JPH0928661A - Endoscope shape sensing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect settings in a system from being affected by changes in the ambient temperature or by the passage of time and to ensure enhanced accuracy in the detection of the endoscope as inserted by proving the system with an adjusting means for establishing agreement between high-frequency signal frequencies and reference signal frequencies. SOLUTION: A CPU 31 has an altering function 31a for changing the driving frequency setting data for changing the driving frequency settings, and sequentially sends the driving frequency setting data via a PIO 30 to a driving frequency setting data storage in a source coil driving circuit 29. The source coil driving circuit 29 sequentially sets the driving frequencies in response to the received data for the driving of a source coil 16i. A DSP 26 extracts, on the basis of a reference signal, a reference signal frequency component from detected signal data, and determines driving frequency setting data with which the detected data amplitude will be the maximum. The thus-determined driving frequency setting data is forwarded to the CPU 31, a driving frequency setting data is set using the received data, and then an actual operation of sensing the endoscope shape is started.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an endoscope shape detecting device for displaying the shape of an insertion portion of an endoscope inserted into a body cavity or the like.

[0002]

2. Description of the Related Art In recent years, endoscopes have been widely used in the medical and industrial fields. This endoscope, especially if it has a soft insertion part, can be inserted into a bent body cavity to diagnose an organ deep inside the body cavity without incision or to insert a treatment instrument into the channel as necessary. It is possible to carry out therapeutic treatment such as excision of polyps and the like.

In this case, some skill may be required to smoothly insert the insertion portion into the bent body cavity, for example, when examining the lower digestive tract from the anus side.

That is, when the insertion work is being performed, a work such as bending the bending portion provided in the insertion portion in accordance with the bending of the conduit is necessary for smooth insertion. For that purpose, the insertion portion is required. It is convenient to know where in the body cavity the position of the tip of the body is, and the current bending state of the insertion part.

For this reason, for example, the publication number W of the PCT application
In the prior art of O94 / 04938, a coil having three orthogonal three axes fixed at a predetermined position is used to sequentially generate alternating magnetic fields having orthogonal vectors in the space, The voltage across the uniaxial coil generated by being induced by the magnetic field generated by the coils of the three axes is measured by the uniaxial coil existing on the coordinate.
The spatial coordinates of the uniaxial coil were detected based on the measured data.

[0006]

In the above-mentioned prior art, the frequency of the high frequency signal for generating the magnetic field and the frequency of the frequency component extracted by the frequency extraction means match due to changes in the ambient temperature and changes over time. Otherwise, the value of the frequency component will deviate from the value that should be extracted, and the position of the endoscope obtained from this value will not match the actual position, so it will not be possible to accurately detect the insertion state. There was a possibility.

Further, by providing the endoscope with the magnetic field generating means or the magnetic field detecting means, the transmission means for connecting the main body of the apparatus and the endoscope becomes long, and electromagnetic wave noise in the use environment is likely to be superimposed, and the transmission is further promoted. Axial noise due to the signal transmitted through the means may also increase.

Further, due to the influence of noise as described above, the detection signal detected by the magnetic detection means, which is originally a weak signal, fluctuates, and the insertion state of the endoscope may not be accurately detected.

Further, in the prior art, since it takes a long time to detect the insertion state of the endoscope and display it on the display means, it is difficult to follow the actual insertion work, and high-speed processing is desired. .

In view of the above problems, it is an object of the following.

A first object of the present invention is to make the setting of the apparatus less susceptible to changes in ambient temperature and changes over time, and to more accurately detect the insertion state of the endoscope. An object is to provide an endoscope shape detection device.

A second object of the present invention is to drive the alternating magnetic field to be generated in a stable and accurate frequency state, improve the accuracy of the frequency component signal to be extracted, and detect the endoscope shape more accurately. That is.

A third object of the present invention is to be less susceptible to electromagnetic noise in the environment of use and to detect the insertion state of the endoscope more accurately. A fourth object of the present invention is to accurately obtain the position of the endoscope even when an abnormal signal is included in the plurality of detection signals detected by the magnetic field detecting means. A fifth object of the present invention is to improve the detection speed of the insertion state of the endoscope.

[0014]

In order to achieve the first and second objects, in order to detect the insertion shape of the endoscope, a magnetic field is generated which receives a high frequency signal and emits an electromagnetic wave accompanied by a magnetic field. Means, magnetic field detecting means for receiving the electromagnetic wave and detecting magnetic field information of the received electromagnetic wave, and frequency extracting means for extracting a predetermined frequency component from a detection signal detected by the magnetic field detecting means by referring to a reference signal. An insertion state detecting means for detecting an insertion state of the endoscope based on a frequency component signal extracted by the frequency extracting means, a display means for displaying the insertion state detected by the insertion state detecting means, and the magnetic field. A detection signal transmission means for transmitting the detection signal detected by the detection means to the insertion state detection means side; and a high frequency signal transmission means for transmitting a high frequency signal supplied to the magnetic field generation means, In the endoscope shape detecting device in which any one of the field detecting means and the detection signal transmitting means, or the magnetic field generating means and the high frequency signal transmitting means is provided in the insertion portion of the endoscope, the frequency of the high frequency signal and the By providing a frequency adjusting means for matching the frequency of the reference signal, even in an environment where the frequency of the high frequency signal and the frequency of the reference signal deviate from each other due to changes in ambient temperature or changes over time Therefore, the setting of the endoscope shape detecting device is less likely to be affected, and the insertion state of the endoscope can be detected more accurately.

In order to achieve the third object, when a plurality of the magnetic field detecting means are constituted as one set, each of the detection signal transmitting means is provided with a potential of a shield covering portion provided for covering a signal. Shield drive means are provided to keep them equal.

When a plurality of magnetic field detecting means are constituted as one set, the potential of the shield coating portion provided to cover the signal line is kept equal to each of the detection signal transmitting means, so that the shield coating is provided. It is possible to reduce noise superposition and radiation between the parts and between the signal line and the shield coating.

In order to achieve the fourth object, when the insertion state detecting means determines that the position of the endoscope obtained is not a value in a detectable region, position detection is performed to correct the position obtained by a predetermined additional condition. Provide means.

When the obtained position of the endoscope is not the value of the detectable region, the position obtained by the predetermined additional condition is corrected, so that the position of the endoscope can be detected more reliably and accurately. .

In order to achieve the fifth object, among the series of processes performed by the frequency extracting means and the insertion state detecting means,
The processing for generating the display data to be displayed by the display means is executed by the main processing means, the other processing is divided into a plurality of sub-processings, and the respective processings are executed by one or more sub-processing means to obtain the processing result. To the main processing unit.

Of the series of processes performed by the frequency extraction means and the insertion state detection means, the main processing means executes the processing for generating the display data to be displayed on the display means,
Other processes are divided into multiple sub-processes, and each process is divided into 1
Since the processing results are transferred by the main processing means by being executed by one or more sub-processing means, the execution contents of the main processing means or the sub-processing means are simplified and each processing time is shortened. Moreover, since parallel processing can be performed at the same time, the processing time as a whole can be shortened.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIGS. 1 to 14 show a first embodiment of the present invention.
1 shows a configuration of an endoscope system including the first embodiment, and FIG. 2 shows a configuration of an endoscope shape detecting device according to the first embodiment. 3 shows a block diagram of the configuration of the source coil drive circuit unit, FIG. 4 shows the configuration of the frequency oscillating circuit, FIG. 5 shows the specific circuit configuration of the GAIN circuit, and FIG. 6 shows the configuration of the sense coil amplifier circuit. FIG. 7, FIG. 7 shows a specific circuit configuration of the sense coil amplifier circuit, FIG. 8 shows one display example of the display screen, and FIG. 9 shows a plurality of sense coils provided around the bed. Fig. 10 shows how to detect the existence range of two source coils, and Fig. 10 shows the shape of the uniform magnetic field surface by the uniaxial coil.
FIG. 11 shows how the position is corrected from the tilt, and FIG. 12 shows the processing contents of the endoscope shape detection device in a flow chart.
3 shows a graph measured by changing the distance between the values of the maximum magnetic field strength and the minimum magnetic field strength detected by the sense coil at a known distance between the sense coil and the source coil in the shield room, and FIG. 14 shows the data of FIG. An explanatory view of a measuring method and the like for obtaining

An endoscope system 1 shown in FIG. 1 includes an endoscope apparatus 2 for performing an endoscopic examination and an endoscope shape detecting apparatus 3 of the first embodiment used for assisting the endoscopic examination. With and
This endoscope shape detecting device 3 is used for a patient 5 lying on a bed 4.
The insertion portion 7 of the electronic endoscope 6 is inserted into the endoscope and used as an insertion assisting means when performing an endoscopic examination.

In the electronic endoscope 6, an operating portion 8 having a bending operating knob is formed at the rear end of a flexible elongated insertion portion 7, and a universal cord 9 is extended from the operating portion 8. It is connected to a video imaging system (or video processor) 11.

A light guide is inserted into the electronic endoscope 6 to transmit the illumination light from the light source section in the video processor 11 and to emit the transmitted illumination light from the illumination window provided at the tip of the insertion section 7. Illuminate the affected area. An object such as an illuminated affected part is imaged by an objective lens attached to an observation window provided adjacent to the illumination window on an image pickup device arranged at the image forming position, and the image pickup device photoelectrically converts the image.

The signal photoelectrically converted is the video processor 1.
A standard video signal is generated by signal processing by the video signal processing unit in 1 and is displayed on the observation monitor 12 for image observation connected to the video processor 11.

The electronic endoscope 6 has a forceps channel 13
The forceps channel 13 has an insertion opening 13a.
, For example, 16 source coils 16a, 16b, ...
By inserting the probe 15 having 16p (represented by 16i), the source coil 16i is inserted into the insertion portion 7.
Is installed. The source cable 18 extending from the rear end of the probe 15 has a rear end connector removably connected to the device body 21 of the endoscope shape detecting device 3. Then, by applying a high-frequency signal (driving signal) from the device body 21 side to the source coil 16i serving as the magnetic field generating means via the source cable 18 serving as the high-frequency signal transmitting means, the source coil 16i surrounds the electromagnetic wave accompanied by the magnetic field. Radiate to.

In addition, the bed 4 on which the patient 5 lies has four common three centers, each of which is composed of three sense coils 22k wound around three axes orthogonal to each other and constituting magnetic field detecting means for detecting a magnetic field. Axis sense coils 22a-22d
(Represented by 22j) is installed at a predetermined position.
The number of sense coils 22k is 12 in total.

The three-axis sense coil 22j is connected to the connector of the bed 4 by the sense cable 1 as a detection signal transmitting means.
4 (the sense cable connected to each sense coil 22k as shown in FIG. 6 is indicated by reference numeral 19) is connected to the apparatus main body 21. The apparatus main body 21 is provided with an operation panel 35 or a keyboard or the like for the user to operate the apparatus. Further, a monitor 23 as a display means for displaying the detected endoscope shape is connected to the apparatus main body 21.

Further, the detailed structure of the endoscope shape detecting device 3 will be described with reference to FIG. Insertion section 7 of electronic endoscope 6
16 source coils 16i for generating a magnetic field are arranged at a predetermined interval on the probe 15 installed in the probe 15. These source coils 16i are sources for generating 16 different high-frequency drive signals. It is connected to the coil drive circuit unit 29.

Each source coil drive circuit section 29 drives each source coil 16i with a sinusoidal drive signal current having a different frequency, and the respective drive frequencies are the inside of the source coil drive circuit section 29 (the frequency oscillation circuit of FIG. 4). 40)
The drive frequency setting data storage means or the drive frequency setting data (also referred to as drive frequency data) stored in the drive frequency setting data storage means. This drive frequency data is used by a CPU that performs endoscope shape calculation processing and the like.
It is stored by the (central processing unit) 31 via the PIO (parallel input / output circuit) 30 in the drive frequency data storage means (specifically, the latch 40c in FIG. 4) in the frequency oscillation circuit 40.

On the other hand, the sense coil signal amplifier circuit 24k of the sense coil signal amplifier circuit section 24 (see FIG. 6) is provided for each of the twelve sense coils 22k constituting the four sets of three-axis sense coils 22j. Connected to each of the sense coils 22k.
It is amplified to a level that can be read by DC (analog-digital converter) 25k.

1 of this sense coil signal amplifier circuit section 24
The outputs of the two systems are transmitted to 12 ADCs 25k, and a DSP (digital signal processor) 26 that performs frequency extraction processing and position detection processing of the source coil 16i.
It is converted into digital data at a predetermined sampling cycle by a clock supplied from This digital data is read by the DSP 26, and the DSP memory 27
Is written to.

In the DSP 26, the DSP memory 27
A frequency extraction process is performed on the digital data written in, to separate and extract the magnetic field detection information of the frequency component corresponding to the drive frequency of each source coil 16i, and the electronic endoscope is extracted from each digital data of the separated magnetic field detection information. The spatial position coordinates of each source coil 16i provided in the insertion portion 7 of 6 are calculated and stored in the 2-port memory 28. The 2-port memory 28 has a port for exchanging data with the DSP 26 and a port for an address space continuous with the main memory 32 of the CPU 31, and is used as a data exchange buffer between the CPU 31 and the DSP 26.

The CPU 31 estimates the insertion state of the insertion portion 7 of the electronic endoscope 6 from the position coordinate data, generates display data for forming an endoscope shape image, and outputs it to the video RAM 33. The video signal generation circuit 34 reads the data written in the video RAM 33, converts it into an analog video signal, and outputs it to the monitor 23. When the monitor 23 receives the analog video signal, the monitor 23 displays the insertion shape of the insertion portion 7 of the electronic endoscope 6 on the display screen.

In the first embodiment, when the frequency of the high frequency signal for generating the magnetic field is deviated from the frequency of the frequency component extracted by the frequency extracting means due to the change of the ambient temperature or the change over time. To deal with
For example, there is provided a frequency adjusting means for finely adjusting the frequency of the high frequency signal to set the frequency to substantially match the frequency of the frequency component extracted by the frequency extracting means. Before the operation of actually displaying the endoscope shape, the frequency of the high-frequency (driving) signal is changed within a predetermined range, and the frequency of the high-frequency signal is locked so that the detection value of the detection signal becomes maximum. The endoscope shape can be detected and displayed.

Specifically, the CPU 31 shown in FIG. 2 has a drive frequency setting data changing function 31a for changing the set value of the driving frequency so as to sweep it within a predetermined range, and this driving frequency setting data is transmitted via the PIO 30. Sequentially to the drive frequency setting data storage means in the source coil drive circuit unit 29, and the source coil drive circuit unit 29 drives the source coil 16i by sequentially setting the drive frequency according to the drive frequency setting data.

Then, on the DSP 26 side, the detection signal data of the frequency component of the reference signal is extracted based on the reference signal, and the processing for obtaining the drive frequency setting data when the amplitude of the detection signal data is maximum is performed. Then, after the drive frequency setting data is notified to the CPU 31 side and the drive frequency setting data in the source coil drive circuit unit 29 is set or locked to that data, the actual endoscope shape detecting operation is performed. It has a configuration that allows

Next, the operation of this embodiment will be described. First, when the power of the endoscope shape detection device 3 is turned on,
A ROM (not shown) in which the processing program executed by the CPU 31 and the processing executed by the DSP 26 are recorded is booted, and the CPU processing program is transferred to the main memory 32 of the CPU 31. After that, the CPU 31 sequentially performs initialization of peripheral circuits and the like, and transfers the DSP processing program to the DSP memory 27 via the 2-port memory 28. Further, the data for setting the drive frequency of each source coil 16i is transferred via the PIO 30 to the drive frequency setting data storage means or the drive frequency setting data storage means in the source coil drive circuit 29 (specifically, the latch 40 of FIG. 4).
Transfer to c). The source coil drive circuit 29 drives 16 source coils 16i simultaneously based on this drive frequency setting data.

After this predetermined time, the DSP 26 causes the CPU 3
After the peripheral circuit of the DSP 26 is initialized by the processing program transferred from the No. 1, the ADC 25k is controlled and the detection signal of the sense coil is sampled.
The sampling cycle at this time is about 30 KHz, and 1024 pieces of data are converted for each ADC by one sampling. The 12 × 1024 pieces of digital detection data are stored in the DSP memory 27.

The sense coil amplifier circuit section 24 shown in FIG. 2 is provided with an LPF that allows only frequencies lower than 15 kHz to pass therethrough, so that the stored digital detection data contains frequency components of 0 to 15 kHz. For,
By applying FFT (Fast Fourier Transform), which is a frequency component extraction process, all 16 types of frequency components designated in advance in a one-to-one correspondence with the 16 source coils 16i are extracted. The specified frequency is selected from the range of 9 KHz to 11 KHz, which is less attenuated by the human body or metal. This extraction process is performed with 12 sense coils 2
This is all performed on the digital detection data obtained by A / D converting the 2k output, and as a result, all the data including the information regarding the position of the source coil 16i in each sense coil 22k is detected.

At this stage, the CPU 31 and the DSP 26 optimize the drive frequency of the source coil 16i at the time of start-up or when there is a request from the user. This process is performed by adjusting the frequency of the drive frequency and the frequency of the reference signal when extracting the frequency component so that one or both frequencies are affected by the ambient temperature or changes over time, and both frequencies are shifted. Even in an environment in which the S / N ratio is changed, by adjusting one of the frequencies (in the present embodiment, the frequency on the drive frequency side is adjusted), the two frequencies are held in a matched state and the S / N ratio is reduced. It is possible to perform high and highly accurate position detection.

More specifically, the drive frequency setting data changing function 31a of the CPU 31 increments the drive frequency setting data at a predetermined time interval (for example, to cover a frequency within a certain range), and outputs the drive frequency setting data. The amplitude data of the detected signal to be detected is stored in the DSP memory 27,
The drive frequency setting data that maximizes the amplitude data (that is, the detected value) is fed back to the CPU 31 via the 2-port memory 28.

The CPU 31 receives the fed back drive frequency setting data (detection value becomes maximum) from the PIO 30.
To the source coil drive circuit unit 29 (driving frequency setting data storage means) and set (lock) to this driving frequency setting data.

Then, the source coil drive circuit section 29 uses each of the source coil 16 by using the drive frequency setting data.
i will be driven at each optimized frequency. By performing such a drive frequency optimization before use, it is possible to reduce the influence even when there is an influence on the device due to a change in ambient temperature or a change over time, and it is possible to increase the S / N ratio and increase the S / N ratio. Since the detection signal component of sensitivity can be decomposed, highly accurate position detection can be performed.

As a next step, the DSP 26 extracts 16 source coils 16i from all the extracted frequency components.
Is calculated, and the result is transferred to the 2-port memory 28.

Thereafter, the DSP 26 (1) sampling the sense coil detection signal → (2) extracting frequency components →
(3) The position calculation of the source coil is repeated. On the other hand, CP
After completing each initial setting, the U31 waits until the first position coordinate data of each source coil 16i is transferred from the DSP 26 to the 2-port memory 28.

When the CPU 31 recognizes that the first data transfer of the position coordinates by the DSP 26 is completed, the CPU 31
6 data transfer to the 2-port memory 28 is prohibited, and the source coil position coordinate data in the 2-port memory 28 is moved (transferred) to the main memory 32, and the probe 15 is installed based on this transfer data. Electronic endoscope 6
The shape detection process of the insertion part 7 is started. CPU31
When the movement of the source coil position coordinate data to the main memory 32 is completed, the data transfer to the 2-port memory 28 of the DSP 26 is enabled.

Further, when the shape detection processing of the insertion portion 7 of the electronic endoscope 6 is completed, the CPU 31 allocates the insertion shape display data as the processing result to the moving image display portion 35d as shown in FIG. After that, the CPU 31 outputs the display data of the entire screen including the surrounding still image display unit to the video RAM 33.

Thereafter, the CPU 31 (1) moves the source coil position coordinate data to the main memory 32, (2) processes the shape detection position of the insertion portion 7 of the electronic endoscope 6, and (3) displays the inserted shape display data. Allocation → (4) The output of the display data to the video RAM 33 is repeated. The display data of the video RAM 33 is periodically read by the video signal generation circuit 34 and displayed on the monitor 23.

The same effect can be obtained by extracting the frequency component by synchronous detection using the DSP 26 instead of FFT. Also in this case, the source coil 16i
Drive frequency setting data of the CPU 31 is obtained by communication with the CPU 31, a sine reference signal table is calculated based on the drive frequency setting data, and the sine reference signal table is stored in the DSP memory 27. Just create it.

The configuration and operation of each unit will be described more specifically below. FIG. 3 is a block diagram showing the configuration of the source coil drive circuit unit 29. As shown in FIG. 3, the source coil drive circuit unit 29 counts the pulse of the fundamental frequency and
From a frequency oscillating circuit 40 configured to oscillate different frequencies in the range of Hz to 11 KHz, and a plurality of GAIN circuits (or gain circuits) 41 for stabilizing an output signal from the frequency oscillating circuit 40 to a predetermined amplitude. Each of the GAIN circuits 41 is connected to the source coil 16i and drives the source coil 16i.

The GAIN circuit 41 is a frequency oscillating circuit 40.
LPF (low-pass filter) 41a for extracting a sine wave signal which is a fundamental wave of a rectangular wave signal output from
A sine wave signal from F41a is amplified by a predetermined amplification factor, a first stage amplifier 41b, a multiplier 41c that multiplies the output of the first stage amplifier 41b by the signal of the comparison circuit 41e, a current buffer 41d, and a current flowing through the source coil 16i. LPF 41h for removing harmonic components contained in the detected signal
An adjusting amplifier 41g for amplifying the signal from the LPF 41h, a smoothing circuit 41f for smoothing the signal from the adjusting amplifier 41g, and a comparing circuit 41e for comparing the signal of the smoothing circuit 41f with the Ref signal. .

FIG. 4 shows a specific circuit configuration of the frequency oscillating circuit 40. Here, for simplification, the case where eight source coils 16i are driven is shown. That is, the number of GAIN circuits 41 that drive the source coils 16i in the source coil drive circuit unit 29 is also eight.

The frequency oscillating circuit 40 counts the pulses of the fundamental frequency output from a crystal oscillator (not shown).
A program logic circuit (abbreviated as LCA) 40a configured by a program logic element that oscillates eight different frequencies in the range of KHz to 11 KHz, and drive frequency setting data transferred from the CPU 31 via the PIO 30 as a frequency counter number. Latch 40c for storing
And a decoder 40d for selecting the latch 40c transferred by the CPU 31 and an RO for loading the LCA 40a.
It is composed of M40b. The circuit configuration of the LCA 40a can be rewritten (changed) by a program. The high frequency signals of eight frequencies (FRE0 to FRE7 in FIG. 4) output from the LCA 40a are respectively G
It is applied to the high frequency signal input terminal FRE of the AIN circuit 41.

FIG. 5 shows a more specific circuit configuration of the gain circuit 41 of FIG. The high frequency signal input terminal FRE to which the oscillation signal is supplied from the frequency oscillation circuit 40 is a capacitor C1,
Only the oscillation signal of this frequency is transmitted through the LPF 41a including the capacitors C2, C3, C4 and the coils (inductors) L1, L2 via the resistor R1. This signal is the resistance R2
And is input to the differential amplifier U1 (for example, LM6218N) that constitutes the first-stage amplifier 41b.

The non-inverting input terminal of the differential amplifier U1 is grounded, and the inverting input terminal and the output terminal are set by variable resistors R3 and R4 for gain setting. The positive and negative power supply terminals are connected to the positive and negative power supplies + 15V and -15V, respectively, and are grounded via oscillation preventing capacitors C5 and C6.

The signal amplified by the differential amplifier U1 is used as an integrated circuit (IC) U2 (for example, A
D633JN) to one input terminal. The other input end to which the output signal of the comparison circuit 41e is applied is a resistor R5.
Grounded. The positive and negative power supply terminals of this ICU2 are connected to the positive and negative power supplies + 15V and -15V, respectively, and the capacitors C7 and C8 for preventing oscillation are connected.
Grounded.

The output signal of the ICU 2 is applied to the input end of the ICU 3 which constitutes the current buffer 41d via the resistor R6, is current-amplified, and then is applied to one terminal RCV for driving the source coil 16i via the capacitor C11. Is applied. The positive and negative power supply terminals of this ICU 3 are connected to the positive and negative power supplies + 15V and -15V, respectively, and are grounded via oscillation preventing capacitors C9 and C10.

Terminal C on the return side of the source coil 16i
The OM is grounded via the resistor R7 and the LPF41
It is connected to the input terminal of h. The LPF 41h is composed of capacitors C12, C13, C14 and coils L3, L4.

The output terminal of the LPF 41h is connected to the inverting input terminal of the differential amplifier U4 (eg LM6218N) which constitutes the adjusting amplifier 41g via the resistor R8.
The inverting input terminal of the differential amplifier U4 has a gain setting resistor R
It is connected to the output terminal via 9. The non-inverting input terminal is grounded.

The output terminal of the differential amplifier U4 is the smoothing circuit 4
Diode D1 configuring 1f (eg 1S1588)
Of the diode D1 and the cathode of the diode D1 is grounded via a capacitor C15 and a resistor R10, respectively. Further, the cathode serving as the output terminal is a differential amplifier U that constitutes a comparison circuit 41e via a resistor R11.
5 (for example, LM6218N) is connected to the inverting input terminal.

The inverting input terminal of the differential amplifier U5 is connected to its output terminal via the capacitor C16, and the resistor R15 and the capacitor are connected in parallel to the capacitor C16. The non-inverting input terminal is connected to the variable terminal of the variable resistor R13 for setting the reference voltage, and the variable resistor R1
One end of 3 is connected to the positive power supply end via a variable resistor R12, and the other end is connected to GND via a resistor 14.

The positive power supply terminal of the differential amplifier U5 is connected to the positive power supply + 15V, grounded via the oscillation preventing capacitor C18, and the negative power supply terminal is grounded. The output of the differential amplifier U5 is input to the multiplier 41c.

For example, the differential amplifiers U1 and U4 are 1
They are housed in one IC package and the power is commonly supplied. Therefore, the terminal NC of the differential amplifier U4 in FIG.
1, NC2 means no connection. Also, the differential amplifier U5
Is also one of the differential amplifiers housed in one IC package. Next, the operation of the source coil drive circuit unit 29 configured as above will be described. A pulse having a fundamental frequency of a crystal oscillator (not shown) is counted in the LCA 40a and a predetermined frequency is output to the GAIN circuit 41. In the GAIN circuit 41, the LPF 41a extracts a sine wave signal having the frequency of the fundamental wave of the rectangular wave signal from the rectangular wave signal output from the LCA 40a, and outputs this signal to the first stage amplifier 41.
In b, the voltage is amplified to drive the source coil 16i.

In the multiplier 41c, the signal amplified by the first-stage amplifier 41b is multiplied by the signal from the comparison circuit 41e described later to control the gain of the signal from the first-stage amplifier 41b and stabilize the amplitude. Signal is current buffer 41d
The source coil 16i is driven via. The LPF 41h is passed through in order to remove harmonic components contained in the signal for detecting the current flowing through the source coil 16i. LPF41h
The signal from is amplified by the adjustment amplifier 41g, and the smoothing circuit 41f creates a comparison signal to the comparison circuit 41e.

The comparison circuit 41e compares the comparison signal of the smoothing circuit 41f with the Ref signal and outputs it as a feedback signal to the multiplier 41c. The multiplier 41c multiplies this feedback signal by the output of the first stage amplifier 41b. By repeating the above operation, it is possible to always obtain a frequency with a stable amplitude. Here, the Ref signal is set to be equal to the output voltage of the smoothing circuit 41f when the voltage is set to drive the source coil 16i by the first-stage amplifier 41b.

With the above operation, the source coil 16i can be stably driven. Note that one type of crystal oscillator may not be able to obtain the target frequency, and therefore several types of crystal oscillators may be used to obtain the target frequency.

Next, the structure and operation of the sense coil signal amplifier circuit section 24 will be described. The sense coil signal amplification circuit section 24 includes four three-axis sense coils 22.
Although twelve systems of amplifier circuits are provided to connect to the twelve sense coils 22k forming j, the circuit configuration is common to all twelve systems, so the description is simplified and only one system of sense coil signal amplification is performed. The circuit 24k will be described.

As shown in FIG. 6, the sense coil signal amplifying circuit 24k has a twisted pair sense cable 19 covered with a shield 20 for transmitting the signal detected by the sense coil 22k, and a signal from the sense cable 19 having a high input impedance. , A differential input instrumentation amplifier 24a, an HPF (high-pass filter) 24b for attenuating low frequency components included in the output of the instrumentation amplifier 24a, and the HP
LPF for removing high frequency components contained in the output of F24b
24c, an adjustment amplifier 24d that adjusts the overall amplification factor of the sense coil signal amplification circuit 24k to a predetermined value, a level detection circuit 24e that detects the output level of the adjustment amplifier 24d, and a twisted pair of the sense cable 19 A shield drive circuit 24f for adjusting the potential of the shield 20 of the sense cable 19 based on the level of one signal line.

FIG. 7 shows a specific structure of the sense coil signal amplifier circuit 24k. The sense cable 19 connected to the sense coil 22k is connected to the inverting and non-inverting input terminals of the differential amplifier U7 (for example, AD624CP) that constitutes the instrumentation amplifier 24a, and is also connected to GND via the high resistances R21 and R22. Has been done. The offset of the input voltage is adjusted by the variable resistor R23, and the offset of the output voltage is adjusted by the variable resistor R24. The positive and negative power source terminals are grounded via capacitors C21 to C24.

The output terminal of the differential amplifier U7 is HPF24.
The HPF 24b is connected to the input terminal of b and is composed of capacitors C25 and C26 and resistors R25 and R26. The output end of the HPF 24b is connected to the LPF 24c. The output terminal of the LPF 24c is connected via a resistor R27 to the inverting input terminal of a differential amplifier U8 (eg, LM6364N) that constitutes the adjustment amplifier 24d.

This inverting input terminal has a gain adjusting resistor R28.
Is connected to the output terminal via. In addition, the differential amplifier U
The non-inverting input terminal of 8 is connected to GND. The positive and negative power supply terminals are grounded via capacitors C27 and C28. Further, the offset of the differential amplifier U8 is adjusted by the resistor R29. The output terminal of the differential amplifier U8 is connected to the input terminal of the ADC 25k and also to the anode of the diode D2 which constitutes the level detection circuit 24e.

This diode D2 (for example, 1S158
The cathode of 8) is connected to GND via a capacitor C29 and a resistor R30, respectively, and at the same time, differential amplifiers U9 to U12 (for example, LM33) that function as comparators.
9N) and the non-inverting input terminals thereof, respectively. The inverting input terminals of the differential amplifiers U9 to 12 are adapted to be applied with a predetermined voltage obtained by dividing a predetermined power supply voltage (15V in this case) by the resistors R31 to R37. Differential amplifier U9
.About.12 are composed of four differential amplifiers housed in one IC package, the positive and negative power source terminals are connected to the positive power source and GND, respectively, and the positive power source terminal is the capacitor C.
It is grounded through 30.

The output terminals of the differential amplifiers U9 to U12 are connected to + 5V via pull-up resistors R38, respectively. The output terminals of the differential amplifiers U11 and U12 are connected to the input terminal of the second NAND gate N2 via the first NAND gate N1 and to the input terminal of the third NAND gate N3 via the inverters I1 and I2, respectively. Connected. The output terminal of the third NAND gate N3 is connected to the input terminal of the second NAND gate N2, and the output terminal of the second NAND gate N2 is connected to one input terminal of the fourth NAND gate N4.

The output terminal of the differential amplifier U10 is connected to the other input terminal of the fourth NAND gate N4, and the output terminal of the fourth NAND gate N4 is D through the inverter I3.
Connected to SP26. The output terminals of the differential amplifiers U9 and U10 are also connected to the DSP 26.

The differential input GND of the differential amplifier U7
The terminal is a differential amplifier U that constitutes the shield drive circuit 24f.
13 (for example, LM110J) is connected to the non-inverting input terminal. The inverting input terminal of the differential amplifier U13 is connected to the output terminal and applied to the input terminal to current-amplify the signal and output it. Also, the positive and negative power supply terminals are positive power supply +15, respectively.
It is connected to the V and negative power supplies -15V, and the positive and negative power supply ends are grounded via capacitors C31 and C32. Further, the offset of the differential amplifier U13 is adjusted by the resistor R39. The output terminal of the differential amplifier U13 is connected to the shield 20 via the resistor R40.

Next, the operation of the sense coil signal amplification circuit section 24 will be described. A signal obtained by the sense coil 22j detecting the magnetic field generated by the source coil 16i is transmitted by the sense cable 19 and input to the instrumentation amplifier 24a. The instrumentation amplifier 24a amplifies the sense coil detection signal about 200 times and outputs it to the HPF 24b.

The HPF 24b has a cutoff frequency of 1K.
It is a second-order RC filter of Hz and mainly reduces the influence of the commercial power source and outputs it to the LPF 24c. LPF24c
Is a second-order LC filter having a cutoff frequency of 12 KHz and has traps at 15 KHz and 32 KHz, and mainly removes high-frequency components of 15 KHz or higher, which is an alias frequency of sampling of the ADC 25k, and outputs it to the adjustment amplifier 24d. It is output to the adjustment amplifier 24d.

The adjusting amplifier 24d is adjusted so that the entire sense coil signal amplifying circuit 24 becomes 1250 times.
The level detection circuit 24e is transmitted to the DC 25k.
Output to The level detection circuit 24e detects the output level of the sense coil signal amplification circuit 24 necessary for controlling the input gain switching of the ADC 25k in four stages,
The data is output as 3-bit data to the DSP 26 that controls the ADC 25k.

Since the total length of the sense cable 19 is as long as about 2 m and the potential of the shield 20 becomes unstable and noise may be superimposed on the detection signal due to the stray capacitance of the sense cable 19, the shield drive circuit 24f is connected to the instrumentation amplifier 24.
The potential of the shield 20 is maintained at an intermediate potential between the two signal lines of the sense cable 19 input to a to enhance the shield function.

With the above operation, the detection signal of the sense coil 22k, which is a weak signal, can be amplified with high precision and high magnification. FIG. 8 shows an example of a display screen displayed on the monitor 23 in the endoscope shape detecting device 3 according to the present embodiment.

On the display screen 35, in consideration of improvement of operability, the user can use the function of this device 3 while looking at the display screen of the monitor 23. 8
Shows the stopwatch function. The icon 35a displayed with) is arranged so that the user can select the icon with a pointing device such as a mouse.

In addition, an icon group 35b and the like are arranged in order to facilitate changing the viewpoint (angle and distance at which a still image is viewed) during observation. The icon group 35b is
This is for tilting the bed plane 35c from the front to the back of the screen. The icon at the left end of the icon group 35b is to display the bed plane parallel to the screen (0 °). It is displayed at °, 60 ° and 90 ° (vertical). When the leftmost icon is selected with the mouse, the display on the moving image display portion 35d is instantly displayed in a state of 0 °.

FIG. 9 shows 1 (expressed as an air core solenoid)
3-axis sense coil 22 using the axial source coil 16i
The situation in which the position is detected by j is shown. In the case of endoscopy, the patient 5 is on the bed 4, so the position of the electronic endoscope 6 is always on the bed 4.

In other words, the sensors 3 are provided at the four corners of the bed 4.
If the axis sense coil 22j is provided, the electronic endoscope 6 (the source coil 16 in the
Since i) is present, the quadrant in which the source coil 16i is present is limited for each installed triaxial sense coil 22j.

When the output of one triaxial sense coil 22 when the source coil 16i is driven is Xi, Yi, Zi, the distance from the triaxial sense coil 22 which is the magnetic field strength associated with Xi ² + Yi ² + Zi ^2. Source coil 1
6i will be present. However, the uniaxial coil is generally expressed as a dipole, so that the equal magnetic field surface does not become a sphere but has an elliptical shape as shown in FIG. Therefore, it is unknown which direction the source coil 16 is facing.
The position of i cannot be identified only from the isomagnetic field surface Xi ² + Yi ² + Zi ² by one triaxial sense coil 22.

Therefore, Xj ² + Y measured for each of the three-axis sense coils 22j provided in the bed 4
Use the distance associated with j ² + Zj ² . in this case,
Since the installation position of each triaxial sense coil 22j is known, it can be represented by, for example, one coordinate system fixed to the bed 4. The equal magnetic field surface generated by the source coil 16i is X
Consider that the magnetic field strength represented by s ² + Ys ² + Zs ² is detected by the sense coil 22j and the distance between them is estimated.

Then, assuming an equal magnetic field surface including the magnetic field strength from the magnetic field strength detected by the sense coil 22j, the sense coil 22j exists on the same magnetic field surface with respect to the center source coil 16i. Therefore, the maximum value and the minimum value of the distance from the center to the equal magnetic field surface are Rmaxj and Rminj, respectively, and the sense coil 22j and the source coil 16i are present at the distance between them.

That is, with reference to the sense coil 22j at a known position, the source coil 16i exists inside the maximum distance Rmaxj and outside the minimum distance Rminj as shown in FIG.

Xj, Yj, and Zj measured by the three-axis sense coils 22j and different for each three-axis sense coil 22j.
Since the source coil 16i exists in the overlap of the spherical shells represented by Rmaxj and Rminj corresponding to, the center of gravity of the region can be detected as the coil position.

With this, the position is obtained, and Rmax,
If the difference in Rmin is large, an error may occur.

Therefore, the inclination in the previously obtained volume is obtained by utilizing the fact that the inclination of the source coil 16i is represented in the phase information included in Xj, Yj, and Zj. As a result, the previous position is corrected so that the position becomes more accurate. Further, since the mutual distance between the source coils 16i is known, it may be further corrected by this value.

In this case, as shown in FIG. 11, since the insertion portion 7 of the electronic endoscope 6 is continuous, the inclination (dx / d) of the obtained discrete source coil 16i position (indicated by X) is obtained.
l, dy / dl, dz / dl) should be equal to or approximate to the tangential direction at the source coil position of the curve l interpolated based on the source coil position, so the position may be further corrected.

FIG. 12 shows the source coil 16i in the scope.
The magnetic field generated by the external coil is detected by the external three-axis sense coil 22j, the position of the source coil 16i is obtained from the relationship between the magnetic field strength and the distance between the two points, and the insertion state is set based on the detection of each position of the multiple source coils 16i. Monitor 23 (also referred to as CRT) having a certain insertion portion shape (simply referred to as scope shape)
The flow displayed above is shown. The overall structure of this flow is
The processing can be divided into the following four blocks B1 to B4.

B1: Initialize Bloc
k) This block completes the initialization work for all functions of this program. Specifically, when calculating the existing position of the source coil 16i from the setting of the initial parameters based on the method of outputting the scope shape on the CRT, and the phase information and the amplitude information obtained from the magnetic field strength detected by the hardware. Memory reading of basic data used for the above, initialization of various boards for controlling hardware, etc. are performed. Note that the detailed processing contents will be described later for each block.

B2: Hardware control block (Hardwa
re Control Block) In this system, the position coordinates of the source coil 16i arranged and fixed in the insertion portion 7 of the endoscope 6 are set to the source coil 16i.
Is calculated from the intensity of the magnetic field generated by, and the shape of the insertion portion 7 of the endoscope 6 in the inserted state is estimated based on this. In this block, the source coil 16i is simultaneously driven to generate a magnetic field, the generated magnetic field strength is detected by the sense coil 22j, and the detected output is converted into a form in which the source coil position coordinates can be calculated and output. Carry.

Depending on the driving frequency of the source coil 16i,
The position of the source coil 16i of the electronic endoscope 6 can be known, and the sense coil 22j for detecting the magnetic field strength of the source coil 16i has three orthogonal axes as shown in FIG. Are manufactured so that the planes of the respective coils are parallel to each other, and the magnetic field strength components in the directions of three axes orthogonal to each other for one sense coil 22j can be detected. The detected magnetic field strength data is separated and output into amplitude data and phase data required when calculating the source coil position.

B3: Source position calculation block (Sourcr P
osition Calculate Block) Based on the amplitude data and phase data obtained by the magnetic field detection in the previous block, the relationship between the magnetic field strength and the distance between the two points is used to calculate the position coordinates of the source coil 16i. Carry. First, the amplitude data and the phase data are corrected for the difference in the diameter of the sense coil 22j in the respective axial directions and the positional relationship between the source coil 16i and the sense coil 22j, and the sense coil 22j is corrected. Calculate the magnetic field strength considered to be detected at the installation position.

The distance between the source coil 16i and the sense coil 22j is obtained from the magnetic field strength thus calculated.
However, since the attitude of the source coil 16i in the inserted state (direction of the solenoid coil) is unknown, the position of the source coil 16i can be limited to within a certain spherical shell. Therefore, three or more sense coils 22j are prepared, the overlap of the regions where the source coil 16i can exist is obtained, and the position of the center of gravity of the regions is output as the position coordinates of the source coil 16i.

B4: Image display block (Image Display
Block) Builds the scope shape based on the data obtained as the position coordinates of the source coil and outputs the image on the CRT. On the basis of data, one or more coordinates obtained as the source coil position coordinates are used to construct smooth continuous coordinates as a whole. Modeling processing is performed to make the scope shape look like this continuous coordinate (polygonal column, color gradation,
Saturation, utilization of brightness, hidden line processing, perspective, etc.).

Furthermore, the scope image model displayed on the CRT can be rotated and scaled in any direction,
It can also display body markers that show the viewpoint position of the current display and the head direction of the patient at a glance. The viewpoint position at the end is automatically saved and becomes the next initial viewpoint position. There is also a hot key to remember the viewpoint direction that the surgeon thinks is easy to see. Next, detailed contents of each block will be described.

B1: Initialization block In the first step S11, the graphic page is initialized (the video RAM is initialized). Further, when the scope image displayed on the CRT is updated, if a new image is overwritten, the viewer is given the impression of a flickering image, and the image disappears as a smooth image. Therefore, by constantly switching a plurality of graphic pages to display an image, smoothness like a moving image is realized. In addition, the colors and gradations used are set as follows.

The number of colors that can be used is limited for each hardware, and is assigned in the form of a palette number. However, with the default settings, there are only two gradations. Therefore, in order to realize richer gradation within the range of available colors, the palette is set.

As a result, it is possible to display the image brighter as it gets closer to the viewpoint and darker as it gets farther, and it is possible to give a stereoscopic effect and depth to the image displayed by the insertion section 7 in two dimensions. Of course, increasing or decreasing the number of gradations is arbitrary. In addition, the colors adopted other than gradation are R, G,
It is made from the configuration of B, and it is possible to express subtle saturation and brightness.

In the next step S12, image parameters such as automatic reading of the initial viewpoint position are initialized. The way in which it looks easy to see the scope image depends largely on the operator's preference. If the initial viewpoint position is fixed, the operator has to purposely reset the viewpoint position where the scope image is easy to see, which reduces usability.

Therefore, the desired viewpoint position is saved in the form of a file (parameter file), and the file is read when the program is started, so that the scope image can be viewed from the viewpoint position that is easy for the operator to see immediately after the program starts. The means to do this are provided.

In the next step S13, the principle source data storing the principle for deriving the source coil position is loaded.
This data is reference data or reference information having the following relationship.

The measurement principle is that the output of the uniaxial source coil 16i is detected by the sense coil 22j manufactured in the three orthogonal axes, and the distance between the source coil 16i and the sense coil 22j is obtained from the magnetic field strength. In obtaining the distance between both coils, the maximum magnetic field strength output and the minimum magnetic field strength output due to the difference in the orientation (axial direction) of the source coil 16i are not directly solved from the superfunction indicating the magnetic field distribution created by the uniaxial source coil 16i. We introduced a new distance calculation method that utilizes the magnetic field strength output and

The graph shown in FIG. 13 is the basic data of this distance deriving principle. This is a graph of the data actually measured in the shielded room. That is, the uniaxial source coil 16i and the triaxial sense coil 22
The value of the maximum magnetic field strength detected at the position of the triaxial sense coil 22j (maximum magnetic field strength) when the axial direction of the source coil 16i is changed at each distance value when the distance to j is set to various values. Value) and the value of the smallest magnetic field strength (minimum magnetic field strength value) are plotted and made into a graph, and the upper curve Cu is the maximum magnetic field strength curve and the lower curve Cd is The minimum magnetic field strength curve is shown.

When the distance between the two coils Cu and Cd is small, there is a difference in the value detected depending on the orientation of the source coil 16i, but the distance between the coils is larger than that of the large source coil 16i. Becomes larger, the difference between the detected values becomes smaller. This is because the magnetic field formed by the dipole does not become a spherical surface when the distance is small, but at a distance sufficiently large with respect to the size of the dipole, it becomes almost spherical without depending on the size of the dipole. This result is consistent with qualitative physical phenomena.

Furthermore, when a certain magnetic field strength H is detected,
It is possible to add a limitation that the source coil 16i can exist only in the spherical shell sandwiched between the minimum radius r_min and the maximum radius r_max. Then, in the measurement range of FIG. 13, the distance within this spherical shell (= r_max-r_min)
Is approximately 60 mm without much depending on the value of the magnetic field strength H.
It can be seen from the two curves Cu and Cd that it is about the same.

FIG. 14 (a) shows a measuring method for obtaining the data of FIG. As shown in FIG. 14A, for example, the uniaxial source coil 16 is arranged at a known distance r1 with respect to the triaxial sense coil 22 (where the center of the cube coincides with the origin) arranged at the origin, and this position Change the direction of the source coil 16 (the axial direction) and place it at the origin 3
The magnetic field strength is measured by the axis sense coil 22, and the maximum value H1 and the minimum value H1 'thereof are measured.

That is, when the direction of the source coil 16 is changed, the magnetic field strength detected by the triaxial sense coil 22 changes accordingly, and the maximum value H1 and the minimum value H1 'of those measured values are obtained.

In general, the axial direction of the source coil 16 is the center of the sense coil 22 and the source coil 16.
The state of being coincident with the line connecting (the center of) (Fig. 14 (a)
The maximum value H1 is obtained in the case of the direction of the source coil 16 shown by the solid line), and the minimum value H1 'is obtained in the case of the state shown by the two-dot chain line orthogonal to the source coil 16 shown by the solid line.

Similarly, the value of the distance r1 is changed to r2, and the triaxial sense coil 22 is similarly measured at the distance r2 to obtain the maximum value H2 and the minimum value H2 '. Further, the same measurement is performed by changing the distance, the maximum value and the minimum value obtained at each distance are plotted, and the maximum value and the minimum value are connected by lines so as to interpolate, respectively, as shown in FIG. 14 (b). A curve Cu of the maximum magnetic field strength and a curve Cd of the minimum magnetic field strength are obtained. The data of these curves Cu and Cd are stored in a data storage means such as a hard disk, and when the operation of the endoscope shape display is started, they are transferred to and stored in the DSP memory 27 of FIG. 2, for example, and the DSP 26 becomes necessary. Refer accordingly.

The actual measured values proportional to the magnetic field strength detected by the triaxial sense coil 22 are the signals 22X, 22Y and 22Z respectively detected by the three coils constituting the triaxial sense coil 22. Squared value and summed, 22X ・ 22X + 22Y ・ 22Y + 22Z ・ 22
It is a value obtained by obtaining the square root of Z, and by calibrating (calibrating) the obtained value with a standard magnetic field measuring device (for example, a Gauss meter), an accurate measured value of the magnetic field strength can be obtained. Two curves Cu and C in FIG. 14 (b)
By referring to d, the three-dimensional region in which the source coil 16 exists for the triaxial sense coil 22 can be estimated from the magnetic field strength detected by the triaxial sense coil 22.

For example, when a certain magnetic field strength Ha is obtained by measurement, the distance corresponding to this magnetic field strength Ha is shown in FIG.
From (b), it can be estimated that the value of the magnetic field strength Ha is a three-dimensional region in which the source coil 16 exists in the distance range between the distances ra and ra 'where the curves Cd and Cu respectively intersect. That is, when a certain magnetic field strength is obtained, the values are the minimum magnetic field strength curve Cd and the maximum magnetic field strength curve Cu.
Minimum distance r_min and maximum distance r_m that intersect with
It can be estimated that it is between ax.

It has been confirmed that the measured values in the shielded room and in the ordinary living room are almost the same, and therefore, if the function shape of the curve in the shielded room is obtained in advance, it can be used in other environments. Using the function, the maximum magnetic field strength curve and the minimum magnetic field strength curve in the environment can be accurately determined.

That is, even in a situation where the environment of endoscopy changes, by measuring the magnetic field in advance by a measuring device capable of measuring the magnetic field strengths in the max and min directions at several places in the environment, It becomes possible to obtain the curve data of the maximum magnetic field strength and the minimum magnetic field strength in that environment, and it is possible to save the trouble of obtaining detailed data for each environment by measurement.

The file (max_min data file) in which the data of the maximum magnetic field strength and the minimum magnetic field strength are recorded is loaded, and the correction data is also loaded from the correction data file to perform the following correction.

Sense coil 22j manufactured with three orthogonal axes
Is almost impossible to manufacture with the same core and the same diameter, and the output detection value varies depending on the diameter. Also,
The output value also changes depending on the orientation and direction of the source coil 16i.

Therefore, the magnetic field was actually detected, and the arrangement of the source coil 16i and the sense coil 22j and the change in the magnetic field detection value were examined. As a result, it is possible to correct the difference in the size of the diameters and the relationship of the arrangement of the coils 16i and 22j by simply multiplying the correction coefficients for the respective diameters. Therefore, the initialization block B1 fetches the previously measured correction coefficient for each axis. The result is described in the source position calculation block B3 for calculating the magnetic field strength.

After loading the above-mentioned data, the hardware is initialized in the next step S14. This step S
At 14, the setting contents of the ADC 25k and the like are reset to a setting state corresponding to the use environment. In this way, the hardware is set to the shape calculation enabled state, and the next block B2 is operated.

B2: Hardware Control Block First, in step S21, all source coils 16i are simultaneously driven with high-frequency signals of different frequencies as described above, and all source coils 16i are simultaneously driven.

Then, as shown in step S22, the detection signal detected by each sense coil 22j is sent to each ADC 25.
sample at k. The sampled data is once written in the DSP memory 27. Step S2
As shown in FIG. 3, (the DSP 26) determines whether or not a predetermined number of samples have been made. If not completed, the process returns to step S21, and the source coil 16i is further driven to perform a predetermined number of samples.

When a predetermined number of samples are sampled, the data in the DSP memory 27 is converted into the amplitude data,
Phase data is calculated (see frequency component extraction in step S24 in FIG. 12, amplitude data and phase data in step S25). From the amplitude data and the phase data, the process of the next block B3 is started. First, the calculation of the magnetic field strength in step S31 is performed using the correction coefficient.

Next, in step S32 (source coil 16
Calculation of the maximum distance and the minimum distance (between i and the sense coil 22j) is performed using the maximum and minimum distance data (data in FIG. 13). In this step S32, the magnetic field strength obtained in the previous step S31 is used to perform processing until the maximum distance and the minimum distance between the sense coil 22j and the source coil 16i are calculated.

The fact that there is a proportional relationship between the distance between two points and the magnetic field strength is a very generally known physical phenomenon. However, at one point in a certain space, the l-axis source coil 1
Since the magnetic field strength generated by 6i is generally expressed by a super function, even if the direction of the source coil 16i is known and the magnetic field strength is measured, since there is a relative relationship with the sense coil, the direction and distance in which the source coil 16i exists Is not easy to calculate.

Therefore, when a certain magnetic field strength can be detected,
Let R_max be the distance when it is assumed that the source coil 16i is oriented in the direction in which its output is strongest, and R_min be the distance when it is assumed that the source coil 16i is oriented in the direction in which its output is weakest. Distance R_true between source coil 16i and sense coil 22j
Can be limited within the range of R_min ≦ R_true ≦ R_max.

Magnetic field strength M obtained in the previous step S31
And the already read magnetic field strength data m of the R_max curve are compared, and a point where mb ≦ M ≦ mt is picked up. Assuming that there is a linear change between mb and mt,
R_max is the distance corresponding to the magnetic field strength M at the midpoint.
And

The same applies to R_min. Here, the reason why the mb and mt are linearly changed is because the calculation is simplified, and there is no problem in curve approximation. Further, it is of course possible to derive the function form f (x) of the R_max curve and calculate it as R_max = f (M).

The distance calculating means or method adopted here is an extremely simple means or method that does not require the solution of a complicated super function, although the value of the distance R_true cannot be obtained reliably. Upper 1-axis source coil 1
Even if the direction of 6i is unknown, the source coil 16i
It is a means or method with a wide range of application that can limit the range of existence.

Next, the source coil 16i in step S33.
Position coordinates are calculated. In this step S33, processing from the distance between the sense coil 22j and the source coil 16i to the calculation of the coordinates of the source coil 16i is performed. Source coil 16 when viewed from a certain sense coil 22j
The possible range of i is within the spherical shell surrounded by R_max and R_min obtained in the previous step S32. In order to limit the range in which the sword coil 16i can exist to a smaller space, superposition of the possible regions of the source coil 16i found from the plurality of sense coils 22j is used. Each sense coil 22
For j, the existing region of the source coil 16i obtained from the same source coil 16i always has a region where all of them overlap unless the position of the source coil 16i moves.

The boundaries of such regions are radii R_max and R_mi centered on the respective positions of the sense coils 22j.
It is the intersection of n balls. Since it is the intersection of the spheres,
If there are at least three sense coils 22j, the source coil 16i is R_max, R_ of each sense coil 22j.
Its existence can be limited to a minute region surrounded by eight intersections of a sphere having a radius of min.

The three sense coils 22j are connected to Sa, Sb,
Sc, and Ra_max, Ra_min, Rb, respectively
_Max, Rb_min, Rc_max, Rc_min
Assuming that the distance is obtained, the existence of the source coil 16i is restricted in a minute space having the following eight points as vertices.

Ra-max, Rb_max, Rc_ma
Intersection points of spheres with radius x respectively Ra min, Rb_max, intersection points of spheres with radius Rc_max Ra_max, Rb_min, intersection points of spheres with radius Rc_max Ra_max, Rb_max, intersection points of spheres with radius Rc_min, respectively Intersection points of spheres having radii Ra_min, Rb_min, and Rc_max. Intersection points of spheres having radii of Ra_min, Rb_max, and Rc_min. Radius intersection points Ra_min, Rb_min, and Rc_min of radii. Then, the center of gravity of the minute area surrounded by these eight points is output as the position coordinates of the source coil 16i. Further, as the number of sense coils 22j increases, the source coil 16i
Can be limited to a smaller area, and the position of the source coil 16i can be obtained more accurately.

Since this source coil position limiting method is a simple arithmetic calculation of calculating the intersection of three spheres,
It is an extremely excellent method that does not require the processing time and can limit the existence region of the source coil 16i to a very small region. In this way, the position coordinates of each source coil 16i are calculated, and the position coordinate data of the source coil 16i in step S34 is obtained. The processing of the next block B4 is performed using these data.

B4: Image display block This block B4 is based on the position coordinate data of the source coil 16i, and the scope shape image in the inserted state is C
Responsible for processing up to drawing on RT. Source coil 16
The position coordinate of i is the locus that the inserted scope has passed. Therefore, based on this, the scope shape in the inserted state is estimated. When the insertion shape of the scope can be estimated, the result is drawn on the CRT. At that time, because the 3D scope shape must be displayed on the 2D CRT screen,
It is necessary to devise so that the image can be expressed more three-dimensionally.

Further, if the scope image can be rotated in any direction and the direction from which the scope image is being viewed can be instantly judged, the usability is further improved. In view of this,
In this system, when the key input corresponding to the given user command is performed by the keyboard input process of step S41, it is up to changing the setting parameters and the like according to the contents.

For example, rotation of an image image around an axis such as the x-axis, enlargement of the image image & by the instruction from the keyboard.
Performs processing such as reduction. After that, the scope image depiction processing of step S42 is performed, and the scope image is displayed on the CRT. After that, depending on whether the program is finished or not, if it is not finished, the process returns to step S21,
When the end is selected, the process for drawing the scope image ends.

According to this embodiment, at the time of start-up or when there is a request from the user, the drive frequency of the source coil 16i is optimized, and the detected value in the amplitude data of the detected signal is detected. After performing the process of setting the driving frequency setting data that maximizes the driving frequency, the driving is performed at the frequency determined by using the driving frequency setting data. By performing such a drive frequency optimization before use, even if there is an influence on the device due to a change in ambient temperature or a change over time, signal components with high S / N and high sensitivity are extracted. Since position detection can be performed in a disassembled state, highly accurate position detection and shape display are possible.

(Second Embodiment) Next, a second embodiment will be described. The whole structure is the same as that of FIG. Further, the endoscope shape detection device 3 of the present embodiment has a configuration in which the source coil drive circuit unit 29 and the PIO 30 are separated from each other in FIG. Further, the CPU 31 does not perform the drive frequency setting data changing function 31a.

Therefore, the source coil drive circuit portion 29 'in this embodiment is composed of the frequency oscillation circuit 40' separated from the PIO 30 and the source coil drive circuit 41k as shown in FIG. The source coil drive circuit 41k portion of FIG. 15 has the same configuration as that of FIG.

The configuration of the frequency oscillating circuit 40 'is shown in FIG.
6 is shown. This frequency oscillating circuit 40 'is configured by a DIP switch 40c' instead of the latch 40c in the frequency oscillating circuit 40 of FIG.
It does not have 0d. The structure of each DIP switch 40c 'is shown in FIG. As shown in FIG. 17, the DIP switch 4
, One of the switches S1, S2, ..., S8 of 0c ′ is grounded, the other end is connected to the LCA 40a, and the resistor R4 is connected.
It is connected to the power supply terminal + 5V via 1 to 48, and S1, S2, ..., S8 of the dip switch 40c 'are turned on / off.
The frequency data is set by turning it off.

In this embodiment, the DSP 26 is provided with means for changing the frequency of the reference signal by sweeping it within a predetermined range, and locking the reference signal frequency when the maximum detection signal data is obtained. To form a means for adjusting the frequency of the drive signal to match the frequency of the drive signal.

The other structure is the same as that of the first embodiment. Next, the operation of the part different from that of the first embodiment will be described. In the first embodiment, the source coil drive circuit unit 2
9 drives each source coil 16i with a sinusoidal current having a different frequency, and the respective drive frequencies are stored in the drive frequency data storage means in the source coil drive circuit unit 29.
The CPU (central processing unit) 31 was stored via the IO (parallel input / output circuit) 30, but in this embodiment, it is determined by the setting of the dip switch 40c '.

Further, in the first embodiment, the DSP 26 performs the process of optimizing the drive frequency of the source coil at the time of startup or when there is a request from the user, but in this embodiment, at the time of startup. Or at the request of the user, DSP
26 is a sampling frequency of ADC 25k and FFT
The frequency of the reference signal for the analysis process is optimized. This processing is performed because the detection accuracy of the amplitude data of the detection signal in the extracted data has a great influence on the calculation accuracy of each source coil position, and is always performed for highly accurate position detection.

Specifically, the sampling frequency supplied from the DSP 26 to the ADC 25k is changed for each frequency setting data of the reference signal which is sent from the DSP 26 by incrementing at a predetermined time interval, and further used in the FFT analysis processing. Therefore, after recalculating and storing the reference signal table of the sine wave calculated and stored at the time of initial setting, the amplitude data of the detection signal is stored in the DSP memory. DSP
Reference numeral 26 stores the frequency setting data of the reference signal having the maximum amplitude value in the stored data in the DSP memory 27, and further, based on the frequency setting data of the reference signal, the optimized sampling frequency. And the sine wave reference signal table are used for extraction processing.

As a next step, the DSP 26 extracts 16 source coils 16 from all the extracted frequency components.
The process of calculating the spatial coordinates of i is performed, and the result is transferred to the 2-port memory 28.

After that, the DSP 26 performs (1) sampling of the sense coil signal → (2) extraction of frequency component → (3)
The position calculation of the source coil is repeated. Others operate as described in the first embodiment.

In the present embodiment, since the drive frequency of the source coil may be fixed, as shown in FIGS. 15 to 17, the DIP switch 40 is not connected to the PIO 30.
Although the drive frequency is set by c ', it may be configured as in the first embodiment. In the case of the configuration as in the first embodiment, the latch 40 is executed by the CPU 31 via the PIO 30 in the same manner as the description of the operation of the first embodiment.
The drive frequency is set based on the drive frequency data stored in c. Further, the effects of this embodiment have the same effects as those of the first embodiment.

(Third Embodiment) As described in the first embodiment, since the sense cable has a long total length, the stray capacitance of the entire cable is large and the resistance component of the shield portion is also large. Will end up. Therefore, in order to prevent the noise component from being superimposed on the detection signal, the shield drive circuit that holds the potential of the shield at the intermediate potential of the detection signal is provided.

In order to detect the strength of the magnetic field at one point, 3
A three-axis sense coil 22j configured by arranging two single-axis coils so that their axes are orthogonal to each other and their centers coincide with each other.
However, the three sense cables 19 of the triaxial sense coil 22j were individually driven in the respective shield portions in a state of being wired substantially in parallel and in close contact with each other.

Therefore, when the signal levels detected by the X-axis coil, the Y-axis coil, and the Z-axis coil are remarkably different from each other, the interference due to the difference in the potentials held by the shield portions causes the detection signal. May not be detected accurately. Therefore, the present embodiment aims to more accurately detect the sense coil output in the means for inputting and amplifying the detection signal of the sense coil.

FIG. 18 shows the configuration of the sense coil signal amplifier circuit section 24 in the present embodiment.

Three circular coils 221, 222, 223
And a three-axis sense coil 22j arranged so that their axes are orthogonal to each other and the centers thereof coincide with each other, and a sense coil signal amplifier circuit 24k for amplifying a sense coil detection signal of each axis.
And a sense cable 19a including a twisted pair shield wire that connects both ends of the X-axis coil 221 and the input terminal of the sense coil signal amplifier circuit 24k, and the sense cable 1
Intermediate potential detecting means 43 connected to the two signal lines 9a
a, a sense cable 19b composed of a twisted pair shield line connecting both ends of the Y-axis coil 222 and the input terminal of the sense coil signal amplifier circuit 24, and a sense cable 19b.
intermediate potential detecting means 43b connected to the two signal lines b.
And a sense cable 19c including a twisted pair shield wire that connects both ends of the Z-axis coil 223 and the input terminal of the sense coil signal amplifier circuit 24, and a sense cable 19c.
intermediate potential detecting means 43c connected to the two signal lines of c
And an averaging means 44 which inputs the output signals of the three intermediate potential detecting means 43a, 43b and 43c and supplies the averaged potential to the three sense cables 19a, 19b and 19c. The other configuration is the same as that of the first or second embodiment.

Next, the operation of the sense coil signal amplifier circuit section 24 in the present embodiment will be described. The intermediate potentials between the signal lines of the sense cables 19a, 19b, 19c are detected by the three intermediate potential detecting means 43a, 43b, 43c, and input to the averaging means 44. Averaging means 4
4 calculates an average value from the input three intermediate potentials. Further, the averaging means 44 supplies the calculated average potential to all the shield portions of the three sense cables 19a, 19b, 19c, calculates and holds the average potential.

By this action, since the respective shield portions are kept at the same potential, unnecessary interference is less likely to occur, and the output of each sense coil can be detected more accurately.

That is, when a plurality of magnetic field detecting means are constituted as one set, the potentials of the shield coating portions provided to cover the signal lines in the detection signal transmitting means are kept equal to each other. Superimposition of noise and radiation between the parts and between the signal line and the shield coating are reduced. Other effects are the same as those of the first embodiment or the second embodiment.

(Fourth Embodiment) As described in the first embodiment, since the sense cable has a long total length, the stray capacitance of the entire cable is large and the resistance component of the shield part is also large. Will end up. Therefore, in order to prevent the noise component from being superimposed on the detection signal, the shield drive circuit that holds the potential of the shield at the intermediate potential of the detection signal is provided.

The coil of the triaxial sense coil 22j is
The sensitivity is extremely high so that the weak magnetic field generated by the source coil can be detected. Therefore, even with a very weak magnetic field radiated from the source coil drive circuit 29, if the triaxial sense coil 22j is arranged within a certain distance as viewed from the source coil drive circuit, the radiated magnetic field from this circuit will be emitted from the original coil. There was a possibility that it would be added to the magnetic field and detected.

Therefore, the present embodiment is intended to detect the output of the sense coil more accurately in the means for inputting and amplifying the detection signal of the sense coil. The outline of the configuration of the present embodiment is shown in FIG. For simplification, FIG. 19 shows one source coil 16i and one sense coil 22j.

The source coil drive circuit portion 29 for driving the source coil 16i and the reference potential portion of the source coil drive circuit portion 29 for cutting off the magnetic field emitted from the source coil drive circuit portion 29 are electrically connected. Magnetic shield 45, shield drive circuit 24f electrically connected to magnetic shield 45, and shield drive circuit 24
A sense cable 19 for transmitting a sense coil output to the sense coil signal amplification circuit section 24 having a shield portion connected to f. Other configurations are first
This is the same as the second embodiment or the second embodiment. Next, the sense coil signal amplification circuit unit 2 according to the present embodiment
4 will be described.

When the source coil drive circuit section 29 drives the source coil 16i, a slight magnetic field is generated from the circuit itself due to the current of the drive frequency flowing inside. The magnetic shield 45 uses a ferromagnetic material such as iron, and absorbs and attenuates this magnetic field by a magnetic loss effect such as an eddy current to prevent leakage of the magnetic field to the outside. Further, since the magnetic shield 45 is electrically connected to the reference potential portion of the source coil drive circuit section 29, it is stable in terms of potential. The shield drive circuit 24f holds the potential of the shield portion of the sense cable 19 at this stable potential.

With this operation, in this apparatus, there is no magnetic source other than the source coil around the triaxial sense coil 22j, so that the triaxial sense coil 22j and the source coil drive circuit unit 29 can be arranged close to each other. As a result, the device can be downsized. Others have the same effects as those of the first embodiment or the second embodiment.

(Fifth Embodiment) As one of the methods in the apparatus for detecting the shape of the endoscope, the position of the coil of the generation source is obtained by using magnetism, and the obtained position of the coil is used as the basis. There is a method in which an endoscope shape is displayed by performing interpolation processing on.

In this method, there is a phenomenon that the detected magnetic field strength differs depending on the relative angle of each coil of the magnetic field generation source and the magnetic field detection. Therefore, it is necessary to accurately estimate the relative angle as well as the position. .

Therefore, using the coil position and the relative angle of the coil as tentative values, the difference between the magnetic field strength to be detected at that value and the actually detected magnetic field strength is calculated. An estimation method has been devised in which the position and angle of is determined. Although this method can accurately estimate the true value, it has a problem that the amount of calculation until the estimated value and the measured value are less than or equal to a certain error is enormous, and the processing takes time.

In view of this, in the present embodiment, the endoscope whose position is to be detected is inserted into the body, and in general, considering that the endoscope does not move at high speed,
After obtaining the angle, the subsequent estimation of position and angle uses the obtained values as initial values for estimation.

As described above, since the initial value of the position estimation is the value obtained by the previous position detection, the error between the estimated value and the actually measured value rapidly becomes equal to or less than the threshold value, and The amount of calculation is reduced and the position and angle can be obtained at high speed. If the position has hardly changed, the previous position and angle can be used as they are, and the true value can be obtained at a higher speed.

As described above, even if the algorithm capable of estimating the position and the angle at high speed is adopted, it is necessary to execute all the position calculations when the entire position changes, and therefore, the calculation process is performed. It will take time.
Therefore, in the present embodiment, in order to execute complicated iterative calculation at high speed, in an endoscope shape detection apparatus using a magnetic field, a plurality of processor resources are incorporated and a function of cooperating / parallel operation is incorporated. I chose

Further, since the processing is performed in a distributed manner, in order to ensure the simultaneity of the position data used at the time of drawing the shape of the endoscope, a unit for storing the position data and the data representing the sampling time together, and a plurality of means for storing the data. In order to perform drawing using the latest data of the position data, the coil position is calculated by distributed processing using the latest data group for which the data collection by the position data collection means has been completed, and the obtained coil position is obtained. The endoscope shape detecting device has a built-in means for drawing the entire shape of the endoscope from an angle.

In the present embodiment, when a plurality of processors are used for cooperative operation, naturally distributed parallel processing of processing with a high CPU load is effective for improving the overall processing speed.

Therefore, a case where a plurality of coils are simultaneously driven at different frequencies will be described as an example. in this case,
The process of obtaining the amplitude of the signal for each coil and the phase difference from the reference signal from the collected data places a heavy load on the CPU. In addition, a large amount of CPU resources are also used for the portion for drawing the finally obtained endoscope shape.

The configuration of this embodiment is shown in FIG. A magnetic field generation block including a source coil drive circuit unit (not shown) and a source coil that generates a magnetic field by the source coil drive circuit unit, a triaxial sense coil 22j for detecting the magnetic field, and each axis of the triaxial sense coil 22j. 24 that amplifies the coil detection signal of A, the ADC 25k that converts the analog signal output output from each amplifier 24 into a digital signal, and the position and angle of the source coil that is the magnetic field generation source are detected from the digital signal output from the ADC 25k. A detection block 47 including a CPU 48, a buffer memory 46 that stores sampling time data and position data transferred from the CPUs 48 provided in the plurality of detection blocks 47 in association with each other, and a buffer memory 46.
Drawing CPU 31 for generating drawing data of the shape of the endoscope using the latest data from a plurality of position data, a video RAM 33 for storing the drawing data generated by the drawing CPU 31, a video signal amplifier circuit 34, and Monitor 2
And 3. The source coil drive circuit unit (not shown) has a function or means for optimizing the drive frequency as described in the first embodiment.

Next, the operation of this embodiment will be described. When the CPU 48 reads all the sense coil detection data sampled by the three ADCs 25k, the time at the time of reading is stored as sampling time data. Further, the frequency component corresponding to the drive frequency of each source coil included in the detection data is extracted by FFT processing, and the square root of the sum of squares of the components of the same frequency detected by the coils of the X-axis, Y-axis, and Z-axis is extracted. To calculate. Position calculation is performed using this value to generate position data, and then the position data is stored in the buffer memory 46 together with the sampling time data.

On the other hand, the drawing CPU 31 searches the plurality of source coil position data stored in the buffer memory 46 for one set of position data of each source coil having the same sampling time, and reads it as the latest data. Then, using this data, an image representing the insertion shape of the endoscope is generated and written in the video RAM 33.

Since the processing contents of the respective CPUs 31 and 48 can be simplified by performing the processing in such a dispersed manner, the processing speed of each can be improved.

Of the series of processes performed by the frequency extracting means and the insertion state detecting means in this way, the main processing means executes the processing for generating the display data to be displayed by the display means, and the other processing is performed by the plurality of sub-processes. Since the processing is divided and each processing is executed by one or more sub-processing means and the processing result is transferred to the main processing means, the execution contents of the main processing means or the sub-processing means are simplified and each processing time is reduced. Will be shortened.

Further, for simple and small-scale numerical calculation processing, the function of the CPU 48 is changed to the DSP 2 as shown in FIG.
By performing the processing in 6, further high speed processing can be performed. Others have the same effects as those of the first embodiment.

(Sixth Embodiment) This embodiment is an improvement of the distributed processing configuration of the fifth embodiment.
It has the configuration shown in FIG.

The feature of this embodiment is that the signal input from the magnetic field detecting means is converted by the ADC 25k and the FF is used.
This is because the blocks to be subjected to the T processing have been subjected to distributed processing, and when the blocks are stored in the buffer memory 49, the data blocks representing the sampling time and the data blocks representing the frequency component data are stored in association with each other.

Further, the DSP 50 at the subsequent stage searches for a set of detection data of each sense coil having the same sampling time, reads it as the latest data, performs the position / angle detection processing of each source coil, and buffers the position data together with the sampling time data. It is stored in the memory 46. The subsequent operation is the same as that of the fifth embodiment.

With this structure, higher speed processing can be performed as compared with the fifth embodiment.

Further, in the same way of thinking as this embodiment, A /
By providing another buffer memory for the converted data of D25k, further distributed processing can be performed. In this example, the buffer memory in which this data is stored will be read from the DSP at the subsequent stage as needed to calculate the position / angle.
Therefore, the dual port memory is used so that the write / read bus contention does not occur.

(Seventh Embodiment) This embodiment is an improvement of the position detection algorithm of the first embodiment. Specifically, when position detection is performed for one source coil, in the process of limiting the area where the source coil exists, four sources are determined from the detection values of the three-axis sense coils due to the influence of disturbance and the like. There is a case where all the areas do not include a common area, and the algorithm of the first embodiment cannot detect the position in such a case, and the processing is stopped.

In the present embodiment, when the above-mentioned case occurs, the four areas A, B, C and D described above are used.
After obtaining the intersection point group Pi of the areas A and B, the intersection point group Qi of the areas B and C, and the intersection point group Ri of the areas C and A, ... I tried to find the position by finding the combination of points.

In the first embodiment, the position of the source coil is detected from four points, but the position can be detected from three points. In this case, the three areas A, B and C are detected.
After obtaining the intersection points Pi of the areas A and B, the intersection points Qi of the areas B and C, and the intersection points Ri of the areas C and A, respectively,
In the group of three intersections, the combination of the points that are closest to each other is found and the position is calculated.
Even in such an abnormal case that is impossible in principle, the processing is not stopped, and it is not necessary to restart the device.

Further, the position of the endoscope is determined based on the frequency component signals of at least four sets and having the same frequency, or when the determined position of the endoscope is not a value in the detectable region, If the position obtained by the predetermined additional condition is corrected, the position of the endoscope can be detected more reliably and accurately.

(Eighth Embodiment) In this embodiment, in addition to the display screen of the first embodiment, the viewpoint of a moving image (that is, the angle or distance at which the moving image is viewed) is changed during observation. In order to make it easier, when the icon for changing the viewpoint is dragged by the point device, the viewpoint on the moving image is linearly changed. For example, when the icon on the left end of the icon group 35b in FIG. 8 is clicked with a mouse and dragged in the direction of the icon on the right end, the inclination of the bed plane becomes finer than the step of the above angle.

Note that, for example, in the first embodiment, the source coil 16i is installed in the insertion portion 7, and the source coil 16i
Although it has been described that the shape of the endoscope is detected by detecting the position of i, the present invention is not limited to this.
Place the source coil 16i at a known position around the patient,
Three-axis sense coil 22j side or one-axis sense coil 2
2k may be installed in the insertion part 7 to detect the shape of the endoscope. Further, different embodiments and the like can be configured by partially combining the above-described embodiments and the like, and these also belong to the present invention.

[Additional Notes] 1. In order to detect the insertion shape of the endoscope, a magnetic field generation unit that emits an electromagnetic wave that generates a magnetic field by receiving a high frequency signal, a magnetic field detection unit that receives the electromagnetic wave and detects magnetic field information of the received electromagnetic wave, Frequency extraction means for extracting a predetermined frequency component from the detection signal detected by the magnetic field detection means, and insertion state detection means for detecting the insertion state of the endoscope based on the frequency component signal extracted by the frequency extraction means. Display means for displaying the insertion state detected by the insertion state detection means, detection signal transmission means for transmitting the detection signal detected by the magnetic field detection means to the insertion state detection means, and the magnetic field generation means. A high frequency signal transmitting means for transmitting a high frequency signal to be supplied, and the magnetic field detecting means and the detection signal transmitting means, or the magnetic field generating means and the high frequency signal transmitting means. In the endoscope shape detecting device, one set of which is provided in the insertion portion of the endoscope, a frequency setting signal for setting the frequency of the high-frequency signal to a predetermined value and the frequency of the high-frequency signal are changed within a predetermined range. Frequency setting means for generating a frequency change signal for generating a high frequency signal based on the frequency setting signal or the frequency change signal generated by the frequency setting means, and the frequency setting means for changing the frequency. A frequency storage means for storing the frequency of the high frequency signal when the signal is being generated and the frequency component signal extracted by the frequency extraction means is in a state corresponding to a predetermined one, An endoscope shape detecting device characterized in that the frequency of the high-frequency signal is set to the frequency stored in the frequency storage means.

[0193] 2. To detect the insertion shape of the endoscope,
A magnetic field generating means for receiving a high frequency signal and emitting an electromagnetic wave accompanied by a magnetic field, a magnetic field detecting means for receiving the electromagnetic wave and detecting magnetic field information of the received electromagnetic wave, and a predetermined frequency from the detection signal detected by the magnetic field detecting means. Frequency extraction means for extracting a component, based on the frequency component signal extracted by the frequency extraction means, insertion state detection means for detecting the insertion state of the endoscope, and the insertion state detected by the insertion state detection means A display state to be displayed, a detection signal transmitting means for transmitting the detection signal detected by the magnetic field detecting means to the insertion state detecting means side, and a high frequency signal transmitting means for transmitting a high frequency signal supplied to the magnetic field generating means. The magnetic field detecting means and the detection signal transmitting means, or the magnetic field generating means and the high frequency signal transmitting means are provided in the insertion portion of the endoscope. In the endoscope shape detecting device, the high frequency signal is generated based on a frequency setting means for generating a frequency setting signal for setting the frequency of the high frequency signal to a predetermined value, and the frequency setting signal generated by the frequency setting means. A high frequency signal generating means and a frequency of a reference signal which the frequency extracting means refers to when extracting a frequency component, for changing a frequency of the reference frequency setting signal and the reference signal for setting the reference frequency setting signal to a predetermined value within a predetermined range. In the case where the reference frequency setting means for generating the reference frequency change signal and the reference frequency setting means generate the reference frequency change signal,
And a frequency storage unit that stores the frequency of the reference signal when the frequency component signal extracted by the frequency extraction unit matches a predetermined state, and the reference frequency setting unit ends the generation of the reference frequency change signal. After doing
An endoscope shape detecting apparatus, wherein a reference frequency setting signal for setting the frequency stored in the frequency storage means is generated.

[0194] 3. The endoscope shape detection device according to appendix 1 or 2, wherein the frequency extraction means includes a Fourier transform processing means. 4. The endoscope shape detection device according to appendix 1 or 2, wherein the frequency extraction means includes a synchronous detection means. 5. Note 1 or 2, wherein the insertion state detecting means includes position detecting means for correcting the position obtained by a predetermined additional condition when the obtained position of the endoscope is not a value in a detectable region. Endoscope shape detection device.

6. In the case where a plurality of magnetic field detecting means are configured as one set, each of the detection signal transmitting means is provided with a shield driving means for keeping the potentials of the shield covering portions provided for covering the signal lines equal. The endoscope shape detection device according to attachment 1 or 2. 7. Of the series of processing performed by the frequency extraction means and the insertion state detection means, the processing for generating display data to be displayed by the display means is executed by the main processing means, and the other processing is divided into a plurality of sub-processings. Appendix 1 or 2 the endoscope shape detection apparatus, wherein each processing is executed by one or more sub-processing means and the processing result is transferred to the main processing apparatus.

8. On the screen displayed on the display means, a character display means for displaying a character representing a plurality of adjustment stage values and a selection means for selecting one of the characters are provided. By moving the character in the direction of a character other than the selected character, it is possible to select an intermediate value of the values of the two adjustment steps corresponding to the moving distance. Endoscope shape detector.

[0197]

As described above, according to the present invention, in order to detect the insertion shape of the endoscope, magnetic field generating means for receiving a high frequency signal and radiating an electromagnetic wave accompanied by a magnetic field, and receiving the electromagnetic wave. Magnetic field detecting means for detecting magnetic field information of the received electromagnetic wave, frequency extracting means for extracting a predetermined frequency component by referring to a reference signal from the detection signal detected by the magnetic field detecting means, and the frequency extracting means for extracting An insertion state detecting means for detecting an insertion state of the endoscope based on a frequency component signal, a display means for displaying the insertion state detected by the insertion state detecting means, and a detection signal detected by the magnetic field detecting means. Is provided to the insertion state detecting means side, and a high frequency signal transmitting means for transmitting a high frequency signal supplied to the magnetic field generating means, the magnetic field detecting means and the detecting means. Signal transmission means, or a magnetic field generation means and a high-frequency signal transmission means any one set, in the endoscope shape detection device provided in the insertion portion of the endoscope, the frequency of the high-frequency signal and the frequency of the reference signal Since there is a frequency adjusting means for matching the frequency, the high frequency signal can be changed at a value near the frequency desired to be set by the frequency setting means or the frequency extraction means can be set by the frequency setting means when the device is started or the user desires. The frequency component signal extracted by the frequency extraction means by changing the frequency component near the frequency to be extracted stores a high frequency signal such that the frequency component signal matches a predetermined state such as a maximum value, and then stores it. Since it is possible to adjust the frequency such as setting so that a high frequency signal is generated at the selected frequency, it is possible to always extract the accurate frequency component.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an endoscope system including a first embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of the endoscope shape detection device according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing a basic configuration of a source coil drive circuit section.

FIG. 4 is a circuit diagram showing a specific circuit configuration of a frequency oscillator circuit.

FIG. 5 is a circuit diagram showing a specific circuit configuration of a GAIN circuit.

FIG. 6 is a block diagram showing the configuration of a sense coil signal amplifier circuit.

FIG. 7 is a circuit diagram showing a specific circuit configuration of a sense coil signal amplifier circuit.

FIG. 8 is an explanatory diagram showing an example of a display screen.

FIG. 9 is an explanatory diagram showing how a plurality of sense coils provided around the bed detect the existence range of one source coil in the endoscope.

FIG. 10 is an explanatory diagram showing the shape of an equal magnetic field surface formed by a uniaxial coil.

FIG. 11 is an explanatory diagram showing how the position is corrected from the tilt.

FIG. 12 is a flowchart showing the processing contents of the endoscope shape detection device.

FIG. 13 is a characteristic diagram showing a graph in which the values of the maximum magnetic field strength and the minimum magnetic field strength detected by the sense coil at a known distance between the sense coil and the source coil in the shielded room are measured while changing the distance.

14 is an explanatory diagram of a measuring method and the like for obtaining the data of FIG.

FIG. 15 is a block diagram showing a basic configuration of a source coil drive circuit section according to the second embodiment of the present invention.

FIG. 16 is a circuit diagram showing a specific circuit configuration of a frequency oscillator circuit.

FIG. 17 is a circuit diagram showing a specific circuit configuration of a frequency setting part.

FIG. 18 is a block diagram showing a partial configuration of a sense coil signal amplifier circuit according to a third embodiment of the present invention.

FIG. 19 is a schematic configuration diagram of a main part according to a fourth embodiment of the present invention.

FIG. 20 is a block diagram of an endoscope shape detection device according to a fifth embodiment of the present invention.

FIG. 21 is a block diagram of an endoscope shape detection device according to a modified example of the fifth embodiment.

FIG. 22 is a block diagram of an endoscope shape detection device according to a sixth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Endoscope system 2 ... Endoscope device 3 ... Endoscope shape detection device 4 ... Bed 5 ... Patient 6 ... Electronic endoscope 7 ... Insertion part 12 ... Observation monitor 15 ... Probe 26i ... Source coil 22j ... 3 Axis sense coil 23 ... Monitor 24 ... Sense coil signal amplification circuit section 25k ... ADC 26 ... DSP 28 ... 2-port memory 29 ... Source coil drive circuit section 30 ... PIO 31 ... CPU 31a ... Drive frequency setting data change function 33 ... Video RAM 34 ... Video signal generating circuit

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masanao Hara 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd.

Claims (1)

[Claims] 1. A magnetic field generation means for receiving a high frequency signal and radiating an electromagnetic wave accompanied by a magnetic field in order to detect an insertion shape of an endoscope, and a magnetic field for receiving the electromagnetic wave and detecting magnetic field information of the received electromagnetic wave. Detecting means, a frequency extracting means for extracting a predetermined frequency component by referring to a reference signal from the detection signal detected by the magnetic field detecting means, based on the frequency component signal extracted by the frequency extracting means,
Insertion state detection means for detecting the insertion state of the endoscope, display means for displaying the insertion state detected by the insertion state detection means, and a detection signal detected by the magnetic field detection means on the insertion state detection means side To the magnetic field generating means, and a high frequency signal transmitting means for transmitting a high frequency signal to be supplied to the magnetic field generating means. In the endoscope shape detecting device, one set of which is provided in the insertion portion of the endoscope, a frequency adjusting unit for matching the frequency of the high frequency signal and the frequency of the reference signal is provided. Endoscope shape detection device.