Ultrasonic transducer, ultrasonic probe, diagnostic device, and electronic instrument

An ultrasonic transducer includes “m” first ultrasonic elements including first diaphragms, and “n” second ultrasonic elements including second diaphragms. “m” represents a number of the first ultrasonic elements and is an integer of 1 or more. Each of the first diaphragms has a first area. “n” second ultrasonic elements includes second diaphragms. Each of the “n” second diaphragms has a second area being smaller than the first area. “n” represents a number of the second ultrasonic elements and is an integer larger than “m”. The “m” first ultrasonic elements are electrically connected in series in a case where “m” is an integer of 2 or more. The “n” second ultrasonic elements are electrically connected in series. B/A is within a range of 0.9 to 1.1, when a total sum of the first areas is “A” and a total sum of the second areas is “B”.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No. 2012-115321 filed on May 21, 2012. The entire disclosure of Japanese Patent Application No. 2012-115321 is hereby incorporated herein by reference.

BACKGROUND

1. Technical Field

The present invention relates to an ultrasonic transducer, an ultrasonic probe, a diagnostic device, and an electronic instrument.

2. Background Technology

An ultrasonic transducer in which a plurality of ultrasonic elements are arranged in a matrix pattern has been known. This ultrasonic transducer includes a substrate that has a plurality of openings, a supporting film that is provided on the substrate so as to cover each of the openings, and a piezoelectric element that is provided on a part of the supporting film corresponding to each of the openings. A diaphragm is constructed by the part of the supporting film corresponding to the opening which is a part coinciding with the opening of the supporting film in a planar view. The ultrasonic element is constructed by the diaphragm and the piezoelectric element provided on the diaphragm.

In this ultrasonic transducer, it has been known that two kinds of ultrasonic elements in which the areas of the diaphragms are different are provided, and are driven at different frequencies (for example, see Patent Document 1). In Patent Document 1, it is considered that the plurality of ultrasonic elements having the larger areas of the diaphragms are electrically connected in parallel with respect to each other. Likewise, it is considered that the plurality of ultrasonic elements having the smaller areas of the diaphragms are electrically connected in parallel with respect to each other.

When the two kinds of ultrasonic elements are compared, since the ultrasonic elements having the larger areas of the diaphragms have low resonance frequency, they are driven at low frequency and generate ultrasonic waves of low frequency. Also, since the ultrasonic elements having the smaller areas of the diaphragms have high resonance frequency, they are driven at high frequency and generate ultrasonic waves of high frequency. In a diagnostic device having an ultrasonic probe that uses this ultrasonic transducer, when a deep part (long distance) of a living body as a test target is diagnosed, ultrasonic waves of low frequency are used for diagnosis because ultrasonic waves of high frequency cannot reach a deep part. On the other hand, when a shallow part (short distance) of a living body is diagnosed, ultrasonic waves of high frequency are used for diagnosis so as to increase the resolution.

However, the sensitivity of an ultrasonic element becomes high as the area of the diaphragm becomes large. Therefore, the well-known ultrasonic transducer has a problem that the sensitivity of the ultrasonic elements having the smaller areas of the diaphragms is lower than that of the ultrasonic elements having the larger areas of the diaphragms. Further, due to the difference in the sensitivity, there is a problem that the magnitude of a signal output from each ultrasonic element is different, and a circuit configuration becomes complicated in order to match the magnitude of the signal.

Japanese Laid-open Patent Publication No. 2006-75425 (Patent Document 1) is an example of the related art.

SUMMARY

Problems to be Solved by the Invention

The advantage of the invention is to provide an ultrasonic transducer, an ultrasonic probe, a diagnostic device, and an electronic instrument in which the difference in the sensitivity between two kinds of ultrasonic element groups is reduced, ultrasonic waves of a plurality of frequencies can be transmitted and received, and also the circuit configuration can be simplified.

Means Used to Solve the Above-Mentioned Problems

This advantage is achieved by the invention described below. According to one aspect of the invention, an ultrasonic transducer of the invention includes “m” first ultrasonic elements and “n” second ultrasonic elements. The “m” first ultrasonic elements includes first diaphragms. The “m” first ultrasonic elements are configured and arranged to transmit and receive ultrasonic waves, where “m” represents a number of the first ultrasonic elements and is an integer of 1 or more. Each of the first diaphragms having a first area. The “n” second ultrasonic elements include second diaphragms. Each of the “n” second diaphragms has a second area being smaller than the first area. The “n” second ultrasonic elements are configured and arranged to transmit and receive the ultrasonic waves, where “n” represents a number of the second ultrasonic elements and is an integer larger than “m”. The “m” first ultrasonic elements are electrically connected in series in a case where “m” is an integer of 2 or more. The “n” second ultrasonic elements are electrically connected in series. B/A is within a range of 0.9 to 1.1, when a total sum of the first areas is “A” and a total sum of the second areas is “B”.

According to another aspect of the invention, an ultrasonic transducer includes a plurality of ultrasonic elements being arranged on the ultrasonic transducer with predetermined intervals. The plurality of ultrasonic elements include “m” first ultrasonic elements and “n” second ultrasonic elements. The “m” first ultrasonic elements include first diaphragms. The “m” first ultrasonic elements are configured and arranged to transmit and receive ultrasonic waves, where “m” represents the number of the first ultrasonic elements and is an integer of 1 or more. Each of the first diaphragms has a first area. The “n” second ultrasonic elements include second diaphragms. Each of the “n” second diaphragms has a second area being smaller than the first area. The “n” second ultrasonic elements are configured and arranged to transmit and receive the ultrasonic waves, where “n” representing the number of the second ultrasonic elements and is an integer larger than “m”. The “m” first ultrasonic elements are electrically connected in series in a case where “m” is an integer of 2 or more. The “n” second ultrasonic elements are electrically connected in series. B/A is within a range of 0.9 to 1.1, when a total sum of the first areas is “A” and a total sum of the second areas is “B”.

According to another aspect of the invention, an ultrasonic transducer includes a substrate, a supporting film, and a piezoelectric body. The substrate includes a plurality of openings. The supporting film is configured to cover the plurality of openings. The piezoelectric body is configured on the supporting film at one of the plurality of openings. The plurality of openings include “m” first openings, where “m” represents a number of the first openings and is an integer of 1 or more. Each of the first openings has a first opening area covered with the supporting film on a surface of the substrate. The plurality of openings include “n” second openings, where “n” represents a number of the second openings and is an integer larger than “m”. Each of the second openings has a second opening area that is smaller than the first area. “m” first piezoelectric bodies, which are formed corresponding to the “m” first openings, of the piezoelectric body are electrically connected in series in a case where “m” is an integer of 2 or more. “n” second piezoelectric bodies, which are formed corresponding to the “n” second openings, of the piezoelectric body are electrically connected in series. B/A is within the range of 0.9 to 1.1, when a total sum of the first opening areas is “A” and a total sum of the second opening areas is “B”.

According to another aspect of the invention, an ultrasonic transducer includes a substrate, a supporting film, and a piezoelectric body. The substrate includes a plurality of openings. The supporting film is configured to cover the plurality of openings. The piezoelectric body is configured on the supporting film at one of the plurality of openings. The plurality of openings include an arrangement opening group with predetermined intervals. The opening group include “m” first openings, where “m” represents a number of the first openings and is an integer of 1 or more. Each of the “m” first openings has a first opening area covered with the supporting film on a surface of the substrate. The opening group includes “n” second openings, where “n” represents a number of the second openings and is an integer larger than “m”. Each of the “n” second openings has a second opening area that is smaller than the first area. “m” first piezoelectric bodies, which are formed corresponding to the “m” first openings, of the piezoelectric body are electrically connected in series in a case where “m” is an integer of 2 or more. “n” second piezoelectric bodies, which are formed corresponding to the “n” second openings, of the piezoelectric body are electrically connected in series. B/A is within the range of 0.9 to 1.1, when a total sum of the first areas is “A” and a total sum of the second areas is “B”

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, the ultrasonic transducer, the ultrasonic probe, the diagnostic device, and the electronic instrument of the invention will be explained in detail based on a preferred embodiment shown in the attached drawings.

Embodiment of Ultrasonic Transducer and Ultrasonic Probe

FIG. 1is a perspective view showing an embodiment of the ultrasonic probe according to the invention.FIG. 2is a plan view showing the ultrasonic transducer of the ultrasonic probe shown inFIG. 1.FIG. 3is a plan view showing a cell unit of the ultrasonic transducer shown inFIG. 2.FIG. 4is a plan view enlarging a part of the ultrasonic transducer shown inFIG. 2.FIG. 5is a sectional view along line A-A ofFIG. 4.

Hereinafter, explanations will be made by describing the upper side inFIG. 2-FIG. 5as “upper”, the lower side as “lower”, the right side as “right”, and the left side as “left”. InFIG. 2andFIG. 3, illustrations of parts and the like of an acoustic matching section, an upper electrode, a lower electrode, a conducting wire for an upper electrode, and a conducting wire for a lower electrode are omitted, and the ultrasonic transducer is schematically illustrated. Further, inFIG. 2andFIG. 3, the outline of the cell unit is shown by a broken line. InFIG. 4, an illustration of the acoustic matching section is omitted. Also, as shown in each drawing, an X axis and a Y axis orthogonal to each other are assumed. An X axis direction corresponds to an azimuth direction, and a Y axis direction corresponds to a slice direction.

As shown inFIG. 1, an ultrasonic probe10has a case200, and an ultrasonic transducer1that is housed (accommodated) in the case200. The ultrasonic transducer1is disposed in a tip end portion (the lower side in the drawing) of the case200. In such a case, a substrate2, described below, of the ultrasonic transducer1is fixed to the case200directly or with a supporting member for supporting the substrate2. The supporting member is not shown in the drawing. The ultrasonic probe10can be used as an ultrasonic probe for various kinds of diagnostic devices such as a diagnostic device100described below.

In the present embodiment, a surface of the ultrasonic transducer1, that is, a surface of an acoustic matching section6is exposed outside. The acoustic matching section6serves as a protective layer of the ultrasonic probe10and the ultrasonic transducer1. Although the constituent material of the acoustic matching section6is not limited to a specific one, a material that is substantially similar to a living body with respect to the acoustic impedance, such as silicone rubber, is used. Here, it may be configured such that the surface of the acoustic matching section6is not exposed outside.

In the present embodiment, the ultrasonic probe10is a contact type sensor that is used by bringing the surface of the acoustic matching section6into contact with (applying to) a living body as a test target. Specifically, in conducting a test, the ultrasonic probe10is used by applying the surface of the acoustic matching section6to a living body as a test target. In such a case, when ultrasonic waves are sent out from an ultrasonic element, described below, of the ultrasonic transducer1toward the acoustic matching section6, the ultrasonic waves pass through the acoustic matching section6and propagate through the living body. Then, the ultrasonic waves reflected on a predetermined part inside the living body pass through the acoustic matching section6and are input to the ultrasonic element.

Also, the ultrasonic probe10is electrically connected with a device main body300(seeFIG. 6andFIG. 7), described below, of the diagnostic device100through a cable210. As shown inFIG. 2-FIG. 5, the ultrasonic transducer1has the substrate2, a plurality of (nine in the configuration shown in the drawing) cell units (ultrasonic element units)4that are provided on the substrate2so as to transmit and receive ultrasonic waves, and the acoustic matching section6that is provided on the substrate2on the side of the cell units4so as to cover each of the cell units4.

Although the shape of the substrate2is not limited to a specific one, it forms a quadrangle in a planar view (in a planar view seen from the thickness direction of the substrate2) in the configuration shown in the drawing. Also, as another shape of the substrate2in a planar view, another polygon such as a pentagon or a hexagon, a circle, or an ellipse can be listed, for example. Although the constituent material of the substrate2is not limited to a specific one, a material for forming a semiconductor such as silicon (Si) is used, for example. Consequently, it can be processed easily by etching or the like. Each cell unit4is arranged on the substrate2in a matrix pattern, that is, in a two-dimensionally pattern with predetermined intervals. In other words, a plurality of (three in the configuration shown in the drawing) cell units4are arranged in parallel along the X axis direction, and a plurality of (three in the configuration shown in the drawing) cell units4are arranged in parallel along the Y axis direction.

The cell unit4has a first ultrasonic element group3aprovided with “m” first ultrasonic elements (first ultrasonic vibrators)8a, with “m” representing the number of the first ultrasonic elements and being an integer of 1 or more (one in the configuration shown in the drawing), that have first diaphragms51a, and transmit and receive ultrasonic waves, a second ultrasonic element group3bprovided with “n” second ultrasonic elements (second ultrasonic vibrators)8b, with “n” representing the number of the second ultrasonic elements and being an integer larger than “m” (four in the configuration shown in the drawing), that have second diaphragms51bwhose areas (areas in a planar view) are smaller than those of the first diaphragms51a, and transmit and receive ultrasonic waves, and two third ultrasonic element groups3cand3dprovided with “k” third ultrasonic elements (third ultrasonic vibrators)8c,8d, with “k” representing the number of the third ultrasonic elements and being an integer larger than “m” (nine in the configuration shown in the drawing), that have third diaphragms51cand51dwhose areas (areas in a planar view) are smaller than those of the second diaphragms51b, respectively, and transmit and receive ultrasonic waves. However, the number of the third ultrasonic element groups may be one.

Hereinafter, the first ultrasonic element group3a, the second ultrasonic element group3b, and the third ultrasonic element groups3cand3dare also referred to as “ultrasonic element group”, respectively. Further, the first ultrasonic element8a, the second ultrasonic element8b, and the third ultrasonic elements8cand8dare also referred to as “ultrasonic element”, respectively. Further, the first diaphragm51a, the second diaphragm51b, and the third diaphragms51cand51dare also referred to as “diaphragm”, respectively.

The first ultrasonic element group3ais disposed at the upper left, the second ultrasonic element group3bis disposed at the lower right, the third ultrasonic element group3cis disposed at the upper right, and the third ultrasonic element group3dis disposed at the lower left, respectively. However, needless to say, the invention is not limited to this arrangement. Here, explanations will be made on the first ultrasonic element8a, the second ultrasonic element8b, and the third ultrasonic elements8cand8dHowever, these ultrasonic elements8a,8b,8c, and8dhave similar basic configurations although the sizes are different. Hereinafter, therefore, explanations will be made on the first ultrasonic element8aas a representative. InFIG. 4andFIG. 5, for the second ultrasonic element group3band the third ultrasonic element groups3cand3d, each section thereof that corresponds to each section of the first ultrasonic element group3ais shown with a reference symbol “b”, “c” or “d” instead of “a” at the end thereof with parenthesis.

As shown inFIG. 4andFIG. 5, the first ultrasonic element8ais constructed by the first diaphragm51aand a piezoelectric body (piezoelectric element)7a. The first ultrasonic element8ais formed on the substrate2. Although the shape of the piezoelectric body7ais not limited to a specific one, it forms a circle in a planar view in the configuration shown in the drawing. Also, as another shape of the piezoelectric body7ain a planar view, a quadrangle (square, rectangle), a polygon such as a pentagon or a hexagon, or an ellipse can be listed, for example. Incidentally, the piezoelectric body7aand the wiring thereof will be described below. An opening21for forming the first diaphragm51aof the first ultrasonic element8ais formed in a part of the substrate2corresponding to each of the first ultrasonic element8a. Although the shape of the opening21is not limited to a specific one, it forms a circle in a planar view in the configuration shown in the drawing. Also, as another shape of the opening21in a planar view, a quadrangle (square, rectangle), a polygon such as a pentagon or a hexagon, or an ellipse can be listed, for example.

A supporting film5is formed on the substrate2, and each of the openings21is covered with the supporting film5. The first diaphragm51ais constructed by a part of the supporting film5corresponding to the opening which is a part (region) covering the opening21, that is, a part coinciding with (part overlapping with) the opening21of the supporting film5in a planar view. The piezoelectric body7ais provided on the first diaphragm51a.

Although the constituent material of the supporting film5is not limited to a specific one, the supporting film5is constructed by a layered body (two-layer structure) of an SiO2layer and a ZrO2layer, or an SiO2layer, for example. In a case where the substrate2is an Si substrate, the SiO2layer can be formed by conducting a thermal oxidation treatment to the surface of the substrate2. The ZrO2layer can be formed on the SiO2layer, for example, by a technique such as sputtering. Here, the ZrO2layer is a layer for preventing Pb that constitutes PZT from diffusing into the SiO2layer when PZT is used as a piezoelectric film72aof the piezoelectric body7a, for example. The piezoelectric film72aof the piezoelectric body7awill be described below. The ZrO2layer also has an effect such as an effect of improving deflection efficiency with respect to deformation of the piezoelectric film72a.

As shown inFIG. 5, the piezoelectric body7ahas a lower electrode71aformed on the first diaphragm51a(the supporting film5), the piezoelectric film72aformed on the lower electrode71a, and an upper electrode73aformed on the piezoelectric film72a. Also, a conducting wire (wiring) for a lower electrode711ais connected with the lower electrode71a, and the conducting wire for a lower electrode711aextends along the Y axis direction on the supporting film5as shown inFIG. 4, for example. The conducting wire for a lower electrode711ais electrically connected with the cable210via a through-hole formed in the supporting film5and the substrate2. The through-hole is not shown in the drawing. With this configuration, the first ultrasonic element8a(the first ultrasonic element group3a) can be driven independently. Likewise, the second ultrasonic element group3band the third ultrasonic element groups3cand3dcan be driven independently.

In the second ultrasonic element group3b, each second ultrasonic element8bis electrically connected in series by a conducting wire for a lower electrode711b. In this case, the conducting wire for a lower electrode711bis interposed between lower electrodes71bof two adjacent second ultrasonic elements8b, and the lower electrodes71bof the two adjacent second ultrasonic elements8bare electrically connected by the conducting wire for a lower electrode711b.

Likewise, in the third ultrasonic element group3c, each third ultrasonic element8cis electrically connected in series by a conducting wire for a lower electrode711c. In this case, the conducting wire for a lower electrode711cis interposed between lower electrodes71cof two adjacent third ultrasonic elements8c, and the lower electrodes71cof the two adjacent third ultrasonic elements8care electrically connected by the conducting wire for a lower electrode711c.

Likewise, in the third ultrasonic element group3d, each third ultrasonic element8dis electrically connected in series by a conducting wire for a lower electrode711d. In this case, the conducting wire for a lower electrode711dis interposed between lower electrodes71dof two adjacent third ultrasonic elements8d, and the lower electrodes71dof the two adjacent third ultrasonic elements8dare electrically connected by the conducting wire for a lower electrode711d.

As shown inFIG. 4andFIG. 5, for example, a conducting wire (wiring) for an upper electrode731ais connected with the upper electrodes73a,73b,73cand73d, and the conducting wire for an upper electrode731aextends along the X axis direction on the supporting film5. The conducting wire for an upper electrode731aserves as a common conducting wire of each first ultrasonic element8a(the first ultrasonic element group3a), the second ultrasonic element group3b, the third ultrasonic element group3c, and the third ultrasonic element group3darranged in the X axis direction, and is connected to the GND, for example, at the end portion thereof. In this manner, the upper electrodes73a,73b,73cand73dof the ultrasonic element8a,8b,8cand8dare earthed. Alternatively, contrary to the above, the conducting wires for a lower electrode711a,711b,711c, and711dmay be connected to the GND.

The constituent materials of the lower electrode71a, the upper electrode73a, the conducting wire for a lower electrode711a, and the conducting wire for an upper electrode731aare not limited to specific ones as long as they have conductive properties, respectively. For example, various kinds of metal materials can be used. Also, the lower electrode71a, the upper electrode73a, the conducting wire for a lower electrode711a, and the conducting wire for an upper electrode731amay be single layers, respectively, or may be layered bodies in which a plurality of layers are laminated, respectively. As specific examples, for example, a Ti/Ir/Pt/Ti layered film can be used as the lower electrode71aand the conducting wire for a lower electrode711a, respectively, and an Ir film can be used as the upper electrode73aand the conducting wire for an upper electrode731a, respectively.

The piezoelectric film72ais made by forming PZT (lead zirconate titanate) into a film shape, for example. In the present embodiment, PZT is used as the piezoelectric film72a. However, any material can be used as long as it is a material that can contract (expand or contract) in an in-plane direction by applying a voltage thereto. For example, lead titanate (PbTiO3), lead zirconate (PbZrO3), lead lanthanum titanate ((Pb, La) TiO3), or the like can be used as well as PZT.

In the first ultrasonic element8a, for example, when a voltage is applied between the lower electrode71aand the upper electrode73aby the device main body300(seeFIG. 6,FIG. 7) through the cable210, the piezoelectric film72aexpands or contracts in the in-plane direction. In this instance, a surface of the piezoelectric film72ais attached to the supporting film5through the lower electrode71a, and the upper electrode73ais formed on the other surface thereof. Here, since any other layer is not formed on the upper electrode73a, the supporting film5side of the piezoelectric film72adoes not easily expand or contract, while the upper electrode73aside of the piezoelectric film72aeasily expands or contracts. Therefore, when a voltage is applied to the piezoelectric film72a, deflection that causes projection occurs on the opening21side, which results in deflection of the first diaphragm51a. Consequently, when an alternating voltage is applied to the piezoelectric film72a, the first diaphragm51avibrates with respect to the film thickness direction, and this vibration of the first diaphragm51atransmits (sends) ultrasonic waves.

In transmission of such ultrasonic waves, an alternating voltage, whose frequency is equal to the resonance frequency of the first ultrasonic element8a, or is close to the resonance frequency and is smaller than the resonance frequency, is applied to the piezoelectric film72a, and the first ultrasonic element8ais resonantly driven. With this, the first diaphragm51ais greatly deflected, so that ultrasonic waves can be transmitted with high output. Preferably, in this case, the frequency of the alternating voltage applied to the first ultrasonic element8ais between 0.5 times and 0.9 times with respect to the resonance frequency of the first ultrasonic element8a. If the frequency of the alternating voltage is less than 0.5 times with respect to the resonance frequency of the first ultrasonic element8a, the output of the transmitted ultrasonic waves will become small and the waveform of the ultrasonic waves will easily be disturbed depending on other conditions. On the other hand, if the frequency of the alternating voltage is more than 0.9 times with respect to the resonance frequency of the first ultrasonic element8a, the first ultrasonic element8awill easily be damaged depending on other conditions.

In receiving ultrasonic waves with the first ultrasonic element8a, when ultrasonic waves are input to the first diaphragm51a, the first diaphragm51avibrates with respect to the film thickness direction. In the first ultrasonic element8a, this vibration of the first diaphragm51acauses a potential difference between the surface of the piezoelectric film72aon the lower electrode71aside and the surface of the piezoelectric film72aon the upper electrode73a, and a reception signal (detection signal) (current) is output from the upper electrode73aand the lower electrode71ain response to the displacement amount of the piezoelectric film72a. This signal is transmitted to the device main body300(seeFIG. 6,FIG. 7) through the cable210, and predetermined signal processing or the like is conducted based on the signal. Then, in the device main body300, an ultrasonic image (electronic image) is formed and displayed.

In the ultrasonic probe10, planar waves of ultrasonic waves can be transmitted in a desired direction by delaying and differentiating the timing of transmission of ultrasonic waves from each cell unit4arranged in parallel along the X axis direction. Here, when the area of the first diaphragm51aof the first ultrasonic element8ais “S1”, the area of the second diaphragm51bof the second ultrasonic element8bis “S2”, and the area of the third diaphragms51c,51dof the third ultrasonic elements8c,8dis “S3”, it is sufficient for them to satisfy S1>S2>S3. Preferably, however, S2/S1 is within the range of 0.2 to 0.8, and more preferably, S2/S1 is within the range of 0.3 to 0.6. Also, preferably, S3/S1 is within the range of 0.1 to 0.5, and more preferably, S3/S1 is within the range of 0.2 to 0.4.

Also, when the resonance frequency of the first ultrasonic element8ais “F1”, the resonance frequency of the second ultrasonic element8bis “F2”, and the resonance frequency of the third ultrasonic elements8c,8dis “F3” (F1<F2<F3), it is preferable to set S1, S2, and S3, respectively, such that F3 becomes the least common multiple of F1 and F2. The number of the second ultrasonic element8bof the second ultrasonic element group3bis greater than the number of the first ultrasonic element8aof the first ultrasonic element group3a. In the present embodiment, the second ultrasonic element group3bhas three or more second ultrasonic elements8b, and more specifically, the second ultrasonic element group3bhas four second ultrasonic elements8b.

The numbers of the third ultrasonic elements8c,8dof the third ultrasonic element groups3c,3dare greater than the number of the second ultrasonic element8bof the second ultrasonic element group3b, respectively. In the present embodiment, the third ultrasonic element groups3c,3dhave four or more third ultrasonic elements8c,8d, and more specifically, the third ultrasonic element groups3c,3dhave nine third ultrasonic elements8c,8d, respectively. Here, the number of the second ultrasonic element8bof the second ultrasonic element group3bis not limited to a specific one as long as it is greater than the number of the first ultrasonic element8aof the first ultrasonic element group3a. Preferably, however, the number of the second ultrasonic element8bof the second ultrasonic element group3bis between 4 and 6.

The numbers of the third ultrasonic elements8c,8dof the third ultrasonic element groups3c,3dare not limited to specific ones as long as they are greater than the number of the second ultrasonic element8bof the second ultrasonic element group3b, respectively. Preferably, however, the numbers of the third ultrasonic elements8c,8dof the third ultrasonic element groups3c,3dare between 5 to 10. When the total sum of the areas of the first diaphragms51aof the first ultrasonic element group3ais “A” and the total sum of the areas of the second diaphragms51bof the second ultrasonic element group3bis “B”, B/A is within the range of 0.9 to 1.1. With this configuration, since the sensitivity of the first ultrasonic element8adepends on the area of the first diaphragm51a, the sensitivity of the first ultrasonic element group3aand the sensitivity of the second ultrasonic element group3bcan be made substantially the same. Consequently, a circuit needed for matching the magnitude of a signal in a case where the sensitivity is different can be omitted, and thus the circuit configuration can be simplified.

Preferably, B/A is within the range of 0.95 to 1.05. In this case, since the difference between the noise level of the first ultrasonic element group3aand the noise level of the second ultrasonic element group3bis small, there is no need to conduct fine adjustment so as to compare each signal when displaying a tomographic image. Therefore, the circuit configuration can further be simplified. When the total sum of the areas of the third diaphragms51c,51dof the third ultrasonic element groups3c,3dis “C”, C/A is within the range of 0.9 to 1.1. With this configuration, the sensitivity of the first ultrasonic element group3aand the sensitivity of the third ultrasonic element groups3c,3dcan be made substantially the same. Consequently, a circuit needed for matching the magnitude of a signal in a case where the sensitivity is different can be omitted, and thus the circuit configuration can be simplified.

Preferably, C/A is within the range of 0.95 to 1.05. In this case, since the difference between the noise level of the first ultrasonic element group3aand the noise level of the third ultrasonic element group3cis small, there is no need to conduct fine adjustment so as to compare each signal when displaying a tomographic image. Therefore, the circuit configuration can further be simplified. Also, preferably, the conducting wire for a lower electrode711bthat is a wiring for electrically connecting each second ultrasonic element8bof the second ultrasonic element group3bin series is provided such that the total sum of distances Lb of the conducting wires for a lower electrode711bbetween two adjacent second ultrasonic elements8bwhich are electrically connected with each other becomes shortest. With this configuration, the voltage drop in the conducting wire for a lower electrode711bcan be reduced.

In the present embodiment, each second ultrasonic element8bof the second ultrasonic element group3bis connected by the conducting wire for a lower electrode711bas shown inFIG. 3. This configuration meets the conditions that the total sum of the distances Lb is shortest. Likewise, preferably, the conducting wire for a lower electrode711cthat is a wiring for electrically connecting each third ultrasonic element8cof the third ultrasonic element group3cin series is provided such that the total sum of distances Lc of the conducting wires for a lower electrode711cbetween two adjacent third ultrasonic elements8cwhich are electrically connected with each other becomes shortest. With this configuration, the voltage drop in the conducting wire for a lower electrode711ccan be reduced.

In the present embodiment, each third ultrasonic element8cof the third ultrasonic element group3cis connected by the conducting wire for a lower electrode711cin a zigzag pattern as shown inFIG. 3. This configuration meets the conditions that the total sum of the distances Lc is shortest. Likewise, preferably, the conducting wire for a lower electrode711dthat is a wiring for electrically connecting each third ultrasonic element8dof the third ultrasonic element group3din series is provided such that the total sum of distances Ld of the conducting wires for a lower electrode711dbetween two adjacent third ultrasonic elements8dwhich are electrically connected with each other becomes shortest. With this configuration, the voltage drop in the conducting wire for a lower electrode711dcan be reduced.

In the present embodiment, each third ultrasonic element8dof the third ultrasonic element group3dis connected by the conducting wire for a lower electrode711din a zigzag pattern as shown inFIG. 3. This configuration meets the conditions that the total sum of the distances Ld is shortest. Here, as the pattern of the conducting wire for a lower electrode711c,711dthat makes the total sum of the distances Lc or Ld shortest, a spiral pattern can be listed, for example, as well as the above pattern.

Preferably, in the conducting wire for a lower electrode711bthat is a wiring for electrically connecting each second ultrasonic element8bof the second ultrasonic element group3bin series, all of the distances Lb of the conducting wires for a lower electrode711bbetween two adjacent second ultrasonic elements8bof the second ultrasonic element group3bwhich are electrically connected with each other are the same. With this configuration, the phase difference of ultrasonic waves between two adjacent second ultrasonic elements8bwhich are electrically connected with each other can be made the same in the second ultrasonic element group3b, and thus designing can be conducted easily.

Likewise, preferably, in the conducting wire for a lower electrode711cthat is a wiring for electrically connecting each third ultrasonic element8cof the third ultrasonic element group3cin series, all of the distances Lc of the conducting wires for a lower electrode711cbetween two adjacent third ultrasonic elements8cof the third ultrasonic element group3cwhich are electrically connected with each other are the same. With this configuration, the phase difference of ultrasonic waves between two adjacent third ultrasonic elements8cwhich are electrically connected with each other can be made the same in the third ultrasonic element group3c, and thus designing can be conducted easily.

Likewise, preferably, in the conducting wire for a lower electrode711dthat is a wiring for electrically connecting each third ultrasonic element8dof the third ultrasonic element group3din series, all of the distances Ld of the conducting wires for a lower electrode711dbetween two adjacent third ultrasonic elements8dof the third ultrasonic element group3dwhich are electrically connected with each other are the same. With this configuration, the phase difference of ultrasonic waves between two adjacent third ultrasonic elements8dwhich are electrically connected with each other can be made the same in the third ultrasonic element group3d, and thus designing can be conducted easily.

Also, preferably, the distance Lc and the distance Ld are the same. With this configuration, the phase difference of ultrasonic waves between two adjacent third ultrasonic elements8cof the third ultrasonic element group3cwhich are electrically connected with each other and the phase difference of ultrasonic waves between two adjacent third ultrasonic elements8dof the third ultrasonic element group3dwhich are electrically connected with each other can be made the same. Therefore, designing can be conducted easily.

Also, preferably, the distance Lb, the distance Lc, and the distance Ld are the same. With this configuration, the phase difference of ultrasonic waves between two adjacent second ultrasonic elements8bof the second ultrasonic element group3bwhich are electrically connected with each other, the phase difference of ultrasonic waves between two adjacent third ultrasonic elements8cof the third ultrasonic element group3cwhich are electrically connected with each other, and the phase difference of ultrasonic waves between two adjacent third ultrasonic elements8dof the third ultrasonic element group3dwhich are electrically connected with each other can be made the same. Therefore, designing can be conducted easily. Here, the above-described expression that “distances are the same” includes a case where the distances are almost the same and a case where the distances are substantially the same as well as a case where the distances are completely the same.

Next, explanations will be made on a usage example of a case where the ultrasonic probe10is applied to the diagnostic device100described below. In this case, the third ultrasonic element group3dis not used. In transmission of ultrasonic waves, any one of the first ultrasonic element group3a, the second ultrasonic element group3b, and the third ultrasonic element group3cis selected and used. In reception of ultrasonic waves, any one of the first ultrasonic element group3a, the second ultrasonic element group3b, and the third ultrasonic element group3cis selected and used. As a display mode, either one of a B (brightness) mode and a harmonic mode is used. Such a case will be explained. However, the third ultrasonic element group3dmay be used instead of the third ultrasonic element group3c. Further, both of the third ultrasonic element group3cand the third ultrasonic element group3dmay be used. The B mode is a display mode which displays an image by changing the intensity of the received ultrasonic waves into brightness (by conducting brightness modulation).

When ultrasonic waves propagate through a living body, the waveform is deformed due to the difference in speed of the ultrasonic waves propagating the living body, which causes high harmonic components with respect to the transmitted ultrasonic waves. The harmonic mode is a display mode which displays an image by receiving the high harmonic components with respect to the transmitted ultrasonic waves. Normally, in the harmonic mode, second harmonic waves, having frequency of twice as much as fundamental waves which are ultrasonic waves to be transmitted or third harmonic waves having frequency of three times, are received. In a case of diagnosing a part of a long distance, the harmonic mode is not used because high harmonic waves are hardly generated. In the harmonic mode, since high harmonic waves are received, the sensitivity can be improved and good ultrasonic images can be obtained.

The resonance frequency of the first ultrasonic element group3ais 1.00 MHz, the resonance frequency of the second ultrasonic element group3bis 1.50 MHz, and the resonance frequencies of the third ultrasonic element groups3cand3dare 3.00 MHz, respectively. Incidentally, 0.5 times-0.9 times of the resonance frequency of the first ultrasonic element group3ais 0.50 MHz-0.90 MHz. 0.5 times-0.9 times of the resonance frequency of the second ultrasonic element group3bis 0.75 MHz-1.35 MHz. 0.5 times-0.9 times of the resonance frequencies of the third ultrasonic element groups3cand3dare 1.5 MHz-2.70 MHz, respectively.

In the following explanations, a long distance refers to a distance that is more than 200 mm and equal to or less than 300 mm. A middle distance refers to a distance that is more than 50 mm and equal to or less than 200 mm. A short distance refers to a distance that is equal to or less than 50 mm. In the ultrasonic probe10, ultrasonic waves can be transmitted and received at various frequencies by changing the combination of the ultrasonic element group that transmits ultrasonic waves and the ultrasonic element group that receives ultrasonic waves, and thus various ultrasonic images can be obtained by using ultrasonic waves of various frequencies. Therefore, the same ultrasonic probe10can be used for diagnosis of parts of a short distance, a middle distance, and a long distance, respectively, without replacing the ultrasonic probe10. Accordingly, a laborious process to an operator can be reduced.

When a part of a short distance is diagnosed, ultrasonic waves are transmitted by the third ultrasonic element group3cthat can generate ultrasonic waves of high frequency, and ultrasonic waves are received by the same third ultrasonic element group3c, for example. Consequently, the resolution can be improved, and a good image of a part of a short distance can be obtained. Further, when a part of a long distance is diagnosed, ultrasonic waves are transmitted by the first ultrasonic element group3aor the second ultrasonic element group3b, and ultrasonic waves are received by the first ultrasonic element group3a, the second ultrasonic element group3b, or the third ultrasonic element group3c, for example. Consequently, a good image of a part of a long distance can be obtained. Further, when the harmonic mode is used, and ultrasonic waves are received by the second ultrasonic element group3bor the third ultrasonic element group3c, for example, a good image of a part of a middle distance or a long distance can be obtained. Next, specific examples will be explained based on Table 1 shown below.

As shown in Table 1, in Configuration 1, the B mode is used, ultrasonic waves are transmitted by the first ultrasonic element group3a, and ultrasonic waves are received by the first ultrasonic element group3a. This configuration is used for diagnosis of a part of a long distance. The frequency of the transmitted ultrasonic waves is 0.60 MHz, for example, and the frequency of the received ultrasonic waves is 0.60 MHz, for example. In Configuration 2, the B mode is used, ultrasonic waves are transmitted by the first ultrasonic element group3a, and ultrasonic waves are received by the first ultrasonic element group3a. This configuration is used for diagnosis of a part of a long distance. The frequency of the transmitted ultrasonic waves is 0.75 MHz, for example, and the frequency of the received ultrasonic waves is 0.75 MHz, for example.

In Configuration 3, the B mode is used, ultrasonic waves are transmitted by the first ultrasonic element group3a, and ultrasonic waves are received by the first ultrasonic element group3a. This configuration is used for diagnosis of a part of a middle distance. The frequency of the transmitted ultrasonic waves is 0.90 MHz, for example, and the frequency of the received ultrasonic waves is 0.90 MHz, for example. In Configuration 4, the harmonic mode is used, ultrasonic waves are transmitted by the first ultrasonic element group3a, and ultrasonic waves are received by the second ultrasonic element group3b. This configuration is used for diagnosis of a part of a long distance. The frequency of the transmitted ultrasonic waves is 0.60 MHz, for example, and the frequency of the received ultrasonic waves is 1.20 MHz, for example.

In Configuration 5, the harmonic mode is used, ultrasonic waves are transmitted by the first ultrasonic element group3a, and ultrasonic waves are received by the second ultrasonic element group3b. This configuration is used for diagnosis of a part of a middle distance. The frequency of the transmitted ultrasonic waves is 0.75 MHz, for example, and the frequency of the received ultrasonic waves is 1.50 MHz, for example. In Configuration 6, the harmonic mode is used, ultrasonic waves are transmitted by the first ultrasonic element group3a, and ultrasonic waves are received by the third ultrasonic element group3c. This configuration is used for diagnosis of a part of a long distance. The frequency of the transmitted ultrasonic waves is 0.60 MHz, for example, and the frequency of the received ultrasonic waves is 1.80 MHz, for example.

In Configuration 7, the B mode is used, ultrasonic waves are transmitted by the second ultrasonic element group3b, and ultrasonic waves are received by the second ultrasonic element group3b. This configuration is used for diagnosis of a part of a middle distance. The frequency of the transmitted ultrasonic waves is 0.90 MHz, for example, and the frequency of the received ultrasonic waves is 0.90 MHz, for example. In Configuration 8, the B mode is used, ultrasonic waves are transmitted by the second ultrasonic element group3b, and ultrasonic waves are received by the first ultrasonic element group3a. This configuration is used for diagnosis of a part of a middle distance. The frequency of the transmitted ultrasonic waves is 0.90 MHz, for example, and the frequency of the received ultrasonic waves is 0.90 MHz, for example.

In Configuration 9, the B mode is used, ultrasonic waves are transmitted by the second ultrasonic element group3b, and ultrasonic waves are received by the second ultrasonic element group3b. This configuration is used for diagnosis of a part of a middle distance. The frequency of the transmitted ultrasonic waves is 1.20 MHz, for example, and the frequency of the received ultrasonic waves is 1.20 MHz, for example. In Configuration 10, the B mode is used, ultrasonic waves are transmitted by the second ultrasonic element group3b, and ultrasonic waves are received by the second ultrasonic element group3b. This configuration is used for diagnosis of a part of a middle distance. The frequency of the transmitted ultrasonic waves is 1.35 MHz, for example, and the frequency of the received ultrasonic waves is 1.35 MHz, for example.

In Configuration 11, the harmonic mode is used, ultrasonic waves are transmitted by the second ultrasonic element group3b, and ultrasonic waves are received by the third ultrasonic element group3c. This configuration is used for diagnosis of a part of a long distance. The frequency of the transmitted ultrasonic waves is 1.20 MHz, for example, and the frequency of the received ultrasonic waves is 2.40 MHz, for example. In Configuration 12, the harmonic mode is used, ultrasonic waves are transmitted by the second ultrasonic element group3b, and ultrasonic waves are received by the third ultrasonic element group3c. This configuration is used for diagnosis of a part of a long distance. The frequency of the transmitted ultrasonic waves is 1.35 MHz, for example, and the frequency of the received ultrasonic waves is 2.70 MHz, for example.

In Configuration 13, the harmonic mode is used, ultrasonic waves are transmitted by the second ultrasonic element group3b, and ultrasonic waves are received by the third ultrasonic element group3c. This configuration is used for diagnosis of a part of a long distance. The frequency of the transmitted ultrasonic waves is 1.00 MHz, for example, and the frequency of the received ultrasonic waves is 3.00 MHz, for example. In Configuration 14, the B mode is used, ultrasonic waves are transmitted by the third ultrasonic element group3c, and ultrasonic waves are received by the third ultrasonic element group3c. This configuration is used for diagnosis of a part of a short distance. The frequency of the transmitted ultrasonic waves is 1.80 MHz, for example, and the frequency of the received ultrasonic waves is 1.80 MHz, for example.

In Configuration 15, the B mode is used, ultrasonic waves are transmitted by the third ultrasonic element group3c, and ultrasonic waves are received by the third ultrasonic element group3c. This configuration is used for diagnosis of a part of a short distance. The frequency of the transmitted ultrasonic waves is 2.40 MHz, for example, and the frequency of the received ultrasonic waves is 2.40 MHz, for example. In Configuration 16, the B mode is used, ultrasonic waves are transmitted by the third ultrasonic element group3c, and ultrasonic waves are received by the third ultrasonic element group3c. This configuration is used for diagnosis of a part of a short distance. The frequency of the transmitted ultrasonic waves is 2.70 MHz, for example, and the frequency of the received ultrasonic waves is 2.70 MHz, for example.

In the above examples, any one of the first ultrasonic element group3a, the second ultrasonic element group3b, and the third ultrasonic element group3cis selected and used for transmission of ultrasonic waves, and any one of the first ultrasonic element group3a, the second ultrasonic element group3b, and the third ultrasonic element group3cis selected and used for reception of ultrasonic waves. However, the invention is not limited to these examples. Any two of the first ultrasonic element group3a, the second ultrasonic element group3b, and the third, ultrasonic element group3cmay be selected and used, or all of them may be used, for transmission of ultrasonic waves. Also, any two of the first ultrasonic element group3a, the second ultrasonic element group3b, and the third ultrasonic element group3cmay be selected and used, or all of them may be used, for reception of ultrasonic waves.

Modification Example of Ultrasonic Transducer

In the ultrasonic transducer1according to the above-described embodiment, the number of the first ultrasonic element8aof the first ultrasonic element group3ais one. However, the number may be two, or may be three or more. Here, explanations will be made on a case where the number of the first ultrasonic element8aof the first ultrasonic element group3ais three or more in the ultrasonic transducer1.

Preferably, the conducting wire for a lower electrode711athat is a wiring for electrically connecting each first ultrasonic element8aof the first ultrasonic element group3ain series is provided such that the total sum of distances of the conducting wires for a lower electrode711abetween two adjacent first ultrasonic elements8awhich are electrically connected with each other becomes shortest. With this configuration, the voltage drop in the conducting wire for a lower electrode711acan be reduced.

Preferably, in the conducting wire for a lower electrode711athat is a wiring for electrically connecting each first ultrasonic element8aof the first ultrasonic element group3ain series, all of the distances of the conducting wires for a lower electrode711abetween two adjacent first ultrasonic elements8aof the first ultrasonic element group3awhich are electrically connected with each other are the same. With this configuration, the phase difference of ultrasonic waves between two adjacent first ultrasonic elements8awhich are electrically connected with each other can be made the same in the first ultrasonic element group3a, and thus designing can be conducted easily.

Also, preferably, the distance of the conducting wire for a lower electrode711abetween two adjacent first ultrasonic elements8aof the first ultrasonic element group3awhich are electrically connected with each other, the distance Lb, the distance Lc, and the distance Ld are the same. With this configuration, the phase difference of ultrasonic waves between two adjacent first ultrasonic elements8aof the first ultrasonic element group3awhich are electrically connected with each other, the phase difference of ultrasonic waves between two adjacent second ultrasonic elements8bof the second ultrasonic element group3bwhich are electrically connected with each other, the phase difference of ultrasonic waves between two adjacent third ultrasonic elements8cof the third ultrasonic element group3cwhich are electrically connected with each other, and the phase difference of ultrasonic waves between two adjacent third ultrasonic elements8dof the third ultrasonic element group3dwhich are electrically connected with each other can be made the same. Therefore, designing can be conducted easily. The ultrasonic probe10and the ultrasonic transducer1described above can be applied to various kinds of electronic instruments such as diagnostic devices in a preferred manner. Hereinafter, an embodiment of a diagnostic device will be explained as a representative of an embodiment of an electronic instrument.

Embodiment of Diagnostic Device (Electronic Instrument)

FIG. 6is a perspective view showing an embodiment of the diagnostic device according to the invention.FIG. 7is a block diagram showing the embodiment of the diagnostic device according to the invention. As shown inFIG. 6andFIG. 7, the diagnostic device100has the above-described ultrasonic probe10, and the device main body300which is electrically connected with the ultrasonic probe10through the cable210.

The device main body300has a control section (control means)310, a drive signal generating section320, a detection signal processing section330, an image signal processing section340, and an image display section (display means)350. The signal processing section is constructed of the detection signal processing section330and the image signal processing section340. The control section310is constructed of a microcomputer and the like, for example, and controls the entire device main body300such as the drive signal generating section320and the image signal processing section340. The image display section350is constructed of a display device such as a CRT or an LCD, for example.

Next, the operation of the diagnostic device100will be explained. In conducting a test, the surface of the acoustic matching section6of the ultrasonic probe10is applied to a living body as a test target, and the diagnostic device100is activated. First, the control section310outputs a transmission order to the drive signal generating section320, the drive signal generating section320transmits a drive signal for driving each ultrasonic element8to the ultrasonic element8at a predetermined timing. In this manner, each of the ultrasonic elements8is driven at a predetermined timing. Then, ultrasonic waves are transmitted from the ultrasonic transducer1of the ultrasonic probe10.

The transmitted ultrasonic waves propagate through a living body, and the ultrasonic waves reflected on a predetermined part of the living body are input to the ultrasonic transducer1of the ultrasonic probe10. Then, a detection signal corresponding to the input ultrasonic waves are output from the ultrasonic transducer1. The detection signal is transmitted to the detection signal processing section330of the device main body300through the cable210. The detection signal undergoes predetermined signal processing in the detection signal processing section330, and is converted into a digital signal by an A/D converter included in the detection signal processing section330. The A/D converter is not shown in the drawing.

The digital signal output from the detection signal processing section330is input to the image signal processing section340, and is sequentially stored in a primary storing section included in the image signal processing section340as areal data in synchronization with a frame timing signal. The primary storing section is not shown in the drawing. The image signal processing section340reconstructs two-dimensional or three-dimensional image data based on each areal data, and also conducts image processing such as interpolation, response emphasis processing, or tone processing to the image data. The image data, to which image processing has been conducted, is stored in a secondary storing section included in the image signal processing section340. The secondary storing section is not shown in the drawing.

The image data, to which image processing has been conducted, is then read out from the secondary storing section of the image signal processing section340and is input to the image display section350. The image display section350displays an image based on the image data. A medical service worker such as a doctor conducts diagnosis or the like by observing an image displayed on the image display section350. The invention is not limited to the ultrasonic transducer, the ultrasonic probe, the diagnostic device, and the electronic instrument of the invention explained in the above based on the embodiment shown in the drawing. The configuration of each section can be replaced with any configuration that has a similar function. Also, another optional element may be added to the invention.

In the above-described embodiment, the cell unit is arranged two-dimensionally. However, the invention is not limited to this, and the cell unit can be arranged one-dimensionally, for example. Further, in the above-described embodiment, the cell units are plural. However, the invention is not limited to this, and the cell unit may be single. Further, in the above-described embodiment, the cell unit has three kinds (three sizes) of ultrasonic element groups in which the areas of the diaphragms are different. However, the invention is not limited to this, and the cell unit may have two kinds (two sizes) of ultrasonic element groups in which the areas of the diaphragms are different, or may have four or more kinds (four or more sizes) of ultrasonic element groups in which the areas of the diaphragms are different.

In the above-described embodiment, the ultrasonic element of the first ultrasonic element group is single. However, the invention is not limited to this, and a plurality of ultrasonic elements may be provided in the first ultrasonic element group. In such a case, the first ultrasonic elements of the first ultrasonic element group are electrically connected in series. Further, according to the invention, the ultrasonic transducer (the ultrasonic probe) is not limited to a contact type sensor that is used by being brought into contact with a test target, and can be applied to a non-contact type sensor such as a proximity sensor that is used without being brought into contact with a test target.

GENERAL INTERPRETATION OF TERMS