JP5310119B2 - Ultrasonic sensor unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic sensor unit capable of showing the maximum performance in both cases at a transmission time and a reception time of an ultrasonic wave. <P>SOLUTION: This sensor unit includes an ultrasonic transmitting sensor array having a plurality of ultrasonic transmitting sensors 52 respectively formed of a piezoelectric body 3 on the transmission side surface, and an ultrasonic receiving sensor array having a plurality of ultrasonic receiving sensors 53 respectively formed of a piezoelectric body 3 on the reception side surface. Each sensor array is described as follows: each ultrasonic transmitting sensor 52 and each ultrasonic receiving sensor 53 are not overlapped in a plan view; either of the transmission side surface and the reception side surface is faced to a direction reverse to an ultrasonic transmission direction of the ultrasonic transmitting sensor 52; the transmission side surface and the reception side surface are laminated together; and, in one sensor array, a through hole 11b for exposing the ultrasonic receiving sensor 53 of the other sensor array is formed. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an ultrasonic sensor unit.

  Ultrasonic sensors are used in many measurements and detections, such as measuring the distance to a target object, measuring flow velocity, and nondestructive inspection of piping. As such an ultrasonic sensor, a diaphragm type sensor is conventionally known. In this ultrasonic sensor, a thin film layer of PZT ceramics sandwiched between two electrodes is formed on one surface side of a diaphragm, and ultrasonic waves are detected using electrical signals output from these electrodes (for example, , See Patent Document 1).

  In recent years, an ultrasonic sensor array in which a large number of ultrasonic sensors are arranged in an array using MEMS (Micro Electro Mechanical Systems) technology can generate ultrasonic waves having sharp directivity in a desired direction. Research and development are being carried out to realize three-dimensional scanning using arrays.

JP 2005-49301 A

By the way, in the ultrasonic sensor array manufactured by the MEMS technology, the diaphragm structure constituting the ultrasonic sensor is basically the same among all the sensors. In order to reduce the size of the ultrasonic sensor array, it is effective to form an array by forming a transmission ultrasonic sensor and an ultrasonic reception sensor on the same substrate.
However, when the MEMS technology is used, the transmitting element and the receiving element formed on the same substrate have the same diaphragm structure. The transmission ultrasonic sensor and the ultrasonic reception sensor have different optimum diaphragm structures. For this reason, the ultrasonic sensor for transmission and the ultrasonic sensor for receiving ultrasonic waves cannot maximize the performance of each, and a new technology has been desired to be provided.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an ultrasonic sensor unit capable of maximizing performance both when transmitting and receiving ultrasonic waves.

  In order to solve the above-described problems, an ultrasonic sensor unit according to the present invention includes an ultrasonic transmission sensor array having a plurality of ultrasonic transmission sensors each including a piezoelectric body that transmits ultrasonic waves, and the ultrasonic wave. An ultrasonic wave reception sensor array having a plurality of ultrasonic wave reception sensors made of a piezoelectric body for receiving the ultrasonic wave, the ultrasonic wave transmission sensor array and the ultrasonic wave reception sensor array, The ultrasonic wave transmission sensor and the ultrasonic wave reception sensor do not overlap in a plan view, and the ultrasonic wave transmission sensor array of the ultrasonic wave transmission sensor array includes the ultrasonic wave transmission sensor, and the ultrasonic wave reception The ultrasonic sensor is attached to the receiving side surface of the sensor array on which the ultrasonic receiving sensor is provided so as to face in the same direction. While the of Saarei and the ultrasonic reception sensor array, wherein the through-holes for exposing the ultrasonic sensor is formed in the other array.

  According to the ultrasonic sensor unit of the present invention, since the ultrasonic transmission sensor array and the ultrasonic reception sensor are independently provided, for example, the ultrasonic transmission sensor array and the ultrasonic reception sensor are optimally suited to each. By configuring under conditions, it is possible to realize a configuration including an ultrasonic transmission sensor that emits strong sound pressure and an ultrasonic reception sensor that has excellent reception sensitivity. Therefore, it is possible to provide a highly reliable product that can exhibit the maximum performance both when transmitting and receiving ultrasonic waves. Further, since the ultrasonic reception sensor array and the transmission ultrasonic sensor array are bonded together, the rigidity of the sensor unit itself is increased, and the reliability at the time of transmission and reception of ultrasonic waves can be improved.

  In order to solve the above-described problem, an ultrasonic sensor unit of the present invention includes an ultrasonic transmission sensor array having a plurality of ultrasonic transmission sensors made of a piezoelectric body that transmits ultrasonic waves on one surface thereof, An ultrasonic reception sensor array having a plurality of ultrasonic reception sensors made of a piezoelectric body for receiving ultrasonic waves on one side surface thereof, the ultrasonic transmission sensor array and the ultrasonic reception sensor array, The ultrasonic transmitting sensor and the ultrasonic receiving sensor do not overlap in a plan view, and the ultrasonic transmitting sensor array includes the transmitting side surface provided with the ultrasonic transmitting sensor; Either one of the reception-side surfaces of the ultrasonic wave reception sensor array provided with the ultrasonic wave reception sensor is configured to transmit the ultrasonic wave of the ultrasonic wave transmission sensor. An ultrasonic sensor in the other array is disposed in one of the ultrasonic transmission sensor array and the ultrasonic reception sensor array. A through-hole exposing the surface is formed.

According to the ultrasonic sensor unit of the present invention, the ultrasonic transmission sensor array and the ultrasonic reception sensor array include an ultrasonic transmission sensor and an ultrasonic reception sensor. Are attached in a state of facing each other, so that each wiring formed on each surface can be easily connected and shared.
In particular, the ground wiring that holds a constant voltage is shared between the electrode pair that applies a voltage to the piezoelectric body of the ultrasonic transmission sensor and the electrode pair that extracts the voltage generated from the piezoelectric body of the ultrasonic reception sensor. Can do. If the ground wiring is formed on either the transmission-side surface or the reception-side surface, it is only necessary to form a lead-out wiring that serves as a connection terminal for the ground wiring on the other surface, thus reducing manufacturing costs. Can be planned.

  Furthermore, in order to solve the above-described problem, an ultrasonic sensor unit of the present invention includes an ultrasonic transmission sensor array having a plurality of ultrasonic transmission sensors made of a piezoelectric body that transmits ultrasonic waves on one side surface thereof, An ultrasonic reception sensor array having a plurality of ultrasonic reception sensors made of a piezoelectric body for receiving ultrasonic waves on one side surface thereof, the ultrasonic transmission sensor array and the ultrasonic reception sensor array, The ultrasonic transmitting sensor and the ultrasonic receiving sensor do not overlap in a plan view, and the ultrasonic transmitting sensor array includes the transmitting side surface provided with the ultrasonic transmitting sensor; Either one of the reception-side surfaces provided with the ultrasonic reception sensor of the ultrasonic wave reception sensor array is the ultrasonic wave of the ultrasonic transmission sensor. The transmission side rear surface that is opposite to the transmission direction and is not equipped with the ultrasonic transmission sensor of the ultrasonic transmission sensor array, and the reception side rear surface that is not equipped with the ultrasonic reception sensor of the ultrasonic reception sensor array And a through hole for exposing the ultrasonic sensor in the other array is formed in one of the ultrasonic transmission sensor array and the ultrasonic reception sensor array.

  According to the ultrasonic sensor unit of the present invention, the ultrasonic transmission sensor array and the ultrasonic reception sensor array are bonded to each other on the transmission-side back surface and the reception-side back surface. The base of each sensor array is interposed between the sensors for use. Therefore, the vibration when the ultrasonic wave is generated by the ultrasonic transmission sensor is difficult to propagate to the ultrasonic reception sensor, so that the ultrasonic reception sensor can be made more sensitive. In addition, on the contrary, the influence on the ultrasonic wave reception sensor is reduced, so that the sound pressure at the time of transmission of the ultrasonic wave transmission sensor can be increased. Therefore, it is possible to provide a highly reliable ultrasonic sensor unit that can exhibit better performance and has less crosstalk.

  In the ultrasonic sensor unit, the ultrasonic transmission sensor is regularly arranged in the ultrasonic transmission sensor array, and the ultrasonic reception sensor is regularly arranged in the ultrasonic reception sensor array. Is preferably arranged.

  According to this configuration, since the ultrasonic transmission sensors are regularly arranged, the ultrasonic transmission sensor array can transmit ultrasonic waves with a strong sound pressure. In addition, since the ultrasonic receiving sensors are regularly arranged, the ultrasonic receiving sensor array can receive the ultrasonic waves transmitted from the ultrasonic transmitting sensor array with excellent sensitivity.

In the ultrasonic sensor unit, an arrangement pattern of the ultrasonic transmission sensor in the ultrasonic transmission sensor array is different from an arrangement pattern of the ultrasonic reception sensor in the ultrasonic reception sensor array. It is preferable. Furthermore, the ultrasonic transmission sensor and the ultrasonic reception sensor are more preferably either a piezoelectric sensor or a capacitive sensor.
In this way, since a piezoelectric or capacitive sensor is used, the degree of freedom in designing the ultrasonic transmission sensor array and the ultrasonic reception sensor array can be improved. Therefore, it is possible to provide an ultrasonic sensor unit that can exhibit the maximum performance under desired conditions.

In the ultrasonic sensor unit, it is preferable that the number of the ultrasonic transmission sensors in the ultrasonic transmission sensor array is different from the number of the ultrasonic reception sensors in the ultrasonic reception sensor array.
In this way, by changing the number of ultrasonic sensors between the two sensor arrays, the ultrasonic transmission sensor array and the ultrasonic reception sensor array can be designed under optimum conditions.

It is a perspective view of PDA. 1 is a perspective view of an ultrasonic sensor array according to a first embodiment. It is a figure which shows the component of an ultrasonic sensor unit. It is a figure which shows the plane structure of an ultrasonic sensor unit. It is a system block diagram of the control part of an ultrasonic sensor unit. It is a figure which expands the principal part of an ultrasonic sensor unit. It is a top view of the lower electrode in the sensor for ultrasonic transmission. It is sectional drawing which shows the state which the diaphragm of the ultrasonic sensor bent. It is a figure which shows the component of the ultrasonic sensor unit which concerns on 2nd embodiment. It is a figure which shows the plane structure of the ultrasonic sensor unit which concerns on 2nd embodiment. It is a schematic diagram which shows the principal part of each ultrasonic sensor unit which concerns on 1st embodiment, 3rd embodiment, and 4th embodiment. It is a figure which expands the principal part of the ultrasonic sensor unit concerning a third embodiment.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In each of the following drawings, the scale is appropriately changed for each layer or member so that each layer or member can be recognized in the drawing. In the following description, a PDA (Personal Data Assistance) including the ultrasonic sensor unit of the present invention will be described as an example.

(First embodiment)
FIG. 1 is a perspective view schematically showing the configuration of the PDA of this embodiment. FIG. 2 is a perspective view schematically showing the configuration of the ultrasonic sensor unit provided in the PDA of this embodiment. FIG. 3A is a diagram showing a planar configuration of an ultrasonic transmission sensor unit as a component of the ultrasonic sensor unit, and FIG. 3B is an ultrasonic reception sensor as a component of the ultrasonic sensor unit. It is a figure which shows the planar structure of a unit. FIG. 4 is a diagram illustrating a planar configuration of the ultrasonic sensor unit. FIG. 5 is a system configuration diagram schematically showing the configuration of the control unit of the ultrasonic sensor unit of the present embodiment. In FIG. 5, the configuration for applying a constant voltage to the second lower electrode, which will be described later, is omitted.

  As shown in FIG. 1, the PDA 100 of this embodiment includes a display unit 20 in a main body 30. The display unit 20 includes, for example, a liquid crystal panel, an organic EL panel, and the like, and is connected to a calculation / control unit housed in the main body 30 and configured to display various operation images and other information. An ultrasonic sensor unit 10 is installed on the outer periphery of the main body 30. The ultrasonic sensor unit 10 functions as an input device that detects the shape and operation of a human hand, finger, or input pen and inputs it to the PDA 100, for example.

  As shown in FIG. 2, the ultrasonic sensor unit 10 includes an ultrasonic transmission sensor array 50 and an ultrasonic reception sensor array 51. The ultrasonic transmission sensor array 50 includes a plurality of ultrasonic transmission sensors 52 that transmit ultrasonic waves. The ultrasonic reception sensor array 51 includes a plurality of ultrasonic reception sensors 53 that receive ultrasonic waves. Although details will be described later, each of the ultrasonic transmission sensor 52 and the ultrasonic reception sensor 53 according to the present embodiment is composed of a piezoelectric ultrasonic sensor.

  As shown in FIG. 3A, the ultrasonic transmission sensor array 50 includes a base 11 made of, for example, a single crystal silicon substrate. A plurality of openings 11a having a substantially circular shape in plan view are formed in the base 11 in an array. Each of the openings 11a is provided with an ultrasonic transmission sensor 52 that transmits ultrasonic waves. That is, the ultrasonic transmission sensor array 50 has a configuration in which a plurality of ultrasonic transmission sensors 52 are regularly arranged in an array on one surface of the base 11. Specifically, in the present embodiment, a plurality of ultrasonic transmission sensors 52 are arranged in a matrix.

  Further, the base portion 11 is regularly formed with a plurality of through holes 11b having a substantially square shape in plan view in a matrix shape. Specifically, the through holes 11b are formed in the base 11 so as to be staggered with respect to the openings 11a.

  As shown in FIG. 3B, the ultrasonic wave receiving sensor array 51 includes a base 61 made of, for example, a single crystal silicon substrate. A plurality of openings 61a having a substantially circular shape in plan view are formed in the base 61 in an array. The ultrasonic reception sensor 53 is provided in each of the openings 61a. That is, the ultrasonic receiving sensor array 51 has a configuration in which a plurality of ultrasonic receiving sensors 53 are regularly arranged in an array on one surface of the base 61.

  In the present embodiment, the number of ultrasonic transmission sensors 52 in the ultrasonic transmission sensor array 50 is different from the number of ultrasonic reception sensors 53 in the ultrasonic reception sensor array 51. Specifically, the ultrasonic sensor unit 10 includes more ultrasonic transmission sensors 52 than the ultrasonic reception sensors 53. Thus, by making the number of ultrasonic sensors different between the two sensor arrays 50 and 51, the ultrasonic transmission sensor array 50 and the ultrasonic reception sensor array 51 are respectively designed under optimum conditions. Yes.

  As shown in FIG. 2, the ultrasonic sensor unit 10 is configured by bonding an ultrasonic transmission sensor array 50 and an ultrasonic reception sensor array 51 together. That is, the ultrasonic transmission sensor array 50 and the ultrasonic reception sensor array 51 are independently formed.

  As shown in FIG. 4, the ultrasonic transmission sensor array 50 and the ultrasonic reception sensor array 51 are bonded so that the ultrasonic transmission sensor 52 and the ultrasonic reception sensor 53 do not overlap in a plan view. It has become.

Specifically, the ultrasonic reception sensor 53 is exposed in the through hole 11 b formed in the base 11 of the ultrasonic transmission sensor unit 50. Thereby, the ultrasonic reception sensor array 51 can receive predetermined ultrasonic waves by the ultrasonic reception sensor array 51 exposed in the through hole 11b.
The ultrasonic receiving sensor array 51 and the ultrasonic transmitting sensor array 50 have the same outer shape, and the ultrasonic sensor unit 10 has a substantially rectangular shape in plan view.

  Each of the ultrasonic transmission sensor 52 and the ultrasonic reception sensor 53 is connected to a wiring (not shown), and each wiring is connected to the terminal portion 13 a of the control board 13 through the flexible printed board 12. The control board 13 is provided with a control unit 40 including a calculation unit, a storage unit, and the like. The control unit 40 is configured to control an input signal input to the ultrasonic transmission sensor 52 and process an output signal output from the ultrasonic reception sensor 53.

  As shown in FIG. 5, the control unit 40 is connected to the ultrasonic sensor unit 10, and mainly transmits / receives the control / calculation unit 41, the storage unit 42, the ultrasonic wave generation unit 43, and the ultrasonic wave detection unit 44. And a T / R switch 45 for switching. The ultrasonic wave generator 43 includes a sine wave generator 43a that generates a sine wave, a phase shifter 43b that is provided in each ultrasonic sensor 1 and changes the phase of the sine wave, and a driver 43c. The ultrasonic detection unit 44 mainly includes an amplification unit 44a and an A / D conversion unit 44b.

  When the ultrasonic sensor unit 10 transmits ultrasonic waves, the control / calculation unit 41 generates a sine wave by the sine wave generation unit 43a, and the sine wave corresponds to each ultrasonic transmission sensor 52 by the phase shift unit 43b. Change to phase. Further, when the ultrasonic sensor unit 10 receives ultrasonic waves, the control / calculation unit 41 switches the T / R switch 45 to transmit the output signal output from the ultrasonic reception sensor 53 to the amplification unit 44a. The control / calculation unit 41 is configured to be able to output information stored in the storage unit 42 to a control / calculation unit (not shown) of the PDA 100.

  FIG. 6 is an enlarged cross-sectional view in which the ultrasonic sensor unit 10 shown in FIG. 2 is cut along line A-A ′ and one of the ultrasonic transmission sensor 52 and the ultrasonic reception sensor 53 is enlarged. FIG. 7 is a plan view of the lower electrode in the ultrasonic transmission sensor 52. Note that the cross-sectional view of FIG. 6 corresponds to a cross section taken along line B-B ′ of FIG. 7.

  As shown in FIG. 6, the ultrasonic transmission sensor 52 includes a diaphragm 2 provided so as to close the opening 11 a of the base 11, and a piezoelectric body 3 provided on the opposite side of the base 11 of the diaphragm 2. And a lower electrode 4 and an upper electrode 5 connected to the piezoelectric body 3. The depth d of the opening 11a formed in the base 11 is, for example, about 180 μm to 200 μm.

  The ultrasonic reception sensor 53 includes a diaphragm 2 provided so as to close the opening 61 a of the base 61, a piezoelectric body 3 provided on the side opposite to the base 11 of the diaphragm 2, and the piezoelectric body 3. A lower electrode 4 and an upper electrode 5 connected to each other. The ultrasonic reception sensor 53 is exposed in the through hole 11 b formed in the base 11 of the ultrasonic transmission sensor 52.

  By the way, since the ultrasonic transmission sensor array 50 is configured by regularly arranging the ultrasonic transmission sensors 52, the ultrasonic waves can be transmitted with a strong sound pressure. Further, since the ultrasonic reception sensor array 51 is configured by regularly arranging the ultrasonic reception sensors 53, the ultrasonic reception sensor array 51 is transmitted from the ultrasonic transmission sensor array 50. Ultrasonic waves can be received with excellent sensitivity.

  Further, in the present embodiment, the ultrasonic transmission sensor 52 and the ultrasonic reception sensor 53 are independently formed by the MEMS technology. Therefore, since the ultrasonic transmission sensor 52 in the ultrasonic transmission sensor array 50 is formed so as to satisfy the optimum conditions for ultrasonic transmission, it is possible to transmit ultrasonic waves with higher sound pressure. . In addition, since the ultrasonic reception sensor 53 in the ultrasonic reception sensor array 51 is formed so as to satisfy the optimum conditions for ultrasonic reception, the diaphragm can be received even when weak ultrasonic waves attenuated by bounced off the object are received. Thus, a greater output sensitivity can be obtained.

  Here, the configuration of the ultrasonic transmission sensor 52 will be described in detail. The configuration of the ultrasonic wave reception sensor 53 is the same as the configuration of the diaphragm 2 and the piezoelectric body 3 although the thicknesses thereof are different.

Diaphragm 2, a first oxide film 2a formed by being for example SiO ₂ is provided on the base 11 side, a second oxide formed by being laminated on the opposite side e.g. ZrO ₂ is the base 11 of the first oxide film 2a It has a two-layer structure with the film 2b. The first oxide film 2a is formed to a thickness of about 3 μm, for example, by thermally oxidizing the surface of a single crystal silicon substrate. The second oxide film is formed to a thickness of, for example, about 400 nm by, for example, a CVD (chemical vapor deposition) method.

A region where the diaphragm 2 is planarly overlapped with the opening 11 a and exposed to the opening 11 a is a vibration region V of the diaphragm 2. The diameter D of the opening 11a is appropriately set in a range of about 100 μm to several hundred μm, for example, according to the natural frequency of the diaphragm 2 in the vibration region V.
A lower electrode 4 is provided on the surface opposite to the base 11 in the vibration region V of the diaphragm 2.

  As shown in FIGS. 6 and 7, the lower electrode 4 is separated into a first lower electrode 4 a provided in the center of the vibration region V and a second lower electrode 4 b provided in the periphery thereof. The first lower electrode 4a and the second lower electrode 4b are connected to wirings 6a and 6b connected to the control unit 40 of the ultrasonic sensor unit 10, respectively. The lower electrode 4 is formed to a thickness of about 200 nm from a conductive metal material such as Ir. On the lower electrode 4, the piezoelectric body 3 is provided outside the vibration region V and its boundary so as to cover the lower electrode 4.

The piezoelectric body 3 is made of, for example, PZT (lead zirconate titanate), BaTiO ₃ (barium titanate) or the like, and includes a first piezoelectric portion 3a at the center and a second piezoelectric portion 3b at the periphery. In other words, the piezoelectric body 3 is integrally formed, and the first lower electrode 4a and the second lower electrode 4b are separated, so that the portion corresponding to the first lower electrode 4a of the piezoelectric body 3 is the first piezoelectric portion. The portion corresponding to the second lower electrode 4b of the piezoelectric body 3 is the second piezoelectric portion 3b.

The first piezoelectric portion 3a is a central portion of the piezoelectric body 3 connected to the first lower electrode 4a. The first piezoelectric portion 3a is for deforming by the applied voltage to vibrate the diaphragm 2, or to deform by the vibration of the diaphragm 2 to generate a potential difference.
The second piezoelectric portion 3b is a peripheral portion of the piezoelectric body 3 connected to the second lower electrode 4b. The second piezoelectric portion 3b is for deforming by the applied voltage to bend the diaphragm 2 statically. The second piezoelectric portion 3b is provided in the vicinity of the boundary of the vibration region V so as to straddle the boundary of the vibration region V.

  An upper electrode 5 is formed on the piezoelectric body 3. The upper electrode 5 is formed of a conductive metal material such as Ir, and is connected to the first piezoelectric portion 3a and the second piezoelectric portion 3b. The thickness of the upper electrode 5 is about 50 nm, for example. The upper electrode 5 is connected to the control unit 40 of the ultrasonic sensor unit 10 via the wiring 7. Based on such a configuration, the ultrasonic transmission sensor array 50 can transmit ultrasonic waves having higher sound pressure.

Next, the operation of the PDA 100 according to this embodiment will be described.
As shown in FIG. 1, when the PDA 100 detects the shape or movement of a human hand or finger, the ultrasonic sensor unit 10 transmits ultrasonic waves to the detection area.

  Specifically, first, a constant voltage is applied between the upper electrode 5 and the second lower electrode 4b of the ultrasonic transmission sensor 52 by the control unit 40 of the ultrasonic sensor unit 10. As shown in FIG. 6, when the voltage is applied between the upper electrode 5 and the second lower electrode 4b, the second piezoelectric portion 3b formed so as to straddle the boundary of the vibration region V of the diaphragm 2 is applied. It is expanded or compressed in the surface direction of the diaphragm 2 according to the voltage.

  When the second piezoelectric portion 3b is extended in the plane direction of the diaphragm 2, the piezoelectric body 3 side of the diaphragm 2 is extended in the plane direction in the vicinity of the boundary of the vibration region V of the diaphragm 2, as shown in FIG. As shown, the vibration region V of the diaphragm 2 is bent so as to be convex toward the base 11 side (convex downward in the figure). Further, when the second piezoelectric portion 3b is compressed in the plane direction of the diaphragm 2, the piezoelectric body 3 side of the diaphragm 2 is compressed in the plane direction in the vicinity of the boundary of the vibration region V of the diaphragm 2, and FIG. ), The vibration region V of the diaphragm 2 is bent so as to be concave (convex upward in the figure) toward the base 11 side.

  In this way, by controlling the applied voltage applied to the second piezoelectric portion 3b of each ultrasonic transmission sensor 52, the amount of static deflection and the direction of deflection of the diaphragm 2 of the ultrasonic transmission sensor 52 are desired. Control to the state. Further, by maintaining the applied voltage to the second piezoelectric portion 3b of each ultrasonic transmission sensor 52 at a constant voltage, the vibration region V of the diaphragm 2 is statically bent into a desired shape. Keep it.

  Next, in a state where the vibration region V of the diaphragm 2 is statically bent, a sine wave is generated by the sine wave generation unit 43a of the control unit 40 as shown in FIG. 3, and the phase shift unit 43b, the driver 43c, Through the T / R switch 45, a sine wave voltage whose phase is slightly shifted is applied to the first lower electrode 14a of each ultrasonic transmission sensor 52 of the ultrasonic sensor unit 10. Accordingly, the first piezoelectric portion 3 a of each ultrasonic transmission sensor 52 expands and contracts in the surface direction of the diaphragm 2, and the vibration region V of the diaphragm 2 vibrates in the normal direction of the diaphragm 2.

Here, a sine wave voltage whose phase is slightly shifted is applied to the first lower electrode 4 a of each ultrasonic transmission sensor 52. As a result, the diaphragm 2 in the vibration region V of each ultrasonic transmission sensor 52 vibrates in a state where the phase is slightly shifted.
When the diaphragm 2 in the vibration region V of each ultrasonic transmission sensor 52 vibrates in a state of being slightly shifted in phase, ultrasonic waves emitted from the respective ultrasonic transmission sensors 52 interfere with each other. Due to the interference of the ultrasonic waves emitted from each of the ultrasonic transmission sensors 52, the ultrasonic traveling direction is inclined with respect to the normal direction of the diaphragm 2, and directivity is imparted to the ultrasonic waves.

  The ultrasonic sensor unit shown in FIG. 1 is changed by changing the phase shift of the sine wave voltage applied to the first piezoelectric portion 3a of each ultrasonic transmission sensor 52 using the change in directivity of the ultrasonic waves. 10 (the ultrasonic transmission sensor array 50) changes the direction of ultrasonic waves transmitted, and scans the detection area of the PDA 100.

  At this time, for example, if a human hand or finger is present in the detection region as shown in FIG. 1, the ultrasonic wave transmitted from the ultrasonic sensor unit 10 is reflected by the human hand or finger. When the ultrasonic wave reflected by a human hand or finger reaches the ultrasonic wave reception sensor 53 through the through holes 11 b provided in the ultrasonic wave transmission sensor array 50, the ultrasonic wave of the diaphragm 2 of the ultrasonic wave reception sensor 53 is detected. The vibration region V vibrates. When the vibration region V of the diaphragm 2 vibrates, the first piezoelectric portion 3a expands and contracts along with the expansion and contraction in the surface direction of the diaphragm 2, and a potential difference is generated in the first piezoelectric portion 3a.

  The potential difference generated in the first piezoelectric unit 3a is transmitted to the control unit 40 of the ultrasonic sensor unit 10 as an output signal of the ultrasonic reception sensor 53 through the wirings 6a and 7 connected to the upper electrode 5 and the first lower electrode 4a. Is done. Output signals from the individual ultrasonic reception sensors 53 transmitted to the control unit 40 of the ultrasonic sensor unit 10 are sent to the storage unit 42 via the T / R switch 45, the amplification unit 44a, and the A / D conversion unit 44b. Remembered. The control / calculation unit 41 calculates and outputs the distance and moving speed from the output signals of the individual ultrasonic reception sensors 53 stored in the storage unit 42 to the human hand or finger in the detection area.

The arithmetic control unit (not shown) of the PDA 100 recognizes the state and operation of the hand and finger from the distance and moving speed to the human hand and finger output from the ultrasonic sensor unit 10, and registers the hand and finger in advance. Compare with state and action. As a result of the comparison, if the detected state or action of the human hand or finger matches that registered in advance, the arithmetic control unit of the PDA 100 recognizes the shape or action of the human hand or finger as a predetermined input, for example, A predetermined operation such as displaying an image on the display unit 20 is executed.
Therefore, according to the PDA 100 of this embodiment, the ultrasonic sensor unit 10 can function as an input device.

  Here, in the ultrasonic transmission sensor 52 and the ultrasonic reception sensor 53 provided in the ultrasonic sensor unit 10, the piezoelectric body 3 is constituted by the first piezoelectric portion 3 a and the second piezoelectric portion 3 b. Therefore, the static deflection amount and the deflection direction of the diaphragm 2 can be controlled by the applied voltage applied to the second piezoelectric portion 3b. As a result, when the diaphragm 2 is vibrated by the first piezoelectric unit 3 a and ultrasonic waves are transmitted, the amount and direction of deflection of the diaphragm 2 are controlled by the second piezoelectric unit 3 b, and the ultrasonic wave in the ultrasonic transmission sensor 52 is controlled. Sound wave directivity and transmission characteristics can be controlled.

  Further, the vibration state of the diaphragm 2 by the ultrasonic wave incident on the vibration region V of the diaphragm 2 is controlled by controlling the amount and direction of deflection of the diaphragm 2 by the second piezoelectric section 3b, and the first piezoelectric section The input signal can be adjusted by changing the voltage generated by deformation of 3a. Thereby, it is possible to control the sensitivity and reception characteristics of the ultrasonic waves in the ultrasonic wave reception sensor 53.

  Also, as shown in FIG. 8 (b), the diaphragm 2 is bent so as to be concave toward the base 11, thereby converging the ultrasonic waves generated by the vibration of the diaphragm 2, The reach can be adjusted.

  Further, in the ultrasonic transmission sensor 52 and the ultrasonic reception sensor 53 of the present embodiment, the first piezoelectric portion 3a and the second piezoelectric portion 3b are integrally provided, and the first lower electrode 4a and the second lower electrode are provided. 4b is separated. Thereby, different applied voltages can be applied to the first piezoelectric part 3a and the second piezoelectric part 3b, and the first piezoelectric part 3a and the second piezoelectric part 3b can be driven individually. In addition, the potential difference generated in the first piezoelectric portion 3a due to the vibration of the diaphragm 2 can be detected in a state where the diaphragm 2 is statically bent by the second piezoelectric portion 3b. In addition, the piezoelectric body 3 can be easily manufactured, the productivity of the ultrasonic transmission sensor 52 and the ultrasonic reception sensor 53 can be improved, and the production cost of the ultrasonic sensor unit 10 can be reduced.

  Further, the ultrasonic transmission sensor 52 and the ultrasonic reception sensor 53 of the present embodiment are provided so that the diaphragm 2 closes the openings 11a and 61a of the base portions 11 and 61, and the first piezoelectric portion 3a and the first piezoelectric portion 3a. The two piezoelectric parts 3 b are provided in the vibration region V of the diaphragm 2. Accordingly, the diaphragm 2 can be supported by the base portions 11 and 61 and only the vibration region V of the diaphragm 2 can be vibrated. Further, the natural frequency of the diaphragm 2 in the vibration region V can be adjusted by the size and shape of the openings 11a and 61a. In addition, the vibration region V of the diaphragm 2 is vibrated by the first piezoelectric unit 3a while the vibration region V of the diaphragm 2 is statically bent by the second piezoelectric unit 3b, or the vibration region V of the diaphragm 2 is vibrated. The first piezoelectric portion 3a can be deformed by this vibration.

  Further, in the ultrasonic transmission sensor 52 and the ultrasonic reception sensor 53 of the present embodiment, the first piezoelectric portion 3a is provided at the center of the vibration region V, and the second piezoelectric portion 3b is the periphery of the first piezoelectric portion 3a. Is provided. Accordingly, the peripheral portion of the vibration region V of the diaphragm 2 can be deformed by the second piezoelectric portion 3b, and the diaphragm 2 in the vibration region V can be bent convexly or concavely toward the bases 11 and 61 side. The vibration plate 2 bent in a convex shape or a concave shape can be vibrated by the first piezoelectric portion 3a, or the first piezoelectric portion 3a can be deformed by the vibration of the vibration plate 2 bent in a convex shape or a concave shape.

  Further, in the ultrasonic transmission sensor 52 and the ultrasonic reception sensor 53 of the present embodiment, the second piezoelectric portion 3 b is provided in the vicinity of the boundary of the vibration region V. As a result, the vicinity of the vibration region V of the diaphragm 2 can be deformed, and the vibration region V of the diaphragm 2 can be efficiently bent toward the base 11 side by a convex shape or a concave shape.

As described above, according to the ultrasonic sensor unit 10 of the present embodiment, the ultrasonic transmission sensor array 50 and the ultrasonic reception sensor array 51 which are configured under optimum conditions suitable for each are independently provided. Therefore, the ultrasonic transmission sensor 52 for generating a strong sound pressure and the ultrasonic reception sensor 53 with excellent reception sensitivity are provided. The ultrasonic sensor unit 10 can exhibit the maximum performance both when transmitting and receiving ultrasonic waves, and has excellent reliability.
In addition, since the ultrasonic sensor unit 10 is bonded to the ultrasonic sensor array 50 and the ultrasonic sensor array 51 for transmission, the rigidity of the sensor unit itself can be increased, and at the time of transmitting and receiving ultrasonic waves. Time reliability can be improved.

(Second embodiment)
Next, the ultrasonic sensor unit according to the second embodiment of the present invention will be described. Note that the difference between the ultrasonic sensor unit according to the present embodiment and the ultrasonic sensor unit according to the first embodiment is the arrangement structure of the ultrasonic sensors, and other configurations are common. Therefore, the same code | symbol is attached | subjected about the member common to 1st embodiment, and the detailed description is abbreviate | omitted.

  FIG. 9A is a diagram illustrating a planar configuration of the ultrasonic transmission sensor array according to the present embodiment, and FIG. 9B is a diagram illustrating a planar configuration of the ultrasonic reception sensor array according to the present embodiment. is there. FIG. 10 is a diagram showing a planar structure of the ultrasonic sensor unit according to the present embodiment.

As shown in FIG. 9A, the ultrasonic transmission sensor array 50 according to the present embodiment has a plurality of ultrasonic transmission sensors 52 arranged concentrically. Further, the base portion 11 is regularly formed with a plurality of through holes 11b having a substantially circular shape in a plan view in a concentric manner. Specifically, the through hole 11b is formed in the base 11 so as to be concentric with the opening 11a.
As shown in FIG. 9B, the ultrasonic reception sensor array 51 according to the present embodiment has a plurality of ultrasonic transmission sensors 52 arranged concentrically.

  As shown in FIG. 10, the ultrasonic sensor unit 100 is configured by bonding an ultrasonic transmission sensor array 50 and an ultrasonic reception sensor array 51 together. The ultrasonic transmission sensor array 50 and the ultrasonic reception sensor array 51 are bonded so that the ultrasonic transmission sensor 52 and the ultrasonic reception sensor 53 do not overlap in a plan view. The ultrasonic reception sensor 53 is exposed in the through hole 11 b formed in the base 11 of the ultrasonic transmission sensor unit 50. Thereby, the ultrasonic reception sensor array 51 can receive predetermined ultrasonic waves by the ultrasonic reception sensor array 51 exposed in the through hole 11b.

  Also in the ultrasonic sensor unit 100 of the present embodiment, since the ultrasonic transmission sensor array 50 and the ultrasonic reception sensor array 51 are provided independently, the ultrasonic transmission sensor 52 that produces a strong sound pressure and the reception sensitivity are excellent. The ultrasonic wave reception sensor 53 is provided. Therefore, the maximum performance can be exhibited both when transmitting and receiving ultrasonic waves, and the reliability is excellent.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the planar shape of the openings 11a and 61a formed in the base portions 11 and 61 is not limited to a circular shape, and the planar shape of the through hole 11b formed in the base portion 11 is not limited to a rectangular shape.

  In the embodiment described above, the case where the through hole 11b is formed in the base portion 11 of the ultrasonic transmission sensor array 50 has been described. However, the through hole 61b is formed in the base portion 61 of the ultrasonic reception sensor array 51. May be. That is, the order of bonding of the ultrasonic transmission sensor array 50 and the ultrasonic reception sensor array 51 may be changed.

  In the first embodiment, the ultrasonic transmission sensor 52 and the ultrasonic reception sensor 53 are arranged in a matrix in a plan view. In the second embodiment, the ultrasonic transmission sensor 52 and the ultrasonic transmission sensor 53 are arranged in a matrix. Although the case where the sound wave reception sensors 53 are arranged concentrically in a plan view has been described, the present invention is not limited to this. For example, one of the ultrasonic transmission sensor 52 and the ultrasonic reception sensor 53 is arranged in a matrix, and the other of the ultrasonic transmission sensor 52 and the ultrasonic reception sensor 53 is arranged concentrically. Also good.

(Third embodiment)
Subsequently, an ultrasonic sensor unit according to a third embodiment of the present invention will be described. The difference between the ultrasonic sensor unit according to the present embodiment and the ultrasonic sensor unit according to the first embodiment is that the arrangement direction of the ultrasonic transmission sensor array and the ultrasonic reception sensor array and the attachment position thereof are as follows. The other configurations are common. Therefore, the same code | symbol is attached | subjected about the member common to 1st embodiment, and the detailed description is abbreviate | omitted.

FIGS. 11A to 11C are schematic diagrams illustrating the attachment state of the ultrasonic transmission sensor array 50 and the ultrasonic reception sensor array 51 according to the first embodiment, the third embodiment, and the fourth embodiment, respectively. It is a figure, Comprising: In the figure, the paper surface upper direction is a transmission direction of an ultrasonic wave. FIG. 12 is an enlarged view of a main part of the ultrasonic sensor unit according to the third embodiment.
In the following description, the surface on which the ultrasonic transmission sensor 52 is formed in the base 11 of the ultrasonic transmission sensor array 50, that is, the surface on which the piezoelectric body 3 is formed is the transmission-side surface 50a, and the surface on the opposite side. Is referred to as a transmitting-side back surface 50b. In exactly the same manner, the surface on which the ultrasonic receiving sensor 53 is formed in the base 61 of the ultrasonic receiving sensor array 51 is referred to as a receiving-side surface 51a, and the opposite surface is referred to as a receiving-side back surface 51b. In addition, it is assumed that the ultrasonic wave is transmitted upward from the ultrasonic transmission sensor 52 in FIG.

As shown in FIG. 11A, in the above-described first embodiment, the transmission-side surface 50a of the ultrasonic transmission sensor array 50 and the reception-side surface 51a of the ultrasonic reception sensor array 51 are in the same direction. The ultrasonic receiving sensor array 51 is laminated on the ultrasonic transmitting sensor array 50 so as to be laminated.
On the other hand, in the present embodiment, as shown in FIG. 11B, the transmission side surface 50a of the ultrasonic transmission sensor array 50 and the reception side surface 51a of the ultrasonic reception sensor array 51 are reversed. They are directed to each other and are bonded to each other at the peripheral portions of the transmission-side surface 50a and the reception-side surface 51a. As shown in FIG. 12, from the second lower electrodes 4b of the transmission-side surface 50a and the reception-side surface 51a respectively. Each drawn wiring 6b is connected to a ground wiring (not shown).

The ground wiring maintains a constant voltage in the first lower electrode 4a that applies a voltage to the piezoelectric body 3 on the transmission side surface 50a and the first lower electrode 4a that extracts a voltage generated from the piezoelectric body 3 on the reception side surface 51a. In FIG. 12, it extends in the depth direction of the drawing sheet. In the present embodiment, the piezoelectric body 3 and the electrodes 4 and 5 are wired on the base 11 of the ultrasonic transmission sensor array 50 on the lower side of the sensor unit.
On the other hand, the ultrasonic receiving sensor array 51 is provided with a connection terminal (not shown) drawn from the wiring 6b without providing a ground wiring, and with the transmitting side surface 50a and the receiving side surface 51a attached to each other. By bonding, the connection terminal is connected to the wiring 6b on the transmission side surface 50a to share the ground wiring.

With such a configuration, it is only necessary to provide patterning of the ground wiring only on one base, so that the manufacturing process can be simplified and the production cost can be reduced.
In the present embodiment, the shared wiring is the ground wiring, but the present invention is not limited to this, and various modifications can be made without departing from the spirit of the present invention. Other wiring may be shared. For the same purpose, the shared wiring may be formed not only on the transmission-side surface 50a but also on the reception-side surface 51a. The ultrasonic transmission direction from the ultrasonic transmission sensor 50 is downward in FIG. May be transmitted toward the destination.

(Fourth embodiment)
In the present embodiment, the ultrasonic sensor unit is different from the ultrasonic sensor unit in the third embodiment described above, as shown in FIG. 11C, the ultrasonic transmission sensor array 50 and the ultrasonic reception sensor. The array 51 is pasted on the transmission-side back surface 50b and the reception-side back surface 51b.

According to such a configuration, the base portions 11 and 61 of each sensor array are interposed between the diaphragms 2 of the ultrasonic transmission sensor 52 and the ultrasonic reception sensor 53.
When a strong sound pressure is produced by the ultrasonic transmission sensor 52, the diaphragm 2 is greatly bent, but in this embodiment, it is compared with the ultrasonic sensor unit in the first embodiment and the third embodiment. Since the distance between the diaphragms 2 is increased, the attenuation of the sound pressure of the ultrasonic waves propagating in the air increases, so that the crosstalk that is directly received by the ultrasonic reception sensor 53 is reduced. The degree can be reduced. In addition, since the base portions 11 and 61 are interposed, the ultrasonic wave propagating through the sensor unit itself also has a high degree of reduction, so that crosstalk can be reduced and the ultrasonic reception sensor can be made more sensitive. Can be a thing. The ultrasonic sensor unit 10 includes an ultrasonic transmission sensor 52 that generates a strong sound pressure and an ultrasonic reception sensor 53 that has excellent reception sensitivity, and is the maximum in both transmission and reception of ultrasonic waves. It is capable of exhibiting limited performance and is excellent in reliability.

DESCRIPTION OF SYMBOLS 2 ... Diaphragm, 3 ... Piezoelectric body, 4 ... Lower electrode, 5 ... Upper electrode, 10 ... Ultrasonic sensor unit, 11b ... Through-hole, 50 ... Ultrasonic transmission sensor array, 50a ... Transmission side surface, 50b ... Transmission Side back surface 51... Ultrasonic reception sensor array, 51 a. Reception side surface, 51 b. Reception side back surface, 52.

Claims (6)

An ultrasonic transmission sensor array having a plurality of ultrasonic transmission sensors each including a piezoelectric body that transmits ultrasonic waves on one surface thereof;
An ultrasonic receiving sensor array having a plurality of ultrasonic receiving sensors made of a piezoelectric body for receiving the ultrasonic waves on one side surface thereof,
The ultrasonic transmission sensor array and the ultrasonic reception sensor array are not overlapped in a state in which the ultrasonic transmission sensor and the ultrasonic reception sensor are viewed in plan view,
And the transmission side surface provided with the ultrasonic transmission sensor of the ultrasonic transmission sensor array and the reception side surface provided with the ultrasonic reception sensor of the ultrasonic reception sensor array have the same direction. It is pasted to face,
One of the ultrasonic transmission sensor array and the ultrasonic reception sensor array is formed with a through hole for exposing the ultrasonic sensor in the other array. An ultrasonic transmission sensor array having a plurality of ultrasonic transmission sensors each including a piezoelectric body that transmits ultrasonic waves on one surface thereof;
An ultrasonic receiving sensor array having a plurality of ultrasonic receiving sensors made of a piezoelectric body for receiving the ultrasonic waves on one side surface thereof,
The ultrasonic transmission sensor array and the ultrasonic reception sensor array are not overlapped in a state in which the ultrasonic transmission sensor and the ultrasonic reception sensor are viewed in plan view,
And either one of the transmission side surface provided with the ultrasonic transmission sensor of the ultrasonic transmission sensor array and the reception side surface provided with the ultrasonic reception sensor of the ultrasonic reception sensor array, Orient the direction opposite to the ultrasonic transmission direction of the ultrasonic transmission sensor,
The transmission side surface and the reception side surface are bonded together,
One of the ultrasonic transmission sensor array and the ultrasonic reception sensor array is formed with a through hole for exposing the ultrasonic sensor in the other array. An ultrasonic transmission sensor array having a plurality of ultrasonic transmission sensors each including a piezoelectric body that transmits ultrasonic waves on one surface thereof;
An ultrasonic receiving sensor array having a plurality of ultrasonic receiving sensors made of a piezoelectric body for receiving the ultrasonic waves on one side surface thereof,
The ultrasonic transmission sensor array and the ultrasonic reception sensor array are not overlapped in a state in which the ultrasonic transmission sensor and the ultrasonic reception sensor are viewed in plan view,
And either one of the transmission side surface provided with the ultrasonic transmission sensor of the ultrasonic transmission sensor array and the reception side surface provided with the ultrasonic reception sensor of the ultrasonic reception sensor array, Orient the direction opposite to the ultrasonic transmission direction of the ultrasonic transmission sensor,
The transmission side back surface of the ultrasonic transmission sensor array not equipped with the ultrasonic transmission sensor and the reception side back surface of the ultrasonic reception sensor array not equipped with the ultrasonic reception sensor are bonded together,
One of the ultrasonic transmission sensor array and the ultrasonic reception sensor array is formed with a through hole for exposing the ultrasonic sensor in the other array.   The ultrasonic transmission sensor is regularly arranged in the ultrasonic transmission sensor array, and the ultrasonic reception sensor is regularly arranged in the ultrasonic reception sensor array. The ultrasonic sensor unit according to any one of claims 1 to 3.   The arrangement pattern of the ultrasonic transmission sensor in the ultrasonic transmission sensor array is different from the arrangement pattern of the ultrasonic transmission sensor in the ultrasonic reception sensor array. The described ultrasonic sensor unit.   The number of the ultrasonic transmission sensors in the ultrasonic transmission sensor array is different from the number of the ultrasonic reception sensors in the ultrasonic reception sensor array. The ultrasonic sensor unit according to Item.

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