KR102046788B1 - Apparatus and method for tracking position of capsule endoscope - Google Patents

Abstract

The present invention relates to a capsule endoscope position detection system capable of detecting the position of a capsule endoscope in real time while preventing an extracorporeal device from being detached from a body and a method thereof. The system for detecting the position of a capsule endoscope inserted into a body comprises: a sensor pad having a plurality of sensors formed thereon and disposed on the body surface of a testee to detect ultrasonic signals generated from a capsule endoscope; and an extracorporeal device detecting the position of the capsule endoscope based on the time difference of the ultrasonic signals detected from the sensor pad.

Description

Capsule endoscope position detection system and its method {APPARATUS AND METHOD FOR TRACKING POSITION OF CAPSULE ENDOSCOPE}

The present invention relates to a capsule endoscope position detection system and method, and more particularly, to an ultrasonic signal based capsule endoscope position detection system and method having one sensor attachment point.

The capsule endoscope is a device that is equipped with an image sensor, an image processing device, a wireless data transmission device, etc. in a capsule type device, and acquires an image of the patient's organ and transmits it to a terminal outside the body. It is a device used to diagnose the small intestine.

The capsule endoscope should be manufactured in a very small size to minimize the human impact. Therefore, the small battery capacity causes a short driving time, and thus, when a delay occurs in the digestive organs, the capsule endoscope cannot perform all the necessary diagnostics and discharges the battery. Therefore, there is a need for a technology that can identify the location of the capsule endoscope in the digestive organs in real time so that the medical staff can take action.

 In addition, since the location taken by the capsule endoscope is located in the digestive tract, which is essential information for future diagnosis and treatment, the capsule is required for the operation of matching the captured image with the location in the digestive tract. There is a need for a technique for locating the endoscope in real time.

On the other hand, in the case of currently available capsule endoscope, using six in vitro sensors as shown in Figure 1, attached to the left, middle, right of the upper abdomen, each of the six left, middle, right of the lower abdomen, each in vitro sensor We use a technique to determine the location of the body based on the magnitude of the signal obtained from. Since this method uses six sensors, if any one of the sensors is in contact with the body due to the user's movement, the accuracy drops sharply.

In addition, the capsule endoscope needs to be measured for a long time (10 hours), and the patient must move continuously to stimulate the movement of the digestive organs, so that the sensor body is detached from the body frequently, which causes inaccurate location information.

Accordingly, there is a demand for a technology that can grasp the position of the capsule endoscope in real time while preventing the detachment of the extracorporeal sensor.

Related prior arts include Korean Patent Application Publication No. 10-2018-0075364 (name of the invention: a method and apparatus for position measurement of a wireless endoscope using ultrasonic waves, publication date: July 04, 2018).

The problem to be solved by the present invention is to provide a capsule endoscope position detection system and method that can detect the position of the capsule endoscope in real time while preventing detachment of the body attachment of the extracorporeal sensor.

The problem to be solved by the present invention is not limited to the problem (s) mentioned above, and other object (s) not mentioned will be clearly understood by those skilled in the art from the following description.

Capsule endoscope position detection system according to an embodiment of the present invention, in the system for detecting the position of the capsule endoscope inserted into the body, a plurality of sensors are formed, disposed on the body surface of the subject is generated in the capsule endoscope One sensor pad for detecting the ultrasonic signal, and an extracorporeal device for detecting the position of the capsule endoscope based on the time difference of the ultrasonic signal detected by the sensor pad.

Preferably, the sensor pad, five sensors are formed on one side in the cross shape, each sensor can detect the ultrasonic signal, respectively.

Preferably, the extracorporeal device comprises: a plurality of amplifiers for amplifying the ultrasonic signals detected by each of the plurality of sensors, a plurality of time measuring instruments each measuring a time difference between the arrival time of each amplified ultrasonic signal and the reference time; And a controller for detecting the position of the capsule endoscope based on the time difference measured by each of the plurality of time measuring instruments. The amplifier and the time measuring instrument may be provided for each sensor provided in the sensor pad.

Preferably, the apparatus may further include a reference time generator for generating the reference time.

Preferably, in order to synchronize the time with the capsule endoscope, the output of the time meter may be monitored, and may further include a frequency detector for adjusting the reference time when a predetermined range or more.

Preferably, the time measuring instrument includes a counter for measuring a time difference between the reference time Start and the ultrasonic signal arrival time, a trigger signal based on the arrival time of the ultrasonic signal, and a delayed ultrasonic signal delaying the arrival time of the ultrasonic signal. A TD (time-to-digital convertor) for outputting a digital code, and adding the output of the Fine TDC to the output of the counter, a summation unit for calculating a time difference between the reference time and the ultrasonic signal arriving at the sensor It may include.

Preferably, the Fine TDC is. It may include a delay line including a plurality of delay unit, a plurality of comparators for comparing the trigger signal based on the arrival time of the ultrasonic signal and the delayed ultrasonic signal delayed the arrival time of the ultrasonic signal in the delay unit, and outputs a digital code. .

Preferably, the apparatus further includes a fine TDC calibration unit configured to output a calibration value for calibrating an output of each fine TDC, wherein the fine TDC calibration unit comprises a first rising edge having a time difference corresponding to one period of the system clock CLK. A clock generator for generating Cstop1 and a second rising edge Cstop2 and a reference time Cstart; and comparing the reference time generated by the clock generator with the first rising edge, and converting the difference into the first digital code. A first fine TDC for outputting, a second fine TDC for comparing the reference time generated by the clock generator with a second rising edge, and outputting a difference thereof as a second digital code, the first digital code and the second digital code The calculation unit may include a summing unit for calculating a difference and outputting the calibration value.

Capsule endoscope position detection method according to another embodiment of the present invention, the plurality of sensors formed on one sensor pad, respectively detecting the ultrasonic signal generated from the capsule endoscope, a plurality of amplifiers are detected in each of the plurality of sensors Amplifying an ultrasonic signal, each time amplifier measuring a time difference between the arrival time of each amplified ultrasonic signal and a reference time,

The controller detecting the position of the capsule endoscope based on the time difference measured in each of the plurality of time meters.

According to the present invention, since one sensor pad having a plurality of sensors is attached to the body surface of the subject, the detachment of the body attachment of the sensor can be prevented, whereby the position information of the capsule endoscope can be accurately measured.

Effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.

1 is a view for explaining the concept of a conventional sensor.
2 is a view for explaining a capsule endoscope position detection system according to an embodiment of the present invention.
3 is an exemplary view for explaining a sensor pad according to an embodiment of the present invention.
4 is a view for explaining the concept of the sensor pad according to an embodiment of the present invention.
5 is a view for explaining the concept of the capsule endoscope position detection system according to an embodiment of the present invention.
6 is a view for explaining the difference between the reach distance according to the capsule endoscope and the in vitro attachment sensor position according to an embodiment of the present invention.
Figure 7 is a block diagram illustrating an extracorporeal device for detecting the position of the capsule endoscope according to an embodiment of the present invention.
8 is a timing diagram of a time meter according to an embodiment of the present invention.
9 is a view for explaining a fine TDC according to an embodiment of the present invention, Figure 10 is a fine TDC timing diagram according to an embodiment of the present invention.
11 is a view for explaining a fine TDC calibration unit according to an embodiment of the present invention.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In describing the drawings, similar reference numerals are used for similar elements.

Terms such as first, second, A, and B may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. The term and / or includes a combination of a plurality of related items or any item of a plurality of related items.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a view for explaining a capsule endoscope position detection system according to an embodiment of the present invention, Figure 3 is an exemplary view for explaining a sensor pad according to an embodiment of the present invention, Figure 4 is an embodiment of the present invention 5 is a view illustrating a concept of a sensor pad according to an example. FIG. 5 is a view illustrating a concept of a capsule endoscope position detection system according to an embodiment of the present invention. FIG. 6 is a view of a capsule endoscope according to an embodiment of the present invention. It is a figure for demonstrating the difference of the reach distance according to the position of an in vitro attachment sensor.

Referring to Figure 2, the capsule endoscope position detection system according to an embodiment of the present invention is a capsule endoscope 100 is introduced into the organ of the subject, such as a patient, the data transmitted from the capsule endoscope 100 inside the subject It includes an extracorporeal device 200 for receiving.

The capsule endoscope 100 is an example of a capsule medical device introduced into an organ of a subject, and has an imaging function and a communication function. Specifically, the capsule endoscope 100 may be configured to take a picture of the digestive tract of the human body (H), and to be swallowed form to transmit the photographed image to the outside using a wireless communication method.

Thus, when the subject swallows the capsule endoscope 100, the capsule endoscope 100 moves over the digestive tract from the esophagus to the anus over approximately eight hours. During the movement, the camera provided in the capsule endoscope 100 photographs the inside of the digestive tract. In this case, the camera provided in the capsule endoscope 100 may include an ultra-precision lens having a viewing angle of about 150 °.

In addition, an ultrasonic signal generator exists in the capsule endoscope, and generates an ultrasonic burst signal (hereinafter, referred to as an “ultrasound signal”) according to a predetermined period T _cap (for example, once per 1 ms). The reason why the capsule endoscope generates the ultrasonic burst signal may be to minimize power consumption due to ultrasonic generation.

Since the capsule endoscope is the same as the prior art, a detailed description thereof will be omitted.

The extracorporeal device 200 has a human body communication function for performing human body communication with the capsule endoscope 100 inside the organ using the subject as a communication medium, and a position detection function for detecting the position of the capsule endoscope 100 inside the subject. Have

The extracorporeal device 200 wirelessly receives and stores an image captured by the capsule endoscope 100, and has one sensor pad 300 connected thereto.

The sensor pad 300 receives image information or an ultrasonic signal from the capsule endoscope 100, and transmits the received image information or the ultrasonic signal to the extracorporeal device 200. Accordingly, the extracorporeal device 200 stores image information received from one sensor pad 300, or detects the position of the capsule endoscope 100 based on the ultrasound signal when an ultrasound signal is received.

In addition, the sensor pad 300 is formed with a plurality of sensors, it is disposed on the body surface of the subject. In the sensor pad 300, five sensors 310a, 310b, 310c, 310d, and 310e may be formed in a cross shape, as shown in FIG. 3. Therefore, the sensor pad 300 is provided with one attachment point (not shown) for attaching to the body surface of the subject on one side, and the sensors 310a, 310b, 310c, 310d, 310e on the other side. That is, since the five sensors 310a, 310b, 310c, 310d, and 310e are closely arranged in a cross shape, only one attachment point can exist, and as a result, one attachment point is shown in FIG. 4. Can be attached to the body surface of the subject. Although five sensors are formed in the sensor pad 300, the number and shape of the sensors disposed on the sensor pad 300 may vary. Hereinafter, a case in which five sensors 310 are formed on the sensor pad 300 will be described for convenience of description.

The sensor pad 300 detects an ultrasonic signal from the capsule endoscope 100 transmitted by using the subject (ie, a human body) as a communication medium, and transmits the detected ultrasonic signal to the external device 200.

The extracorporeal device 200 detects the position of the capsule endoscope 100 based on the time difference of the ultrasonic signal of the capsule endoscope 100 transmitted from the sensor pad 100.

A method of detecting the position of the capsule endoscope 100 by the system configured as described above will be described with reference to FIG. 5.

The capsule endoscope 100 generates and transmits an ultrasonic signal at regular intervals. Then, the first to fifth sensors 310a, 310b, 310c, 310d, and 310e of the sensor pad 300 detect the ultrasonic signals transmitted by the capsule endoscope 100 and transmit them to the external device 200.

Meanwhile, the ultrasonic signal generated by the capsule endoscope 100 arrives at the sensors 310a, 310b, 310c, 310d, and 310e attached to the body and propagated in the body, as shown in FIG. 6. Since the distance varies depending on the position of the sensor and the position of the in vitro sensors 310a, 310b, 310c, 310d, and 310e, the time at which the ultrasonic signal arrives varies for each of the sensors 310a, 310b, 310c, 310d, and 310e. Therefore, when the ultrasonic signal arrives at the sensors 310a, 310b, 310c, 310d, and 310e, the position of the capsule endoscope 100 may be determined. Accordingly, the extracorporeal device 200 detects a difference in arrival time by acquiring the ultrasonic signals reaching the five sensors 310a, 310b, 310c, 310d, and 310e, and uses the detected arrival time difference to capture the capsule endoscope 100 ) Position is detected.

A detailed description of the extracorporeal device 200 will be described with reference to FIG. 7.

7 is a block diagram illustrating an extracorporeal device for detecting a position of a capsule endoscope according to an embodiment of the present invention, and FIG. 8 is a timing diagram of a time meter according to an embodiment of the present invention.

Referring to FIG. 7, the extracorporeal device 200 for detecting the position of the capsule endoscope according to an embodiment of the present invention includes a plurality of amplifiers 210, a plurality of time measuring instruments 220, and a controller 230. In this case, the amplifier 210 and the time meter 220 may be a number corresponding to a sensor formed on one sensor pad. For example, when the first to fifth sensors are formed on the sensor pad, the first amplifier 210a and the first time measuring instrument 220a connected to the first sensor, the second amplifier 210b and the second sensor connected to the second sensor are provided. To the time meter 220b, the third amplifier 210c connected to the third sensor, and the third time meter 220c, the fourth amplifier 210d and the fourth time meter 220d connected to the fourth sensor, and the fifth sensor. And a fifth amplifier 210e and a fifth timer 220e connected thereto.

Each amplifier 210a, 210b, 210c, 210d, 210e amplifies the ultrasonic signal detected by each sensor. That is, since the ultrasonic signal detected by each sensor may be a weak signal, the amplifiers 210a, 210b, 210c, 210d, and 210e amplify the weak ultrasonic signal detected by the sensor.

For example, the first amplifier 210a may amplify the first ultrasonic signal detected by the first sensor, the second amplifier 210b may amplify the second ultrasonic signal detected by the second sensor, and the third amplifier 210c may be amplified. Amplifying the third ultrasonic signal detected by the third sensor, the fourth amplifier 210d amplifies the fourth ultrasonic signal detected by the fourth sensor, and the fifth amplifier 210e receives the fifth ultrasonic signal detected by the fifth sensor. Amplify.

The time measuring unit 220 detects a difference in arrival time of the ultrasonic signal amplified by the amplifier 210. At this time, the time measuring instrument 220 measures the time difference between the reference time and the arrival time of the ultrasonic signal. Here, the ultrasonic signal arrival time may refer to the time of the ultrasonic signal arriving at the sensor.

 For example, the first time measuring instrument 220a measures the first time difference between the reference time and the arrival time of the first ultrasonic signal arriving at the first sensor, and the second time measuring instrument 220b measures the second time arriving at the reference time and the second sensor. The second time difference between the arrival time of the ultrasonic signal is measured, and the third time measuring unit 220c measures the third time difference between the reference time and the arrival time of the third ultrasonic signal arriving at the third sensor, and the fourth time measuring unit 220d is measured. The fourth time difference between the reference time and the fourth ultrasonic signal arrival time arriving at the fourth sensor is measured. The fifth time measuring unit 220e measures the fifth time difference between the reference time and the fifth ultrasonic signal arrival time arriving at the fifth sensor. Measure

In order for the time meter 220 to measure time, a reference time is required. Thus, the extracorporeal device 200 may further include a reference time generator 240.

The reference time generator 240 generates a reference time for time measurement. In this case, the reference time generator 240 may generate the high-speed overall system clock CLK by dividing by N. Here, N may be any natural number.

That is, for time measurement, a reference time is required inside the time meter 220. When the difference between the reference time and the arrival time of the ultrasonic signal arriving at the sensor is obtained, the difference in arrival time between the sensors can be calculated.

For example, if the capsule endoscope generates an ultrasonic signal every 1 ms, the extracorporeal device 200 needs a reference time of 1 ms synchronized with it. In general, the oscillator generates a reference clock using a crystal oscillator and generates the required time with each oscillator. Each oscillator has a different frequency depending on the error range provided by the manufacturer. Therefore, even if the extracorporeal device 200 generates a reference time every 1ms, the time exists in the capsule endoscope with the time and error of 1ms generated through the internal oscillator, and the error gradually accumulates over time, The synchronization fails and the time measurement fails.

To this end, a frequency detector 250 for time synchronization with the capsule endoscope is required inside the time meter 220.

The frequency detector 250 monitors the output of the time measuring instrument 220 for time synchronization with the capsule endoscope to adjust the reference time generated by the reference time generator 240. That is, the frequency detector 250 monitors the outputs of the first to fifth time measuring instruments 220a, 220b, 220c, 220d, and 220e, and when this exceeds a predetermined range, the reference time START of the time measuring instrument 220 is started. Serves to regulate.

For example, suppose that the capsule endoscope actually generates an ultrasonic signal every 1 ms, and the reference time of the time meter 220 is generated every 1.01 ms due to an error. If this case is repeated 50 times (after 50 ms), the reference time of the time measuring instrument 220 is delayed by more than half a period, and thus time detection is not performed. The capsule endoscope moves about 2 to 3 cm per second in the body, and there may be a case in which there is no change in the output of the time meter 220 due to the movement of the capsule endoscope within this time according to an error of the reference time. In this case, since the output of the time meter 220 will continue to decrease due to the error of the reference time, if the output of the time meter 220 decreases by a certain range or more, this error is eliminated by reducing the time interval in which the reference time is generated. can do. On the contrary, when the reference time of the time measuring instrument 220 is generated every 0.99 ms, since the output of the time measuring instrument 220 will continue to increase as time passes, the output of the time measuring instrument 220 will increase over a predetermined range. In this case, this error can be eliminated by increasing the time interval at which the reference time is generated. Since the reference time is usually generated by dividing the high-speed overall system clock (CLK) by N, by adjusting this value of N, the reference time of the capsule endoscope can be synchronized.

On the other hand, since the sensors formed on the sensor pad are arranged in close proximity, a time measuring instrument 220 having a high time resolution, for example, 100 ps or less, is required because the time difference of the ultrasonic signal arriving at the sensor is very small. In addition, since the error between the reference time of the capsule endoscope and the reference time of the time meter 220 may still exist despite the synchronization provided by the frequency detector 250, a time meter 220 for measuring a wide time range is required. .

Accordingly, the time meter 220 includes a counter 222, a fine time-to-digital convertor (TDC) 224, and an adder 226.

The counter 222 measures a time difference between the reference time Start and the arrival time of the ultrasonic signal.

Fine TDC 224 measures the difference between the trigger signal based on the ultrasonic signal arrival time and the ultrasonic signal delay time that delayed the ultrasonic signal arrival time. Detailed description of the Fine TDC 224 will be described with reference to FIG. 9.

As such, the time meter 220 is divided into two parts to measure a wide time range using a counter 222 using a high-speed system clock CLK as a synchronization clock, and the remaining time difference is obtained using a fine TDC 224 having a high resolution. By using the measurement, the time meter 220 can be efficiently implemented. For example, when the frequency of the CLK is 400 MHz, the time resolution that can be measured by the counter 222 may be 2.5 ns. The fine TDC 224 can obtain a time resolution corresponding to a two-inverter delay using an inverter chain and flip-flops, for example, a time resolution of 100 ps.

The adder 226 adds the output of the Fine TDC 224 to the output of the counter 222 to calculate a time difference between the reference time and the ultrasonic signal arriving at the sensor.

The operation of the time meter 220 configured as described above will be described using the timing diagram of FIG. 8. Referring to FIG. 8, there is a time difference between 'A (Counter)' and 'B (Fine TDC)' between the rising edge of the reference time START and the rising edge of the arrival time STOP of the ultrasonic signals S _{1 to 5} . have. Therefore, the time difference between the reference time START and the arrival time STOP of the ultrasonic signals S _{1 to 5} may be a time difference of 'C' which is obtained by adding the output of the Fine TDC 224 to the output of the counter 222.

On the other hand, the time resolution of the Fine TDC (224) is determined by the delay of the inverter, as mentioned above, this delay is generally largely changed by the PVT variation. Therefore a circuit is needed to calibrate this value.

Thus, the extracorporeal device 200 may further include a fine TDC calibration unit 260 for calibrating the output of each fine TDC 224.

Detailed description of the fine TDC calibration unit 260 will be described with reference to FIG. 11.

The controller 230 detects the position of the capsule endoscope based on the time difference measured by each time measuring instrument 220.

The time detected by one sensor does not represent the absolute time it takes for the signal generated by the endoscope to reach the sensor. Therefore, an algorithm that can determine the position of the capsule endoscope through the time difference measured between the five sensors is required.

에서 측정되는 시간을 기준으로 하여

에서 측정되는 시간과의 차이를 통해 센서

와 센서

의 시간 차이를 구한다. 같은 방식으로 시간 측정기(220)는 센서

와 센서

, 센서

와 센서

, 센서

와 센서

의 시간 차이를 구할 수 있다. 이때 연속적으로 측정되는 복수개의 시간차이 정보에 대해서 이동평균을 실시하여 사람의 움직임으로 인해 생기는 시간정보의 변화를 최소화함으로서 정확도를 높일 수 있다. 예를 들어 센서

와 센서

의 시간 차이는 시간 측정기와 이동평균 필터를 통해 출력하는 센서

와 센서

시간 차이 값과 센서

와 센서

시간 차이 값의 뺄셈으로 도출할 수 있다. 예를 들어 센서

와 센서

시간 차이가 100ns이고, 센서

와 센서

시간 차이가 80ns이면 센서

와 센서

시간 차이는 20ns이다.If the difference between the times measured by the total of five time measuring instruments 220 is obtained, the time difference arriving at each sensor may be obtained. sensor

Based on the time measured in

The difference between the time measured in the sensor

With sensor

Find the time difference. In the same way the time meter 220 is a sensor

With sensor

, sensor

With sensor

, sensor

With sensor

The time difference can be found. In this case, the moving average may be performed on a plurality of time difference information that is continuously measured, thereby minimizing the change of time information caused by the movement of a person, thereby increasing accuracy. For example sensors

With sensor

The time difference between the sensor is output through the hour meter and the moving average filter

With sensor

Time Difference Values and Sensors

With sensor

It can be derived by subtracting the time difference value. For example sensors

With sensor

100 ns time difference, sensor

With sensor

If the time difference is 80ns, the sensor

With sensor

The time difference is 20 ns.

,

,

에서 측정되는 시간 차이로 아래 수학식 1과 같은 쌍곡선 식을 유도할 수 있다. By knowing the difference in time of arrival at each sensor, the position of the capsule endoscope can be determined. For example, when deriving the x-coordinate of the capsule endoscope,

,

,

The hyperbolic equation as shown in Equation 1 below can be derived from the time difference measured in.

[Equation 1]

는 센서

과 센서

시간 차이 * 초음파 속력/2,

는 센서

과 센서

간 중심 거리,

=

를 의미할 수 있다.Where d is the center distance between adjacent sensors,

Sensor

And sensors

Time difference * ultrasonic speed / 2,

Sensor

And sensors

Liver center distance,

=

It may mean.

,

,

에서 측정되는 시간 차이로 캡슐내시경 위치의 y좌표를 도출할 수 있다. 캡슐내시경 위치의 z좌표(깊이)를 구하기 위해 아래 수학식 2를 이용할 수 있다. The controller may use the x-coordinate of the capsule endoscope position as the mode of the solution derived from three simultaneous equations created by combining the hyperbolic functions (a), (b), and (c) of Equation 1. In this same way, the controller

,

,

The y-coordinate of the capsule endoscope position can be derived from the time difference measured at. Equation 2 below can be used to obtain the z coordinate (depth) of the capsule endoscope position.

[Equation 2]

과

시간 차이 * 초음파 속력을 의미할 수 있다. Where d is the center distance between adjacent sensors and lnm is the sensor

and

Time Difference * Can mean ultrasonic speed.

을 구할 수 있으며, 도출되는 6개의

값들의 평균으로 캡슐내시경 위치의 z좌표 값을 구할 수 있다.As described above, the solution of Equation 2 (d) through (b) through the time difference information measured by the position x and y coordinate values of the capsule endoscope derived using Equation 1 and a time measuring device.

, You can get 6

The average of the values gives the z-coordinate of the capsule endoscope position.

9 is a view for explaining a fine TDC according to an embodiment of the present invention, Figure 10 is a fine TDC timing diagram according to an embodiment of the present invention.

Referring to FIG. 9, the fine TDC 900 according to an embodiment of the present invention may include a plurality of delay units 910a, 910b,..., 910 _n-1 , hereinafter referred to as '910'. And a plurality of comparators 920a, 920b, ..., 920 _n , hereinafter referred to as '920'.

Each of the delay units 910 receives an input signal and outputs the received input signal by delaying a predetermined time. For example, the plurality of delay units 910 may each have a delay time of 't _d '.

In this case, the first delay unit 910a receives the ultrasonic signal arrival time STOP and outputs a first delayed ultrasonic signal td delayed from the ultrasonic signal arrival time. Similarly, the second delay unit 910b receives the first delayed ultrasound signal and outputs a second delayed ultrasound signal that is td delayed from the first delayed ultrasound signal.

The plurality of comparators 920 respectively receive a trigger signal Trigger based on the delayed ultrasonic signal and the ultrasonic signal arrival time STOP. The plurality of comparators 920 determine output bits according to logic levels of the received delayed ultrasound signal and the trigger signal, respectively. For example, the first comparator 920a receives the ultrasonic signal arrival time and the trigger signal, and determines the first output bit D ₀ according to the logic time of the first ultrasonic signal arrival time and the trigger signal. The second comparator 920b receives the first delayed ultrasound start signal and the trigger signal and determines the second output bit D ₁ according to a logic level of the first delayed ultrasound start signal and the trigger signal.

In this case, the delay unit 910 may be implemented as an inverter, and the comparator 920 may be implemented as flip-flops. Accordingly, the Fine TDC 900 is delayed through each of two input signals, that is, the trigger signal based on the ultrasonic signal arrival time and the delayed ultrasonic n-1 inverters which delayed the ultrasonic signal arrival time, respectively, and are inputted to the n comparators. do. Each of the n comparators compares the rising edge of the delayed ultrasonic signal output by being delayed from each of the inverters with the rising edge of the trigger signal, and outputs the comparison result as a digital code. In this case, the difference between the corresponding input signals may be confirmed by the output digital code.

The operation of the fine TDC 900 configured as described above will be described using the timing diagram of FIG. 10. There is a time difference 'D' between the rising edge of the ultrasonic signal arrival time STOP and the rising edge of the trigger signal Trigger. The time difference of 'D' may be the time measured by the delay line and the comparators.

On the other hand, the time resolution of the Fine TDC (900) is determined by the delay of the inverter, as described above, this delay is generally largely changed by the PVT variation. Therefore, there is a Fine TDC calibration section to calibrate this value.

Therefore, the fine TDC 900 calculates the output value of the scaler 930 and the scaler 930 by using the calibration value received from the fine TDC calibration unit, and calculates the final fine by calculating the final fine with '1'. An adder 940 for outputting a value of the TDC may be further included.

11 is a view for explaining a fine TDC calibration unit according to an embodiment of the present invention.

Referring to FIG. 11, the fine TDC calibration unit 1100 according to an embodiment of the present invention may include a clock generator 1110, a first fine TDC 1120, a second fine TDC 1130, and an adder 1140. It includes.

The clock generator 1110 generates a first rising edge Cstop1, a second rising edge Cstop2, and a reference time Cstart having a time difference corresponding to one period of the high speed system clock CLK.

The first fine TDC 1120 compares the reference time generated by the clock generator 1110 with the first rising edge, and outputs the difference as a first digital code.

The second Fine TDC 1130 compares the reference time with the second rising edge and outputs the difference as a second digital code.

The adder 1140 calculates a difference between the first digital code and the second digital code.

As described above, the fine TDC calibration unit 1110 generates two rising edges Cstop1 and Cstop2 having a time difference corresponding to one period of the CLK by using the high speed system clock CLK, and the reference time Cstart. After converting this to digital code outputted using two Fine TDCs of the same structure, and calculating the difference, the code value corresponding to the difference is the value converted to digital time corresponding to one cycle of CLK. The time corresponding to the resolution obtained is equal to the value divided by the resolution of Fine TDC. For example, if the resolution of the counter is 2.5ns and the resolution of Fine TDC is 100ps, the digital value obtained by the Fine TDC calibration unit 1110 will be 25. If the resolution of Fine TDC is changed to 50ps due to PVT variation, the digital value obtained by Fine TDC calibration will be 50. Therefore, by using this value to scale the fine TDC output value of the internal time meter, accurate time conversion can be performed regardless of PVT variation.

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

100: capsule endoscope
200: extracorporeal device
300: sensor pad

Claims (9)

A system for detecting the position of a capsule endoscope inserted into a body,
A plurality of sensors are formed, one sensor pad disposed on the body surface of the subject to detect the ultrasonic signal generated by the capsule endoscope; And
An extracorporeal device for detecting the position of the capsule endoscope based on the time difference of the ultrasonic signal detected by the sensor pad,
The extracorporeal device
Capsule endoscope position detection system for calculating the time difference of the ultrasonic signal by combining the results obtained by measuring the first time resolution and the second time resolution. The method of claim 1,
The sensor pad,
Five sensors are formed crosswise on one side,
Capsule endoscope position detection system, characterized in that each sensor detects each ultrasonic signal. The method of claim 1,
The extracorporeal device,
A plurality of amplifiers each amplifying the ultrasonic signals detected by each of the plurality of sensors;
A plurality of time measuring devices for measuring a time difference between each of the amplified ultrasound signal arrival times and a reference time; And
A controller for detecting the position of the capsule endoscope based on the time difference measured in each of the plurality of time measuring instruments,
The capsule endoscope position detection system, characterized in that provided for each sensor provided in the sensor pad. The method of claim 3,
Capsule endoscope position detection system further comprising a reference time generator for generating the reference time. The method of claim 4, wherein
The capsule endoscope position detection system, further comprising a frequency detector for monitoring the output of the time meter for adjusting the time with the capsule endoscope, and adjusts the reference time when a predetermined range or more. The method of claim 3,
The time meter,
A counter for measuring a time difference between the reference time (Start) and the arrival time of the ultrasonic signal with the first time resolution; And
A fine time-to-digital convertor (TDC) for comparing a trigger signal based on the arrival time of the ultrasonic signal with the second time resolution and a delayed ultrasonic signal for delaying the arrival of the ultrasonic signal; And
And an adder configured to calculate a time difference between the reference time and the ultrasonic signal arriving at the sensor by adding the output of the fine TDC to the output of the counter. The method of claim 6,
The Fine TDC is.
A delay line including a plurality of delay units; And
And a plurality of comparators configured to compare a trigger signal based on the arrival time of the ultrasound signal with a delayed ultrasound signal in which the delay unit delays the arrival of the ultrasound signal, and output a digital code. The method of claim 6,
Further comprising a fine TDC calibration unit for outputting a calibration value for calibrating the output of each Fine TDC,
The fine TDC calibration unit,
A clock generator configured to generate a first rising edge Cstop1 and a second rising edge Cstop2 having a time difference corresponding to one period of the system clock CLK, and a reference time Cstart;
A first fine TDC comparing the reference time generated by the clock generator with a first rising edge and outputting a difference thereof as a first digital code;
A second fine TDC comparing the reference time generated by the clock generator with a second rising edge and outputting a difference thereof as a second digital code; And
And an adder configured to calculate a difference between the first digital code and the second digital code and output the calibration value as a calibration value. Detecting, by a plurality of sensors formed on one sensor pad, ultrasonic signals generated from the capsule endoscope;
Amplifying the ultrasonic signals detected by each of the plurality of sensors by each of the plurality of amplifiers;
Measuring a time difference between each arrival time of each of the amplified ultrasound signals and a reference time by a plurality of time measuring devices; And
The controller detecting the position of the capsule endoscope based on the time difference measured in each of the plurality of time meters,
The measured time difference is calculated by combining the results measured by the first time resolution and the second time resolution capsule endoscope position detection method.

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