Capsule type medical device

BACKGROUND OF THE INVENTION

1. Field of the Invention

0001The present invention relates to medical systems and, in particular, to a medical system having a capsule type medical device that performs a medical examination and/or a medical treatment in a living body.

2. Description of the Related Art

0002Capsule type medical devices for performing a medical examination and/or a medical treatment in a living body have been proposed. <patcit id="pcit0001" dnum="WO0135813A1"><text>Patent application PCT WO 01-35813A1</text></patcit> discloses a technique in which a capsule type medical device easy for patients to swallow is used to collect medical images.

0003In accordance with this technique, the capsule type medical device is housed in a package, and is attached to the package with a magnet prior to use. When the capsule type medical device is used for collecting images, the capsule type medical device is taken out of the package. If the capsule type medical device is removed from the package, the magnetic field of the magnet affects a power supply in the capsule type medical device, thereby causing the power supply to be switched on.

0004<patcit id="pcit0002" dnum="JP2849131B"><text>Japanese Patent 2849131</text></patcit> discloses an ultrasonic diagnostic imaging technique in which the power of a capsule type medical device is switched on or off in response to a trigger signal from the outside. <patcit id="pcit0003" dnum="JP2224650A"><text>JP 02-224650</text></patcit> discloses a capsule medical device having means for switching on and off the power to the capsule medical device via a trigger.

SUMMARY OF THE INVENTION

0005A medical system of the present invention includes a capsule type medical device according to claim 1. The capsule type medical device may have a capsule configuration, an operation device, arranged external to the capsule type medical device, and including a generating circuit for generating a particular pattern signal, a switch, arranged in the capsule type medical device, for switching on and off power of the capsule type medical device, a receiver, arranged in the capsule type medical device, for receiving a signal from the outside, and a pattern monitoring unit, arranged in the capsule type medical device, for turning on or off the switch at the moment the pattern monitoring unit detects a particular pattern signal as an output signal from the receiver.

0006Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The features and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

0007<ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">Fig. 1</figref> is a block diagram illustrating the entire structure of a medical system in accordance with a first embodiment of the present invention;</li><li><figref idref="f0002">Fig. 2</figref> is a sectional view illustrating the internal structure of a capsule type medical device of the first embodiment;</li><li><figref idref="f0003">Fig. 3</figref> is a circuit diagram illustrating a power switch circuit in the capsule type medical device in accordance with the first embodiment of the present invention;</li><li><figref idref="f0004">Fig. 4A</figref> is a time chart illustrating the operation of the power switch circuit in the capsule type medical device in accordance with the first embodiment of the present invention;</li><li><figref idref="f0004">Fig. 4B</figref> is a time chart illustrating the operation of the power switch circuit in the capsule type medical device in accordance with the first embodiment of the present invention;</li><li><figref idref="f0004">Fig. 4C</figref> is a time chart illustrating the operation of the power switch circuit in the capsule type medical device in accordance with the first embodiment of the present invention;</li><li><figref idref="f0004">Fig. 4D</figref> is a time chart illustrating the operation of the power switch circuit in the capsule type medical device in accordance with the first embodiment of the present invention;</li><li><figref idref="f0004">Fig. 4E</figref> is a time chart illustrating the operation of the power switch circuit in the capsule type medical device in accordance with the first embodiment of the present invention;</li><li><figref idref="f0004">Fig. 4F</figref> is a time chart illustrating the operation of the power switch circuit in the capsule type medical device in accordance with the first embodiment of the present invention;</li><li><figref idref="f0004">Fig. 4G</figref> is a time chart illustrating the operation of the power switch circuit in the capsule type medical device in accordance with the first embodiment of the present invention;</li><li><figref idref="f0004">Fig. 4H</figref> is a time chart illustrating the operation of the power switch circuit in the capsule type medical device in accordance with the first embodiment of the present invention;</li><li><figref idref="f0004">Fig. 4I</figref> is a time chart illustrating the operation of the power switch circuit in the capsule type medical device in accordance with the first embodiment of the present invention;</li><li><figref idref="f0005">Fig. 5</figref> is a block diagram illustrating the entire structure of the medical system in accordance with a second embodiment of the present invention;</li><li><figref idref="f0006">Fig. 6</figref> is a block diagram illustrating the entire structure of the medical system in accordance with a third embodiment of the present invention;</li><li><figref idref="f0007">Fig. 7A</figref> is a time chart illustrating the operation of the power switch circuit in the capsule type medical device in accordance with the third embodiment of the present invention;</li><li><figref idref="f0007">Fig. 7B</figref> is a time chart illustrating the operation of the power switch circuit in the capsule type medical device in accordance with the third embodiment of the present invention;</li><li><figref idref="f0007">Fig. 7C</figref> is a time chart illustrating the operation of the power switch circuit in the capsule type medical device in accordance with the third embodiment of the present invention;</li><li><figref idref="f0007">Fig. 7D</figref> is a time chart illustrating the operation of the power switch circuit in the capsule type medical device in accordance with the third embodiment of the present invention;</li><li><figref idref="f0007">Fig. 7E</figref> is a time chart illustrating the operation of the power switch circuit in the capsule type medical device in accordance with the third embodiment of the present invention;</li><li><figref idref="f0007">Fig. 7F</figref> is a time chart illustrating the operation of the power switch circuit in the capsule type medical device in accordance with the third embodiment of the present invention;</li><li><figref idref="f0007">Fig. 7G</figref> is a time chart illustrating the operation of the power switch circuit in the capsule type medical device in accordance with the third embodiment of the present invention;</li><li><figref idref="f0007">Fig. 7H</figref> is a time chart illustrating the operation of the power switch circuit in the capsule type medical device in accordance with the third embodiment of the present invention; and</li><li><figref idref="f0007">Fig. 7I</figref> is a time chart illustrating the operation of the power switch circuit in the capsule type medical device in accordance with the third embodiment of the present invention.</li></ul>

DETAILED DESCRIPTION OF THE EMBODIMENTS

0008The embodiments of the present invention will now be discussed with reference to the drawings.

0009<figref idref="f0001 f0002 f0003">Figs. 1-3</figref> and <figref idref="f0004">Figs. 4A-4I</figref> illustrate a medical system in accordance with a first embodiment of the present invention.

0010Referring to <figref idref="f0001">Fig. 1</figref>, the medical system 1 of the first embodiment of the present invention includes a capsule type medical device 2 that collects biomedical information in the body cavity, such as image information when a patient swallows the capsule type medical device 2, a remote controller 3, arranged external to the patient body, for issuing a power on/off command to the capsule type medical device 2, and an external recording device 4 that receives, and records and/or displays the image information acquired from the capsule type medical device 2.

0011The capsule type medical device 2 in accordance with the first embodiment of the present invention houses a battery 7 within a capsule container 6. The power of the battery 7 is fed to the load circuit 9 through the power switch circuit 8. The power switch circuit 8 switches on or off the power of the battery 7.

0012The power switch circuit 8 employs a magnetic sensor 11 that detects magnetism (a magnetic field). The remote controller 3 includes an electromagnet 12 that generates a magnetic field to be detected by the magnetic sensor 11.

0013The remote controller 3 generates a predetermined magnetic pattern signal, thereby causing the power switch circuit 8 to be shifted from an off state to an on state.

0014A remote controller 3 of <figref idref="f0001">Fig. 1</figref> includes a battery 13, a switch 14 for issuing a power on command, a pattern generator circuit 15 for generating a predetermined pattern driving signal in response to the operation of the switch 14, and an electromagnet 12 for generating a magnetism pattern signal corresponding to the pattern driving signal. The pattern driving signal is a digital driving signal of a signal level 0 or 1. The electromagnet 12 generates magnetism in response to the level 1 pattern driving signal while not generating magnetism in response to the level 0 pattern driving signal.

0015The power switch circuit 8 housed in the capsule type medical device 2 includes the magnetic sensor 11 for detecting the presence or absence of magnetism of the magnetism pattern (binarized magnetism pattern) generated by the electromagnet 12, a switch driver circuit 16 that is set to be operative in response to the presence of magnetism detected by the magnetic sensor 11, a semiconductor switch 17 that is on/off controlled by the switch driver circuit 16, and a pattern monitoring circuit 18 that monitors the magnetism pattern to determine whether or not the magnetism pattern matches a predetermined pattern.

0016The pattern generator circuit 15 generates a pattern signal in synchronization with a clock signal having a predetermined frequency. The pattern monitoring circuit 18 monitors the magnetism pattern using a clock signal having the same frequency as the pattern generator circuit 15.

0017As shown in <figref idref="f0001">Fig. 1</figref>, the load circuit 9 that receives power from the battery 7 through the semiconductor switch 17 includes an illumination unit 21, an image pickup unit 22 for imaging the inside of the body cavity illuminated by the illumination unit 21, a signal processor and controller circuit 23 for driving and controlling the illumination unit 21 and the image pickup unit 22, and for processing an output signal from the image pickup unit 22, and a wireless circuit 24 for wirelessly and outwardly transmitting image information processed signal. These elements are powered from the semiconductor switch 17 in operation.

0018The external recording device 4 receives the image information wirelessly transmitted by the capsule type medical device 2. The external recording device 4 includes a wireless circuit 25 for receiving a radio wave signal transmitted by the wireless circuit 24 in the capsule type medical device 2 and demodulating the received signal into an image signal, a signal processor and controller circuit 26 for performing image processing on demodulated image information for recording, signal processing for converting the image information into a video signal to be displayed, and control operation, a recording unit 27 for recording the image information, a display unit 28 for displaying the image, and an operation unit 29, such as a keyboard, for sending a control signal to the capsule type medical device 2.

0019<figref idref="f0002">Fig. 2</figref> illustrates the internal structure of the capsule type medical device 2. The capsule type medical device 2 includes an illumination and image pickup window 31 which is a semi-spherical transparent section at one end of the capsule container 6. The capsule type medical device 2 also includes a lens barrel 33 supporting an objective lens 32 that focuses an image at the focus position. The objective lens 32 is arranged inside of the illumination and image pickup window 31 in the center thereof. An image pickup board 34 is arranged so that an image pickup unit 22 thereof is located at the focus position.

0020An illumination board 35 having an illumination unit 21 is arranged around the lens barrel 33 to illuminate an imaging area within which the image pickup unit 22 captures images.

0021A signal processor and controller board 36 bearing the signal processor and controller circuit 26 for performing signal processing and control is arranged next to the image pickup board 34. A wireless board 37 bearing the wireless circuit 24 is arranged adjacent to the signal processor and controller board 36. An antenna 38 is connected to the wireless board 37.

0022A flexible printed board 39 electrically interconnects the illumination board 35, the image pickup board 34, the signal processor and controller board 36 and the wireless board 37. The flexible printed board 39 is bent on its way to the battery 7 to be connected to the positive electrode of the battery 7. The flexible printed board 39 further extends backward so that the end portion thereof is connected to the power switch circuit 8 which is in turn connected to the negative electrode of the battery 7.

0023The magnetic sensor 11 is mounted at the center of a switch board 40 bearing the power switch circuit 8.

0024<figref idref="f0003">Fig. 3</figref> illustrates the structure of the power switch circuit 8. In the power switch circuit 8, the switch driver circuit 16 includes a resistor R, and two N-channel field effect transistors (hereinafter referred to as FETs) 16a and 16b. These elements form a NOR circuit, which on/off controls the semiconductor switch 17 including a P-channel FET 17a. When the magnetic sensor 11 (more specifically a reed switch 11a) is affected by the control of a physical quantity of magnetism, a binary voltage is caused at the node of the resistor R and the magnetic sensor 11. The pattern of the voltage is monitored by the pattern monitoring circuit 18.

0025The reed switch 11a is constructed of a glass tube in which magnetized reed contacts connected to lead wires are encapsulated. The reed switch 11a makes the connection in an on state in response to the application of a magnetic field to the center of the glass tube, and breaks the connection in an off state in response to the removal of the magnetic field. The reed switch 11a thus makes or breaks the connection in a non-contact manner. The response speed of the reed switch 11a is as high as about 500 Hz.

0026The structure of the power switch circuit 8 of <figref idref="f0003">Fig. 3</figref> will now be specifically discussed. The positive electrode of the battery 7 is connected to the gate of FET 16a (first switch drive circuit as one of the two switch drive circuits) forming the switch driver circuit 16 via the magnetic sensor 11 (specifically, the reed switch 11a). The positive electrode of the battery 7 is also connected to a positive power input terminal of the load circuit 9 through the source and drain of FET 17a forming the semiconductor switch 17 and the output terminal of the power switch circuit 8.

0027The gate of FET 16a forming the first switch drive circuit is grounded through the resistor R, while being connected to the input terminal of the pattern monitoring circuit 18 that monitors the on and off pattern signal caused in response to the detection of magnetism of the reed switch 11a.

0028The drain of the FET 16a is connected to the gate of the FET 17a while being connected to the drain of FET 16b forming a second switch drive circuit. The sources of the two FETs 16a and 16b are connected to ground to which the negative electrode of the battery 7 is also connected.

0029The gate of FET 16b is connected to the output terminal of the pattern monitoring circuit 18. The pattern monitoring circuit 18 stores information of a predetermined pattern for switching from an off state to an on state in the same manner as the pattern signal generated by the pattern generator circuit 15 of the remote controller 3. The pattern monitoring circuit 18 determines whether the predetermined pattern matches a pattern of magnetism detected by the reed switch 11a. Depending on the determination result, the pattern monitoring circuit 18 causes the FET 16b to turn on, thereby turning on the semiconductor switch 17.

0030Alternatively, the gate of the FET 17a in the power switch circuit 8 may be connected to the positive electrode of the battery 7 via a high-resistance resistor so that the FET 17a is reliably non-conductive with FETs 16a and 16b turned off.

0031When a magnetic field is applied to the reed switch 11a in the capsule type medical device 2 in response to the operation of the remote controller 3, the reed switch 11a in the power switch circuit 8 is turned on in response to the detection of the magnetic field, thereby causing FET 16a to be turned on. With FET 16a turned on, the gate of the semiconductor switch 17 is driven low in level, and the semiconductor switch 17 is turned on. Power for operation is supplied to the pattern monitoring circuit 18, and the pattern monitoring circuit 18 starts performing a determination operation of the pattern signal.

0032Upon receiving power at first level 1 of the pattern signal, the pattern monitoring circuit 18 is supplied with power and is shifted into an operation state. The pattern monitoring circuit 18 starts a pattern monitoring operation with a slight delay from the transition of the pattern signal to a level 1. However, the pattern monitoring circuit 18 is not affected by the delay because the signal (at a level during level 0 period or level 1 period) is sampled at the same frequency and at a slightly delayed timing to perform the monitoring operation of determining whether the pattern matches the predetermined pattern.

0033The pattern monitoring circuit 18 determines whether the predetermined pattern matches the high and low gate level pattern of FET 16a in response to the on state and the off state respectively detected and undetected by the reed switch 11a.

0034If the pattern monitoring circuit 18 determines that the predetermined pattern matches an on pattern from an off state to an on state, the pattern monitoring circuit 18 outputs a high level signal from the output terminal thereof to the gate of FET 16b, thereby causing the semiconductor switch 17 to transition from off to on.

0035In accordance with the first embodiment, the remote controller 3 is used to cause the power switch circuit 8 to be transitioned from off to on. To transition the power switch circuit 8 from on to off, the external recording device 4 issues a command using wireless communication.

0036The operation unit 29 in the external recording device 4 is operated to transmit, from the wireless circuit 25 to the capsule type medical device 2, a control signal for causing the power switch circuit 8 to turn off. Upon receiving the control signal to turn off, the signal processor and controller circuit 23 in the capsule type medical device 2 transfers the control signal to the pattern monitoring circuit 18. The pattern monitoring circuit 18 turns FET 16b of the switch driver circuit 16 off, thereby turning off the semiconductor switch 17.

0037The operation of the power switch circuit 8 will now be discussed with reference to time charts illustrated in <figref idref="f0004">Figs. 4A-4I</figref>.

0038<figref idref="f0004">Figs. 4A-4I</figref> illustrate operation timings wherein, with power off, the remote controller 3 applies a magnetic field of a magnetism pattern for an on pattern to switch on the power of the capsule type medical device 2, and another magnetic field of another magnetism pattern.

0039As shown in <figref idref="f0004">Fig. 4A</figref>, on bit pattern 110100... is set to switch on power. This on pattern information is also stored in the pattern monitoring circuit 18.

0040When the switch 14 in the remote controller 3 is operated, the pattern generator circuit 15 supplies the electromagnet 12 with pulse current in accordance with the on pattern. A magnetic field of a time series magnetism pattern is caused in response to the presence or absence of the pulse current.

0041The magnetism pattern has a frequency as high as about 400 Hz, and is thus within the response frequency of the reed switch 11a (commercially available reed switches have typically a response frequency of 500 Hz or so).

0042The magnetism pattern applied to the reed switch 11a is illustrated in <figref idref="f0004">Fig. 4B</figref> (with a high level in response to the presence of magnetism and a low level in response to the absence of magnetism). The reed switch 11a is turned on and off in response to the magnetism pattern.

0043In response to the on and off operation of the reed switch 11a, FET 16a is turned on and off, thereby changing the level at the output terminal thereof in response to the magnetism pattern as shown in <figref idref="f0004">Fig. 4C</figref>. As shown, the magnetism pattern is represented by crossing lines.

0044At the timing the reed switch 11a is turned on first, FET 16a is turned on. In response, the semiconductor switch 17 is turned on, thereby supplying power to the pattern monitoring circuit 18. The pattern monitoring circuit 18 then maintains the gate of FET 16b at a high level to keep the semiconductor switch 17 conductive for a duration of time Ta slightly longer than a short period of time required for pattern determination (see <figref idref="f0004">Fig. 4D</figref>). Regardless of the on and off operation of FET 16a, the pattern monitoring circuit 18 performs the pattern determination operation.

0045With the gate of FET 16b maintained at a high level, the semiconductor switch 17 is kept to be on, and the pattern monitoring circuit 18 monitors the pattern. The pattern monitoring circuit 18 determines whether the detected pattern matches the predetermined pattern. The pattern matching determination is completed prior to the end of the duration of time Ta.

0046If the detected pattern is determined to match the predetermined pattern, the pattern monitoring circuit 18 outputs a determination output signal of high level to the gate of FET 16b. The semiconductor switch 17 is kept to be on (see <figref idref="f0004">Fig. 4E). Fig. 4E</figref> shows timing "t" at which the pattern monitoring circuit 18 outputs the determination output signal determining that the detected pattern matches the predetermined pattern. The timing "t" appears prior to the end of time Ta.

0047If a magnetism pattern having a pattern different from the on pattern is applied as shown in <figref idref="f0004">Fig. 4F</figref>, the semiconductor switch 17 is turned on (see <figref idref="f0004">Fig. 4I</figref>) after FET 16a is first turned on. The pattern monitoring circuit 18 causes FET 16b to continuously turn on for the duration of time Ta to monitor the voltage pattern at the gate of FET 16a. FET 16a is turned on and off in response to the magnetism pattern. As in <figref idref="f0004">Fig. 4C</figref>, the magnetism pattern is represented by crossing lines in <figref idref="f0004">Fig. 4G</figref>.

0048Upon determining that the detected pattern fails to match the predetermined pattern, the pattern monitoring circuit 18 outputs a low-level determination signal to the gate of FET 16b. The timing of outputting the low-level determination signal is prior to the end of the duration of time Ta. At this timing, FET 16b is turned off, causing the semiconductor switch 17 to turn off.

0049In the case of the applied magnetism pattern shown in <figref idref="f0004">Fig. 4F</figref>, the timing of determination that the detected pattern fails to match the predetermined pattern comes prior to the timing of determination that the detected pattern matches the predetermined pattern. The timing of determination that the detected pattern fails to match the predetermined pattern varies depending on the magnetism pattern.

0050In accordance with the first embodiment of the present invention, the capsule type medical device 2 is switched on only when the magnetism pattern matching the predetermined magnetism pattern is applied. This arrangement reliably prevents the power of the capsule type medical device 2 from being erratically transitioned from off to on in response to different magnetism pattern. Furthermore, this arrangement prevents the capsule type medical device 2 from being erratically switched on in response to noise, thereby heightening reliability of the medical system.

0051Once the capsule type medical device 2 is switched on, the on state is maintained without the need for continuous application of the magnetism pattern.

0052The first embodiment of the present invention provides the advantages mentioned as below.

0053The power of the capsule type medical device 2 is switched on in response to the application of only the particular magnetism pattern generated by the dedicated remote controller 3. An erratic operation such as an inadvertent switch-on is prevented, and the reliability of the medical system is heightened. The ease of use is assured because the power of the capsule type medical device 2 is switched on by simply applying magnetism of the predetermined pattern temporarily.

0054Since it is sufficient if the magnetic sensor 11 detects the presence of magnetism, the switch-on operation is relatively free from sensitivity of detection. The medical system 1 thus enjoys the reliable detection feature of magnetism while providing robustness against disturbance.

0055In accordance with the first embodiment of the present invention, the power switch circuit 8 determines the presence or absence of magnetism having the particular pattern with almost no power supplied. In other words, when magnetism is not applied, the power switch circuit 8 consumes almost no power.

0056In the previous discussion, the particular magnetism pattern is used to shift the power of the capsule type medical device 2 from an off state to an on state. The present invention is applicable to the shifting of power from an on state to an off state.

0057The sensing characteristics of the magnetic sensor 11 is subject to the direction of magnetization thereof, therefore, the direction of an applied magnetic field.

0058This effect is controlled if a relative direction between the location of the magnetic sensor 11 and the electromagnet 12 of the remote controller 3 is restricted.

0059A second embodiment of the present invention will now be discussed with reference to <figref idref="f0005">Fig. 5</figref>.

0060<figref idref="f0005">Fig. 5</figref> illustrates a medical system 41 of the second embodiment of the present invention. In the second embodiment, the medical system 41 includes light emitting means instead of the magnetism generating means and an optical sensor instead of the magnetic sensor 11 in the first embodiment.

0061The medical system 41 of <figref idref="f0005">Fig. 5</figref> includes a capsule type medical device 2B and a remote controller 3B.

0062The remote controller 3B employs a light emitting device 42 instead of the electromagnet 12 of <figref idref="f0001">Fig. 1</figref>.

0063The capsule type medical device 2B includes the optical sensor 43, such as a photodiode, instead of the magnetic sensor 11. The optical sensor 43 forms a power switch circuit 8B.

0064The power switch circuit 8B includes a photodiode or a phototransistor instead of the reed switch 11a of <figref idref="f0003">Fig. 3</figref>.

0065In accordance with the second embodiment of the present invention, the power switch circuit 8B, including the photodiode or the phototransistor as the optical sensor 43, is integrated into a one-chip module, thereby permitting miniaturized, light-weight and low-cost design. The rest of the structure remains unchanged from the first embodiment of the present invention. The second embodiment of the present invention is almost identical in operation to the first embodiment of the present invention except that light is used instead of magnetism.

0066The second embodiment of the present invention permits miniaturized and low-cost design in addition to the advantages of the second embodiment of the present invention. In the case of magnetism, the detection of magnetism is subject to directionality depending on the direction of magnetization of the magnetic sensor. In contrast, the optical sensor 43 reliably switches on or off the power switch circuit 8B by irradiating the capsule type medical device 2 with light or by stopping light irradiation.

0067A third embodiment of the present invention will now be discussed with reference to <figref idref="f0007">Figs. 7A-7I</figref>.

0068<figref idref="f0006">Fig. 6</figref> illustrates a medical system 41C of the third embodiment of the present invention. In the third embodiment of the present invention, a remote controller 3C is able to shift the power of a power switch circuit 8 from an off state to an on state, and from an on state to an off state in addition to the arrangement of the second embodiment of the present invention. The on pattern to switch on the power and the off pattern to switch off the power are set to be different to reliably switch on and off the power of the capsule type medical device 2.

0069As shown in <figref idref="f0006">Fig. 6</figref>, the medical system 41C includes a capsule type medical device 2C and a remote controller 3C.

0070The capsule type medical device 2C further includes a pattern storage circuit 51 and a pattern reading circuit 52 in addition to the power switch circuit 8B in the capsule type medical device 2B of <figref idref="f0005">Fig. 5</figref>.

0071As shown in <figref idref="f0006">Fig. 6</figref>, the power switch circuit 8C includes the following elements in addition to the power switch circuit 8B. More specifically, in addition to the power switch circuit 8B, the power switch circuit 8C further includes a pattern storage circuit 51 that stores information of an on pattern and an off pattern, and a pattern reading circuit 52 that reads the information of the on pattern and the off pattern from the pattern storage circuit 51 and outputs the information to the pattern monitoring circuit 18.

0072The remote controller 3C includes a pattern storage circuit 54 that stores information of an on pattern and an off pattern, a pattern reading circuit 55 that reads the information of the on pattern and the off pattern from the pattern storage circuit 54, and causes the light emitting device 42 to emit light in the form of pulse, an on switch 14a and an off switch 14b issuing read signals to the pattern reading circuit 55 to read the on pattern and the off pattern, respectively, and a battery (not shown) for feeding power to the pattern storage circuit 54, the pattern reading circuit 55, etc.

0073The pattern storage circuit 54 and the pattern reading circuit 55 in the remote controller 3C may be constructed of a microcomputer with a memory, and the pattern storage circuit 51, the pattern reading circuit 52, and the pattern monitoring circuit 18 in the capsule type medical device 2C may be constructed of a microcomputer with a memory.

0074The operation of the third embodiment of the present invention will now be discussed.

0075To put the capsule type medical device 2C into operation, the on switch 14a of the remote controller 3C is operated.

0076By operating the on switch 14a with the light emitting device 42 aligned with the optical sensor 43, the pattern reading circuit 55 is instructed to read the on pattern. The pattern reading circuit 55 reads the on pattern information from the pattern storage circuit 54, thereby causing the light emitting device 42 to emit light in response to the read information.

0077The on pattern may be the same one as indicated in <figref idref="f0004">Fig. 4A</figref>. The light emitting device 42 emits light at the level 1 and extinguishes at the level 0. A phototransistor as the optical sensor 43 is connected at the location of the reed switch 11a of <figref idref="f0003">Fig. 3</figref>, for example. When light is received, the phototransistor is turned on. In the same manner as the reed switch 11a, the semiconductor switch 17 is turned on, putting the pattern monitoring circuit 18 into operation.

0078As previously discussed, the semiconductor switch 17 is turned on for the pattern monitoring period (with FET 16b of <figref idref="f0003">Fig. 3</figref> turned on).

0079The pattern monitoring circuit 18 reads the on pattern information from the pattern storage circuit 51 via the pattern reading circuit 52, and stores the on pattern information in a register of the pattern monitoring circuit 18, for example.

0080Since the optical sensor 43 (phototransistor) is turned on and off in response to a light emitting pattern of the light emitting device 42, the pattern monitoring circuit 18C determines whether the detected voltage pattern matches on pattern information stored in the register.

0081If the light pattern is substituted for the magnetism pattern of <figref idref="f0004">Fig. 4B</figref>, the operation of the capsule type medical device 2C also follows the pattern of <figref idref="f0004">Fig. 4B</figref>. When the on switch 14a in the remote controller 3C is operated, the pattern monitoring circuit 18C determines the detected voltage pattern matches the on pattern stored in the register, thereby turning the semiconductor switch 17 on.

0082Even if light of a pattern other than the on pattern is directed to the optical sensor 43, the semiconductor switch 17 is prevented from being turned on. If the capsule type medical device 2C is turned on, the illumination unit 21 emits light once or twice a second, and the image pickup unit 22 captures image in synchronization with the light emitting. The captured image signal is signal processed into image information by the signal processor and controller circuit 23. The image information is then wirelessly transmitted outwardly from the wireless circuit 24.

0083After the external recording device 4 verifies the operation of the capsule type medical device 2C, a patient may swallow the capsule type medical device 2C. Subsequent to the verification of the operation, the power of the capsule type medical device 2C may be turned off without being swallowed immediately.

0084To switch off the power of the capsule type medical device 2C, the off switch 14b of the remote controller 3C is turned on.

0085By operating the off switch 14b with the light emitting device 42 facing the optical sensor 43, a command to read an off pattern is issued to the pattern reading circuit 55. The pattern reading circuit 55 reads information of the off pattern from the pattern storage circuit 54, and causes the light emitting device 42 to emit light in accordance with the off pattern information.

0086For example, in response to the off pattern like the one shown in <figref idref="f0007">Fig. 7A</figref>, the light emitting device 42 emits light at level 1 and extinguishes at level 0 as shown in <figref idref="f0007">Fig. 7B</figref>.

0087If a phototransistor as the optical sensor 43 is connected instead of the reed switch 11a of <figref idref="f0003">Fig. 3</figref>, the phototransistor is turned on in response to received light, and turned off when the light emitting device 42 extinguishes. FET 16a is also turned on and off in response to the on and off operation of the phototransistor, as illustrated by crossing lines in <figref idref="f0007">Fig. 7C</figref>.

0088When FET 16a is turned on, the pattern monitoring circuit 18C starts a pattern signal determination process. The pattern monitoring circuit 18C keeps FET 16b conductive in an on state for a constant duration of time Ta (see <figref idref="f0007">Fig. 7D</figref>), and thus keeps the semiconductor switch 17 in an on state for the duration of time Ta.

0089The pattern monitoring circuit 18C reads the off pattern information from the pattern storage circuit 51 via the pattern reading circuit 52, and then stores the read off pattern information in a register or the like therein.

0090The optical sensor 43 (phototransistor) is turned on and off in response to the emission pattern of the light emitting device 42. The pattern monitoring circuit 18 determines whether the detected voltage pattern matches the off pattern information stored in the register or the like.

0091If the pattern monitoring circuit 18C determines that the detected voltage pattern matches the off pattern information stored in the register or the like, the semiconductor switch 17 is shifted from an on state to an off state as shown in <figref idref="f0007">Fig. 7E</figref>.

0092If the light emitting device 42 emits light in an emission pattern different from the off pattern (see <figref idref="f0007">Fig. 7F</figref>), FET 16a is turned on and off in accordance with that emission pattern (see <figref idref="f0007">Fig. 7G</figref>).

0093When FET 16a is turned on, the pattern monitoring circuit 18C starts a pattern signal determination process. The pattern monitoring circuit 18C keeps FET 16b conductive in an on state for a constant duration of time Ta (see <figref idref="f0007">Fig. 7H</figref>), and thus keeps the semiconductor switch 17 in an on state for the duration of time Ta.

0094If the pattern monitoring circuit 18C determines that the detected voltage pattern fails to match the off pattern, the pattern monitoring circuit 18C issues a non-coincidence determination signal to FET 16b to keep FET 16b and thus the semiconductor switch 17 conductive in an on state (see Fig. 71).

0095In accordance with the third embodiment of the present invention, the capsule type medical device 2C is shifted from an off state to an on state or from an on state to an off state. The capsule type medical device 2C is reliably controlled for an off-to-on operation and an on-to-off operation.

0096By setting the on pattern different from the off pattern, the capsule type medical device 2C is more reliably switched on or off.

0097If a plurality of capsule type medical devices 2C are simultaneously used, erratic switching operations are easily prevented by modifying patterns stored in the pattern storage circuits 51 and 54. Depending on applications, the on pattern and the off pattern may be modified.

0098The pattern storage circuit 54 may be designed so that the stored pattern can be easily rewritten. For example, a point of contact for rewriting may be arranged. An external device (not shown) may be connected to the point of contact to rewrite the content of the pattern storage circuit 54 which may be EEPROM or flash memory as an electrically rewritable non-volatile memory.

0099The external recording device 4 may wirelessly transmit the pattern signal to the capsule type medical device 2C. The signal processor and controller circuit 23 forming the load circuit 9 may rewrite the pattern signal stored in the pattern storage circuit 51, which is constructed of an electrically rewritable non-volatile memory.

0100In the foregoing discussion, the pattern monitoring circuit 18C remains on while the semiconductor switch 17 is in an on state. Alternatively, the pattern monitoring circuit 18 may be shifted to an off state by the signal processor and controller circuit 23.

0101Information that the pattern monitoring circuit 18C has shifted the semiconductor switch 17 from an off state to an on state (or from an on state to an off state) may be stored in the pattern monitoring circuit 18C or the pattern storage circuit 51 containing an electrically rewritable non-volatile memory such as EEPROM. In response to the presence or absence of that information, the pattern reading circuit 52 may read the on pattern information or the off pattern information from the pattern storage circuit 51.

0102For example, when the pattern monitoring circuit 18C becomes operational with light input to the optical sensor 43, the pattern monitoring circuit 18C reads the on pattern if off-to-on shifting information is not stored, and determines whether the detected pattern matches the on pattern. If the off-to-on shifting information is stored, the pattern monitoring circuit 18C reads the off pattern and determines whether the detected pattern matches the off pattern.

0103The medical device examines the body by picking up images of internal organs in the preceding embodiments. The present invention is applicable to a medical device that performs medical treatment on an affected part or disperses drugs on an affected part.

0104In the foregoing discussion, the power of the capsule type medical device is switched on and off using any of light, magnetism, and radio waves. The switching control may be performed together with power feeding and position control of the capsule type medical device using any of light, magnetism, and radio waves.

0105A combination of the preceding embodiments in whole or in part falls within the scope of the present invention.

0106In this invention, it is apparent that working modes different in a wide range can be formed on this basis of this invention without departing from the scope of the invention as defined in the appended set of claims.