JPH0576531A - Ultrasonic observing device - Google Patents

Abstract

PURPOSE:To reduce the influence of noise and to detect the fine voltages of received signals as well by connecting a substrate to execute the logarithmical amplification/detection of input signals to an ultrasonic oscillator and a substrate to execute the analog/digital conversion of amplified received signals by a means equipped with an impedance. CONSTITUTION:The received signals from a probe are supplied through a connector 2 connected to a transformer 4, and the output terminal of the transformer 4 is connected to a log amplifier 5 of a first analog ground. The output of the log amplifier 5 is passed through a detection circuit 6, variable amplifier 7, attenuator 8 and buffer circuit 9 and guided through a coaxial cable 10 to a second analog ground 11. At the second analog ground 11, inputted signals are passed through a low-pass filter 13, converted to digital signals by an A/D converter 14, latched by a latch circuit 16 of a digital ground 15 and inputted to a DSC 17. Thus, digital noise is attenuated, and the resolution of ultrasonic tomographic images can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is an ultrasonic observation in which a probe having an ultrasonic transducer at the tip of an insertion portion is inserted into a subject and the ultrasonic transducer is driven to obtain an ultrasonic tomographic image. Regarding the device.

[0002]

2. Description of the Related Art An ultrasonic observation apparatus inserts an insertion portion of a probe into a body cavity, a blood vessel, or the like, and drives an ultrasonic transducer provided in the insertion portion to remove a probe from an object to be inspected. Ultrasonic diagnosis is performed by receiving a reflected echo, processing the signal, and obtaining an ultrasonic tomographic image. The reception signal system of such an ultrasonic observation apparatus has a configuration as shown in the schematic diagram of FIG.

According to this structure, a program (not shown)
The reception signal supplied from the probe is input to the connector 32 located in the subject circuit ground 31. The received signal input to the connector 32 is input to the log amplifier 35 located in the secondary circuit ground (analog ground) 34 via the transformer 33. In the log amp 35, for example, 100 mV to 1 V,
Received signal with wide dynamic range of 80db is 100mV
Convert to ~ 1V, 20db signal.

[0004] The converted received signals, peak of the received signal including a carrier signal of about a detection circuit 36 for example 20MH _Z -
Ho a click - field and by detecting, and DC7MH _Z signal of about. The gain of the detected signal is controlled by the operator by the variable amplifier 37, or the gain is controlled with respect to time so as to compensate for the attenuation of the ultrasonic waves. The received signal that has been controlled is supplied to a contrast circuit that adjusts the signal level difference by increasing or decreasing the amplitude with respect to the input signal range to the A / D converter which will be described later with the attenuator 38. Is entered.

Next, the buffer circuit 39 outputs the signal with a low impedance, passes through a low-pass filter 40 matched to the frequency from a probe (not shown), and then outputs A /
The digital signal is converted by the D converter 41. The signal converted into the digital signal is latched by the latch circuit 43 located in the secondary circuit ground (digital ground) 42, and then memory-scanned by the DSC (digital scan converter) 44, converted into the television signal and displayed. Output to the container.

[0006]

The signal system of the ultrasonic observing apparatus according to the above-mentioned conventional example has a connector 32 to a latch circuit 43.
The circuits up to were mounted on one board. Also, D
The SC 44 is a digital circuit, which operates with level signals of 0V and + 5V and a clock signal as shown in the signal waveform of FIG. 9A. The DSC 44 is an integrated memory,
A clock signal that operates the memory runs throughout the digital circuit. Therefore, due to the impedance of the return current and the digital ground 42, the digital ground 42 is
Like the signal shown in FIG. 9B, the signal is shaken by noise of about 100 mV.

Since the digital ground 42 and the analog ground 34 are connected via the A / D converter 41, the analog ground 34 is swung by the digital ground 42. 10 and 11 are diagrams for explaining the state. As shown in FIG. 10, the A / D converter 41 is provided with an analog power supply 45, a digital power supply 46 and terminals for the analog board 34a and the digital board 42a. When current is supplied to the terminal from the analog power supply 45 and the digital power supply 46, the current from the analog power supply 45 returns to RET of the analog power supply 45.

On the other hand, if the current from the digital power supply 46 all returns to the RET of the digital power supply 46 as shown by the solid line, the analog board 34a will not be shaken and there will be no problem. As shown by the broken line, the part passes through the inside of the A / D converter 41 and the analog power supply 4
It flows to RET of 5.

Further explaining according to FIG. 11, R _D is shown in FIG.
The common impedance of the digital ground 42 including the impedance between the digital grounds 42 and the impedance between the lead lines from the digital ground 42 to the ground of the digital power supply 46. Also, R
_i is the impedance between the analog ground 34 and the digital ground 42 inside the A / D converter 41. _RA
Is the impedance between the analog ground 34 and the lead from the analog ground 34 to the ground of the analog power supply 45.
The common impedance of the analog ground 34 including the impedance between the lines is used.

A digital current flows from point a through R _D to RET of the digital power supply. The other one flows from the point a through R _i, and then through the point b and R _A to the analog power supply. Then, when the noise as shown in FIG. 8A occurs at the point a, the point b is divided by R _i and R _{A in} FIG. 8B.
Noise appears as shown in. This noise is induced from the digital board 42a in FIG. 10 to the analog board 34a and reaches several tens of mV. If the analog ground is shaken by this noise, the received signal is a signal from several hundred μV, so the noise is buried and cannot be detected.

The present invention is proposed to solve the above-mentioned problems, and provides an ultrasonic observation apparatus capable of detecting a minute voltage of a received signal without inducing an analog ground by digital noise. The purpose is to do.

[0012]

In order to achieve the above-mentioned object, the present invention inserts a probe provided with an ultrasonic transducer at the tip of an insertion portion into a subject and drives the ultrasonic transducer. In an ultrasonic observation device that is configured to obtain an ultrasonic tomographic image,
The first to logarithmically amplify and detect the input signal to the ultrasonic transducer
The above-mentioned substrate, a second substrate for converting the amplified received signal into an analog signal and a digital signal, and an ultrasonic observation apparatus in which the first substrate and the second substrate are connected by a connecting means having impedance. ..

[0013]

With this structure, the digital noise generated from the DSC is less likely to be guided to the analog substrate, and the received signal is not buried in the noise, so that a weak signal can be detected. Become.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the outline of the present invention will be described with reference to FIGS. 4 to 6. First analog board 19 and second analog board 20.
Is connected via a coaxial cable 25, and the second analog substrate 20 and the digital substrate 21 are connected to the A / D converter 22.
Connected via. Power is supplied to the terminals of the A / D converter 22 from the analog power supply 23 and the digital power supply 24. Then, as shown by the broken line, a part of the noise-laden current flows from the digital power source 24 through the inside of the A / D converter 22 to the second analog substrate 20. This current flows to RET of the analog power supply 23, but part of the current flowing from the digital board 21 to the second analog board 21 flows to the first analog board 19 through the coaxial cable 25, and the analog power supply 23 Ret.

FIG. 5 is an equivalent rewriting of FIG. R _D is the common impedance of the digital ground, R _i is the impedance between the digital ground and the analog ground of the A / D converter 22, and R _A is the second impedance.
R _A -1, which is a common impedance of the analog board 20.
Is a common impedance of the first analog board 19,
R _W coaxial Ke - it is a dance - Inpi between the ground of the cable 25. The current carrying the noise generated at a ₁ is
It flows through R _D to RET and also through R _i to reach a ₂ . At a ₂ , the voltage is divided by the combined resistance of R _i and R _A , R _A -1, R _W , and becomes smaller as shown in FIG. 6A.

Further, the current passing through a ₂ passes through R _A and becomes RE.
Reach T, pass R _W , pass point b, R _A
-You will reach RET through -1. In this case, the noise waveform at the point b is divided by R _W and R _A -1 and becomes small as shown in FIG. 6B. As described above, according to the present invention, by providing the impedance between the first analog board 19 and the second analog board 20, it is difficult for noise from the digital board 21 to flow to the first analog board 19 and a small amount of noise is generated. The received signal can also be detected.

Each embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic diagram showing a reception signal system of the ultrasonic observation apparatus according to the first embodiment. A reception signal from a probe (not shown) is supplied through the connector 2 located on the patient ground 1. Connector 2
Is connected to the transformer 4 and separates the patient ground 1 from the first secondary circuit ground (first analog ground) 3. The output end of the transformer 4 is connected to the log amplifier 5 located in the first analog ground 3.

The output of the log amplifier 5 is connected to the detection circuit 6, and the output of the detection circuit 6 is connected to the variable amplifier 7. The variable amplifier 7 is supplied with control signals of STC and GAIN from the outside, and the output of the variable amplifier 7 is connected to the attenuator 8. Attenuator 8
Then, the signal is input to the contrast circuit that adjusts the level difference between the signals. The output of the attenuator 8 is input to the buffer circuit 9 and the second signal is transmitted via the coaxial cable 10.
Of the secondary circuit ground (second analog ground) 11. The above connector 2 to the connector 12 of the coaxial cable 10 are mounted on one board.

In the second analog ground 11, the input signal passes through the low pass filter 13, and the A / D converter 1
4 is input. The signal converted into the digital signal by the A / D converter 14 is latched by the latch circuit 16 located in the third secondary circuit ground (digital ground) 15 and input to the DSC 17.

In this embodiment having such a configuration,
A received signal as shown in FIG. 2A is input to the connector 2. The received signal has a carrier signal 20MH _Z, V
It is a signal of several 10 mV in _pp . Next, this received signal is logarithmically amplified by the log amplifier 5 via the transformer 4 so that the amplification factor varies depending on the magnitude of the amplitude as shown in FIG. 2B. By doing so, the difference between the large signal and the small signal is reduced, and the dynamic range is compressed. In this case, V _pp of the received signal is amplified to several V.

Next, the received signal is full-wave rectified by the detector 6 as shown in FIG. 2C, and the carrier signal is taken through the low-pass filter 13. Therefore, FIG. 2C corresponds to FIG. 2B.
, And V _pp becomes several V. Next, as shown in FIG. 2C, the bias for STC and GAIN control is set from the outside by the variable amplifier 7. For example, the waveform cut out at a in FIG. 2C becomes FIG. 2D1, and the waveform cut out at b becomes FIG. 2D2. As the point of b is lowered, a small signal is detected and GAIN is raised. On the other hand, if it is lowered too much, noise will come in, so the operator will set the point b as appropriate.

Next, the attenuator 8 increases or decreases the signals of FIG. 2D1 and D2 (FIG. 2E1) to adjust the contrast (FIG. 2E2). Such a signal is input to the second analog ground 11 via the buffer circuit 9 and the coaxial cable 10. The signal (several V) input to the second analog ground 11 is passed through the low-pass filter 13 in order to obtain the carrier signal that the detector 6 cannot completely remove. The signal passed through the low-pass filter 13 is
It is input to the A / D converter 14 and converted into a digital signal.
Latch that value with the clock signal from DSC17
Transfer to SC17.

The DSC 17 supplies a clock signal for operating the A / D converter 14 and the latch circuit 16. In addition, a common ground is used for exchanging data with the latch circuit 16. Then, the ground noise (several 100 mV) of the DSC 16 substrate flows through the A / D converter 14 to the second analog ground 11. The noise here is attenuated to about several tens of mV by the internal impedance of the A / D converter 14. In this case, since the signal level on the substrate of the second analog ground 11 is as high as several V, this noise does not affect much.

Further, the noise flowing from the substrate of the second analog ground 11 to the substrate of the first analog ground 3 through the coaxial cable 10 is several mV or less, and the noise of several hundred mV to several V input to the log amplifier 5. Several hundred mV for signal
Although the order signal is somewhat buried in noise, it is possible to detect a minute received signal as compared with the conventional one.

FIG. 3 shows a second embodiment of the present invention. In this embodiment, a ferrite core 18 is provided on the coaxial cable 10 shown in FIG. Other configurations are similar to those of the first embodiment. Generally, the ferrite core 18 has a property that the impedance becomes high with respect to an arbitrary frequency. In the first analog ground 3, the reception signal excluding the carrier signal is sent to the second analog ground 11 via the coaxial cable 10, so that the frequency component of the signal is DC1.
It is about 0MH _Z. Further, noise generated in the substrate of DSC17 is located number 10 MHz _Z and high on a basic clock signal and ringing of 40MH _Z.

Therefore, as in this embodiment, the coaxial cable 1 is used.
The provision of a ferrite core 18 which dance becomes high, becomes digital noise is less likely to flow from the second analog ground 11 to a first analog ground 3, the noise is a few 100mv O - - 0 Inpi from a frequency of about 10 MHz _Z da - decreasing To do. However, since the received signal has a different frequency band, no attenuation occurs. Thus, DSC1
It becomes difficult for the digital noise from 7 to be guided to the substrate of the first analog ground 3, and it becomes possible to detect a minute received signal.

[0027]

As described above, according to the present invention, by providing the connecting means having the impedance, the digital noise generated from the DSC is attenuated and is less likely to be induced in the analog substrate which handles a signal of the order of several 100 μV. The received signal is not buried in noise.
Therefore, even minute reception signals can be detected, the resolution of the ultrasonic tomographic image can be improved, and appropriate ultrasonic diagnosis can be performed.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a signal receiving system of an apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a state of a signal waveform.

FIG. 3 is a schematic diagram of a signal receiving system of an apparatus according to a second embodiment of the present invention.

FIG. 4 is a diagram for explaining the outline of the present invention.

FIG. 5 is a diagram for explaining the outline of the present invention.

FIG. 6 is a diagram for explaining the outline of the present invention.

FIG. 7 is a schematic diagram of a signal receiving system according to a conventional example.

FIG. 8 is an explanatory diagram of signals for explaining a conventional example.

FIG. 9 is an explanatory diagram of signals for explaining a conventional example.

FIG. 10 is a diagram for explaining a conventional example.

FIG. 11 is a diagram for explaining a conventional example.

[Explanation of symbols]

 1 Patient Ground 2 Connector 3 First Analog Ground 4 Transformer 5 Log Amplifier 6 Detector 7 Variable Amplifier 8 Attenuator 9 Buffer Circuit 10 Coaxial Cable 11 Second Analog Ground 12 Connector 13 Low Pass Filter 14 A / D Conversion Device 15 Digital ground 16 Latch circuit 17 DSC

Claims (1)

[Claims] 1. An ultrasonic observation apparatus in which a probe having an ultrasonic transducer at the tip of an insertion portion is inserted into a subject and the ultrasonic transducer is driven to obtain an ultrasonic tomographic image, The first to logarithmically amplify and detect the input signal to the ultrasonic transducer
The above-mentioned substrate, a second substrate for converting the amplified received signal into an analog signal and a digital signal, and the first substrate and the second substrate are connected by a connecting means having an impedance. ..