JPH0618574B2 - Ultrasound endoscopy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an ultrasonic wave for medically observing the inside of a body cavity using a plurality of ultrasonic transducers (hereinafter, simply referred to as “transducers”). The present invention relates to an endoscope device, and particularly to a receiving circuit of this device.

[Conventional technology]

For example, as disclosed in Japanese Patent Application Laid-Open No. 61-11026, there has been proposed an endoscope apparatus in which two transducers having different frequencies are installed in one ultrasonic probe. This one transducer possesses a higher resonant frequency than the other and is thus designed to have a focal point at close range. By driving such a transducer, the images obtained from the transducers having the respective characteristics are combined to obtain image information from a short distance to a long distance.

[Problems to be solved by the invention]

In the above-mentioned conventional endoscope apparatus, two transducers are simultaneously driven to collect ultrasonic echo information and combine them. Therefore, since two sets of transmission and reception circuits are required, there is a drawback in that it is structurally difficult to install as an endoscopic device as compared with an external ultrasonic diagnostic device. That is, there is a drawback that miniaturization cannot be realized.

Further, since the two transducers are simultaneously driven, there is also a problem that an ultrasonic echo (reflected wave) from one transducer mixes into the other transducer as noise. That is, when the received echo signals from both transducers are received, the characteristics of these signals are different from each other, so that they appear as noise on the image.

Therefore, an object of the present invention is to provide an ultrasonic endoscopic device which eliminates the above-mentioned various drawbacks of the related art and prevents the mixing of noise.

[Means and Actions for Solving Problems]

The present invention provides a plurality of transducers having different ultrasonic characteristics, and to these transducers, a common receiving circuit is connected via a common switch means, and an ultrasonic endoscope apparatus in which respective transmitting circuits are connected, The switch means is controlled so that only a predetermined one of the plurality of transducers is activated and the remaining transducers are inactivated.

According to the present invention, there is an effect that it is possible to prevent mixing of a signal from a transducer other than the intended one.

〔Example〕

 The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a circuit diagram of an embodiment of the ultrasonic endoscope apparatus of the present invention.

Overall Circuit Configuration Two transducers 1 and 2 having different ultrasonic characteristics, for example, resonance frequencies, are rotatably provided, and these transducers 1 and 2 are connected to a common reception amplifier 4 via a switch means 3. Further, these transducers 1 and 2 are connected to transmission circuits 5 and 6 which generate drive signals having frequencies tuned to their respective resonance frequencies. These transmitting circuits 5 and 6
Is connected to a transmission selection circuit 7, which is connected to a transducer selection switch 8 and an observation device (hereinafter referred to as a monitor) 9.

Since this transducer selection switch 8 is also connected to the switch means 3, the predetermined transducer 1
Alternatively, it is designed such that when 2 or 2 is switched, the corresponding transmission circuit 5 or 6 is activated via the transmission selection circuit 7.

Further, a transmission signal is sent from the monitor 9 to the transmission selection circuit 7. The connecting line from the transducer select switch 8 to the monitor is for displaying the resonant frequency of the transducer currently selected and driven.

Switch Means Next, referring to FIG. 1, a specific circuit of the switch means 3 which is a feature of the present invention will be described.

The basic configuration shown in FIG. 2 has two sets of transducers Tr.
Diode switch circuits (D ₁ , D ₂ : D ₃ , D ₄ ) for ₁ (corresponding to 1 in FIG. 1) and Tr ₂ (corresponding to 2 in FIG. 1) and switches for them, respectively. It is characterized in that transistor control circuits (T ₁ , T ₂ , T ₃ ) are connected.

Next, the operation when the transducer Tr ₁ is selected will be described.

First, when the switch SW ₁ is in an open state, the current flowing through the diode (PN junction) between the emitters and the bases of the transistors T ₂ and T ₃ causes the charging current of the capacitor C ₃ connected to these common bases. And as a result, the capacitor C ₃ is charged to the power supply voltage + V _cc at the point D. At this time, these transistors T ₂ and T ₃ are in a reverse bias state and turned off. On the other hand, the transistor T ₃ is grounded through the path of the resistor R ₄ , the diode D ₃ , the inductance L ₂ , the resistor R ₂ and the resistor resistors R ₄ and R ₇ (GN
D), the potential at point F (that is, collector potential) becomes the ground level.

From the point B, the drive signal for the transducer Tr ₂ is connected so as to be input from the transmission selection circuit 7, but as described above, the other transducer T is currently used.
No drive signal is provided because r ₁ is selected.

On the other hand, since the transistor T ₂ is in the OFF state, its collector is at the ground level due to the resistor R ₆ .
As a result, a forward bias is applied to the transistor T ₁ via the resistors R ₉ and R ₆ , so that the transistor T ₁ is turned on. Resistance R ₉
When R ₁ = R ₈ << R ₅ is set and the ON resistance of the transistor T ₁ is small, the potential at the point E is R ₃ , D ₁ , L ₁ ,
It depends on the currents flowing through R _1, R ₃ , D ₂ and R ₃ .

The diodes D ₁ and D ₂ form a diode switch, and the forward bias is applied to them as described above. Therefore, the signal from the transducer Tr ₁ driven via the point A is output point C. Will be output to. This output is amplified to a predetermined level by the reception amplifier 4 in FIG. 1 and displayed on the monitor 9 as an ultrasonic image.

In this case, considering the DC potential, point F is the ground level,
Since the point E has a certain positive potential, a reverse bias is applied to the other diode switch D ₃ , D ₄ D ₄ , and the diode switch D ₃ , D ₄ is turned off. As a result, the received signal from the transducer Tr ₂ is output at the output point C.
Not supplied to.

Next, when the switch SW ₁ is closed, the transistors T ₂ and T
The base of ₃ is grounded through a resistor R ₁₀ . As a result,
A forward bias is applied to the transistor T ₃ to turn it on, and the diode switches D ₃ and D ₄ are both turned on.
It becomes a forward bias state. As a result, the reception signal of the transducer Tr ₂ is supplied to the output point C. In this case, since the transducer Tr ₂ is in the ON state, the potentials of the resistors R ₆ and R ₉ are almost equal to the power supply voltage, that is, the potential at the point D, but the voltage drop by the ON resistance of the transistor T ₂ occurs. is there. Thus, a current flowing through the base of the transistors T _1, the transistor T ₁ is O
It is possible to prevent it from being N by the resistor R ₉ . As a result, the transistor T ₁ is turned off and the potential at the point E is at the ground level, so that the diode switches D ₁ and D ₂ are in the reverse bias state, and the signal from the transducer Tr ₁ is not supplied to the output point C.

FIG. 3 shows that the inductor L ₁ , the resistor R ₁ , and the capacitor C ₁ on the cathode side of the switching diode D ₁ are combined with the equivalent circuit of the transducer Tr ₁ (the circuit configuration shown in FIG. 3) to match the transmission. Represents the state of functioning as. Since the same applies to the other transducer Tr ₂ , the description thereof will be omitted.

By the above circuit operation, the ultrasonic reception signal obtained at the output point C becomes the state shown in FIG. 4A, and it becomes clear that the mixing of noise can be prevented as compared with the conventional reception signal shown in FIG. 4B.

Modification If the diodes of the diode switches D ₁ , D ₂ , D ₃ , and D ₄ are configured to have high reverse breakdown voltage, reception can be performed on only one side without switching the transmission circuits 5 and 6. Therefore, the transmission selection circuit 7 can be omitted if the mixing of noise is small to some extent.

Further, these transducers may have the same resonance frequency and different focal lengths, or may have the same focal length but different resonance frequencies. Also,
It is also possible to employ those having different resonance frequencies and focal lengths. It is possible to further increase not only two.

The switch SW ₁ for switching the transducer can be provided on the endoscope or the monitor.

〔The invention's effect〕

As described above in detail, according to the present invention, it is possible to prevent the reception signals from being mixed from other than the desired transducer. Further, there is an advantage that the structure of the receiving circuit is simplified and a high-quality image free from noise is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit of an embodiment of the endoscope apparatus of the present invention, FIG. 2 is a circuit diagram showing a circuit of the switch means of FIG. 1, and FIG. 3 is a diode switch and a transducer. Fig. 4 is a circuit diagram showing the matching state of Fig. 4, and Fig. 4 is a received signal waveform diagram according to the related art and the present invention. 1, 2, Tr ₁ , Tr _2, ... Transducer, 3 ... Switching means, 4 ... Receiving amplifier, 5, 6 ... Transmitting circuit, 7 ... Transmission selecting circuit, 8 ... Transducer selecting switch, 9 ... Monitor, D _{1 to} D ₄ ... diode switch, T ₁ ~T ₃ ... switching transistor.

Claims (3)

[Claims] 1. A plurality of transducers having different ultrasonic characteristics provided at a distal end portion of an endoscope, a plurality of transmitting circuits respectively driving the transducers, and operating the transmitting circuit corresponding to a predetermined transducer. Transmitting circuit selecting means, switch means connected to the transducer and configured by a diode switch for selectively switching and outputting a received echo signal from only a predetermined transducer, and a receiving circuit for receiving and amplifying the signal from the switch means. And a selection control means for selectively controlling the switch means and the transmission circuit selection means. Based on the control of the selection control means, switching operation of the switch means and the transmission circuit selection means causes a predetermined transducer to be formed. Activate the corresponding transmitter circuit,
An ultrasonic endoscope apparatus characterized in that only an echo signal received from a predetermined transducer can be received as an output signal. 2. The ultrasonic endoscope apparatus according to claim 1, wherein the switch means is provided in the endoscope. 3. The ultrasonic endoscope apparatus according to claim 1, wherein the switch means is provided in an observation apparatus used in combination with an endoscope.