Classifications

• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
  • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
  • H03H9/02—Details
  • H03H9/05—Holders; Supports
  • H03H9/10—Mounting in enclosures
  • H03H9/1007—Mounting in enclosures for bulk acoustic wave [BAW] devices
  • H03H9/1035—Mounting in enclosures for bulk acoustic wave [BAW] devices the enclosure being defined by two sealing substrates sandwiching the piezoelectric layer of the BAW device
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
  • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
  • H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
  • H03H9/21—Crystal tuning forks
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
  • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
  • H03H9/46—Filters
  • H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
  • H03H9/58—Multiple crystal filters
  • H03H9/60—Electric coupling means therefor
  • H03H9/605—Electric coupling means therefor consisting of a ladder configuration

Definitions

• the present invention relates to a ladder type filter, and more particularly to a ladder type filter in which a series resonator and a parallel resonator are configured using a tuning fork type piezoelectric resonator.
• Fig. 2 shows an example of the structure of a conventional ladder-type filter.
• This ladder-type filter is configured by using a plurality of piezoelectric resonators that use a square plate expansion vibration mode.
• the four-element two-stage ladder filter shown in the circuit diagram of Fig. 3 is constructed using the rectangular plate-shaped series resonators 1 and 2 and the rectangular plate-shaped parallel resonators 3 and 4 as well. I have.
• reference numeral 2a denotes an electrode formed on one main surface of the series resonator, and a similar electrode is formed on the other main surface of the series resonator 2. Further, similar electrodes are formed on both main surfaces of the series resonator 1.
• the parallel resonators 3 and 4 have electrodes 3a and 4a formed on the entire surfaces of both main surfaces.
• Reference numerals 5 to 11 indicate metal terminals, which are used to electrically connect the series resonators 1 and 2 and the parallel resonators 3 and 4 to each other as shown in FIG.
• the metal terminals 5 to 11 are housed together with the series resonators 1 and 2 and the parallel resonators 3 and 4 in a case 12 made of an insulating material.
• the upper opening 1 2a of the case material 12 is closed by a lid material (not shown).
• One ladder-type filter component is configured.
• the metal terminals 9 to 11 are drawn out of the case and used as connection terminals with the outside.
• the series resonators 1 and 2 and the parallel resonators 3 and 4 can vibrate in a desired manner while being housed in the case 12. That is, the resonators 1 to 4 should not be prevented from vibrating while housed in the case 12. Therefore, a so-called spring terminal having spring properties is used as the metal terminal 11 located at the end.
• a spring terminal is used as the metal terminal 11 so as not to hinder the vibrations of the resonators 1 to 4 housed in the case 12. Therefore, the overall size of the ladder-type filter tended to be considerably large.
• the dimensions when configured as a final ladder-type filter component are: 7. Q mm X 8.0 mm x thickness of about 8.0 mm Had become.
• an object of the present invention is to provide a ladder-type filer that can be configured as a surface-mounted electronic component and that has a small overall shape. Is to provide.
• the present invention is a ladder type filter in which at least one series resonator and at least one parallel resonator are connected, and has the following configuration.
• a second slit extending inward from one end of the piezoelectric substrate is sandwiched by a first slit ′ extending inward from one end of the piezoelectric substrate.
• a tuning fork type piezoelectric resonator is used.
• the plurality of tuning fork type piezoelectric resonators constituting the series resonator and the parallel resonator reduce the vibration of the tuning fork vibrating portions of the tuning fork type piezoelectric resonators on both sides. They are laminated and integrated via a cavity-forming material so as to form a laminated body by forming a cavity that does not obstruct it.
• a plurality of tuning-fork type piezoelectric resonators constituted by using a piezoelectric substrate are stacked and integrated via a cavity forming material, that is, since they are stacked and integrated without using a spring terminal,
• the overall dimensions of the ladder type filter are very small, and it is possible to make it particularly thin.
• FIG. 1 is an exploded perspective view showing the entire structure of a ladder-type filter according to one embodiment of the present invention.
• FIG. 2 is an exploded perspective view for explaining the structure of a conventional ladder type filter.
• Fig. 3 is a diagram showing the circuit of a conventional ladder type filter.
• FIG. 4 is an exploded perspective view showing a main part of the embodiment shown in FIG.
• FIG. 5 is an exploded perspective view showing another main part of the embodiment shown in FIG.
• FIG. 6 is a schematic exploded perspective view for explaining an electrode pattern of one series resonator.
• FIG. 7 is a schematic exploded perspective view for explaining an electrode pattern of one parallel resonator.
• FIG. 8 is a schematic exploded perspective view for explaining an electrode pattern of another series resonator.
• FIG. 9 is a schematic exploded perspective view for explaining an electrode pattern of another parallel resonator.
• FIG. 10 is an external perspective view showing the ladder filter of the embodiment.
• FIG. 11 is a diagram illustrating a circuit of a ladder-type filter according to the embodiment.
• FIG. 12 is a diagram showing the attenuation-frequency characteristics of the ladder filter according to the present invention.
• FIG. 1 is an exploded perspective view showing a main part of a ladder-type filter according to one embodiment of the present invention.
• series resonators 21 and 22 and parallel resonators 23 and 24 are alternately stacked as shown in FIG. Le Yue is composed.
• the series resonators 21 and 22 and the parallel resonators 23 and 24 are laminated via cavity forming materials 25 to 27.
• Substrates 30a and 30b are laminated on the upper and lower sides of the laminate via the same cavity forming materials 28 and 29, respectively.
• the series resonator 21 extends inward from one end of the piezoelectric substrate 21 to the first to third slits 21 to 21.
• a tuning fork-shaped vibrating portion is formed between the second and third slits 21, 21.
• a vibrating electrode 215 is formed on the tuning fork-shaped vibrating portion c.
• a vibrating electrode 2 16 is also formed on the lower surface of the piezoelectric substrate 211 so as to face the vibrating electrode 2 15. Therefore, the vibrating electrodes 2 1 5 and 2 1 6 When an AC voltage is applied from above, the tuning fork-like vibrating portion surrounded by the second and third slits 21 and 21 vibrates as a piezoelectric tuning fork.
• 2 17 a and 2 17 b indicate connection conductive parts, and the vibrating electrodes 2 15 and 2 16 are respectively connected to the terminal electrodes 2 by the connection conductive parts 2 17 a and 2 17 b. It is drawn to 18 and 2 19.
• the vibrating electrodes 2 15; 2 16 formed on both main surfaces are formed at different corners of the piezoelectric substrate 2 11 as is clear from FIGS. 4 and 6. Terminal electrodes 218 and 219.
• spacer 31 is arranged in front of a portion of series resonator 21 where a tuning fork-shaped vibrating portion is formed, with gap 31a therebetween.
• the gap 31a is provided so as not to hinder the vibration of the tuning fork-shaped vibrating portion.
• the series resonator 21 and the spacer 31 are laminated with the lower parallel resonator 23 and the spacer 33 via a rectangular frame-shaped cavity forming material 25.
• the rectangular frame-shaped cavity forming material 25 is provided to form a cavity that does not hinder the vibration of the tuning fork vibrating portions of the upper and lower series resonators 21 and the parallel resonators 23.
• the cavity forming material 25 is formed of a frame-like member having an opening. This cavity forming material can be formed by applying an adhesive so as to have the shape shown in the figure and finally curing the material, or by using an elastic rubber, a synthetic resin or the like formed into a rectangular frame shape shown in the figure. .
• a predetermined thickness is required as shown in the figure. It is necessary to be structured as follows.
• the parallel resonator 23 has first to third slits 23 to 24 formed on a piezoelectric substrate 231, and vibrating electrodes 23 to 35 shown in FIG. 7 on both main surfaces. , 236 are formed.
• the vibrating electrodes 235 and 236 are led out to the terminal electrodes 238 and 239 by the connecting conductive portions 237a and 237b, respectively.
• the first terminal electrode 238 of the parallel resonator 23 is formed at the center of the edge of the piezoelectric substrate 231, and the other terminal electrode 239 is formed. Is formed at one corner of the piezoelectric substrate 2 31.
• FIGS. 8 and 9 show details of the portion where the series resonator 22 and the parallel resonator 24 of FIG. 1 are stacked, and the upper series resonator 2 1
• FIG. 8 is a diagram corresponding to FIGS. 4, 6, and 7 used to explain the parallel resonator 23. Therefore, the lower series resonators 22 and parallel resonators 24, as well as the cavity forming material 27 and spacers 32, 34 are given the same reference numerals as described above. Is omitted.
• the ladder type filter of the present embodiment is configured by laminating and integrating the components shown in FIG. That is, as shown in FIG. 10, by forming the external electrodes 41 to 46 on both end surfaces of the laminated body 40 which is laminated and integrated, the ladder type of the embodiment is formed. Phil evening 20 is obtained.
• the external electrode 41 is connected to the terminal electrode 2 18 of the series resonator 21.
• the external electrode 42 is connected to the terminal electrode 23 of the parallel resonator 23, and the external electrode 43 is connected to the terminal electrode 21 of the series resonator 21 and the terminal electrode of the parallel resonator 23. Connected to 239.
• the external electrode 4 is connected to the terminal electrode 22 9 of the series resonator 22 and the terminal electrode 24 9 of the parallel resonator 24, and the external electrode 45 is connected to the terminal electrode 24 of the parallel resonator 24.
• the external electrode 46 is connected to the terminal electrode 228 of the series resonator 22.
• the ladder-type filter shown in FIG. 11 is constructed by connecting the external electrode 43 and the external electrode 46 on the outer surface of the laminate 40 or on the outside.
• a series resonator 22 and a parallel resonator 23 are formed by a tuning-fork type piezoelectric resonator configured using a piezoelectric substrate. 24, and the resonators 21 to 24 are laminated and integrated via the hollow components 25 to 27, making the overall thickness extremely small and extremely thin.
• a ladder type 1 filter can be configured as a part of the filter. When a two-stage ladder type filter 20 incorporating the above four elements was actually manufactured, the dimensions were 6.2 ⁇ 5.0 ⁇ 2.0 mm. Therefore, it can be seen that the overall dimensions are considerably smaller than the conventional ladder-type filter shown in FIG.
• FIG. 12 shows the attenuation-frequency characteristics of the ladder type filter of the present invention.
• the characteristics indicated by solid line A, broken line B, and solid line C shown in Fig. 12 are respectively composed of a single-stage, two-stage, and four-stage (two connected two-stage) ladder-type filters. This is the characteristic in the case of doing.
• the capacitance of the tuning-fork type piezoelectric resonator used to construct each ladder-type filter is as follows.
• the tuning-fork type piezoelectric resonator used in the present invention is not limited to the one having the electrode structure described with reference to FIGS. That is, the piezoelectric substrate has a structure in which first to third slits extending from one edge of the piezoelectric substrate are formed, and a tuning fork-shaped vibrating portion is formed in a portion sandwiched between the second and third slits. As long as it has a vibration electrode of another pattern, it can be used in the present invention.

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• Physics & Mathematics (AREA)
• Acoustics & Sound (AREA)
• Chemical & Material Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)

Priority Applications (2)

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Publications (1)

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ID=12798226

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Cited By (8)

Families Citing this family (3)

Citations (4)

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• 1991
  • 1991-03-13 JP JP4825191A patent/JPH04284015A/ja active Pending
• 1992
  • 1992-03-12 DE DE4290741A patent/DE4290741C2/de not_active Expired - Fee Related
  • 1992-03-12 WO PCT/JP1992/000300 patent/WO1992016997A1/ja active Application Filing
  • 1992-03-12 DE DE19924290741 patent/DE4290741T1/de active Pending

Patent Citations (4)

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