signal of the alternating magnetic field, the delay time _TDL becomes the shortest.

In the above cases (1) and (2), the threshold for determining the rise and fall of the detection signal of the alternating magnetic field may be determined from the noise level in the output signal of the magnetic field detection unit 21. Or it determines from the maximum value of the output signal from the magnetic field detection part 21 when the capsule endoscope 10 which is a position detection object is not arrange | positioned in detection space (area | region which can detect a magnetic field by the magnetic field detection part 21). May be.

As described above, according to the second embodiment, the position calculation is performed in synchronization with the rising or falling edge of the detection signal of the alternating magnetic field. Therefore, the delay time _TDL from the generation of the magnetic field to the end of the position calculation process is constant. Can be. Further, when processing is performed in synchronization with the fall of the detection signal, the delay time _TDL can be minimized.

(Modification 2-1)
Next, in the capsule endoscope 10, when changing the duty ratio when the transmission coil 15a is intermittently driven, that is, as shown in FIG. 17, the generation periods T _a , T _b , T _c of the alternating magnetic field are A case where they are different from each other will be described. In this case, the intermittent timing detector 265, in synchronization with the falling edge of the detection signal, reads out the detection data of a predetermined detection period T _DTC from the memory 264. The FFT processing unit 282a extracts the magnetic field information by performing FFT processing on the detection data read from the memory 264 during this period, and the position calculation unit 282b extracts the capsule-type endoscope based on the extracted magnetic field information. The position of the mirror 10 is calculated.

However, in this case, the delay time _TDL changes according to the change of the duty ratio. Therefore, as shown in FIG. 18, the intermittent timing detection unit 265 detects both rising and falling of the detection signal of the alternating magnetic field, calculates the duty ratio, and outputs the position calculation result according to each duty ratio. The delay time _TDL is made constant by delaying the timing. Specifically, the output timing of the magnetic field information from the FFT processing unit 282a to the position calculation unit 282b may be delayed, or the output timing of the position calculation result from the position calculation unit 282b may be delayed.

(Modification 2-2)
In the capsule endoscope 10, the intermittent drive timing of the transmission coil 15a may be synchronized with the imaging timing of the imaging unit 113. That is, imaging within the subject 2 and generation of an alternating magnetic field for position detection are performed simultaneously. In this case, the delay time between the generation timing of the image data by the imaging unit 113 and the calculation timing of the position information based on the alternating magnetic field generated from the transmission coil 15a can be shortened.

(Embodiment 3)
Next, a third embodiment of the present invention will be described.
In the capsule endoscope 10 (see FIG. 2), when the light emitting element (LED) of the illuminating unit 111 is driven, the power supply voltage temporarily decreases, and the output of the alternating magnetic field generated from the transmission coil 15a decreases. May end up. However, in the position detection device 20, since the signal strength of the alternating magnetic field detected within a predetermined period is averaged and used, if averaging is performed between the normal output and the temporarily reduced output, the capsule type The position detection accuracy of the endoscope 10 may be reduced. Therefore, in the third embodiment, the power supply unit 140 prevents the capsule endoscope 10 from affecting the position detection accuracy even when the power supply voltage is lowered in the capsule endoscope 10. The control unit 120 controls the input of the voltage to the magnetic field generation unit 150.

(Control example 1)
FIG. 19 is a schematic diagram illustrating a configuration of a capsule endoscope used in the first control example. A capsule endoscope 10A illustrated in FIG. 19 further includes a voltage detection unit 160 that detects the voltage value of the power supply unit 140 with respect to the capsule endoscope 10 illustrated in FIG. The voltage value (hereinafter also referred to as power supply voltage) of the power supply unit 140 detected by the voltage detection unit 160 is input to the control unit 120.

As shown in FIG. 20, when the power supply voltage (VCC) decreases due to light emission (ON) of the LED and the power supply voltage becomes less than a predetermined threshold Th, the control unit 120 supplies power to the magnetic field generation unit 150. Turn off the supply. Further, when the power supply voltage recovers to the threshold value or more, the control unit 120 turns on the power supply to the magnetic field generation unit 150.

Thereby, in the position detection device 20, the position of the capsule endoscope 10A can be calculated based only on a stable detection signal within the generation period of the alternating magnetic field. Accordingly, it is possible to accurately detect the position of the capsule endoscope 10A.

(Control example 2)
As shown in FIG. 21, the control unit 120 switches on / off the power supply to the magnetic field generation unit 150 in synchronization with the light emission timing of the LED. That is, the power supply to the magnetic field generation unit 150 is turned off at the timing when the power supply voltage starts to decrease due to the light emission of the LED, and the power supply to the magnetic field generation unit 150 is started at the time when the power supply voltage is restored after the light emission of the LED is finished. Turn on.

Also in this case, the position detection device 20 can calculate the position of the capsule endoscope 10A based only on the stable detection signal within the generation period of the alternating magnetic field, and the position of the capsule endoscope 10A can be calculated. It becomes possible to detect accurately.

(Control example 3)
As shown in FIG. 22, the light emission timing of the LED and the timing at which the power supply voltage decreases are not necessarily the same. Therefore, the control unit 120 synchronizes on / off switching of the power supply to the magnetic field generation unit 150 with the light emission timing of the LED, and sets the power supply off period longer than the light emission period of the LED. The power supply off period may be a predetermined period after the start of light emission of the LED, or may include the light emission period of the LED and a predetermined period before and after the light emission period.

As described above, by taking the output off period of the alternating magnetic field longer than the light emission period of the LED, the position detection device 20 can execute the position calculation process based only on the more stable detection signal.

(Control example 4)
As shown in FIG. 23, the control unit 120 detects the rise of the light emission of the LED, and turns off the power supply to the magnetic field generation unit 150 in accordance with the rise timing. Thereafter, power supply to the magnetic field generation unit 150 is turned on after a predetermined time longer than the light emission time of the LED has elapsed.

As described above, the position detection device 20 efficiently executes the position calculation process based on only the more stable detection signal by turning off the output of the alternating magnetic field in all the periods during which the LEDs actually emit light. Can do.

(Control example 5)
On the position detection device 20 side, the FFT processing unit 282a optimizes the FFT processing result by using a window function. That is, the position calculation is not performed using all the detection signals of the alternating magnetic field generated by the magnetic field generator 150. Therefore, as shown in FIG. 24, in the capsule endoscope 10A, the LED may be caused to emit light at a timing at which the alternating magnetic field detection signal is not used for position calculation. In other words, the alternating magnetic field is not detected for a predetermined time before and after the LED light emission timing.

For this purpose, for example, the signal level of the alternating magnetic field is directly detected by the capsule endoscope 10A, and when the signal level falls below a predetermined level, or the time when the signal level falls below the predetermined level is a predetermined length. When it continues, the LED may emit light. Alternatively, a synchronization signal may be separately transmitted from the outside to the capsule endoscope 10A, and the LED may emit light in synchronization with the synchronization signal. In these cases, the position detection device 20 can perform position calculation using only the detection signal within a period during which the magnetic field output is stable, so that accurate position information can be acquired.

In the control examples 1 to 5, the power supply to the magnetic field generation unit 150 is synchronized with the light emission timing of the LED, but is synchronized with the imaging timing of the imaging unit 113 and the transmission timing of the wireless signal from the transmission unit 130. You may let them. In this case, it is possible to reduce the influence of the decrease in the magnetic field output due to the decrease in the power supply voltage caused by the driving of the image sensor and the transmission of the wireless signal on the position calculation process.

(Modification 3)
The arrangement of the transmission coil 15a in the

capsule endoscopes

10 and 10A described in the first to third embodiments is not particularly limited as long as the effective area of the transmission coil 15a can be increased without obstructing the field of view of the imaging unit 113. It is not limited. FIG. 25 is a side view showing a first arrangement example of the transmission coil 15a. As shown in FIG. 25, the direction of the central axis of the transmission coil 15 a may be aligned with the long axis of the housing 101, and the transmission coil 15 a may be wound along the outer periphery of the trunk portion 102. In this case, the effective area S of the transmission coil 15a indicated by the alternate long and short dash line can be made larger than when the transmission coil 15a is wound around the inner periphery of the body portion 102, and the efficiency of the coil can be increased.

FIG. 26 is a side view showing a second arrangement example of the transmission coil 15a. As shown in FIG. 26, the transmission coil 15 a may be wound around the outer periphery of the body portion 102 so that the central axis of the transmission coil 15 a is inclined with respect to the long axis of the housing 101. In this case, the effective area S of the transmission coil 15a can be further increased.

FIG. 27 is a side view showing a third arrangement example of the transmission coil 15a. FIG. 28 is a side view showing a fourth arrangement example of the transmission coil 15a. When the transmission coil 15 a is wound so that the central axis of the transmission coil 15 a is inclined with respect to the long axis of the housing 101, the transmission coil 15 a may be applied to the

dome parts

103 and 104 at both ends of the body part 102. . At this time, when the imaging units 113 are provided at both ends of the

capsule endoscopes

10 and 10A, respectively, as shown in FIG. 27, the dome unit 103, The transmission coil 15a may be wound around the vicinity of the central portion 104. On the other hand, when the imaging unit 113 is provided only at one end (for example, the dome 103 side) of the capsule endoscope, as shown in FIG. 28, the dome unit 104 side where the imaging unit is not arranged is provided. The center portion of the dome 104 may be covered with the transmission coil 15a.

FIG. 29 (a) is a side view showing a fifth arrangement example of the transmission coil 15a, and FIG. 29 (b) is a perspective view thereof. Here, the transmission coil 15a is not necessarily wound on the same plane. For example, as shown in FIG. 29, the transmitting coil 15a is wound only half a circumference along the outer periphery at one end of the trunk portion 102, and is extended to the other end along the central axis direction of the trunk portion 102. A winding method is also possible in which the winding is performed only half a circumference along the outer circumference of the portion 102 different from the one end side, and then extended to one end of the trunk portion 102 along the central axis direction of the trunk portion 102. In this case, the effective area S of the transmission coil 15a can be further increased.

30 (a) is a side view showing a sixth arrangement example of the transmission coil 15a, and FIG. 30 (b) is a perspective view thereof. In this arrangement example, unlike the fifth arrangement example, at both ends of the body portion 102, the transmission coil 15a is wound around the same side by a half circumference. Also in this case, the effective area S of the transmission coil 15a can be widened.

The embodiments and modifications described above are merely examples for carrying out the present invention, and the present invention is not limited to these. Moreover, the present invention can generate various inventions by appropriately combining a plurality of constituent elements disclosed in the respective embodiments and modifications. It is obvious from the above description that the present invention can be variously modified according to specifications and the like, and that various other embodiments are possible within the scope of the present invention.

(Appendix 1)
In a capsule medical system including a capsule medical device that is introduced into a subject and generates a magnetic field for position detection, and a position detection device that detects the position of the capsule medical device based on the magnetic field. A capsule-type medical device used,
Battery,
Magnetic field generating means for generating a magnetic field by receiving power from the battery;
Control means for controlling power supply from the battery to the magnetic field generating means;
Information that includes illumination means for illuminating the inside of the subject and imaging means for imaging the inside of the subject illuminated by the illumination means, and receives information about the inside of the subject by receiving power from the battery Acquisition means;
With
The control means performs control so that power is intermittently supplied from the battery to the magnetic field generation means according to the operation of the illumination means.
A capsule-type medical device.

(Appendix 2)
In a capsule medical system including a capsule medical device that is introduced into a subject and generates a magnetic field for position detection, and a position detection device that detects the position of the capsule medical device based on the magnetic field. A capsule-type medical device used,
Battery,
Magnetic field generating means for generating a magnetic field by receiving power from the battery;
Control means for controlling power supply from the battery to the magnetic field generating means;
An image acquisition unit that captures an image of the inside of the subject to generate image data; and an information acquisition unit that receives information about the inside of the subject by receiving power from the battery;
Transmitting means for wirelessly transmitting the image data generated by the imaging means;
With
The control means performs control so that power is intermittently supplied from the battery to the magnetic field generation means according to at least one operation of the imaging means and the transmission means.
A capsule-type medical device.

(Appendix 3)
A capsule medical device that is introduced into a subject and used to generate a magnetic field for position detection,
Battery,
Magnetic field generating means for generating a magnetic field by receiving power from the battery;
Control means for controlling power supply from the battery to the magnetic field generating means;
Information acquisition means for receiving information about the inside of the subject by receiving power from the battery;
A capsule medical device comprising:
A position detection device that detects the position of the capsule medical device based on the magnetic field,
Magnetic field detection means for detecting a magnetic field generated by the magnetic field generation means and outputting a detection signal;
Processing means for executing processing for calculating the position of the capsule medical device based on the detection signal output by the magnetic field detection means;
A position detecting device having
With
The control means performs control so that power is intermittently supplied from the battery to the magnetic field generation means in synchronization with the operation of the information acquisition means.
Capsule type medical system characterized by that.

(Appendix 4)
The capsule medical system according to appendix 3, wherein the processing means executes the processing when a magnetic field having a strength equal to or greater than a predetermined value is detected by the magnetic field detection means.

(Appendix 5)
A capsule medical device that is introduced into a subject and used.
Battery,
Magnetic field generating means for generating a magnetic field by receiving power from the battery;
Control means for controlling power supply from the battery to the magnetic field generating means;
A capsule-type medical device having
A position detection device for detecting a position of the capsule medical device,
Magnetic field detection means for detecting a magnetic field generated by the magnetic field generation means and outputting a detection signal;
Processing means for executing processing for calculating the position of the capsule medical device based on the detection signal output by the magnetic field detection means;
A position detecting device having
With
The control means performs control so that power is intermittently supplied from the battery to the magnetic field generation means,
The processing means starts the processing when the magnetic field detection means detects a magnetic field exceeding a predetermined intensity, and detects a detection signal whose intensity is a predetermined value or more among detection signals output from the magnetic field detection means. To perform the process using
Capsule type medical system characterized by that.

(Appendix 6)
A capsule medical device that is introduced into a subject and used.
The capsule medical device is:
Battery,
Magnetic field generating means for generating a magnetic field by receiving power from the battery;
Control means for controlling power supply from the battery to the magnetic field generating means;
Information acquisition means for acquiring information relating to the inside of the subject;
A capsule-type medical device having
A position detection device for detecting a position of the capsule medical device,
Magnetic field detection means for detecting a magnetic field generated by the magnetic field generation means and outputting a detection signal;
Processing means for executing processing for calculating the position of the capsule medical device based on the detection signal output by the magnetic field detection means;
A position detecting device having
With
The control means intermittently supplies power from the battery to the magnetic field generation means while the information acquisition means is not operating.
Capsule type medical system characterized by that.

(Appendix 7)
A capsule medical device that is introduced into a subject and used.
The capsule medical device is:
Battery,
Magnetic field generating means for generating a magnetic field by receiving power from the battery;
Control means for controlling power supply from the battery to the magnetic field generating means;
Information acquisition means for acquiring information relating to the inside of the subject;
A capsule-type medical device having
A position detection device for detecting a position of the capsule medical device,
Magnetic field detection means for detecting a magnetic field generated by the magnetic field generation means and outputting a detection signal;
Processing means for executing processing for calculating the position of the capsule medical device based on the detection signal output by the magnetic field detection means;
A position detecting device having
With
The control means intermittently supplies power from the battery to the magnetic field generation means while the information acquisition means is operating.
Capsule type medical system characterized by that.

(Appendix 8)
The information acquisition means includes imaging means for imaging the inside of the subject and generating image data,
The capsule medical system according to appendix 6 or 7, wherein the capsule medical device further includes a transmission unit that wirelessly transmits the image data generated by the imaging unit.

(Appendix 9)
A capsule medical device that is introduced into a subject and used.
The capsule medical device is:
Battery,
Magnetic field generating means for receiving an electric power supply from the battery to generate an alternating magnetic field;
Control means for controlling power supply from the battery to the magnetic field generating means;
A capsule-type medical device having
A position detection device for detecting a position of the capsule medical device,
Magnetic field detection means for detecting an alternating magnetic field generated by the magnetic field generation means and outputting a detection signal;
Processing means for executing processing for calculating the position of the capsule medical device based on the detection signal output by the magnetic field detection means;
A position detecting device having
With
The control means performs control so that power is intermittently supplied from the battery to the magnetic field generation means,
The processing means includes filter means for allowing a signal in a frequency band having a predetermined bandwidth including a center frequency of the alternating magnetic field to pass through the detection signal.
Capsule type medical system characterized by that.

(Appendix 10)
The processing means includes FFT processing means for performing a fast Fourier transform process on the detection signal,
The filter means is a window function filter provided in the previous stage of the FFT processing means,
The capsule medical system according to appendix 9, wherein the frequency band of the window function in the window function filter is narrower than 2 / τ ₁ when the generation period of the alternating magnetic field per cycle is τ ₁ .

(Appendix 11)
A position detection device that detects the position of a capsule medical device that is introduced into a subject and used to generate a magnetic field by receiving power from a built-in battery,
The capsule medical device intermittently generates the magnetic field,
Magnetic field detection means for detecting a magnetic field generated from the capsule medical device and outputting a detection signal;
Processing means for executing processing for calculating the position of the capsule medical device based on the detection signal output by the magnetic field detection means;
With
The processing means detects at least one of a rising timing and a falling timing of the detection signal according to the magnetic field generated intermittently, and starts the processing.
A position detecting device characterized by that.

(Appendix 12)
The position according to appendix 11, wherein the processing means executes the processing using a detection signal output from the magnetic field detection means within a predetermined period following detection of a rising timing of the detection signal. Detection device.

(Appendix 13)
A storage means for storing the detection signal output from the magnetic field detection means;
The processing means, after detecting the falling timing of the detection signal, acquires the detection signal of a period before the falling timing by a predetermined period from the storage means, and uses the acquired detection signal Execute the process,
Item 7. The position detection device according to appendix 6, wherein

DESCRIPTION OF SYMBOLS 1 Capsule type medical system 2

Subject

10, 10A Capsule type endoscope 101 Case 102

Body part

103, 104 Dome part 110 Imaging unit 111 Illumination part 112 Optical system 113 Imaging part 120 Control part 130 Transmission part 140 Power supply part 150 Magnetic field Generating unit 15a Transmitting coil 15b Capacitor 151 Resonant circuit 152 Signal generating unit 153 Driving unit 160 Voltage detecting unit 20 Position detecting device 21 Magnetic field detecting unit 21a Receiving coil 22 Position detecting device main body 23 Input unit 24 Output unit 25 Receiving unit 25a Antenna 26, 26-2 Signal processing unit 261 Filter unit 262 Amplifier 263 A / D conversion unit 264 Memory 265 Intermittent timing detection unit 27 Storage unit 28 Control unit 281 Image processing unit 282 Position information generation unit 282a FFT processing unit 282b Position calculation unit 3 Mounting table

Claims

In a capsule medical system including a capsule medical device that is introduced into a subject and generates a magnetic field for position detection, and a position detection device that detects the position of the capsule medical device based on the magnetic field. A capsule-type medical device used,
Battery,
Magnetic field generating means for generating a magnetic field by receiving power from the battery;
Control means for controlling power supply from the battery to the magnetic field generating means;
Information acquisition means for receiving information about the inside of the subject by receiving power from the battery;
With
The capsule medical device, wherein the control unit performs control so that power is intermittently supplied from the battery to the magnetic field generation unit in synchronization with the operation of the information acquisition unit.
Voltage detection means for detecting the voltage value of the battery,
2. The control unit according to claim 1, wherein the control unit stops power supply from the battery to the magnetic field generation unit during a period in which the voltage value is less than a predetermined threshold based on a detection result by the voltage detection unit. The capsule medical device described.
The capsule medical device according to claim 1, wherein the control unit stops power supply from the battery to the magnetic field generation unit during an operation period of the information acquisition unit.
The control unit stops power supply from the battery to the magnetic field generation unit during an operation period of the information acquisition unit and at least one predetermined period before and after the operation period. Item 2. A capsule medical device according to Item 1.
2. The control unit according to claim 1, wherein the control unit detects an operation start timing of the information acquisition unit, and stops power supply from the battery to the magnetic field generation unit for a predetermined period from the operation start timing. Capsule type medical device.
A capsule medical device that is introduced into a subject and used.
Battery,
Magnetic field generating means for generating a magnetic field by receiving power from the battery;
Control means for controlling power supply from the battery to the magnetic field generating means;
A capsule-type medical device having
A position detection device for detecting a position of the capsule medical device,
Magnetic field detection means for detecting a magnetic field generated by the magnetic field generation means and outputting a detection signal;
Processing means for executing processing for calculating the position of the capsule medical device based on the detection signal output by the magnetic field detection means;
A position detecting device having
With
The capsule medical system according to claim 1, wherein the control means performs control such that power is intermittently supplied from the battery to the magnetic field generating means.
The capsule medical system according to claim 6, wherein the processing means executes the processing using a detection signal having an intensity equal to or higher than a predetermined value among detection signals output from the magnetic field detection means.
When the control means starts power supply from the battery to the magnetic field generation means, the control means executes power supply in a specific pattern indicating the start,
The capsule medical system according to claim 7, wherein the processing unit starts the processing when the magnetic field detection unit detects a magnetic field that changes in the pattern.
The capsule medical system according to claim 7, wherein the processing means detects at least one of a rising timing and a falling timing of the detection signal and starts the processing.
10. The capsule according to claim 9, wherein the processing unit executes the processing by using the detection signal output from the magnetic field detection unit within a predetermined period following detection of the rising timing of the detection signal. Type medical system.
The position detection device further includes storage means for storing the detection signal output from the magnetic field detection means,
The processing means, after detecting the falling timing of the detection signal, acquires the detection signal of a period before the falling timing by a predetermined period from the storage means, and uses the acquired detection signal The capsule medical system according to claim 9, wherein the process is executed.
7. The processing unit according to claim 6, wherein the processing unit executes the processing by replacing a signal value of a detection signal whose intensity is smaller than a predetermined value among detection signals output from the magnetic field detection unit with zero. The capsule medical system as described.
The processing means executes the processing for a predetermined period at a predetermined cycle,
The capsule type according to claim 6, wherein the length of one period during which electric power is supplied from the battery to the magnetic field generating means is equal to or longer than a period in which the processing means executes the processing twice. Medical system.
The processing includes fast Fourier transform processing for the detection signal,
The processing means executes the processing for a predetermined period at a predetermined cycle,
The length of one period during which power is supplied from the battery to the magnetic field generation unit is equal to or longer than a period in which the processing unit executes the fast Fourier transform process twice. Capsule medical system.
The capsule medical device is:
A casing having a cylindrical barrel portion and at least one dome portion provided at an end portion of the barrel portion;
Imaging means for imaging the outside of the housing from the inside of the housing via the at least one dome portion;
Further comprising
The magnetic field generating means includes a coil that generates a magnetic field when a current flows, and a driving means that drives the coil;
Have
The coil is wound around the axis inclined with respect to the central axis of the housing and having a diameter larger than the diameter of the body part and does not interfere with the field of view of the imaging unit, or A portion wound around the outer periphery of the housing and parallel to the central axis of the body portion, and a portion along the circumferential direction of the body portion,
The capsule medical system according to any one of claims 6 to 14, wherein: