JPS61122845A - Measurement of temperature or pressure in living body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for measuring temperature or pressure in a living body, and a method for automatically measuring fF.

(Prior art) Conventionally, in order to measure the temperature of various parts of a living body for the purpose of biological or medical research or especially cancer treatment, a non-powered probe implanted in a living body for a long period of time and a measuring device outside the living body are used. A method has been proposed for measuring temperature without a wired connection.

The above-mentioned temperature measurement method involves surgically implanting a probe with a crystal oscillator fully connected to the antenna coil at a desired location within the body, or passing it into the digestive tract and injecting electromagnetic waves at the desired frequency from outside the body. The irradiation energy is radiated to the crystal oscillator via the antenna coil, and the energy absorption when it resonates is observed, or the oscillation of the quartz crystal immediately after the electromagnetic energy irradiation is stopped. There is a method of receiving the child's reverberations through the antenna coil.

However, in any of the above methods, when electromagnetic energy is emitted from the outside of the living body, an energy absorption phenomenon, the so-called dip phenomenon, occurs at a frequency that matches the resonance circuit that constitutes the in-vivo probe! Since the reverberation of the resonant body within the in-vivo probe that occurs in a short period of time after the electromagnetic energy is emitted is detected, the target level or range is extremely small, making it difficult to observe or There was a flaw in that it was extremely difficult to measure.

Furthermore, when this measurement is fully automated and the aforementioned dip point or the aforementioned resonance point is fully automatically tracked, information having a correlation between the frequency of the irradiated electromagnetic wave and the resonance characteristic of the probe of the circuit under test is extracted, and the Although it is necessary to control the oscillation frequency of the electromagnetic waves using information, generally such
Since the coupling between the -b and the external measurement circuit is extremely weak, it is difficult to obtain both of this information using the conventional measurement methods described above, making them unsuitable for automatic measurement.

(Object of the Invention) The present invention has been made in view of the problems of the conventional methods for measuring in-vivo temperature, pressure, etc. It is an object of the present invention to provide a complete measurement method that is capable of detecting resonance frequencies and is also extremely convenient for automatically tracking resonance points.

(Summary of the Invention) The present invention takes all of the following measures for this purpose. That is, as described above, FM or PM modulation is applied to the electromagnetic waves irradiated to the probe from outside the body using a low frequency signal, and the AMf harmonic distortion mediation component that occurs in the modulated electromagnetic waves near the resonant frequency of the glove is extracted. The center frequency of the electromagnetic wave oscillator is controlled by the component signals.

(Example) The present invention will be described in detail below based on an illustrated example.

FIG. 1 is a block diagram showing an embodiment of an in-vivo temperature measuring device according to the present invention.

In the same figure, 1 is the crystal camera X and the antenna coil lvL.
+ and an antenna coil L2 facing the probe outside the living body, and an AM detection circuit 4 at the output antenna coil of a low frequency oscillator 2.
is added, and its output is inputted via an amplifier 5 to a synchronous detection circuit 6 which uses the output of the low frequency oscillator 2 as a synchronous signal, and the oscillation frequency of the CO is controlled by the output. It is.

The in-vivo temperature measuring device configured as described above operates as follows.

That is, FIG. 2 shows the resonant frequency f of the probe.

FIG. 3 is a waveform diagram showing a state of A M f-toned distortion that is applied to irradiated electromagnetic waves in the vicinity.

Now, the low frequency signal is 80Hz, and the frequency deviation is ±2K.
If the Hz electromagnetic wave frequency is variable from 19 MH2 to 21 MHz and the resonant frequency of the probe is fo = 20 MHz, the electromagnetic wave tuned to the frequency oscillates at a period of 80 Hz over ±2 KH2 from its center frequency.

Therefore, the point where the center frequency is Δf lower than the resonance point fO on the resonance characteristic curve of the probe ((l, fO(b) and Δ
The AM9 tone distortion of the arrow when located at the three high points (c) is indicated by a cross mark in the same figure. It exhibits a waveform like this.

This is because the electromagnetic energy is absorbed by the resonant circuit of the probe, and at this time, a waveform receiving AM modulation as shown in Figure 3 (cl fdl (el) appears.

That is, the $3 figure is the above l! The signal waveforms of each part of the block diagram shown in Figure 1 are shown (al is the waveform of the low frequency oscillator 2, and (b) is the electromagnetic wave that has been FM modulated by the low frequency signal and is the waveform of the carp A/L2. The signal waveform applied to, (
cl(di and (e) are the probe resonance characteristic curves t() (b) and (→) of the probe resonance characteristic curves t() and (→) in Figure 2 of the previous section, respectively.
This is a waveform that occurs at both ends.

Furthermore, when the waveform IAM of these (cl (dl (el)
The preparation ingredients are extracted.

As is clear from the figure, each AM modulation waveform differs depending on where the center frequency of the electromagnetic wave is located on the resonance characteristic curve of the probe. In this case, when the frequency deviation is on the + side, the level becomes small, and when it exceeds the resonance point, double distortion occurs, and on the - side, the level increases, and moreover, there is a second-order KfO point where the level increase on the - side is large. In (b)! becomes the minimum level at the deviation - that is, fo, and the level increases regardless of the deviation within ±Δf, so the AM distortion frequency becomes twice, that is, 2fa=160 Hz.

On the other hand, at the point (c) where Δf is higher than fot: included in the frequency deviation, the situation is completely opposite to the above (a).

Therefore, by detecting this change by some means, it is possible to identify at which point on the resonance characteristic curve of the probe the center frequency of the electromagnetic wave at that time is located.

In this embodiment, the thus demodulated waveform is synchronously detected as the low frequency signal in the synchronous detection circuit 6, and then the waveform is shaped into the following waveforms as shown in Figure 3 (il (jl (kl)). Obtain a square wave corresponding to the AMill distortion of
The probe is configured to detect the duty ratio of the rectangular wave, and the duty ratio at the resonance point fO of the probe is 1:1.The frequency at that time is detected and the temperature inside the living body is measured. It is something to do.

Further, by integrating the rectangular wave and converting it into a DC voltage, a DC voltage corresponding to the duty ratio described above is obtained, and this value corresponds one-to-one to each point on the resonance characteristic curve of the globe.

That is, at +fO, the relative value becomes 0.5v, and f.

The lower value is 0.5V or less, and the higher value is 0.5V or more.

Therefore, if the frequency control voltage of the vCO is controlled using the DC voltage sound described above, each of these blocks will form a closed loop, and the center frequency of the electromagnetic wave can be automatically adjusted to the resonance point fo of the probe. Become.

In other words, if the closed loop is fully activated so that the aforementioned DC voltage becomes O, SV, or this DC voltage output is input to a comparator with Q, 5Ve reference voltage, and the difference output becomes O, the servo control loop A system can be constructed and used to automatically measure the frequency of the resonant point fo of the probe as it moves with temperature.

If a servo system is constructed using the present invention in this way, it will have the following features compared to a system using a conventional 7-speed lock loop (PLL) i.

In other words, a conventional PLL detects the phase of a signal in a closed loop and converts the difference into a DC signal to form a servo system, and extracting phase information for -throw requires a high-level signal. On the other hand, since the present invention extracts AM distortion occurring in FM waves, this is possible even with relatively low level signals.

Furthermore, comparing the loop sensitivity and lock range of both 9, it is found that in PLL, the frequency can be varied over the entire frequency range, for example, 2 MHz.
In the present invention, the above-mentioned frequency deviation, for example ±2 KHz, is the full scale and is twice the modulation signal frequency, for example 160 Hz. You can understand that if you extract or detect a waveform duty ratio of 1:1, the lock range and full scale ratio mentioned above will become smaller, and the control of the system will be much easier than with a conventional PLL. .

It is clear that the above-mentioned embodiment is a specific example of the present invention, and that the present invention is not limited thereto, and that there are various other implementation methods. For example, the low frequency signal may be a left-right symmetrical wave such as a triangular waveform, and the synchronous detection circuit may also be a synchronized phase detection circuit.

Furthermore, the present invention is not limited to detecting the resonant frequency of a circuit under test, but also detects, for example, when the characteristic changes at a station point of a maximum or minimum value, the change can be replaced with a change in frequency. It will be obvious that the present invention can be applied to detecting the stopping point of I/Pedanos or any stopping point of a change in current, voltage or other physical change.

Another application example of the present invention is to detect the resonant frequency of an element or circuit whose resonant frequency changes depending on pressure using a device configured in the same manner as the block diagram shown in the above embodiment. For example, the pressure can be detected by the same method as described above, and this method is effective.

Further, the above example shows a case where a dip point of a resonant circuit is detected, but the present invention is not limited to this, and it is also possible to detect a maximum point of a change in a physical quantity. In this case, by making the antenna coil of the external circuit and the AM detection circuit resonate in series and lowering their innovation dance, it is possible to detect the maximum point of the physical quantity change exhibited by the circuit under test.

(Effects of the Invention) Since the present invention is configured and functions as explained above, it is convenient as a means for detecting a stopping point when a certain physical quantity changes with a stopping point, and furthermore, it is useful as a means for detecting the stopping point when a certain physical quantity changes with a stopping point. It is extremely convenient for measuring.

In particular, it is extremely effective in accurately detecting physical change information even when the information is very small, such as when extracting information from an in-vivo probe when measuring the temperature inside a living body.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIGS. 2 and 3 are waveform diagrams for explaining the operation of each part of the block diagram shown in FIG. 1. 1......Crystal oscillator, 2...
...Low frequency oscillator, 3... Voltage controlled oscillator (VCO). 4...--AM detection circuit, 5...
····amplifier. 6......Synchronized detection circuit, L+ and L
2. Yuyu... Coil. Patent applicant Toyo Tsushinki Co., Ltd.

Claims (1)

[Scope of Claims] 1. A probe composed of a resonant circuit that is dependent on temperature or pressure, etc. is implanted in a living body, and electromagnetic energy of a predetermined frequency is applied from outside the living body to determine the resonant frequency when the probe resonates. In this method, the electromagnetic waves are subjected to frequency modulation (FM) or phase modulation (P) using a low frequency signal.
M) At the same time, the center frequency of the electromagnetic wave is changed, and the resonant frequency of the probe is detected by detecting the amplitude modulation (AM) distortion that the modulated electromagnetic wave receives in the vicinity of the resonant frequency of the probe. A method for measuring temperature, pressure, etc. inside a living body, characterized by measuring temperature, pressure, etc. 2. The configuration of the extracorporeal device that detects AM distortion of the electromagnetic waves,
An output obtained by applying a voltage controlled oscillator circuit (VCO) output subjected to FM or PM with a low frequency signal to an antenna coil to which an AM detection circuit is added, and synchronously detecting the output of the AM detection circuit with the low frequency signal. The resonant point of the probe is automatically tracked by configuring a closed loop to control the frequency control voltage of the voltage controlled oscillation circuit. Measuring method.