JP2006346105A - Ultrasonic probe and ultrasonic diagnostic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the precision in measuring the temperature, to reduced the man-hours for attaching a temperature sensor, and to control the cost increase in an ultrasonic probe and an ultrasonic diagnostic apparatus. <P>SOLUTION: The ultrasonic probe comprises a semiconductor substrate 1, a plurality of vibrators 10 formed on the semiconductor substrate 1, and at least one temperature sensor 6 formed on the semiconductor substrate 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ultrasonic probe and an ultrasonic diagnostic apparatus.

  It is useful in various aspects such as safety to detect the surface temperature of the portion that comes into contact with the living body. As the temperature sensor, a thermistor or a thermocouple is generally used, but it is attached to the side surface while avoiding the radiation surface so as not to disturb the sound.

At this mounting location, there is a large error with the temperature of the living body contact portion. Therefore, there is a problem that it is necessary to set the temperature with a margin and the maximum transmission power cannot be input. In addition, there is a problem that the increase in man-hours such as the temperature sensor attachment process and the adhesive management process leads to an increase in cost. Increasing the number of parts such as thermistors can also reduce reliability.
Japanese Patent Laid-Open No. 7-265315

  An object of the present invention is to realize an improvement in temperature measurement accuracy, a reduction in the number of steps for attaching a temperature sensor, and a reduction in cost in an ultrasonic probe and an ultrasonic diagnostic apparatus.

  In one aspect of the present invention, an ultrasonic probe includes a semiconductor substrate, a plurality of vibrators formed on the semiconductor substrate, and at least one temperature sensor formed on the semiconductor substrate.

  According to the present invention, it is possible to improve the accuracy of temperature measurement, reduce the number of steps for attaching the temperature sensor, and suppress the increase in cost.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the present embodiment relates to an ultrasound probe or an ultrasound diagnostic apparatus equipped with the ultrasound probe. As is well known, the ultrasonic diagnostic apparatus has a main function of scanning the inside of a subject with an ultrasonic beam via an ultrasonic probe and generating and displaying an ultrasonic image based on the obtained echo signal.

  The ultrasonic probe according to the present embodiment has a plurality of transducers 10 arranged in a two-dimensional manner. The plurality of vibrators 10 may be arranged one-dimensionally. As shown in FIG. 2, the plurality of vibrators 10 are typically formed on a silicon substrate 1 as a semiconductor substrate by a semiconductor manufacturing process technique. The vibrator 10 is formed on a base electrode (common electrode) 2 formed on the silicon substrate 1, a membrane 4 disposed above the base electrode 2 with a gap 11 having a predetermined thickness, and the membrane 4. It consists of electrodes (individual electrodes) 5. The spacer 3 is provided to secure the gap 11 with a constant thickness, separate the gap 11 for each vibrator 10, and further seal the gap 11 in a vacuum or with a gas. The air gap 11 allows the membrane 4 to vibrate like a drum skin. When a DC voltage (bias voltage) of about 100 to 200 V is applied between the base electrode 2 and the electrode 5 on the membrane 4, the membrane 4 is drawn toward the base electrode 2 by the electrostatic force. When a high voltage is superimposed between the electrodes 2 and 5 in this state, the attracted membrane 4 is displaced according to the change function of the electrostatic force, and is emitted from the membrane 4 as an ultrasonic pulse. On the surface of the membrane 4, a protective film and an acoustic lens (not shown) are disposed on the living body contact surface as necessary, and ultrasonic pulses are emitted to the living body.

  As shown in FIG. 2, a temperature sensor 6 is provided corresponding to at least one vibrator 10. The temperature sensor 6 is formed together with the vibrator 10 in a series of steps for forming the vibrator 10 by semiconductor manufacturing process technology. The temperature sensor 6 may be provided in one specific vibrator 10, may be provided individually in all the vibrators 10, or may be provided in some of the vibrators 10. For example, the temperature sensors 6 are not provided in the eight vibrators 10 around the vibrator 10 provided with the temperature sensors 6. By providing the temperature sensors 6 at a plurality of locations, the temperature distribution on the vibrator surface can be measured, and fine temperature control can be performed.

  The temperature sensor 6 is formed on the silicon substrate 1, in other words, disposed between the silicon substrate 1 and the base electrode 2. The temperature sensor 6 is typically positioned away from the vibration center of the vibrator 10 in order to reduce the influence on vibration, and the temperature sensor 6 has a spacer 3 in order to improve the thermal conductivity from the subject contact portion. Arranged immediately below. Further, in order to improve the detection capability of the heat generation state on the probe side, it is provided at a position immediately above a relatively large portion of heat generation such as a temperature detection circuit 8 and a transmission circuit 9 described later.

  If the temperature sensor 6 is formed on the substrate 1 before forming the vibrator 10 including the membrane 4, the temperature sensor 6 can be embedded under the vibrator 10, and the silicon substrate 1 is not affected by acoustic effects. Temperature can be measured. Since the silicon substrate 1 has high thermal conductivity, it is possible to measure almost the same temperature as the membrane 4 that comes into contact with the living body. A typical diode as the temperature sensor 6 is formed by a normal semiconductor manufacturing process, and then the vibrator 10 including the membrane 4 is formed in order. Therefore, in addition to the diode, the temperature sensor 6 can be formed by a semiconductor manufacturing process, and a bipolar transistor, a MOS transistor, a resistor, or a capacitor can be used as an element whose characteristics change with temperature. In the capacitive vibrator 10 according to the present embodiment, an insulating film or an acoustic lens may be disposed outside the membrane 4, but an acoustic vibrator such as an ultrasonic vibrator using a piezoelectric element may be used. Matching layer is not required and temperature measurement accuracy is high.

  Although the temperature sensor 6 is formed below the vibrator 10 in the above description, the temperature sensor 6 may be arranged in parallel with the membrane 4 on the spacer 3 that supports the membrane 4 when the distance between the adjacent vibrators 10 is relatively long. Thereby, the temperature of a biological contact part can be measured more correctly. Further, if a plurality of elements are arranged in the depth direction or in the horizontal direction, the temperature distribution of the silicon substrate can be measured three-dimensionally.

  As shown in FIG. 3, a temperature detection circuit 8 is connected to the temperature sensor 6. The temperature detection circuit 8 measures the temperature around the temperature sensor 6 by flowing a bias current through the temperature sensor (here, a diode) 6 and observing the voltage change. Actually, since the temperature sensor 6 is very close to the subject contact portion in terms of heat conduction, the temperature around the temperature sensor 6 can be measured as the living body temperature.

  A DC bias voltage is applied to the vibrator 10 from a bias power supply circuit (high voltage power supply) 12. In addition, a transmission circuit 9 is individually connected to the vibrator 10. The transmission circuit 9 generates a high voltage pulse in synchronization with the trigger pulse from the waveform generation / delay control circuit 14. The waveform generation / delay control circuit 14 generates a trigger pulse for each transmission circuit 9 with a delay time corresponding to the depth of focus and the azimuth direction of the ultrasonic scan. A delay data storage unit 15 is connected to the waveform generation / delay control circuit 14. The delay correction data storage unit 15 stores in advance correction data for correcting the delay time for each transducer 10 determined according to the depth of focus and the azimuth direction according to the change in sound velocity due to the change in the living body temperature. . The waveform generation / delay control circuit 14 reads, from the delay correction data storage unit 15, the delay correction data corresponding to the living body temperature based on the signal (biological temperature signal) representing the living body temperature generated from the temperature detecting circuit 8, and the depth of focus and the azimuth. The delay time for each vibrator 10 determined according to the direction is corrected. The waveform generation / delay control circuit 14 individually generates a trigger pulse for each transmission circuit 9 with a time difference corresponding to the corrected delay time.

  As is well known, since the sound speed increases as the temperature increases, the transmission and reception focus are set on the assumption of the sound speed in the living body in which the body temperature is a flat heat such as 37 degrees. For example, a subject with a low body temperature or a subject with a high fever is different from the set sound speed, so that the focus position is shifted. Focusing accuracy can be improved by correction data corresponding to a living body temperature that can be acquired by measurement before transmission and reception. Further, the distance measurement error can be reduced by using the living body temperature even when measuring the distance of the fetal head or the like.

  A signal (biological temperature signal) representing the biological temperature generated from the temperature detection circuit 8 is also supplied to the display control unit 13. The display control unit 13 generates a signal for displaying the living body temperature based on the living body temperature signal as a numerical value or a graphic on a display (not shown), or a signal for turning on the temperature indicator lamp with a color corresponding to the living body temperature. .

  The transmission circuit 9 and the temperature detection circuit 8 are formed on another silicon substrate 7 stacked on the silicon substrate 1 as illustrated in FIG. The transmission circuit 9 and the temperature detection circuit 8 may be formed on the same silicon substrate 1 as the vibrator 10 and the temperature sensor 6.

  In the housing of the ultrasonic probe, together with the ultrasonic transducer 10, the transmission circuit 9, and the temperature detection circuit 8, a reception amplifier (not shown), a bias power supply circuit 12, a waveform generation / delay control circuit 14, and a delay correction data storage unit 15 The display control unit 13 and a display (not shown) are accommodated. In particular, by providing a display on the ultrasound probe, an operator holding the ultrasound probe can easily monitor the living body temperature state and take measures such as separating the ultrasound probe from the subject against excessive temperature rise. Can be done quickly. In addition to the temperature rise due to the body temperature of the living body, the ultrasonic transducer itself generates heat due to multiple reflections with the biological coupling membrane, mechanical loss, loss due to floating impedance, etc. accompanying transmission of ultrasonic waves, As the electronic circuit in the housing, the heat generated by the transmission circuit 9 is mainly transmitted to generate heat. Since heat from the ultrasonic transducer 10 itself and the electronic circuit does not occur unless ultrasonic transmission / reception is started, the temperature of the subject is measured immediately before ultrasonic inspection and before transmission / reception of ultrasonic waves is started. Can be done.

  The temperature detection circuit 8 other than the vibrator 10 and the temperature sensor, the receiving amplifier, the bias power supply circuit 12, the waveform generation / delay control circuit 14, the delay correction data storage unit 15, the display control unit 13, and the display are the ultrasonic probe. In order to suppress heat generation and reduce the weight, the ultrasonic diagnostic apparatus main body may be provided instead of the ultrasonic probe.

  As shown in FIG. 4, the temperature detection circuit 8 can be replaced with a temperature detection circuit 16 having a function of generating a transmission stop signal when the temperature measured by the temperature sensor 6 reaches or exceeds a predetermined threshold. is there. A transmission stop signal from the temperature detection circuit 16 is supplied to the gate circuit 17. The gate circuit 17 is interposed between the waveform generation / delay control circuit 14 and the transmission circuit 9. The gate circuit 17 transmits a trigger pulse from the waveform generation / delay control circuit 14 to the transmission circuit 9 when the transmission stop signal from the temperature detection circuit 16 is not supplied, and when the transmission stop signal is supplied, the transmission circuit 9. A MOS transistor that can be formed by a semiconductor process is typically used to stop transmission of a trigger pulse to the semiconductor device.

  As shown in FIG. 5, the temperature detection circuit 16 extends the drive time by lowering the transmission voltage when the measured temperature reaches or exceeds a threshold temperature lower than the threshold for stopping transmission in FIG. A function for generating a control signal for the power supply circuit 19 of the transmission circuit 9 can be replaced with the temperature detection circuit 18 having the transmission stop function of FIG. The decrease in the transmission voltage is not limited to the decrease in the power supply voltage of the transmission circuit (amplifier) 9 by the power supply circuit 19, but the decrease in the amplification factor of the transmission circuit 9 or the trigger of the waveform generation / delay control circuit 14. You may implement | achieve by the fall of the waveform amplitude of a pulse. Further, the transmission voltage may be changed stepwise using a plurality of threshold values, or may be changed continuously without permission.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

FIG. 3 is a plan view showing a transducer arrangement of an ultrasonic probe in the embodiment of the present invention. Sectional drawing which shows the cross-section of the single vibrator | oscillator of FIG. The figure which shows the peripheral circuit of the element of FIG. 1 in this embodiment. The figure which shows the structure for the transmission stop function accompanying the temperature rise in the modification of this embodiment. The figure which shows the structure for the transmission voltage fall function accompanying a temperature rise in the modification of this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Si substrate, 2 ... Base electrode, 3 ... Spacer, 4 ... Membrane, 5 ... Individual electrode, 6 ... Temperature sensor, 7 ... Si substrate, 8 ... Temperature detection circuit, 9 ... Transmission circuit, 10 ... Vibrator, 12 DESCRIPTION OF SYMBOLS ... Bias power supply circuit, 13 ... Display control circuit, 14 ... Waveform generation / delay control circuit, 15 ... Delay data storage part.

Claims (14)

A semiconductor substrate;
A plurality of vibrators formed on the semiconductor substrate;
An ultrasonic probe comprising: at least one temperature sensor formed on the semiconductor substrate. The ultrasonic probe according to claim 1, wherein the temperature sensor is provided between the semiconductor substrate and the vibrator. The ultrasonic probe according to claim 1, wherein the temperature sensor is provided between the vibrators adjacent to each other. The vibrator includes a base electrode formed on the semiconductor substrate, a membrane disposed on the base electrode with a gap, and generating ultrasonic waves by displacement due to electrostatic force, and an individual electrode formed on the membrane The ultrasonic probe according to claim 1, wherein: The ultrasonic probe according to claim 1, wherein the temperature sensors are discretely arranged. The ultrasonic probe according to claim 1, wherein one temperature sensor is provided for each of the vibrators. The ultrasonic probe according to claim 1, wherein the temperature sensor is a diode, a bipolar transistor, a MOS transistor, or a resistor. The ultrasonic probe according to claim 1, wherein the temperature sensor is provided at a position away from a vibration center of the vibrator. In an ultrasound diagnostic apparatus that transmits and receives ultrasound to and from a subject via an ultrasound probe and generates an ultrasound image based on the obtained echo signal,
The ultrasonic probe includes a semiconductor substrate, a plurality of ultrasonic transducers formed on the semiconductor substrate, and at least one temperature sensor formed on the semiconductor substrate. apparatus. The ultrasonic diagnostic apparatus according to claim 9, further comprising a display control unit that generates a signal for temperature display based on an output of the temperature sensor. The ultrasonic diagnostic apparatus according to claim 9, further comprising a delay control circuit that changes transmission / reception delay control based on an output of the temperature sensor. The ultrasonic diagnostic apparatus according to claim 11, further comprising a storage unit that stores a correspondence relationship between a temperature detected by the temperature sensor and a transmission / reception delay time. The ultrasonic diagnostic apparatus according to claim 9, further comprising a circuit that generates a transmission stop signal based on an output of the temperature sensor. The ultrasonic diagnostic apparatus according to claim 9, further comprising a circuit that generates a signal for changing a transmission voltage based on an output of the temperature sensor.

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