The present invention relates to an ultrasonic speaker suitable for a parametric speaker.
For example, Japanese Registered Patent No. 6707242 and the like disclose related art examples of an array type parametric speaker using ultrasonic speakers.
Some of the related art examples have adopted a structure in which a case is provided with a step so that the inner diameter of the bottom surface of the case is smaller than the inner diameter of the top surface (opening portion) of the case, and a substrate is placed on the top surface of the step.
In the case where this structure is adopted, even when ultrasonic speakers are arranged to be spread all over as densely as possible as shown in
Therefore, the present invention has an object to provide an ultrasonic speaker capable of increasing an effective vibration area as compared with the size of a substrate and improving the characteristics of a parametric speaker.
An ultrasonic speaker of the present invention comprises a case that has an opened top surface and includes a plurality of protrusions protruding inward on an inner side surface of the case, a piezoelectric element fixed to a bottom surface in the case, and a substrate that is inserted in the case and placed on upper surfaces of the plurality of protrusions.
According to the ultrasonic speaker of the present invention, the effective vibration area can be increased as compared with the size of the substrate, and the characteristics of the parametric speaker can be improved.
Hereinafter, an embodiment of the present invention will be described in detail. Components having the same functions are designated by the same reference numerals, and duplicative description thereon will be omitted.
Hereinafter, the structure of an ultrasonic speaker of a first embodiment will be described with reference to
As shown in the cross-sectional view of
It is preferable to arrange the protrusions 111 on the upper and lower stages at positions where the substrate 14 is held between the protrusions 111 on the upper and lower stages by inserting the substrate 14 into the case 11 while the notches 141 are aligned with the protrusions 111 on the upper stage to allow the substrate 14 to pass through the protrusions 111 on the upper stage, and then rotating the substrate 14 by a predetermined angle with a vertical direction set as a rotation axis (see
For example, a total of three protrusions 111 on the upper stage are provided to be arranged at angular intervals of 120°, and a total of three protrusions 111 on the lower stage are provided to be likewise arranged at angular intervals of 120° and further rotationally shifted by 60° from the three protrusions 111 on the upper stage respectively. The substrate 14 has a total of three notches 141 arranged at angular intervals of 120°. The substrate 14 is passed through the protrusions 111 on the upper stage, and then rotated by about 30° with the vertical direction set as the rotation axis, whereby the substrate 14 can be fixed. Note that the distance in the vertical direction between the lower surface of each protrusion 111 on the upper stage and the upper surface of each protrusion 111 on the lower stage is substantially equal to the thickness of the substrate 14.
The ultrasonic speaker 1 of the present embodiment is configured so that the protrusions 111 protruding inward are provided in the case 11, and the substrate 14 is placed on the upper surfaces of the protrusions 111. Therefore, the inner diameter of the bottom surface of the case can be made equal to the inner diameter of the top surface of the case, so that the gap g occurring between adjacent ultrasonic speakers can be almost eliminated (the adjacent pitch can be reduced), the effective vibration area can be increased, and the characteristics of the parametric speaker can be improved.
According to the ultrasonic speaker 1 of the present embodiment, the protrusions 111 on the upper and lower stages are arranged at positions where the substrate 14 is held between the protrusions 111 on the upper and lower stages by passing the substrate 14 through the protrusions 111 on the upper stage and then rotating the substrate 14 by a predetermined angle with the vertical direction set as the rotation axis. Therefore, the substrate 14 can be fixed by interposing the substrate 14 between the protrusions 111 on the upper and lower stages, and a step of soldering lead wires to the substrate 14 can be easily performed (in the related art, a substrate is simply placed on the pedestal of a case, so that when a piezoelectric element is soldered and connected to the substrate with lead wires, it is necessary to hold the substrate so that the substrate does not move). Further, this structure also contributes to holding the substrate 14 horizontally. For example, even when the upper surface of the substrate 14 is filled with a sealing material (silicon) or the like in order to improve the characteristics, it is possible to prevent the substrate 14 from tilting due to the weight of the sealing material (silicon).
Number | Date | Country | Kind |
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2020-173050 | Oct 2020 | JP | national |
Number | Name | Date | Kind |
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20110290028 | Matsumoto | Dec 2011 | A1 |
Number | Date | Country |
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H11-266498 | Sep 1999 | JP |
2006-352829 | Dec 2006 | JP |
2007-318742 | Dec 2007 | JP |
2012-114539 | Jun 2012 | JP |
2018-101924 | Jun 2018 | JP |
6707242 | Jun 2020 | JP |
Entry |
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Extended European Search Report in Corresponding Ep Application No. 21200101.0, dated Mar. 10, 2022. |
Number | Date | Country | |
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20220116699 A1 | Apr 2022 | US |