JP2011087628A - Ultrasonic probe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for improving a probe cable of an ultrasonic probe. <P>SOLUTION: An insertion part cable 14 and a connection part cable 16 are composed of, for example, coaxial cables, with different electric characteristics from each other. The resistance of the insertion part cable 14 is larger than that of the connection part cable 16. The characteristic impedance of the connection part cable 16 is larger than that of the insertion part cable 14. Further, the characteristic impedance of the connection part cable 16 is larger than the input impedance of a receiving circuit 22 connected to the connection part cable 16. As a result, excellent transmission characteristics of receiving signals can be acquired while thinning the insertion part cable 14. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ultrasonic probe, and more particularly to a configuration of a probe cable.

  The ultrasonic probe includes a vibration element that transmits and receives an ultrasonic wave and a probe cable, and the probe cable is connected to the main body of the ultrasonic diagnostic apparatus via a connector or the like. A weak ultrasonic wave reception signal obtained from the vibration element is transmitted to a reception circuit in the main body via a probe cable.

  By using a probe cable that is relatively thick and has a small resistance value, attenuation of a weak received signal can be made relatively small. However, if the number of vibrating elements increases and a relatively thick probe cable is used for each vibrating element, the entire probe cable becomes very thick, which is not preferable for a diameter esophageal probe, for example. In addition, when a relatively thin probe cable is used for each vibration element, the resistance value of the probe cable becomes relatively large, and the attenuation of the received signal becomes relatively large.

  Incidentally, Japanese Patent Laid-Open No. 2004-228561 describes a technique for achieving a λ / 4 matching between a piezoelectric vibrator and a receiving circuit using a cable to prevent a decrease in sensitivity of a received signal. However, the technique described in Patent Document 1 does not solve the problem related to the thickness of the cable.

JP-A-6-30934

  In view of the background art described above, the inventor of the present application has conducted research and development on a probe cable of an ultrasonic probe.

  The present invention has been made in the course of research and development, and an object thereof is to provide an improved technique related to a probe cable of an ultrasonic probe.

  An ultrasonic probe suitable for the above-described object includes a vibration element that transmits and receives ultrasonic waves, an insertion portion cable connected to the vibration element, and a connection portion cable connected to the insertion portion cable. The insertion portion cable has a resistance larger than that of the connection portion cable.

  In a preferred embodiment, the connection cable has a characteristic impedance greater than that of the insertion cable.

  In a preferred embodiment, the connection cable has a characteristic impedance larger than an input impedance of a device body connected to the connection cable.

  In a preferred embodiment, the ultrasonic probe is used as a radial esophageal probe by inserting the vibration element and the insertion portion cable into a subject's esophagus.

  According to the present invention, an improved technique related to a probe cable of an ultrasonic probe is provided.

It is a figure which shows the whole structure of the suitable ultrasonic probe in implementation of this invention. It is a figure which shows an example of the electrical property of an insertion part cable and a connection part cable. It is a figure which shows the transmission characteristic of the signal in a probe cable.

  Hereinafter, preferred embodiments of the present invention will be described.

  FIG. 1 is a diagram showing an overall configuration of an ultrasonic probe 10 suitable for implementing the present invention. The ultrasonic probe 10 includes a vibration element 12, an insertion portion cable 14, an operation portion 15, a connection portion cable 16, and a connector 17, and is connected to the main body 20 of the ultrasonic diagnostic apparatus via the connector 17.

  The vibration element 12 transmits and receives ultrasonic waves and outputs a reception signal obtained thereby. The insertion portion cable 14 has one end connected to the vibration element 12 and the other end connected to the operation portion 15. The connection cable 16 has one end connected to the operation unit 15 and the other end connected to the connector 17.

  The insertion portion cable 14 and the connection portion cable 16 are electrically connected to each other within the operation portion 15. The connection cable 16 is electrically connected to the receiving circuit 22 in the main body 20 via the connector 17. Then, the ultrasonic reception signal output from the vibration element 12 is transmitted to the reception circuit 22 via the insertion portion cable 14 and the connection portion cable 16.

  The ultrasonic probe 10 in FIG. 1 is, for example, a diameter esophageal probe, and the examiner examines the vibration element 12 and the insertion portion cable 14 while adjusting the bending state of the insertion portion cable 14 by using the operation portion 15. Into the person's esophagus.

  In the present embodiment, the insertion portion cable 14 and the connection portion cable 16 are both configured as coaxial cables, for example, and have different electrical characteristics. First, the insertion cable 14 has a resistance greater than that of the connection cable 16. Further, the connection cable 16 has a characteristic impedance larger than that of the insertion cable 14. Further, the characteristic impedance of the connection cable 16 is larger than the input impedance of the receiving circuit 22 connected to the connection cable 16.

  Therefore, the electrical characteristics of the ultrasonic probe 10 will be described in detail below. In addition, about the part (structure) already shown in FIG. 1, the code | symbol of FIG. 1 is utilized also in the following description.

  FIG. 2 is a diagram illustrating an example of electrical characteristics of the insertion portion cable 14 and the connection portion cable 16. For example, the insertion cable 14 has a length of 1 m, a resistance value of a unit length (1 m) is 60Ω, an inductance of the unit length is 0.34 μH, and a capacitance of the unit length is 95 pF. . On the other hand, the connection cable 16 has, for example, a length of 2 m, a resistance value of a unit length (1 m) of 5Ω, an inductance of a unit length of 0.34 μH, and a capacitance of a unit length of 65 pF. It is.

  In FIG. 2, the electrical characteristics of the vibration element 12 are simulated by the voltage source V1 and the resistor R1. The resistor R1 is, for example, 1 kΩ. Further, the input impedance of the receiving circuit 22 is simulated by the resistor R2. The resistor R2 is, for example, 60Ω.

  The transmission characteristics of signals transmitted from the input terminal IN to the output terminal OUT in the electrical characteristic path shown in FIG. 2 are as follows.

  FIG. 3 is a diagram illustrating signal transmission characteristics in the probe cable. The horizontal axis in FIG. 3 represents the frequency of the transmitted signal, and the vertical axis in FIG. 3 represents the attenuation of the transmitted signal. . The attenuation on the vertical axis is a relative value with the low frequency part of the characteristic 102 as a reference.

  A characteristic 100 in FIG. 3 indicates a transmission characteristic of a signal transmitted from the input terminal IN to the output terminal OUT in FIG. 2, that is, a transmission characteristic of a reception signal of the ultrasonic probe 10 in FIG. The characteristic 100 shown in FIG. 3 is a flat characteristic with almost no attenuation from a low frequency to about 10 MHz. Therefore, for example, when the vibration element 12 is driven by a transmission signal having a frequency of about 5 MHz to obtain an ultrasonic reception signal (fundamental wave), the reception signal is transmitted to the reception circuit 22 with almost no attenuation. Can do.

  In FIG. 3, as a comparative example for the characteristic 100 according to the present embodiment, other characteristics are indicated by broken lines.

  A characteristic 102 is a transmission characteristic when one thick coaxial cable having a resistance value of 5Ω is used instead of the insertion section cable 14 and the connection section cable 16. Since the resistance value is small, the characteristic 102 is less attenuated even at a high frequency exceeding 10 MHz. However, since a thick cable is used to reduce the resistance value, if the number of vibrating elements is large, the entire probe cable becomes very thick, which is not preferable for a diameter esophageal probe, for example. On the other hand, in this embodiment, since the resistance value of the insertion portion cable 14 may be large, a thin coaxial cable can be used as the insertion portion cable 14, and the entire probe cable can be used even when a large number of vibration elements are used. Can be made relatively thin.

  In the present embodiment, when viewed from the vibration element 12 side, the insertion portion cable 14 is terminated with a characteristic impedance of the connection portion cable 16 that is larger than the characteristic impedance of the insertion portion cable 14, and thus looks like a capacitor. The connection cable 16 is terminated with an input impedance of the receiving circuit 22 smaller than the characteristic impedance of the connection cable 16 and thus looks like an inductor. Due to the resonant action of these capacitors and inductors, a frequency characteristic that is relatively flat and less attenuated can be obtained as shown by characteristic 100 in FIG. 3 without matching the characteristic impedance.

  Incidentally, the characteristic 104 is a transmission characteristic when the characteristic impedances of the insertion cable 14 and the connection cable 16 are matched. For example, the attenuation of the characteristic 104 is larger than that of the characteristic 100 in the vicinity of the frequency of 10 MHz.

  The characteristic 106 is a transmission characteristic in the case where one thin coaxial cable having a resistance value of 60Ω is used instead of the insertion cable 14 and the connection cable 16. Since the resistance value is large, the attenuation is relatively large even in the low range, and the attenuation in the high range is also very large.

  The preferred embodiment of the present invention has been described above. However, according to the above-described embodiment, it is possible to obtain good transmission characteristics of the received signal while making the insertion cable 14 thinner.

  The above-described embodiments are merely examples in all respects, and do not limit the scope of the present invention. The present invention includes various modifications without departing from the essence thereof. For example, an amplifier may be inserted between the vibration element 12 and the insertion portion cable 14, and the insertion portion cable 14 may be connected to the vibration element 12 via the amplifier.

  DESCRIPTION OF SYMBOLS 10 Ultrasonic probe, 12 Vibration element, 14 Insertion part cable, 15 Operation part, 16 Connection part cable, 17 Connector.

Claims (4)

A vibration element for transmitting and receiving ultrasonic waves;
An insertion portion cable connected to the vibration element;
A connection cable connected to the insertion cable;
Have
The insertion portion cable has a resistance greater than that of the connection portion cable.
An ultrasonic probe characterized by that. The ultrasonic probe according to claim 1,
The connection cable has a characteristic impedance greater than that of the insertion cable,
An ultrasonic probe characterized by that. The ultrasonic probe according to claim 2,
The connection cable has a characteristic impedance larger than the input impedance of the apparatus main body connected to the connection cable.
An ultrasonic probe characterized by that. The ultrasonic probe according to any one of claims 1 to 3,
The vibration element and the insertion portion cable are inserted into a subject's esophagus and used as a radial esophageal probe,
An ultrasonic probe characterized by that.

Images